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Faulty evidence for superconductivity in ac magnetic susceptibility of sulfur hydride under pressure

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National Science Review 2022年第6期9卷 43-44页

作者： j.e.hirsch Department of Physics University of California

Sulfur hydride was reported to become superconducting at high pressure and temperature [1]. Posteriorly, Huang and coworkers measured its ac magnetic susceptibility [2], reportedly confirming that finding. According to Semenok and Oganov [3], their work ‘sets a new standard for experimental studies of superconductivity at high pressure’.Instead I argue here that the ac susceptibility measurements of Huang et al.

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Clear evidence against superconductivity in hydrides under high pressure

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Matter and Radiation at extremes 2022年第5期7卷 55-64页

作者： j.e.hirsch F.Marsiglio Department of Physics University of CaliforniaSan DiegoLa JollaCalifornia 92093-0319USA Department of Physics University of AlbertaEdmontonAlberta T6G 2E1Canada

The Meissner effect,magnetic field expulsion,is a hallmark of *** with it,superconductors exclude applied magnetic ***,Minkov et al.[***.13,3194(2022)]presented experimental results reportedly showing“definitive evidence of the Meissner effect”in sulfur hydride and lanthanum hydride under high pressure,and eremets et al.[***.35,965(2022)]argued that“the arguments against superconductivity(in hydrides)can be either refuted or explained.”Instead,we show here that the evidence presented in those papers does not support the case for superconductivity in these *** with experimental evidence discussed in earlier papers,we argue that this strongly suggests that hydrides under pressure are not high-temperature superconductors.

关键词： hydrides materials. superconductivity

Incompatibility of published ac magnetic susceptibility of a room temperature superconductor with measured raw data

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Matter and Radiation at extremes 2022年第4期7卷 65-80页

作者： j.e.hirsch D.van der Mare Department of Physics University of CaliforniaSan DiegoLa JollaCalifornia 92093-0319USA Department of Quantum Matter Physics University of Geneva24 Quai Ernest-Ansermet1211 GenevaSwitzerland

A material termed“carbonaceous sulfur hydride”has recently been reported to be a high-pressure room temperature superconductor[Snider et al.,Nature 586,373(2020)].We have previously pointed out that certain anomalies observed in the published data for the ac magnetic susceptibility of this material would be cleared up once the measured raw data were made available[***,arXiv:2110.12854v1(2021)and ***,Physica C 590,1353964(2021)(temporarily removed)].The measured raw data,as well as numerical values of the data presented in figures in the aforementioned paper by Snider et al.,have recently been posted on the arXiv[*** and ***,arXiv:2111.15017v1(2021)and *** and ***,arXiv:2111.15017v2(2021)].Here,we report the results of our analysis of these raw data and published data and our conclusion that the raw data are incompatible with the published *** of these results for the claim that the material is a room temperature superconductor are discussed.

关键词： compatibility superconductor removed

Corrigendum to: “Incompatibility of published ac magnetic susceptibility of a room temperature superconductor with measured raw data” [Matter Radiat. extremes 7, 048401 (2022)]

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Matter and Radiation at extremes 2022年第5期7卷 79-79页

作者： j.e.hirsch D.van der Marel Department of Physics University of CaliforniaSan DiegoLa JollaCalifornia 92093-0319USA Department of Quantum Matter Physics University of Geneva24 Quai Ernest-Ansermet1211 GenevaSwitzerland

(1)The caption of Fig.11 erroneously states“(c)Reproduced with permission from Debessai et al.,***.102,197002(2009).Copyright 2009 the American Physical Society.”Instead it should state“(c)Reproduced with permissio... 详细信息

关键词： Rev.B compatibility superconductor

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衡量科学家个人成就的一个量化指标

科学观察 2006年第1期1卷 2-7页

作者： j.e.hirsch 刘俊婉马建华 Department of Physics University of California San Diego La JollaCA 92093-0319

h指数是美国加州大学圣迭哥分校的物理学家***教授在2005年提出的一项旨在评价科学家个人绩效的指标。由于这项指标测量的结果在一定程度上能够解决传统的文献计量学指标在科学家个人绩效评价中的局限性,因此,该指标立即成为一个热点问... 详细信息

h指数是美国加州大学圣迭哥分校的物理学家***教授在2005年提出的一项旨在评价科学家个人绩效的指标。由于这项指标测量的结果在一定程度上能够解决传统的文献计量学指标在科学家个人绩效评价中的局限性,因此,该指标立即成为一个热点问题。一个问题能够引起人们的关注、思考或争论就是一个好的问题,一个值得探讨的问题。经与***教授联系并得到他的授权,《科学观察》特拨出一定的篇幅,将h指数介绍给中国的广大科学家与科技管理工作者。***教授的文章对传统文献计量学指标的优缺点进行了点评,详细论述了h指数的设计思想以及该指标的数学推导。我们推介h指数的出发点是希望国人也能对这样一个热点问题有所思考。中国已经成为文献计量学指标应用的“一片热土”。所幸的是,许多智者已经开始了冷静的反思。任何一个文献计量学指标在适用性上都具有一定的局限性。为了更全面地了解h指数的优点与缺点,我们特别邀请了国内外科学计量学与文献计量学专家对h指数进行评论,其中有四位是普赖斯奖(科学计量学与文献计量学领域最高奖)得主,他们在科研绩效评价的理论研究上有很深的造诣,在科研绩效评价的实际操作中有丰富的经验。希望***教授的文章和特约评论有助于大家对h指数的理解,在操作层面上更好地把握h指数。当你耐心地读完***教授的文章和专家的评论后,你会感到h指数设计者与传统文献计量学指标设计者的思想碰撞和争鸣。或许这就是学术,这就是交流。科学会因此而进步!

