1,741 research outputs found

    Large-Scale Image Processing with the ROTSE Pipeline for Follow-Up of Gravitational Wave Events

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    Electromagnetic (EM) observations of gravitational-wave (GW) sources would bring unique insights into a source which are not available from either channel alone. However EM follow-up of GW events presents new challenges. GW events will have large sky error regions, on the order of 10-100 square degrees, which can be made up of many disjoint patches. When searching such large areas there is potential contamination by EM transients unrelated to the GW event. Furthermore, the characteristics of possible EM counterparts to GW events are also uncertain. It is therefore desirable to be able to assess the statistical significance of a candidate EM counterpart, which can only be done by performing background studies of large data sets. Current image processing pipelines such as that used by ROTSE are not usually optimised for large-scale processing. We have automated the ROTSE image analysis, and supplemented it with a post-processing unit for candidate validation and classification. We also propose a simple ad hoc statistic for ranking candidates as more likely to be associated with the GW trigger. We demonstrate the performance of the automated pipeline and ranking statistic using archival ROTSE data. EM candidates from a randomly selected set of images are compared to a background estimated from the analysis of 102 additional sets of archival images. The pipeline's detection efficiency is computed empirically by re-analysis of the images after adding simulated optical transients that follow typical light curves for gamma-ray burst afterglows and kilonovae. We show that the automated pipeline rejects most background events and is sensitive to simulated transients to limiting magnitudes consistent with the limiting magnitude of the images

    Electrochemical Treatment of Mixed and Hazardous Waste

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    Los Alamos National Laboratory (LANL) and The University of New Mexico are jointly developing an electrochemical process for treating hazardous and radioactive wastes. The wastes treatable by the process include toxic metal solutions, cyanide solutions, and various organic wastes that may contain chlorinated organic compounds. The main component of the process is a stack of electrolytic cells with peripheral equipment such as a rectifier, feed system, tanks with feed and treated solutions, and a gas-venting system. During the treatment, toxic metals are deposited on the cathode, cyanides are oxidized on the anode, and organic compounds are anodically oxidized by direct or mediated electrooxidation, depending on their type. Bench scale experimental studies have confirmed the feasibility of applying electrochemical systems to processing of a great variety of hazardous and mixed wastes. The operating parameters have been defined for different waste compositions using surrogate wastes. Mixed wastes are currently treated at bench scale as part of the treatability study

    Neuronal regulation of cochlear blood flow in the guinea‐pig.

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110011/1/tjp19944803563.pd

    Enhancing gravitational wave astronomy with galaxy catalogues

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    Joint gravitational wave (GW) and electromagnetic (EM) observations, as a key research direction in multi-messenger astronomy, will provide deep insight into the astrophysics of a vast range of astronomical phenomena. Uncertainties in the source sky location estimate from gravitational wave observations mean follow-up observatories must scan large portions of the sky for a potential companion signal. A general frame of joint GW-EM observations is presented by a multi-messenger observational triangle. Using a Bayesian approach to multi-messenger astronomy, we investigate the use of galaxy catalogue and host galaxy information to reduce the sky region over which follow-up observatories must scan, as well as study its use for improving the inclination angle estimates for coalescing binary compact objects. We demonstrate our method using a simulated neutron stars inspiral signal injected into simulated Advanced detectors noise and estimate the injected signal sky location and inclination angle using the Gravitational Wave Galaxy Catalogue. In this case study, the top three candidates in rank have 72%72\%, 15%15\% and 8%8\% posterior probability of being the host galaxy, receptively. The standard deviation of cosine inclination angle (0.001) of the neutron stars binary using gravitational wave-galaxy information is much smaller than that (0.02) using only gravitational wave posterior samples.Comment: Proceedings of the Sant Cugat Forum on Astrophysics. 2014 Session on 'Gravitational Wave Astrophysics

    Universal Window for Two Dimensional Critical Exponents

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    Two dimensional condensed matter is realised in increasingly diverse forms that are accessible to experiment and of potential technological value. The properties of these systems are influenced by many length scales and reflect both generic physics and chemical detail. To unify their physical description is therefore a complex and important challenge. Here we investigate the distribution of experimentally estimated critical exponents, β\beta, that characterize the evolution of the order parameter through the ordering transition. The distribution is found to be bimodal and bounded within a window 0.1β0.25\sim 0.1 \le \beta \le 0.25, facts that are only in partial agreement with the established theory of critical phenomena. In particular, the bounded nature of the distribution is impossible to reconcile with existing theory for one of the major universality classes of two dimensional behaviour - the XY model with four fold crystal field - which predicts a spectrum of non-universal exponents bounded only from below. Through a combination of numerical and renormalization group arguments we resolve the contradiction between theory and experiment and demonstrate how the "universal window" for critical exponents observed in experiment arises from a competition between marginal operators.Comment: 26 pages, 5 figures and 6 tables. Uses longtable packag

