556 research outputs found

    The benefits of being understood: the role of ethnic identity confirmation in knowledge acquisition by expatriates

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    In this article, we propose that the concept of ethnic identity confirmation (EIC), the level of agreement between how expatriates view the importance of their own ethnic identity and how local employees view the importance of expatriates’ ethnic identity, can explain why expatriates who are ethnically similar to host country employees are sometimes less effective than expected when working overseas. Multinationals often choose ethnically similar expatriates for assignments, assuming these expatriates can more effectively acquire knowledge from local employees. Thus, understanding the specific challenges that endanger the realization of this potential is crucial. Our survey, administered to a sample of 128 expatriate-local employee dyads working in China, reveals that both ethnically similar and ethnically different expatriates acquire more local knowledge when EIC is high. However, the association between ethnic (dis)similarity and knowledge acquisition is direct for ethnically different expatriates, whereas for ethnically similar expatriates it is indirect via their perception of local employees’ trustworthiness. We discuss this study’s important implications and provide recommendations for multinationals on how to provide tailored support to expatriates who face different identity challenges

    Particle size segregation in granular flow in silos

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    Segregation and layering of alumina in storage silos are investigated, with a view to predicting output quality versus time, given known variations in input quality on emplacement. A variety of experiments were conducted, existing relevant publications were reviewed, and the basis for an algorithm for predicting the effect of withdrawing from a central flowing region, in combination with variations in quality due to geometric, layering and segregation effects, is described in this report

    Microglia-derived TNFα induces apoptosis in neural precursor cells via transcriptional activation of the Bcl-2 family member Puma

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    Neuroinflammation is a common feature of acute neurological conditions such as stroke and spinal cord injury, as well as neurodegenerative conditions such as Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis. Previous studies have demonstrated that acute neuroinflammation can adversely affect the survival of neural precursor cells (NPCs) and thereby limit the capacity for regeneration and repair. However, the mechanisms by which neuroinflammatory processes induce NPC death remain unclear. Microglia are key mediators of neuroinflammation and when activated to induce a pro-inflammatory state produce a number of factors that could affect NPC survival. Importantly, in the present study we demonstrate that tumor necrosis factor α (TNFα) produced by lipopolysaccharide-activated microglia is necessary and sufficient to trigger apoptosis in mouse NPCs in vitro. Furthermore, we demonstrate that microglia-derived TNFα induces NPC apoptosis via a mitochondrial pathway regulated by the Bcl-2 family protein Bax. BH3-only proteins are known to play a key role in regulating Bax activation and we demonstrate that microglia-derived TNFα induces the expression of the BH3-only family member Puma in NPCs via an NF-jB-dependent mechanism. Specifically, we show that NF-jB is activated in NPCs treated with conditioned media from activated microglia and that Puma induction and NPC apoptosis is blocked by the NF-jB inhibitor BAY-117082. Importantly, we have determined that NPC apoptosis induced by activated microglia-derived TNFα is attenuated in Puma-deficient NPCs, indicating that Puma induction is required for NPC death. Consistent with this, we demonstrate that Puma-deficient NPCs exhibit an B13-fold increase in survival as compared with wild-type NPCs following transplantation into the inflammatory environment of the injured spinal cord in vivo. In summary, we have identified a key signaling pathway that regulates neuroinflammation induced apoptosis in NPCs in vitro and in vivo that could be targeted to promote regeneration and repair in diverse neurological conditions

    SNP Assay Development for Linkage Map Construction, Anchoring Whole-Genome Sequence, and Other Genetic and Genomic Applications in Common Bean.

