1,957 research outputs found

    Improved search for galactic white dwarf binaries in Mock LISA Data Challenge 1B using an F-statistic template bank

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    We report on our F-statistic search for white-dwarf binary signals in the Mock LISA Data Challenge 1B (MLDC1B). We focus in particular on the improvements in our search pipeline since MLDC1, namely refinements in the search pipeline and the use of a more accurate detector response (rigid adiabatic approximation). The search method employs a hierarchical template-grid based exploration of the parameter space, using a coincidence step to distinguish between primary (``true'') and secondary maxima, followed by a final (multi-TDI) ``zoom'' stage to provide an accurate parameter estimation of the final candidates.Comment: 11 pages, 4 included figures, submitted to Classical and Quantum Gravity for GWDAW12 proceeding

    Searching for Galactic White Dwarf Binaries in Mock LISA Data using an F-Statistic Template Bank

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    We describe an F-statistic search for continuous gravitational waves from galactic white-dwarf binaries in simulated LISA Data. Our search method employs a hierarchical template-grid based exploration of the parameter space. In the first stage, candidate sources are identified in searches using different simulated laser signal combinations (known as TDI variables). Since each source generates a primary maximum near its true "Doppler parameters" (intrinsic frequency and sky position) as well as numerous secondary maxima of the F-statistic in Doppler parameter space, a search for multiple sources needs to distinguish between true signals and secondary maxima associated with other, "louder" signals. Our method does this by applying a coincidence test to reject candidates which are not found at nearby parameter space positions in searches using each of the three TDI variables. For signals surviving the coincidence test, we perform a fully coherent search over a refined parameter grid to provide an accurate parameter estimation for the final candidates. Suitably tuned, the pipeline is able to extract 1989 true signals with only 5 false alarms. The use of the rigid adiabatic approximation allows recovery of signal parameters with errors comparable to statistical expectations, although there is still some systematic excess with respect to statistical errors expected from Gaussian noise. An experimental iterative pipeline with seven rounds of signal subtraction and re-analysis of the residuals allows us to increase the number of signals recovered to a total of 3419 with 29 false alarms.Comment: 29 pages, 11 figures; submitted to Classical and Quantum Gravit

    Sensory and chemical evaluation of laboratory ensiled hybrid Napier grass prepared using Lactobacillus plantarum and propionic acid as additives

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    The present study was undertaken to evaluate silage made from hybrid Napier grass (Pennisetum purpureum) ensiled in the laboratory using various additives with regard to sensory as well as chemical characteristics. Four different silages were prepared viz., grass ensiled without additives (GS) as control, and grass silage with Lactobacillus plantarum at 1 x 105 CFU per gram of fresh forage (GSL), grass silage with propionic acid at the rate 0.45 kg per ton of fodder (GSA), and grass silage with combination of Lactobacillus plantarum (1 x 105 CFU per gram of fresh forage) and propionic acid (0.45 kg per ton of fodder) (GSLA) in triplicates. One from each triplicate was opened on 21, 30 and 45 days of ensiling and was evaluated for sensory (colour, aroma, presence or absence of extraneous matter) and chemical (pH, lactic acid, proximate analysis and fibre fractions) characteristics. From the overall results, it could be concluded that hybrid Napier grass, ensiled for 21 days using L. plantarum was effective in preserving its nutritive value

    Abattoir sludge and food waste combination as a feed source for black soldier fly larvae: Optimisation of level of larval incorporation in the substrate

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    The study was conducted to optimize the level of Black Soldier Fly Larvae (BSFL) incorporation in the abattoir sludge and food waste combination. The substrate for the study included a combination of 70 per cent abattoir sludge as the principal substrate (PS) and 30 per cent hostel food waste as the co-substrate (Co- S) for BSFL rearing. Experiments were carried out to fix the level of larval incorporation into 320 g of the substrate and to assess the nutritional qualities of the harvested prepupae. The BSFL were incorporated in four different levels in 320 g of substrate (T1: 150 mg larvae, T2: 450 mg larvae, T3:600 mg larvae and T4: 750 mg larvae). The efficiency of BSFL to feed on the substrate and get converted into biomass was evaluated for the treatment combinations. Among the different treatments, T1had significantly (p<0.001) higher mean prepupal weight and larval survivability. Hence the addition of 150 mg larvae to the 320 g of substrate was found to be optimum for BSFL biomass production

