1,573 research outputs found

    Ground support data from July 10 to July 29, 1978, for HCMM thermal satellite data of the Powder River Basin, Wyoming

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    Radiometric and meteorological data acquired at three ground stations located approximately 150 km apart in the Powder River Basin, Wyoming, are summarized. The data were collected between July 10 and July 29, 1978, to support the HCMM thermal satellite data acquired during this time period. The parameters measured are direct solar radiance, total solar radiance, sky radiance, air temperature, relative humidity, wind speed, and wind direction. A tabulation of the measurement accuracies is presented

    Geologic applications of thermal-inertia mapping from satellite

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    In the Powder River Basin, Wyo., narrow geologic units having thermal inertias which contrast with their surroundings can be discriminated in optimal images. A few subtle thermal inertia anomalies coincide with areas of helium leakage believed to be associated with deep oil and gas concentrations. The most important results involved delineation of tectonic framework elements some of which were not previously recognized. Thermal and thermal inertia images also permit mapping of geomorphic textural domains. A thermal lineament appears to reveal a basement discontinuity which involves the Homestake Mine in the Black Hill, a zone of Tertiary igneous activity and facies control in oil producing horizons. Applications of these data to the Cabeza Prieta, Ariz., area illustrate their potential for igneous rock type discrimination. Extension to Yellowstone National Park resulted in the detection of additional structural information but surface hydrothermal features could not be distinguished with any confidence. A thermal inertia mapping algorithm, a fast and accurate image registration technique, and an efficient topographic slope and elevation correction method were developed

    Registration of Heat Capacity Mapping Mission day and night images

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    Neither iterative registration, using drainage intersection maps for control, nor cross correlation techniques were satisfactory in registering day and night HCMM imagery. A procedure was developed which registers the image pairs by selecting control points and mapping the night thermal image to the daytime thermal and reflectance images using an affine transformation on a 1300 by 1100 pixel image. The resulting image registration is accurate to better than two pixels (RMS) and does not exhibit the significant misregistration that was noted in the temperature-difference and thermal-inertia products supplied by NASA. The affine transformation was determined using simple matrix arithmetic, a step that can be performed rapidly on a minicomputer

    The high partial wave phenomenon of spin changing atomic transitions

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    The collisional transition between two highly excited atomic states with different spin is investigated theoretically. Taking helium-like n1S − n3P as an example, it is found that the transition is driven in the highly ion-ized Fe ion purely by exchange, and the cross section becomes increasingly dominated by partial waves of high orbital angular momentum as the scattering energy increases. Whereas for the near-neutral Li ion the transition is dominated by channel coupling in low partial waves. Analytical bench-marks and numerical methods are developed for the accurate calculation of the exchange integral at high angular momentum. It is shown how the partial wave and energy dependence of the collision strength for high n spin changing transitions in the highly ionized ion is related to the overlap of the extended atomic orbitals.</p

    Highly Excited Core Resonances in Photoionization of Fe XVII : Implications for Plasma Opacities

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    A comprehensive study of high-accuracy photoionization cross sections is carried out using the relativistic Breit-Pauli R-matrix (BPRM) method for (hnu + Fe XVII --> Fe XVIII + e). Owing to its importance in high-temperature plasmas the calculations cover a large energy range, particularly the myriad photoexciation-of-core (PEC) resonances including the n = 3 levels not heretofore considered. The calculations employ a close coupling wave function expansion of 60 levels of the core ion Fe XVIII ranging over a wide energy range of nearly 900 eV between the n = 2 and n = 3 levels. Strong coupling effects due to dipole transition arrays 2p^5 --> 2p^4 (3s,3d) manifest themselves as large PEC resonances throughout this range, and enhance the effective photoionization cross sections orders of magnitude above the background. Comparisons with the erstwhile Opacity Project (OP) and other previous calculations shows that the currently available cross sections considerably underestimate the bound-free cross sections. A level-identification scheme is used for spectroscopic designation of the 454 bound fine structure levels of Fe XVII. Level-specific photoionization cross sections are computed for all levels. In addition, partial cross sections for leaving the core ion Fe XVII in the ground state are also obtained. These results should be relevant to modeling of astrophysical and laboratory plasma sources requiring (i) photoionization rates, (ii) extensive non-local-thermodynamic-equilibrium models, (iii) total unified electron-ion recombination rates including radiative and dielectronic recombination, and (iv) plasma opacities. We particularly examine PEC and non-PEC resonance strengths and emphasize their expanded role to incorporate inner-shell excitations for improved opacities, as shown by the computed monochromatic opacity of Fe XVII.Comment: 12 pages, 5 figures, Physical Review A (in press

