13,398 research outputs found

    An exploratory flight investigation of helicopter sling-load placements using a closed-circuit television as a pilot aid

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    Helicopter sling load operations have been limited during pick up and delivery of external cargo by the lack of precision achieved by the combination of pilot, helicopter, and sling load. Use of a closed circuit television as a pilot aid during sling load delivery and placement was documented along with additional cases representing procedures currently employed by military and commercial operators. Although an increase in pilot workload was noted when the television system was used, the results indicated a comparable level of performance for each test case

    Self-steepening of light pulses

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    Self-steepening of light pulses due to propagation in medium with intensity-dependent index of refractio

    Communications systems technology assessment study. Volume 2: Results

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    The cost and technology characteristics are examined for providing special satellite services at UHF, 2.5 GHz, and 14/12 GHz. Considered are primarily health, educational, informational and emergency disaster type services. The total cost of each configuration including space segment, earth station, installation operation and maintenance was optimized to reduce the user's total annual cost and establish preferred equipment performance parameters. Technology expected to be available between now and 1985 is identified and comparisons made between selected alternatives. A key element of the study is a survey of earth station equipment updating past work in the field, providing new insight into technology, and evaluating production and test methods that can reduce costs in large production runs. Various satellite configurations were examined. The cost impact of rain attenuation at Ku-band was evaluated. The factors affecting the ultimate capacity achievable with the available orbital arc and available bandwidth were analyzed

    Introduction to Animal Therapy and its Related Tax Benefits

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    How are animals being used to improve the emotional and physical health of individuals? What are the tax implications associated with service and therapy animals? We examine these questions by providing an introduction to the subject of Animal Assisted Therapy, including how therapists and counselors are routinely using therapy animals in both individual and group treatment settings. Additionally, we discuss the potential tax savings that may be available to counselors and their clients who are using service and therapy animals. We also offer recommendations and guidance for counselors who wish to incorporate animal therapy into their treatment options

    New Constraints on Neutralino Dark Matter in the Supersymmetric Standard Model

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    We investigate the prospects for neutralino dark matter within the Supersymmetric Standard Model (SSM) including the constraints from universal soft supersymmetry breaking and radiative breaking of the electroweak symmetry. The latter is enforced by using the one-loop Higgs effective potential which automatically gives the one-loop corrected Higgs boson masses. We perform an exhaustive search of the allowed five-dimensional parameter space and find that the neutralino relic abundance Ωχh02\Omega_\chi h^2_0 depends most strongly on the ratio ξ0≡m0/m1/2\xi_0\equiv m_0/m_{1/2}. For ξ0≫1\xi_0\gg1 the relic abundance is almost always much too large, whereas for ξ0≪1\xi_0\ll1 the opposite occurs. For ξ0∼1\xi_0\sim1 there are wide ranges of the remaining parameters for which Ωχ∼1\Omega_\chi\sim1. We also determine that m_{\tilde q}\gsim250\GeV and m_{\tilde l}\gsim100\GeV are necessary in order to possibly achieve Ωχ∼1\Omega_\chi\sim1. These lower bounds are much weaker than the corresponding ones derived previously when radiative breaking was {\it not} enforced.Comment: 12 pages plus 6 figures (not included), CERN-TH.6584/92, CTP-TAMU-56/92, UAHEP921

    Detection of quantum light in the presence of noise

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    Detection of quantum light in the presence of dark counts and background radiation noise is considered. The corresponding positive operator-valued measure is obtained and photocounts statistics of quantum light in the presence of noise is studied.Comment: 4 pages, 1 figure; misprints correcte

    Cell-Surface Receptor Expression on Monocytes of Young and Old Mice

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    Background. Monocyte assessment is used in aging research. In humans, reduced expression of toll-like receptors, T-lymphocyte priming receptors and increases in intracellular adhesion molecules on monocytes have been associated with functional decrements, resulting in increased disease risk. While use of mouse models is extensive in aging research, mouse monocyte assessment is rare. We aimed to evaluate differences in cell-surface protein expression in classic (CD115+/Gr-1high) and non-classic (CD115+/Gr-1low) monocyte subsets of old and young mice. Methods. Venous blood was drawn from 18 old (80-wks) and 18 young CD-1 mice (15-20-wks). Flow cytometry was used to assess subpopulations of CD115+ monocytes for TLR2, TLR4, CD80, CD86, MHC II, CD54 and CD25. Data were analyzed with 2 (age groups) x 2 (monocyte populations) repeated measures ANOVA; significance was set at P\u3c0.05. Results. Old mice had greater proportions of classic monocytes (P\u3c0.05). TLR4 and CD80 was 27% and 37% lower in classic monocytes of old mice (P\u3c0.05). Body weight was not a significant covariate in the analysis. Conclusions. We found that old mice had elevated classic monocyte proportions and with lower expression of TLR4 and CD80. Because similar findings in older adults have been associated with increased risk of cardiovascular disease and infection, we surmise that old mice were also had increased disease risk compared to young mice. These findings support the use of monocyte subset phenotyping in murine models of aging

    Milli-second Oscillations in the Persistent and Bursting Flux of Aql X-1 During an Outburst

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    The Rossi X-Ray Timing Explorer observed the soft X-Ray transient Aql X-1 during its outburst in February and March 1997. We report the discovery of quasi-periodic oscillations (QPOs) in its persistent flux with frequencies in the range of 740 to 830 Hz, Q-value of over 100, and a fractional RMS amplitude of (6.8 +- 0.6)%, and nearly coherent oscillations (NCOs) during a Type-I burst with a frequency of 549 Hz. The frequency of the QPOs in the persistent flux is correlated with the mass accretion rate on time scale of hours, but not on time scale of days. This is most likely the manifestation in a single source of the kHz QPO puzzle observed among many sources, i.e., on the one hand, individual sources show a correlation between the QPO frequency and the inferred mass accretion rate, on the other hand, the dozen or so sources with luminosities spanning two decades have essentially the same QPO frequencies. We propose that this multi-valued QPO frequency and mass accretion rate correlation indicates the existence of many similar regimes of the accretion disk. These regimes, with a very similar energy spectrum and QPO frequency, are distinguished from each other by the mass accretion rate or the total X-ray flux. The NCOs during the burst can be made almost perfectly coherent by taking into account a large frequency derivative. This strongly suggests that this frequency is related to the neutron star spin frequency. The large frequency derivative is attributable to the expansion or contraction of the neutron star photosphere during the burst.Comment: 6 pages, LaTex (aas2pp4), Accepted for publication in ApJ Let
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