1,312 research outputs found

    Feasibility of using S-191 infrared spectra for geological studies from space

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    There are no author-identified significant results in this report

    Multispectral signatures in relation to ground control signature using nested sampling approach

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    There are no author-identified significant results in this report

    Communism in North Vietnam

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    The 14.8-h Orbital Period of GX339-4

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    We present the results of photometric observations of the black hole candidate GX339-4, obtained while the system was in an \u27off\u27 state. We show that a 14.8-h modulation was present, and provide evidence for a similar periodicity in the \u27high\u27 state from a reanalysis of previously published photometry and spectroscopy. The presence of the same period in both states implies that it is likely to be the orbital period of the system. The spectroscopy analysis provides evidence for an apparent change in the systemic velocity of the system. The amplitude of the observed radial velocity variations, however, permits only crude limits to be placed on the mass of the compact object. Only absorption-line spectroscopy of the secondary in the \u27off\u27 state will provide a convincing mass determination

    Feasibility of using S-191 infrared spectra for geological studies from space

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    There are no author-identified significant results in this report

    Optical Variability of the Black Hole Candidate GX339-4 (X1659-487, V821 Ara) - Limits on Periodic Modulation

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    We present results of extensive CCD optical photometry (over 1000 frames representing ~150 hr of integration time) of the optical counterpart of the X-ray source GX339–4 obtained during the high (soft) state. The source was seen to be significantly variable. We do not, however, detect any periodic modulation with semi-amplitude greater than ~0.03 mag for periods less than ~0.5 day or semi-amplitude greater than ~0.07 mag for longer periods. An optical spectrum obtained shortly after GX339–4 made a transition from a ‘low’ to a ‘high’ state is also presented and compared with previous results. The width of the He IIλ4686 emission line in the spectrum implies that GX339–4 does not have an unusually low inclination angle and we therefore conclude that the orbital period of GX339–4 is probably longer than ~0.5 day

    Dilemmas in doing insider research in professional education

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    This article explores the dilemmas I encountered when researching social work education in England as an insider researcher who was simultaneously employed as an educator in the host institution. This was an ethnographic project deploying multiple methods and generating rich case study material which informed the student textbook Becoming a Social Worker the four-year period of the project. First, ethical dilemmas emerged around informed consent and confidentiality when conducting surveys of students and reading their portfolios. Second, professional dilemmas stemmed from the ways in which my roles as a researcher, academic tutor, social worker and former practice educator converged and collided. Third, political dilemmas pertained to the potential for the project to crystallize and convey conflicts among stakeholders in the university and community. Since the majority of research in social work education is conducted by insiders, we have a vital interest in making sense of such complexity

    Heme b distributions through the Atlantic Ocean: evidence for "anemic" phytoplankton populations

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    Heme b is an iron-containing cofactor in hemoproteins that participates in the fundamental processes of photosynthesis and respiration in phytoplankton. Heme b concentrations typically decline in waters with low iron concentrations but due to lack of field data, the distribution of heme b in particulate material in the ocean is poorly constrained. Here we report particulate heme b distributions across the Atlantic Ocean (59.9°N to 34.6°S). Heme b concentrations in surface waters ranged from 0.10 to 33.7 pmol L−1 (median = 1.47 pmol L−1, n = 974) and were highest in regions with a high biomass. The ratio of heme b to particulate organic carbon (POC) exhibited a mean value of 0.44 μmol heme b mol−1 POC. We identified the ratio of 0.10 µmol heme b mol−1 POC as the cut-off between heme b replete and heme b deficient (anemic) phytoplankton. By this definition, we observed anemic phytoplankton populations in the Subtropical South Atlantic and Irminger Basin. Comparison of observed and modelled heme b suggested that heme b could account for between 0.17–9.1% of biogenic iron. Our large scale observations of heme b relative to organic matter provide further evidence of the impact of changes in iron supply on phytoplankton iron status across the Atlantic Ocean

    Joint generative model for fMRI/DWI and its application to population

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    Author Manuscript 2011 March 12. 13th International Conference, Beijing, China, September 20-24, 2010, Proceedings, Part IWe propose a novel probabilistic framework to merge information from DWI tractography and resting-state fMRI correlations. In particular, we model the interaction of latent anatomical and functional connectivity templates between brain regions and present an intuitive extension to population studies. We employ a mean-field approximation to fit the new model to the data. The resulting algorithm identifies differences in latent connectivity between the groups. We demonstrate our method on a study of normal controls and schizophrenia patients.National Alliance for Medical Image Computing (U.S.) (NIH NIBIBNAMICU54-EB005149)Neuroimaging Analysis Center (U.S.) (NIH NCRR NAC P41-RR13218)National Institutes of Health (U.S.) (Grant R01MH074794)National Defense Science and Engineering Graduate FellowshipNational Science Foundation (U.S.) (CAREER Grant 0642971
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