13,598 research outputs found

    Food insecurity in veteran households: findings from nationally representative data

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    OBJECTIVE: The present study is the first to use nationally representative data to compare rates of food insecurity among households with veterans of the US Armed Forces and non-veteran households. DESIGN: We used data from the 2005-2013 waves of the Current Population Survey - Food Security Supplement to identify rates of food insecurity and very low food security in veteran and non-veteran households. We estimated the odds and probability of food insecurity in veteran and non-veteran households in uncontrolled and controlled models. We replicated these results after separating veteran households by their most recent period of service. We weighted models to create nationally representative estimates. SETTING: Nationally representative data from the 2005-2013 waves of the Current Population Survey - Food Security Supplement. SUBJECTS: US households (n 388 680). RESULTS: Uncontrolled models found much lower rates of food insecurity (8·4 %) and very low food security (3·3 %) among veteran households than in non-veteran households (14·4 % and 5·4 %, respectively), with particularly low rates among households with older veterans. After adjustment, average rates of food insecurity and very low food security were not significantly different for veteran households. However, the probability of food insecurity was significantly higher among some recent veterans and significantly lower for those who served during the Vietnam War. CONCLUSIONS: Although adjusting eliminated many differences between veteran and non-veteran households, veterans who served from 1975 and onwards may be at higher risk for food insecurity and should be the recipients of targeted outreach to improve nutritional outcomes

    Water vapor in Jupiter's atmosphere

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    High spectral resolution observations of Jupiter at 2.7 and 5 microns acquired from the Kuiper Airborne Observatory were used to infer the vertical distribution of H2O between 0.7 and 6 bars. The H2O mole fraction, qH2O, is saturated for P<2 bars, qH2O = 4x.000001 in the 2 to 4 bar range and it increases to 3x.00001 at 6 bars where T = 288 K. The base of the 5 micron line formation region is determined by pressure-induced H2 opacity. At this deepest accessible level, the O/H ratio in Jupiter is depleted by a factor of 50 with respect to the solar atmosphere. High spatial resolution Voyager IRIS spectra of Jupiter's North Tropical Zone, Equatorial Zone, and Hot Spots in the North and South Equatorial Belt were analyzed to determine the spatial variation of H2O across the planet. The column abundance of H2O above the 4 bar level is the same in the zones as in the SEB Hot Spots, about 20 cm-amgt. A cloud model for Jupiter's belts and zones was developed in order to fit the IRIS 5 micron spectra. An absorbing cloud located at 2 bars whose 5 micron optical thickness varies between 1 in the Hot Spots and 4 in the coldest zones satisfactorily matches the IRIS data

    The Jovian atmospheric window at 2.7 microns: A search for H2S

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    The atmospheric transmission window at 2.7 microns in Jupiter's atmosphere was observed at a spectral resolution of 0.1/cm from the Kuiiper Airborne Observatory. From an analysis of the CH4 abundance (80 m-am) and the H2O abundance ( 0.0125 cm-am) it was determined that the penetration depth of solar flux at 2.7 microns is near the base of the NH3 cloud layer. The upper limit to H2O at 2.7 microns and other results suggest that photolytic reactions in Jupiter's lower troposphere may not be as significant as was previously thought. A search for H2S in Jupiter's atmosphere yielded an upper limit of 0.1 cm-am. The corresponding limit to the element abundance ratio S/H was approx. 1.7x10(-8), about 10(-3) times the solar value. Upon modeling the abundance and distribution of H2S in Jupiter's atmosphere it was concluded that, contrary to expectations, sulfur-bearing chromophores are not present in significant amounts in Jupiter's visible clouds. Rather, it appears that most of Jupiter's sulfur is locked up as NH4SH in a lower cloud layer. Alternatively, the global abundance of sulfur in Jupiter may be significantly depleted

    A method for the estimation of p-mode parameters from averaged solar oscillation power spectra

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    A new fitting methodology is presented which is equally well suited for the estimation of low-, medium-, and high-degree mode parameters from mm-averaged solar oscillation power spectra of widely differing spectral resolution. This method, which we call the "Windowed, MuLTiple-Peak, averaged spectrum", or WMLTP Method, constructs a theoretical profile by convolving the weighted sum of the profiles of the modes appearing in the fitting box with the power spectrum of the window function of the observing run using weights from a leakage matrix that takes into account both observational and physical effects, such as the distortion of modes by solar latitudinal differential rotation. We demonstrate that the WMLTP Method makes substantial improvements in the inferences of the properties of the solar oscillations in comparison with a previous method that employed a single profile to represent each spectral peak. We also present an inversion for the internal solar structure which is based upon 6,366 modes that we have computed using the WMLTP method on the 66-day long 2010 SOHO/MDI Dynamics Run. To improve both the numerical stability and reliability of the inversion we developed a new procedure for the identification and correction of outliers in a frequency data set. We present evidence for a pronounced departure of the sound speed in the outer half of the solar convection zone and in the subsurface shear layer from the radial sound speed profile contained in Model~S of Christensen-Dalsgaard and his collaborators that existed in the rising phase of Solar Cycle~24 during mid-2010

