3,014 research outputs found

    Muon Spectra of Quasi-Elastic and 1-Pion Production Events in LBL Neutrino Oscillation Experiments

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    The muon energy spectra of the quasi-elastic and 1-pion production events in a LBL experiment, like K2K, are predicted to follow closely the neutrino energy spectrum, with downward shifts of the energy scale by /2M/2 M and (+MΔ2−M2)/2M( + M_\Delta^2 - M^2)/2 M respectively. These predictions seem to agree with the observed muon spectra in the K2K nearby detector. The corresponding muon spectra in the far-away (SK) detector are predicted to show characteristic spectral distortions induced by νμ\nu_\mu oscillation. Comparison of the predicted spectral distortions with the observed muon spectra of the 1-Ring and 2-Ring muon events in the SK detector will help to determine the oscillation parameters. The results will be applicable to other LBL experiments as well.Comment: 13 pages. One figure and a few comments added, final version to appear in P

    GEM Operation in Negative Ion Drift Gas Mixtures

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    The first operation of GEM gas gain elements in negative ion gas mixtures is reported. Gains up to several thousand were obtained from single-stage GEMs in carbon disulfide vapor at low pressure, and in mixtures of carbon disulfide with Argon and Helium, some near 1 bar total pressure.Comment: 7 pages, 3 figure

    Twenty-Five Year Secular Trends in Lipids and Modifiable Risk Factors in a Population-Based Biracial Cohort: The Coronary Artery Risk Development in Young Adults (CARDIA) Study, 1985-2011

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    BACKGROUND: Cross-sectional analyses suggest that total and low-density lipoprotein cholesterol (LDL-c) trends that had been declining are now reversing. We examined longitudinal data from the Coronary Artery Risk Development in Young Adults (CARDIA) study to examine secular trends in total cholesterol, LDL-c, high-density lipoprotein cholesterol (HDL-c), and triglycerides over 25 years. We also assessed whether modifiable lifestyle factors (body mass index, physical activity, alcohol consumption, smoking, and lipid-lowering medications) are associated with these trends. METHODS AND RESULTS: CARDIA recruited 5115 black and white men and women ages 18 to 30 years from 4 US communities in 1985-1986, and re-examined them 5, 10, 15, 20, and 25 years later. Secular trends, modeled as age-matched time trends, were estimated using repeated-measures regression stratified on race and sex. Total cholesterol and LDL-c initially decreased approximately 5 to 8 mg/dL between visits before plateauing and moving toward adverse trends in all groups, except black women, by year 25. HDL-c showed an upward secular trend of 1 to 3 mg/dL between visits starting at year 15 in all groups; triglyceride trends were largely flat. Obesity and use of lipid-lowering medications, which both increased over follow-up, had strong independent, but opposite, associations with lipid trends over time. In aggregate, associations of modifiable lifestyle factors counterbalanced one another, minimally influencing secular trends. CONCLUSIONS: Over 25 years, initially favorable trends in total cholesterol and LDL-c have leveled off and may be reversing, persisting after control for modifiable risk factors. Factors such as dietary changes over 25 years and poor adherence to medications are candidates for additional investigation

    Variable-Speed Induction Motor Drives for Aircraft Environmental Control Compressors

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    New, more-efficient designs for aircraft jet engines are not capable of supplying the large quantities of bleed air necessary to provide pressurization and air conditioning for the environmental control systems (ECS) of the next generation of large passenger aircraft. System analysis and engineering have determined that electrically-driven ECS can help to maintain the improved fuel efficiencies; and electronic controllers and induction motors are now being developed in a NASA/NPD SBIR Program to drive both types of ECS compressors. Previous variable-speed induction motor/controller system developments and publications have primarily focused on field-oriented control, with large transient reserve power, for maximum acceleration and optimum response in actuator and robotics systems. The application area addressed herein is characterized by slowly-changing inputs and outputs, small reserve power capability for acceleration, and optimization for maximum efficiency. This paper therefore focuses on the differences between this case and the optimum response case, and shows the development of this new motor/controller approach. It starts with the creation of a new set of controller requirements. In response to those requirements, new control algorithms are being developed and implemented in an embedded computer, which is integrated into the motor controller closed loop. Buffered logic outputs are used to drive the power switches in a resonant-technology, power processor/motor-controller, at switching/resonant frequencies high enough to support efficient high-frequency induction motor operation at speeds up to 50,000-RP

