With a non-traditional phono cartridge design NAGAOKA’s MP-700 elevates the vinyl record listening experience at a rather steep price Nagaoka, a renowned manufacturer of phono styli and cartridges, has announced its new flagship model in the esteemed MP Series — the MP-700 The cartridge will make its official debut at High End Munich 2025 this marks the cartridge’s premiere at the final Munich edition of the show before it relocates to Austria in 2026 Nagaoka takes a unique approach with the MP-700, opting for a Moving Permalloy (MP) design rather than a conventional Moving Magnet (MM) configuration a lightweight permalloy element is affixed to the cantilever This allows the stylus to track with greater speed The MP-700 features a boron cantilever paired with a newly developed micro-ridge nude diamond stylus measuring 0.12 x 0.3 mil This high-performance combo boosts accuracy and detail retrieval allowing it to extract the finest nuances from vinyl grooves the MP-700 uses the softest damper in the entire NAGAOKA MP series enabling the boron cantilever and stylus to operate with greater freedom and sensitivity While a softer damper can sometimes raise concerns about stability NAGAOKA has countered this with a newly integrated suspension wire in the pivot system—delivering both responsiveness and control The suspension wire effectively manages the movement of both the cantilever and stylus ensuring stability without compromising clarity—especially in the high frequencies and more accurate bass and timbral reproduction lifelike listening experience that brings your vinyl collection to life The MP-700 comes with a shielded case and cartridge frame crafted from ultra-duralumin enhanced with a three-layer surface treatment: nickel plating This treatment minimizes static interference There are a wide range of phono cartridges available, and the NAGAOKA MP-110 from our 2024 Editors’ Choice list is an affordable option for modest systems if you have a high-end turntable and audio system the NAGAOKA MP-700’s unique design might deliver the performance you are seeking If you are attending High End Munich 2025 NAGAOKA is expected to be on hand showing off its design and capabilities.  The MP-700 will be available worldwide starting May 13 commemorating NAGAOKA’s 85 years anniversary Every NAGAOKA cartridge is handcrafted in Japan by skilled artisans upholding the brand’s commitment to precision and quality Home > Latest > New Products > Hi-Fi Components > Turntables, Phono Cartridges and Tonearms > Nagaoka Unveils MP-700 Moving Permalloy Phono Cartridge Ahead of High End Munich 2025  A Japanese brand that has been around for over 70 years Their mid-tier carts are highly underrated New and improved acoustic isolation feet that simply make loudspeakers sound better Just choose the size closest to the weight of your speaker The $349 Beosound A1 3rd Gen adds sound upgrades and the same IP67 waterproof build—still one of the most stylish portable Bluetooth.. the Tivoli Audio Model One BT 70's Color Collection is both a Bluetooth speaker and table-top radio in five retro colors Unlock the gates of Asgard with Schiit Valhalla 3 — a fully modern OTL/OCL tube headphone amp forged for high-impedance cans and audiophiles who.. the Audiolab D7 and D9 DACs feature ESS chips and versatile connectivity for audiophiles Upgrade Mom's home audio and video experiences this Mother's Day with 10 gift ideas she'll absolutely love -- and you might too Bandcamp's future is uncertain under Songtradr Here’s why indie artists still need your support—and why Spotify isn’t the answer in 2025 Are you one of those people who hates having to install a phono cartridge The Waiting for Ideas PP-1 might be exactly what you're.. Looking for ways to improve the sound from your turntable Our favorite phono preamplifiers we've tested offer a solution at every budget Chord Company's PhonoARAY can minimize external interference and ground issues that may affect turntable performance Upgrade the sound of your turntable with our favorite MM and MC phono cartridges you can buy in 2024 without breaking the bank Looking for your first high-end audiophile turntable but don't want to spend more than $3,500 for something that will be your deck for many.. Our favorite audiophile turntables in 2023 include Pro-Ject Our favorite turntables on sale for Black Friday 2024 that we would actually buy for ourselves or recommend to family and friends ecoustics is a hi-fi and music magazine offering product reviews, podcasts, news and advice for aspiring audiophiles, home theater enthusiasts and headphone hipsters. Read more → Copyright © 1999-2024 ecoustics | Disclaimer: We may earn a commission when you buy through links on our site The flagship MP-700 will make its debut at High End Munich next month Japanese cartridge brand Nagaoka is celebrating its 85th anniversary this year with a brand new flagship model, called the Nagaoka MP-700. It sits at the top of its long-running MP line of cartridges, and will be launched officially at the High End Munich show next month (15th to 18th May) Nagaoka started in 1940 as a maker of precision parts for clocks and watches, then moved on to fine jewellery before embarking on stylus tips and cartridge manufacturing. Its mid-range MP-200 cartridge impressed us so much with its all-round performance that it won a What Hi-Fi Award for the best cartridge over £250 The new flagship MP-700 cartridge is designed to deliver "ever more refined and accurate sound reproduction bringing listeners closer to the original performance." The MP in the name stands for Moving Permalloy a variation on the conventional moving-magnet cartridge design the MP design includes a lightweight permalloy piece attached to the cantilever and allowing more freedom and precision in the way the stylus moves The MP-700 features a boron cantilever and a micro-ridge nude diamond stylus measuring 0.12 x 0.3 mil which promises "exceptional detail retrieval from vinyl grooves" A newly integrated suspension wire in the pivot system further helps with stability separation and clarity across all frequencies The shielded case and cartridge frame are made from ultra-duralumin (a copper-aluminium alloy) which is further treated with a triple layer of nickel plating black tin plating and an insulating coating – all of which aims to protect it against static interference this cartridge won't come cheap when it becomes available in May The Nagaoka MP-700 will be available for £1149 / $1399 while the cartridge with headshell (MP-700H) costs £1249 / $1499 The replacement stylus JN-P700 will cost you £599 / $789 Let's hope its promise of delivering "accurate representation of treble bass tones and timbre for a more vivid and lifelike listening experience" comes true Read our Nagaoka MP-200 review Our guide to the best cartridges you can buy Moving magnet vs moving coil cartridges: which is right for you? During her time in the consumer tech industry she has reviewed hundreds of products (including speakers been to countless trade shows across the world and fallen in love with hi-fi kit much bigger than her Kash can be found tending to an ever-growing houseplant collection and shooing her cat Jolene away from spinning records you will then be prompted to enter your display name Launched officially at High End Munich 2025 the range-topping MP-700 Moving Permalloy cartridge honours Nagaoka’s 85-year commitment to precision and quality UK distributor Sound Design Distribution joins Nagaoka in welcoming the debut of the flagship MP-700 Moving Permalloy cartridge Celebrating NAGAOKA’s 85th Anniversary and launching at High End Munich 25 the MP-700 has been engineered for ever more refined and accurate sound reproduction bringing listeners closer to the original performance Compared with the conventional Moving Magnet (MM) type Nagaoka’s signature Moving Permalloy (MP) design utilises a lightweight permalloy piece attached to the cantilever while allowing the stylus to move with greater freedom and precision The new MP cartridge employs a boron cantilever paired with a new micro-ridge nude diamond stylus measuring 0.12 x 0.3 mil This precisely crafted combination enhances sound accuracy ensuring strong detail retrieval from vinyl grooves The MP-700 also incorporates the softest damper allowing the boron cantilever and micro-ridge stylus to perform at their best Its design includes a newly integrated suspension wire in the pivot system which effectively controls the movement of both the cantilever and stylus providing stability with enhanced separation and clarity across all frequencies to deliver the accurate representation of treble The MP-700 features a shielded case and cartridge frame crafted from ultra-duralumin enhanced with a three-layer surface treatment involving nickel plating MP-700H (cartridge + headshell): £1,249.00 The Company Pages refer to individual microsites created for companies where all press releases and stories featured on the Essential Install are collated These microsites serve as a comprehensive record of a company’s promotional activities over time This website is using a security service to protect itself from online attacks The action you just performed triggered the security solution There are several actions that could trigger this block including submitting a certain word or phrase You can email the site owner to let them know you were blocked Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page Photo: Courtesy of Honolulu Festival Foundation SEE ALSO: Things to Do on O‘ahu in March 2025 Photo: Courtesy of Liliko‘i Project Hawai‘i Celebrate International Women’s Day by supporting local female entrepreneurs at this sip-and-shop event You’ll meet more than 30 small business owners BUY TICKETS $15 admission, plus beverage tickets, located at a private club in downtown Honolulu, address provided with ticket purchase, eventbrite.com, @lilikoiprojecthawaii SEE ALSO: Your Insider Guide to Hōkūle‘a’s 50th Birthday Celebration Get hands-on with more than 50 construction trucks meet emergency responders and watch a Toyota truck show shop Kapolei Commons retailers and redeem your receipt for a complimentary toy truck Family-friendly, free, Kapolei Commons, 4450 Kapolei Pkwy., kapoleicommons.com, @kapoleicommons SEE ALSO: Your Ultimate Guide to Concerts and Live Music in Honolulu Scoop up gorgeous hand-built ceramic wares from Slo I Studio at potter Stacie Krajchir-Tom’s pop-up event at Olive Boutique 43 Kihapai St., Kailua, oliveandoliverhawaii.com, @olive_boutique Admire 77 stunning works by 58 Hawai‘i Watercolor Society member artists You’ll be in awe of the impressive range of pieces from landscapes and botanicals to figures and abstracts Stop by the First Friday Opening Reception on March 7 from 5 to 8 p.m to meet some of the artists and celebrate the exhibition Free, Downtown Art Center, Second Floor, 1041 Nu‘uanu Ave., hawaiiwatercolorsociety.org, @hawaiiwatercolorsociety SEE ALSO: 8 Amazing Things to Do With Kids Photo: Courtesy of La Pietra – Hawai‘i School for Girls Everyone (not just girls) is invited to explore cutting-edge technologies at this second annual community event test your skills on flight and racing simulators and jump into esports play There will also be plenty of low-tech activities BUY SCRIP + PARKING Family-friendly, free admission, scrip for purchase, La Pietra – Hawai‘i School for Girls, 2933 Poni Moi Road, lapietra.edu, @lapietraschool posted on Friday, 25th April 2025 by Steve May UK distributor Sound Design Distribution is bringing the flagship Nagaoka MP-700 Moving Permalloy cartridge to the UK and officially launching at High End Munich 25 the MP-700 has been engineered for absolutely accurate sound reproduction in order to bring listeners closer to the original performance This precisely crafted combo enhances sound accuracy ensuring exceptional detail retrieval from vinyl grooves providing stability with enhanced separation and clarity across all frequencies It’s said to deliver the accurate representation of treble bass tones and timbre for a more vivid and lifelike listening experience the MP-700H (cartridge + headshell) retails for £1,249 The JN-P700 replacement stylus is priced at £599 Inside CI Editor Steve May is a freelance technology specialist who also writes for T3, TechRadar, Home Cinema Choice, Trusted Reviews and The Luxe Review Please Login if your an existing member or Register a new account New reference hailed as the purest expression of Audiovector’s quest for musical truth Easy to install Fresnel screen said to be 100x brighter than conventional fabrics Is it a stand alone player, can it be operated for SACD/CD without having TV switched on ? from gerald bearman in High-end Pioneer UDP-LX500 UHD player aims to rule Will these new models sound any better than current models ? from gerald bearman in Yamaha intros new Aventage Atmos AV receivers att. Steve May . Have found analogue outs give excellent High End sound for CD ,but can not be used as there is no... from gerald bearman in Sony UBP-X1000ES UHD Blu-ray player review Inside CI © 2011  |  Web Development by Chocolate Grape image: Researchers from Nagaoka University of Technology Japan develop highly biocompatible apatite nanoparticles by manipulating surface properties through pH changes Credit: Motohiro Tagaya from Nagaoka University of Technology Medical implants have transformed healthcare offering innovative solutions with advanced materials and technologies many biomedical devices face challenges like insufficient cell adhesion leading to inflammatory responses after their implantation in the body particularly hydroxyapatite (HA)—a naturally occurring form of apatite found in bones have been shown to promote better integration with surrounding tissues the biocompatibility of artificially synthesized apatite nanoparticles often falls short of expectations primarily due to the nanoparticles’ limited ability to bind effectively with biological tissues Kazuto Sugimoto from Nagaoka University of Technology Tania Guadalupe Peñaflor Galindo from Sophia University Ryota Akutsu from Nagaoka University of Technology were also a part of this research team Apatites are a class of calcium-phosphorus-based inorganic compounds with hydroxyapatite—a naturally occurring form found in bones These compounds are known for their high biocompatibility Recent studies have found that coating artificial joints and implants with apatite nanoparticles is a plausible solution for improving the biocompatibility of these biodevices the artificially synthesized nanoparticles often show reduced binding affinity to biological tissues in vitro this difference could be linked to the nanoscale surface layer of the apatite nanoparticles Tagaya’s research was driven by a desire to unravel the complexities of biocompatible materials leading his team to develop an interdisciplinary framework that controls the intricate interactions between apatite and biological systems “The properties of the nanoscale surface layer of apatite nanoparticles are crucial when considered for medical coatings,” adds Dr we successfully controlled the nanoscale surface layers of apatite nanoparticles paving the way for advanced surface coating technologies for biodevices.” The team synthesized hydroxyapatite nanoparticles by mixing aqueous solutions of calcium and phosphate ions The pH of the solution was controlled using three different bases which included tetramethylammonium hydroxide (TMAOH) The precipitated nanoparticles were then evaluated for their surface layer characteristics and were further used for coating via electrophoretic deposition The results revealed that pH was a key factor during synthesis On analyzing the crystalline phases of the nanoparticles it was observed that the choice of pH influenced the formation of different calcium phosphate phases like calcium-deficient hydroxyapatite (CDHA) and carbonate-containing hydroxyapatite (CHA) and a higher calcium to phosphorus (Ca/P) molar ratio The surface of the apatite nanoparticles shows three different layers The inner apatite layer/core is characterized by the presence of the crystalline structure of the apatite Above the apatite layer is the non-apatitic layer which is rich in ions like phosphate ions and carbonate ions This layer reacts with water molecules and forms the hydration layer Analyzing the surface characteristics of these layers revealed that pH adjustments facilitated the formation of the non-apatitic layer rich in reactive ions the study revealed that while higher pH facilitates the formation of the non-apatitic layer the presence of Na+ ions reduces the concentration of phosphate ions leading to decreased reactivity of the layer The introduction of substantial ions by NaOH also affected the uniformity of electrophoretic deposition as observed in scanning probe microscope studies indicating that KOH was more suitable than NaOH for forming the non-apatitic layer and ensuring uniform coating “This study focuses on the critical interfaces between bioceramics and biological systems and could inspire designs of biocompatible surfaces with preferential cell adhesion.” These findings can be potentially useful for surface coating of a wide range of biodevices that are implanted in the human body the team intends to push the boundaries of nanobiomaterials paving the way for groundbreaking innovations in medical materials and devices that could revolutionize healthcare and improve patient outcomes DOI: https://doi.org/10.1021/acsami.4c18645 About Associate Professor Motohiro Tagaya from Nagaoka University of Technology This study was partially supported by a grant from the Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant-in-Aid for Challenging Exploratory Research 10.1021/acsami.4c18645 Surface State Control of Apatite Nanoparticles by pH Adjusters for Highly-Biocompatible Coatings The authors declare no conflicts of interest associated with this manuscript are not responsible for the accuracy of news releases posted to EurekAlert by contributing institutions or for the use of any information through the EurekAlert system Copyright © 2025 by the American Association for the Advancement of Science (AAAS) Rice farmers in Niigata prefecture in Japan are ageing and are not being replaced government and industry are working together to find ways to make agriculture profitable and attractive as a career for young people.Credit: tdub303/E+/Getty More than four centuries of agricultural tradition are at risk of coming to an end in Niigata prefecture in Japan The region is the famed origin of koshihikari rice — one of the most prized varieties in the world due to its sticky texture and sweet flavour But the skilled rice farmers who tend the land are ageing and not being replaced by young people in the prefecture who often choose to live and work in one of Japan’s bustling cities such as Tokyo or Osaka “Almost 60 households in this community used to be farmers: now there are only six,” says Fumikazu Nakamura a 53-year-old farmer who lives near Nagaoka As the farms are terraced and water flows from the mountains through them one farm closing can have knock-on effects on farms lower down a bioengineering professor at Nagaoka University of Technology Koshihikari is the most widely grown rice cultivar in Japan.Credit: lake11/Shutterstock there will only be one or two farms left here in 10 years,” says Nakamura the land will be more and more degraded,” agrees Shigeyuki Osabe whose family farm cultivates rice and also serves as a place for food education for children and tourists Combined with a shrinking and ageing agricultural workforce this creates a vicious cycle that affects the markets of other rice-related industries such as rice confectionery and sake brewing which in turn accelerates the outflow of human resources from Niigata he and his brother both left to pursue careers elsewhere — his brother as a medical doctor and Ogasawara as a researcher specializing in microorganisms he realized a similar situation was happening there and was determined to find a scientific solution to help reinvigorate farming as a career in the region Nagaoka was recognized as one of six so-called ‘biocommunity towns’ as part of a wider government initiative called the Japan Bioeconomy Strategy It brings together 59 organizations including academic institutions with the goal of transforming Nagaoka into a sustainable The average age of the agricultural workforce in Niigata is 69 years.Credit: iryouchin/E+/Getty Building on this is the 10-year KOME-DOKORO (or ‘rice producing region’) COI-NEXT project funded by the Japan Science and Technology Agency which began in 2022 and is led by Ogasawara and Nagaoka University of Technology “It will bring together technologies from various fields at the university to address serious regional issues,” says Shigeharu Kamado the president of Nagaoka University of Technology The project is focused on addressing the critical situation in Niigata’s rice fields government and academia stakeholders with the aim of making agriculture profitable and attractive to young people as well as enabling co-creation across industries and establishing new industries Niigata has the second highest rate of population decline in Japan.Credit: Ryouchin/Stone/Getty The COI-NEXT project has two main targets: establishing sustainable rice production and creating high-value products from unused resources such as waste from rice processing The first target focuses on ways to make rice farming more sustainable “We have a lot of rice fields in streams and mountains,” says Osamu Ikeda “The problem is that the work in these areas is inefficient and yields are low.” the COI-NEXT project is set to transform rice farming in Nagaoka so it is both profitable and attractive to young people “We will co-create future rice fields with farmers and other industries to foster a biocommunity while fully circulating regional bioresources,” explains Ogasawara “We hope this project inspires citizens to see rice fields as their own.” “Now is the time for us to create a future where those who wish to try agriculture are set up well to face the challenge,” says Osabe To learn more about efforts to create a circular bioeconomy in Niigata, please visit KOME-DOKORO COI-NEXT UNAI SDG Hub 9 Chair: Mount Kenya University Mount Kenya University (MKU) is a Chartered ISO 9001:2015 Certified University whose 2020-2029 Strategic Plan focuses on 3 key mandates: teaching The use of industry and institutional partnerships at national continental and international levels is a major hallmark at MKU and is an enabler in achieving the University Mission which is “To provide world-class education research and innovation for global transformation and sustainable development” Thus, MKU is a comprehensive university with diverse range of programmes, activities and infrastructural support that touch on each of the 17 Global Goals including the Maritime Academy at the Kenyan coast which is run on a partnerships-based model Learn more about Mount Kenya University UNAI SDG Hub 9 Vice-Chair for Teaching and Education: La Salle - Ramon Llull University founding member of the Universitat Ramon Llull integrates the Sustainable Development Goals (SDGs) set by the United Nations into its core mission by promoting social innovation La Salle-URL fosters transdisciplinary learning and research aimed at addressing societal challenges  through impactful With a strong focus on responsible AI and community engagement La Salle-URL empowers students and researchers to develop projects that serve people and applied research reflect a deep commitment to ethical leadership and global citizenship reinforcing the university’s role as a changemaker for a fairer and more sustainable future Learn more about La Salle - Ramon Llull University UNAI SDG Hub 9 Vice-Chair for Research: Nagaoka University of Technology Nagaoka University of Technology (NUT) of Japan aims to develop creative abilities based on its educational philosophy the “Science of Technology (GIGAKU),” and fosters both domestic and international students through its core education and research system which is built on a seamless and progressive pathway from Colleges of Technology (KOSEN) to NUT NUT has sent a large number of highly skilled engineers into the world over the years to contribute to the development of industry and infrastructure NUT will continue to strive to cultivate leading engineers with practical and creative abilities who not only drive innovation but are also strongly committed to realizing a sustainable society in line with the SDGs Learn more about Nagaoka University of Technology Learn more about SDG 9 by downloading the SDG 9 Fast Facts and Infographic The Nagaoka MP-200 is a terrific all-rounder and is easily one of the best performers in its class The lack of captive nuts on the cartridge body makes it a little fiddly to fit Nagaoka may not be a familiar name to many readers but this Japanese brand has an impressive and unusual heritage It was formed in 1940 to make precision parts for clocks and watches subsequently going on to specialise in machining fine jewels this led to an expertise in making diamond stylus tips and ultimately Look at the company’s website and you will find it now has fingers in all sorts of pies including headphones alongside manufacturing moving magnet cartridges and various hi-fi accessories The MP-200 moving magnet cartridge is the step-up model in the company’s long-running MP range Unpacking this cartridge sends a wave of nostalgia over us it looks just like the highly-rated MP-11 we craved in the early ’80s this is a significantly more capable cartridge than that much-loved budget favourite Nagaoka recommends a tracking force of between 1.5g - 2.0g and we settled on 1.75g as the best compromise between agility Its talents start with balanced tonality and continue with expressive dynamics and plenty of punch As we work our way through our record collection it is hard not to be impressed by its composure when playing difficult and dense recordings like Orff’s Carmina Burana and its ability to resolve large amounts of information This Nagaoka tracks low-level instrumental strands with ease while still managing to make sense of the whole.  