1,037 research outputs found

    A dual-cavity ruby maser for the Ka-band link experiment

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    A 33.68-GHz dual-cavity ruby maser was built to support the Ka-Band Link Experiment (KABLE) conducted with the Mars Observer spacecraft. It has 25 dB of net gain and a 3-dB bandwidth of 85 MHz. Its noise temperature in reference to the cooled feedhorn aperture is 5 K

    Commitments to help by children: Effects on subsequent prosocial self-attributions

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    Children of both sexes and at several ages were or were not induced to make a commitment to help hospitalized children by sorting papers

    Reference guide for data collection: Qualitative social network interviews

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    The purpose of this document is to guide researchers who plan to use qualitative social network methods drawing on our experiences implementing a qualitative study entitled, “The End of Female Genital Mutilation/Cutting in Senegal: Tracing Social Networks, Investigating the Role of Gender and Intergenerational Influence.” Qualitative fieldwork was carried out in two contrasting settings in Senegal: 1) a region with a low prevalence of female genital mutilation/cutting (FGM/C) characterized by ethnic heterogeneity, and 2) a region with a high prevalence of FGM/C characterized by relative ethnic homogeneity. The goal of this research was to investigate the ways in which social interactions and social influence vary along dimensions including gender, class, and generation, and how they influence the dynamics of decisionmaking regarding FGM/C

    On the Wang-Landau Method for Off-Lattice Simulations in the "Uniform" Ensemble

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    We present a rigorous derivation for off-lattice implementations of the so-called "random-walk" algorithm recently introduced by Wang and Landau [PRL 86, 2050 (2001)]. Originally developed for discrete systems, the algorithm samples configurations according to their inverse density of states using Monte-Carlo moves; the estimate for the density of states is refined at each simulation step and is ultimately used to calculate thermodynamic properties. We present an implementation for atomic systems based on a rigorous separation of kinetic and configurational contributions to the density of states. By constructing a "uniform" ensemble for configurational degrees of freedom--in which all potential energies, volumes, and numbers of particles are equally probable--we establish a framework for the correct implementation of simulation acceptance criteria and calculation of thermodynamic averages in the continuum case. To demonstrate the generality of our approach, we perform sample calculations for the Lennard-Jones fluid using two implementation variants and in both cases find good agreement with established literature values for the vapor-liquid coexistence locus.Comment: 21 pages, 4 figure

    A test of non-equilibrium thermodynamics in glassy systems: the soft-sphere case

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    The scaling properties of the soft-sphere potential allow the derivation of an exact expression for the pressure of a frozen liquid, i.e., the pressure corresponding to configurations which are local minima in its multidimensional potential energy landscape. The existence of such a relation offers the unique possibility for testing the recently proposed extension of the liquid free energy to glassy out-of-equilibrium conditions and the associated expression for the temperature of the configurational degrees of freedom. We demonstrate that the non-equilibrium free energy provides an exact description of the soft-sphere pressure in glass states
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