953 research outputs found

    A Note on the Green Dyadic Calculation of the Decay Rates for Admolecules at Multiple Planar Interfaces

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    The Green dyadic formulation for calculating classical decay rates of admolecules at multiple planar interfaces first published by Chance, Prock and Silbey is reexamined. It is pointed out that, for the case of fluorescing molecules sandwiched between a system of super- and substrate interfaces, the original formalism requires significant modifications in order to lead to results consistent with those obtained from the Sommerfeld radiation theory

    Analysis of Affymetrix GeneChip Data Using Amplified RNA

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    The standard method of target synthesis for hybridization to Affymetrix GeneChipÂź expression microarrays requires a relatively large amount of input total RNA (1-15 micrograms). When small biological samples are collected by microdissection or other methods, amplification techniques are required to provide sufficient target for hybridization to expression arrays. One amplification technique used is to perform two successive rounds of T7-based in vitro transcription. However, the use of random primers required to re-generate cDNA from the first round transcription reaction results in shortened copies of the cDNA, and ultimately the cRNA, transcripts from which the 5\u27 end is missing. In this paper we describe an experiment designed to compare the quality of data obtained from labeling small RNA samples using the Affymetrix Small Sample Target Labeling Protocol V 2 to that of data obtained using the standard protocol. We utilized different preprocessing algorithms to compare the data generated using both labeling methods and present a new algorithm that improves upon existing ones in this setting

    Supporting Family Physician Maternity Care Providers

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    Maternity care access in the United States is in crisis. The American Congress of Obstetrics and Gynecology projects that by 2030 there will be a nationwide shortage of 9,000 obstetrician-gynecologists (OB/GYNs). Midwives and OB/GYNs have been called upon to address this crisis, yet in underserved areas, family physicians are often providing a majority of this care. Family medicine maternity care, a natural fit for the discipline, has been on sharp decline in recent years for many reasons including difficulties cultivating interdisciplinary relationships, navigating privileging, developing and maintaining adequate volume/competency, and preventing burnout. In 2016 and 2017, workshops were held among family medicine educators with resultant recommendations for essential strategies to support family physician maternity care providers. This article summarizes these strategies, provides guidance, and highlights the role family physicians have in addressing maternity care access for the underserved as well as presenting innovative ideas to train and retain rural family physician maternity care providers

    From M-ary Query to Bit Query: a new strategy for efficient large-scale RFID identification

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    The tag collision avoidance has been viewed as one of the most important research problems in RFID communications and bit tracking technology has been widely embedded in query tree (QT) based algorithms to tackle such challenge. Existing solutions show further opportunity to greatly improve the reading performance because collision queries and empty queries are not fully explored. In this paper, a bit query (BQ) strategy based Mary query tree protocol (BQMT) is presented, which can not only eliminate idle queries but also separate collided tags into many small subsets and make full use of the collided bits. To further optimize the reading performance, a modified dual prefixes matching (MDPM) mechanism is presented to allow multiple tags to respond in the same slot and thus significantly reduce the number of queries. Theoretical analysis and simulations are supplemented to validate the effectiveness of the proposed BQMT and MDPM, which outperform the existing QT-based algorithms. Also, the BQMT and MDPM can be combined to BQMDPM to improve the reading performance in system efficiency, total identification time, communication complexity and average energy cost

    Implications of Cosmological Gamma-Ray Absorption II. Modification of gamma-ray spectra

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    Bearing on the model for the time-dependent metagalactic radiation field developed in the first paper of this series, we compute the gamma-ray attenuation due to pair production in photon-photon scattering. Emphasis is on the effects of varying the star formation rate and the fraction of UV radiation assumed to escape from the star forming regions, the latter being important mainly for high-redshift sources. Conversely, we investigate how the metagalactic radiation field can be measured from the gamma-ray pair creation cutoff as a function of redshift, the Fazio-Stecker relation. For three observed TeV-blazars (Mkn501, Mkn421, H1426+428) we study the effects of gamma-ray attenuation on their spectra in detail.Comment: 10 pages, 6 figures, accepted by A&

    A kinematic study of the compact jet in quasar B3 1633+382

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    We present a study of the motion of compact jet components in quasar B3 1633+382. Through analyzing 14 epochs of VLBI observations of three components (B1, B2, and B3) at 22 GHz, we find two different possibilities of component classification. Thus two corresponding kinematical models can be adopted to explain the evolutionary track of components. One is a linear motion, while another is a helical model. Future observations are needed to provide new kinematical constraints for the motion of these components in this source.Comment: 7 pages, 3 figures; Accepted for publication in A&

    Lower Rotational Inertia and Larger Leg Muscles Indicate More Rapid Turns in Tyrannosaurids Than in Other Large Theropods

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    Synopsis: Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (\u3e400 kg), toothed dinosaurian predator niches in their habitats

    The necessity and possibility of powerful ‘regional’ knowledge: curriculum change and renewal

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    © 2016 Taylor & Francis. The paper argues that powerful regional knowledge is necessary and possible and that there are historical precedents supporting these claims. Regional knowledge is being used in a double sense: the first Bernsteinian, the second in relation to knowledge generated outside the academy. Both are important if the debate is not to be confined solely to the global north and if the curriculum is to be responsive to geo-political realities. In order to think critically about access to higher education, we need to consider the sorts of knowledge, engagement, and opportunities that are open to newer actors. This includes recognising the contextual nature of professional practice and also that social movements beyond the academy can and do challenge academic knowledge. The paper concludes that many of issues addressed are not capable of theoretical resolution alone and that we need more empirical work to inform curriculum change and renewal

    A low density of 0.8 g/cc for the Trojan binary asteroid 617 Patroclus

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    The Trojan population consists of two swarms of asteroids following the same orbit as Jupiter and located at the L4 and L5 Lagrange points of the Jupiter-Sun system (leading and following Jupiter by 60 degrees). The asteroid 617 Patroclus is the only known binary Trojan (Merline et al. 2001). The orbit of this double system was hitherto unknown. Here we report that the components, separated by 680 km, move around the system centre of mass, describing roughly a circular orbit. Using the orbital parameters, combined with thermal measurements to estimate the size of the components, we derive a very low density of 0.8 g/cc. The components of Patroclus are therefore very porous or composed mostly of water ice, suggesting that they could have been formed in the outer part of the solar system.Comment: 10 pages, 3 figures, 1 tabl
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