Stereo imaging is crisply focused and nicely layered with the massed choir and instrumentation positioned with conviction and stability This piece is one of the most demanding we know with its savage dynamics and at times almost frenzied orchestration producing a clearer and more precise window into the recording than any price rival we’ve heard with voices coming through in a convincingly natural way as we find out during Four Tet’s There is Love In You set This rich tapestry of electronica shows off the cartridge’s firm grasp of rhythmic drive and its ability to deliver bass with agility The Nagaoka’s presentation is forthright and direct which suits music like this well: this moving magnet isn’t a showy performer and doesn’t embellish the sound to make it more exciting The MP-200 is all about recovering the sound from the record groove without losing the music’s energy and with a minimum of embellishment It is well made and easy to fit (lack of captive nuts aside) There is nothing electrically that puts a hurdle in the way of compatibility and the overall sound is as complete as we have heard at this level We have no choice but to recommend this cartridge highly Read our review of the Goldring 1042 Also consider the Ortofon 2M Black Read our Ortofon Quintet Blue review Best cartridges: budget and premium options for your turntable is the world's leading independent guide to buying and owning hi-fi and home entertainment products Our comprehensive tests help you buy the very best for your money with our advice sections giving you step-by-step information on how to get even more from your music and movies Everything is tested by our dedicated team of in-house reviewers in our custom-built test rooms in London Our coveted five-star rating and Awards are recognised all over the world as the ultimate seal of approval Read more about how we test The NewTon system operates by using ammonia as the primary refrigerant within the machine room while CO2 serves as the secondary refrigerant circulating through the cold storage areas The Nagaoka Logistics Center will have 23,641 metric tons of frozen storage space and 1,174 metric tons of capacity for chilled goods There will be 2,457 metric tons of capacity in the facility’s utility zone the logistics center will use non-fluorocarbon (FCF) insulating materials to avoid emissions that could contribute to global warming or ozone depletion Design details: The new logistics center will span 21,250m2 (228,733ft2) with a total floor area of 21,869m² (235,396ft²) Additional cooling technologies: In addition to the primary refrigeration system the Nagaoka Logistics Center incorporates several advanced cooling technologies to enhance temperature control and ensure the protection of stored goods These technologies work in tandem with the main system to maintain consistent indoor temperatures throughout the facility Cold storage in Japan: Cold storage companies in Japan are increasingly turning to natural refrigerants like ammonia and CO2 to reduce their carbon footprint while maintaining high refrigeration system performance Quotable: “While considering future concepts we were approached by a logistics company about the 2024 problem which highlighted a shortage of collection and distribution points for goods in the Niigata-Hokuriku area,” said Toshio Yoshikawa we decided to focus on Nagaoka to address the lack of refrigerated warehouses in the area.” Europe: (+32) 2 808 90 57United States: (+1) 332 223 4004APAC: (+81) 80 2165 9629 info@naturalrefrigerants.com Lost your password? May 03, 2025 at 11:00am ~ May 04, 2025 at 8:00pm TOKYO M.A.P.S was launched in 2008 as an event to celebrate music, art, and performance in a variety of expressions. This year’s program organizer will be Ryosuke Nagaoka, a vocalist/guitarist for the Petrols and navigator of J-WAVE’s “CITROËN FOURGONNETTE” program. The lineup, curated by Nagaoka, is stacked with original artists including newly announced acts THE BAWDIES and Aya Shimazu. Enjoy this free live full of performances that stimulate the senses. From purple sweet potatoes to wild horse sightings, here’s how to make the most of Okinawa’s tropical escape Explore the best local brands shaping Tokyo’s fashion scene From vintage clothing to Hawaiian-themed goods, here’s what’s worth checking out before it’s gone From buying and registering a bike to key rules of the road Collagen staples for beauty and health in Japan Our handpicked list of the best events going on this month. Love, identity, and the untold tales of Japan’s queer community Everything you need to know before and during a natural disaster Stay up to date with Tokyo news and events 2024One of the world's safest countries offering students top-class facilities across the board Japan is an increasingly popular choice for international students with institutions like Nagaoka University of Technology fostering a culture of innovation Promoting cross-culture collaboration and innovation in the fields of technology and engineering, Nagaoka University of Technology offers a solid educational framework that has allowed its Japanese alumni to succeed overseas while many of its international graduates go on to build successful careers and lives in Japan Given Japan’s demographic issue—with its aging population causing a shortfall in the labor force that is projected to reach 11 million by 2040—preparing international students for the Japanese work place is both a commendable and necessary endeavor led by world-class educational institutions such as Nagaoka University of Technology While international students make up just 5 percent of the overall Japanese student population at Nagaoka University of Technology the figure has reached as high as 13 percent President Kamado Shigeharu attributes this high figure to the university's efforts at building a globally-minded institution and its successful Twinning Program for foreign students while receiving supporting Japanese language classes and have the chance to go on to undertake OTJ (on-the-job) training and complete a master's degree “Sixty-five percent of foreign students find a workplace after completing this program meaning they are working as fully-fledged engineers in Japanese companies,” says President Kamado who also gives some examples of real success stories he mentions a graduate who joined a company in the chemical industry and succeeded in improving efficiency through a product developed in collaboration with a faculty member from the university this graduate has obtained permanent residency and plans to continue their children's education in the country he points to a graduate who completed the master's program and joined an electrical machinery manufacturing company this graduate returned to their home country and secured employment with a foreign company associated with Japan “Our international graduates are not only thriving in Japan but are also making significant contributions worldwide and fostering opportunities for the next generation to receive education in Japan,” adds President Kamado Prepared triaxial apparatus for soil testing Karate practice (club activity) Microstructure analysis with high-resolution SEM Previous Next With students being taught by both Nagaoka and foreign faculty the Twinning Program is a prime example of how the university leverages MOUs (memorandum of understanding) with international institutions for collaborative education programs we are looking to increase the number of MOUs with international universities,” adds President Kamado “We also offer overseas OTJ and bidirectional short-term study abroad programs and conduct overseas staff training to enhance globalization and specialization of our staff we believe that globalization and diversity within the campus are being promoted One of our Japanese graduates who had overseas OTJ experience in a partner company became the president of the firm’s overseas local subsidiary in his 30s His experience not only helped him acquire language skills and expertise in his field but also enabled him to understand culture MOUs with overseas institutions are not just a tool for promoting personal exchanges and collaborative research but are intended to promote collaborative education under the basis of true mutual understanding where both parties are more deeply involved in each other's education.” This enables the cultivation of individuals with diverse perspectives on cultures and values in addition to possessing advanced knowledge and skills “we are seeking partners with whom we will work together to develop engineers in countries and regions where industrial development will accelerate.” One of the world's safest countries offering students top-class facilities across the board Educational institutions like Nagaoka University of Technology foster a culture of innovation ensuring bright futures for their graduates Nagaoka University of Technology offers a solid educational framework that promotes intercultural collaboration and innovation in the fields of technology and engineering with an aging workforce expected to reach 11 million by 2040 preparing international students for the Japanese workplace is a laudable and necessary initiative led by a world-class educational institution such as Nagaoka University of Technology While the percentage of international students in Japan is only 5% of the student body at Nagaoka University of Technology it is 13% President Shigeharu Kamado attributes this high figure to efforts to create a university with a global perspective and the success of the Twinning Program for international students students have the opportunity to take classes in Japanese and receive support in the Japanese language while continuing on to on-the-job training and earning a master's degree "65% of the international students who complete this program are employed and are active as full-fledged engineers in Japanese companies," says President Kamado The first is the example of a graduate who joined a company in the chemical industry and succeeded in improving the efficiency of a product he developed in collaboration with the university's faculty the graduate obtained permanent residency and plans to live in Japan with his family and continue his children's education here The second is a graduate who completed his master's degree and joined an electrical machinery manufacturing company the graduate returned to his home country and got a job at a foreign company with ties to Japan "Our international alumni are not only thriving in Japan but are also making significant contributions globally and fostering educational opportunities in Japan for the next generation," adds President Kamado in which students are taught by both Nagaoka and foreign faculty is a prime example of how the university is leveraging MOUs (memorandum of understanding) with international educational institutions to implement cooperative educational programs we would like to increase the number of MOUs with universities overseas," adds President Kamado and overseas staff training to globalize and enhance the expertise of our staff We believe that these efforts promote globalization and diversity within the university." A Japanese graduate who experienced overseas OTJ at a partner company became president of an overseas subsidiary in his 30s Not only did he acquire language skills and specialized knowledge but he also gained an understanding of culture MOUs with overseas educational institutions are not just a tool to promote personal exchange and joint research but also aim to promote joint education based on true mutual understanding and to have both parties more deeply involved in each other's education." This will foster human resources who have not only advanced knowledge and skills but also diverse cultural views and values and who are capable of generating innovation we are looking for partners to help us train engineers in countries and regions where industrial development is accelerating." industrial and financial news about global economies with a focus on understanding them from within fermented rice that is used in a variety of Japanese dishes at one of Hakkaisan Brewery’s warehouses in Japan.Credit: Hakkaisan Niigata prefecture in Japan is renowned for growing rice Manufacturing these creates a significant amount of unused resources that are rich in carbohydrates and can act as source of nutrients for microbes With the help of microbes involved in fermentation researchers from Japan’s largest rice-producing region are finding ways to transform these unused resources into useful products such as food microorganisms could produce enzymes and surfactants for detergents needed for cleaning allowing even factory effluent to be repurposed for compost and other uses they aim to achieve a dual-benefit technological advancement that realizes both the recycling of local resources and economic growth To maximize the power of microbes and apply them to bio-manufacturing Akihiro Nakamura and his team at Nagaoka University of Technology are working with nine universities to discover new microorganisms capable of producing useful substances and finding ways to make them better fermenters They are also developing real-time monitoring techniques to ensure that these microbes will help contribute to improved productivity of industrial fermentation activities This effort forms part of the KOME-DOKORO or ‘rice producing region’ COI-NEXT project which aims to create a ‘circular’ bioeconomy in Niigata’s KOME-DOKORO region led by Wataru Ogasawara at Nagaoka University of Technology The project is funded by the Japan Science and Technology Agency (JST) one of the companies working with Nakamura’s team is renowned for its expertise in fermentation processes rice-derived fermented beverage called koji amasake The Niigata-based brewery uses tonnes of water every day to ‘polish’ rice as part of the sake production process head of Hakkaisan’s research and development department says it poses a significant environmental burden The rice washing wastewater contains large complex molecules such as these need to be broken down and used as raw material for useful products This is where microorganisms come into the picture but as they are difficult to isolate and culture as few as 1% have been identified as useful resources His team is working to isolate microorganisms with high fermentation capabilities using a powerful tool called the Million Screening Technology developed with other Japanese collaborators1 Their ultimate aim is to both identify and enhance the breeding of these microorganisms so they may be used to produce high-value added products necessary for fermentation The Million Screening Technology can screen a million individual microorganisms just in a few days compared to conventional methods that use labour-intensive agar-based medium or microtiter plates and require a few months to complete Nakamura and his team have been working to strengthen and improve this Million Screening Technology for ultra-high-throughput screening to isolate difficult-to-cultivate microorganisms and candidate strains of new microorganisms from environmental samples researchers encapsulate microorganisms in 100-micrometre-wide droplets of water which are placed in an oil-based emulsion for culturing But the downside is that a common fluorescent probe called 7-amino-4-methylcoumarin (AMC) which is used to detect protease and peptidase — the enzymes used for non-chemical detergent — often leaks from the water droplets into the oil phase making enzyme activity detection difficult and limiting the scope of the assay for detecting certain bacteria Using AMC as a model, Nakamura’s team synthesized a fluorogenic compound called ‘aminocoumarin-4-acetic acid’, which they found was retained in the droplets for more than seven days and could help detect enzyme activity derived from microorganisms1 He explains that being able to efficiently detect enzyme activity from microorganisms during screening is a step towards commercially viable production of eco-friendly detergents from rice-related resources as a replacement of chemical detergents Nakamura’s team are now investigating if the new microorganisms acquired with their Million Screening Technology can effectively break down the unused resources from rice such as rice washing wastewater and produce high value-added products collaborating with rice-related companies such as Hakkaisan Brewery “We are delighted to be part of the COI-NEXT project to work together and create a pioneering model of resource circulation,” The team also set out to create a system for real-time monitoring of microorganisms cultured in a large-scale jar fermenter with the hope that it may be scaled up to help improve productivity for industrial fermentation production While in other applications sensors are used to measure key indicators such as dissolved oxygen and pH Nakamura explains the culturing environment is too complex and these approaches cannot determine the physiological states of microorganisms to a sufficient level for a Toji or a sake master brewer “We focus on the shape of the microorganisms because their morphological changes can tell us about the fermentation status and their growth conditions,” he says we aim to control the microbial cultivation and achieve a high yield of useful bioresources.” One of Hakkaisan Brewery’s warehouses in Niigata As a first step, Nakamura and his colleagues developed a system equipped with a microfluidic chip and an ultra-high-speed camera to observe an ethanol-producing yeast2 The culture medium flowed from the jar fermenter across the microfluidic device with the camera taking more than 10,000 images of microorganisms every 2.2 seconds for more than 168 hours Having analysed 33,600 of the nearly 1.7 million resultant images the researchers indicated the correlations between three physical parameters — long axis short axis and cell area — and the changes in the yeast’s ethanol production over time The team then reported an upgraded version of the system by incorporating deep learning technologies, which helped them to analyse how the physical changes of oleaginous yeasts are linked with their oil productivity3 Some of these yeasts can accumulate abundant lipids in their cells and are considered a promising bioresource because they can produce oil we manually analysed two terabytes worth of high-definition cell images but this time we created deep-learning algorithms from scratch,” Nakamura explains The team trained the algorithms to automatically extract the non-blurred yeast cells and then to classify the shapes The cell images were grouped into seven categories which suggested strong correlations between each group and its biochemical activities such as the cell growth and a target product “Our technology can be used to determine if the cultivation is going well and if productivity is being properly achieved,” says Nakamura adding that possible future applications include the observation of the fermentation state of sake and other rice-derived resources With the help of such advances in microbe screening and culturing techniques and real-time monitoring for continual productivity improvement that Nakamura and his team are developing along with input from industry partners such as Hakkaisan Brewery this COI-NEXT project is set to create new industries by transforming unused resources from rice into high value-added products Download references Metrics details An Author Correction to this article was published on 12 March 2025 This article has been updated Prices may be subject to local taxes which are calculated during checkout The datasets generated and analysed during this study are available from the corresponding author on reasonable request. Source data are provided with this paper The codes used for the analysis are available from the corresponding author on reasonable request A Correction to this paper has been published: https://doi.org/10.1038/s41586-025-08819-0 Interacting Electrons and Quantum Magnetism (Springer Exchange in solid 3He and the Heisenberg Hamiltonian Extension of Nagaoka’s theorem on the large-U Hubbard model Instability of the Nagaoka ferromagnetic state of the U = ∞ Hubbard model Density matrix renormalization group analysis of the Nagaoka polaron in the two-dimensional t − J model Kinetic antiferromagnetism in the triangular lattice Resonating valence bonds: a new kind of insulator? Doping a Mott insulator: physics of high-temperature superconductivity Instability of the Nagaoka state with more than one hole Holes in the infinite-U Hubbard model: instability of the Nagaoka state Stability of the ferromagnetic state with respect to a single spin flip: variational calculations for the U = ∞ Hubbard model on the square lattice Stability of the saturated ferromagnetic state in the one-band Hubbard model Ferromagnetism in the Hubbard model: instability of the Nagaoka state on the triangular Ferromagnetism in the Hubbard model on the square lattice: Improved instability criterion for the Nagaoka state Dynamical mean-field theory study of Nagaoka ferromagnetism Phases of the infinite U Hubbard model on square lattices Doped Mott insulators in the triangular-lattice Hubbard model Nagaoka ferromagnetism observed in a quantum dot plaquette Simulation of Hubbard model physics in WSe2/WS2 moiré superlattices Kinetic magnetism in triangular moiré materials Frustration- and doping-induced magnetism in a Fermi–Hubbard simulator Quantum simulation of frustrated classical magnetism in triangular optical lattices Single-site-resolved imaging of ultracold atoms in a triangular optical lattice Site-resolved imaging of ultracold fermions in a triangular-lattice quantum gas microscope Quantum gas microscopy of fermionic triangular-lattice Mott insulators Design and construction of a quantum matter synthesizer Pairing from strong repulsion in triangular lattice Hubbard model Holes and magnetic polarons in a triangular lattice antiferromagnet Itinerant spin polaron and metallic ferromagnetism in semiconductor moiré superlattices Proposal for asymmetric photoemission and tunneling spectroscopies in quantum simulators of the triangular-lattice Fermi-Hubbard model Morera, I., Weitenberg, C., Sengstock, K. & Demler, E. Exploring kinetically induced bound states in triangular lattices with ultracold atoms: spectroscopic approach. Preprint at https://arxiv.org/abs/2312.00768 (2023) High-temperature kinetic magnetism in triangular lattices Schlömer, H., Schollwöck, U., Bohrdt, A. & Grusdt, F. Kinetic-to-magnetic frustration crossover and linear confinement in the doped triangular t − J model. Preprint at https://arxiv.org/abs/2305.02342 (2023) Samajdar, R. & Bhatt, R. N. Nagaoka ferromagnetism in doped Hubbard models in optical lattices. Preprint at https://arxiv.org/abs/2305.05683 (2023) Single-particle excitations in magnetic insulators Two-particle excitations in antiferromagnetic insulators Parton theory of magnetic polarons: mesonic resonances and signatures in dynamics Imaging magnetic polarons in the doped Fermi–Hubbard model Coupling a mobile hole to an antiferromagnetic spin background: transient dynamics of a magnetic polaron Microscopic evolution of doped Mott insulators from polaronic metal to Fermi liquid Prichard, M. L. et al. Directly imaging spin polarons in a kinetically frustrated Hubbard system. Nature https://doi.org/10.1038/s41586-024-07356-6 (2024) Myriad phases of the checkerboard Hubbard model Classical antiferromagnetism in kinetically frustrated electronic models Polaron percolation in diluted magnetic semiconductors Chiral spin liquid phase of the triangular lattice Hubbard model: a density matrix renormalization group study Magnetism and superconductivity of strongly correlated electrons on the triangular lattice Doping the chiral spin liquid: topological superconductor or chiral metal Morera, I. & Demler, E. Itinerant magnetism and magnetic polarons in the triangular lattice Hubbard model. Preprint at https://arxiv.org/abs/2402.14074 (2024) Morera, I., Bohrdt, A., Ho, W. W. & Demler, E. Attraction from frustration in ladder systems. Preprint at https://arxiv.org/abs/2106.09600 (2021) Tunable spin and valley excitations of correlated insulators in γ-valley moiré bands Tao, Z. et al. Observation of spin polarons in a frustrated moiré Hubbard system. Nat. Phys. https://doi.org/10.1038/s41567-024-02434-y (2024) Spin-bag mechanism of high-temperature superconductivity On Next-Nearest-Neighbor Interaction in Linear Chain A quantum gas microscope for detecting single atoms in a Hubbard-regime optical lattice Site-resolved measurement of the spin-correlation function in the Fermi-Hubbard model Thermodynamics of strongly interacting fermions in two-dimensional optical lattices Precise characterization of 6Li Feshbach resonances using trap-sideband-resolved RF spectroscopy of weakly bound molecules Magnetically mediated hole pairing in fermionic ladders of ultracold atoms Strong pairing in mixed-dimensional bilayer antiferromagnetic Mott insulators An iteration method for the solution of the eigenvalue problem of linear differential and integral operators Schrieffer-Wolff transformations for experiments: dynamically suppressing virtual doublon-hole excitations in a Fermi-Hubbard simulator Methods of Quantum Field Theory in Statistical Physics (Pergamon Determinant diagrammatic monte carlo algorithm in the thermodynamic limit Quantum monte carlo study of the two-dimensional fermion hubbard model Numerical linked-cluster approach to quantum lattice models A short introduction to numerical linked-cluster expansions Hauschild, J. & Pollmann, F. Efficient numerical simulations with tensor networks: Tensor Network Python (TeNPy). SciPost Phys. Lect. Notes https://doi.org/10.21468/SciPostPhysLectNotes.5 (2018) Download references We acknowledge support from the Gordon and Betty Moore Foundation GBMF-11521; the National Science Foundation (NSF) acknowledges support from the Swiss National Science Foundation (SNSF) and the Max Planck/Harvard Research Center for Quantum Optics acknowledge support from the NSF Graduate Research Fellowship Program acknowledges support from the AWS Generation Q Fund at the Harvard Quantum Initiative PID2020-114626GB-I00 from the MICIN/AEI/10.13039/501100011033 Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya cofunded by the European Union Regional Development Fund within the ERDF Operational Program of Catalunya (project no acknowledge support from the NSF under grant no acknowledge support from the SNSF project 200021_212899 and the NCCR SPIN of the SNSF NLCE calculations were done on the Spartan high-performance computing facility at San José State University These authors contributed equally: Martin Lebrat Departament de Física Quàntica i Astrofísica performed the experiment and analysed the data The numerical simulations were performed by M.X All authors contributed to the interpretation of the results and production of the paper is the co-founder and shareholder of QuEra Computing Jae-yoon Choi and Zheng Zhu for their contribution to the peer review of this work Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations A degenerate Fermi gas is loaded into a lattice formed by beams X and Y with a linear ramp of the lattice power The lattice power is quenched to freeze tunneling Radiofrequency Landau-Zener transfers are used in some shots to change the spin states on singly-occupied sites Handing off from X + Y to \(\bar{X}+Y\) adiabatically doubles the unit cell converting doubly-occupied sites to pairs of singly-occupied sites Atoms are handed off to a separate imaging lattice where a resonant laser is used in some shots to selectively remove one spin state Numerical simulation (FTLM) of the nearest-neighbour non-normalized spin-spin and hole-spin-spin (doublon-spin-spin) correlation functions in a 4 × 3t − J cluster as a function of doping δ and gradient strength Δ We compute the connected doublon-spin-spin correlation function a with NLCE at U/t = 72 and T/t = 0.52729; e Definition of bonds averaged together in NLCE simulations Bonds beyond fifth nearest-neighbor are not computed and set to zero in the plot Connected doublon-spin-spin correlator as a function of interaction strength, obtained from NLCE simulations at T/t = 0.7; a, at half-filling and b, at particle doping δ = 0.05. See Fig. 2 for a definition of the correlators The U/t = 0 numerics are computed using Wick’s contraction The errors in FTLM and DQMC are statistical while in DMRG they indicate the spatial variation of the correlators over the simulated system DMRG simulation of the net total spin 〈S〉 normalized by maximal spin as a function of doping δ showing the emergence of long-range ferromagnetism with doublon doping Spectrum of the Hubbard Hamiltonian on a triangular plaquette Eigenenergies are shown as a function of interaction strength U/t for one particle dopant (left) and one hole dopant (right) Labels show the nature of the state at infinite interaction U/t = ±∞ (S: singlet; T: triplet; H: one hole; D: one doublon) and its angular momentum ℓ = 0 Colors indicate the sign and magnitude of the spin correlations a, Doublon-spin-spin and b, hole-spin-spin correlation function on a triangular plaquette without normalization factor, see Eq. (8) for definition and Fig. 3 for details a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law Download citation DOI: https://doi.org/10.1038/s41586-024-07272-9 Anyone you share the following link with will be able to read this content: a shareable link is not currently available for this article Sign up for the Nature Briefing newsletter — what matters in science this fun and exciting Sumiko cartridge is an affordable A well-priced moving coil cartridge that thrives on detail The moving magnet Vertere Sabre cartridge is your go-to easy-to-fit cartridge with plenty of personality Essential and easy upgrade for your record player If your turntable setup is in need of a refresh it's worth considering changing the current cartridge rather than swapping out the entire record player itself and you might find yourself listening to your record collection with fresh ears thanks to a new Cartridges come in two types: moving magnet and moving coil Moving magnet (MM) cartridges have a cantilever which transfers mechanical vibrations picked up from the record groove straight into movements of the cartridge's magnet This movement of the magnet relative to the nearby wire coils induces current in those coils which is then amplified and turned back into sound by the speakers your amplifier will need an MM phono input to boost and equalise the low-voltage signal or simply scroll down to see our top picks refined and expressive manner working with most affordable turntables Read more below dynamic and musically cohesive cartridge that will lift your spirits and the performance of your turntable Read more below this is great value for an affordable moving coil model and needs a suitably talented phono stage to shine Read more below but it's an incredibly fun performer that balanced energy and rhythmic prowess with fantastic insight and control Pair with a premium deck and you'll never stop dancing Read more below composed and entertaining MC cartridge that's worth every penny of its high asking price Read more below Top tipKetan BharadiaTechnical editorI have been reviewing hi-fi products and have been using record players for even longer than that I've listened to (and changed) a variety of cartridges across the price range in my time and have heard all of the cartridges recommended in this guide with a variety of turntables too I am confident you'll find a cartridge to suit your deck and needs and I would always recommend demoing a new cartridge combination where possible especially when looking at higher-end options This impressive Goldring E3 is a cinch to fit and is compatible with plenty of turntables making it a very versatile cartridge indeed with plenty of clarity and power where required The perfect accompaniment to many a midrange deck and easily one of the best cartridges we've heard at the affordable end of the price scale Read the full Goldring E3 review Sumiko knows plenty about cartridge manufacturing The company was founded in 1982 and continues to build all of its cartridges in Japan to this day The Rainier moving magnet sits at the more affordable end of the company’s Oyster range and looks to be a good choice for those itching for that first upgrade to their turntable This Sumiko is a thoughtful design that’s easy to fit thanks to captive nuts inset into the body and sensibly squared-off edges that make fitting and alignment a breeze Once up and running it's a surprisingly musical and engaging performer but it’s more the cohesive way that the Rainier delivers all that information that makes it special We hear plenty of punch and a great dose of dynamics when it's required Read the full Sumiko Rainier review Ortofon has been making turntable cartridges since 1948 and it seems like all its expertise went into this one The Quintet Blue moving coil is a true five-star product: simple to fit and capable of a sound that's worth every penny of its asking price with a