4,965 research outputs found

    Tetramethylenedisulfotetramine

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    Tetramethylenedisulfotetramine (CAS 80-12-6), commonly referred to as TETS, was first synthesized in 1933 as a condensation product of sulfamide and formaldehyde. TETS was subsequently used as a rodenticide until banned worldwide in 1991. TETS is, however, still available illegally, primarily in rural China, and is responsible for accidental and intentional poisonings that cause a significant number of human deaths annually. TETS induces convulsive seizures mediated by antagonism of γ-amino-butyric acid (GABA)-mediated chloride channels. There are no known antidotes for TETS poisoning, and in cases of severe TETS intoxication that progress to status epilepticus, prognosis is poor even with aggressive anti-convulsant treatment

    Experiments in the position detection of linear switched reluctance motor

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    Author name used in this publication: S. W. ZhaoAuthor name used in this publication: N. C. CheungAuthor name used in this publication: W. C. GanAuthor name used in this publication: J. M. YangVersion of RecordPublishe

    An automatic disturbance rejection controller for matrix converter

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    Author name used in this publication: Norbert CheungRefereed conference paper2004-2005 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

    Spectrum and Thermodynamics of the one-dimensional supersymmetric t-J model with 1/r21/r^2 exchange and hopping

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    We derive the spectrum and the thermodynamics of the one-dimensional supersymmetric t-J model with long range hopping and spin exchange using a set of maximal-spin eigenstates. This spectrum confirms the recent conjecture that the asymptotic Bethe-ansatz spectrum is exact. By empirical determining the spinon degeneracies of each state, we are able to explicitly construct the free energy.Comment: 13 pages, Latex, (published in PRB46, 6639 (1992)

    Chiral zero-mode for abelian BPS dipoles

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    We present an exact normalisable zero-energy chiral fermion solution for abelian BPS dipoles. For a single dipole, this solution is contained within the high temperature limit of the SU(2) caloron with non-trivial holonomy.Comment: 9 pages, 1 figure (in 2 parts), presented at the workshop on "Confinement, Topology, and other Non-Perturbative Aspects of QCD", 21-27 Jan. 2002, Stara Lesna, Slovaki

    Wilson Loops in N=2 Super-Yang-Mills from Matrix Model

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    We compute the expectation value of the circular Wilson loop in N=2 supersymmetric Yang-Mills theory with N_f=2N hypermultiplets. Our results indicate that the string tension in the dual string theory scales as the logarithm of the 't Hooft coupling.Comment: 37 pages, 9 figures; v2: Numerical factors corrected, simple derivation of Wilson loop and discussion of continuation to complex lambda added; v3: instanton partition function re-analyzed in order to take into account a contribution of the hypermultiplet

    Once more on the Witten index of 3d supersymmetric YM-CS theory

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    The problem of counting the vacuum states in the supersymmetric 3d Yang-Mills-Chern-Simons theory is reconsidered. We resolve the controversy between its original calculation by Witten at large volumes and the calculation based on the evaluation of the effective Lagrangian in the small volume limit. We show that the latter calculation suffers from uncertainties associated with the singularities in the moduli space of classical vacua where the Born-Oppenheimer approximation breaks down. We also show that these singularities can be accurately treated in the Hamiltonian Born-Oppenheimer method, where one has to match carefully the effective wave functions on the Abelian valley and the wave functions of reduced non-Abelian QM theory near the singularities. This gives the same result as original Witten's calculation.Comment: 27 page

    Direct observation of delithiation as the origin of analog memristance in LixNbO2

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    The discovery of analog LixNbO2 memristors revealed a promising new memristive mechanism wherein the diffusion of Li+ rather than O2- ions enables precise control of the resistive states. However, directly correlating lithium concentration with changes to the electronic structure in active layers remains a challenge and is required to truly understand the underlying physics. Chemically delithiated single crystals of LiNbO2 present a model system for correlating lithium variation with spectroscopic signatures from operando soft x-ray spectroscopy studies of device active layers. Using electronic structure modeling of the x-ray spectroscopy of LixNbO2 single crystals, we demonstrate that the intrinsic memristive behavior in LixNbO2 active layers results from field-induced degenerate p-type doping. We show that electrical operation of LixNbO2-based memristors is viable even at marginal Li deficiency and that the analog memristive switching occurs well before the system is fully metallic. This study serves as a benchmark for material synthesis and characterization of future LixNbO2-based memristor devices and suggests that valence change switching is a scalable alternative that circumvents the electroforming typically required for filamentary-based memristors
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