1,048 research outputs found

    The efficiency factorization multiplier for the Watson efficiency in partitioned linear models: some examples and a literature review

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    We consider partitioned linear models where the model matrix X = (X1 : X2) has full column rank, and concentrate on the special case whereX0 1X2 = 0 when we say that the model is orthogonally partitioned. We assume that the underlying covariance matrix is positive definite and introduce the efficiency factorization multiplier which relates the total Watson efficiency of ordinary least squares to the product of the two subset Watson efficiencies. We illustrate our findings with several examples and present a literature review

    Measurements of sound-speed and density contrasts of zooplankton in Antarctic waters

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    Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in ICES Journal of Marine Science 62 (2005): 818-831, doi:10.1016/j.icesjms.2004.12.020.Sound-speed and density contrasts (h and g, respectively), two important acoustic material properties, of live zooplankton were measured off the western Antarctic Peninsula during a Southern Ocean GLOBEC cruise conducted from 9 April to 21 May 2002. The work included in situ sound-speed contrast and shipboard density-contrast measurements. The temperature and pressure (depth) dependence of the sound-speed contrast of Euphausia superba and E. crystallorophias as well as that of some other zooplankton species were investigated. The size range of E. superba used in the measurements varied from about 20 mm to 57 mm, with mean length of 36.7 mm and standard deviation of 9.8 mm, which covered life stages from juvenile to adult. For E. superba, there was no statistically significant depth dependence, but there was a moderate dependence of sound-speed and density contrasts on the size of the animals. The measured sound-speed contrast varied between 1.018 and 1.044, with mean value 1.0279 and standard deviation 0.0084, while the measured density contrast varied between 1.007 and 1.036, with mean value 1.0241 and standard deviation 0.0082. For E. crystallorophias and Calanus there was a measurable depth dependence in sound-speed contrast. The in situ sound-speed contrasts for E. crystallorophias were 1.025 ± 0.004 to 1.029 ± 0.009. For Calanus, they were variable, with one set giving a value of 0.949 ± 0.001 and the other giving 1.013 ± 0.002. Shipboard measurements of other taxa/species also showed substantial variation in g and h. In general, values of g ranged from 0.9402 to 1.051 and h ranged from 0.949 to 1.096. The variation of the material properties is related to species, type, size, stage, and in some cases depth of occurrence. The uncertainty of the estimates of zooplankton biomass attributable to these variations in g and h can be quite large (more than 100 fold). Improvements in making biological inferences from acoustic data depend strongly on increased information about the material properties of zooplankton and the biological causes for their variation, as well as a knowledge of the species composition and abundance.This work was supported by the National Science Foundation, grant No. OPP 0125629

    Scaling tests of the improved Kogut-Susskind quark action

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    Improved lattice actions for Kogut-Susskind quarks have been shown to improve rotational symmetry and flavor symmetry. In this work we find improved scaling behavior of the rho and nucleon masses expressed in units of a length scale obtained from the static quark potential, and better behavior of the Dirac operator in instanton backgrounds.Comment: 4 pages, 4 figures, Revte

    The effects of the bacterial interaction with visible-light responsive titania photocatalyst on the bactericidal performance

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    Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2

    Predictive ability of logistic regression, auto-logistic regression and neural network models in empirical land-use change modeling: a case study

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    The objective of this study is to compare the abilities of logistic, auto-logistic and artificial neural network (ANN) models for quantifying the relationships between land uses and their drivers. In addition, the application of the results obtained by the three techniques is tested in a dynamic land-use change model (CLUE-s) for the Paochiao watershed region in Taiwan. Relative operating characteristic curves (ROCs), kappa statistics, multiple resolution validation and landscape metrics were used to assess the ability of the three techniques in estimating the relationship between driving factors and land use and its subsequent application in land-use change models. The validation results illustrate that for this case study ANNs constitute a powerful alternative for the use of logistic regression in empirical modeling of spatial land-use change processes. ANNs provide in this case a better fit between driving factors and land-use pattern. In addition, auto-logistic regression performs better than logistic regression and nearly as well as ANNs. Auto-logistic regression and ANNs are considered especially useful when the performance of more conventional models is not satisfactory or the underlying data relationships are unknown. The results indicate that an evaluation of alternative techniques to specify relationships between driving factors and land use can improve the performance of land-use change models

    Temporal structure of stimulated-Brillouin-scattering reflectivity considering transversal-mode development

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    The time-resolved reflectivity of optical phase conjugation by stimulated Brillouin scattering ~SBS! is investigated both theoretically and experimentally. A three-dimensional and transient model of SBS is developed to compare the experimental and theoretical results. Noise initiation of the SBS process is included in the model to simulate the shot-to-shot variation in the reflectivity and the Stokes temporal profile.Shahraam Afshaarvahid, Axel Heuer, Ralf Menzel, and Jesper Munc

    An Alternative Method to Deduce Bubble Dynamics in Single Bubble Sonoluminescence Experiments

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    In this paper we present an experimental approach that allows to deduce the important dynamical parameters of single sonoluminescing bubbles (pressure amplitude, ambient radius, radius-time curve) The technique is based on a few previously confirmed theoretical assumptions and requires the knowledge of quantities such as the amplitude of the electric excitation and the phase of the flashes in the acoustic period. These quantities are easily measurable by a digital oscilloscope, avoiding the cost of expensive lasers, or ultrafast cameras of previous methods. We show the technique on a particular example and compare the results with conventional Mie scattering. We find that within the experimental uncertainties these two techniques provide similar results.Comment: 8 pages, 5 figures, submitted to Phys. Rev.

    Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of s√=7TeV proton-proton collisions

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    Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson
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