high level of sonic precision that's brimming with detail and it's rhythmically surefooted with a good sense of attack Just make sure you partner it with the right kit otherwise it'll be like fitting pram wheels to a Ferrari A strong alternative at this price is the Nagaoka MP-200 – it's a moving magnet rather than a moving coil but is a terrific all-rounder that is worthy of consideration Read the full Ortofon Quintet Blue review The Sabre moving magnet is a carefully considered design as we’ve come to expect from Vertere That bold orange body isn’t just for show It’s machined out of a solid block of aluminium for rigidity and clamps onto the generator structure with four bolts rather than being glued on performance and alignment grounds The cartridge body’s top is raised at three points to ensure a solid and even contact with the headshell and the front of the top even has a ridge to aid easy alignment The result is a bold performer that's confident without being in any way overbearing Listening to Orff’s rambunctious Carmina Burana we can’t help but be thrilled by the energy and drive of the music We said in our review: "The Sabre delivers this dramatic piece with all the gusto it demands We get explosive dynamic peaks coupled with an impressive sense of control." While the Sabre's high £845 / $1199 / AU$1695 price puts it deep into traditional moving coil territory this is one premium moving magnet we can really get behind Read the full Vertere Sabre MM review The Pick-it DS2's body is made of a synthetic polymer and shaped by laser in a bid to create a low-resonance base and help performance The sound is thoroughly robust and dynamically expressive and there's a ton of detail to get your teeth into Read the full Pro-Ject Pick-it DS2 review it’s worth asking the dealer to set it up for you There are two types of cartridges – moving magnet and moving coil – and which type you go for will depend on the level (both in price and quality) of the rest of your system it's best to stick with moving magnet (MM) cartridges the partnering amplifier and phono stage can be of varying quality and a moving magnet will put less of a spotlight on your phono stage's quality because it has a higher output If your turntable is at about £1500 and above then it's worth looking into moving coil (MC) cartridges the partnering phono stage and amplifier in your system will need to be of a certain higher quality level too and you will reap the rewards of an MC cartridge more in this context Many standalone phono stages and amplifiers (or streaming systems) with phono stages built in will quite often support both cartridge types it's worth bearing in mind that even if a budget phono stage can support MC cartridges it may not be worth investing as it likely won't be of good quality to show the benefits Your phono stage has to be of a certain quality (and therefore higher price point) for the advantages of the higher-priced MC cartridges to be apparent in your system you don't necessarily have to match turntable and cartridge brands but many manufacturers that design their own cartridges (e.g Vertere) tune them to match their own turntables But there are plenty of cartridge makers whose models can be used with any turntable especially when you get to high-end models – just make sure you read up on reviews (such as ours of course) to ensure the sonic characteristics will match has been reviewing turntables and cartridges of all types and across budgets since the magazine started in 1976 and we are proud to do all our testing in-house We have state-of-the-art and acoustically treated testing facilities in London and Reading where our team of experienced reviewers test everything from TVs to turntables and we do our best to review as many new models in as many markets as possible to ensure our contextual knowledge is the best it can be All review verdicts are agreed upon by the team as a whole rather than an individual reviewer to eliminate any personal preference and bias and to make sure we're being as thorough as possible There's no input from PR companies or our sales team when it comes to the verdict You can read more about how we test and review products on What Hi-Fi? here You may not be able to find the page you were after because of: You might find one of the following links useful: Discover how ATLANT 3D's DALP technology revolutionizes thin-film deposition enabling rapid prototyping and advanced material applications in nanofabrication Precise Nano Corporation is transforming nanogold production with innovative methods that ensure purity Ramakrishna shares his insights into his ongoing electrospinning work and highlights nanofibers' transformative potential in addressing critical challenges InProcess' FIDES is the perfect tool for nanoparticle size characterization for turbid sample analysis The Leica EM VCT500 Vacuum Cryo Transfer System can transfer samples under cryogenic conditions or at room temperature The CT-2 is an ultra-thin vibration isolation platform with superior stability and easy setup you can trust me to find commercial scientific answers from AZoNetwork.com please log into your AZoProfile account first Registered members can chat with Azthena, request quotations, download pdf's, brochures and subscribe to our related newsletter content A few things you need to know before we start Read the full Terms & Conditions. Owned and operated by AZoNetwork, © 2000-2025 Nagaoka Fireworks festival in Niigata is one of the country’s largest, most visited fireworks celebrations. Over 20,000 explosions paint the  sky across the two-day event, which draws visitors from far and wide. The festival started in its current iteration in 1947, to commemorate victims of some intense bombing during World War II. It’s continued in some form ever since, growing year on year to its current impressive state. Please enable JS and disable any ad blocker We conducted muscle synergy and gait analyses in a monoplegic patient whose gait function improved through training, to explore the possibility of using these parameters as indicators of training. A 49-year-old male had monoplegia of the right lower limb caused by infarction of the left paracentral lobule. After 2 months of training, he was able to walk and returned to work. Consecutive analyses were done after admission. Muscle synergy analysis: during walking, surface electromyograms of gluteus maximus, quadriceps femoris, adductor femoris, hamstrings, tibialis anterior, medial/lateral gastrocnemius, and soleus on both sides were recorded and processed for non-negative matrix factorization (NNMF) analysis. Gait analysis: markers were placed at foot, and walking movements were video recorded as changes in position of the markers. Volume 17 - 2023 | https://doi.org/10.3389/fnhum.2023.1287675 Purpose: We conducted muscle synergy and gait analyses in a monoplegic patient whose gait function improved through training to explore the possibility of using these parameters as indicators of training Case presentation: A 49-year-old male had monoplegia of the right lower limb caused by infarction of the left paracentral lobule Methods: Consecutive analyses were done after admission surface electromyograms of gluteus maximus and soleus on both sides were recorded and processed for non-negative matrix factorization (NNMF) analysis Gait analysis: markers were placed at foot and walking movements were video recorded as changes in position of the markers Results: Compared with three muscle synergies detected on the non-paretic side two muscle synergies were extracted on the paretic side at admission and the number increased to three and then four with progress in rehabilitation training Changes in weighting and activity of the muscle synergies were greater on the non-paretic side than on the paretic side the knee joint flexor and the ankle dorsiflexor activities on the paretic side and the gluteus maximus activity on the non-paretic side increased during swing phase as shown by weight changes of muscle synergies and gait analysis showed increased knee joint flexion and ankle joint dorsiflexion during swing phase in the paretic limb variability of muscle activity was observed and three or four muscle synergies were extracted depending on the number of strides analyzed Conclusion: The number of muscle synergies is considered to contribute to motor control Rehabilitation training improves gait by increasing the number of muscle synergies on the paretic side and changing the weights of the muscles constituting the muscle synergies we propose the existence of compensatory mechanisms also on the non-paretic side the number of strides used in each analysis set has to be examined This report highlights the issues of NNMF as analytical methods in gait training for stroke patients but did not directly propose functional training methods there are few methods using conventional EMG recording which provide feedback of the results during training in the clinical setting The availability of visible indicators that can be analyzed within a short time and are fed back during training will allow implementation of more effective rehabilitation there are some debates on the methodology of muscle synergy analysis such as the filters used to process surface EMG and the type of dataset (averaged or concatenated) we investigated the neural mechanisms involved in gait by performing muscle synergy analysis in a patient with focal infarction in the cerebral cortex of the frontal lobe (paracentral lobule) and analyzing the recovery process of lower limb paresis A 49-year-old male had right lower limb monoplegia caused by focal infarction of the left paracentral lobule. The patient was unable to voluntarily contract the distal muscles of the right lower limb, although he was capable of unsteady gait. While he apparently walked as automatic movements, he was not able to contract individual lower limb muscles. This case was previously reported as a case of automatic-voluntary dissociation (Nagaoka et al., 2022) Although lower limb tendon reflexes were reduced at admission the reflexes increased mildly during hospitalization After approximately 2 months of rehabilitation training although he remained incapable of voluntarily contracting individual lower limb distal muscles (triceps surae his stride length improved from 986.3 to 1,456.6 mm and cadence from 92.4 to 105.6 steps/min he was discharged from the hospital and subsequently returned to his former job Clinical course from onset of stroke to discharge and details of assessments and training heel strike was visually determined for each gait cycle (comprising heel strike Number of strides analyzed and filter used in selected reports Methods of electromyographic (EMG) analysis (A) EMG recordings while the patient was walking (3 km/h) on a treadmill just before discharge from hospital one stride was demarcated as the segment from one heel strike (dotted line) to the next heel strike (dotted line) (B) Results of root-mean-square (RMS) calculated from the raw EMG data for the tibialis anterior (TA) and medial gastrocnemius (GMed) from the first to fourth stride on the non-paretic (left) side (C) Results of resampling varied amounts of data with stride times ranging from 1.19 to 1.25 s/strike uniformly into 100 data The RMS data in the middle panels (B) show the data of time (seconds) taken by each stride sampled at 2,000 Hz while the data in the lower panels (C) show the data resampled to 100 (X-axis of first stride in C: 0 to 100) Amplitude is normalized by setting the maximum value for each muscle to 100 Although fine changes in the waveform are seen in the RMS data these fine fluctuations have disappeared after resampling after applying a high-cut (low-pass) filter Results of non-negative matrix factorization (NNMF) analysis of the non-paretic side Numbers in the weight plots (B) represent different muscles the names of which are shown in the table in the lowest row the four muscle synergies observed on the non-paretic side are considered to be the basic model Syn-1 shows increased activity during late stance phase and the triceps surae is strongly involved Syn-2 shows increased activity in the first half of stance phase and at the next heel strike and lower limb proximal muscles are strongly involved Syn-3 shows increased activity in early swing phase and the tibialis anterior is prominently involved Syn-4 shows increased activity in late swing phase and the hamstrings are mainly involved the third muscle synthesis is Syn-3 or Syn-3 + 4 (a pattern showing integration of Syn-3 and Syn-4) and that of Syn-3 and Syn-4 may be reversed Relationship between the number of strides analyzed and the number of muscle synergies extracted Results of analyses of treadmill walking just before discharge A recording of 60 strides during walking at 3 km/h was available the initial four strides from 1 to 4 were first analyzed followed by the next four strides from 2 to 5 first from 1 to 20 followed by 2 to 21 steps regardless of the number of strides analyzed (4 three muscle synergies were observed in the analysis using 20 strides except at the beginning of walking (top row) When the number of strides analyzed was gradually reduced to 16 four muscle synergies were observed at increasing frequencies four muscle synergies were observed in the first half of the 60-stride walk and then shifted to three muscle synergies at around the middle of the walk (bottom row) (A) Angle between planta and floor surface and ankle joint angle were calculated by the changes in marker position during flat floor walking Markers were placed on the head of fibula (B) the lower end (D) of the lateral malleolus (C) and the head of the fifth metatarsal bone (E) (B) We measured kinematics three times during hospitalization Here we present the initial and the last measurements plantar angle was increased four times compared with that on admission This angular change was probably due mainly to the increased knee joint flexion The ankle joint dorsiflexed about 20 degrees at the terminal swing phase at discharge compared to about 8 degrees of plantar flexion before intervention To precisely compare the changes in kinematics we measured under the same condition of barefoot walking Angle (X) is calculated by the following equation: X (degree) = arcsin [difference (mm) in height between D and E/distance (mm) between D and E] The positions of marker B The length of the foot between D and E was Dist (mm) Xn = arcsin[(D(yn)-E(yn))/Dist] The ankle joint angle (θ) is calculated by the following equations: CB→ = vector[B(xn)-C(xn) B(yn)-C(yn)] = a→ CE→ = vector[E(xn)-C(xn) E(yn)-C(yn)] = b→ a→ • b→=|a→| |b→| cosθ: Inner product of vector a and b θ = arccos[a→ • b→/|a→| |b→|] Angle (X) between planta pedis and floor surface is calculated by the following equation: X (degree) = arcsin [difference (mm) in height between D and E/distance (mm) between D and E] The ankle joint angle (θ) is calculated by the following equations: a→ • b→=|a→| |b→| cosθ: Inner product of vector a and b θ = arccos[a→ • b→/|a→| |b→|] The data were recorded with an iPhone and analyzed using the motion analysis software Kinovea ver. 0.8.27.3 The kinematic analyses were done three times (Table 1) After approximately 75 days of in-hospital rehabilitation training, the patient’s walking stability and endurance improved, and he was discharged from the hospital and subsequently returned to his former job. However, he exhibited automatic-voluntary dissociation and remained unable to voluntarily contract individual lower limb muscles, especially the tibialis anterior and triceps surae (Table 1) We confirmed that the typical composition of the four patterns of muscle synergies obtained by our method was similar to previous reports (Clark et al., 2010; Chujo et al., 2022) The naming and characteristics of the muscle synergies are described below: Synergy-1 (Syn-1): The activity profile showed that the activity of this synergy increased during late stance phase and muscle weighting plot showed that the triceps surae was primarily involved activity increased in initial stance phase and at the next heel strike Weighting showed that the lower limb proximal muscles (gluteus maximus activity increased in initial and terminal swing phase and the tibialis anterior was predominantly involved The characteristics of Syn-1 and Syn-2 did not differ irrespective of whether three or four muscle synergies were detected but the order of Syn-1 and Syn-2 or that of Syn-3 and Syn-4 was reversed in some analyses In some analyses with three muscle synergies Syn-3 showed a pattern resembling a combination of Syn-3 and Syn-4 seen in analyses with four muscle synergies; this pattern of muscle synergy was named Synergy-3 + 4 (Syn-3 + 4) and adductor (3); although the proximal muscles such as hamstrings (4) the gluteus maximus (1) and tibialis anterior (5) were primarily involved Figure 5. Surface electromyographic (EMG) recordings during walking on the flat floor at 10 days after admission. (A) EMG recordings of walking on the floor of the rehabilitation room (Nagaoka et al., 2022) despite the difficulties to voluntarily contract individual muscles muscle activities consistent with the rhythm of walking are recorded on the paretic (right) side although the interference waveforms are inferior to those recorded on the non-paretic (left) side The NNMF analysis extracts two muscle synergies on the paretic side and three on the non-paretic side and it is possible to explain the original waveform with a probability over 90% (B) Results of NNMF analysis of the paretic side The plots at the far right show the activities in one gait cycle Two muscle synergies; Syn-1 activated in stance phase (first 50% of the gait cycle) and Syn-2 activated in swing phase the weights of muscles involved in muscle synergies are high for gluteus maximus (labeled 1 on X-axis) quadriceps femoris (2) and adductor (3); but hamstrings (4) medial gastrocnemius (7) and soleus (8) are also involved gluteus maximus (1) and tibialis anterior (5) are prominently involved (C) Results of NNMF analysis of the non-paretic side Syn-1 with increased activity in early stance and at the next heel strike and Syn-3 with high activity in swing phase are extracted As for the weighting of muscles involved in synergy high involvement is observed for triceps surae in Syn-1 and tibialis anterior and hamstrings in Syn-3 The NNMF analysis of the non-paretic side extracted Syn-1 with high activity in late stance phase, Syn-2 with increased activity in early stance phase and at the next heel strike, and Syn-3 + 4 showing high activity in swing phase (Figure 5C) From the weighting data of the non-paretic side the muscles prominently involved were the triceps surae in Syn-1 and the tibialis anterior and hamstrings in Syn-3 These findings were consistent with the typical patterns reported previously particularly in quadriceps femoris and tibialis anterior Results of analyses of the paretic (right) side during rehabilitation training (54 days after admission) (A) Shows the analysis in which three muscle synergies are detected From the recordings of activities shown on the far right Syn-1 involving the lower limb extensor muscles in later half of stance phase Syn-3 involving the tibialis anterior in early swing phase and Syn-2 involving the lower limb proximal muscles in early stance phase and at the next heel strike are observed (B) Shows the analysis in which four muscle synergies are detected Syn-1 involving the lower limb extensor muscles in late stance phase Syn-2 involving the femoris muscle group in early stance phase Syn-4 involving the hamstrings in late swing phase can be discriminated After approximately 2 months of in-hospital training, the patient was able to walk outdoors independently, but he decided to use an AFO to improve endurance in preparation for returning to his former job that involves working mainly in a standing position. In this stage, the results of muscle synergy analysis conducted without wearing orthosis yielded mainly four muscle synergies on the paretic side (Figure 7) and three or four muscle synergies on the non-paretic side Comparison of stabilities of muscle synergies between paretic and non-paretic side recorded before discharge (72 days after admission) The weighting and activity data of the muscles constituting the four synergies on the paretic side (A) as well as four or three synergies on the non-paretic side (B,C) are expressed in mean and standard deviation The standard deviations are small on the paretic side the standard deviations of Syn-1 and Syn-2 are small The number of samples of the paretic side was n = 13 and the numbers of the non-paretic side were n = 9 for four-synergy analysis Figure 9. Changes in number of muscle synergies during the course of rehabilitation training: analyses using 4 strides. Measurements were performed four times during the hospital stay: (1) 10 days after admission (18 strides), (2) 24 days after admission (20 strides), (3) 54 days after admission (32 strides), and (4) 72 days after admission (before discharge) (60 strides). Unlike the method in Figure 3 calculation was performed for each group of 4 consecutive steps without overlapping and the results of 15 analysis sets are plotted the paretic side shows two synergies using 8 strides The frequency of detecting four synergies increases during the course of training with 13 of 15 analyses extracting four synergies at the time of discharge the non-paretic side shows three synergies initially and the frequency of detecting four synergies increases over time with 9 of 15 analyses yielding four synergies before discharge On the non-paretic side, the number of muscle synergies extracted differed depending on the number of strides (number of samples) analyzed. Three muscle synergies were extracted when using 12 or 8 strides in one analysis set, while three muscle synergies were extracted in some analyses and four in others when using 4 strides (Figure 9) At the start of training, three muscle synergies were observed in analyses using 4 strides (two muscle synergies extracted in analyses using 8 strides). As gait improved, the number of analyses showing three muscle synergies decreased, and the number of analyses showing four muscle synergies increased (Figure 9) The characteristics of the muscle synergies obtained in the course of recovery were not the same as the four stable patterns observed just before discharge At the start of training, three muscle synergies were detected on the non-paretic side (left), comprising Syn-1 involving the triceps surae activated in late stance phase, Syn-2 involving left lower limb proximal muscles activated in early stance phase and at the next heel strike, and Syn-3 + 4 involving the hamstrings and tibialis anterior (Figure 5C) Distribution of stride time in non-paretic (left) lower limb When analysis was conducted using 4 strides the results of 15 analysis sets were obtained The distribution and mean (*) stride time of the four strides used in each analysis extracting three () or four synergies () are plotted four muscle synergies were extracted on the paretic side and the weights of the muscles involved in activation of the muscle synergies were less variable compared with the non-paretic side The patient used an AFO during the course of rehabilitation training. Although an AFO can be expected to assist ankle dorsiflexion controlled by the tibialis anterior during early swing phase, the analysis conducted 24 days after admission showed that wearing an AFO exerted no significant effect on the tibialis anterior muscle activity during the gait cycle (Figure 11) Effect of wearing ankle-foot orthosis: analysis of the paretic side 24 days after admission EMG recording of right gluteus maximus was missing in this measurement NNMF was done on seven muscles excluding gluteus maximus The patient performed treadmill walking barefoot but wearing an ankle-foot orthosis on the paretic side three muscle synergies are detected on the paretic side: Syn-1 with prominent activity of lower limb proximal muscles Syn-2 with prominent activity of triceps surae and Syn-3 with activity of tibialis anterior in early swing phase No significant changes are observed with the use of an ankle-foot orthosis consequently changing the weights of the muscles that constitute the muscle synergies while gait analysis confirmed that the training increased knee joint flexion during the swing phase in the paretic lower limb As Syn-3 was developed as training progressed, we expected the ankle joint to dorsiflex during the swing phase. At discharge, the ankle joint dorsiflexed about 20 degrees at the terminal swing phase (Figure 4B, bottom right), compared to plantar flexion of about 8 degrees before intervention (Figure 4B Syn-3 with prominent weight at TA would be functioning in the late swing phase when the non-paretic side is considered healthy the smaller number of muscle synergies extracted on the non-paretic side contradicts with previous reports Changes were observed not only in the number of synergies but also in the weighting and activation of the muscles that make up the synergies both on the paretic and non-paretic sides although using 4 strides in the present study established the presence of changes in the EMG waveform of each stride whether it is appropriate to analyze less than 4 strides should be judged by the steadiness of the number of muscle synergies obtained from the results of NNMF analysis We used an analytical method different from previous reports, aiming to simplify the procedure and to allow on-site analysis. As shown in Figure 2 when four muscle synergies were detected on the non-paretic side and the paretic side we observed Syn-1 in early stance phase and at the next heel strike with strong involvement of the lower limb proximal muscles Syn-2 in late stance phase with involvement of the triceps surae Syn-3 in early swing phase with involvement of the tibialis anterior and Syn-4 in late swing phase with involvement of the hamstrings Since these four patterns of muscle synergies are consistent with those described in previous studies we consider that our analytical method is appropriate and valid The presence of fine fluctuations in the activity waveforms is probably because the low-pass filter that was a result of resampling was set at 40 Hz which differed from the conventional methods using low-pass filter set at 4 to 10 Hz (The results obtained in this study possibly depends on specific features of the methods used.) For NNMF analysis in this study, we averaged the data of four or eight strides and fed the averaged data into NNMF. We examined whether these results using averaged data differ from those using concatenated dataset, using the data of the fourth analysis (before discharge). We performed NNMF using concatenated datasets of all the 60 strides and of four strides each for the 60 strides (Supplementary Data) for both the paretic and non-paretic sides five synergies were extracted: synergy-1 to synergy-4 as obtained using averaged data with a fifth synergy that was often fragment of synergy-1 or -2 Even with the large concatenated dataset of 60 strides the results of concatenated data analysis are similar to those obtained from averaged data analysis it seems to be difficult to know precisely the roles of specific synergies in activities during a single gait cycle when using concatenated dataset We therefore used averaged data in NNMF analysis in this study Recordings of the paretic limb just before discharge showed that four muscle synergies were maintained in the majority (87%) of the gait observations The functional recovery of our patient was supported by synergy analysis To classify the extracted synergies by NNMF into the typical synergy types integrating the patterns of weights and activities is necessary because each synergy has specific roles in the gait cycle Stroke patients are known to have greater step length in individual steps and longer stride time in individual gait cycles compared with healthy individuals (Balasubramanian et al., 2009). However, the variability, expressed in standard deviation, for the weights and activities of muscles that constitute the muscle synergies in the paretic limb was smaller than that in the non-paretic limb (Figures 8A vs. C) There was also no difference in stride time between the paretic and the non-paretic sides This aspect must be examined in future studies The pattern of ankle joint angle during the gait cycle became similar to that of normal subjects Syn-3 with the prominent weight at TA would be functioning in the late swing phase compare the weights and EMG of these muscles) The cerebral cortex, basal ganglia, cerebellum, brainstem, and spinal cord are involved in gait (Takakusaki, 2017). The present case can be considered to have isolated corticospinal tract damage caused by the focal frontal lobe lesion. Bernstein (1967) proposed that in implementing complex movements in humans the brain does not control a large number of muscles individually but control groups of muscles (muscle synergies) to execute various repertoires of movements analyzing muscle synergies during the process of gait recovery in our patient will provide important clues for understanding the neural mechanisms involved in walking Assuming that muscle synergies composed of motor neurons controlling gait-associated muscles exist in the spinal cord We anticipate that the present study will provide some insights to answer the above questions In our previous report of this case, we presumed that the focal cerebral infarction in the left paracentral lobule was a complete infarct, destroying the motor cortex corresponding to the lower limb. Near-infrared