    Star Formation Histories of Nearby Elliptical Galaxies. II. Merger Remnant Sample

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    This work presents high S/NS/N spectroscopic observations of a sample of six suspected merger remnants, selected primarily on the basis of H{\sc i} tidal debris detections. Single stellar population analysis of these galaxies indicates that their ages, metallicities, and α\alpha-enhancement ratios are consistent with those of a representative sample of nearby elliptical galaxies. The expected stellar population of a recent merger remnant, young age combined with low [α\alpha/Fe], is not seen in any H{\sc i}-selected galaxy. However, one galaxy (NGC~2534), is found to deviate from the ZZ-plane in the sense expected for a merger remnant. Another galaxy (NGC~7332), selected by other criteria, best matches the merger remnant expectations.Comment: 12 pages, 10 figures, accepted by A

    Ring Formation in Magnetically Subcritical Clouds and Multiple Star Formation

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    We study numerically the ambipolar diffusion-driven evolution of non-rotating, magnetically subcritical, disk-like molecular clouds, assuming axisymmetry. Previous similar studies have concentrated on the formation of single magnetically supercritical cores at the cloud center, which collapse to form isolated stars. We show that, for a cloud with many Jeans masses and a relatively flat mass distribution near the center, a magnetically supercritical ring is produced instead. The supercritical ring contains a mass well above the Jeans limit. It is expected to break up, through both gravitational and possibly magnetic interchange instabilities, into a number of supercritical dense cores, whose dynamic collapse may give rise to a burst of star formation. Non-axisymmetric calculations are needed to follow in detail the expected ring fragmentation into multiple cores and the subsequent core evolution. Implications of our results on multiple star formation in general and the northwestern cluster of protostars in the Serpens molecular cloud core in particular are discussed.Comment: 25 pages, 4 figures, to appear in Ap

    Unconventional magnets in external magnetic fields

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    This short review surveys phenomena observed when a magnetic field is applied to a system of localised spins on a lattice. Its focus is on frustrated magnets in dimension d≄2d \geq 2. The interplay of field and entropy is illustrated in the context of their unusual magnetocaloric properties, where field-tuned degeneracies assert themselves. Magnetisation plateaux can reveal the physics of fluctuations, with unusual excitations (such as local modes, extended string defects or monopoles) involved in plateau termination. Field-tuning lattice geometry is the final topic, where mechanisms for dimensional reduction and conversion between different lattice types are discussed.Comment: Plenary Talk at HFM 2008 Conferenc

    The Era of Massive Population III Stars: Cosmological Implications and Self-Termination

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    The birth and death of the first generation of stars have important implications for the thermal state and chemical properties of the intergalactic medium (IGM) in the early universe. Sometime after recombination, the neutral, chemically pristine gas was reionized by ultraviolet photons emitted from the first stars, but also enriched with heavy elements when these stars ended their lives as energetic supernovae. Using the results from previous high-resolution cosmological simulations of early structure formation that include radiative transfer, we show that a significant volume fraction of the IGM can be metal-polluted, as well as ionized, by massive Population III stars formed in small-mass (10^6-10^7 Msun) halos early on. If most of the early generation stars die as pair-instability supernovae with energies up to 10^{53} ergs, the volume-averaged mean metallicity will quickly reach Z ~ 10^{-4}Zsun by a redshift of 15-20, possibly causing a prompt transition to the formation of a stellar population that is dominated by low-mass stars. In this scenario, the early chemical enrichment history should closely trace the reionization history of the IGM, and the end of the Population III era is marked by the completion of reionization and pre-enrichment by z=15. We conclude that, while the pre-enrichment may partially account for the ``metallicity-floor'' in high-redshift Lyman-alpha clouds, it does not significantly affect the elemental abundance in the intracluster medium.Comment: Version accepted by ApJ. Minor revisions and a few citations adde

    Entanglement of distant optomechanical systems

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    We theoretically investigate the possibility to generate non-classical states of optical and mechanical modes of optical cavities, distant from each other. A setup comprised of two identical cavities, each with one fixed and one movable mirror and coupled by an optical fiber, is studied in detail. We show that with such a setup there is potential to generate entanglement between the distant cavities, involving both optical and mechanical modes. The scheme is robust with respect to dissipation, and nonlocal correlations are found to exist in the steady state at finite temperatures.Comment: 12 pages (published with minor modifications
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