    A brief live interactive normative group intervention using wireless keypads to reduce drinking and alcohol consequences in college student athletes

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    Introduction and Aims Misperceptions of how members of one’s social group think and act influence behaviour. The current study was designed to extend the research of group-specific normative feedback interventions among salient campus groups with heightened risk. Although not a randomised controlled trial, this research used normative feedback that was obtained using wireless keypad technology during a live session, within sex-specific student athlete groups to extend the proof of concept of using this brief interactive intervention. Design and Methods Participants included 660 intercollegiate athletes from all varsity athletic teams at two private, mid-size universities. Intervention data were gathered in vivo using computerised handheld keypads into which group members entered in personal responses to a series of alcohol-related questions. These questions assessed perceptions of normative group behaviour and attitudes as well as actual individual behaviour and attitudes. These data were then immediately presented back in graphical form to illustrate discrepancies between perceived and actual group norms. Results Results revealed that at 1 month post-intervention, perceived group norms, behaviour, attitudes and consequences reduced compared with baseline. These reductions were maintained at 2 month follow up. Latent growth modelling suggested that the reductions in perceived norms and attitudes were associated with reductions in individual drinking behaviour and negative consequences. Discussion and Conclusions These results are among the first to suggest the effectiveness of a novel, group-based normative alcohol intervention among student athletes. Limitations of the design preclude strong inferences about efficacy; however, the findings support further trialling of such information technology in alcohol treatment research

    Model of a fluid at small and large length scales and the hydrophobic effect

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    We present a statistical field theory to describe large length scale effects induced by solutes in a cold and otherwise placid liquid. The theory divides space into a cubic grid of cells. The side length of each cell is of the order of the bulk correlation length of the bulk liquid. Large length scale states of the cells are specified with an Ising variable. Finer length scale effects are described with a Gaussian field, with mean and variance affected by both the large length scale field and by the constraints imposed by solutes. In the absence of solutes and corresponding constraints, integration over the Gaussian field yields an effective lattice gas Hamiltonian for the large length scale field. In the presence of solutes, the integration adds additional terms to this Hamiltonian. We identify these terms analytically. They can provoke large length scale effects, such as the formation of interfaces and depletion layers. We apply our theory to compute the reversible work to form a bubble in liquid water, as a function of the bubble radius. Comparison with molecular simulation results for the same function indicates that the theory is reasonably accurate. Importantly, simulating the large length scale field involves binary arithmetic only. It thus provides a computationally convenient scheme to incorporate explicit solvent dynamics and structure in simulation studies of large molecular assemblies

    X-Ray Photoabsorption in KLL Resonances of O VI And Abundance Analysis

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    It is shown that photoabsorption via autoionizing resonances may be appreciable and used for abundance analysis. Analogous to spectral lines, the `resonance oscillator strength' f_r may be defined and evaluated in terms of the differential oscillator strength df/d(epsilon) that relates bound and continuum absorption. X-ray photoabsorption in KLL (1s2s2p) resonances of O VI is investigated using highly resolved relativistic photoionization cross sections with fine structure. It is found that f_r is comparable to that for UV dipole transition in O VI (2s - 2p) and the X-ray (1s^2 ^1S_0 - 1s2p ^1P^o_1) transition in O VII. The dominant O VI(KLL) components lie at 22.05 and 21.87 Angstroms. These predicted absorption features should be detectable by the Chandra X-Ray Observatory (CXO) and the X-Ray Multi-Mirror Mission (XMM). The combined UV/X-ray spectra of O VI/O VII should yield valuable information on the ionization structure and abundances in sources such as the `warm absorber' region of active galactic nuclei and the hot intergalactic medium. Some general implications of resonant photoabsorption are addressed.Comment: Astrophys. J. Letters (in press), 9 pages, 3 figure

    Comparing Greek-Affiliated Students and Student Athletes: An Examination of the Behavior-Intention Link, Reasons for Drinking, and Alcohol-Related Consequences

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    While affiliation with Greek fraternities/sororities and intercollegiate athletic teams is associated with heavier drinking (Meilman et al., 1999), few studies have compared reasons for drinking among these groups. A sample of 1,541 students, identifying as either Greeks or athletes, completed an online survey. Athletes were significantly higher than Greeks on conformity reason for drinking. Tests of independent correlations indicated the magnitude of the past behavior to intention link was considerably stronger for Greeks. Greeks experienced significantly more social problems from drinking. Several group by gender ANOVA models found significant main effects with highest drinking rates, usually among Greek males, and lowest among female athletes. Understanding these specific group differences informs recommendations for group-specific and tailored educational interventions, which are discussed
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