spectroscopy (NIRS) measurement during treadmill gait showed an increase in oxyhemoglobin concentration near the right central sulcus, but no increase was observed near the left central sulcus corresponding to the lesion (Nagaoka et al., 2022) the cerebral cortex motor area is involved in voluntary contraction of individual muscles Based on the neurological symptoms of this case the motor cortex function of voluntary muscle contraction was impaired We explained these observations by hypothesizing that walking is controlled by structures other than the cerebral cortex motor area the increased blood flow near the right central sulcus may reflect a potential physiological response associated with gait (controlled by the non-paretic left lower limb) and over-activity of the unaffected (non-paretic) lower limb to compensate for the impaired balance caused by right lower limb paresis These data may reflect the changes in EMG pattern during walking as a result of compensation for the balance disturbance produced by the paretic lower limb exhibiting stereotype regardless of situation the variability of muscle activity increases and muscle synergies change on the unaffected (non-paretic) side which probably accounts for the increased standard deviations in activity level A limitation of this study is that we did not record biomechanical evidence to confirm the balance impairment caused by stereotype movements such as center of gravity sway on the paretic side the discussions regarding the difference in number of muscle synergies between the paretic and non-paretic sides remain hypothetical we cannot rule out the possibility that the characteristics of muscle synergies observed in this report reflect the use of a low-pass filter at a higher frequency of 40 Hz although many reports on gait of hemiplegic patients focus on the gait pattern and number of muscle synergies on the paretic side it is necessary also to consider the effect on the non-paretic side the optimal number of strides for analysis needs to be examined individually according to the purpose of the research and the magnitude of changes we explored the neuromechanical mechanisms underlying the gait recovery process of a monoplegic patient by conducting muscle synergy analysis combined with kinematics We investigated the new methodological approach for muscle synergy analysis elucidating various key factors for obtaining optimal results The findings have the potential to be used as indicators in gait training The utility of our methods in investigating the process of regaining gait function should be validated with more patients in the future The original contributions presented in this study are included in this article/Supplementary material further inquiries can be directed to the corresponding author The studies involving humans were approved by the Ethics Committee of Ishibashi General Hospital (2021-No The studies were conducted in accordance with the local legislation and institutional requirements The participants provided their written informed consent to participate in this study Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article The authors declare that no financial support was received for the research A part of the data in this manuscript was presented at the 60th Annual Meeting of the Japanese Association of Rehabilitation Medicine held on 29 June 2023 in Fukuoka We would like to thank Teresa Nakatani for translation of the Japanese manuscript The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fnhum.2023.1287675/full#supplementary-material The influence of merged muscle excitation modules on post-stroke hemiparetic walking performance Variability in spatiotemporal step characteristics and its relationship to walking performance post-stroke Shared muscle synergies in human walking and cycling The Coordination and Regulation of Movements Google Scholar Muscle synergy patterns as physiological markers of motor cortical damage How to decide the number of gait cycles in different low-pass filters to extract motor modules by non-negative matrix factorization during walking in chronic post-stroke patients Merging of healthy motor modules predicts reduced locomotor performance and muscle coordination complexity post-stroke The association between motor modules and movement primitives of gait: A muscle and kinematic synergy study Changes in synergy associated with changes in motor function in post-stroke hemiplegic patients: Longitudinal study of synergy extracted by non-negative matrix factorization (NNMF) Merging and fractionation of muscle synergy indicate the recovery process in patients with hemiplegia: The first study of patients after subacute stroke Gait training after stroke with a wearable robotic device: A case report of further improvements in walking ability after a recovery plateau Comparison of motor control deficits during treadmill and overground walking poststroke Can gait analysis improve gait training in stroke patients Google Scholar Different types of disturbed motor control in gait of hemiparetic patients Effect of physical therapy on muscle synergy structure during standing-up motion of hemiplegic patients Google Scholar In terms of neurophysiology: Simplifying redundant degree of freedom in human musculoskeletal system based on muscle synergies Google Scholar Learning the parts of objects by non-negative matrix factorization PubMed Abstract | Crossref Full Text | Google Scholar Association between temporal asymmetry and muscle synergy during walking with rhythmic auditory cueing in survivors of stroke living with impairments Specifications of an electromyogram-driven neuromuscular stimulator for upper limb functional recovery Role of primary motor cortex in gait: Automatic-voluntary dissociation seen in paretic leg of a patient who had a stroke Computer-assisted gait training (CAGT) of hemiparetic stroke patients: Whose recovery is most predictable Reduction of common motoneuronal drive on the affected side during walking in hemiplegic stroke patients Motor modules of human locomotion: Influence of EMG averaging The influence of locomotor rehabilitation on module quality and post-stroke hemiparetic walking performance Simultaneous recording system for digital video pictures and electric signals Google Scholar Electromyographic analysis with reference to the role of the globus pallidus Relationship between stride length and walking rate in gait training for hemiparetic stroke patients Functional neuroanatomy for posture and gait control PubMed Abstract | Crossref Full Text | Google Scholar Differences in muscle synergy symmetry between subacute post-stroke patients with bioelectrically-controlled exoskeleton gait training and conventional gait training A limited set of muscle synergies for force control during a postural task Functional Differentiation of Human Skeletal Muscle Corticalization and Spinalization of Movement Google Scholar Clarify sit-to-stand muscle synergy and tension changes in subacute stroke rehabilitation by musculoskeletal modeling Temporal features of muscle synergies in sit-to-stand motion reflect the motor impairment of post-stroke patients Google Scholar Kumakura Y and Nagaoka M (2024) Analysis of muscle synergy and gait kinematics during regain of gait function through rehabilitation in a monoplegic patient Copyright © 2024 Ebihara, Hirota, Kumakura and Nagaoka. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) distribution or reproduction in other forums is permitted provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited in accordance with accepted academic practice distribution or reproduction is permitted which does not comply with these terms *Correspondence: Masanori Nagaoka, bmFnYW9rYW1AanVudGVuZG8uYWMuanA= Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher 94% of researchers rate our articles as excellent or goodLearn more about the work of our research integrity team to safeguard the quality of each article we publish Nagaoka University of Technology (NUT) held the 9th International Conference on "Science of Technology Innovation" 2024 (9th STI-Gigaku 2024) STI-Gigaku is an international conference mainly organized by our students with the purpose of promoting efforts to achieve the Sustainable Development Goals (SDGs) The conference is dedicated to bringing together all its respective parties?NUT KOSEN (National Institute of Technology/College of Technology) and companies/research institutes?to provide opportunities to facilitate the discussion of issues and solutions on global topics by sharing progress and achievements in education and research collaboration The 9th STI-Gigaku 2024 was held in Aore Nagaoka as the main venue and at the NUT almost 390 people from universities in Japan and overseas and other organizations attended the event and adding momentum to efforts to achieve the SDGs activities leading to solutions for the SDGs and results of joint research between KOSEN and NUT were presented in English specifying the target SDGs and lively discussions and exchanges were made the event provided opportunities for KOSEN students to experience the atmosphere of research presentations at an international conference Ten outstanding presentations were awarded the "Best Research Presentation Award by Sumitomo Riko Company Limited," and 11 presentations received the "Best Research Presentation Award." This year was the first time in four years that this conference was held only on-site it was a great success owing to the efforts of the companies that sponsored or supported the event and all of those who participated or lent their support on the day We would like to thank you for your kind support We will continue to hold the International Conference and will work together across disciplinary boundaries to promote efforts to achieve the SDGs with various related organizations Over view of the program, award winnershttps://www.nagaokaut.ac.jp/annai/daigakusyokai/sdgs/STI-Gigaku/9thstigigaku2024.html Copyright© Nagaoka University of Technology. All Rights Reserved. Volume 5 - 2018 | https://doi.org/10.3389/frobt.2018.00115 This paper presents detumbling and capture of space debris by a dual-arm space robot for active space debris removal missions such as a malfunctioning satellite or a rocket upper stage It also has uncertainties in its parameters such as inertial characteristics or surface frictional roughness These factors make the debris capture missions difficult to accomplish we propose a detumbling and capture control method for a dual-arm robot based on repeated impact capable of suppressing the debris motion by repeatedly utilizing an effect of a passive damping factor in the contact characteristics as the initial step of a study on the repeated impact-based capture method we assume that the capture target is a rocket upper stage that can be simply modeled as a cylindrical body and mainly has angular velocity motion in its principle axis of inertia A motion tracking control law of an end-effector of the robot arm is introduced to maintain the repeated impact The proposed control method enables the robot to accomplish the detumbling and capture without precise estimation of the inertial characteristics and surface frictional roughness of the debris The validity of the proposed method is presented by numerical simulations and planar microgravity experiments using an air-floating system the experimental evaluation shows the fundamental feasibility of the proposed method the result contributes to a practical application This method basically assumes the condition that the target parameters On the other hand, the detumbling and capture of space debris by a dual-arm robot system has been proposed. Figure 1 illustrates a typical capture sequence of space debris by a dual-arm space robot The capture sequence is divided into three phases of approaching The capture strategy by a dual-arm robot can potentially allow unexpected pushing-away of the debris by impounding of the dual arm unlike a single-arm robot the dual-arm robot can enclose the target motion with uncertainties by dual arms whereas the single-arm robot is risk for unexpected pushing-away or collision of uncertain debris without accurate parameter estimation This study focuses on the robot manipulation in the detumbling and capturing phases after the approaching phase Capture sequence of space debris by a dual-arm space robot Its dual arm contacts the same plane of the uncooperative target These past works assume that mass and moment of inertia of the target are fully known detumbling and capture of uncertain tumbling debris by a sequential or continuous control framework is a challenging technology detumbling and capture technologies associated with experimental validation have been limited we propose a repeated impact-based detumbling and capture method by a dual-arm space robot The tumbling or spinning motion decays by a repeated damping effect of the repeated impact the robot can maintain the repeated impact by which the direction of the target's linear velocity is constrained by controlling each contact point the relative translational velocity between the robot base and target is zero and each impact imparts a small relative velocity this is limited by a proper choice of the subsequent impact points Therefore it enables the detumbling and capture of space debris without precise control of contact force depending on target's inertial parameters The validity of the proposed method is also evaluated by both numerical simulation and a ground experiment that emulates planar microgravity Section 2 introduces definition of the capture target and modeling of the dual-arm space robot with contact dynamics Section 3 presents a repeated impact-based control law for detumbling the target spin The control method includes motion tracking control to achieve the repeated impact Section 4 shows simulation analysis of the proposed control method Section 5 shows experimental validation of the proposed control method A planar microgravity experiment is performed by using an air floating system The experimental result confirm the fundamental effectiveness and feasibility of the proposed method section 6 summarizes the contributions of this paper Definition of the capture target and fundamental modeling of the dual-arm space robot and target are presented in this section In this paper, to primarily demonstrate an effectiveness of an idea of the repeated impact-based capture, we assume that the capture target is a rocket upper stage as an initial step. The upper stage is one of the space debris to be removed (Williams and Meadows, 1978; Shan et al., 2016; Bylard et al., 2017) Most of the upper stages can be approximately modeled as a cylindrical body and some of them are also deemed to be a stable floating state with a single spin in its principle axis of inertia because of its mass distribution and gravity from the earth's gravitational attraction this paper focuses on the capture of a cylindrical free-floating object which can be approximately defined as a planar motion Figure 2 illustrates a planar model of a dual-arm robot (chaser robot) and target debris where ΣI is an inertial coordinate system • The influence of gravity acceleration can be ignored because of microgravity in orbit • Planar motion is targeted for simplicity • The chaser robot is comprised of main base and serial link arms (dual-arm) • Contact occurs between the arm's end-effector (spherical tip) and target surface • The target is a circular object in two dimensions and its center of mass coincides with its geometric center • Radius and center of mass position of the target are known and frictional property of the target are unknown and contact force and torque are generated at only the contact point • Contact surface of the target is smooth and uniform Target capture model by a dual-arm space robot the radius and center of mass position of the target can also be assumed to be estimated based on an on-orbit measurement of the target's spinning motion In this paper, the dual-arm is defined as left and right arms. A superscript k, which is 1 or 2, is shown to discern each arm. The link number of each arm is kn and the whole joint number n is n =1n+2n. The variables are defined in ΣI, unless otherwise noted. Based on the Lagrange's equation, the equation of motion of the dual-arm space robot is introduced as follows (Umetani and Yoshida, 1993): • k̄: the other value of k (1 or 2) k̄=2 when k = 1 and k̄=1 when k = 2 cb∈ℝ6: inertia matrix and non-linear velocity-dependent term of the robot base attitude kcm∈ℝkn: inertia matrix and non-linear velocity-dependent term of the robot arm k • kHbm∈ℝ6×kn: interference matrix between the robot base and robot arm k • xb∈ℝ6: position and attitude of the robot base • k ϕ∈ℝkn: joint angle of the arm k • k τ∈ℝkn: joint torque of the arm k kFh∈ℝ6: external force and moment on the robot base and the end-effector of the arm k • kJb∈ℝ6×kn: Jacobian matrix with respect to the robot base and the robot arm k • kJm∈ℝ6×kn: Jacobian matrix with respect to the robot arm k the equation of motion of the arm k in the joint space is derived as The contact force and torque are generated at the contact point where these are nominally defined as the force and torque acting on the target the force and torque in an inverse direction reacts on the end-effector of the chaser the contact force and torque acting on the target contact surface are converted into the force and torque acting on the center of mass position of the target Given that the contact force FP exerts at a point P on the target surface the converted force FA and torque TA acting on A are given as rAP is the position vector of the contact point P from A xP′ and yP′ are parallel to xp and yp The unit vector of xP′ and yP′ are also eP′x and eP′y Contact force model of a spherical end-effector and a rigid target The contact force normal to the contact surface is defined as a linear spring-damper model as where Kn and Cn are the contact stiffness and damping coefficients in a normal direction to the contact surface In the tangential direction to the contact surface we assume that kinetic friction is exerted during contact The friction force is simply modeled as Coulomb friction a kinetic frictional coefficient and relative tangential velocity on the contact surface the tangential contact force can be given as the direction of the contact force is determined by θP regardless of the target attitude because the target is circular in shape This section elaborates on the control law in accordance with the models defined in the previous section We propose a repeated impact-based control method for detumbling and capture of a spinning object by a dual-arm space robot in orbit the dual-arm robot must control its dual arm to avoid escape of the target from its work-space a tracking control law for the dual arm to adapt the post-impact target motion is first introduced a capture sequence of the target based on the repeated impact-based control is presented Although the modeling in the previous sections is defined as three-dimensional as a generalized form the following control law focuses simply on two-dimensional motion During the motion tracking control of one arm and the attitude of the robot base is not controlled Path tracking control model for chaser arm Set the contact angle θp and tracking angle θh which is predicted by the position and velocity of the center of mass and the contact angle θp of the target Calculate the confluence point Q of the arm and the target based on the arm's end-effector position Calculate the norm of the end-effector velocity so that it can reach Q earlier than the target Calculate the desired end-effector velocity dvh by using θh and the norm of the end-effector velocity pt=[xtyt]T and vt=[ẋtẏt]T are position and velocity of the center of mass of the target in ΣI and the radius of the circular target is defined as rt The position and velocity of the end-effector are also ph=[xhyh]T,vh=[ẋhẏh]T the angle of the contact point from the target center of mass and the angle between the predicted path and the desired end-effector's velocity be Q=[xQyQ]T the predicted motion path lt is defined as y = atx + bt where ẋt ≠ 0 and ẏt ≠ 0 given that the desired path of the arm is lh : y = ahx + bh the following relationship must be satisfied: the arm needs to reach Q earlier than the target the norm of the desired velocity of the end-effector which is determined so that the arm can reach Q earlier than the target kh ≥ 1 is given for the tracking control Given the inclination angle of the desired path as ah = ẏh/ẋh the desired velocity of the end-effector is derived as The end-effector velocity is determined based on the relative position of the end-effector and the target center of mass the end-effector's desired velocity dvh can be given as the desired joint velocity of the arm is introduced The angular velocity of the end-effector while the arm is tracking the target is controlled to be zero so that the attitude of the end-effector is kept in the tracking mode where, J+ is the pseudo-inverse matrix of the generalized Jacobian matrix (Umetani and Yoshida, 1993) To maintain the repeated impact, selection of the contact point on the target surface is a key parameter. For instance, assuming the desired contact points on a frictional object, xp and x̄p, are independently defined as θp and θ̄p, as shown in Figure 5 the direction of the target motion and desired contact point are changed by each impact because the resultant contact force FP is not oriented to the target center of mass the arm is at risk of not tracking the target motion the control constraint θp=θ̄p is given so that the angle of the contact point becomes constant for the case where μ = |Ft|/|Fn| is given as a constant value the direction of the contact force is also constant even if the force amplitude varies the constraint θp=θ̄p allows the restraint of the target motion in a single-axial direction in ΣI Schematic of relationship between contact force and contact point Let the directional angle of the velocity of the end-effector to the target's motion path lt be θh Given 0 ≤ θh ≤ π/2 the dual-arm is controlled to simultaneously track the given path and close the gap distance between the end-effectors the symmetric control parameter θh=θ̄h is applied as a typical case The final state of the motion tracking control corresponds to the capture completion of the target by the dual arm This shows that detumbling and capture can be achieved by the common control framework When θh=θ̄h is satisfied the contact points and the target center of mass are located along a straight line because each arm targets its desired contact point as xp or x̄p by which the velocity of both end-effectors is controlled to be zero at the final state where they simultaneously contact the target Figure 6 shows a schematic view of the repeated impact-based capture sequence of the free-floating target by the dual-arm space robot The sequence is summarized in the following four steps where it is assumed that the post-approaching state after the dual-arm robot is controlled to approach the target so that the relative linear velocity becomes zero The dual-arm is controlled to approach the target with a constant velocity kvh(=k̄vh) until one of the dual-arm shoves the target away the other arm ahead of the target motion is controlled by the path tracking control with dvh to the target velocity vt before the impact the other arm maintains a stationary state the linear and angular velocity of the target obviously decay The robot repeats sequences 2 and 3 until both arms contact the target simultaneously (i.e. Capture sequence based on repeated impact by a dual-arm space robot The proposed method enables the detumbling and capture of the target by a single control law this method can be applied to the capture of uncertain debris because the precise values of the target's inertial properties and surface physics are explicitly not included Although the control method targets the planar motion to discuss its fundamental effectiveness and feasibility for starters its basic concept can be expanded to a three-dimensional situation this section presents a two-dimensional simulation analysis The numerical simulation shows the validity and effectiveness of the proposed method the spring stiffness is designed to be much lower than the contact stiffness of a rigid body collision Employing this configuration enables the approximation of the contact parameters as known mechanical properties of the spring of Kn = 900 [N/m] and Cn = 6 [N·s/m] in the contact force model of the rigid body collision Such a compliant component also works passively as an adaptive factor to errors of sensing the relative position/motion and controlling the end-effector μ = 0.1 is set as an unknown parameter for the chaser Simulation model of chaser robot and target (left: schematic view The initial angular velocity of the target is ωt0 and the initial approaching velocities of the arm are 1vh and 2vh both the initial linear velocity of the relative motion and the initial angular velocity of the chaser are set to zero the end-effectors are initially located on a straight line that passes through the target center of mass we set 1 ϕ = [60° −90°− 60°]T 2 ϕ = [−60° 90° 60°]T θh=40°(<90°) and kh = 10 are used as the control parameters Figures 8–10 show the simulation results. Figure 8 shows snapshots of the chaser and target, and Figures 9, 10 depict the time histories of the variables The plotted variables are represented in the inertial coordinate system except for the desired contact position and the distance between the end-effectors Time histories of simulation variables in simulation Although the capture performance is intricately linked with various parameters of both the robot and target it is concluded that the effectiveness of the capture of an uncertain target based on the proposed control method is numerically verified this section presents the experimental evaluation to verify the fundamental feasibility of the proposed control method Figure 11 shows an overview of the experimental setup Air floating test beds that can emulate planar motion in microgravity on a flat stone plane were used for simulating the chaser robot and target the position and attitude of the chaser base and target were precisely measured by an external motion tracking camera system (OptiTrack FLEX:V100R2; NaturalPoint Inc.) whose sampling frequency is 100 Hz The tracking data was transmitted to the chaser as feedback information without any cables the chaser was able to calculate the position and linear velocity of the target center of mass as well as the attitude angle and angular velocity around it In the experiment, two air floating test beds were used as the dual-arm chaser robot and the cylindrical target. These test beds were equipped with air-tanks and air-bearings (S102501 and S104001; NEWWAY Air Bearings) on their bottom surface. Pressure-controlled air-injection from the air-bearings enabled the test beds to perform frictionless motion for several minutes. Figure 12 shows an overview of the air floating robot where an aluminum spherical tip and a spring as mechanical compliance are attached on each arm The air floating target quips an acrylic pipe with plastic tapes on its surface to emulate a circular object in two dimensions Air floating test beds for planar microgravity experiment (left: overview of a chaser test bed of a dual-arm robot micro-controllers (SH7125 and SH7144; Renesas Electronics Corp.) and motor drivers (1XH Power Module; HiBot Corp.) for driving the dual-arm are installed Lithium-ion batteries (E-HL9S; IDX Company Ltd.)are mounted on the robot base as the power source The chaser robot can control its motion based on the on-board computer the real-time data of the position and attitude of the robot base and target obtained by the motion tracking cameras can be sent to the on-board computer via wireless communication The arm comprises three DC brushed motors (RH-8D-3006-E100AL; Harmonic Drive Systems the linear velocity of the chaser and target was set to zero and only the target angular velocity was given we also set 1 ϕ = [60° −40° −110°]T 2 ϕ = [−60° 40° 110°]T The control parameters were selected with the same values as in the previous simulation the initial center of mass position of the target was also located between the end-effectors with an offset distance Figures 13, 14 show the experimental results. Figure 13 shows snapshots of the top view of the experiment. Figure 14 depicts the time histories of the sensor data Snapshots of experimental result (top view) Time histories of state variables in experiment (A) Joint angle of arm 1 (left-side in top view) (B) Joint angle of arm 2 (right-side in top view) First, the results confirmed that the repeated impulse-based capture was experimentally demonstrated. From Figures 14A,B the time histories of the joint angles show the change of the motion tracking control Although the change of the target linear velocity was relatively small because of a small damping coefficient of the spring the target angular velocity was damped at each impact the target angular velocity was suppressed by the frictional effect It is also confirmed that the motion of the chaser and target converged to a steady state with a small constant velocity in the final capture state the results conclude that fundamental feasibility of the capture of an uncertain target based on the proposed control method is experimentally demonstrated To apply the proposed capture method to more complicated debris like a malfunctioning satellite with tumbling motion in three-dimension effects of the debris' shape and surface