4,073 research outputs found

    Resonance line-profile calculations based on hydrodynamical models of cataclysmic variable winds

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    We present synthetic line profiles as predicted by the models of 2-D line- driven disk winds due to Proga, Stone & Drew. We compare the model line profiles with HST observations of the cataclysmic variable IX Vel. The model wind consists of a slow outflow that is bounded on the polar side by a fast stream. We find that these two components of the wind produce distinct spectral features. The fast stream produces profiles which show features consistent with observations. These include the appearance of the P-Cygni shape for a range of inclinations, the location of the maximum depth of the absorption component at velocities less than the terminal velocity, and the transition from absorption to emission with increasing inclination. However the model profiles have too little absorption or emission equivalent width. This quantitative difference between our models and observations is not a surprise because the line-driven wind models predict a mass loss rate that is lower than the rate required by the observations. We note that the model profiles exhibit a double-humped structure near the line center which is not echoed in observations. We identify this structure with a non-negligible redshifted absorption which is formed in the slow component of the wind where the rotational velocity dominates over expansion velocity. We conclude that the next generation of disk wind models, developed for application to CVs, needs to yield stronger wind driving out to larger disk radii than do the present models.Comment: LaTeX, 19 pages, to appear in Ap

    Entropy as a function of Geometric Phase

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    We give a closed-form solution of von Neumann entropy as a function of geometric phase modulated by visibility and average distinguishability in Hilbert spaces of two and three dimensions. We show that the same type of dependence also exists in higher dimensions. We also outline a method for measuring both the entropy and the phase experimentally using a simple Mach-Zehnder type interferometer which explains physically why the two concepts are related.Comment: 19 pages, 7 figure

    hMOB2 deficiency impairs homologous recombination-mediated DNA repair and sensitises cancer cells to PARP inhibitors

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    Monopolar spindle-one binder (MOBs) proteins are evolutionarily conserved and contribute to various cellular signalling pathways. Recently, we reported that hMOB2 functions in preventing the accumulation of endogenous DNA damage and a subsequent p53/p21-dependent G1/S cell cycle arrest in untransformed cells. However, the question of how hMOB2 protects cells from endogenous DNA damage accumulation remained enigmatic. Here, we uncover hMOB2 as a regulator of double-strand break (DSB) repair by homologous recombination (HR). hMOB2 supports the phosphorylation and accumulation of the RAD51 recombinase on resected single-strand DNA (ssDNA) overhangs. Physiologically, hMOB2 expression supports cancer cell survival in response to DSB-inducing anti-cancer compounds. Specifically, loss of hMOB2 renders ovarian and other cancer cells more vulnerable to FDA-approved PARP inhibitors. Reduced MOB2 expression correlates with increased overall survival in patients suffering from ovarian carcinoma. Taken together, our findings suggest that hMOB2 expression may serve as a candidate stratification biomarker of patients for HR-deficiency targeted cancer therapies, such as PARP inhibitor treatments

    Fast and Accurate Camera Covariance Computation for Large 3D Reconstruction

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    Estimating uncertainty of camera parameters computed in Structure from Motion (SfM) is an important tool for evaluating the quality of the reconstruction and guiding the reconstruction process. Yet, the quality of the estimated parameters of large reconstructions has been rarely evaluated due to the computational challenges. We present a new algorithm which employs the sparsity of the uncertainty propagation and speeds the computation up about ten times \wrt previous approaches. Our computation is accurate and does not use any approximations. We can compute uncertainties of thousands of cameras in tens of seconds on a standard PC. We also demonstrate that our approach can be effectively used for reconstructions of any size by applying it to smaller sub-reconstructions.Comment: ECCV 201

    Squeezed States of the Generalized Minimum Uncertainty State for the Caldirola-Kanai Hamiltonian

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    We show that the ground state of the well-known pseudo-stationary states for the Caldirola-Kanai Hamiltonian is a generalized minimum uncertainty state, which has the minimum allowed uncertainty ΔqΔp=σ0/2\Delta q \Delta p = \hbar \sigma_0/2, where σ0(1)\sigma_0 (\geq 1) is a constant depending on the damping factor and natural frequency. The most general symmetric Gaussian states are obtained as the one-parameter squeezed states of the pseudo-stationary ground state. It is further shown that the coherent states of the pseudo-stationary ground state constitute another class of the generalized minimum uncertainty states.Comment: RevTex4, 9 pages, no fingure; to be published in Journal of Physics

