6,378 research outputs found

    The distribution and movement patterns of four woodland caribou herds in Quebec and Labrador

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    Recent studies of woodland caribou (Rangifer tarandus caribou) in northern Quebec and central Labrador have demonstrated similar patterns of seasonal movements and distribution among four herds. Aerial surveys and radio-telemetry indicated that animals occupied forest-wetland habitat at densities of 0.03 caribou km2, or lower, for most of the year. Although females were widely dispersed at calving individuals demonstrated fidelity toward specific calving locations, in successive years. Caribou did not form large post-calving aggregations. Movement was greatest in the spring, prior to calving, and in the fall, during or immediately after rutting. Caribou were generally sedentary during summer and winter, although some moved relatively long distances to late-winter range. Although the herds occupy continuous range across Quebec and Labrador, our data indicate that the herds are largely discreete and should be managed individually

    Protocol for a feasibility study of smoking cessation in the surgical pathway before major lung surgery: Project MURRAY

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    INTRODUCTION: Smoking prior to major thoracic surgery is the biggest risk factor for development of postoperative pulmonary complications, with one in five patients continuing to smoke before surgery. Current guidance is that all patients should stop smoking before elective surgery yet very few are offered specialist smoking cessation support. Patients would prefer support within the thoracic surgical pathway. No study has addressed the effectiveness of such an intervention in this setting on cessation. The overall aim is to determine in patients who undergo major elective thoracic surgery whether an intervention integrated (INT) into the surgical pathway improves smoking cessation rates compared with usual care (UC) of standard community/hospital based NHS smoking support. This pilot study will evaluate feasibility of a substantive trial. METHODS AND ANALYSIS: Project MURRAY is a trial comparing the effectiveness of INT and UC on smoking cessation. INT is pharmacotherapy and a hybrid of behavioural support delivered by the trained healthcare practitioners (HCPs) in the thoracic surgical pathway and a complimentary web-based application. This pilot study will evaluate the feasibility of a substantive trial and study processes in five adult thoracic centres including the University Hospitals Birmingham NHS Foundation Trust. The primary objective is to establish the proportion of those eligible who agree to participate. Secondary objectives include evaluation of study processes. Analyses of feasibility and patient-reported outcomes will take the form of simple descriptive statistics and where appropriate, point estimates of effects sizes and associated 95% CIs. ETHICS AND DISSEMINATION: The study has obtained ethical approval from NHS Research Ethics Committee (REC number 19/WM/0097). Dissemination plan includes informing patients and HCPs; engaging multidisciplinary professionals to support a proposal of a definitive trial and submission for a full application dependent on the success of the study. TRIAL REGISTRATION NUMBER: NCT04190966

    Modelling the clumping-induced polarimetric variability of hot star winds

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    Clumping in the winds of massive stars may significantly reduce empirical mass-loss rates, and which in turn may have a large impact on our understanding of massive star evolution. Here, we investigate wind-clumping through the linear polarization induced by light scattering off the clumps. Through the use of an analytic wind clumping model, we predict the time evolution of the linear polarimetry over a large parameter space. We concentrate on the Luminous Blue Variables, which display the greatest amount of polarimetric variability and for which we recently conducted a spectropolarimetric survey. Our model results indicate that the observed level of polarimetric variability can be reproduced for two regimes of parameter space: one of a small number of massive, optically-thick clumps; and one of a very large number of low-mass clumps. Although a systematic time-resolved monitoring campaign is required to distinguish between the two scenarios, we currently favour the latter, given the short timescale of the observed polarization variability. As the polarization is predicted to scale linearly with mass-loss rate, we anticipate that all hot stars with very large mass-loss rates should display polarimetric variability. This is consistent with recent findings that intrinsic polarization is more common in stars with strong Hα\alpha emission.Comment: 12 pages, 11 figures, accepted to A&

    Gene Function Classification Using Bayesian Models with Hierarchy-Based Priors

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    We investigate the application of hierarchical classification schemes to the annotation of gene function based on several characteristics of protein sequences including phylogenic descriptors, sequence based attributes, and predicted secondary structure. We discuss three Bayesian models and compare their performance in terms of predictive accuracy. These models are the ordinary multinomial logit (MNL) model, a hierarchical model based on a set of nested MNL models, and a MNL model with a prior that introduces correlations between the parameters for classes that are nearby in the hierarchy. We also provide a new scheme for combining different sources of information. We use these models to predict the functional class of Open Reading Frames (ORFs) from the E. coli genome. The results from all three models show substantial improvement over previous methods, which were based on the C5 algorithm. The MNL model using a prior based on the hierarchy outperforms both the non-hierarchical MNL model and the nested MNL model. In contrast to previous attempts at combining these sources of information, our approach results in a higher accuracy rate when compared to models that use each data source alone. Together, these results show that gene function can be predicted with higher accuracy than previously achieved, using Bayesian models that incorporate suitable prior information

    Speciation of OH reactivity above the canopy of an isoprene-dominated forest

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    Measurements of OH reactivity, the inverse lifetime of the OH radical, can provide a top–down estimate of the total amount of reactive carbon in an air mass. Using a comprehensive measurement suite, we examine the measured and modeled OH reactivity above an isoprene-dominated forest in the southeast United States during the 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign. Measured and modeled species account for the vast majority of average daytime reactivity (80–95 %) and a smaller portion of nighttime and early morning reactivity (68–80 %). The largest contribution to total reactivity consistently comes from primary biogenic emissions, with isoprene contributing ∼  60 % in the afternoon, and ∼  30–40 % at night and monoterpenes contributing ∼  15–25 % at night. By comparing total reactivity to the reactivity stemming from isoprene alone, we find that ∼  20 % of the discrepancy is temporally related to isoprene reactivity, and an additional constant ∼  1 s^(−1) offset accounts for the remaining portion. The model typically overestimates measured OVOC concentrations, indicating that unmeasured oxidation products are unlikely to influence measured OH reactivity. Instead, we suggest that unmeasured primary emissions may influence the OH reactivity at this site