roughness and tumbling motion will need to be considered to cope with such a challenging capture mission the tracking control law must be improved in addition to higher DOF of the arm The current tracking control assumes that the debris' shape is axially symmetric and thereby there is little constraint on the contact timing and the arm motion so far as the end-effector reaches a confluence point faster than the target which proper momentum exchange is repeatedly accomplished a possible future work for advanced applications This paper presented a repeated impact-based capture control for a dual-arm space robot and its experimental validation As the initial study of the repeated impact-based capture the capture target was assumed to be a rocket upper stage that can be modeled as a single spinning cylinder The proposed control method can achieve detumbling and capture of spinning space debris having uncertainties in its mass and moment of inertia The validity of the control method was also demonstrated based on the numerical and experimental analyses a key contribution of this paper is the verification of the fundamental feasibility of the control method through an experimental evaluation on the ground while the target is simply assumed to be a cylindrical object the results of this study are expected to contribute to a real space robot system an implementation of on-board sensing capable of measuring the relative position and velocity in addition to a robustness analysis of the developed control method to the initial conditions and control parameters the method needs to be expanded to three-dimensional capture and a more complicated target shape and surface roughness like a malfunctioning satellite KN and RK developed the theoretical framework and performed the experimental verification All authors discussed the results and contributed to the final manuscript “Robust capture and deorbit of rocket body debris using controllable dry adhesion,” in Proceedings: 2017 IEEE Aerospace Conference (Big Sky Google Scholar “Validation of a net active debris removal simulator within parabolic flight experiment,” in Proceeding: 12th International Symposium on Artificial Intelligence Robotics and Automation in Space (iSAIRAS) (Montreal Google Scholar Literature survey of contact dynamics modeling CrossRef Full Text | Google Scholar Eddy currents applied to de-tumbling of space debris: analysis and validation of approximate proposed methods CrossRef Full Text | Google Scholar Dynamic capturing strategy for a 2-D stick-shaped object based on friction independent collision CrossRef Full Text | Google Scholar Feasibility of noncontacting electromagnetic despinning of a satellite by inducing eddy currents in its skin – part I: analytical considerations Google Scholar Angular momentum reduction using mechanical impulse for uncontrollable satellite capturing CrossRef Full Text | Google Scholar Rotational motion-damper for the capture of an uncontrolled floating satellite CrossRef Full Text | Google Scholar PubMed Abstract | Google Scholar “Impedance control for free-flying space robots – basic equations and applications,” in Proceeding Intelligent Robots and Systems 2006 IEEE/RSJ International Conference (Beijing: IEEE) Google Scholar Review and comparison of active space debris capturing and removal methods CrossRef Full Text | Google Scholar A combined impedance-PD approach for controlling a dual-arm space manipulator in the capture of a non-cooperative target CrossRef Full Text | Google Scholar “Detumbling an uncontrolled satellite with contactless force by using an eddy current brake,” in Proceeding 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems (Tokyo: IEEE) Google Scholar “Hybrid simulation of a dual-arm space robot colliding with a floating object,” in Proceeding 2008 IEEE International Conference on Robotics and Automation (Pasadena Google Scholar “Control of space manipulators with generalized Jacobian matrix,” in Space Robotics: Dynamics and Control Kanade (Dordrecht: Kluwer Academic Publishers) Google Scholar “Impedance-based contact control of a free-flying space robot with a compliant wrist for non-cooperative satellite capture,” in Proceeding 2012 IEEE/RSJ International Conference Intelligent Robots and Systems (Algarve: IEEE) Google Scholar and the spin decay of cylindrical rocket bodies in orbit Planet CrossRef Full Text | Google Scholar “ Throw-nets and tethers for robust space debris capture,” in Proceeding 64th International Astronautical Congress (Beijing: IAF) Google Scholar Impulsive control for angular momentum management of tumbling spacecraft CrossRef Full Text | Google Scholar Kameoka R and Yoshida K (2018) Repeated Impact-Based Capture of a Spinning Object by a Dual-Arm Space Robot Received: 12 December 2017; Accepted: 13 September 2018; Published: 16 October 2018 Copyright © 2018 Nagaoka, Kameoka and Yoshida. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) *Correspondence: Kenji Nagaoka, bmFnYW9rYUBhc3Ryby5tZWNoLnRvaG9rdS5hYy5qcA== Today's print edition Home Delivery The industry ministry held a briefing session in Niigata Prefecture on Sunday to seek understanding from local people for the envisaged restart of reactors at the Kashiwazaki-Kariwa nuclear power plant It was part of meetings that the government plans to hold in all municipalities in the prefecture except the city of Kashiwazaki and the village of Kariwa with an aim of winning local understanding for the reactor restart.googletag.cmd.push(function() { googletag.display('div-gpt-ad-1499653692894-0'); }); The first session was held on Tuesday last week The remaining sessions will take place in stages during the period until early February 2025 the prefecture has a total of 30 municipalities About 60 local people took part in Sunday's meeting in Nagaoka Many areas in Nagaoka are within 30 kilometers of the Tokyo Electric Power Company Holdings nuclear plant Officials from the ministry explained plans to allow the restart of reactors whose safety has been confirmed in light of the needs to ensure stable electricity supply and promote decarbonization one local resident said: "We were unable to evacuate when a major earthquake struck in the past because roads were cut off How can you evacuate some 100,000 people in the event of a complex disaster?" "Why do we have to sacrifice ourselves to send electricity to Tokyo?" "We will put safety first," a ministry official said "We are ready to firmly deal with your anxiety." In a time of both misinformation and too much information quality journalism is more crucial than ever.By subscribing Your subscription plan doesn't allow commenting. To learn more see our FAQ Sponsored contents planned and edited by JT Media Enterprise Division Metrics details We load the plaquette with three electrons and demonstrate the predicted emergence of spontaneous ferromagnetic correlations through pairwise measurements of spin We find that the ferromagnetic ground state is remarkably robust to engineered disorder in the on-site potentials and we can induce a transition to the low-spin state by changing the plaquette topology to an open chain This demonstration of Nagaoka ferromagnetism highlights that quantum simulators can be used to study physical phenomena that have not yet been observed in any experimental system The work also constitutes an important step towards large-scale quantum dot simulators of correlated electron systems The datasets obtained from the measurements described in this work are available in the repository Zenodo with the identifier https://doi.org/10.5281/zenodo.3258940 The code used to plot the datasets and implement the models used to reproduce all the figures in the main manuscript is available in the repository Zenodo with the identifier https://doi.org/10.5281/zenodo.3258940 The Theory of Magnetism Made Simple (World Scientific A 2 × 2 quantum dot array with controllable inter-dot tunnel couplings Eigenvalues and magnetism of electrons on an artificial molecule Nanoscale ferromagnetism in nonmagnetic doped semiconductors Kondo screening of a high-spin Nagaoka state in a triangular quantum dot Probing interaction-induced ferromagnetism in optical superlattices Time-resolved observation and control of superexchange interactions with ultracold atoms in optical lattices Experimental realization of plaquette resonating valence-bond states with ultracold atoms in optical superlattices Quantum simulations with ultracold quantum gases Four-body ring-exchange interactions and anyonic statistics within a minimal toric-code Hamiltonian Enhancement and sign change of magnetic correlations in a driven quantum many-body system Direct observation of incommensurate magnetism in Hubbard chains Spin transport in a Mott insulator of ultracold fermions Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice Quantum simulation of the Hubbard model with dopant atoms in silicon Digital quantum simulation of fermionic models with a superconducting circuit Real-time dynamics of lattice gauge theories with a few-qubit quantum computer Electron transport through double quantum dots A quantum-dot array as model for copper-oxide superconductors: a dedicated quantum simulator for the many-fermion problem Quantum simulation of Fermi-Hubbard models in semiconductor quantum-dot arrays Quantum dot systems: a versatile platform for quantum simulations Quantum simulation of a Fermi–Hubbard model using a semiconductor quantum dot array A few-electron quadruple quantum dot in a closed loop Charge frustration in a triangular triple quantum dot A triangular triple quantum dot with tunable tunnel couplings Mortemousque, P.-A. et al. Coherent control of individual electron spins in a two dimensional array of quantum dots. Preprint at http://arxiv.org/abs/1808.06180v1 (2018) The case for \({d}_{{x}^{2}-{y}^{2}}\) pairing in the cuprate superconductors Pairing symmetry in cuprate superconductors From Nagaoka’s ferromagnetism to flat-band ferromagnetism and beyond: An introduction to ferromagnetism in the Hubbard model Electron correlations in narrow energy bands Theory of ferromagnetism and the ordering of electronic energy levels Ab initio exact diagonalization simulation of the Nagaoka transition in quantum dots Semiconductor quantum dots for electron spin qubits Electron spin decoherence in quantum dots due to interaction with nuclei Electron spin relaxation by nuclei in semiconductor quantum dots Nuclear spin effects in semiconductor quantum dots Coherent manipulation of coupled electron spins in semiconductor quantum dots Control and detection of singlet-triplet mixing in a random nuclear field Significance of electromagnetic potentials in the quantum theory Coherent control of a single electron spin with electric fields Spin of a multielectron quantum dot and its interaction with a neighboring electron Download references We acknowledge input and discussions with M thanks the NSF-funded MIT-Harvard Center for Ultracold Atoms for its hospitality This work was supported by grants from the Netherlands Organisation for Scientific Research (FOM projectruimte and NWO Vici) (J.P.D. the European Research Council (ERC-Synergy) (V.P.M. the Postdoctoral Fellowship in Quantum Science of the Harvard-MPQ Center for Quantum Optics and AFOSR-MURI Quantum Phases of Matter (grant number FA9550-14-1-0035) (Y.W.) the Swiss National Science Foundation (C.R. Present address: School of Mathematical and Physical Sciences had equal contribution in conceptualization Experimental investigation and methodology was performed with equal contribution from J.P.D Theoretical investigation was led by J.P.D. had equal contribution in the formal analysis led the funding acquisition and supervision led the resources (device fabrication) with support from J.P.D led the resources (heterostructure growth) Please refer to the Casrai Credit Taxonomy for definitions of each of these roles The authors declare no competing interests Peer review information Nature thanks Joe Salfi reviewer(s) for their contribution to the peer review of this work a, Measured charge stability diagram showing both point N and point M, as highlighted in Fig. 2a Measured charge stability diagram focusing on the 2001:1101 charge transition where spin measurements are performed (point M) Sample charge stability diagram where we have highlighted the visible interdot transitions where the electrochemical potentials of two dots become resonant (that is an electron is allowed to tunnel between the two dots) where we have modified gates P1 and P3 such that the interdot transitions appear at different locations in the diagram Dashed black lines delimit the regions with a fixed total electron occupation in the system gates P1 and P3 have been tuned to observe the Nagaoka condition where the three visible interdot transitions are aligned in the three-electron configuration The intersite interaction in the system provides an effective isolation from the reservoirs for a narrow range of gate voltages such that the system can remain stable with three electrons in the resonant configuration a, Average PT in the detuning region 1.00 < pε < 1.01 for 40 values of τramp within the same range shown in Fig. 3. Solid lines are fits using the time evolution simulations described in the Supplementary Methods for different values of distance \(\ell \) between neighbouring dots Inset shows the unscaled results of the time-evolution simulations where the probability of s = 3/2 is the sum of the lowest four eigenstate probabilities from the final evolved state PT is measured for increasing wait times at point N for diabatic (blue) and adiabatic (red) passages Solid lines are exponential fits as guide to the eye Schematic of the methodology used in the ab initio simulations to reproduce the effect of the four-dot system transition from a 2D plaquette to a 1D chain which effectively varies the distance between two of the dots The ground-state energy and spin configuration (b) and the ferromagnetic to low-spin energy gap ΔE as a function of θ (c) The ground state soon becomes a low-spin state for the rotating angle at 0.3° Schematic of the methodology used in the ab initio simulations to reproduce the effect of a local energy offset The amplitude of the potential V of one of the quantum wells is changed by an amount dV The variation of the single-well potential by positive or negative dV gives unbalanced site energies the hybridization and interaction parameters are also affected in the ab initio calculation The ground-state energy and spin configuration (b) and the ferromagnetic to low-spin energy gap ΔE as a function of dV (c) When the potential detuning is dV = 0.11 meV or dV = −0.07 meV the system undergoes a transition to a low-spin ground state The transitions at these two directions have a different nature the particular quantum dot is deeper and tends to trap more electrons a negative dV raises the energy cost on the particular quantum well and leads to a lower probability of occupation in a three-electron system Without the ‘mobile’ hole in the ‘half-filled’ system the ground state becomes a low-spin state instead of a Nagaoka ferromagnetic state Same measurement as in Fig. 6 applying the ±50 μeV offset on each of the four dots Panels correspond to offsets in dots 1 to 4 Note that the asymmetry in the plots is related to the fact that the local energies at point M are in an asymmetric detuning configuration and we pulse linearly from this configuration to point N the simulated energies of the different spin states at point N (pε = 1) Each pair of panels show experimental measurements (left) and simulated spectra (right), where point N has been redefined such that the chemical potential of dot 1 is offset by the amount shown on the top right of each panel. Green crosses highlight the detuning points used to obtain the values in Fig. 6b these points where obtained using a peak-finding algorithm (local maxima by simple comparison with neighbouring values); for simulated plots the points correspond to the energy-level crossings This file contains Extended Fermi-Hubbard models used to simulate different experiments in the main text Ab initio exact diagonalisation simulations of the 2×2 plaquette and Mapping 3-spin states onto 2-spin measurements Download citation DOI: https://doi.org/10.1038/s41586-020-2051-0 A former village in central Japan that was hit by a powerful earthquake 20 years ago is continuing to stage traditional bullfights as a symbol of the region's reconstruction "I hope this community will survive by continuing the bullfights," said Tomie Matsui head of the Yamakoshi bullfighting association which organizes the ushi no tsunotsuki event in the Yamakoshi district of Nagaoka Niigata Prefecture.googletag.cmd.push(function() { googletag.display('div-gpt-ad-1499653692894-0'); }); was devastated by the quake that struck the Chuetsu central region of the prefecture on Oct killing 68 people and injuring 4,805 others Metrics details The dynamical response of a quantum spin liquid upon injecting a hole is a pertinent open question measured momentum-resolved in angle-resolved photoemission spectroscopy (ARPES) or locally in scanning tunneling microscopy (STM) can be used to identify spin liquid materials we employ tensor network methods to simulate the time evolution of a single hole doped into the Kitaev spin-liquid ground state we reveal two fundamentally different scenarios the spin liquid is highly susceptible to hole doping: a Nagaoka ferromagnet forms dynamically around the doped hole in the case of antiferromagnetic spin couplings the hole spectrum demonstrates an intricate interplay between charge best described by a parton mean-field ansatz of fractionalized holons and spinons we find a good agreement of our numerical results to the analytically solvable case of slow holes Our results demonstrate that dynamical hole spectral functions provide rich information on the structure of fractionalized quantum spin liquids including possible topological superconductivity dynamical Nagaoka ferromagnetism from quenching a ground state with a hole has remained unexplored When inserting a single hole into the Kitaev spin liquid the hole either dynamically reorders the spin background into a Nagaoka ferromagnet for ferromagnetic (FM) spin couplings J > 0 or fractionalizes into spinon and holon quasiparticles for antiferromagnetic (AFM) spin couplings J < 0 The exactly solvable Kitaev model8 is a paradigmatic example of a quantum spin liquid hosting topological order and fractionalized excitations we summarize some of its most important properties where the first, second, and third terms act on x-, y-, and z-bonds of a honeycomb lattice, respectively, see Fig. 1 Throughout this work we will fix ∣Jx∣ = ∣Jy∣ ≡ ∣J∣ = 1 The system undergoes a phase transition from a gapped \({{\mathbb{Z}}}_{2}\) topological phase for ∣Jz∣ > 2 to a gapless phase for ∣Jz∣ < 2 these phases exist for both signs of the Kitaev couplings J we will examine both ferromagnetic couplings J > 0 and antiferromagnetic couplings J < 0 and focus on the gapped case We find qualitatively similar behavior for the gapless phase; see “Methods” section for additional data The Kitaev model hosts an extensive number of conserved quantities, described by the flux operator around a plaquette; see inset in Fig. 2c: For each plaquette W has eigenvalues ±1. The ground state is in the flux free sector, where 〈W〉 = +1 for all plaquettes. Accordingly, we say that a flux is introduced into the system if 〈W〉 = −1 for one of the plaquettes. a Typical examples for snapshots of the Fock configurations occurring with large probability in the wave function; see Eq. (6); obtained from matrix product states (MPS) at times τ = 0 [1/J] and τ = 10 [1/J] are shown We identify the FM cluster size NC by connecting all spins pointing up (purple dots) or down (orange dots) starting from the hole site (green dots) b Extracted from 10,000 snapshots of the state at each time a large ferromagnetic (FM) cluster of spins forms around the hole the cluster has a size of Nc ≈ 35 (40) sites for hopping constants t/J = 3 (6) The speed of the FM cluster expansions is set by the hopping constant t; see dashed lines fitted to the snapshot data the flux operator average 〈W〉 decays with time All data shown is for ferromagnetic couplings J > 0 and anisotropy Jz/J = 2.5 For the exact solution of Eq. (1) the spin operators are decomposed into matter Majorana fermions \({\chi }_{i}^{0}\) and bond Majorana fermions \({\chi }_{i}^{a}\) [a ∈ (x such that \(\{{\chi }_{i}^{\alpha },{\chi }_{j}^{{\alpha }^{{\prime} }}\}=2{\delta }_{ij}{\delta }_{\alpha {\alpha }^{{\prime} }}\) [α ∈ (0 the spins are written in terms of the Majorana fermions as Introducing directed bond operators \({\hat{u}}_{{\langle ij\rangle }_{a}}=i{\chi }_{i}^{a}{\chi }_{j}^{a}\) from the A to the B sublattice The gauge operators \({\hat{u}}_{{\langle ij\rangle }_{a}}\) commute with each other and with the matter Majorana fermions the Hamiltonian splits into separate sectors of the bond operators which have eigenvalues \({u}_{{\langle ij\rangle }_{a}}=\pm 1\) the plaquette operator W can be expressed as a product of \({\hat{u}}_{{\langle ij\rangle }_{a}}\) around a hexagon as \(W={\hat{u}}_{{\langle 12\rangle }_{x}}{\hat{u}}_{{\langle 23\rangle }_{y}}{\hat{u}}_{{\langle 34\rangle }_{z}}{\hat{u}}_{{\langle 45\rangle }_{x}}{\hat{u}}_{{\langle 56\rangle }_{y}}{\hat{u}}_{{\langle 61\rangle }_{z}}\) where the interactions to all other sites are missing While the second approach gives exact results for very slow holes which captures the experimentally relevant finite hopping regime we compare it to the slow-hole limit as well we add a kinetic term for nearest-neighbor hole hopping to the Kitaev Hamiltonian: which have an isotropic hopping; see derivation in the “Methods” section These are restricted to small system sizes and can hence only access a limited number of momenta for the hole spectral function Here we use tensor networks in the form of matrix product states (MPS) which allow us to study larger systems on a cylinder with length Lx and circumference Ly Details on the numerical methods are provided in the “Methods” section This motivates us to investigate the behavior of a single hole that is inserted into the spin-liquid ground state with FM couplings we can extract typical product-state configurations of the MPS and the corresponding probabilities in the computational basis For this basis \(\{\left\vert s\right\rangle \equiv \left\vert {s}_{1}{s}_{2}\ldots \,\right\rangle ;{s}_{i}\in (\uparrow ,\downarrow ,\circ )\}\) the Fock space configuration \(\left\vert s\right\rangle\)) is p(s) = ∣cs∣2 We can use this for sampling the expectation value of an operator O with a subset \({{{\mathcal{S}}}}\) of basis states where O is diagonal in the corresponding basis Note that particle number conservation enforces precisely one hole per snapshot. Examples of such snapshots are displayed in Fig. 2a which are formed only from the spin background of the Kitaev spin liquid due to quantum fluctuations we observe larger FM clusters around the site where the hole is located The anisotropic spin interactions Jz/J = 2.5 used in our simulations favor FM correlations in z-basis which is used as the Fock basis to sample the snapshots the snapshots directly depict the fluctuating FM order due to the energy constraints within unitary time evolution the FM clusters cannot reach the ground-state magnetization value M0 as the hole excites the system We also find that increasing t or doping a finite but small hole density instead of a single hole leads to the same magnetization for larger system sizes where \(\left\vert {\psi }_{0}\right\rangle\) denotes the Kitaev spin-liquid ground state For numerical details and additional data regarding convergence in bond dimension We shift all energies by a constant μ that is computed from the energy difference between the ground state without a hole and with a single hole it corresponds to the Mott gap of the insulator and all hole excitations have to be outside that gap we cannot gain additional insights from looking at the spin-resolved spectra numerically spin-asymmetry may be used in experiments to characterize perturbations to the considered model Jz/J = 2.5 and t/J = 3.0 along the three distinct cuts in the Brillouin zone (see inset in the bottom row) shows significant resemblance with the spectrum of a free hole hopping on a honeycomb lattice (green lines) Both the energy dispersion (top row) and the spectral weight (bottom row) agree well with the free hole a When hopping from the initial site to the response site r the hole can move along different paths contributing to the dynamics at the corresponding times b The correlations 〈nrWp〉 between a hole at a fixed site r and all plaquettes p get destroyed along the paths as time evolves from τ1 to τ3 Shown data is for ferromagnetic Kitaev couplings J > 0 for ferromagnetic Kitaev couplings J > 0 the hole does not separate into fractionalized quasiparticles paving the way for a dynamically emerging ferromagnetic state only an infinitely fast hole is expected to give rise to an extensive FM polarization of the system shows that already for intermediate hopping strength significant FM polarization clouds can be observed we focus on the specific gapped case of Jz/J = 2.5 and t/J = 3.0 The same phenomena also occur for other ratios of t/J; data are shown in the “Methods” section we also investigate the dynamics of a hole inserted into a Kitaev spin-liquid ground state with antiferromagnetic couplings Nagaoka’s theorem is also applicable in this case the hopping constant t required for that may be very large because the gain in the kinetic energy of the hole has to be balanced with AFM spin fluctuations we focus on the strong coupling regime t > ∣J∣ but avoid the Nagaoka FM for all considered values of the hopping strength Jz/J = 2.5 and t/∣J∣ = 3.0 along the three distinct cuts in the Brillouin zone (see inset on the top right) b Zoom-in on the low-energy part of the spectrum shows several flat dispersions which agree with the parton mean-field description (green dashed and dotted lines) c The spectral density \(D(\omega )=\frac{1}{{L}_{x}{L}_{y}}{\sum }_{{{{\bf{k}}}}}A({{{\bf{k}}}},\omega )\) for antiferromagnetic (AFM J < 0) and ferromagnetic (FM J > 0) Kitaev couplings d The FM cluster size Nc increases for FM couplings but stays constant for AFM couplings as further illustrated by the fits (dashed lines) we perform a mean-field decoupling to extract the separate spectra of these fractionalized excitations; see “Methods” section for more details Overall, the parton mean-field theory captures the correct energies at which responses in the low-energy part of the hole spectrum are expected but fails to predict the spectral weight distribution; see Fig. 11 in the “Methods” section the mean-field ansatz does not encompass all the relevant correlations and interplay between the charge and spin degrees of freedom This shortcoming may be associated with the strong holon renormalization leading to effective hoppings \({t}_{{{{\rm{eff}}}}}^{z}\,\approx \,0.18\,t\) along the z-bonds and \({t}_{{{{\rm{eff}}}}}^{x,y}\,\approx \,0.11\,t\) along the x- and y-bonds; see “Methods” section for more details the energy scales of spinons and holons are mixed but may be separated for even more extreme ratios t/∣J∣ which we cannot reliably access numerically the cluster size increases over time in the case of FM couplings the cluster size remains constant at a low value for AFM couplings These observations let us conclude that for AFM couplings leading to the intricate dynamical interplay between the (fractionalized) excitations The main reason for that is the strong renormalization of the hopping strength teff which is no longer larger than the spin energy scales the hole spectrum shows signatures of flat spinon bands that are a direct consequence of the underlying Kitaev spin liquid and can therefore be used as a characteristic of this phase in ARPES experiments the spin is not removed from the “hole site” but all interactions with neighboring spins are just turned off We now want to investigate this limit to understand the limitations and merits compared to our numerical simulations We start with the description of a stationary hole t = 0 and solve the quadratic Hamiltonian Eq. (4) by doubling the number of Majorana fermions to obtain complex fermions: where \({\underline{\chi }}_{i}^{0}\) are copies of the original Majorana fermions18 We introduce a hole at site j0 by switching off all interactions at the corresponding bonds Let \(\left\vert {{\Omega }}\right\rangle\) and \(\left\vert \tilde{{{\Omega }}}\right\rangle\) denote the ground states of the pure Kitaev model and the one with a stationary hole We can compute the corresponding quasiparticle weight of the hole spectrum \(Z=| \left\langle \tilde{{{\Omega }}}| {{\Omega }}\right\rangle {| }^{2}\) directly on the same cylinder geometry that we use for the MPS time evolution To obtain the full spectrum for a stationary hole we expand the hole Hamiltonian in the eigenbasis at half-filling \({\tilde{H}}_{d}^{{j}_{0}}={\sum }_{i}{\tilde{\varepsilon }}_{i}\left\vert {\tilde{\alpha }}_{i}\right\rangle \left\langle {\tilde{\alpha }}_{i}\right\vert\) The spectral density \(D(\omega )=\frac{1}{{L}_{x}{L}_{y}}{\sum }_{{{{\bf{k}}}}}A({{{\bf{k}}}},\omega )\) obtained from MPS time evolution (purple) is compared with the slow-hole approximation (green) as described in the main text and sketched in the inset of the last panel We fix antiferromagnetic couplings J < 0 Jz/J = 2.5 and vary t/∣J∣ from 0.0 (exact stationary hole limit) to 3.0 (fast holes) a different energy scale of the x-axis