15,641 research outputs found

    A pitfall of piecewise-polytropic equation of state inference

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    The only messenger radiation in the Universe which one can use to statistically probe the Equation of State (EOS) of cold dense matter is that originating from the near-field vicinities of compact stars. Constraining gravitational masses and equatorial radii of rotating compact stars is a major goal for current and future telescope missions, with a primary purpose of constraining the EOS. From a Bayesian perspective it is necessary to carefully discuss prior definition; in this context a complicating issue is that in practice there exist pathologies in the general relativistic mapping between spaces of local (interior source matter) and global (exterior spacetime) parameters. In a companion paper, these issues were raised on a theoretical basis. In this study we reproduce a probability transformation procedure from the literature in order to map a joint posterior distribution of Schwarzschild gravitational masses and radii into a joint posterior distribution of EOS parameters. We demonstrate computationally that EOS parameter inferences are sensitive to the choice to define a prior on a joint space of these masses and radii, instead of on a joint space interior source matter parameters. We focus on the piecewise-polytropic EOS model, which is currently standard in the field of astrophysical dense matter study. We discuss the implications of this issue for the field.Comment: 16 pages, 9 figures. Accepted for publication in MNRA

    Air quality indices from ERTS-1 MSS information

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    Comparison between ground based atmospheric turbidity network measurements and the average scene grayness from MSS Channel 4 data is in progress. Correlation between these two sources is promising. If continued correlation occurs for other ERTS-1 overflight dates and ground test sites, a new operational use of ERTS-1 useful to Federal, state, and international organizations will become available

    High-Resolution K' Imaging of the z = 1.786 Radio Galaxy 3C 294

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    We have obtained imaging in the K' band (~I-band rest frame) of the z=1.786 radio galaxy 3C 294 with the 36-element curvature-sensing adaptive optics system Hokupa`a and the Canada-France-Hawaii Telescope. At a resolution of < \~0."15, the galaxy is seen as a group of small but resolved knots distributed over a roughly triangular region ~1."4 across. The interpretation of the structure depends on the location of the nucleus, as indicated by the compact radio core. Its position is uncertain by > ~0."5 (2-sigma) because of uncertainties in the optical astrometry, but our best estimate places it at or near the southern apex of the distribution. If this location is correct, the most likely interpretation is that of a hidden quasar nucleus illuminating dusty infalling dwarf-galaxy-like clumps having characteristic sizes of ~1.5 kpc.Comment: 8 pages. One figure in gif format. Postscript version including fig. (240 kb) available at http://www.ifa.hawaii.edu/~canaguby/preprints.html To appear in ApJ. Letter

    Investigation of environmental indices from the Earth Resources Technology Satellite

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    The author has identified the following significant results. Land use change, water quality, and air quality indices have been calculated from analysis of ERTS-1 multispectral scanning imagery and computer compatible tapes. Specifications have been developed and discussed for an ERTS-1 environmental monitoring system which help to serve the information needs of environmental managers at the Federal, state, regional, and local level. General conclusions of the investigation are that ERTS-1 data is very useful in land use mapping and updating to 10-15 categories, and can provide an overall measure of air and water turbidity; however, more and better ground truth and possibly additional spacecraft sensors will be required if specific air and water pollutants are to be quantified from satellite data

    Supported internet-delivered cognitive behavioral therapy programs for depression, anxiety, and stress in university students: open, non-randomised trial of acceptability, effectiveness, and satisfaction