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    A total of 992,682 single-nucleotide polymorphisms (SNPs) was identified as ideal for Illumina Infinium II BeadChip design after sequencing a diverse set of 17 common bean (Phaseolus vulgaris L) varieties with the aid of next-generation sequencing technology. From these, two BeadChips each with >5000 SNPs were designed. The BARCBean6K_1 BeadChip was selected for the purpose of optimizing polymorphism among market classes and, when possible, SNPs were targeted to sequence scaffolds in the Phaseolus vulgaris 14Ă— genome assembly with sequence lengths >10 kb. The BARCBean6K_2 BeadChip was designed with the objective of anchoring additional scaffolds and to facilitate orientation of large scaffolds. Analysis of 267 F2 plants from a cross of varieties Stampede Ă— Red Hawk with the two BeadChips resulted in linkage maps with a total of 7040 markers including 7015 SNPs. With the linkage map, a total of 432.3 Mb of sequence from 2766 scaffolds was anchored to create the Phaseolus vulgaris v1.0 assembly, which accounted for approximately 89% of the 487 Mb of available sequence scaffolds of the Phaseolus vulgaris v0.9 assembly. A core set of 6000 SNPs (BARCBean6K_3 BeadChip) with high genotyping quality and polymorphism was selected based on the genotyping of 365 dry bean and 134 snap bean accessions with the BARCBean6K_1 and BARCBean6K_2 BeadChips. The BARCBean6K_3 BeadChip is a useful tool for genetics and genomics research and it is widely used by breeders and geneticists in the United States and abroad

    Nonlinear Impurity Modes in Homogeneous and Periodic Media

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    We analyze the existence and stability of nonlinear localized waves described by the Kronig-Penney model with a nonlinear impurity. We study the properties of such waves in a homogeneous medium, and then analyze new effects introduced by periodicity of the medium parameters. In particular, we demonstrate the existence of a novel type of stable nonlinear band-gap localized states, and also reveal an important physical mechanism of the oscillatory wave instabilities associated with the band-gap wave resonances.Comment: 11 pages, 3 figures; To be published in: Proceedings of the NATO Advanced Research Workshop "Nonlinearity and Disorder: Theory and Applications" (Tashkent, 2-6 Oct, 2000) Editors: P.L. Christiansen and F.K. Abdullaev (Kluwer, 2001

    Quantum sticking, scattering and transmission of 4He atoms from superfluid 4He surfaces

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    We develop a microscopic theory of the scattering, transmission, and sticking of 4He atoms impinging on a superfluid 4He slab at near normal incidence, and inelastic neutron scattering from the slab. The theory includes coupling between different modes and allows for inelastic processes. We find a number of essential aspects that must be observed in a physically meaningful and reliable theory of atom transmission and scattering; all are connected with multiparticle scattering, particularly the possibility of energy loss. These processes are (a) the coupling to low-lying (surface) excitations (ripplons/third sound) which is manifested in a finite imaginary part of the self energy, and (b) the reduction of the strength of the excitation in the maxon/roton region

    Stimulated emission of polarization-entangled photons

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    Entangled photon pairs -- discrete light quanta that exhibit non-classical correlations -- play a crucial role in quantum information science (for example in demonstrations of quantum non-locality and quantum cryptography). At the macroscopic optical field level non-classical correlations can also be important, as in the case of squeezed light, entangled light beams and teleportation of continuous quantum variables. Here we use stimulated parametric down-conversion to study entangled states of light that bridge the gap between discrete and macroscopic optical quantum correlations. We demonstrate experimentally the onset of laser-like action for entangled photons. This entanglement structure holds great promise in quantum information science where there is a strong demand for entangled states of increasing complexity.Comment: 5 pages, 4 figures, RevTeX

    Parametric localized modes in quadratic nonlinear photonic structures

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    We analyze two-color spatially localized modes formed by parametrically coupled fundamental and second-harmonic fields excited at quadratic (or chi-2) nonlinear interfaces embedded into a linear layered structure --- a quasi-one-dimensional quadratic nonlinear photonic crystal. For a periodic lattice of nonlinear interfaces, we derive an effective discrete model for the amplitudes of the fundamental and second-harmonic waves at the interfaces (the so-called discrete chi-2 equations), and find, numerically and analytically, the spatially localized solutions --- discrete gap solitons. For a single nonlinear interface in a linear superlattice, we study the properties of two-color localized modes, and describe both similarities and differences with quadratic solitons in homogeneous media.Comment: 9 pages, 8 figure
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