54,483 research outputs found

    A Search for CO in the Local Group Dwarf Irregular Galaxy WLM

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    We present 12CO J = 1-0 and J = 2-1 observations of the low metallicity (12 + log(O/H) = 7.74) Local Group dwarf irregular galaxy WLM made with the 15 m SEST and 14 m FCRAO telescopes. Despite the presence a number of HII regions, we find no CO emission. We obtain low upper limits on the integrated intensity (I(CO) >= 0.18 K km/s for CO (1-0)). The non-detection is consistent with the result of Taylor, Kobulnicky and Skillman (1998), that dwarf galaxies below a metallicity of ~ 7.9 are not detected in CO emission. WLM shows that this trend continues for low metallicity galaxies even as their metallicities approach 7.9. These results are consistent with the models of the metal poor ISM by Norman and Spaans (1997). By comparing our CO data with observations of star formation in WLM, we find evidence for a high CO to H2_2 conversion factor.Comment: 11 pages, 3 figures, accepted by A&

    NMR Measurements of Power-Law Behavior in the Spin-Wave and Critical Regions of Ferromagnetic EuO

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    Precision continuous-wave NMR measurements have been carried out over the entire magnetization curve of EuO and are presented in tabular form. Two very closely spaced resonances are observed and are attributed to domain and domain-wall signals. Both of the signals are useful for analysis in the spin-wave region. Only the domain signal is measurable above ~50K. The latter is used for fitting Tc and the critical exponent beta. The critical-region fits agree with previous measurements, within experimental error. The low-temperature data exhibit a clear-cut T^2 behavior, at variance with the expectations of conventional spin-wave theory. This result is discussed in relation to two semi-empirical spin-wave schemes, one formulated by N. Bykovetz, and one by U. Koebler. The NMR signal at 4.2K gives no indication of a quadrupole splitting, in contradiction to the interpretation of several previous spin-echo NMR spectra observed in EuO. This issue remains unresolved.Comment: 3 pages, 2 figures, 3 tables. in Proceedings of the 11TH Joint MMM-Intermag Conference, Washington, DC, 201

    Addressing Alcohol\u27s Role in Campus Sexual Assault: A Toolkit by and for Prevention Specialists

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    This toolkit provides specific guidance on addressing alcohol\u27s role in campus sexual assault, centering Sexual Assault Prevention Specialists as the intended audience

    Using Ontology Fingerprints to evaluate genome-wide association study results

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    We describe an approach to characterize genes or phenotypes via ontology fingerprints which are composed of Gene Ontology (GO) terms overrepresented among those PubMed abstracts linked to the genes or phenotypes. We then quantify the biological relevance between genes and phenotypes by comparing their ontology fingerprints to calculate a similarity score. We validated this approach by correctly identifying genes belong to their biological pathways with high accuracy, and applied this approach to evaluate GWA study by ranking genes associated with the lipid concentrations in plasma as well as to prioritize genes within linkage disequilibrium (LD) block. We found that the genes with highest scores were: ABCA1, LPL, and CETP for HDL; LDLR, APOE and APOB for LDL; and LPL, APOA1 and APOB for triglyceride. In addition, we identified some top ranked genes linking to lipid metabolism from the literature even in cases where such knowledge was not reflected in current annotation of these genes. These results demonstrate that ontology fingerprints can be used effectively to prioritize genes from GWA studies for experimental validation

    Distribution, morphology, and genetic affinities of dwarf embedded Fucus populations from the Northwest Atlantic Ocean

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    Dwarf embedded Fucus populations in the Northwest Atlantic Ocean are restricted to the upper intertidal zone in sandy salt marsh environments; they lack holdfasts and are from attached parental populations of F. spiralis or F. spiralis x F. vesiculosus hybrids after breakage and entanglement with halophytic marsh grasses. Dwarf forms are dichotomously branched, flat, and have a mean overall length and width of 20.3 and 1.3 mm, respectively. Thus, they are longer than Irish (mean 9.3 mm) and Alaskan (mean 15.0 mm) populations identified as F cottonii. Reciprocal transplants of different Fucus taxa in a Maine salt marsh confirm that F spiralis can become transformed into dwarf embedded thalli within the high intertidal zone, while the latter can grow into F. s. ecad lutarius within the mid intertidal zone. Thus, vertical transplantation can modify fucoid morphology and result in varying ecads. Microsatellite markers indicate that attached F spiralis and F vesiculosus are genetically distinct, while dwarf forms may arise via hybridization between the two taxa. The ratio of intermediate to species-specific-genotypes decreased with larger thalli. Also, F s. ecad lutarius consists of a mixture of intermediate and pure genotypes, while dwarf thalli show a greater frequency of hybrids

    The magnetoresistance tensor of La(0.8)Sr(0.2)MnO(3)

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    We measure the temperature dependence of the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in c-axis oriented epitaxial thin films of La(0.8)Sr(0.2)MnO(3), for different current directions relative to the crystal axes, and show that both AMR and PHE depend strongly on current orientation. We determine a magnetoresistance tensor, extracted to 4th order, which reflects the crystal symmetry and provides a comprehensive description of the data. We extend the applicability of the extracted tensor by determining the bi-axial magnetocrystalline anisotropy in our samples
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