is used in order to show the whole spectrum This can be intuitively understood from the isolated dimer limit Jz/J → ∞ where the ground state consists of dimers on the z-bonds \(({\left\vert \uparrow \downarrow \right\rangle }_{z}+{\left\vert \downarrow \uparrow \right\rangle }_{z})/\sqrt{2}\) Inserting either an up- or down-hole on one lattice site will break up the corresponding dimer The hole can hop freely back and forth along the same dimer on the z-bond \({\vert \uparrow \circ \rangle }_{z}\to {\vert \circ \uparrow \rangle }_{z}\) Hopping along the x- or y-bonds requires hopping to a neighboring dimer we modify this ansatz and allow for the bond strength to vary over all lattice sites ρ ↦ ρ({j}) The interpretation follows straightforwardly from the stationary picture different bonds will be modified depending on the probability of finding the hole at the corresponding site According to the hole expectation value 〈nj〉 To describe a local hole that spreads dynamically we approximate the time evolution by step-wise adjusting 〈nj(τ)〉 and where 〈nj(τ)〉 is determined by a free hopping hole with tx = t/2 and tz = t according to the slow hole prediction we get a Trotterized time evolution for the response function with step-size δ = τ/N where we introduce hole operators \({a}_{j}^{({\dagger} )}\) which locally switch off the couplings E0 is the ground state energy of the undoped Kitaev model and for each Hn (n = 1 N) we modify ρ as described before according to the corresponding hole expectation at time n ⋅ δ Since all Hn are quadratic fermionic Hamiltonians we can diagonalize them \({H}_{n}={\sum }_{i}{\varepsilon }_{i}^{(n)}\left\vert {\alpha }_{i}^{(n)}\right\rangle \left\langle {\alpha }_{i}^{(n)}\right\vert\) By insertion of identities after each time step the correlation function simplifies to a product of overlaps again we do not need to sum over all eigenstates \(\left\vert {\alpha }_{{i}_{n}}^{(n)}\right\rangle\): Because the Hamiltonians change only slightly from one time step to the other it is sufficient to take the overlap with only the ground states \(\left\vert {{{\Omega }}}^{(n)}\right\rangle\) We find that indeed the overlaps are very close to one we can simplify the time-dependent correlations to ω) is then computed by spatial and temporal Fourier transformations of the time-dependent correlation functions similar to the evaluation of the data from the MPS time evolution We compare the slow-hole approximations to the spectra obtained from the full MPS time evolution in Fig. 6 the analytic description of stationary holes is exact and we find that the spectra indeed are almost identical; demonstrating that our numerical results are well converged as discussed above we see a remarkable resemblance between the slow-hole limit and the MPS data Note that the formally required limit for the approximation to be valid is \(t/| J|\ \ll \,{(J/{J}_{z})}^{4}\,\approx \,0.025\) This ensures that the hole does not couple to the flux excitation of the bulk the hole-flux interactions are not relevant to the shape of the spectrum the hole is best described by vacancy sites that spread slowly over the whole system and modify the Kitaev spin-liquid ground state only slightly Upon increasing the hopping strength t/∣J∣ ≳ 0.8 the general shape between both curves is still similar but small deviations between peak positions occur for t/∣J∣ ≳ 1.0 additional peaks in the MPS spectrum appear This suggests that further modes in the model with significant spectral weight are excited Since this can include complex interactions between the hole and flux or matter excitations in the Kitaev model the simple ansatz for the slow holes cannot capture these features anymore meaning that the slow-hole picture breaks down We find that the overall bandwidth is not given by the renormalized hoppings t/2 as predicted from the slow hole ansatz but by the full bandwidth ~t we see a shift of spectral weight towards low energies which transition into a broad continuum at high energies and the parton ansatz becomes more reasonable So far, we focused on the momentum-resolved and energy-resolved hole spectrum as measured by ARPES experiments, Eq. (8) or their sum rules we will consider the spatially averaged local hole spectrum that is measurable with scanning tunneling microscopy (STM): where tunneling occurs directly in and out of the spin liquid layer by injecting mobile holes The local spectral function S(ω), Eq. (18) as measured by scanning tunneling microscopy (STM) is shown for ferromagnetic couplings J > 0 and antiferromagnetic couplings J < 0; both with Jz/J = 2.5 and t/∣J∣ = 3.0 The inset focuses on the low energy regime that is compared to the parton ansatz (green line) Our results reveal an intriguing behavior of a mobile hole doped into the Kitaev spin-liquid ground state We looked at the real-time dynamics of the hole spreading and studied the energy and momentum resolved hole spectra as measured by ARPES as well as the local spectral function Our simulations were carried out on finite cylinder geometries using tensor network methods we expect at least qualitatively similar behavior for the 2D limit The ARPES response is drastically different for ferromagnetic (FM) and antiferromagnetic (AFM) Kitaev couplings between neighboring spins The FM case is characterized by the formation of clusters of aligned spins leading to a dynamical Nagaoka ferromagnet that allows for coherent hole hopping the STM spectra show coherent dynamical features even at low energies AFM couplings robustly show multiple dispersionless features at low energies we find that the hole does not couple to any other excitations and is described as a vacancy that modifies the spin liquid flux and matter excitations of the Kitaev model become relevant and significantly alter the spectral function Understanding these modifications is challenging since the exact solution of the Kitaev model is lost and the hole interacts non-trivially with the spin background A parton mean-field ansatz gives some insights into the spectral responses for AFM couplings but fails to reproduce the proper spectral weight along the different momentum cuts in the Brillouin zone interactions beyond a parton mean-field theory are required in the considered parameter regime and may be investigated in more detail in future studies we assume the holon and spinon to be deconfined a FM spin exchange J results in a FM ground state on the square lattice The single-hole problem can be solved exactly since hole hopping leaves the spin background unmodified and describes the hopping of a free hole This is in sharp contrast to our results for the Kitaev spin liquid where the ground state does not have any order initially the effective free-hole-like response in the spectral function they may shed light on which perturbations can stabilize topological superconductivity beyond the mean-field approach In the promising candidate materials exhibiting strong Kitaev interactions such as 5d iridate compounds Na2IrO3 and 4dα-RuCl3 the partially filled d5 orbital is split into eg and t2g (\(\left\vert xy\right\rangle\) and \(\left\vert zx\right\rangle\)) orbitals the t2g multiplet is further divided into a Jeff = 3/2 quartet and a Jeff = 1/2 Kramers doublet The low-energy physics is dominated by the Jeff = 1/2 doublet with a reduced bandwidth we would like to demonstrate the relation between hybridized pseudo-spins and physical spins in realistic materials such as Na2IrO3 The Kramers doublet, \(({c}_{\uparrow }^{{\dagger} },{c}_{\downarrow }^{{\dagger} })\), can be expressed in terms of t2g orbitals as72 where \({d}_{m,\sigma }^{{\dagger} }\) is an electron for orbital m ∈ (xy ↓) and the lattice site index has been omitted We can introduce a vector of electrons \({{{{\bf{d}}}}}_{}^{{\dagger} }=\left({d}_{xy,\uparrow }^{{\dagger} },{d}_{xy,\downarrow }^{{\dagger} },{d}_{yz,\uparrow }^{{\dagger} },{d}_{yz,\downarrow }^{{\dagger} },{d}_{zx,\uparrow }^{{\dagger} },{d}_{zx,\downarrow }^{{\dagger} }\right)\) and define a projector P Then we obtain a compact form of \(({c}_{\uparrow }^{{\dagger} },{c}_{\downarrow }^{{\dagger} })={{{{\bf{d}}}}}_{}^{{\dagger} }P\) The physical spin operators at site j are defined as Now we would like to project the spin to the low-energy Jeff = 1/2 bands we first need to find the null space corresponding to the projector P can be obtained by extracting the eigenstates of zero modes of PP† those zero modes of PP† correspond to the basis of the high-energy Jeff = 3/2 quartet and we denote those modes as \(({c}_{1}^{{\dagger} },...,{c}_{4}^{{\dagger} })\) one can express the electrons as \({{{{\bf{d}}}}}^{{\dagger} }={{{{\bf{c}}}}}^{{\dagger} }{(P+{P}_{\perp })}^{{\dagger} }\) where \({{{{\bf{c}}}}}^{{\dagger} }\equiv ({c}_{\uparrow }^{{\dagger} },{c}_{\downarrow }^{{\dagger} },{c}_{1}^{{\dagger} },...,{c}_{4}^{{\dagger} })\) we can rewrite the physical spin operators in terms of c-fermions and after projecting into the low-energy doublet sector The tensor of the dynamical hole spectral function is thus defined as By viewing \({{{\mathcal{A}}}}({{{\bf{k}}}},\omega )\) as a 6 × 6 matrix it is related to the spectral function for c-fermions by a unitary transformation as \({{{\mathcal{A}}}}({{{\bf{k}}}},\omega )={(P+{P}_{\perp })}^{* }{{{\mathcal{F}}}}({{{\bf{k}}}},\omega ){(P+{P}_{\perp })}^{T}\) with H the Hamiltonian and E0 the ground-state energy We mainly focus on the excitations with energy being within EW Within the frequency regime of ω < EW (ℏ = 1) the orbital and spin resolved hole spectral function can be obtained by only computing the 2 × 2 spectral function for the pseudo spins \({F}_{\sigma ,{\sigma }^{{\prime} }}\) In the end, the energy- and momentum-resolved spectral function defined in the main text Eq. (8) is just the trace of the above matrix the only contributions come from terms that do not mix the different spins spin-resolved spectra provide only additional information when the material breaks spin-symmetry Numerical costs grow linearly in Lx but exponentially in Ly we restrict ourselves to cylinders with Ly = 4 unit cells (i.e. To reach the large bond dimensions of up to χ = 1000 required to obtain converged results we have utilized \({{{\rm{U}}}}(1)\times {{\mathbb{Z}}}_{2}\) symmetries for particle number and spin parity conservation we have first to use the more costly zip-up methods for a few time steps to avoid being stuck in a local minima before continuing with a variational truncation scheme with fixed MPS bond dimension χ Depending on the hole hopping we choose step size δτ = 0.05/ t for fast holes t/∣J∣ > 1.0 and δτ = 0.025/ ∣J∣ otherwise we compute a time evolution after injecting a hole into the ground state \(\left\vert {\psi }_{0}\right\rangle\) of the pure Kitaev model where j is a site in the middle of the cylinder We check that the cylinder is long enough (Lx = 20) such that excitations do not reach the boundaries on the simulated time scales to limit the boundary effects To access the spectral function, we employ established MPS methods76 we obtain an MPS approximation for the ground state without hole \(\left\vert {\psi }_{0}\right\rangle\) through the DMRG algorithm The calculation is performed on a finite Ly × Lx system we compute the time-dependent correlation function This has to be contrasted to the usual definition of the sublattice Fourier transformation which is for instance used to compute the dispersion relations for the parton mean-field ansatz below For Eq. (31), a unique inverse Fourier transformation exists. In contrast, for the operator in Eq. (30) we have to distinguish between k ∈ 1.BZ and k ∉ 1.BZ These two cases are related to the sublattice Fourier transformation by: we use i = j and sum over the contributions from the two sublattices without the spatial Fourier transformation but still keeping the linear prediction and Gaussian envelope Jz/J = 2.5 and t/J = 3.0 at the Γ point is converged for larger values of the maximal MPS bond dimension χ > 500 but still shows considerable deviations for χ = 300 We present additional spectra for different parameters. First, we investigate the spectra for different hopping parameters t when considering ferromagnetic (J > 0) and antiferromagnetic (J < 0) coupling constants. The resulting spectra are shown in Fig. 9. b For ferromagnetic Kitaev couplings (J > 0) the spectrum mainly consists of the response of a free hole (green lines) d Antiferromagnetic Kitaev couplings (J < 0) show only slight changes at low energies for different values for t/∣J∣ Spectra are compared to the parton ansatz; dashed and dotted lines for spinon excitations along x- or y-bonds and z-bond Note that all energy scales are in units of t For the ferromagnetic case, Fig. 9a, b we observe only slight changes in the distribution of spectral weight with varying hopping parameters t further supporting that the spectrum is dominated by free hole hopping Increased hopping leads to a higher contribution from the kinetic energy which further stabilizes the ferromagnetic order and the associated free coherent hole motion This could indicate an additional interplay between spinons and holons We note that even for these comparatively large values of the hopping which is renormalized down by a factor of five to ten is still in the same order as the exchange it is very difficult to numerically reach a true strong coupling limit in which the hole dynamics is effectively much faster than the spin dynamics a For ferromagnetic Kitaev couplings (J > 0) the main contribution to the spectrum resembles the response of a free hole (green lines) b For antiferromagnetic Kitaev couplings (J < 0) the first flat features can be described by the parton ansatz (dashed green lines) we can rewrite the Kitaev model in terms of these spinons: where the parameters \(\tilde{J}\), Δ are determined self-consistently79 factorizes into a product of the holon and the spinon part After Fourier transformation to momentum space the spectrum is given by the convolution of the individual holon and spinon spectral functions Ah(k the hopping gets renormalized to quite small effective values the spinons and holons no longer have separate energy scales preventing a clear distinction between the two in the spectrum for reasonable parameters Spectral function A(k, ω) at low energies for antiferromagnetic J < 0, Jz/J = 2.5 and t/∣J∣ = 3.0 (a) from MPS time evolution and (b) from parton convolution; see Eq. (38) Dashed/ dotted lines correspond to energies of spinons for bond excitations along x- and y-bonds/ z-bonds added to the van Hove points of the holons which are expected to dominate the spectral response The MPS spectrum features similar flat bands as well; see Fig. 11a The lower one is at the same energy as the parton construction and may be interpreted as the lowest spinon mode plus the van Hove singularity of the holon the spectral weight distribution shows qualitatively different behavior indicating that there are complex interactions between holon and spinon that must be treated beyond the simple mean-field level the MPS spectrum shows dispersive features as well which have some resemblance of the parton ansatz the MPS spectra carry much more spectral weight at these energies than the parton predictions Mean-field theory of spin-liquid states with finite energy gap and topological orders Anyons in an exactly solved model and beyond Mott Insulators in the strong spin-orbit 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pairing and electronic dimerization instabilities in the doped Kitaev–Heisenberg model Possible fermi liquid in the lightly doped Kitaev spin liquid Spectral functions for the tomonaga-luttinger model Charge-spin separation and the spectral properties of luttinger liquids International Series of Monographs on Physics (Clarendon Press Theory of a continuous Mott transition in two dimensions Mott transition between a spin-liquid insulator and a metal in three dimensions Spin-charge separation in two-dimensional frustrated quantum magnets Hole spectral function of a chiral spin liquid in the triangular lattice Hubbard model Strongly correlated electronic systems with one hole: dynamical properties Small-polaron theory of doped antiferromagnets Evidence for composite nature of quasiparticles in the 2D T-J model Evidence for quasiparticle decay in photoemission from underdoped cuprates Single-hole dynamics in the T-J model on a square lattice Single-hole spectral function and spin-charge separation in the T-J model Dynamical formation of a magnetic polaron in a two-dimensional quantum antiferromagnet Parton theory of ARPES spectra in anti-ferromagnetic Mott insulators Hole in the two-dimensional ising antiferromagnet: origin of the incoherent spectrum Kinetic magnetism in triangular moiré Materials Frustration- and doping-induced magnetism in a Fermi-Hubbard simulator Observation of Nagaoka Polarons in a Fermi-Hubbard Quantum Simulator Directly imaging spin polarons in a kinetically frustrated Hubbard system Quantum walk in degenerate spin environments Quantum correlations at infinite temperature: the dynamical Nagaoka effect ARPES study of the Kitaev candidate α-RuCl3 Electronic structure of the Kitaev material α-RuCl3 probed by photoemission and inverse photoemission spectroscopies Na2IrO3 as a Novel Relativistic Mott Insulator with a 340-meV Gap Observation of metallic surface states in the strongly correlated Kitaev-Heisenberg candidate Na2IrO3 Spectrum of the hole excitation in spin-orbit Mott insulator Na2IrO3 Hole propagation in the Kitaev–Heisenberg model: from quasiparticles in quantum Neel states to non-Fermi liquid in the Kitaev phase Angle-resolved photoemission studies of the cuprate superconductors Topological superconductivity in Kondo–Kitaev model Spin waves and revised crystal structure of honeycomb iridate Na2IrO3 Breakdown of magnons in a strongly spin-orbital coupled magnet Perfect sampling with unitary tensor networks Kinetic Ferromagnetism and Topological Magnons of the Hole-Doped Kitaev Spin Liquid Density matrix renormalization group analysis of the Nagaoka polaron in the two-dimensional T-J model Angle-resolved photoemission spectroscopy with quantum gas microscopes Direct evidence for dominant bond-directional interactions in a honeycomb lattice iridate Na2IrO3 Materials design of Kitaev spin liquids beyond the Jackeli-Khaliullin mechanism Dynamics of a two-dimensional quantum spin liquid: signatures of emergent majorana fermions and fluxes Local probes for charge-neutral edge states in two-dimensional quantum magnets Tunneling spectroscopy of quantum spin liquids Vacancy spectroscopy of non-Abelian Kitaev spin liquids Precursor of pair-density wave in doping Kitaev spin liquid on the honeycomb lattice Quantum spin hall effect in a transition metal oxide Na2IrO3 Efficient numerical simulations with Tensor Networks: Tensor Network Python (TeNPy) Time-evolving a matrix product state with long-ranged interactions Time-evolution methods for matrix-product states Single-hole properties of the T-J model on the honeycomb lattice Spectral function for the S = 1 Heisenberg antiferromagnetic chain SU(2) slave fermion solution of the Kitaev honeycomb lattice model Kadow, W., Jin, H.K., Knolle, J., Knap, M. Zenodo entry for: Single-hole spectra of Kitaev spin liquids: From dynamical Nagaoka ferromagnetism to spin-hole fractionalization (2023). https://doi.org/10.5281/zenodo.8363616 Download references We thank Wonjune Choi for insightful discussions We acknowledge support from the Deutsche Forschungsgemeinschaft (DFG German Research Foundation) under Germany’s Excellence Strategy–EXC–2111–390814868 and TRR 360 - 492547816 and from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programme (Grant Agreement No which is supported by the Bavarian state government with funds from the Hightech Agenda Bayern Plus We thank the Nanosystems Initiative Munich (NIM) funded by the German Excellence Initiative and the Leibniz Supercomputing Centre for access to their computational resources Open Access funding enabled and organized by Projekt DEAL Munich Center for Quantum Science and Technology (MCQST) performed the numerical and analytical calculations and evaluated the data calculated the orbital structure of the spectral function All authors contributed to analyzing the data Download citation DOI: https://doi.org/10.1038/s41535-024-00641-7 Your browser does not support JavaScript, or it is disabled．Please check the site policy for more information Niigata Prefecture--The Nagaoka Fireworks Festival a spectacular event that draws hundreds of thousands of spectators here each year on Aug will raise seating prices for general audiences One of Japan’s three largest fireworks shows the awe-inspiring pyrotechnics display originally began to console the souls of residents who had been killed in Allied air raids The festival started charging for all seats in 2022 to prevent the spread of the novel coronavirus It continued the paid seating system last year as a precaution against crowd crushing and heatstroke the prices for local residents and general spectators had been the same this year fees will be raised for general spectators due to increased labor costs for security guards and other expenses Prices for local residents will remain unchanged so that community members can enjoy the spectacular show According to the Nagaoka Fireworks Foundation and the city government larger crowds are expected this year because the festival falls on a Friday and Saturday The organizers will increase the number of seats to about 170,000 on both nights to accommodate larger crowds there are many souls to commemorate at the fireworks festival as this is the 20th anniversary of the Niigata Chuetsu Earthquake and the July 13 flooding in the prefecture that same year The Noto Peninsula earthquake also occurred this year on New Year’s Day while wars are ongoing in Ukraine and elsewhere “We want to promote our quest for building a peaceful world as we console the souls of victims show appreciation to the support we have received and raise hopes for reconstruction,” said Nagaoka Mayor Tatsunobu Isoda Tickets for general spectators will be sold online from May 27 For more information, visit the official website at (https://www.nagaokahanabi.jp/international-visitors.html) Festivals that planned to return now face tough calls as cases rise VOX POPULI: Remembering artist Kiyoshi Yamashita who loved fireworks Akita’s famed fireworks festival takes peace as its theme this year Fireworks displays are back this summer after COVID-19 hiatus Fireworks paint night sky over Osaka for 1st time in 3 years Information on the latest cherry blossom conditions Please right click to use your browser’s translation function.) A series based on diplomatic documents declassified by Japan’s Foreign Ministry Here is a collection of first-hand accounts by “hibakusha” atomic bomb survivors chefs and others involved in the field of food introduce their special recipes intertwined with their paths in life A series about Japanese-Americans and their memories of World War II In-house News and Messages No reproduction or republication without written permission Metrics details Finding the optimal attainable precisions in quantum multiparameter metrology is a non-trivial problem One approach to tackling this problem involves the computation of bounds which impose limits on how accurately we can estimate certain physical quantities One such bound is the Holevo Cramér–Rao bound on the trace of the mean squared error matrix The Holevo bound is an asymptotically achievable bound when one allows for any measurement strategy including collective measurements on many copies of the probe we introduce a tighter bound for estimating multiple parameters simultaneously when performing separable measurements on a finite number of copies of the probe This makes it more relevant in terms of experimental accessibility We show that this bound can be efficiently computed by casting it as a semidefinite programme We illustrate our bound with several examples of collective measurements on finite copies of the probe These results have implications for the necessary requirements to saturate the Holevo bound Nagaoka’s bound is not an explicit bound—it requires a further a non-trivial minimisation we generalise the Nagaoka bound to estimating more than two parameters and we call this generalised bound the Nagaoka–Hayashi bound This bound applies to separable measurements on a finite number of copies of the probe state is only asymptotically attainable in general We further show that the minimisation required in the Nagaoka–Hayashi bound can computed using a semidefinite programme We illustrate our results with two examples which highlight some of the interesting features of finite copy metrology which are inaccessible with conventional techniques we are able to find the positive operator valued measure (POVM) which saturates the bound however whether this is always possible remains an open question Consider an n-parameter family of states \(\left\{{S}_{\theta }| \theta \in {{\Theta }}\subseteq {{\mathbb{R}}}^{n}\right\}\) in a finite d dimensional Hilbert space \({{\mathcal{H}}}_{q}\) with \(\theta ={\left({\theta }_{1},\ldots ,{\theta }_{n}\right)}^{\top }\) denoting the n independent true values that we wish to estimate Let \({{\Pi }}={({{{\Pi }}}_{1},\ldots ,{{{\Pi }}}_{M})}^{\top }\) be a column vector of M POVM elements where (⋅)⊤ denotes partial transpose with respect to the classical subsystem Each outcome m assigns an estimated value for θj through the classical estimator function \({\hat{\theta }}_{jm}\) The standard measure of estimation error when restricted to separable measurements is through the n-by-n MSE matrix \({{\mathsf{V}}}_{\theta }({{\Pi }},\hat{\theta })\) with entries The notation \({\rm{Tr}}[\cdot ]\) in serif font is used to represent the trace of an operator in \({{\mathcal{H}}}_{q}\) hereafter we drop the argument and write the MSE matrix as Vθ We aim to minimise the trace of the MSE matrix under the condition that our estimates are locally unbiased where \({\mathsf{Tr}}[\cdot ]\) denotes the trace of a classical matrix in \({{\mathcal{H}}}_{c}\) TrAbs A is the sum of the absolute values of the eigenvalues of the operator A and \(X={({X}_{1},{X}_{2},...,{X}_{n})}^{\top }\) is a vector of Hermitian estimator observables Xj that satisfy the locally unbiased condition at θ the Nagaoka bound can be generalised to more than two parameters This result is stated as the following theorem Let Vθ be the MSE matrix of an unbiased estimate of θ for a separable measurement on a model Sθ where \({{\mathbb{S}}}_{\theta }={1}_{n}\otimes {S}_{\theta }\) and \({\mathbb{L}}\) is an n-by-n matrix of Hermitian operators \({{\mathbb{L}}}_{jk}\) We use the symbol \({\mathbb{T}}{\rm{r}}[\cdot ]\) to denote trace over both classical and quantum systems over both \({{\mathcal{H}}}_{c}\) and \({{\mathcal{H}}}_{q}\) We call this bound the Nagaoka–Hayashi bound the Nagaoka–Hayashi bound is not an explicit bound cNH can be computed as a semidefinite programme the Holevo bound is a tight bound for collective measurements in the asymptotic limit Since the conditions in the Nagaoka–Hayashi bound \({{\mathbb{L}}}_{jk}={{\mathbb{L}}}_{kj}\) Hermitian implies \({\rm{Tr}}[{{\mathbb{S}}}_{\theta }{\mathbb{L}}]\) real symmetric and \({\mathbb{L}}\ge X{X}^{\top }\) implies \({\rm{Tr}}[{{\mathbb{S}}}_{\theta }{\mathbb{L}}]\ge {\rm{Tr}}[{{\mathbb{S}}}_{\theta }X{X}^{\top }]\) it is clear that the Nagaoka–Hayashi bound is more restrictive and hence is more informative compared to the Holevo bound The second related bound concerns estimation of physical observables. In this setting, the operators Xj are given to us as Hermitian operators and the task is to estimate the expectation values \({\rm{Tr}}[{S}_{\theta }{X}_{j}]={x}_{j}\). This situation is common, for example, in state tomography. Here, in place of the parameter-MSE matrix Eq. (1) where we require the classical estimator \(\hat{x}\) and POVM Π to satisfy We rewrite the elements of the MSE matrix as where the MSE-matrix operator \({{\mathbb{L}}}_{\theta }({{\Pi }},\hat{\theta })\) is an n-by-n matrix with operator elements We introduce a classical matrix ξ with elements \({\xi }_{jm}:= {\hat{\theta }}_{jm}-{\theta }_{j}\) so that where we have set n = 3 to simplify the presentation The generalisation to arbitrary n is straightforward it is clear that \({{\mathbb{L}}}_{\theta }\) is an operator on the extended Hilbert space \({{\mathcal{H}}}_{c}\otimes {{\mathcal{H}}}_{q}\) it is useful to write \({{\mathbb{L}}}_{\theta }\) in the following form: where M is the number of POVM outcomes and \({{\Xi}}_{i,j}={\xi_i,j} \otimes 1\) We can also introduce the following extension to Sθ \({{\mathbb{S}}}_{\theta }=1 \otimes {S_\theta }\) so that the expression for the MSE matrix can be written as \({{\mathsf{V}}}_{\theta }={\rm{Tr}}\left[{{\mathbb{S}}}_{\theta }{{\mathbb{L}}}_{\theta }\right]\) Suppose the optimal POVM and unbiased estimator have been found and are given by Π and \({X}_{j}^{* }=\mathop{\sum}\limits_{m}{\xi }_{jm}{{{\Pi }}}_{m}\ ,\quad \,\text{for}\,j=1,\ldots ,n\) which leads to the optimal MSE We use asterisk to denote the optimal values and optimal operators we can construct the estimator matrices \({X}_{j}^{* }=\mathop{\sum}\limits_{m}{\xi }_{jm}{{{\Pi }}}_{m},\quad \,\text{for}\,j=1,\ldots ,n\) so that Comparing the above with Eq. (14) and using the result which holds because Πj are positive operators that sums up to 1 (see Proposition II.9.1 of Holevo52) we arrive at \({{\mathbb{L}}}_{\theta }^{* }\ge {X}^{* }{X}^{* \top }\) In the two-parameter case, we show in Supplementary Note 2 that cNH reduces to the original Nagaoka