2,108 research outputs found

    An Old Nurse from Egypt

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    Includes bibliographical reference

    Ray stability in weakly range-dependent sound channels

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    Ray stability is investigated in environments consisting of a range-independent background sound-speed profile on which a range-dependent perturbation, such as that produced by internal waves in deep ocean environments, is superimposed. Numerical results show that ray stability is strongly influenced by the background sound speed profile. Ray instability is shown to increase with increasing magnitude of alpha := I omega^{prime} / omega, where 2 pi / omega(I) is the range of a ray double loop and I is the ray action variable. The mechanism, shear-induced instability enhancement, by which alpha controls ray instability is described.Comment: To appear in JAS

    The impact of satellite temperature soundings on the forecasts of a small national meteorological service

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    The impact of introducing satellite temperature sounding data on a numerical weather prediction model of a national weather service is evaluated. A dry five level, primitive equation model which covers most of the Northern Hemisphere, is used for these experiments. Series of parallel forecast runs out to 48 hours are made with three different sets of initial conditions: (1) NOSAT runs, only conventional surface and upper air observations are used; (2) SAT runs, satellite soundings are added to the conventional data over oceanic regions and North Africa; and (3) ALLSAT runs, the conventional upper air observations are replaced by satellite soundings over the entire model domain. The impact on the forecasts is evaluated by three verification methods: the RMS errors in sea level pressure forecasts, systematic errors in sea level pressure forecasts, and errors in subjective forecasts of significant weather elements for a selected portion of the model domain. For the relatively short range of the present forecasts, the major beneficial impacts on the sea level pressure forecasts are found precisely in those areas where the satellite sounding are inserted and where conventional upper air observations are sparse. The RMS and systematic errors are reduced in these regions. The subjective forecasts of significant weather elements are improved with the use of the satellite data. It is found that the ALLSAT forecasts are of a quality comparable to the SAR forecasts

    Slicing of Silicon into Sheet Material. Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Solar Array Project

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    The use of multiblade slurry sawing to produce silicon wafers from ingots was investigated. The commercially available state of the art process was improved by 20% in terms of area of silicon wafers produced from an ingot. The process was improved 34% on an experimental basis. Economic analyses presented show that further improvements are necessary to approach the desired wafer costs, mostly reduction in expendable materials costs. Tests which indicate that such reduction is possible are included, although demonstration of such reduction was not completed. A new, large capacity saw was designed and tested. Performance comparable with current equipment (in terms of number of wafers/cm) was demonstrated

    Adolescents’ and Young Adults’ Knowledge and Beliefs About Constituents in Novel Tobacco Products

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    Novel tobacco products, such as little cigars, cigarillos, hookah, and e-cigarettes, and their smoke or aerosol contain chemicals which the FDA has determined to be Harmful or Potentially Harmful Constituents. We explored adolescents’ and young adults’ knowledge and beliefs about constituents in novel tobacco products and their smoke or aerosol, in order to inform risk communication messages

    A 16-yr Comparison of Fine Particle and Aerosol Strong Acidity at the Interface Zone (1,540 m) and Within (452 m) the Planetary Boundary Layer of the Great Gulf and Presidential-Dry River Class I Wildernesses on the Presidential Range, New Hampshire

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    Mount Washington, NH in the White Mountain National Forest, is flanked to the north-northeast and south by two Class I Wilderness areas, the Great Gulf and Presidential Range-Dry River Wildernesses, respectively. The Clean Air Act protects Class I area natural resource values from air pollution. Aerosol sulfate, a fine particulate component that is often transported long distances, is a known contributor to visibility degradation and acidic deposition. We examined summertime fine particulate aerosol mass and sulfate, strong acidity and ammonium concentrations from 1988 to 2004 on Mount Washington at two elevations, 452 and 1,540 meters (msl). The former site is within, and the latter at the interface of, the planetary boundary layer. Comparisons of sampling interval durations (10 and 24 hours), site vs. site, and different sampling methods are made. We also examine the extent to which aerosol sulfate is neutralized. Ten hour (daytime) compared to 24 hour samples have higher mass and aerosol sulfate concentrations, however paired samples are well correlated. Fine mass concentrations compared between the 452 m and 1,540 m sites (standard temperature and pressure corrected) show a weak positive linear relationship with the later being approximately 34% lower. We attribute the lack of a strong correlation to the facts that the 1,540 m site is commonly at the interface of and even above the regional planetary boundary layer in summer and that it can intercept different air masses relative to the 452 m site. Sulfate is approximately 19% lower at the higher elevation site, but comprises a greater percentage of total fine mass; 42% compared to 35% for the high and low elevation site, respectively. Aerosol strong acidity was found to increase with increasing sulfate concentrations at both sites. At the high elevation site, elevated mass and sulfate concentrations are associated with westerly and southwesterly regional flows

    Reliability of self-report of health in juvenile offenders

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    The aim of the present study was to investigate the accuracy of self-reports of juvenile offenders on physical factors (e.g., sleep difficulties, weight related behaviors and weight perceptions), health risk behaviors (e.g., alcohol use), trauma history (e.g., physical and sexual abuse) and psychological factors (e.g., anxiety, suicidal and self-harm behaviors). Self-reports obtained via a Health Questionnaire from 242 incarcerated juvenile offenders were compared with standardized measures (Body Mass Index, Adolescent Psychopathology Scale and Child Trauma Questionnaire) to investigate the reliability (via construct validity) and veracity of their self-report. Using kappa estimates and receiver operating characteristic curves, results generally showed high agreement across measures, suggesting that self-report questions from the health survey could all be used reliably. The degree of accuracy indicated that young offenders are as reliable as clinical and community samples of adolescents in their self-report. These findings have implications for routine assessments and practice evaluations that rely on self-report as the method of data collection and as the basis for clinical formulation and treatment planning
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