12,403 research outputs found

    The effect of home computer use on children's cognitive and non-cognitive skills

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    In this paper we investigate the effect of using a home computer on children's development. In most OECD countries 70% or more of the households have a computer at home and children use computers quite extensively, even at very young ages. We use data from the Longitudinal Study of Australian Children (LSAC), which follows an Australian cohort born in 1999/2000. Skills and computer usage information is collected when children are approximately 5 and 7 years old. For cognitive skills, our results indicate that computer time has a positive effect. For non-cognitive skills the evidence is mixed, the effect depending on the score and the age of the children. We test the robustness of our results by comparing OLS, IV and Value Added estimators. Generally, the IV estimates are larger and the Value Added estimates lower than the OLS ones. However the pattern of the results is quite consistent. © 2010 Elsevier Ltd. All rights reserved

    Labahitha nom.n., çàìåùàþùåå íàçâàíèå äëÿ Mystes Bristowe, 1938, ñ ïåðåîïèñàíèåì òèïîâîãî âèäà (Aranei: Filistatidae)

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    The monotypic genus Mystes Bristowe, 1938, and its type species, M. oonopiformis Bristowe, 1938, are redescribed based on the neotype male (designated here) and several females. The male is described for the first time and the female endogyne is illustrated for the first time. Morphological analysis reveals that the genus belongs to the Prithinae and is close to the Australian genera Wandella Gray, 1994 and Yardiella Gray, 1994. As the name Mystes is preoccupied by Mystes Champion, 1895 (Coleoptera: Melandryidae), we propose Labahitha nom.n. as a replacement name.Монотипичный род Mystes Bristowe, 1938, и его типовой вид M. oonopiformis Bristowe, 1938 переописываются по обозначенному здесь сам- цу-неотипу и нескольким самкам. Впервые для вида описываются самец и приводятся изображения эн- догины самки. Морфологические признаки этого рода указывают на то, что он принадлежит к под- сем. Prithinae и может быть близкородственным по отношению к Wandella Gray, 1994, и Yardiella Gray, 1994. Так как название Mystes преоккупировано ро- дом Mystes Champion, 1895 (Coleoptera: Melandryidae), мы предлагаем Labahitha nom. n. как замеща- ющее название.Fil: Zonstenin, Sergei L.. Steinhardt Museum Of Natural History, Tel-aviv Universi; IsraelFil: Marusik, Yuri M.. Institute For Biological Problems Of The North; RusiaFil: Fiorini de Magalhaes, Ivan Luiz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentin

    Generation of Noise Time Series with arbitrary Power Spectrum

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    Noise simulation is a very powerful tool in signal analysis helping to foresee the system performance in real experimental situations. Time series generation is however a hard challenge when a robust model of the noise sources is missing. We present here a simple computational technique which allows the generation of noise samples of fixed length, given a desired power spectrum. A few applications of the method are also discussed.Comment: 4 pages, 7 figure

    The B -- TAU FCNC connection in SUSY Unified Theories

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    In the context of SUSY grand unification a link is established between the hadronic and leptonic soft breaking sectors. Such relation is here exploited in particular for FCNC processes in B physics. It is shown how bounds on leptonic FCNC involving the third generation translate into constraints on FC B decays. In the second part of the contribution we show that tests of lepton universality in K and B decays can represent an interesting handle to obtain relevant information on the amount of FCNC in the second and third fermion generation.Comment: 9 pages, 4 figures. Based on talks given at: DIF06, International Workshop on discoveries in flavour physics at e+e- colloders, Laboratori Nazionali di Frascati (Italy), February 28- March 03, 2006; XLIst Rencontres de Moriond, La Thuile, 5-11 March 2006; CORFU2005, Corfu Summer Institute on EPP, Corfu, Greece, September 4-26, 200

    On the existence of 0/1 polytopes with high semidefinite extension complexity

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    In Rothvo\ss{} it was shown that there exists a 0/1 polytope (a polytope whose vertices are in \{0,1\}^{n}) such that any higher-dimensional polytope projecting to it must have 2^{\Omega(n)} facets, i.e., its linear extension complexity is exponential. The question whether there exists a 0/1 polytope with high PSD extension complexity was left open. We answer this question in the affirmative by showing that there is a 0/1 polytope such that any spectrahedron projecting to it must be the intersection of a semidefinite cone of dimension~2^{\Omega(n)} and an affine space. Our proof relies on a new technique to rescale semidefinite factorizations

    A bolometric measurement of the antineutrino mass

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    High statistics calorimetric measurements of the beta spectrum of 187Re are being performed with arrays of silver perrhenate crystals operated at low temperature. After a modification of the experimental set-up, which allowed to substantially reduce the background of spurious counts and therefore to increase the sensitivity on the electron antineutrino mass, a new measurement with 10 silver perrhenate microbolometers is running since July 2002. The crystals have masses between 250 and 350 micrograms and their average FWHM energy resolution, constantly monitored by means of fluorescence X-rays, is of 28.3 eV at the beta end-point. The Kurie plot collected during 4485 hours x mg effective running time has an end-point energy of 2466.1 +/- 0.8{stat} +/- 1.5 {syst} eV, while the half lifetime of the decay is found to be 43.2 +/- 0.2{stat} +/- 0.1{syst} Gy. These values are the most precise obtained so far for 187Re. From the fit of the Kurie plot we can deduce a value for the squared electron antineutrino mass m(nu)^2 of 147 +/- 237{stat} +/- 90{syst} eV^2. The corresponding 90% C.L. upper limit for m(nu) is 21.7 eV.Comment: 3 pages, 3 figures. Submitted to Phys. Rev. Let

    GOLIA: an INTEGRAL archive at INAF-IASF Milano

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    We present the archive of the INTEGRAL data developed and maintained at INAF-IASF Milano. The archive comprises all the public data currently available (revolutions 0026-1079, i.e., December 2002 - August 2011). INTEGRAL data are downloaded from the ISDC Data Centre for Astrophysics, Geneva, on a regular basis as they become public and a customized analysis using the OSA 9.0 software package is routinely performed on the IBIS/ISGRI data. The scientific products include individual pointing images and the associated detected source lists in the 17-30, 30-50, 17-50 and 50-100 keV energy bands, as well as light-curves binned over 100 s in the 17-30 keV band for sources of interest. Dedicated scripts to handle such vast datasets and results have been developed. We make the analysis tools to build such an archive publicly available. The whole database (raw data and products) enables an easy access to the hard X-ray long-term behavior of a large sample of sources.Comment: 10 pages, 7 figures, Accepted for publication in the Astronomy and Computing journa
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