981 research outputs found

    A Warp in Progress : H I and Radio Continuum Observations of the Spiral NGC 3145

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    Date of Acceptance: 16/06/2015We present VLA H I and 6 cm radio continuum observations of the spiral NGC 3145 and H I observations of its two companions, NGC 3143 and PGC 029578. In optical images NGC 3145 has stellar arms that appear to cross, forming "X"-features. Our radio continuum observations rule out shock fronts at 3 of the 4 "X"-features. In the middle-to-outer disk, the H I line-profiles of NGC 3145 are skewed. Relative to the disk, the gas in the skewed wing of the line-profiles has z-motions away from us on the approaching side of the galaxy and z-motions of about the same magnitude (about 40 km/s) towards us on the receding side. These warping motions imply that there has been a perturbation with a sizeable component perpendicular to the disk over large spatial scales. Two features in NGC 3145 have velocities indicating that they are out-of-plane tidal arms. One is an apparent branch of a main spiral arm; the velocity of the branch is 150 km/s greater than the spiral arm where they appear to intersect in projection. The other is an arm that forms 3 of the "X"-features. It differs in velocity by 56 km/s from the disk at the same projected location. Based on its SFR and H I properties, NGC 3143 is the more likely of the two companions to have interacted with NGC 3145 recently. A simple analytic model demonstrates that an encounter between NGC 3143 and NGC 3145 is a plausible explanation for the observed warping motions in NGC 3145.Peer reviewe

    High star formation rates in turbulent atomic-dominated gas in the interacting galaxies IC 2163 and NGC 2207

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    This is a pre-copyedited, author produced PDF of an article accepted for publication in The Astrophysical Journal following peer review. The version of record (The Astrophysical Journal, 823:26, 2016 May 18) is available on line at doi:10.3847/0004-637X/823/1/26 © 2016. The American Astronomical Society. All rights reserved.CO observations of the interacting galaxies IC 2163 and NGC 2207 are combined with HI, Halpha and 24 microns to study the star formation rate (SFR) surface density as a function of the gas surface density. More than half of the high SFR regions are HI dominated. When compared to other galaxies, these HI-dominated regions have excess SFRs relative to their molecular gas surface densities but normal SFRs relative to their total gas surface densities. The HI-dominated regions are mostly located in the outer part of NGC 2207, where the HI velocity dispersion is high, 40 - 50 km/s. We suggest that the star-forming clouds in these regions have envelopes at lower densities than normal, making them predominantly atomic, and cores at higher densities than normal because of the high turbulent Mach numbers. This is consistent with theoretical predictions of a flattening in the density probability distribution function for compressive, high Mach number turbulence.Peer reviewedFinal Accepted Versio

    Interstellar Turbulence II: Implications and Effects

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    Interstellar turbulence has implications for the dispersal and mixing of the elements, cloud chemistry, cosmic ray scattering, and radio wave propagation through the ionized medium. This review discusses the observations and theory of these effects. Metallicity fluctuations are summarized, and the theory of turbulent transport of passive tracers is reviewed. Modeling methods, turbulent concentration of dust grains, and the turbulent washout of radial abundance gradients are discussed. Interstellar chemistry is affected by turbulent transport of various species between environments with different physical properties and by turbulent heating in shocks, vortical dissipation regions, and local regions of enhanced ambipolar diffusion. Cosmic rays are scattered and accelerated in turbulent magnetic waves and shocks, and they generate turbulence on the scale of their gyroradii. Radio wave scintillation is an important diagnostic for small scale turbulence in the ionized medium, giving information about the power spectrum and amplitude of fluctuations. The theory of diffraction and refraction is reviewed, as are the main observations and scintillation regions.Comment: 46 pages, 2 figures, submitted to Annual Reviews of Astronomy and Astrophysic

    Minimum Wage Channels of Adjustment

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    Industrial Relations, forthcoming Abstract: The effects of minimum wage increases in 2007-2009 are analyzed using a sample of restaurants from Georgia/Alabama. Store-level payroll records provide precise measures of compliance costs. Examined are multiple adjustment channels. Exploiting variation in compliance costs across restaurants, we find employment and hours responses to be variable and in most cases statistically insignificant. Channels of adjustment to wage increases and to changes in non-labor costs include prices, profits, wage compression, turnover, and performance standards

    Primordialists and Constructionists: a typology of theories of religion

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    This article adopts categories from nationalism theory to classify theories of religion. Primordialist explanations are grounded in evolutionary psychology and emphasize the innate human demand for religion. Primordialists predict that religion does not decline in the modern era but will endure in perpetuity. Constructionist theories argue that religious demand is a human construct. Modernity initially energizes religion, but subsequently undermines it. Unpacking these ideal types is necessary in order to describe actual theorists of religion. Three distinctions within primordialism and constructionism are relevant. Namely those distinguishing: a) materialist from symbolist forms of constructionism; b) theories of origins from those pertaining to the reproduction of religion; and c) within reproduction, between theories of religious persistence and secularization. This typology helps to make sense of theories of religion by classifying them on the basis of their causal mechanisms, chronology and effects. In so doing, it opens up new sightlines for theory and research