    Catalogue of new Herbig Ae/Be and classical Be stars - A machine learning approach to Gaia DR2

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    Context. The intermediate-mass pre-main sequence Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low- and high-mass stars. The study of the general properties of these objects is hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources are known. Aims. Our goal is to identify new Herbig Ae/Be candidates to create a homogeneous and well defined catalogue of these objects. Methods. We have applied machine learning techniques to 4 150 983 sources with data from Gaia DR2, 2MASS, WISE, and IPHAS or VPHAS+. Several observables were chosen to identify new Herbig Ae/Be candidates based on our current knowledge of this class, which is characterised by infrared excesses, photometric variabilities, and Hα emission lines. Classical techniques are not efficient for identifying new Herbig Ae/Be stars mainly because of their similarity with classical Be stars, with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified new classical Be stars. Results. We have obtained a large catalogue of 8470 new pre-main sequence candidates and another catalogue of 693 new classical Be candidates with a completeness of 78.8 ± 1.4% and 85.5 ± 1.2%, respectively. Of the catalogue of pre-main sequence candidates, at least 1361 sources are potentially new Herbig Ae/Be candidates according to their position in the Hertzsprung-Russell diagram. In this study we present the methodology used, evaluate the quality of the catalogues, and perform an analysis of their flaws and biases. For this assessment, we make use of observables that have not been accounted for by the algorithm and hence are selection-independent, such as coordinates and parallax based distances. The catalogue of new Herbig Ae/Be stars that we present here increases the number of known objects of the class by an order of magnitude

    Multianalytical study of patina formed on archaeological metal objects from Bliesbruck-Reinheim

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    Patinas naturally formed on archaeological bronze alloys were characterized using light microscopy (LM), micro energy dispersive X-ray fluorescence analysis (mu-EDXRF), time of flight secondary ion mass spectrometry (TOF-SIMS) and scanning electron microscopy in combination with energy dispersive X-ray microanalysis (SEM/EDX). The examinations carried out on cross-sections of samples have shown that in all samples the copper content in the corrosion layer is lower than in the bulk, while an increase of tin and lead could be observed. Two different types of corrosion were found: first type, a corrosion formation leading to a three layer structure was observed on lead bronze. The outer layer consists mainly of Cu(II) compounds and soil material, followed by a fragmented layer of cuprous oxide and the surface layer of the alloy, where a depletion of copper and an enrichment of tin and high amounts of Cl could be detected, The second type of corrosion is characterized by a two layer structure on the tin bronze sample consisting of an outer layer with copper containing corrosion products and a layer with cracks, which reveals a depletion of copper whereas tin and lead are enriched. Also high amounts of Si were detected in this surface layer

    Accelerated aging: A marker for social factors resulting in cardiovascular events?

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    Background: Medicine and public health are shifting away from a purely personal responsibility model of cardiovascular disease (CVD) prevention towards a societal view targeting social and environmental conditions and how these result in disease. Given the strong association between social conditions and CVD outcomes, we hypothesize that accelerated aging, measuring earlier health decline associated with chronological aging through a combination of biomarkers, may be a marker for the association between social conditions and CVD. Methods: We used data from the Coronary Artery Risk Development in Young Adults study (CARDIA). Accelerated aging was defined as the difference between biological and chronological age. Biological age was derived as a combination of 7 biomarkers (total cholesterol, HDL, glucose, BMI, CRP, FEV1/h(2), MAP), representing the physiological effect of wear and tear usually associated with chronological aging. We studied accelerated aging measured in 2005-06 as a mediator of the association between social factors measured in 2000-01 and 1) any incident CVD event; 2) stroke; and 3) all-cause mortality occurring from 2007 through 18. Results: Among 2978 middle-aged participants, mean (SD) accelerated aging was 3.6 (11.6) years, i.e., the CARDIA cohort appeared to be, on average, 3 years older than its chronological age. Accelerated aging partially mediated the association between social factors and CVD (N=219), stroke (N=36), and mortality (N=59). Accelerated aging mediated 41% of the total effects of racial discrimination on stroke after adjustment for covariates. Accelerated aging also mediated other relationships but to lesser degrees. Conclusion: We provide new evidence that accelerated aging based on easily measurable biomarkers may be a viable marker to partially explain how social factors can lead to cardiovascular outcomes and death
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