23,305 research outputs found

    The development of complex verb constructions in British Sign Language

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    This study focuses on the mapping of events onto verb-argument structures in British Sign Language (BSL). The development of complex sentences in BSL is described in a group of 30 children, aged 3;2–12;0, using data from comprehension measures and elicited sentence production. The findings support two interpretations: firstly, in the mapping of concepts onto language, children acquiring BSL overgeneralize the use of argument structure related to perspective shifting;secondly, these overgeneralizations are predicted by the typological characteristics of the language and modality. Children under age 6;0, in attempting to produce sentences encoded through a perspective shift, begin by breaking down double-verb constructions (AB verbs) into components, producing only the part of the verb phrase which describes the perspective of the patient. There is also a prolonged period of development of non-manual features, with the full structure not seen in its adult form until after 9;0. The errors in the use of AB verbs and the subsequent protracted development of correct usage are explained in terms of the conceptual–linguistic interface

    An Investigation of AdS2_2 Backreaction and Holography

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    We investigate a dilaton gravity model in AdS2_2 proposed by Almheiri and Polchinski and develop a 1d effective description in terms of a dynamical boundary time with a Schwarzian derivative action. We show that the effective model is equivalent to a 1d version of Liouville theory, and investigate its dynamics and symmetries via a standard canonical framework. We include the coupling to arbitrary conformal matter and analyze the effective action in the presence of possible sources. We compute commutators of local operators at large time separation, and match the result with the time shift due to a gravitational shockwave interaction. We study a black hole evaporation process and comment on the role of entropy in this model.Comment: 32 pages, 6 figures, v3: typos corrected and references added, matches published versio

    Smarter Programming of the Female Condom: Increasing Its Impact on HIV Prevention in the Developing World

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    The purpose of this study was to investigate the relative value of the female condom for HIV prevention within heterosexual relationships in the developing world. In the last ten years, the world has witnessed both historic financial commitments to HIV/AIDS and new prevention options, including biomedical prevention research, male circumcision, and a dramatic scale-up of voluntary counseling and testing. At the same time, where HIV remains at epidemic levels in many countries, there has been a growing commitment to treatment access alongside prevention programs. However, portions of populations, particularly youth and women, remain highly vulnerable to HIV infection. Accordingly, the global health community can benefit from a better understanding of how existing prevention options should be effectively and efficiently delivered to reduce HIV in the developing world. This report provides guidance for the global health community for considering how the female condom fits within the set of prevention interventions currently available

    Superconducting spin precession magnets for a new neutron spectrometer

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    The required field shape of optimal Larmor precession magnets to obtain the bestpossible homogeneity is B0cos2(¿z/L). In practice this field shape is approximated by 30 superimposed concentric solenoids. The coils are made with an extreme dimensional precision with a typical error of 10 ¿m. A special winding technique in combination with a relatively thin superconducting wire of 230 ¿m diameter provided a significant overall accuracy. In this paper the design and construction aspects of the superconducting Larmor precession magnets will be discussed. Results of the magnetic field optimisation as well as preliminary test results of the magnets are presented. However, the ultimate performance will be investigated when the magnets are put into operation in the new neutron Larmor precession spectrometer at the Institut Laue Langevin

    Sensible and latent heating of the atmosphere as inferred from DST-6 data

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    The average distribution of convective latent heating, boundary layer sensible heat flux, and vertical velocity are determined for the winter 1976 DST period from GLAS model diagnostics. Key features are the regions of intense latent heating over Brazil, Central Africa, and Indonesia; and the regions of strong sensible heating due to air mass modification over the North Atlantic and North Pacific Oceans

    Fractional Lindstedt series

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    The parametric equations of the surfaces on which highly resonant quasi-periodic motions develop (lower-dimensional tori) cannot be analytically continued, in general, in the perturbation parameter, i.e. they are not analytic functions of the perturbation parameter. However rather generally quasi-periodic motions whose frequencies satisfy only one rational relation ("resonances of order 1") admit formal perturbation expansions in terms of a fractional power of the perturbation parameter, depending on the degeneration of the resonance. We find conditions for this to happen, and in such a case we prove that the formal expansion is convergent after suitable resummation.Comment: 40 pages, 6 figure

    The effect of clouds on the earth's radiation balance

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    The effect of global cloudiness on the radiation balance at the top of the atmosphere is studied in general circulation model experiments. Wintertime simulations were conducted with clouds that had realistic optical properties, and were compared with simulations in which the clouds were transparent to either solar or thermal radiation. Clouds increase the net balance by limiting longwave loss to space, but decrease it by reflecting solar radiation. It is found that the net result of cloudiness is to maintain net radiation which is less than would be realized under clear conditions: Clouds cause the net radiation at the top of the atmosphere to increase due to longwave absorption, but to decrease even more due to cloud reflectance of solar radiation

    Towards an optical potential for rare-earths through coupled channels

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    The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations, defined by nuclear deformations. Proper treatment of such excitations is often essential to the accurate description of reaction experimental data. Previous works have applied different models to specific nuclei with the purpose of determining angular-integrated cross sections. In this work, we present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions in a consistent manner for neutron-induced reactions on nuclei in the rare-earth region. This specific subset of the nuclide chart was chosen precisely because of a clear static deformation pattern. We analyze the convergence of the coupled-channel calculations regarding the number of states being explicitly coupled. Inspired by the work done by Dietrich \emph{et al.}, a model for deforming the spherical Koning-Delaroche optical potential as function of quadrupole and hexadecupole deformations is also proposed. We demonstrate that the obtained results of calculations for total, elastic and inelastic cross sections, as well as elastic and inelastic angular distributions correspond to a remarkably good agreement with experimental data for scattering energies above around a few MeV.Comment: 7 pages, 6 figures. Submitted to the proceedings of the XXXVI Reuni\~ao de Trabalho de F\'{\i}sica Nuclear no Brasil (XXXVI Brazilian Workshop on Nuclear Physics), held in Maresias, S\~ao Paulo, Brazil in September 2013, which should be published on AIP Conference Proceeding Series. arXiv admin note: substantial text overlap with arXiv:1311.1115, arXiv:1311.042
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