9,447 research outputs found
Parallel line raster eliminates ambiguities in reading timing of pulses less than 500 microseconds apart
Parallel horizontal line raster is used for precision timing of events occurring less than 500 microseconds apart for observation of hypervelocity phenomena. The raster uses a staircase vertical deflection and eliminates ambiguities in reading timing of pulses close to the end of each line
Assessing the sociology of sport: On sports mega-events and capitalist modernity
On the 50th anniversary of the ISSA and IRSS, one of the leading international scholars on sport and consumer culture, John Horne, considers the trajectory and challenges of research on sports mega-events and their place in capitalist modernity. In anchoring work on this topic in Roche’s definition of mega-events, Horne notes that sports mega-events are important symbolic, economic, and political elements in the orientation of nations to stake their place in global society. Fundamental issues about the concept of ‘mega-event’ pose challenges for scholars as questions remain over what qualifies as a sports mega-event and how ‘lived experience’ with such events transacts with media spectacularization and characterization. The essay closes by posing broader questions for further investigation about the economic, political, and social risks and benefits of sports mega-events and how these events may portend and relate to changing relations of economic and political power on a global scale
Remote sensing of water quality in reservoirs and lakes in semi-arid climates
Overlake measurements using aerial cameras (remote sensing) combined with water truth collected from boats most economically provided wide-band photographs rather than precise spectra. With use of false color infrared film (400-950 nm), the reflected spectral signatures seen from hundreds to thousands of meters above the lake merged to produce various color tones. Such colors were easily and inexpensively obtained and could be recognized by lake management personnel without any prior training. The characteristic spectral signatures of various algal types were also recognizable in part by the color tone produced by remote sensing
Highway and runway traction studies - The problem, history, objectives, and NASA program
Review of highway and runway traction studie
Interference and complementarity for two-photon hybrid entangled states
In this work we generate two-photon hybrid entangled states (HES), where the
polarization of one photon is entangled with the transverse spatial degree of
freedom of the second photon. The photon pair is created by parametric
down-conversion in a polarization-entangled state. A birefringent double-slit
couples the polarization and spatial degrees of freedom of these photons and
finally, suitable spatial and polarization projections generate the HES. We
investigate some interesting aspects of the two-photon hybrid interference, and
present this study in the context of the complementarity relation that exists
between the visibilities of the one- and two-photon interference patterns.Comment: 10 pages, 4 figures. Accepted in Physical Review
Relativistic Quasilinear Diffusion in Axisymmetric Magnetic Geometry for Arbitrary-Frequency Electromagnetic Fluctuations
A relativistic bounce-averaged quasilinear diffusion equation is derived to
describe stochastic particle transport associated with arbitrary-frequency
electromagnetic fluctuations in a nonuniform magnetized plasma. Expressions for
the elements of a relativistic quasilinear diffusion tensor are calculated
explicitly for magnetically-trapped particle distributions in axisymmetric
magnetic geometry in terms of gyro-drift-bounce wave-particle resonances. The
resonances can destroy any one of the three invariants of the unperturbed
guiding-center Hamiltonian dynamics.Comment: 22 pages, Latex, to appear in Physics of Plasma
Effects of low energy proton, electron, and simultaneously combined proton and electron environments in silicon and GaAs solar cells
Degradation of silicon and GaAs solar cells due to exposures to low energy proton and electron environments and annealing data for these cells are discussed. Degradation of silicon cells in simultaneously combined electron and low energy proton environments and previous experimental work is summarized and evaluated. The deficiencies in current solar array damage prediction techniques indicated by these data and the relevance of these deficiencies to specific missions such as intermediate altitude orbits and orbital transfer vehicles using solar electric propulsion systems are considered
Heating and cooling of coronal loops with turbulent suppression of parallel heat conduction
Using the "enthalpy-based thermal evolution of loops" (EBTEL) model, we
investigate the hydrodynamics of the plasma in a flaring coronal loop in which
heat conduction is limited by turbulent scattering of the electrons that
transport the thermal heat flux. The EBTEL equations are solved analytically in
each of the two (conduction-dominated and radiation-dominated) cooling phases.
Comparison of the results with typical observed cooling times in solar flares
shows that the turbulent mean free-path lies in a range
corresponding to a regime in which classical (collision-dominated) conduction
plays at most a limited role. We also consider the magnitude and duration of
the heat input that is necessary to account for the enhanced values of
temperature and density at the beginning of the cooling phase and for the
observed cooling times. We find through numerical modeling that in order to
produce a peak temperature ~K and a 200~s cooling time
consistent with observations, the flare heating profile must extend over a
significant period of time; in particular, its lingering role must be taken
into consideration in any description of the cooling phase. Comparison with
observationally-inferred values of post-flare loop temperatures, densities, and
cooling times thus leads to useful constraints on both the magnitude and
duration of the magnetic energy release in the loop, as well as on the value of
the turbulent mean free-path .Comment: 16 pages, 4 figures, to be published in The Astrophysical Journa
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