3,195 research outputs found

    The A&A Experience With Impact Factors

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    There is a widespread impression that the scientific journal "Astronomy & Astrophysics" (A&A) has a smaller impact, as measured by citations to articles, than some of the other major astronomy journals. This impression was apparently supported - and probably created - by the Journal Citation Report (JCR), which is prepared annually by the Institute of Scientific Information (ISI) Web of Knowledge. The published poor impact factor of A&A was in fact wrong and was due to a serious flaw in the method used by ISI Web of Knowledge to determine it. The resulting damage inflicted upon A&A by the JCR is incalculable.Comment: 4 pages, to be published in A. Heck (ed.) "Organizations and Strategies in Astronomy, Vol. 5" (Kluwer, 2004

    A Novel Adaptive Spectrum Noise Cancellation Approach for Enhancing Heartbeat Rate Monitoring in a Wearable Device

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    This paper presents a novel approach, Adaptive Spectrum Noise Cancellation (ASNC), for motion artifacts removal in Photoplethysmography (PPG) signals measured by an optical biosensor to obtain clean PPG waveforms for heartbeat rate calculation. One challenge faced by this optical sensing method is the inevitable noise induced by movement when the user is in motion, especially when the motion frequency is very close to the target heartbeat rate. The proposed ASNC utilizes the onboard accelerometer and gyroscope sensors to detect and remove the artifacts adaptively, thus obtaining accurate heartbeat rate measurement while in motion. The ASNC algorithm makes use of a commonly accepted spectrum analysis approaches in medical digital signal processing, discrete cosine transform, to carry out frequency domain analysis. Results obtained by the proposed ASNC have been compared to the classic algorithms, the adaptive threshold peak detection and adaptive noise cancellation. The mean (standard deviation) absolute error and mean relative error of heartbeat rate calculated by ASNC is 0.33 (0.57) beats·min-1 and 0.65%, by adaptive threshold peak detection algorithm is 2.29 (2.21) beats·min-1 and 8.38%, by adaptive noise cancellation algorithm is 1.70 (1.50) beats·min-1 and 2.02%. While all algorithms performed well with both simulated PPG data and clean PPG data collected from our Verity device in situations free of motion artifacts, ASNC provided better accuracy when motion artifacts increase, especially when motion frequency is very close to the heartbeat rate

    The Origin of the Exoplanets

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    We explore two ways in which objects of planetary masses can form. One is in disk systems like the solar system. The other is in dense clusters where stars and brown dwarfs form. We do not yet have the instrumental accuracy to detect multiplanet systems with masses like those in solar system; with our present technology from a distant site, only the effects of Jupiter could be detected. We show that the orbital characteristics (eccentricities and semimajor axes) of stellar, brown dwarf, and exoplanet companions of solar-type stars are all the same within our measuring accuracies and are very different than the planets in the solar system. The period ratios in multiplanet systems do not distinguish between the two models. We conclude that most of the exoplanets found to date are formed like stellar companions and not in disk systems like the solar system. This conclusion explains why metal-poor stars lack planets: because metal-poor stars lack stellar companions with short periods. The distribution of exoplanetary periods for primaries having [Fe/H]< -0.3 fits the distribution for stellar companions of metal-poor stars and not of metal-rich stars

    Reflections on Mark W. Allam....

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    Pulse shape simulation for segmented true-coaxial HPGe detectors

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    A new package to simulate the formation of electrical pulses in segmented true-coaxial high purity germanium detectors is presented. The computation of the electric field and weighting potentials inside the detector as well as of the trajectories of the charge carriers is described. In addition, the treatment of bandwidth limitations and noise are discussed. Comparison of simulated to measured pulses, obtained from an 18-fold segmented detector operated inside a cryogenic test facility, are presented.Comment: 20 pages, 16 figure

    Identification of photons in double beta-decay experiments using segmented germanium detectors - studies with a GERDA Phase II prototype detector

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    The sensitivity of experiments searching for neutrinoless double beta-decay of germanium was so far limited by the background induced by external gamma-radiation. Segmented germanium detectors can be used to identify photons and thus reduce this background component. The GERmanium Detector Array, GERDA, will use highly segmented germanium detectors in its second phase. The identification of photonic events is investigated using a prototype detector. The results are compared with Monte Carlo data.Comment: 20 pages, 7 figures, to be submitted to NIM-

    Axes determination for segmented true-coaxial HPGe detectors

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    A fast method to determine the crystallographic axes of segmented true-coaxial high-purity germanium detectors is presented. It is based on the analysis of segment-occupancy patterns obtained by irradiation with radioactive sources. The measured patterns are compared to predictions for different axes orientations. The predictions require a simulation of the trajectories of the charge carriers taking the transverse anisotropy of their drift into account.Comment: 18 pages, 1 table, 31 figures; included background contribution to the occupancy patterns and systematic uncertainties, results slightly change

    Diffractive Meson Production and the Quark-Pomeron Coupling

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    Diffractive meson production at HERA offers interesting possibilities to investigate diffractive processes and thus to learn something about the properties of the pomeron. The most succesful phenomenological description of the pomeron so far assumes it to couple like a C=+1C = +1 isoscalar photon to single quarks. This coupling leads, however, to problems for exclusive diffractive reactions. We propose a new phenomenological pomeron vertex, which leads to very good fits to the known data, but avoids the problems of the old vertex.Comment: 20 pages, latex with uuencoded postscript, revised versio

    The dose-response relationship between training load and aerobic fitness in academy rugby union players

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    © 2018 Human Kinetics, Inc. Purpose: To identify the dose-response relationship between measures of training load (TL) and changes in aerobic fitness in academy rugby union players. Method: Training data from 10 academy rugby union players were collected during a 6-wk in-season period. Participants completed a lactate-threshold test that was used to assess VO 2 max, velocity at VO 2 max, velocity at 2 mmol/L (lactate threshold), and velocity at 4 mmol/L (onset of lactate accumulation; vOBLA) as measures of aerobic fitness. Internal-TL measures calculated were Banister training impulse (bTRIMP), Edwards TRIMP, Lucia TRIMP, individualized TRIMP (iTRIMP), and session RPE (sRPE). External-TL measures calculated were total distance, PlayerLoad™, high-speed distance > 15 km/h, very-high-speed distance > 18 km/h, and individualized high-speed distance based on each player’s vOBLA. Results: A second-order-regression (quadratic) analysis found that bTRIMP (R 2 = .78, P = .005) explained 78% of the variance and iTRIMP (R 2 = .55, P = .063) explained 55% of the variance in changes in VO 2 max. All other HR-based internal-TL measures and sRPE explained less than 40% of variance with fitness changes. External TL explained less than 42% of variance with fitness changes. Conclusions: In rugby players, bTRIMP and iTRIMP display a curvilinear dose-response relationship with changes in maximal aerobic fitness
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