613 research outputs found

    Picosecond real-time studies of mode-specific vibrational predissociation

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    The vibrational predissociation of several van der Waals complexes of t-stilbene has been studied by directly measuring, in real time, the fluorescence intensity from the initial reactant state and from the individual product states formed in the dissociation process after exciting single vibrational levels of the complex. With the aid of a kinetic model involving sequential processes, the individual rates for intramolecular vibrational redistribution and vibrational predissociation in the overall dissociation process are resolved and distinguished in several cases. In the stilbene–He complex, the dissociation is significantly faster from low energy out-of-plane modes than it is from a higher energy in-plane mode

    Turning up by turning over : the change of scenery effect in major league baseball

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    Purpose: This study examined a “change of scenery” effect on performance in major league baseball (MLB). We also tested this effect for voluntary versus involuntary employee departures, as well as employees returning to a past employer. Design/Methodology/Approach: This study uses publicly available MLB performance data from 2004 to 2015. The data comprise 712 team changes for players following two consecutive years with the same organization. Data were analyzed using MANCOVA to assess the impact of changing teams on player performance. Findings: Results indicate players with declining performance benefited significantly from a change of scenery. Following a team change, these players experienced a significant increase in their performance that remained stable through a subsequent season. The effect was not different for players who changed teams via trade and free agency and was modest for those returning to a past organization. Analysis also showed that players leaving while their performance was improving suffered a subsequent performance drop-off in the new organization. Implications: As the war for talent escalates and employees change jobs more frequently, extending our understanding of how performance can be influenced by work context may provide new insight into organization staffing policies. Originality/Value: Results extend field theory by highlighting how past performance interacts with new work contexts to influence performance. This is one of the few studies evaluating the job change-performance relationship, and perhaps the first to account for the effects of performance trends prior to exit

    Optical to near-infrared transmission spectrum of the warm sub-Saturn HAT-P-12b

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    We present the transmission spectrum of HAT-P-12b through a joint analysis of data obtained from the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) and Wide Field Camera 3 (WFC3) and Spitzer, covering the wavelength range 0.3-5.0 μ\mum. We detect a muted water vapor absorption feature at 1.4 μ\mum attenuated by clouds, as well as a Rayleigh scattering slope in the optical indicative of small particles. We interpret the transmission spectrum using both the state-of-the-art atmospheric retrieval code SCARLET and the aerosol microphysics model CARMA. These models indicate that the atmosphere of HAT-P-12b is consistent with a broad range of metallicities between several tens to a few hundred times solar, a roughly solar C/O ratio, and moderately efficient vertical mixing. Cloud models that include condensate clouds do not readily generate the sub-micron particles necessary to reproduce the observed Rayleigh scattering slope, while models that incorporate photochemical hazes composed of soot or tholins are able to match the full transmission spectrum. From a complementary analysis of secondary eclipses by Spitzer, we obtain measured depths of 0.042%±0.013%0.042\%\pm0.013\% and 0.045%±0.018%0.045\%\pm0.018\% at 3.6 and 4.5 μ\mum, respectively, which are consistent with a blackbody temperature of 89070+60890^{+60}_{-70} K and indicate efficient day-night heat recirculation. HAT-P-12b joins the growing number of well-characterized warm planets that underscore the importance of clouds and hazes in our understanding of exoplanet atmospheres.Comment: 25 pages, 19 figures, accepted for publication in AJ, updated with proof correction

    van der Waals density functional calculations of binding in molecular crystals

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    A recent paper [J. Chem. Phys. 132, 134705 (2010)] illustrated the potential of the van der Waals density functional (vdW-DF) method [Phys. Rev. Lett. 92, 246401 (2004)] for efficient first-principle accounts of structure and cohesion in molecular crystals. Since then, modifications of the original vdW-DF version (identified as vdW-DF1) has been proposed, and there is also a new version called vdW-DF2 [ArXiv 1003.5255], within the vdW-DF framework. Here we investigate the performance and nature of the modifications and the new version for the binding of a set of simple molecular crystals: hexamine, dodecahedrane, C60, and graphite. These extended systems provide benchmarks for computational methods dealing with sparse matter. We show that a previously documented enhancement of non-local correlations of vdW-DF1 over an asymptotic atom-based account close to and a few A, beyond binding separation persists in vdW-DF2. The calculation and analysis of the binding in molecular crystals requires appropriate computational tools. In this paper, we also present details on our real-space parallel implementation of the vdW-DF correlation and on the method used to generate asymptotic atom-based pair potentials based on vdW-DF.Comment: 5 pages, 4 figure

    Plasma Persistence of 2-Aminothiazoline-4-Carboxylic Acid in Rat System Determined by Liquid Chromatography Tandem Mass Spectrometry

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    2-Aminothiazoline-4-carboxylic acid (ATCA) was intravenously injected to rats in order to investigate its plasma distribution. ATCA was extracted from plasma samples by solid phase extraction (SPE) and molecularly imprinted polymer stir bar sorption extraction (MIP-SBSE). Detection and quantification of ATCA were achieved by using liquid chromatography–tandem mass spectrometry (LC–MS/MS). It was found that the intravenously injected ATCA concentration quickly decreased to half within 2.5 h in the rat system. However, after 2.5 h, the concentration of ATCA in plasma stayed constant at least 5 folds above the endogenous ATCA level for more then 48 h. This finding can be used for evaluating ATCA\u27s diagnostic and forensic value as a biomarker for cyanide exposure

    Site Environmental Report for 2011, Volumes 1& 2

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    The Site Environmental Report for 2011 summarizes Berkeley Lab’s environmental management performance, presents environmental monitoring results, and describes significant programs for calendar year (CY) 2011. Throughout this report, “Berkeley Lab” or “LBNL” refers both to (1) the multiprogram scientific facility the UC manages and operates on the 202-acre university-owned site located in the hills above the UC Berkeley campus, and the site itself, and (2) the UC as managing and operating contractor for Ernest Orlando Lawrence Berkeley National Laboratory. The report is separated into two volumes. Volume I is organized into an executive summary followed by six chapters that include an overview of LBNL, a discussion of its Environmental Management System (EMS), the status of environmental programs, summarized results from surveillance and monitoring activities, and quality assurance (QA) measures. Volume II contains individual data results from surveillance and monitoring activities

    Live-Cell Imaging of Cellular Proteins by a Strain-Promoted Azide–Alkyne Cycloaddition

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    Live and let dye: Three coumarin-cyclooctyne conjugates have been used to label proteins tagged with azidohomoalanine in Rat-1 fibroblasts. All three fluorophores labeled intracellular proteins with fluorescence enhancements ranging from eight- to 20-fold. These conjugates are powerful tools for visualizing biomolecule dynamics in living cells
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