    Accurate and linear time pose estimation from points and lines

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    The final publication is available at link.springer.comThe Perspective-n-Point (PnP) problem seeks to estimate the pose of a calibrated camera from n 3Dto-2D point correspondences. There are situations, though, where PnP solutions are prone to fail because feature point correspondences cannot be reliably estimated (e.g. scenes with repetitive patterns or with low texture). In such scenarios, one can still exploit alternative geometric entities, such as lines, yielding the so-called Perspective-n-Line (PnL) algorithms. Unfortunately, existing PnL solutions are not as accurate and efficient as their point-based counterparts. In this paper we propose a novel approach to introduce 3D-to-2D line correspondences into a PnP formulation, allowing to simultaneously process points and lines. For this purpose we introduce an algebraic line error that can be formulated as linear constraints on the line endpoints, even when these are not directly observable. These constraints can then be naturally integrated within the linear formulations of two state-of-the-art point-based algorithms, the OPnP and the EPnP, allowing them to indistinctly handle points, lines, or a combination of them. Exhaustive experiments show that the proposed formulation brings remarkable boost in performance compared to only point or only line based solutions, with a negligible computational overhead compared to the original OPnP and EPnP.Peer ReviewedPostprint (author's final draft

    Gender parity in scientific authorship in a National Institute for Health Research Biomedical Research Centre: a bibliometric analysis

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    Objective Scientific authorship is a vital marker of achievement in academic careers and gender equity is a key performance metric in research. However, there is little understanding of gender equity in publications in biomedical research centres funded by the National Institute for Health Research (NIHR). This study assesses the gender parity in scientific authorship of biomedical research. Design Descriptive, cross-sectional, retrospective bibliometric study. Setting NIHR Oxford Biomedical Research Centre (BRC). Data Data comprised 2409 publications that were either accepted or published between April 2012 and March 2017. The publications were classified as basic science studies, clinical studies (both trial and non-trial studies) and other studies (comments, editorials, systematic reviews, reviews, opinions, book chapters, meeting reports, guidelines and protocols). Main outcome measures Gender of authors, defined as a binary variable comprising either male or female categories, in six authorship categories: first author, joint first authors, first corresponding author, joint corresponding authors, last author and joint last authors. Results Publications comprised 39% clinical research (n=939), 27% basic research (n=643) and 34% other types of research (n=827). The proportion of female authors as first author (41%), first corresponding authors (34%) and last author (23%) was statistically significantly lower than male authors in these authorship categories (p<0.001). Of total joint first authors (n=458), joint corresponding authors (n=169) and joint last authors (n=229), female only authors comprised statistically significant (p<0.001) smaller proportions, that is, 15% (n=69), 29% (n=49) and 10% (n=23) respectively, compared with male only authors in these joint authorship categories. There was a statistically significant association between gender of the last author with gender of the first author (p<0.001), first corresponding author (p<0.001) and joint last author (p<0.001). The mean journal impact factor (JIF) was statistically significantly higher when the first corresponding author was male compared with female (Mean JIF: 10.00 vs 8.77, p=0.020); however, the JIF was not statistically different when there were male and female authors as first authors and last authors. Conclusions Although the proportion of female authors is significantly lower than the proportion of male authors in all six categories of authorship analysed, the proportions of male and female last authors are comparable to their respective proportions as principal investigators in the BRC. These findings suggest positive trends and the NIHR Oxford BRC doing very well in gender parity in the senior (last) authorship category. Male corresponding authors are more likely to publish articles in prestigious journals with high impact factor while both male and female authors at first and last authorship positions publish articles in equally prestigious journals

    Three manifestations of the pulsed harmonic potential

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    We consider, in turn, three systems being acted upon by a regularly pulsed harmonic potential (PHP). These are i) a classical particle, ii) a quantum particle, and iii) a directed line. We contrast the mechanics of the first two systems by parameterizing their bands of stability and periodicity. Interesting differences due to quantum fluctuations are examined in detail. The fluctuations of the directed line are calculated in the two cases of a binding PHP, and an unbinding PHP. In the latter case there is a finite maximum line length for a given potential strength.Comment: 34 Revtex pages, with 5 attached figure
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