    Three-dimensional Explosion Geometry of Stripped-envelope Core-collapse Supernovae. II. Modeling of Polarization

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    We present modeling of line polarization to study the multidimensional geometry of stripped-envelope core-collapse supernovae (SNe). We demonstrate that a purely axisymmetric, two-dimensional (2D) geometry cannot reproduce a loop in the Stokes Q - U diagram, that is, a variation of the polarization angles along the velocities associated with the absorption lines. On the contrary, three-dimensional (3D) clumpy structures naturally reproduce the loop. The fact that the loop is commonly observed in stripped-envelope SNe suggests that SN ejecta generally have a 3D structure. We study the degree of line polarization as a function of the absorption depth for various 3D clumpy models with different clump sizes and covering factors. A comparison between the calculated and observed degree of line polarization indicates that a typical size of the clump is relatively large, ≈25% of the photospheric radius. Such large-scale clumps are similar to those observed in the SN remnant Cassiopeia A. Given the small size of the observed sample, the covering factor of the clumps is only weakly constrained (∼5%-80%). The presence of a large-scale clumpy structure suggests that the large-scale convection or standing accretion shock instability takes place at the onset of the explosion. © 2017. The American Astronomical Society. All rights reserved

    Infinite Nuclear Matter on the Light Front: Nucleon-Nucleon Correlations

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    A relativistic light front formulation of nuclear dynamics is developed and applied to treating infinite nuclear matter in a method which includes the correlations of pairs of nucleons: this is light front Brueckner theory. We start with a hadronic meson-baryon Lagrangian that is consistent with chiral symmetry. This is used to obtain a light front version of a one-boson-exchange nucleon-nucleon potential (OBEP). The accuracy of our description of the nucleon-nucleon (NN) data is good, and similar to that of other relativistic OBEP models. We derive, within the light front formalism, the Hartree-Fock and Brueckner Hartree-Fock equations. Applying our light front OBEP, the nuclear matter saturation properties are reasonably well reproduced. We obtain a value of the compressibility, 180 MeV, that is smaller than that of alternative relativistic approaches to nuclear matter in which the compressibility usually comes out too large. Because the derivation starts from a meson-baryon Lagrangian, we are able to show that replacing the meson degrees of freedom by a NN interaction is a consistent approximation, and the formalism allows one to calculate corrections to this approximation in a well-organized manner. The simplicity of the vacuum in our light front approach is an important feature in allowing the derivations to proceed. The mesonic Fock space components of the nuclear wave function are obtained also, and aspects of the meson and nucleon plus-momentum distribution functions are computed. We find that there are about 0.05 excess pions per nucleon.Comment: 39 pages, RevTex, two figure

    Time evolution of models described by one-dimensional discrete nonlinear Schr\"odinger equation

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    The dynamics of models described by a one-dimensional discrete nonlinear Schr\"odinger equation is studied. The nonlinearity in these models appears due to the coupling of the electronic motion to optical oscillators which are treated in adiabatic approximation. First, various sizes of nonlinear cluster embedded in an infinite linear chain are considered. The initial excitation is applied either at the end-site or at the middle-site of the cluster. In both the cases we obtain two kinds of transition: (i) a cluster-trapping transition and (ii) a self-trapping transition. The dynamics of the quasiparticle with the end-site initial excitation are found to exhibit, (i) a sharp self-trapping transition, (ii) an amplitude-transition in the site-probabilities and (iii) propagating soliton-like waves in large clusters. Ballistic propagation is observed in random nonlinear systems. The effect of nonlinear impurities on the superdiffusive behavior of random-dimer model is also studied.Comment: 16 pages, REVTEX, 9 figures available upon request, To appear in Physical Review

    In-medium relativistic kinetic theory and nucleon-meson systems

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    Within the σ−ω\sigma-\omega model of coupled nucleon-meson systems, a generalized relativistic Lenard--Balescu--equation is presented resulting from a relativistic random phase approximation (RRPA). This provides a systematic derivation of relativistic transport equations in the frame of nonequilibrium Green's function technique including medium effects as well as flucuation effects. It contains all possible processes due to one meson exchange and special attention is kept to the off--shell character of the particles. As a new feature of many particle effects, processes are possible which can be interpreted as particle creation and annihilation due to in-medium one meson exchange. In-medium cross sections are obtained from the generalized derivation of collision integrals, which possess complete crossing symmetries.Comment: See nucl-th/9310032 for revised version which the authors incompetently resubmitted rather than correctly replacing thi

    Efficacy and safety of a novel delayed-release risedronate 35 mg once-a-week tablet

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    Dosing regimens of oral bisphosphonates are inconvenient and contribute to poor compliance. The bone mineral density response to a once weekly delayed-release formulation of risedronate given before or following breakfast was non-inferior to traditional immediate-release risedronate given daily before breakfast. Delayed-release risedronate is a convenient regimen for oral bisphosphonate therapy
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