关键词：个人绩效科学家文献计量学量化指标科研绩效评价科学计量学 h指数

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Annual variation of adult survival of a south-temperate House Wren population in Argentina

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Avian Research 2024年第2期15卷 229-237页

作者： Gustavo j.Fernandez Mariana e.Carro Paulo e.Llambías Grupo de Investigacion en ecofisiología de Fauna Silvestre INIBIOMA-CONICETAsentamiento Universitario San Martín de los Andes(AUSMA)Universidad Nacional Del ComahuePasaje de la Paz 235(8370)San Martín de los AndesNeuquenArgentina Grupo de Investigacion de Biología de Aves IADIZA CCT-MendozaUniversidad Nacional de CuyoAvenida RuizLeal s/n Parque General San Martin5500MendozaArgentina

Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population *** numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the ***,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival *** found that the probability of adult survival decreased as the abundance of breeding adults *** density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.

关键词： Annual variation CjS Density-dependence Survival Troglodytes aedon bonariae

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Insm1:orchestrating cellular mimicry in the thymus medulla

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Cellular & Molecular Immunology 2024年第4期21卷 414-416页

作者： K.D.james j.e.Cowan UCL Institute of Immunity and Transplantation The Pears BuildingRowland Hill StreetLondonNW32PPUK

The thymus is the primary production site for a functional and self-tolerant T-cell *** establishment of immune tolerance is mediated by the generation and presentation of tissue-restricted self-antigens(TRAs)by medullary thymic epithelial cells(mTeCs),which screen T-cell receptors for self-reactivity to eliminate autoreactive T *** studies have extended our understanding of mTeC heterogeneity by examining the mechanisms by which mTeCs mimic the peripheral self[1].

关键词： medullary eliminate restricted

Impact of device resistances in the performance of graphene‑based terahertz photodetectors

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Frontiers of Optoelectronics 2024年第2期17卷 87-97页

作者： O.Castelló Sofía M.López Baptista K.Watanabe T.Taniguchi e.Diez j.e.Velázquez-Pérez Y.M.Meziani j.M.Caridad j.A.Delgado-Notario Department of Applied Physics University of Salamanca37008 SalamancaSpain Unidad de excelencia en Luz y Materia estructurada(LUMeS) University of Salamanca37008 SalamancaSpain Research Center for electronic and Optical Materials National Institute for Materials Science1-1 NamikiTsukuba 305-0044Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science1-1 NamikiTsukuba 305-0044Japan Nanotechnology Group USAL-NanolabUniversity of Salamanca37008 SalamancaSpain

In recent years,graphene field-effect-transistors(GFeTs)have demonstrated an outstanding potential for terahertz(THz)photodetection due to their fast response and *** features are essential to enable emerging THz applications,including 6G wireless communications,quantum information,bioimaging and ***,the overall performance of these photodetectors may be utterly compromised by the impact of internal resistances presented in the device,so-called access or parasitic *** this work,we provide a detailed study of the influence of internal device resistances in the photoresponse of high-mobility dual-gate GFeT *** dual-gate architectures allow us to fine tune(decrease)the internal resistance of the device by an order of magnitude and consequently demonstrate an improved responsivity and noise-equivalent-power values of the photodetector,*** results can be well understood by a series resistance model,as shown by the excellent agreement found between the experimental data and theoretical *** findings are therefore relevant to understand and improve the overall performance of existing high-mobility graphene photodetectors.

关键词： Graphene THz Photodetector Field-effect transistor Plasmonic

Comparisons of oxbow lake fish assemblages in relation to bigheaded carp establishment in the lower White River, Arkansas

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ecological Processes 2024年第1期13卷 188-205页

作者： Michael A.eggleton Cody j.Salzmann joseph e.Kaiser Shannon C.F.Smith Department of Aquaculture and Fisheries University of Arkansas at Pine Bluff Arkansas Game and Fish Commission Virginia Institute of Marine Science

Background Since the late 1990s, bigheaded carps(largely silver carp [Hypophthalmichthys molitrix] but also bighead carp [H. nobilis]) have established throughout the lower Mississippi River basin. Using previously studied oxbow lakes in the lower White River basin, Arkansas, we compared current(2017, “post-carp” establishment) fish assemblages to historical(2002, “pre-carp” establishment) fish assemblages. Fish assemblages were comprehensively assessed using multiple gears, including boat electrofishing, mini-fyke nets, and experimental small-mesh gill *** T-tests suggested that fish assemblage indices of richness, diversity, evenness, and dominance were often greater(P e post-carp period as reflected by boat electrofishing and experimental gill nets. However, all indices were generally similar(P > 0.05) between the pre-carp and post-carp period with fish assemblages depicted using mini-fyke nets. Nonmetric multidimensional scaling analyses indicated that fish assemblages differed structurally between pre-carp and post-carp periods. Assemblage differences were linked to both small and large abundance changes for more than 20 species. Abundances of gizzard shad(Dorosoma cepedianum), emerald shiner(Notropis atherinoides), pugnose minnow(Opsopoeodus emiliae), crappies(Pomoxis spp.), bluegill(Lepomis macrochirus), orangespotted sunfish(L. humilis), and yellow bass(Morone mississippiensis) declined between the pre-carp and postcarp periods. Conversely, abundances of weed shiner(N. texanus), pallid shiner(Hybopsis amnis), longear sunfish(L. megalotis), buffalofishes(Ictiobus spp.), and gars(Lepisosteus spp.) generally increased during the same *** Although not possible to conclude assemblage shifts were entirely related to bigheaded carps due to the absence of an appropriate reference system where carps did not establish, the wide establishment of these carps is one of the most pervasive changes to have occurred in the lower White

关键词： Bigheaded carp Silver carp Aquatic nuisance species Fish assemblage Oxbow lake Large river