20,462 research outputs found

    Study of muons near shower cores at sea level using the E594 neutrino detector

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    The E594 neutrino detector has been used to study the lateral distribution of muons of energy 3 GeV near shower cores. The detector consists of a 340 ton fine grain calorimeter with 400,000 cells of flash chamber and dimensions of 3.7 m x 20 m x 3.7 m (height). The average density in the calorimeter is 1.4 gm/sq cm, and the average Z is 21. The detector was triggered by four 0.6 sq m scintillators placed immediately on the top of the calorimeter. The trigger required at least two of these four counters. The accompanying extensive air showers (EAS) was sampled by 14 scintillation counters located up to 15 m from the calorimeter. Several off line cuts have been applied to the data. Demanding five particles in at least two of the trigger detectors, a total of 20 particles in all of them together, and an arrival angle for the shower 450 deg reduced the data sample to 11053 events. Of these in 4869 cases, a computer algorithm found at least three muons in the calorimeter

    What is the impact of public care on children's welfare? A review of research findings from England and Wales and their policy implications.

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    The outcomes for children in public care are generally considered to be poor. This has contributed to a focus on reducing the number of children in care: a goal that is made explicit in the provisions of the current Children and Young Persons Bill. Yet while children in care do less well than most children on a range of measures, such comparisons do not disentangle the extent to which these difficulties pre-dated care and the specific impact of care on child welfare. This article explores the specific impact of care through a review of British research since 1991 that provides data on changes in child welfare over time for children in care. Only 12 studies were identified, indicating a lack of research in this important area. The studies consistently found that children entering care tended to have serious problems but that in general their welfare improved over time. This finding is consistent with the international literature. It has important policy implications. Most significantly it suggests that attempts to reduce the use of public care are misguided, and may place more children at risk of serious harm. Instead, it is argued that England and Wales should move toward a Scandinavian system of public care, in which care is seen as a form of family support and is provided for more rather than fewer children and families

    The stationary phase point method for transitional scattering: diffractive radio scintillation for pulsar

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    The stationary phase point (SPP) method in one-dimensional case is introduced to treat the diffractive scintillation. From weak scattering, where the SPP number N=1, to strong scattering (N\gg1), via transitional scattering regime (N\sim2,3), we find that the modulation index of intensity experiences the monotonically increasing from 0 to 1 with the scattering strength, characterized by the ratio of Fresnel scale \rf to diffractive scale \rdiff.Comment: Hanas Meeting paper, appear in ChJAA, 2006, 6, Su

    Coherent Backscattering of Light with Nonlinear Atomic Scatterers

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    We study coherent backscattering of a monochromatic laser by a dilute gas of cold two-level atoms in the weakly nonlinear regime. The nonlinear response of the atoms results in a modification of both the average field propagation (nonlinear refractive index) and the scattering events. Using a perturbative approach, the nonlinear effects arise from inelastic two-photon scattering processes. We present a detailed diagrammatic derivation of the elastic and inelastic components of the backscattering signal both for scalar and vectorial photons. Especially, we show that the coherent backscattering phenomenon originates in some cases from the interference between three different scattering amplitudes. This is in marked contrast with the linear regime where it is due to the interference between two different scattering amplitudes. In particular we show that, if elastically scattered photons are filtered out from the photo-detection signal, the nonlinear backscattering enhancement factor exceeds the linear barrier two, consistently with a three-amplitude interference effect.Comment: 18 pages, 13 figures, submitted to Phys. Rev.

    Radio-wave propagation through a medium containing electron-density fluctuations described by an anisotropic Goldreich-Sridhar spectrum

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    We study the propagation of radio waves through a medium possessing density fluctuations that are elongated along the ambient magnetic field and described by an anisotropic Goldreich-Sridhar power spectrum. We derive general formulas for the wave phase structure function, visibility, angular broadening, diffraction-pattern length scales, and scintillation time scale for arbitrary distributions of turbulence along the line of sight, and specialize these formulas to idealized cases.Comment: 25 pages, 3 figures, submitted to Ap

    Critical Cultural Awareness: Contributions To A Globalizing Psychology

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    The number of psychologists whose work crosses cultural boundaries is increasing. Without a critical awareness of their own cultural grounding, they risk imposing the assumptions, concepts, practices, and values of U.S.-centered psychology on societies where they do not fit, as a brief example from the 2004 Indian Ocean tsunami shows. Hermeneutic thinkers offer theoretical resources for gaining cultural awareness. Culture, in the hermeneutic view, is the constellation of meanings that constitutes a way of life. Such cultural meanings-especially in the form of folk psychologies and moral visions-inevitably shape every psychology, including U.S. psychology. The insights of hermeneutics, as well as its conceptual resources and research approaches, open the way for psychological knowledge and practice that are more culturally situated

    Missing and Quenched Gamow Teller Strength

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    Gamow-Teller strength functions in full (pf)8(pf)^{8} spaces are calculated with sufficient accuracy to ensure that all the states in the resonance region have been populated. Many of the resulting peaks are weak enough to become unobservable. The quenching factor necessary to bring into agreement the low lying observed states with shell model predictions is shown to be due to nuclear correlations. To within experimental uncertainties it is the same that is found in one particle transfer and (e,e') reactions. Perfect consistency between the observed 48Ca(p,n)48Sc^{48}Ca(p,n)^{48}Sc peaks and the calculation is achieved by assuming an observation threshold of 0.75\% of the total strength, a value that seems typical in several experimentsComment: 11 pages, 6 figures avalaible upon request, RevTeX, FTUAM-94/0

    Observation of magnetocoriolis waves in a liquid metal Taylor-Couette experiment

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    The first observation of fast and slow magnetocoriolis (MC) waves in a laboratory experiment is reported. Rotating nonaxisymmetric modes arising from a magnetized turbulent Taylor-Couette flow of liquid metal are identified as the fast and slow MC waves by the dependence of the rotation frequency on the applied field strength. The observed slow MC wave is damped but the observation provides a means for predicting the onset of the Magnetorotational Instability
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