519 research outputs found

    Letter from M.A. McLaughlin, Boston, Massachusetts, to Anne Whitney, Shelburne, New Hampshire, 1912 June 29

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    https://repository.wellesley.edu/whitney_correspondence/2758/thumbnail.jp

    Dim Isolated Neutron Stars, Cooling and Energy Dissipation

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    The cooling and reheating histories of dim isolated neutron stars(DINs) are discussed. Energy dissipation due to dipole spindown with ordinary and magnetar fields, and due to torques from a fallback disk are considered as alternative sources of reheating which would set the temperature of the neutron star after the initial cooling era. Cooling or thermal ages are related to the numbers and formation rates of the DINs and therefore to their relations with other isolated neutron star populations. Interaction with a fallback disk, higher multipole fields and activity of the neutron star are briefly discussed.Comment: To appear in Astrophysics and Space Science, in the proceedings of the conference "Isolated Neutron Stars: from the Interior to the Surface", London, April 2006; eds. D. Page, R. Turolla and S. Zane. Revised version: with minor change and typos correcte

    Persistent and Transient Blank Field Sources

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    Blank field sources (BFS) are good candidates for hosting dim isolated neutron stars (DINS). The results of a search of BFS in the ROSAT HRI images are revised. We then focus on transient BFS, arguing that they belong to a rather large population. The perspectives of future research on DINS are then discussed.Comment: 3 pages, 0 figures. Paper presented at the Conference "Isolated Neutron Stars: from the interior to the surface", London, April 2006. Astrophysics and Space Science, in pres

    Valence-electron transfer and a metal-insulator transition in a strongly correlated perovskite oxide

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    We present transport and thermal data for the quadruple-perovskites MCu3(Ti1-xRux)4O12 where 0 < x < 1. A metal-insulator transition (MIT) occurs for Ru concentrations x~0.75. At the same time, the Cu2+ antiferromagnetic state is destroyed and it's magnetic entropy suppressed by Ru on a 1:1 basis. This implies that each Ru transfers an electron to a Cu ion and thus the MIT correlates with filling the Cu 3d shell. The Cu spin entropy in this strongly correlated electron material provides a unique probe among MIT systems.Comment: 15 pages, 4 figures, 1 tabl

    Evaluation of the performance of a lateral flow device for quantitative detection of anti-SARS-CoV-2 IgG

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    Introduction: The AbC-19™ lateral flow immunoassay (LFIA) performance was evaluated on plasma samples from a SARS-CoV-2 vaccination cohort, WHO international standards for anti-SARS-CoV-2 IgG (human), individuals ≥2 weeks from infection of RT-PCR confirmed SARS-CoV-2 genetic variants, as well as microorganism serology. Methods: Pre-vaccination to three weeks post-booster samples were collected from a cohort of 111 patients (including clinically extremely vulnerable patients) from Northern Ireland. All patients received Oxford-AstraZeneca COVID-19 vaccination for the first and second dose, and Pfizer-BioNTech for the third (first booster). WHO international standards, 15 samples from 2 variants of concern (Delta and Omicron) and cross-reactivity with plasma samples from other microorganism infections were also assessed on AbC-19™. Results: All 80 (100%) participants sampled post-booster had high positive IgG responses, compared to 38/95 (40%) participants at 6 months post-first vaccination. WHO standard results correlated with information from corresponding biological data sheets, and antibodies to all genetic variants were detected by LFIA. No cross-reactivity was found with exception of one (of five) Dengue virus samples. Conclusion: These findings suggest BNT162b2 booster vaccination enhanced humoral immunity to SARS-CoV-2 from pre-booster levels, and that this antibody response was detectable by the LFIA. In combination with cross-reactivity, standards and genetic variant results would suggest LFIA may be a cost-effective measure to assess SARS-CoV-2 antibody status

    Young star clusters in M31

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    In our study of M31's globular cluster system with MMT/Hectospec, we have obtained high-quality spectra of 85 clusters with ages less than 1 Gyr. With the exception of Hubble V, the young cluster in NGC 205, we find that these young clusters have kinematics and spatial distribution consistent with membership in M31's young disk. Preliminary estimates of the cluster masses and structural parameters, using spectroscopically derived ages and HST imaging, confirms earlier suggestions that M31 has clusters similar to the LMC's young populous clusters.Comment: 4 pages, 1 figure, contributed talk at "Galaxies in the Local Volume" conference in Sydney, July 200

    Chandra Smells a RRAT: X-ray Detection of a Rotating Radio Transient

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    "Rotating RAdio Transients" (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population.Comment: 5 pages, 2 b/w figures, 1 color figure. To appear in the proceedings of "Isolated Neutron Stars", Astrophysics & Space Science, in pres

    Listening to #2A: Applying a Qualitative Method to Twitter Dialogue

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    In this article, we present a project that explored the application of an established qualitative methodology to a novel source of data: microblog postings on the social media platform Twitter, also known as tweets. In particular, we adapted Consensual Qualitative Research (CQR; Hill, Thompson, & Williams, 1997) for use in this analysis. The coinciding aim of the project was to study the cultural impasses that seemed to characterize U.S. society surrounding the 2016 presidential election. Publicly available tweets bearing the hashtag #2A were selected for examination; this hashtag indicated the user’s intention to direct the posting to the attention of Twitter users in the context of the Second Amendment, which refers to citizens’ right to bear arms. The article describes the process by which CQR was modified for this use, profiles the exploratory findings, and present suggestions for subsequent similar research undertakings
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