bound cN in Eq. (3) we are interested in minimising the weighted sum of the covariances which can be formalised with a positive weight matrix W ≥ 0 and minimising \({\mathsf{Tr}}[{\mathsf{W}}\ {{\mathsf{V}}}_{\theta }]\) This problem can be handled by a suitable reparametrisation of the model which is presented in Supplementary Note 3 The Nagaoka–Hayashi bound is not an explicit bound as it still requires a minimisation over \({\mathbb{L}}\) and X Our next result concerns with the computation of this minimisation Since \({\mathbb{L}}-X{X}^{\top }\) is the Schur’s complement of the identity operator in \(\left(\begin{array}{ll}{\mathbb{L}}&X\\ {X}^{\top }&1\end{array}\right)\) the condition \({\mathbb{L}}\ge X{X}^{\top }\) is equivalent to \(\left(\begin{array}{ll}{\mathbb{L}}&X\\ {X}^{\top }&1\end{array}\right)\ge 0\) cNH can be written as the semidefinite programme where \({{\mathbb{L}}}_{jk}={{\mathbb{L}}}_{kj}\) Hermitian and Xj Hermitian satisfying the conditions Eq. (4) for local unbiasedness The conversion to a standard semidefinite programme is performed in Supplementary Note 4 We also show in the same Supplementary Note that the worst case computational complexity for solving the SDP to an accuracy ϵ is \(O\left({(nd)}^{3/2}{\mathrm{log}}\,(1/\epsilon )\right)\) That the inferred solutions are indeed optimal can then be verified by checking that the values for the primal and dual programmes coincide we present the dual solutions in Supplementary Note 7 We consider the maximally entangled two-qubit state \(\left(\left|01\right\rangle +\left|10\right\rangle \right)/\sqrt{2}\) as a probe The first qubit acts as a signal-probe which passes through a channel imparting three small rotations: θx The rotated probe is then subject to the phase damping channel \({\mathcal{E}}\) with a known damping strength ϵ The second idler qubit is stored in a perfect quantum memory and remains unaffected by the rotation or phase damping The resulting two-qubit state then has an approximate matrix representation in the computational basis as The partial derivatives of Sθ with respect to θ evaluated at θ = 0 are Let us start with the simple case when θy = θz = 0 and we are only estimating the single parameter θx the Holevo bound coincides with the Nagaoka–Hayashi bound and can always be saturated by a separable measurement the two bounds can be achieved by the estimator operator The optimal measurement that saturates this bound is a projective measurement on the four orthogonal eigenvectors of Xx This together with the estimation coefficients ξ = (1 The phase damping channel has no effect on the estimation precision for estimating the two parameters θx and θy when θz = 0 the Holevo and Nagaoka bounds no longer coincide The optimal matrices that achieve the minimum in the Holevo bound are found to be This means that there exists a sequence of collective measurements that can saturate a variance of vx = vy = 1 in the asymptotic limit the optimal Xx and Xy operators for the Nagaoka bound are different from those which optimise the Holevo bound For the Nagaoka bound the optimal matrices are Since there is a gap between the Holevo and Nagaoka bounds a separable measurement cannot saturate the Holevo bound—a collective measurement is required We show in Supplementary Note 5 that the Nagaoka bound is saturated by a family of five-outcome POVMs which gives vx = vy = 2/(2 − ϵ) This means that when restricted to separable measurements this is the smallest pair of variances possible we find the Holevo and Nagaoka–Hayashi bounds are We write down an explicit POVM that can approach cNH,3 with vx = vy = 2/(2 − ϵ) and vz → 1/(1−ϵ)2 in Supplementary Note 5 showing that this bound is tight For a maximally entangled two-qubit probe under the action of the phase damping channel we plot the Holevo bounds (solid lines) and Nagaoka–Hayashi bounds (dashed lines) in terms of average preciseness for estimating two (blue) and three (red) orthogonal rotation parameters simultaneously The Nagaoka–Hayashi bounds can be achieved by a separable measurement on a single probe while the Holevo bound requires a collective measurement on a possibly infinite number of copies The shaded area shows the gap between the two bounds the Holevo and Nagaoka–Hayashi bounds coincide and are equal to the two-parameter Holevo bound Both figures show how the gap between the Holevo and Nagaoka–Hayashi bounds shrinks as the number of copies of the probe state increases for estimating two (a) and three (b) parameters The Nagaoka–Hayashi bounds are rescaled by the number of copies of the probe state to account for the resources used This example demonstrates several interesting features of finite copy metrology we are able to definitively show that there exists a gap between the attainable precision with collective and separable measurements such a claim is not possible as any gap between a numerically optimal POVM and the Holevo bound may be a result of a deficiency in the numerical search as opposed to a physically meaningful gap as we are able to find a POVM which coincides with the Nagaoka–Hayashi bound we are able to say with certainty that this POVM is optimal we are able to investigate the attainability of the Holevo bound While it is known that the Holevo bound is asymptotically attainable it is not known how many copies of the probe state are required to get close to the Holevo bound to investigate this numerically with a POVM search is computationally very expensive The SDP presented circumvents this and allows us to investigate the attainability of the Holevo bound in a numerically efficient manner The measurement can be performed in two stages The first stage (green block) involves performing a projective measurement over the photon-number subspace to determine the number of photons lost The outcome of this measurement is then used to select a three-outcome POVM {Π(l)} for the second stage (black box) This measurement strategy saturates not only the Nagaoka bound We compute the Nagaoka bound for these states for different values of η with ϕ = 0 for N up to 14 using our SDP We find that the Nagaoka and Holevo bounds always coincide (up to numerical noise) This is to be expected when Π(ϕ) saturates the Holevo bound The fact that there is no gap between the Holevo and Nagaoka bound implies one of the two possibilities: either (i) the Nagaoka bound is not tight or (ii) separable measurements are always optimal for simultaneous estimation of ϕ and η The initial pure state \(\left|{\psi }_{\text{in}}\right\rangle =\mathop{\sum }\nolimits_{k = 0}^{N}\left|k,N-k\right\rangle {a}_{k}\) transforms in the lossy interferometer channel to the following state: The state Sϕ,η is a mixed state with rank N + 1 \({b}_{kl}=\left(\begin{array}{l}k\\ l\end{array}\right){\eta }^{k-l}{(1-\eta )}^{l}\) are the beam-splitter coefficients and pl represents the probability of losing l photons The partial derivatives of Sϕ,η share the same direct sum structure Each block can be measured separately but we cannot minimise vη + vϕ separately in each block This is because how much weight we attach to η or ϕ in one block will depend on how much information about them that we can get from the other blocks each l ≠ N block requires at most a three outcome POVM to saturate the Holevo bound so the total number of POVM outcomes needed is at most 3N + 1 The extra 1 comes from the l = N block where all photons are lost An analytic POVM that saturates the Holevo bound for the N = 1 case is given in Supplementary Note 6 The dual solution to the Nagaoka–Hayashi bound is presented in Supplementary Note 7 The numerical results show that the two bounds coincide for N up to and including 14 for any value of η We show in the main text that there exists a separable measurement that reaches the ultimate attainable precisions in this example a collective POVM cannot perform better than a separable POVM Different shades correspond to different η values with darker colours corresponding to larger η We have presented the Nagaoka–Hayashi bound for the simultaneous estimation of multiple parameters when restricted to separable measurements This ensures it is always tighter or just as tight as the Holevo bound A gap between the two bounds would imply that the Holevo bound cannot be achieved with a separable measurement and a collective measurement is needed to saturate it we have shown that the Nagaoka–Hayashi bound can be formulated as a semidefinite programme We have demonstrated our results with two examples These examples illustrate how our results can be used to recognise when a collective measurement is essential and when it is not Our results can be applied to many other problems in multiparameter quantum metrology and will help quantify the maximal advantage collective measurements have to offer a separable measurement is already optimal our SDP formalism can be immediately applied to such cases An interesting extension to this work would be to investigate examples which incorporate nuisance parameters The data that support the findings of this study are available from the corresponding author upon reasonable request The code that supports the findings of this study is available from the corresponding author upon reasonable request Quantum-enhanced measurements: beating the standard quantum limit Enhanced sensitivity of the LIGO gravitational wave detector by using squeezed states of light Quantum-mechanical noise in an interferometer Ultimate quantum limits for resolution of beam displacements Experimental quantum-enhanced estimation of a lossy phase shift Quantum phase estimation with lossy interferometers Quantum theory of superresolution for two incoherent optical point sources Resolving starlight: a quantum perspective Quantum-limited fiber-optic phase tracking beyond π range Quantum-enhanced positioning and clock synchronization Quantum improvement of time transfer between remote clocks The minimum variance of estimates in quantum signal detection Minimum mean-squared error of estimates in quantum statistics Generalized uncertainty relations and efficient measurements in quantum systems Quantum sensing for dynamical tracking of chemical processes Multiparameter quantum metrology of incoherent point sources: towards realistic superresolution Compatibility in multiparameter quantum metrology Uncertainty and trade-offs in quantum multiparameter estimation Multi-parameter estimation beyond quantum Fisher information Quantum state estimation with nuisance parameters Achieving quantum precision limit in adaptive qubit state tomography Entangling measurements for multiparameter estimation with two qubits Loss-tolerant quantum dense metrology with SU(1 Deterministic realization of collective measurements via photonic quantum walks Quantum enhanced multiple phase estimation Optimal estimation of joint parameters in phase space Tradeoff in simultaneous quantum-limited phase and loss estimation in interferometry Gaussian systems for quantum-enhanced multiple phase estimation Quantum enhanced estimation of a multidimensional field On super-resolution imaging as a multiparameter estimation problem Optimal measurements for simultaneous quantum estimation of multiple phases Explicit formula for the Holevo bound for two-parameter qubit-state estimation problem Reaching for the quantum limits in the simultaneous estimation of phase and phase diffusion A perspective on multiparameter quantum metrology: from theoretical tools to applications in quantum imaging Accessible precisions for estimating two conjugate parameters using Gaussian probes On quantumness in multi-parameter quantum estimation Geometric perspective on quantum parameter estimation Parameter estimation of qubit states with unknown phase parameter Ultimate precision of joint quadrature parameter estimation with a Gaussian probe A tight Cramér–Rao bound for joint parameter estimation with a pure two-mode squeezed probe Asymptotic Theory of Quantum Statistical Inference: Selected Papers (World Sci. Multiple-parameter quantum estimation and measurement of nonselfadjoint observables Probabilistic and Statistical Aspects of Quantum Theory Evaluating the Holevo Cramér-Rao bound for multiparameter quantum metrology Tight bounds on the simultaneous estimation of incompatible parameters A new approach to the Cramér-Rao-type bound of the pure-state model Local asymptotic normality for finite dimensional quantum systems Quantum local asymptotic normality based on a new quantum likelihood ratio Attaining the ultimate precision limit in quantum state estimation A new approach to Cramer–Rao bounds for quantum state estimation In Asymptotic Theory of Quantum Statistical Inference: Selected Papers Originally published as IEICE Technical Report A generalization of the simultaneous diagonalization of Hermitian matrices and its relation to quantum estimation theory On simultaneous measurement of noncommutative observables In Development of Infinite-Dimensional Non-Commutative Anaysis Uncertainty relation revisited from quantum estimation theory Yalmip: a toolbox for modeling and optimization in matlab in 2004 IEEE International Conference on Robotics and Automation (IEEE Cat ApS, M. The MOSEK Optimization Toolbox for MATLAB Manual. Version 9.0 http://docs.mosek.com/9.0/toolbox/index.html (MOSEK ApS Improvement of frequency standards with quantum entanglement Decoherence of quantum superpositions through coupling to engineered reservoirs Quantum Fisher information of the Greenberger-Horne-Zeilinger state in decoherence channels Information geometrical characterization of quantum statistical models in quantum estimation theory Interferometric detection of optical phase shifts at the Heisenberg limit Nuisance parameter problem in quantum estimation theory: Tradeoff relation and qubit examples Download references This work was supported by the Australian Research Council (ARC) under the Centre of Excellence for Quantum Computation and Communication Technology (Grant No was supported by the UEC Research Support Program The authors are grateful to Professor Nagaoka and Professor Hayashi for helpful discussions Centre for Quantum Computation and Communication Technology School of Physical and Mathematical Sciences Graduate School of Informatics and Engineering and worked out the optimal POVMs in the examples All authors contributed to discussions regarding the results in this paper Download citation DOI: https://doi.org/10.1038/s41534-021-00414-1 As part of an Inter-University Exchange Project the "DX Manufacturing Workshops 2024"--organized by students from both NUT and the Indian Institute of Technology Madras (IITM)--was held on December 18 (Wednesday) at Miraie Nagaoka in a hybrid format comprising both on-site and online participation The chairpersons and presenters of this workshop Tomohiro Hayashi from the Institute of Science Tokyo a large number of academic staff and students from our partner universities in India and Vietnam also participated online Researchers gave presentations on "Design of Bioinert Surfaces by Informatics and Robotics" and "Cold Spraying Technology for Additive Manufacturing" there was a poster session in which participating students presented their research to one another This was followed by a group discussion on "DX for Industry" and "DX for 3D Bio-surface Design" in which the participants engaged in lively Q&A and debates which provided an at-home space where participants could freely exchange their opinions and engage in meaningful dialogue NUT will continue to provide opportunities for research presentations and discussions through such workshops and to promote initiatives under this Inter-University Exchange Project NUT will work to further expand our joint research and student exchanges with India Copyright© Nagaoka University of Technology Share your travel photos with us by hashtagging your images with #visitjapanjp Access: 30 min walk from JR Nagaoka Station on the JR Shinetsu Main Line For information regarding special transit passes servicing the area https://www.jreast.co.jp/multi/pass/eastpass_t.html　 Browse the JNTO site in one of multiple languages Niigata — Wednesday marked the 20th anniversary of the Niigata Prefecture Chuetsu Earthquake that claimed 68 lives please disable the ad blocking feature and reload the page This website uses cookies to collect information about your visit for purposes such as showing you personalized ads and content By clicking “Accept all,” you will allow the use of these cookies Users accessing this site from EEA countries and UK are unable to view this site without your consent People offered flowers at Myoken Memorial Park in Nagaoka near the site where a woman and her two children were buried alive in a landslide “It’s a painful memory that we must not forget,” said a 53-year-old Sapporo civil servant who had helped with the restoration of the local sewage system the year after the quake The quake marked the highest level on the Japanese seismic intensity scale of seven “I am in charge of disaster prevention work now and I want to keep this disaster in mind.” Our weekly ePaper presents the most noteworthy recent topics in an exciting © 2025 The Japan News - by The Yomiuri Shimbun Commissioned by British Journal of Photography in partnership with Visit California the resulting bodies of work shed light on the lesser-known sides of the state “There is a decent Japanese community in Paraguay,” he says “but I was the minority and I could feel it.” Nagaoka is third-generation Japanese “You get to a point when you begin to hide your Asianness; you are almost forced to assimilate to the dominant culture.” Nagaoka would adopt certain “survival tactics” Often he would find himself subconsciously assimilating to whichever culture was dominant; on other occasions he would embrace Asian stereotypes “It was all I had to grasp onto,” he says of the latter “There was not anything else so you start to accept that being Asian begin to define you.” With a lack of Asian American role models both within his community and popular culture throughout his childhood Nagaoka’s identity was in constant flux Gold Mountain seeks to provide “an honest and genuine representation” of Asian Americans living in California something Nagaoka says is currently lacking speaking of his interest in photographing Asian Americans living in the state Subcultures have grown and flourished out of that.” The opportunities afforded by California’s large and diverse Asian American population are undoubtedly a draw for those not originally from the state moved to Los Angeles from Georgia at the beginning of 2018 the Vietnamese community is generally very conservative; being queer I didn’t identify with that,” she says “My mum has told me about her life in California so I moved here to get closer to that community and to also connect with other queer Asians.” Binh is a member of Unity a California-based skate group that arranges meet-ups for queer people living in the state It was through its Instagram pages that she began to connect with other LA-based Asian Americans “In high school [where she grew up in Pennsylvania] my friends were mostly white – I didn’t have any Asian friends,” she says “I guess because I was born in the US and only had American friends I didn’t feel Asian American I was always hanging around American people so I saw them As you grow older and you start making your own decisions you begin to realise things I never thought about it until I finished high school When I was living on my own – making my own work and own decisions – I suddenly realised that there was a lot I didn’t know about myself.” Gold Mountain is a project of great personal importance for Nagaoka His approach was therefore naturally inquisitive “I am asking lots of questions about what it means to be Asian American,” he says “I have met people that are ashamed to be Asian – is this an effect of not seeing ourselves in positions of power I am a photographer and yet I don’t see images of Asians – does that have an effect on someone growing up I don’t have the answers to these questions and that is why I started this project.” For many of the subjects that Nagaoka photographed the lack of Asian role models in US popular culture had a significant effect on their identity as a child and young adult moved to Los Angeles with his childhood friend John just several months ago “At school you get told that you are the Asian kid so you kind of accept that you are the Asian kid,” he says “You begin to make all the stereotypes and jokes part of your identity but We all go through that stage of not truly identifying as Asian because it somehow this is not mirrored in the media he engages with “Unless it is anime or a foreign film coming to America Asians are never depicted in mainstream media,” he says carried out by a group of California-based scholars found that 155 of the 242 programmes studied did not have AAPI (Asian Americans and Pacific Islanders) series regulars The researchers reached an overall conclusion that although the last 10 years have seen an increase in the opportunities for AAPI actors in US television their characters “remain marginalised and tokenised.” Tracy spoke at length about the lack of Asian representation in mainstream media “I always geek out when I see Asian Americans “I definitely see a lack of representation – I can’t really name any films right now that have Asian leads.” It is not solely the lack of media representation that for many Asian Americans prompts questions about their identity Through Nagoaka’s various conversations with his subjects it becomes clear that upbringing also has a part to play third and fourth-generation Asian Americans because they grew up experiencing “a middle ground” between their heritage and American upbringing “You have this Asian heritage – your parents or grandparents grew up in Asia – and yet you were born and raised in the US,” says Nagoaka “A lot of people have never been to their home country and if they have they feel like a foreigner because the US has become their home.” “The stories I grew up with were told by the people who experienced them,” she says “Not everyone can connect with their heritage on such an intimate level.” She still however struggled with her identity growing up “When my parents came to the US their main priority was me being able to achieve the American Dream That led to them thinking I had to sacrifice a lot of things from my culture “They were so concerned about me not being able to excel at English and being singled out at school for not being American enough Because of that they only allowed me to learn English Binh is beginning to explore and reconnect with her heritage Many of Nagaoka’s most striking shots are taken outside. If there is even a glimmer of sunlight or shadow, Nagaoka finds a way for it to fall curiously upon his subject. Yet it is telling of the photographer’s approach that the majority of his time in California is spent perched on sofas in darkened rooms He had no intention of taking photographs here but these were the spaces where his subjects felt most comfortable speaking candidly and sharing their personal experiences These conversations were intimate and unhurried; in Nagaoka’s mind they bear an equal importance to the photographs he took Gold Mountain is the beginning of an ongoing project While the physical outcome is a series of intimate portraits Nagoaka’s eventual goal is far greater “I know that each Asian culture has its unique power and intricacies but I am interested in seeing if there is something that can unify us all,” he says “Is there something that can rally Asian Americans and bring us together so more people can feel proud to be Asian?” It is an ambition that the individuals Nagoaka photographed in California welcome “Hopefully your project will make people realise the bigger picture and what it means to have Asian representation,” say Binh “I do understand when people question why we need Hollywood to validate us While we criticise Hollywood for not representing us we also need to validate ourselves You are making space for us; you are literally representing us right now we need to validate ourselves if the people in power do not.” Nagoaka remains optimistic: “Change can happen,” he says it is especially important for those who grew up being the token Asian kid I want those people to wake up in the morning and think: ‘I have people to look up to President Kamado was interviewed by Worldfolio on April 9 2024 regarding to the engineering education and international exchange and programs of our university and this interview was published on Newsweek International Magazine on June 28 PDF version of articles published on Newsweek International Magazine are available as follows To read the article on Newsweek Digital, please click the following URL.https://www.newsweek.com/insights/leading-destination-engineers-nagaoka-university To read the article on the edition on Newsweek Digital https://www.newsweek.com/insights/unlocking-japans-university-potential-amidst-transformative-change （PDF：4,718KB） By Deborah Fleck they share a partnership that has been going strong for 30 years The cities are siblings in the Fort Worth Sister Cities program A delegation from Nagaoka came to Texas last week to celebrate the anniversary the group visited with Fort Worth City Council members and Mayor Betsy Price toured Sundance Square and the Cultural District attended the Japanese Fall Festival in the Fort Worth Botanic Garden and took part in an panel discussion on education at the Botanical Research Institute of Texas They also attended a celebration dinner held in Isoda's honor Saturday at Billy Bob's Texas The dinner included tickets to the Trace Adkins concert A delegation from Fort Worth plans to visit Nagaoka in 2018 to continue the celebrations. For more information about the trip, call 817-632-7106 or email danielle@fwsistercities.org Breaking NewsGet the latest breaking news from North Texas and beyond GoogleFacebookBy signing up you agree to our Terms of Service and Privacy Policy The Greater Dallas Asian-American Chamber of Commerce held its annual awards luncheon Friday at the Dallas Marriott hotel in Addison He touted the state as the "premier land of opportunity." The chamber presented him with a Swarovski crystal rooster commemorating the year of rooster and the governor's birth in the year of the rooster Among awards handed out were eight given to corporate executives for promoting diversity; the Crow Collection Award for Arts and Culture Nada Shabout of the University of North Texas; a Global Arts Award presented to artist Shafaq Ahmad (who has an exhibit at the Irving Arts Center); a Chamber Arts and Culture Award given to the Irving Symphony Orchestra; and Community Service Awards that went to Jack Godhwani and Quynh Chau Stone Chamber president Galileo Jumaoas was host To learn more about the chamber, visit gdaacc.com Asian Mint founder and chef Nikky Phinyawatana was among several women honored at the Women That Soar Awards ceremony Oct She received the Business Award for not only her successful restaurants (she just opened a third Asian Mint on Lovers Lane) but for her philanthropic work Phinyawatana often uses her restaurants to raise money for nonprofits she hosted a fashion show to benefit Genesis Women's Shelter and she recently held a dinner to honor Ron Hall whose story is told in the new movie Same Kind of Different as Me Up next for the chef is her presentation of food from Thailand and Texas at the James Beard House in New York City on Nov To learn more about Phinyawatana, visit asianmint.com The U.S.