    A List of Galaxies for Gravitational Wave Searches

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    We present a list of galaxies within 100 Mpc, which we call the Gravitational Wave Galaxy Catalogue (GWGC), that is currently being used in follow-up searches of electromagnetic counterparts from gravitational wave searches. Due to the time constraints of rapid follow-up, a locally available catalogue of reduced, homogenized data is required. To achieve this we used four existing catalogues: an updated version of the Tully Nearby Galaxy Catalog, the Catalog of Neighboring Galaxies, the V8k catalogue and HyperLEDA. The GWGC contains information on sky position, distance, blue magnitude, major and minor diameters, position angle, and galaxy type for 53,255 galaxies. Errors on these quantities are either taken directly from the literature or estimated based on our understanding of the uncertainties associated with the measurement method. By using the PGC numbering system developed for HyperLEDA, the catalogue has a reduced level of degeneracies compared to catalogues with a similar purpose and is easily updated. We also include 150 Milky Way globular clusters. Finally, we compare the GWGC to previously used catalogues, and find the GWGC to be more complete within 100 Mpc due to our use of more up-to-date input catalogues and the fact that we have not made a blue luminosity cut.Comment: Accepted for publication in Classical and Quantum Gravity, 13 pages, 7 figure

    Association of A1C and Fasting Plasma Glucose Levels With Diabetic Retinopathy Prevalence in the U.S. Population: Implications for diabetes diagnostic thresholds

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    Abstract OBJECTIVE To examine the association of A1C levels and fasting plasma glucose (FPG) with diabetic retinopathy in the U.S. population and to compare the ability of the two glycemic measures to discriminate between people with and without retinopathy. RESEARCH DESIGN AND METHODS This study included 1,066 individuals aged ≥40 years from the 2005–2006 National Health and Nutrition Examination Survey. A1C, FPG, and 45° color digital retinal images were assessed. Retinopathy was defined as a level ≥14 on the Early Treatment Diabetic Retinopathy Study severity scale. We used joinpoint regression to identify linear inflections of prevalence of retinopathy in the association between A1C and FPG. RESULTS The overall prevalence of retinopathy was 11%, which is appreciably lower than the prevalence in people with diagnosed diabetes (36%). There was a sharp increase in retinopathy prevalence in those with A1C ≥5.5% or FPG ≥5.8 mmol/l. After excluding 144 people using hypoglycemic medication, the change points for the greatest increase in retinopathy prevalence were A1C 5.5% and FPG 7.0 mmol/l. The coefficients of variation were 15.6 for A1C and 28.8 for FPG. Based on the areas under the receiver operating characteristic curves, A1C was a stronger discriminator of retinopathy (0.71 [95% CI 0.66–0.76]) than FPG (0.65 [0.60 – 0.70], P for difference = 0.009). CONCLUSIONS The steepest increase in retinopathy prevalence occurs among individuals with A1C ≥5.5% and FPG ≥5.8 mmol/l. A1C discriminates prevalence of retinopathy better than FPG. Tests of glycemia and their thresholds for diabetes diagnosis is an area of long-standing debate. The presence of diabetic retinopathy is arguably the best criterion from which to compare glycemic measures because it is a specific and early clinical complication usually related to diabetes, and it represents a specific and relevant clinical end point for judging an alternative test (1). For these reasons, diabetic retinopathy has served as the basis for diagnostic criteria of type 2 diabetes (2–4) and provides the rationale for the American Diabetes Association's recommendation of a threshold of a fasting plasma glucose (FPG) of 7.0 mmol/l to define the presence of diabetes (4,5). However, an analysis of three recent population-based cross-sectional studies suggested that there may be considerable variation across populations and that the association of FPG with retinopathy prevalence may be more of a continuous relationship than previously thought (5). A1C levels are being considered as an alternative diagnostic tool for diabetes diagnosis (6). Unlike FPG, A1C does not require an overnight fast, is not affected by short-term lifestyle changes, and has less variability within individuals than FPG (7–9). Nevertheless, few studies have examined the prevalence of retinopathy across the spectrum of A1C levels, which could assist in the designation of ideal A1C diagnostic cut points (2,3). The newly released National Health and Nutrition Examination Survey (NHANES) 2005–2006 incorporated a multiple-field retinal photograph examination, presenting an opportunity to reassess the selection of glucose and A1C cut points for diabetes diagnosis. Our objectives were to examine the relation between levels of A1C and FPG and prevalence of retinopathy in the U.S. population and to compare the ability of both measures to differentiate people with and without retinopathy

    Statistical Communication Theory

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    Contains reports on nine research projects
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