69 research outputs found

    Inelastic neutron and x-ray scattering as probes of the sign structure of the Fe-pnictide superconducting gap

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    Neutron spin-flip scattering observations of a resonance in the superconducting state is often taken as evidence of an unconventional superconducting state in which the gap changes sign Ī”(k+Q)=āˆ’Ī”(k)\Delta(k+Q)=-\Delta(k) for momentum transfers QQ which play an important role in the pairing. Recently questions regarding this identification for the Fe-pnictide superconductors have been raised and it has been suggested that Ī”(k+Q)=Ī”(k)\Delta(k+Q)=\Delta(k). Here we propose that inelastic neutron or x-ray scattering measurements of the spectral weight of a phonon of momentum QQ can distinguish between these two pairing scenarios.Comment: 4 pages, 4 figure

    Natural Diagonal Riemannian Almost Product and Para-Hermitian Cotangent Bundles

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    We obtain the natural diagonal almost product and locally product structures on the total space of the cotangent bundle of a Riemannian manifold. We find the Riemannian almost product (locally product) and the (almost) para-Hermitian cotangent bundles of natural diagonal lift type. We prove the characterization theorem for the natural diagonal (almost) para-K\"ahlerian structures on the total spaces of the cotangent bundle.Comment: 10 pages, will appear in Czechoslovak Mathematical Journa

    Cohesin is required for higher-order chromatin conformation at the imprinted IGF2-H19 locus

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    Cohesin is a chromatin-associated protein complex that mediates sister chromatid cohesion by connecting replicated DNA molecules. Cohesin also has important roles in gene regulation, but the mechanistic basis of this function is poorly understood. In mammalian genomes, cohesin co-localizes with CCCTC binding factor (CTCF), a zinc finger protein implicated in multiple gene regulatory events. At the imprinted IGF2-H19 locus, CTCF plays an important role in organizing allele-specific higher-order chromatin conformation and functions as an enhancer blocking transcriptional insulator. Here we have used chromosome conformation capture (3C) assays and RNAi-mediated depletion of cohesin to address whether cohesin affects higher order chromatin conformation at the IGF2-H19 locus in human cells. Our data show that cohesin has a critical role in maintaining CTCF-mediated chromatin conformation at the locus and that disruption of this conformation coincides with changes in IGF2 expression. We show that the cohesin-dependent, higher-order chromatin conformation of the locus exists in both G1 and G2 phases of the cell cycle and is therefore independent of cohesin's function in sister chromatid cohesion. We propose that cohesin can mediate interactions between DNA molecules in cis to insulate genes through the formation of chromatin loops, analogous to the cohesin mediated interaction with sister chromatids in trans to establish cohesion

    Multiple Organ System Defects and Transcriptional Dysregulation in the Nipbl+/āˆ’ Mouse, a Model of Cornelia de Lange Syndrome

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    Cornelia de Lange Syndrome (CdLS) is a multi-organ system birth defects disorder linked, in at least half of cases, to heterozygous mutations in the NIPBL gene. In animals and fungi, orthologs of NIPBL regulate cohesin, a complex of proteins that is essential for chromosome cohesion and is also implicated in DNA repair and transcriptional regulation. Mice heterozygous for a gene-trap mutation in Nipbl were produced and exhibited defects characteristic of CdLS, including small size, craniofacial anomalies, microbrachycephaly, heart defects, hearing abnormalities, delayed bone maturation, reduced body fat, behavioral disturbances, and high mortality (75ā€“80%) during the first weeks of life. These phenotypes arose despite a decrease in Nipbl transcript levels of only āˆ¼30%, implying extreme sensitivity of development to small changes in Nipbl activity. Gene expression profiling demonstrated that Nipbl deficiency leads to modest but significant transcriptional dysregulation of many genes. Expression changes at the protocadherin beta (Pcdhb) locus, as well as at other loci, support the view that NIPBL influences long-range chromosomal regulatory interactions. In addition, evidence is presented that reduced expression of genes involved in adipogenic differentiation may underlie the low amounts of body fat observed both in Nipbl+/āˆ’ mice and in individuals with CdLS

    3D ITO-nanowire networks as transparent electrode for all-terrain substrate

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    A 3D ITO nanowire network with high quality by using polystyrene as an assisted material has been prepared, demonstrating superior optoelectronic performances with a sheet resistance of 193ā€‰Ī©/sq at 96% transmission. Both remarkable flexibility tested under bending stress and excellent adhesion applied on special terrain substrate have been achieved. This method has led to a full coverage of micro-holes at a depth of 18ā€‰Āµm and a bottom spacing of only 1ā€‰Āµm, as well as a perfect gap-free coverage for micro-tubes and pyramid array. It has been proved that this 3D ITO nanowire network can be used as a transparent conductive layer for optoelectronic devices with any topography surface. Through the application on the micro-holes, -tubes and -pyramid array, some new characteristics of the 3D ITO nanowires in solar cells, sensors, micro-lasers and flexible LEDs have been found. Such 3D ITO nanowire networks could be fabricated directly on micro-irregular substrates, which will greatly promote the application of the heterotypic devices

    Evidence-based Kernels: Fundamental Units of Behavioral Influence

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    This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behaviorā€“influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of its components would render it inert. Existing evidence shows that a variety of kernels can influence behavior in context, and some evidence suggests that frequent use or sufficient use of some kernels may produce longer lasting behavioral shifts. The analysis of kernels could contribute to an empirically based theory of behavioral influence, augment existing prevention or treatment efforts, facilitate the dissemination of effective prevention and treatment practices, clarify the active ingredients in existing interventions, and contribute to efficiently developing interventions that are more effective. Kernels involve one or more of the following mechanisms of behavior influence: reinforcement, altering antecedents, changing verbal relational responding, or changing physiological states directly. The paper describes 52 of these kernels, and details practical, theoretical, and research implications, including calling for a national database of kernels that influence human behavior

    Words versus actions as a means to influence cooperation in social dilemma situations

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    We use a sequential voluntary contribution game to compare the relative impact of firstmoverā€™s non-binding announcement versus binding commitment on cooperation. We find that non-binding announcement and binding commitment increase individual contributions to a similar extent. Since announced contributions systematically exceed commitments, in sessions with non-binding announcement, second-movers tend to contribute more to the group activity than in sessions with binding commitment. Yet, second-movers appear to be more motivated towards achieving a social optimum when the first-mover uses commitment. We also find that non-binding announcement has a higher impact on individual propensity to cooperate than the ex post contribution of the first-mover. However, the failure to make announced contributions decreases cooperation even though the first-mover is reassigned in every period
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