18,992 research outputs found

    Development of a 25 - 50 watt high efficiency, X-band, traveling wave tube Quarterly report, Nov. 1970 - Jan. 1971

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    Computer design technique of electron gun for use in spacecraft transmitter

    A digital algorithm for spectral deconvolution with noise filtering and peak picking: NOFIPP-DECON

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    Noise-filtering, peak-picking deconvolution software incorporates multiple convoluted convolute integers and multiparameter optimization pattern search. The two theories are described and three aspects of the software package are discussed in detail. Noise-filtering deconvolution was applied to a number of experimental cases ranging from noisy, nondispersive X-ray analyzer data to very noisy photoelectric polarimeter data. Comparisons were made with published infrared data, and a man-machine interactive language has evolved for assisting in very difficult cases. A modified version of the program is being used for routine preprocessing of mass spectral and gas chromatographic data

    Long time deviation from exponential decay: non-integral power laws

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    Quantal systems are predicted to show a change-over from exponential decay to power law decay at very long times. Although most theoretical studies predict integer power-law exponents, recent measurements by Rothe et al. of decay luminescence of organic molecules in solution {Phys. Rev. Lett. 96 (2006) 163601} found non-integer exponents in most cases. We propose a physical mechanism, within the realm of scattering from potentials with long tails, which produces a continuous range of power law exponents. In the tractable case of the repulsive inverse square potential, we demonstrate a simple relation between the strength of the long range tail and the power law exponent. This system is amenable to experimental scrutiny

    The role of virtual reality in built environment education

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    This study builds upon previous research on the integration of Virtual Reality (VR) within the built environment curriculum and aims to investigate the role of VR and three-dimensional (3D) computer modelling on learning and teaching in a school of the built environment. In order to achieve this aim, a number of academic experiences were analysed to explore the applicability and viability of 3D computer modelling and VR into built environment subject areas. Although two-dimensional (2D) representations have been greatly accepted by built environment professions and education, 3D computer representations and VR applications, offering interactivity and immersiveness, are not yet widely accepted. The study attempts to understand the values and challenges of integrating visualisation technologies into built environment teaching and investigates tutors’ perceptions, opinions and concerns with respect to these technologies. The study reports on the integration process and considers how 3D computer modelling and VR technologies can combine with, and extend, the existing range of learning and teaching methods appropriate to different disciplines and programme areas

    Disentanglement and Decoherence without dissipation at non-zero temperatures

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    Decoherence is well understood, in contrast to disentanglement. According to common lore, irreversible coupling to a dissipative environment is the mechanism for loss of entanglement. Here, we show that, on the contrary, disentanglement can in fact occur at large enough temperatures TT even for vanishingly small dissipation (as we have shown previously for decoherence). However, whereas the effect of TT on decoherence increases exponentially with time, the effect of TT on disentanglement is constant for all times, reflecting a fundamental difference between the two phenomena. Also, the possibility of disentanglement at a particular TT increases with decreasing initial entanglement.Comment: 3 page

    Spectra and positions of galactic gamma-ray sources

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    The UCSD/MIT Hard X-Ray and Low Energy Gamma-Ray Experiment aboard HEAO-1 scanned the galactic center region during three epochs in 1977 and 1978 from 13 to 180 keV. The results are presented from the scanning epoch of 1978 September. Twenty-two known 2 to 10 keV source positions were necessary for an acceptable fit to the data. The spectra of the 16 strongest, least confused sources are all consistent with power laws with photon spectral indices ranging from 2.1 to 7.2. Acceptable fits to thermal bremsstrahlung models are also possible for most sources. No one source in this survey can be extrapolated to higher energy to match the intensity of the gamma-ray continuum as measured by HEAO-1 large field of view detectors, which implies that the continuum is a composite of contributions from a number of sources

    Use of Psychological Skills by Risk Sport Athletes

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    Psychological skills can help athletes maximize their physical skills (Smith, Schutz, Smoll, & Ptacek, 1995) and overcome sport-related adversity. These skills may be especially beneficial to athletes performing within natural and unstable risk sport environments. The current study assessed psychological skills among risk sport athletes (N = 232) and the impact of experience on the use of such skills. Risk sport athletes of varying degrees of experience completed a modified version of the Athletic Coping Skills Inventory (ACSI; Smith et al., 1995). Risk sport athletes exceeded the midpoint on all of the ACSI subscales, indicating psychological skills usage. Experienced athletes scored significantly higher (p \u3c .05) on three of the subscales and the total score, then leisure and novice athletes. These findings suggest the use of psychological skills within unpredictable and dynamic risk sport environments
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