    The Murchison Widefield Array: Design Overview

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    The Murchison Widefield Array (MWA) is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations, but is initially focused on three key science projects. These are detection and characterization of 3-dimensional brightness temperature fluctuations in the 21cm line of neutral hydrogen during the Epoch of Reionization (EoR) at redshifts from 6 to 10, solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources,and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broad-band active dipoles, arranged into 512 tiles comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5km in diameter, with a small number of outliers extending to 3km. All tile-tile baselines are correlated in custom FPGA-based hardware, yielding a Nyquist-sampled instantaneous monochromatic uv coverage and unprecedented point spread function (PSF) quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment,allowing full exploitation of the instrumental capabilities.Comment: 9 pages, 5 figures, 1 table. Accepted for publication in Proceedings of the IEE

    The association of circulating amylin with β-amyloid in familial Alzheimer's disease.

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    Introduction: This study assessed the hypothesis that circulating human amylin (amyloid-forming) cross-seeds with amyloid beta (Aβ) in early Alzheimer's disease (AD). Methods: Evidence of amylin-AD pathology interaction was tested in brains of 31 familial AD mutation carriers and 20 cognitively unaffected individuals, in cerebrospinal fluid (CSF) (98 diseased and 117 control samples) and in genetic databases. For functional testing, we genetically manipulated amylin secretion in APP/PS1 and non-APP/PS1 rats. Results: Amylin-Aβ cross-seeding was identified in AD brains. High CSF amylin levels were associated with decreased CSF Aβ42 concentrations. AD risk and amylin gene are not correlated. Suppressed amylin secretion protected APP/PS1 rats against AD-associated effects. In contrast, hypersecretion or intravenous injection of human amylin in APP/PS1 rats exacerbated AD-like pathology through disruption of CSF-brain Aβ exchange and amylin-Aβ cross-seeding. Discussion: These findings strengthened the hypothesis of circulating amylin-AD interaction and suggest that modulation of blood amylin levels may alter Aβ-related pathology/symptoms

    Psychosocial Assessment of Candidates for Transplantation (PACT) Score Identifies High Risk Patients in Pediatric Renal Transplantation

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    Background: Currently, there is no standardized approach for determining psychosocial readiness in pediatric transplantation. We examined the utility of the Psychosocial Assessment of Candidates for Transplantation (PACT) to identify pediatric kidney transplant recipients at risk for adverse clinical outcomes.Methods: Kidney transplant patients &lt;21-years-old transplanted at Duke University Medical Center between 2005 and 2015 underwent psychosocial assessment by a social worker with either PACT or unstructured interview, which were used to determine transplant candidacy. PACT assessed candidates on a scale of 0 (poor candidate) to 4 (excellent candidate) in areas of social support, psychological health, lifestyle factors, and understanding. Demographics and clinical outcomes were analyzed by presence or absence of PACT and further characterized by high (≥3) and low (≤2) scores.Results: Of 54 pediatric patients, 25 (46.3%) patients underwent pre-transplant evaluation utilizing PACT, while 29 (53.7%) were not evaluated with PACT. Patients assessed with PACT had a significantly lower percentage of acute rejection (16.0 vs. 55.2%, p = 0.007). After adjusting for HLA mismatch, a pre-transplant PACT score was persistently associated with lower odds of acute rejection (Odds Ratio 0.119, 95% Confidence Interval 0.027–0.52, p = 0.005). In PACT subsection analysis, the lack of family availability (OR 0.08, 95% CI 0.01–0.97, p = 0.047) and risk for psychopathology (OR 0.34, 95% CI 0.13–0.87, p = 0.025) were associated with a low PACT score and post-transplant non-adherence.Conclusions: Our study highlights the importance of standardized psychosocial assessments and the potential use of PACT in risk stratifying pre-transplant candidates
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