    Genetically determined Amerindian ancestry correlates with increased frequency of risk alleles for systemic lupus erythematosus

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    Objective To assess whether genetically determined Amerindian ancestry predicts increased presence of risk alleles of known susceptibility genes for systemic lupus erythematosus (SLE). Methods Single-nucleotide polymorphisms (SNPs) within 16 confirmed genetic susceptibility loci for SLE were genotyped in a set of 804 Mestizo lupus patients and 667 Mestizo healthy controls. In addition, 347 admixture informative markers were genotyped. Individual ancestry proportions were determined using STRUCTURE. Association analysis was performed using PLINK, and correlation between ancestry and the presence of risk alleles was analyzed using linear regression. Results A meta-analysis of the genetic association of the 16 SNPs across populations showed that TNFSF4 , STAT4 , ITGAM , and IRF5 were associated with lupus in a Hispanic Mestizo cohort enriched for European and Amerindian ancestry. In addition, 2 SNPs within the major histocompatibility complex region, previously shown to be associated in a genome-wide association study in Europeans, were also associated in Mestizos. Using linear regression, we predicted an average increase of 2.34 risk alleles when comparing an SLE patient with 100% Amerindian ancestry versus an SLE patient with 0% Amerindian ancestry ( P < 0.0001). SLE patients with 43% more Amerindian ancestry were predicted to carry 1 additional risk allele. Conclusion Our results demonstrate that Amerindian ancestry is associated with an increased number of risk alleles for SLE.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78480/1/27753_ftp.pd

    Switching Multiple Sclerosis Patients with Breakthrough Disease to Second-Line Therapy

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    BACKGROUND: Multiple sclerosis (MS) patients with breakthrough disease on immunomodulatory drugs are frequently offered to switch to natalizumab or immunosuppressants. The effect of natalizumab monotherapy in patients with breakthrough disease is unknown. METHODS: This is an open-label retrospective cohort study of 993 patients seen at least four times at the University of California San Francisco MS Center, 95 had breakthrough disease on first-line therapy (60 patients switched to natalizumab, 22 to immunosuppressants and 13 declined the switch [non-switchers]). We used Poisson regression adjusted for potential confounders to compare the relapse rate within and across groups before and after the switch. RESULTS: In the within-group analyses, the relapse rate decreased by 70% (95% CI 50,82%; p<0.001) in switchers to natalizumab and by 77% (95% CI 59,87%; p<0.001) in switchers to immunosuppressants; relapse rate in non-switchers did not decrease (6%, p =  0.87). Relative to the reduction among non-switchers, the relapse rate was reduced by 68% among natalizumab switchers (95% CI 19,87%; p = 0.017) and by 76% among the immunosuppressant switchers (95% CI 36,91%; p = 0.004). CONCLUSIONS: Switching to natalizumab or immunosuppressants in patients with breakthrough disease is effective in reducing clinical activity of relapsing MS. The magnitude of the effect and the risk-benefit ratio should be evaluated in randomized clinical trials and prospective cohort studies

    Herschel Spectroscopic Observations of Little Things Dwarf Galaxies

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    We present far-infrared (FIR) spectral line observations of five galaxies from the Little Things sample: DDO 69, DDO 70, DDO 75, DDO 155, and WLM. While most studies of dwarfs focus on bright systems or starbursts due to observational constraints, our data extend the observed parameter space into the regime of low surface brightness dwarf galaxies with low metallicities and moderate star formation rates. Our targets were observed with Herschel at the [C ii] 158 m,[Oi]63m, [O i] 63 m, [O iii] 88 m,and[Nii]122m, and [N ii] 122 m emission lines using the PACS Spectrometer. These high-resolution maps allow us for the first time to study the FIR properties of these systems on the scales of larger star-forming complexes. The spatial resolution in our maps, in combination with star formation tracers, allows us to identify separate photodissociation regions (PDRs) in some of the regions we observed. Our systems have widespread [C ii] emission that is bright relative to continuum, averaging near 0.5% of the total infrared (TIR) budgetmdashhigher than in solar-metallicity galaxies of other types. [N ii] is weak, suggesting that the [C ii] emission in our galaxies comes mostly from PDRs instead of the diffuse ionized interstellar medium (ISM). These systems exhibit efficient cooling at low dust temperatures, as shown by ([O i]+[C ii])/TIR in relation to 60 m/100m/100 m, and low [O i]/[C ii] ratios which indicate that [C ii] is the dominant coolant of the ISM. We observe [O iii]/[C ii] ratios in our galaxies that are lower than those published for other dwarfs, but similar to levels noted in spirals.Peer reviewedFinal Accepted Versio
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