150,873 research outputs found

    Groups Accuse Apple Supplier in China of Labor Violations

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    This document is part of a digital collection provided by the Martin P. Catherwood Library, ILR School, Cornell University, pertaining to the effects of globalization on the workplace worldwide. Special emphasis is placed on labor rights, working conditions, labor market changes, and union organizing.CLW_2014_Report_China_groups_accuse.pdf: 44 downloads, before Oct. 1, 2020

    Ricci flow and the metric completion of the space of Kahler metrics

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    We consider the space of Kahler metrics as a Riemannian submanifold of the space of Riemannian metrics, and study the associated submanifold geometry. In particular, we show that the intrinsic and extrinsic distance functions are equivalent. We also determine the metric completion of the space of Kahler metrics, making contact with recent generalizations of the Calabi-Yau Theorem due to Dinew, Guedj-Zeriahi, and Kolodziej. As an application, we obtain a new analytic stability criterion for the existence of a Kahler-Einstein metric on a Fano manifold in terms of the Ricci flow and the distance function. We also prove that the Kahler-Ricci flow converges as soon as it converges in the metric sense

    Theoretical study of impurity-induced magnetism in FeSe

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    Experimental evidence suggests that FeSe is close to a magnetic instability, and recent scanning tunneling microscopy (STM) measurements on FeSe multilayer films have revealed stripe order locally pinned near defect sites. Motivated by these findings, we perform a theoretical study of locally induced magnetic order near nonmagnetic impurities in a model relevant for FeSe. We find that relatively weak repulsive impurities indeed are capable of generating short-range magnetism, and explain the driving mechanism for the local order by resonant eg-orbital states. In addition, we investigate the importance of orbital-selective self-energy effects relevant for Hund's metals, and show how the structure of the induced magnetization cloud gets modified by orbital selectivity. Finally, we make concrete connection to STM measurements of iron-based superconductors by symmetry arguments of the induced magnetic order, and the basic properties of the Fe Wannier functions relevant for tunneling spectroscopy.Comment: 10 pages, 4 figure

    On universal partial words

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    A universal word for a finite alphabet AA and some integer n1n\geq 1 is a word over AA such that every word in AnA^n appears exactly once as a subword (cyclically or linearly). It is well-known and easy to prove that universal words exist for any AA and nn. In this work we initiate the systematic study of universal partial words. These are words that in addition to the letters from AA may contain an arbitrary number of occurrences of a special `joker' symbol A\Diamond\notin A, which can be substituted by any symbol from AA. For example, u=0011100u=0\Diamond 011100 is a linear partial word for the binary alphabet A={0,1}A=\{0,1\} and for n=3n=3 (e.g., the first three letters of uu yield the subwords 000000 and 010010). We present results on the existence and non-existence of linear and cyclic universal partial words in different situations (depending on the number of \Diamonds and their positions), including various explicit constructions. We also provide numerous examples of universal partial words that we found with the help of a computer

    Effects of Vanadium doping on BaFe2As2

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    We report an investigation of the structural, magnetic and electronic properties of Ba(Fe(1-x)V(x))2As2 using x-ray, transport, magnetic susceptibility and neutron scattering measurements. The vanadium substitutions in Fe sites are possible up to 40\%. Hall effect measurements indicate strong hole-doping effect through V doping, while no superconductivity is observed in all samples down to 2K. The antiferromagnetic and structural transition temperature of BaFe2As2 is gradually suppressed to finite temperature then vanishes at x=0.245 with the emergence of spin glass behavior, suggesting an avoided quantum critical point (QCP). Our results demonstrate that the avoided QCP and spin glass state which were previously reported in the superconducting phase of Co/Ni-doped BaFe2As2 can also be realized in non-superconducting Ba(Fe(1-x)V(x))2As2.Comment: 5 pages, 6 figure

    Intertwined magnetic and nematic orders in semiconducting KFe0.8_{0.8}Ag1.2_{1.2}Te2_2

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    Superconductivity in the iron pnictides emerges from metallic parent compounds exhibiting intertwined stripe-type magnetic order and nematic order, with itinerant electrons suggested to be essential for both. Here we use X-ray and neutron scattering to show that a similar intertwined state is realized in semiconducting KFe0.8_{0.8}Ag1.2_{1.2}Te2_2 (K5_5Fe4_4Ag6_6Te10_{10}) without itinerant electrons. We find Fe atoms in KFe0.8_{0.8}Ag1.2_{1.2}Te2_2 form isolated 2×22\times2 blocks, separated by nonmagnetic Ag atoms. Long-range magnetic order sets in below TN35T_{\rm N}\approx35 K, with magnetic moments within the 2×22\times2 Fe blocks ordering into the stripe-type configuration. A nematic order accompanies the magnetic transition, manifest as a structural distortion that breaks the fourfold rotational symmetry of the lattice. The nematic orders in KFe0.8_{0.8}Ag1.2_{1.2}Te2_2 and iron pnictide parent compounds are similar in magnitude and how they relate to the magnetic order, indicating a common origin. Since KFe0.8_{0.8}Ag1.2_{1.2}Te2_2 is a semiconductor without itinerant electrons, this indicates that local-moment magnetic interactions are integral to its magnetic and nematic orders, and such interactions may play a key role in iron-based superconductivity.Comment: supplemental material available upon request, to be published in PR
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