3,599 research outputs found

    Static displacements and chemical correlations in alloys

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    Recent experiments in metallic solid solutions have revealed interesting correlations between static pair-displacements and the ordering behavior of these alloys. This paper discusses a simple theoretical model which successfully explains these observations and which provides a natural framework for analyzing experimental measurements of pair-displacements and chemical correlations in solid solutions. The utility and scope of this model is demonstrated by analyzing results of experiments on Ni−FeNi-Fe and Cr−FeCr-Fe alloys and results of simulations of Cu−AuCu-Au and Cu−AgCu-Ag alloys.Comment: 12 page

    Algebraic K-theory of endomorphism rings

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    We establish formulas for computation of the higher algebraic KK-groups of the endomorphism rings of objects linked by a morphism in an additive category. Let C{\mathcal C} be an additive category, and let Y\ra X be a covariant morphism of objects in C{\mathcal C}. Then Kn(C(X⊕Y))≃Kn(C,Y(X))⊕Kn(C(Y))K_n\big(_{\mathcal C}(X\oplus Y)\big)\simeq K_n\big(_{{\mathcal C},Y}(X)\big)\oplus K_n\big(_{\mathcal C}(Y)\big) for all 1≤n∈N1\le n\in \mathbb{N}, where C,Y(X)_{{\mathcal C},Y}(X) is the quotient ring of the endomorphism ring C(X)_{\mathcal C}(X) of XX modulo the ideal generated by all those endomorphisms of XX which factorize through YY. Moreover, let RR be a ring with identity, and let ee be an idempotent element in RR. If J:=ReRJ:=ReR is homological and RJ_RJ has a finite projective resolution by finitely generated projective RR-modules, then Kn(R)≃Kn(R/J)⊕Kn(eRe)K_n(R)\simeq K_n(R/J)\oplus K_n(eRe) for all n∈Nn\in \mathbb{N}. This reduces calculations of the higher algebraic KK-groups of RR to those of the quotient ring R/JR/J and the corner ring eReeRe, and can be applied to a large variety of rings: Standardly stratified rings, hereditary orders, affine cellular algebras and extended affine Hecke algebras of type A~\tilde{A}.Comment: 21 pages. Representation-theoretic methods are used to study the algebraic K-theory of ring

    Free field realization of the exceptional current superalgebra \hat{D(2,1;\a)}_k

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    The free-field representations of the D(2,1;\a) current superalgebra and the corresponding energy-momentum tensor are constructed. The related screening currents of the first kind are also presented.Comment: Latex file, 10 page

    High-dimensional super-resolution imaging reveals heterogeneity and dynamics of subcellular lipid membranes.

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    Lipid membranes are found in most intracellular organelles, and their heterogeneities play an essential role in regulating the organelles' biochemical functionalities. Here we report a Spectrum and Polarization Optical Tomography (SPOT) technique to study the subcellular lipidomics in live cells. Simply using one dye that universally stains the lipid membranes, SPOT can simultaneously resolve the membrane morphology, polarity, and phase from the three optical-dimensions of intensity, spectrum, and polarization, respectively. These high-throughput optical properties reveal lipid heterogeneities of ten subcellular compartments, at different developmental stages, and even within the same organelle. Furthermore, we obtain real-time monitoring of the multi-organelle interactive activities of cell division and successfully reveal their sophisticated lipid dynamics during the plasma membrane separation, tunneling nanotubules formation, and mitochondrial cristae dissociation. This work suggests research frontiers in correlating single-cell super-resolution lipidomics with multiplexed imaging of organelle interactome

    Dynamics of Ordering in Alloys with Modulated Phases

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    This paper presents a theoretical model for studying the dynamics of ordering in alloys which exhibit modulated phases. The model is different from the standard time-dependent Ginzburg-Landau description of the evolution of a non-conserved order parameter and resembles the Swift-Hohenberg model. The early-stage growth kinetics is analyzed and compared to the Cahn-Hilliard theory of continuous ordering. The effects of non-linearities on the growth kinetics are discussed qualitatively and it is shown that the presence of an underlying elastic lattice introduces qualitatively new effects. A lattice Hamiltonian capable of describing these effects and suitable for carrying out simulations of the growth kinetics is also constructed.Comment: 18 pages, 3 figures (postscript files appended), Brandeis-BC9

    Ethosuximide ameliorates neurodegenerative disease phenotypes by modulating DAF-16/FOXO target gene expression

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    Background Many neurodegenerative diseases are associated with protein misfolding/aggregation. Treatments mitigating the effects of such common pathological processes, rather than disease-specific symptoms, therefore have general therapeutic potential. Results Here we report that the anti-epileptic drug ethosuximide rescues the short lifespan and chemosensory defects exhibited by C. elegans null mutants of dnj-14, the worm orthologue of the DNAJC5 gene mutated in autosomal-dominant adult-onset neuronal ceroid lipofuscinosis. It also ameliorates the locomotion impairment and short lifespan of worms expressing a human Tau mutant that causes frontotemporal dementia. Transcriptomic analysis revealed a highly significant up-regulation of DAF-16/FOXO target genes in response to ethosuximide; and indeed RNAi knockdown of daf-16 abolished the therapeutic effect of ethosuximide in the worm dnj-14 model. Importantly, ethosuximide also increased the expression of classical FOXO target genes and reduced protein aggregation in mammalian neuronal cells. Conclusions We have revealed a conserved neuroprotective mechanism of action of ethosuximide from worms to mammalian neurons. Future experiments in mouse neurodegeneration models will be important to confirm the repurposing potential of this well-established anti-epileptic drug for treatment of human neurodegenerative diseases

    Assessment of Dentally Related Function in Individuals with Cognitive Impairment: The Dental Activities Test

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    To develop and validate the Dental Activities Test (DAT), a clinical tool for measuring dentally-related function in cognitively-impaired older adults

    Determinant representations of scalar products for the open XXZ chain with non-diagonal boundary terms

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    With the help of the F-basis provided by the Drinfeld twist or factorizing F-matrix for the open XXZ spin chain with non-diagonal boundary terms, we obtain the determinant representations of the scalar products of Bethe states of the model.Comment: Latex file, 28 pages, based on the talk given by W. -L. Yang at Statphys 24, Cairns, Australia, 19-23 July, 201
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