1,393 research outputs found

    Concurrent Validity of the Face Valid Food Security Measure

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    Our objective was to assess the concurrent validity of the face valid food security categorical algorithm with Hawaii residents. We also hypothesized that there would be differences in food security status between ethnic groups. We used the 18 question indicators of the Core Food Security Module (CFSM) to develop the face valid food security measure. The “face valid” measure was created previously by this research team as a more valid food security measure in Hawaii. Findings compared the face valid categorical measure and the CFSM scale measure with various demographic, economic, dietary variables, and use of assistance programs. The sample included 1,603 Hawaii residents drawn from a statewide telephone survey and a survey of charitable food recipients. Statistical analysis included ANOVA, chi-square, and regression analysis of food security measures with related variables. In general, progressively deteriorating food security status resulted in concurrent decreases in vegetable intake, increased reliance on a cheap, high-fat, high-sodium noodle product, and increased reliance on resource augmentation behaviors. Factors such as a greater number of children, limited savings, and recent loss of a job were found to compromise food security status. WIC benefits, frequent use of a food pantry, and the presence of a senior adult in the household appeared protective. In this sample Asians, except for Filipinos, were more food secure; Hawaiians and Part-Hawaiians, and Samoans, were more likely to experience hunger. Findings were consistent with previous work and suggest that the face valid food security measure does exhibit concurrent validity.

    Loading a vapor cell magneto-optic trap using light-induced atom desorption

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    Low intensity white light was used to increase the loading rate of 87^{87}Rb atoms into a vapor cell magneto-optic trap by inducing non-thermal desorption of Rb atoms from the stainless steel walls of the vapor cell. An increased Rb partial pressure reached a new equilibrium value in less than 10 seconds after switching on the broadband light source. After the source was turned off, the partial pressure returned to its previous value in 1/e1/e times as short as 10 seconds.Comment: 7 pages, 6 figure

    A Readout System for the STAR Time Projection Chamber

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    We describe the readout electronics for the STAR Time Projection Chamber. The system is made up of 136,608 channels of waveform digitizer, each sampling 512 time samples at 6-12 Mega-samples per second. The noise level is about 1000 electrons, and the dynamic range is 800:1, allowing for good energy loss (dE/dxdE/dx) measurement for particles with energy losses up to 40 times minimum ionizing. The system is functioning well, with more than 99% of the channels working within specifications.Comment: 22 pages + 8 separate figures; 2 figures are .jpg photos to appear in Nuclear Instruments and Method

    Loading of a Rb magneto-optic trap from a getter source

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    We study the properties of a Rb magneto-optic trap loaded from a commercial getter source which provides a large flux of atoms for the trap along with the capability of rapid turn-off necessary for obtaining long trap lifetimes. We have studied the trap loading at two different values of background pressure to determine the cross-section for Rb--N2_2 collisions to be 3.5(4)x10^{-14} cm^2 and that for Rb--Rb collisions to be of order 3x10^{-13} cm^2. At a background pressure of 1.3x10^{-9} torr, we load more than 10^8 atoms into the trap with a time constant of 3.3 s. The 1/e lifetime of trapped atoms is 13 s limited only by background collisions.Comment: 5 pages, 5 figure

    Information Systems and Assemblages

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    International audienceThe theme for the 2014 IFIP WG 8.2 working conference was ‘Information Systems and Global Assemblages: (Re)Configuring Actors, Artefacts, Organizations’. The motivation behind the choice of the conference theme has been the increasing appreciation of notions of emergence, heterogeneity and temporality in IS studies. We found that the conference provided an opportune occasion for inviting scholars interested in exploring these notions, their relevance and promise for IS studies. The concept of the ‘assemblage’ [1], already referenced in IS studies, as will be discussed below, and with significant popularity in other fields, such as anthropology, geography and cultural studies, provided the stepping stone for approaching the heterogeneous, emergent and situated nature of information systems and organization. In particular, we opted for highlighting the ‘global assemblage’[2] as a metaphor to talk about challenging yet often creative tensions that emerge as global imperatives (geographical, intellectual, procedural and others) interact with local arrangements of actors, artefacts and organizations. Here ‘global’ does not mean universal or everywhere, but mobile, abstractable, and capable of recontextualization across diverse social and cultural situations.This book provides a collection of contributions by scholars who responded to our invitation, adding depth and breadth to our understanding of the concept and its value for IS studies. At the same time, some contributors chose to discuss emergence, heterogeneity and situatedness in different terms, drawing upon alternative theoretical traditions and concepts. The result has been an engaging and stimulating mix of ideas that points towards the ‘multiple’ trajectories - current and future - of this exciting stream of research

    Scattering of light and atoms in a Fermi-Dirac gas with BCS pairing

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    We theoretically study the optical properties of a Fermi-Dirac gas in the presence of a superfluid state. We calculate the leading quantum-statistical corrections to the standard column density result of the electric susceptibility. We also consider the Bragg diffraction of atoms by means of light-stimulated transitions of photons between two intersecting laser beams. Bardeen-Cooper-Schrieffer pairing between atoms in different internal levels magnifies incoherent scattering processes. The absorption linewidth of a Fermi-Dirac gas is broadened and shifted. Bardeen-Cooper-Schrieffer pairing introduces a collisional local-field shift that may dramatically dominate the Lorentz-Lorenz shift. For the case of the Bragg spectroscopy the static structure function may be significantly increased due to superfluidity in the nearforward scattering.Comment: 13 pages, 6 figures; to appear in PR

    Composite Spin Waves, Quasi-Particles and Low Temperature resistivity in Double Exchange Systems

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    We make a quantum description of the electron low temperature properties of double exchange materials. In these systems there is a strong coupling between the core spin and the carriers spin. This large coupling makes the low energy spin waves to be a combination of ion and electron density spin waves. We study the form and dispersion of these composite spin wave excitations. We also analyze the spin up and down spectral functions of the temperature dependent quasi-particles of this system. Finally we obtain that the thermally activated composite spin waves renormalize the carriers effective mass and this gives rise to a low temperature resistivity scaling as T ^{5/2}.Comment: 4 pages, REVTE

    Dynamics of evaporative cooling in magnetically trapped atomic hydrogen

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    We study the evaporative cooling of magnetically trapped atomic hydrogen on the basis of the kinetic theory of a Bose gas. The dynamics of trapped atoms is described by the coupled differential equations, considering both the evaporation and dipolar spin relaxation processes. The numerical time-evolution calculations quantitatively agree with the recent experiment of Bose-Einstein condensation with atomic hydrogen. It is demonstrated that the balance between evaporative cooling and heating due to dipolar relaxation limits the number of condensates to 9x10^8 and the corresponding condensate fraction to a small value of 4% as observed experimentally.Comment: 5 pages, REVTeX, 3 eps figures, Phys. Rev. A in pres
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