24,461 research outputs found

    An index theorem in differential K-theory

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    Let X --> B be a proper submersion with a Riemannian structure. Given a differential K-theory class on X, we define its analytic and topological indices as differential K-theory classes on B. We prove that the two indices are the same.Comment: 65 pages; version 2 has small changes for publicatio

    An \u3cem\u3eIn Vitro\u3c/em\u3e Spectroscopic Analysis to Determine Whether Para-Chloroaniline Is Produced from Mixing Sodium Hypochlorite and Chlorhexidine

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    Introduction: The purpose of this in vitro study was to determine whether para-chloroaniline (PCA) is formed through the reaction of mixing sodium hypochlorite (NaOCl) and chlorhexidine (CHX). Methods: Initially, commercially available samples of chlorhexidine acetate (CHXa) and PCA were analyzed with 1H nuclear magnetic resonance (NMR) spectroscopy. Two solutions, NaOCl and CHXa, were warmed to 37ÂșC, and when mixed they produced a brown precipitate. This precipitate was separated in half, and pure PCA was added to 1 of the samples for comparison before they were each analyzed with 1H NMR spectroscopy. Results: The peaks in the 1H NMR spectra of CHXa and PCA were assigned to specific protons of the molecules, and the location of the aromatic peaks in the PCA spectrum defined the PCA doublet region. Although the spectrum of the precipitate alone resulted in a complex combination of peaks, on magnification there were no peaks in the PCA doublet region that were intense enough to be quantified. In the spectrum of the precipitate to which PCA was added, 2 peaks do appear in the PCA doublet region. Comparing this spectrum with that of precipitate alone, the peaks in the PCA doublet region are not visible before the addition of PCA. Conclusions: On the basis of this in vitro study, the reaction mixture of NaOCl and CHXa does not produce PCA at any measurable quantity, and further investigation is needed to determine the chemical composition of the brown precipitate

    Performance Pay and the White-Black Wage Gap

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    We show that the reported tendency for performance pay to be associated with greater wage inequality at the top of the earnings distribution applies only to white workers. This results in the white-black wage differential among those in performance pay jobs growing over the earnings distribution even as the same differential shrinks over the distribution for those not in performance pay jobs. We show this remains true even when examining suitable counterfactuals that hold observables constant between whites and blacks. We explore reasons behind our finding that performance pay is associated with greater racial earnings gaps at the top of the wage distribution focusing on the interactions between discrimination, unmeasured ability and selection.Racial wage differentials, compensation practices

    Performance Pay and the White-Black Wage Gap

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    We show that the reported tendency for performance pay to be associated with greater wage inequality at the top of the earnings distribution applies only to white workers. This results in the white-black wage differential among those in performance pay jobs growing over the earnings distribution even as the same differential shrinks over the distribution for those not in performance pay jobs. We show this remains true even when examining suitable counterfactuals that hold observables constant between whites and blacks. We explore reasons behind our finding that performance pay is associated with greater racial earnings gaps at the top of the wage distribution focusing on the interactions between discrimination, unmeasured ability and selection.Racial Wage Differentials, Compensation Practices

    Compensating Wage Differentials and the Duration of Wage Loss

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    Several reasons are offered why workers will receive larger compensating wage differentials for increases in the duration of wage losses than for increases in the probability of loss that produce the same expected loss. A formal model of occupational choice is developed that shows the extent to which the compensation for increased duration exceeds that for increased risk. Using Panel Study of Income Dynamics data linked to industry data on injuries and unemployment, we find:1) Nearly all the compensating wage differential for losses due to workplace injuries is compensation for increases in the duration of loss; 2) Similarly, nearly all the compensation for losses due to cyclical unemployment is compensation for increases in duration, especially for increases in duration beyond the 26 weeks of unemployment that are usually compensated by unemployment insurance. The compensating differentials for risk of injury are larger for union than for nonunion workers, while those for cyclical unemployment are smaller for union workers.

    Topology and Nematic Ordering II: Observable Critical Behavior

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    This paper is the second in a pair treating a new lattice model for nematic media. In addition to the familiar isotropic (I) and nematically ordered (N) phases, the phase diagram established in the previous paper (Paper I) contains a new, topologically ordered phase (T) occuring at large suppression of topological defects and weak nematic interactions. This paper (Paper II) is concerned with the experimental signatures of the proposed phase diagram. Specific heat, light scattering and magnetic susceptibility near both the N/T and I/T transitions are studied, and critical behavior determined. The singular dependences of the Frank constants (K1K_1, K2K_2, K3K_3) and the dielectric tensor anisotropy (Δϔ\Delta \epsilon) on temperature upon approaching the N/T transition are also found.Comment: 10 pages, RevTeX 3.

    Centerscope

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    Centerscope, formerly Scope, was published by the Boston University Medical Center "to communicate the concern of the Medical Center for the development and maintenance of improved health care in contemporary society.

    Consumer Response to Genetically Modified Foods

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    The consumer trait and characteristic identification, and corresponding relationship to the genetically modified food product's negative reactions was determined from a 354 respondent, 130 item mailed survey. The survey and partially mediated model from Mowen's 3M Model of Personality and Motivation explained how personality traits influence genetically modified food reactions.Consumer/Household Economics,

    Streamwise forced oscillations of circular and square cylinders

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    The modification of a cylinder wake by streamwise oscillation of the cylinder at the vortex shedding frequency of the unperturbed cylinder is reported. Recent numerical simulations [J. S. Leontini, D. Lo Jacono, and M. C. Thompson, “A numerical study of an inline oscillating cylinder in a free stream,” J. Fluid Mech. 688, 551–568 (2011)] showed that this forcing results in the primary frequency decreasing proportionally to the square of the forcing amplitude, before locking to a subharmonic at higher amplitudes. The experimental results presented here show that this behavior continues at higher Reynolds numbers, although the flow is three-dimensional. In addition, it is shown that this behavior persists when the body is a square cross section, and when the frequency of forcing is detuned from the unperturbed cylinder shedding frequency. The similarity of the results across Reynolds number, geometry, and frequency suggests that the physical mechanism is applicable to periodic forcing of the classic von Ka ́rma ́n vortex street, regardless of the details of the body which forms the street

    Beyond the information technology agreement : harmonization of standards and trade in electronics

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    Product standards can have a dual impact on production and trade costs. Standards may impose additional costs on exporters as it may be necessary to adapt products for specific markets (cost-effect). In contrast, standards can reduce exporters'information costs if they convey information on industrial requirements or consumer tastes that would be costly to collect in the absence of standards (informational-effect). Using a new World Bank database of European standards for electronic products, the authors examine the impact of internationally-harmonized European standards on European Union imports. They find that European Union standards for electronic products that are harmonized to international standards have a positive and significant effect on trade. The results suggest that efforts to promote trade in electronic products could be complemented by steps to promote standards harmonization. This might include, for example, re-starting talks to extend the Information Technology Agreement to non-tariff measures and commitments to harmonize national standards in electronic products.Information Security&Privacy,Technology Industry,Scientific Research&Science Parks,Science Education,Labor Policies
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