-India Chamber of Commerce will host its annual awards banquet at 7 p.m. with a reception at 5:30 p.m. at the Westin Dallas Park Central hotel, 12720 Merit Drive in Dallas. To register, visit conta.cc/2gPaGk5 BAPS Charities will host a free health fair from 8:30 a.m. to 12:30 p.m. at BAPS Mandir, 4601 N. State Highway 161 in Irving. Learn more at bapscharities.org/usa/dallas/hf17dallas The DFW Indian Cultural Society's 12th annual Diwali Mela celebration will be from 4 p.m. to midnight at the Cotton Bowl in Fair Park. Find details at dfwdiwalimela.com Against the Grain Productions will host its 2017 Fashion for a Passion fundraiser at 7:30 p.m. at 6500 Cedar Springs Road in Dallas. Find more information at againstthegrainproductions.com. Niigata Prefecture--Partygoers and others wanting a raucous atmosphere should look elsewhere than the newly opened Nobi by Suzuki Coffee here Sound or even a spoken word is not a requisite at the cafe opened the establishment in the Sanwa 3-chome district of Nagaoka His goal is for people with or without a hearing impairment to feel at home there The cafe has been bustling with numerous customers and is alive with their sign language conversations and smiles The name Nobi by Suzuki Coffee embodies its aim to serve as a “third place,” or somewhere other than the home and the workplace which allows customers to feel relaxed (“nobi-nobi” in Japanese) Kuramata graduated from Prefectural Nagaoka School for the Deaf in the city Following a stint working in a semiconductor plant Kuramata became an instructor at his alma mater’s boarding house where he taught his juniors how to live properly in society often suffered hardships at their workplaces Surrounded by colleagues without a hearing impairment with whom they found it difficult to communicate they could not join their conversations even when the latter appeared to be chatting merrily during breaks Many of the graduates thus deepened their sense of solitude Kuramata himself has gone through various experiences he went to a restaurant where workers called customers by their ticket numbers when the dishes were ready Kuramata had to stand near the restaurant counter so he could see when his order was ready Kuramata could not make out what others were saying because everyone wore a mask and he could not read their lips Kuramata found it difficult to live in a society where being able to hear was taken for granted “Couldn’t I do something to help hearing-impaired people live more happily?” he thought at the time That idea led him to leave his job as an instructor two years ago and take a seminar that provided assistance to would-be entrepreneurs and he had made the rounds of cafes across Japan He had come across many cafes where he felt he could open up at once to staff workers and to fellow customers through gestures and by writing even when he was meeting them for the first time He now knew more clearly what he wanted to do He wanted to open a cafe that would allow people both with and without normal hearing to communicate in a relaxed manner Kuramata went to event venues across Niigata Prefecture to set up and operate pop-up cafes there But he came to believe that he would have to study under a professional if he were ever to open a business in earnest with a brick-and-mortar shop Kuramata thereupon contacted Suzuki Coffee Co. a cafe chain operator based in Niigata’s Chuo Ward which offered a tutorial course on know-how for opening a cafe Sato said he was impressed by Kuramata’s enthusiasm to create a place where hearing-impaired people could feel at ease He said he decided the very day that he saw Kuramata to extend assistance for him Sato had part of Suzuki Coffee’s Nagaoka branch office refurbished into a cafe Kuramata usually manages the place all by himself on his own Hearing-impaired people account for about half of the visitors whereas those who are interested in sign language and those who didn’t know about the establishment previously account for the remaining half of the visitors Kuramata takes orders by having his customers point to items on the menu at a counter close to the entrance Some customers look bewildered as they come close to the counter without being greeted and appear ready to leave Kuramata said he will smile at similar visitors and beckon to them “Nothing gets started with people unless you communicate with them,” he said Kuramata said a customer who recently came to his place alone to have a coffee talked about a hearing-impaired subordinate The customer asked Kuramata for advice to understand the subordinate better “What difficulties does a person hard of hearing typically face?” Kuramata quoted the customer as asking him He said he felt happy that the customer had this desire to learn about a disability tutorial sessions on sign language at his cafe once the business gets on track “I want my cafe to be a place where everyone can feel relaxed whether they have normal hearing or not,” Kuramata said “That’s why I call this place a ‘cafe where sound or voice is not a requisite’ instead of an establishment for hearing-impaired people alone I hope that my place will help spread understanding so life will be easier for both groups of people.” Korean cafe hires robot barista to help with social distancing Nagoya’s social breakfast coffee culture creamed by pandemic Carlson has the potential to impact UIC in the 200 free where last season’s top times were held by graduate students Bexon Harrison recently focused full time on swimming after doing that and water polo for much of his high school career Breaststroke specialist Landry Liston has announced her commitment to continue both her academic and athletic careers at George Mason University Lennox is a six-time 4A CHSAA State Champion Texas sophomore Brayden Taivassalo has announced that he is transferring to Arizona State University for the next season Fitter and Faster Swim Camps is the proud sponsor of SwimSwam’s College Recruiting Channel and all commitment news swimming in college is a lifelong dream that is pursued with dedication and determination Fitter and Faster is proud to honor these athletes and those who supported them on their journey Stanford has secured a pair of international commitments on the men’s side for the Cardinal’s class of 2028 Japan’s Go Nagaoka and New Zealand’s Finn Harland will both join Stanford’s squad under fifth-year head coach Dan Schemmel beginning next fall A post shared by Go Nagaoka 長岡豪 (@nagaokag) Nagaoka’s best converted 100 breast time is a few seconds away from NCAA scoring territory while his best 200 converted 200 breast time is about six seconds shy Nagaoka’s Best Converted SCY Times (From SCM)  Harland is a backstroke and freestyle specialist who is slated to represent New Zealand at the World Junior Championships two weeks from now in Israel His best converted 100 back and 100 free times are about five seconds away from NCAA scoring territory Harland’s Best Converted SCY Times (From SCM)  Nagaoka and Harland join Li and Abram Meuller in Stanford’s anticipated graduating class of 2028 The Cardinal men placed 8th at the 2023 NCAA Championships last season with 143.5 points By the time they arrive at Stanford next fall the Pac-12 may no longer exist after eight schools left the conference this summer If you have a commitment to report, please send an email with a photo (landscape, or horizontal, looks best) and a quote to [email protected] Fitter & Faster Swim Camps feature the most innovative teaching platforms for competitive swimmers of all levels. Camps are produced year-round throughout the USA and Canada. All camps are led by elite swimmers and coaches. Visit fitterandfaster.com to find or request a swim camp near you Δdocument.getElementById( "ak_js_1" ).setAttribute( "value" Δdocument.getElementById( "ak_js_2" ).setAttribute( "value" it’s been a pleasure to watch him develop in the last few years in NZ Mary’s International school pumps out yet another Power 5 swimmer Notorious Winterfell Yeti crusher Caskey reeling them in Nagaoka’s opening split for 1:03 is surely faster than 35.98 Which would also mean his closing 50 of that 1.03 is quicker than 35.98 too Was probably 14 or 15 the last time he swam a 50 breast Swimswam been using that cover picture for years They can’t use a recent one or the Stanford team would be seated and crying based on their results in the last couple years They have to go way back to see the men excited At least those men are leaving with Stanford degrees… Just a tad bit better than that ASU degree It is pre-Dan Schemmel because Ted Knapp is in the photo Does swimswam just refuse to use common sense backstroke… 51 free is like 44 low 43 high Agree even if you just use the straight up distance conversion the 100 and 200 breastrokes would be faster not accounting at all for the extra 19 yards you are swimming in a 200 and less wall and underwater as a percentage They’re converting SCM to SCY which is likely translates more accurately than long course His LCM times are a lot better than his SCM times though It does translate better if he’s actually swimming SCM seriously When your LC 100 FR is faster than the SCM version it’s not worth using the SCM time for a conversion Even the very worst swimmers with turns and underwaters still don’t get slower in SC compared to LC times Harland’s best LCM times are from 2023 and SCM from 2021… Pretty sure 2 years makes a big difference for a high schooler There are only about 5 LCM pools available for competition in the whole country and they are usually set up for SCM …Good luck to Finn – great lad and awesome family that’s fair but I’m just reading off the dates of his PRs from swimrankings Been offering my stroke specific formula for a while now and they still won’t bite More from Riley OverendSee All Subscribe to our newsletter and receive our latest updates and training on the milestones that matter most for college success She is the lead author of Foundations for Young Adult Success: A Developmental Framework which draws on research and practice evidence to build a coherent framework of the foundational factors for young adult success and investigates their development from early childhood through young adulthood and how they can be supported through developmental experiences and relationships Six-Year Bachelor’s Degree Completion Rates Understanding CPS Graduates’ Paths Through College Immediate Enrollment and Retention of CPS Graduates in Fall 2020 ©2023 The University of Chicago UChicago Consortium on School Research   Sign up for our email list   Accessibility Niigata JAPAN -- Yonex began construction of a new research and development facility an expansion to the existing Nagaoka development and manufacturing site The facility is aimed at strengthening the analysis of the variety of ways people play sports in a more accurate and timely manner Alongside the innovation center will be an additional manufacturing site to increase the capacity of Japan-made tennis racquets The planning of the Yonex Performance Innovation Center began with an overall emphasis to better understand every player’s needs when playing sports Performance in sport is constantly evolving not only at the professional level but at all levels of participation especially after people’s evolving relationship with sports since the onset of the COVID-19 pandemic the general customer in the sporting goods market place is becoming more fluent in product performance and benefits allowing for more informed product selection that fit each of their playstyles.  In order to introduce performance-driven innovations for different player levels and types a richer analysis of diverse playstyles is necessary the innovation center will be equipped with state-of-the-art analysis equipment to measure players’ movements in conjunction with numerous tennis courts that simulate Grand Slam court conditions*2 and other training facilities that reproduce performance conditions of the sports This center will also be built to act as a training base for athletes By building the innovation center next to the expanding manufacturing site allows for quicker implementation of prototypes to consumer products The additional manufacturing site will begin construction in November 2023 a site primarily focused on tennis racquets Yonex tennis racquets have been highly regarded by top players for their performance where at the 2023 Australian Open Yonex was the second most-used racquet and string brand amongst participants*3 Alongside higher rates of adoption by professionals the Yonex brand is gaining popularity among tennis fans seeing an increase in brand presence in North America Yonex is committed to providing innovation-driven high quality products to everyday athletes and world-class athletes alike will strive to improve and increase the products that will support their game *3 Racquet usage rate of Australian Open finalists Name:              Yonex Performance Innovation Center (Tentative Name) Location:           Nakayama Floor Area:        8,730㎡ Completion of Construction:           June 2024　(Scheduled) Name:              Yonex Niigata Factory Floor Area:        12,000㎡ Start of Construction:                     November 2023　(Scheduled) Completion of Construction:           June 2025　(Scheduled) Contact Us I’ve been using the Nagaoka MP-110 / Rega P3 combo running right into my 1970s-era Sansui AU-555A integrated amplifier’s Phono input for the past about-a-year This combo played my greatly-loved yet minuscule record collection (it’s really not even a collection it’s more of a sample) wonderfully — or as Don Fanucci said in Godfather Part II Some of the things I want from any cartridge In preparation for the birth of TM Chapter 3, I’ve begun assembling a new system Part of that system is the Parasound Zphono Phono Preamp (more on that soon) and I can say that the mighty yellow wonder that is the Nagaoka MP-110 I want to buy more records (again) [footnote 1] You can buy the Nagaoka MP-110 MM Cartridge for $134.93 on Amazon (as of today) and perhaps even less if you search around I’ve begun buying records (and books) again The Voice Made Visible: Margaret Watts Hughes and Her Eidophone We are using cookies to give you the best experience on our website You can find out more about which cookies we are using or switch them off in settings This website uses cookies so that we can provide you with the best user experience possible Cookie information is stored in your browser and performs functions such as recognizing you when you return to our website while also helping us understand which sections of the website you find most interesting and useful Strictly Necessary Cookies should be enabled at all times so that we can save your preferences for cookie settings we will not be able to save your preferences This means that every time you visit this website you will need to enable or disable cookies again This website uses Google Analytics to collect anonymous information such as the number of visitors to the site Keeping this cookie enabled helps us to improve our website Please enable Strictly Necessary Cookies first so that we can save your preferences We know you are not here for the first time What comes to your mind when you hear the Moravian-Silesian region in the Czech Republic It has been eight months since I came to the Czech Republic, and this is the fourth time that I come to Ostrava. For me, the Moravian-Silesian region is one of the regions that I visit most frequently. In particular, “Japonské dny v Ostravě“　held in October was very impressive It is a magnificent pleasure that such a variety of activities to promote Japanese culture are being carried on a regular basis and are being well received by many people In Karviná an internationally renowned Japanese company “Shimano” that manufactures bicycle gears has been contributing to the local economy over 20 years and their products must be used by many Czech bicycle lovers the Technical University of Ostrava maintains cooperative relationships with several Japanese universities and its history with Japan goes back more than 20 years It is also a pleasant surprise to know that the Governor of the region has been running a KARATE dojo in Havířov for more than 30 years This region indeed has very deep ties with Japan in various fields In which areas do you see potential opportunities for cooperation and collaboration between countries that are more than 9,000 kilometres away from each other as the crow flies Japan and the Czech Republic are strategic partners that share their fundamental values our relations spanning more than 100 years is marked by support and a long tradition of friendship.  Japan has been the second biggest investing countries in the Czech Republic and as many as 280 Japanese companies are successfully operating throughout the country The automobile industry remains an important sector we also see a trend of investments in the field of environmentally friendly products such as heat pumps and recyclable packaging materials These products are produced in line with EU regulations and are highly competitive in the EU market and beyond The world is facing multiple challenges today and the aging of society with fewer children I hope that Japan and the Czech Republic will further deepen their cooperation in solving these global issues What would you like from the point of view of Czech-Japanese relations in the coming years Japan and the Czech Republic have very good relations in the political If you were to draw a diagram of these relations it would look like an equilateral triangle My first task is to further expand and deepen this triangle I also hope to build new pillars of cooperation I would like to strengthen cooperation in the fields of security and science and technology I believe that cooperation in these fields between Japan and the Czech Republic I must mention about an important role to be played by EXPO 2025 in Osaka which will open in the mid-April next year It gives a great opportunity to bring our relationship to a higher level The Osaka-Kansai Expo will welcome 28 million visitors from around the world over a six-month period It is a unique opportunity to showcase the traditional culture and advanced technologies of the Czech Republic not only to Japan It will generate even more tourists and new business opportunities for both Japan the Czech Republic an investment in the future of the Czech economy and I am pleased to note a growing interest in the Expo by many Czech stakeholders kteří překonali složité překážky a vybudovali úspěšné firmy pořádání eventů a natáčení Voices of Industry Copyright © Japan International Cooperation Agency Metrics details We consider an array of four quantum dots defined in phosphorene containing three excess electrons in the conditions of near half filling when itinerant Nagaoka ferromagnetism is expected to appear in a square array with isotropic interdot hopping The interdot hopping in the array arranged in a square inherits the anisotropy from the form of the phosphorene conduction band We apply the configuration interaction method for discussion of the appearance and stability of the spin-polarized ground state and discuss the compensation of the effective mass anisotropy by the geometry of the quantum dot array Our study shows strong stability of Nagaoka ferromagnetism for optimized geometry of the array with the Nagaoka gap as large as ∼ 230 µeV A phase diagram for the ground-state spin ordering versus the geometric parameters of the array is presented We study the suppression of the ferromagnetism in a transition of the \(2\times 2\) array to a quasi-1D chain and indicate that the shift of one of the quantum dots away from the array center is enough to transform the system to a quantum dot chain A shift in the zigzag crystal direction induces the low-spin ground state more effectively than a shift along the armchair direction We also discuss the robustness of the spin ordering against detuning one of the dots The ferromagnetic ground-state survives as long as the detuning is not large enough to trap one of the electrons within a single quantum dot (for positive detuning) or remove one of the quantum dots of the accessible energy range (for negative detuning) The experimental realization of such systems still requires that the energy gap be at least a few \(\mu\)eV and its tolerance to disorder and imperfections the effective mass of the electrons in phosphorene is much higher than that of GaAs The large effective electron mass reduces the contribution of kinetic energy and then the physics is largely affected by electron–electron interactions which makes quantum dots in phosphorene an appealing choice for studies of the interaction-driven Nagaoka ferromagnetism (a) Crystal structure of monolayer phosphorene indicating the zigzag direction (y-axis) and the armchair direction (x-axis) We expect our system to have a much larger gap for the strongest ferromagnetic state The magnetic field produces splitting between states of the z component of the total spin \(\sigma _z=-3/2\) and \(\sigma _z=-1/2\) of about 0.22 \(\mu\)eV this energy will be small compared to the largest Nagaoka gap and will affect the ground state only when the Nagaoka gap is of the same order (near the phase transition) and not the results near the point of largest gap The energy gap is calculated as \(\Delta E =E_{3/2}-E_{1/2}\) where \(E_{3/2}\) is the energy of the spin quantum number \(S=3/2\) state and \(E_{1/2}\) We use a square mesh with spacing \(\Delta x\) in both directions so that the action of Hamiltonian on the wave-function \(\Psi _{\alpha ,\beta }=\Psi (x_\alpha Inside the computational square box of side length 50 nm the model quantum dots are arranged in a rectangle with distance between the centers of dots \(2\mu _x\) in the armchair direction (x) and \(2\mu _y\) in the zigzag crystal direction (y) The spacings influence both the interdot tunneling rates (hopping energy) and the interdot electron–electron interaction The applied model confinement potential is The energy spectrum for three interacting electrons in our system is calculated in a continuum approach using the following Hamiltonian We investigate the electron distribution in the dots by extracting the electron density from the three electron wave-functions \(\Psi\), where \(\Psi\) is the three-electron ground-state wave function. The potential (left column) and the square root of electron density (right column) with parameters the magnetic field is 1 mT and the potential depth \(V_d=125\) meV The color scale for each plot is to the right of each plot h) indicate the potential and square root of the density for the configuration of dots with the largest Nagaoka gap The energy spectrum as a function of magnetic field B for parameter sets of \(\mu _x=9\) nm (a) Potential depth is set \(V_d=125\) meV for all the chosen sets in (a–d) The colour of each line denotes the spin eigenvalue of the energy state and the scale is shown to right of each plot The spectra show the shifting of ground states and the changing Nagaoka gap as the configurations of the dots change Subfigure (d) shows the spectrum for the configuration with the largest Nagaoka gap Although the tunneling coupling between the dots is weak it is already large enough to promote the spin-polarized quadruplet with the total spin eigenvalue of \(S=3/2\) and the z component eigenvalues \(\sigma _z=-3/2,-1/2,1/2,3/2\) in the ground state An asymptotic case of large interdot distances corresponds to tunneling and interaction being negligible so that the quadruplet becomes degenerate with the spin \(S=1/2\) doublet Reducing the spacing between the dots to \(\mu _x = 8\) nm and \(\mu _y = 6\) nm, the energy gap between the lowest spin \(S=1/2\) and spin \(S=3/2\) states becomes \(100\,\mu\)eV with the high-spin ground state [see Fig. 3b] the top-bottom pair of dots will contain two electrons of opposite spins resulting in the ground state being a spin \(S=1/2\) state due to the spin of the solitary electron The ground state becomes spin-polarized by the Zeeman interaction only at a high magnetic field of about 1.9 T \(\Delta E\) as a function of the parameters \(\mu _y\) and \((\mu _x-\mu _y)\) with potential depth The energy gap is calculated for every point at the center of the hexagons The green and grey regions in the diagram indicate the configurations for which the ground state is a low-spin state The red and yellow regions show the configurations with a spin polarized ground state The largest energy gap \(\Delta E=-230\,\mu\)eV occurs at \(\mu _y=5.2\) nm and \(\mu _x-\mu _y=1.6\) nm and is indicated with the most saturated red color (a) The Nagaoka gap as a function of the parameters \(\mu _y\) for different values of \((\mu _x-\mu _y)\) (b) as a function of parameter \(\mu _x\) for various \(\mu _y\)’s The lines shift towards the negative sides as the system parameters approach the largest Nagaoka gap point after which the lines in both subfigures approach zero To understand in detail the effects of the interactions depending on the location of the dots, we study the cross sections of the phase diagram to see the energy gap as a function of the parameter \(\mu _y\) for various \((\mu _x-\mu _y)\) in Fig. 5a The top-most (bluest) line shows the change in the energy gap \(\Delta E\) with \(\mu _y\) for \(\mu _x-\mu _y=1\) nm indicating a very weak Nagaoka ferromagnetic phase near \(\mu _y=6\) nm As the difference \(\mu _x-\mu _y\) increases the next four lines from the top slowly start to go much lower than the zero line indicating that the system is in a stronger ferromagnetic phase and that it would take more energy to invert one of the spins and break the phase The lowest line is the one that goes the lowest under the zero line which is for the difference \(\mu _x-\mu _y=1.6\) nm The second line from the bottom (greenest) is for the difference of 1.9 nm and is now higher than the difference of 1.6 nm the electron density begins to take the shape of two dumbbells with decreasing x-direction overlap The energy gap, \(\Delta E\) as a function of the parameters \(\mu _y\) and \((\mu _x-\mu _y)\) with potential depth, \(V_d=60\) meV. The energy gap is calculated for every point at the center of the hexagons. The largest energy gap \(\Delta E=-211\,\mu\)eV occurs at \(\mu _y=5.35\) nm and \(\mu _x-\mu _y=2.21\) nm. The diagram is similar as Fig. 4 but the lower potential depth has resulted in a major shift of the largest Nagaoka gap up on the \(\mu _x-\mu _y\) scale and a minor shift on \(\mu _y\) scale the anisotropy of the curve is inherent and is not unique to phosphorene The most evident feature of the plot in Fig. 8 is the asymmetry in the energy gap variation for negative and positive potential changes for the positive change dV the Nagaoka ferromagnetic transitions to the low-spin state at \(dV \approx 7.0\) meV while the same transition occurs at a bit smaller change of \(dV \approx -5.4\) meV for the negative change The transition to the low-spin ground state for positive detuning is due to the localization of an electron in the detuned dot and the transition for negative detuning is due to the delocalization of an electron from the detuned dot which is excluded from the array by the energy mismatch leaving the three dots with an exact half-filling When the top right dot is made deeper [insets (c) and (d)] the electron occupancy of this dot becomes larger than 1 When the dot is made shallower [insets (a) and (b)] the dot is emptied In both cases the conditions for observation of the itinerant ferromagnetism are lifted and the ground state acquires the low spin We have investigated the Nagaoka ferromagnetic state in the phosphorene quantum-dot plaquette using an effective mass Hamiltonian nearly half-filled system We determined the geometry of the plaquette for the maximal stability of the spin-polarized ground state For the chosen parameters of the isotropic single-dot Gaussian confinement the largest Nagaoka gap of \(\Delta E=-230\,\mu\)eV occurs for the parameters \(\mu _x=6.8\) nm and \(\mu _y=5.2\) nm Shifting one of the dots in x or y direction breaks the ferromagnetic ordering of spins stopping the carrier hopping between now nonequivalent locations and forming a quasi-1D chain with low spin ground state on the ground of the Lieb-Mattis theorem Our results indicate that the Nagaoka state in the phosphorene quantum dots exhibits strong resistance to disorder which we tested in the form of detuning one of the dots We showed that the mechanisms breaking the Nagaoka ordering are different for positive and negative detuning and hence the transition occurs for uneven values of detuning The data that support the findings of this study are available from the first author (T.T.) upon reasonable request D-wave pairing near a spin-density-wave instability Indications of \(d_{x}^{2} - y^{2}\) superconductivity in the two dimensional t–J model Ferrimagnetic long-range order of the Hubbard model Quasispin model for itinerant magnetism-effects of short-range order Experimental realization of an extended Fermi–Hubbard model using a 2D lattice of dopant-based quantum dots Phosphorene: An unexplored 2D semiconductor with a high hole mobility Achieving ultrahigh carrier mobility in two-dimensional hole gas of black phosphorus Ambipolar quantum transport in few-layer black phosphorus Integer and fractional quantum hall effect in ultrahigh quality few-layer black phosphorus transistors Negative quasiparticle shifts in phosphorene quantum dots On the influence of dilute charged impurity and perpendicular electric field on the electronic phase of phosphorene: Band gap engineering Bending as a control knob for the electronic and optical properties of phosphorene nanoribbons Systematic competition between strain and electric field stimuli in tuning EELS of phosphorene Insights into the application of 2D phosphorene in dye-sensitized solar cells Anisotropic particle-hole excitations in black phosphorus Electrostatic quantum dot confinement in phosphorene High-mobility transport anisotropy and linear dichroism in few-layer black phosphorus Aharonov–Bohm oscillations in phosphorene quantum rings: Mass anisotropy compensation by confinement potential \(k\cdot p\) theory for phosphorene: Effective g-factors Quantum hall effect in electron-doped black phosphorus field-effect transistors Effective g factor in black phosphorus thin films Quantum Hall effect in black phosphorus two-dimensional electron system Gate tunable quantum oscillations in air-stable and high mobility few-layer phosphorene heterostructures Gauge-invariant grid discretization of the Schrödinger equation Electrostatic quantum dots with designed shape of confinement potential Modeling of electronic properties of electrostatic quantum dots Annular confinement for electrons on liquid helium N-electron ground state energies of a quantum dot in magnetic field Wigner molecules in phosphorene quantum dots Full configuration interaction approach to the few-electron problem in artificial atoms Download references This work was supported by the National Science Centre (NCN) according to decision DEC-2019/35/O/ST3/00097 We gratefully acknowledge Poland’s high-performance computing infrastructure PLGrid (HPC Center Cyfronet) for providing computer facilities and support within computational grant no Research was partly supported by program ”Excellence initiative - research university” for the AGH University of Krakow Faculty of Physics and Applied Computer Science performed the calculations analyzed the results and prepared the manuscript selected and tested the calculation method participated in the discussion of the results and editing the text Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations Download citation DOI: https://doi.org/10.1038/s41598-023-45860-3