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    BACKGROUND: Many university campuses have limited mental health services that cannot cope with the high demand. One alternative is to use internet-delivered cognitive behavioral therapy (iCBT) as a way of tackling barriers such as lack of availability and scheduling issues. OBJECTIVE: This study aimed to assess feasibility, acceptability, effectiveness, and satisfaction of a supported iCBT intervention offering 3 programs on depression, anxiety, and stress to university students. The design was an open or nonrandomized feasibility trial. METHODS: Participants were recruited from 3 counseling centers at a large midwestern University in the United States. Those agreeing to take part chose 1 of 3 iCBT programs-Space from Depression, Space from Anxiety, or Space from Stress -all comprised 8 modules of media-rich interactive content. Participants were supported throughout the trial by a trained professional. The Patient Health Questionnaire 9 (PHQ-9), Generalized Anxiety Disorder 7 (GAD-7) questionnaire, and stress subscale of the Depression Anxiety and Stress Scale (DASS-21) were completed at baseline, 8 weeks, and 3-month follow-up. A Satisfaction With Treatment (SAT) questionnaire was completed at 8 weeks, and qualitative interviews were completed by a subsample of participants at 3 months. RESULTS: A total of 102 participants were recruited, with 52 choosing Space from Anxiety, 31 choosing Space from Depression, and 19 choosing Space from Stress. Mixed-effects models showed a significant decrease in symptoms of depression (Fâ‚„=6.36, P<.001), anxiety (Fâ‚„=7.97, P<.001), and stress (Fâ‚„=8.50, P<.001) over time across all 3 programs. The largest decreases in PHQ-9 scores at 8 weeks were among participants who chose the Space from Depression program (d=0.84); at 3 months, the largest decreases in PHQ-9 scores were among those who chose the Space from Stress program (d=0.74). The largest decreases in GAD-7 scores were among those who chose the Space from Anxiety program (d=0.74 at 8 weeks and d=0.94 at 3 months). The largest decrease in DASS-21 stress subscale scores was among those who chose the Space from Stress program (d=0.49 at 8 weeks and d=1.16 at 3 months). The mean time spent using the platform per session was 27.4 min (SD 33.8), and participants completed 53% (SD 37.6) of the total program content on average. Most (37/53, 69%) participants found the programs helpful or very helpful and liked the convenience and flexibility of the intervention. Qualitative interviews (n=14) indicated the intervention met students' expectations, and they saw it as a valuable complement to face-to-face treatment. CONCLUSIONS: The iCBT programs tested in our study appear to be feasible, acceptable, and effective in a university environment. Participants described the benefits of having a flexible, supported Web-based intervention available on campus. Larger trials should be conducted to further test the effectiveness of supported Web-based interventions that give students a choice of program depending on their symptom profile.Published versio

    Letter to the Editor

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    Measurements of total alkalinity and inorganic dissolved carbon in the Atlantic Ocean and adjacent Southern Ocean between 2008 and 2010

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    Water column dissolved inorganic carbon and total alkalinity were measured during five hydrographic sections in the Atlantic Ocean and Drake Passage. The work was funded through the Strategic Funding Initiative of the UK's Oceans2025 programme, which ran from 2007 to 2012. The aims of this programme were to establish the regional budgets of natural and anthropogenic carbon in the North Atlantic, the South Atlantic, and the Atlantic sector of the Southern Ocean, as well as the rates of change of these budgets. This paper describes in detail the dissolved inorganic carbon and total alkalinity data collected along east–west sections at 47° N to 60° N, 24.5° N, and 24° S in the Atlantic and across two Drake Passage sections. Other hydrographic and biogeochemical parameters were measured during these sections, and relevant standard operating procedures are mentioned here. Over 95% of dissolved inorganic carbon and total alkalinity samples taken during the 24.5° N, 24° S, and the Drake Passage sections were analysed onboard and subjected to a first-level quality control addressing technical and analytical issues. Samples taken along 47° N to 60° N were analysed and subjected to quality control back in the laboratory. Complete post-cruise second-level quality control was performed using cross-over analysis with historical data in the vicinity of measurements, and data were submitted to the CLIVAR and Carbon Hydrographic Data Office (CCHDO), the Carbon Dioxide Information Analysis Center (CDIAC) and and will be included in the Global Ocean Data Analyses Project, version 2 (GLODAP 2), the upcoming update of Key et al. (2004)

    Hole saw drill attachment has zero force reaction

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    Zero reaction tools require no force application by workers in space. The tool accomplishes hole cutting by holding the workpiece and feeding the cutting blade into and through it by forces entirely absorbed within the tool
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