707 research outputs found

    Estimate of confidence in paleomagnetic directions derived from mixed remagnetization circle and direct observational data

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    A method is presented for obtaining the direction and confidence oval for a paleomagnetic component at a site given a number of independently oriented samples, some of which give an estimate of the remanence direction, while others yield only remagnetization circles. Such mixed remagnetization circle-remanence direction data frequently characterise paleomagnetic sites carrying two remanence components where the component of interest is small and less dispersed compared to a more easily removed one. The method described maximises the amount of usable data per site and thus leads to an improved site direction estimate.           ARK: https://n2t.net/ark:/88439/y000446 Permalink: https://geophysicsjournal.com/article/149 &nbsp

    Application of Bounded Linear Stability Analysis Method for Metrics-Driven Adaptive Control

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    This paper presents the application of Bounded Linear Stability Analysis (BLSA) method for metrics-driven adaptive control. The bounded linear stability analysis method is used for analyzing stability of adaptive control models, without linearizing the adaptive laws. Metrics-driven adaptive control introduces a notion that adaptation should be driven by some stability metrics to achieve robustness. By the application of bounded linear stability analysis method the adaptive gain is adjusted during the adaptation in order to meet certain phase margin requirements. Analysis of metrics-driven adaptive control is evaluated for a second order system that represents a pitch attitude control of a generic transport aircraft. The analysis shows that the system with the metrics-conforming variable adaptive gain becomes more robust to unmodeled dynamics or time delay. The effect of analysis time-window for BLSA is also evaluated in order to meet the stability margin criteria

    Monkey-based Research on Human Disease: The Implications of Genetic Differences

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    Assertions that the use of monkeys to investigate human diseases is valid scientifically are frequently based on a reported 90–93% genetic similarity between the species. Critical analyses of the relevance of monkey studies to human biology, however, indicate that this genetic similarity does not result in sufficient physiological similarity for monkeys to constitute good models for research, and that monkey data do not translate well to progress in clinical practice for humans. Salient examples include the failure of new drugs in clinical trials, the highly different infectivity and pathology of SIV/HIV, and poor extrapolation of research on Alzheimer’s disease, Parkinson’s disease and stroke. The major molecular differences underlying these inter-species phenotypic disparities have been revealed by comparative genomics and molecular biology — there are key differences in all aspects of gene expression and protein function, from chromosome and chromatin structure to post-translational modification. The collective effects of these differences are striking, extensive and widespread, and they show that the superficial similarity between human and monkey genetic sequences is of little benefit for biomedical research. The extrapolation of biomedical data from monkeys to humans is therefore highly unreliable, and the use of monkeys must be considered of questionable value, particularly given the breadth and potential of alternative methods of enquiry that are currently available to scientists

    On the accretion disc properties in eclipsing dwarf nova EM Cyg

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    In this paper we analyzed the behavior of the unusual dwarf nova EM Cyg using the data obtained in April-October, 2007 in Vyhorlat observatory (Slovak Republic) and in September, 2006 in Crimean Astrophysical Observatory (Ukraine). During our observations EM Cyg has shown outbursts in every 15-40 days. Because on the light curves of EM Cyg the partial eclipse of an accretion disc is observed we applied the eclipse mapping technique to reconstruct the temperature distribution in eclipsed parts of the disc. Calculations of the accretion rate in the system were made for the quiescent and the outburst states of activity for different distances.Comment: 6 pages, 3 figures, accepted in Astrophysics and Space Scienc

    International Trade and Investment Sanctions

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    The purpose of this paper is to clarify the theory of international economic sanctions and to provide estimates of the short-run economic impact on South Africa of externally imposed reductions of the imports and capital flows into that country. A macroeconomic picture of South Africa's "dependence" is drawn, and the economy's vulnerability in the short run is seen to be in its capacity to import, not in exports or capital flows. Trade and capital sanctions most clearly damage South Afnca's growth potential; the short-run impact is harder to quantify. A static linear programming model of the South African economy is constructed in an attempt at this quantification. This model estimates that small sanctions would have small impact—i.e., if imports were reduced by less than one-fourth, GDP would be cut by only about one half as large a percentage as imports. Larger import reductions cause greater damage. If imports were to be cut in half, not only would GDP be seriously reduced but massive unemployment and relocation of white labor would occur.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68182/2/10.1177_002200277902300401.pd

    The Supernovae Integral Field Spectrograph: keys to high-precision spectro-photometry

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    The Supernovae Integral Field Spectrograph: keys to a better spectro-photometry The Nearby Supernova Factory aims at discovering and observing a sample of type Ia supernovae through the dedicated Supernovae Integral Field Spectrograph, currently in operation since 2004 on Mauna-Kea UH telescope. To reach the targeted spectro-photometric accuracy, attention has been focused on various aspects of the calibration procedure, including: estimate of the night photometricity, derivation of the mean atmospheric extinction over the extended optical domain (320-1000 nm), its modeling in terms of physical components (Rayleigh and aerosol scatterings, ozone absorption and telluric lines) and its variability within a given night. Point-source extraction from the IFS datacube also requires a detailed knowledge of the atmospheric-induced point spread function (PSF). The overall accuracy of the calibration chain is estimated on reference flux standard stars

    Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

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    We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

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    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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