4,167 research outputs found

    Tetherline system for orbiting satellites

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    A system for tethering one orbiting space vehicle to another was designed so that a tetherline between the vehicles is controlled by a motorized reel which in turn is controlled to deploy, retrieve, or maintain a constant line length while effecting a stabilizing influence on the line. This is accomplished by applying a tension to the line which takes into account the instantaneous length of the line, rate of change of the length of the line, and certain constants which vary depending upon the mode of operation, deployment, retrieval, or station keeping

    Photon-propagation model with random background field: Length scales and Cherenkov limits

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    We present improved experimental bounds on typical length scales of a photon-propagation model with a frozen (time-independent) random background field, which could result from anomalous effects of a static, multiply connected spacetime foam.Comment: 6 pages with revtex4; v3: final versio

    The Relationships Among BMI, Waist Circumference, Weight Loss and Health Indicators

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    Current health recommendations encourage weight loss for overweight and obese individuals. However, the importance of weight to health is still unclear. The purpose of this study was to determine the impact of weight loss on overall health in a sample of adults who have completed a 10 or 12 week weight loss intervention. The study sample included males and females (n =99) between the ages of 27 -64 years that had a BMI of 29-45 kg/m². The study design is a secondary data analysis of data from two different behavioral weight loss interventions. Both interventions prescribed a reduced calorie diet, increased physical activity, and self-monitoring of diet and physical activity. Of the 99 participants, 28 lost greater than 5% of baseline body weight and saw the most significant changes in waist circumference (p\u3c0.001), systolic blood pressure (p=0.004), diastolic blood pressure (p=0.002), and total cholesterol (p=0.001). This group experienced improvements in every lab value tested. More research with larger sample sizes and longer trial periods need to be done in order to strengthen the validity of the weight loss interventions

    Mach 5 inlet CFD and experimental results

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    An experimental research program was conducted in the NASA Lewis Research Center 10 x 10 ft supersonic wind tunnel. The 2-D inlet model was designed to study the Mach 3.0 to 5.0 speed range for an over-under turbojet plus ramjet propulsion system. The model was extensively instrumented to provide both analytical code validation data as well as inlet performance information. Support studies for the program include flow field predictions with both 3-D parabolized Navier-Stokes (PNS) and 3-D full Navier-Stokes (FNS) analytical codes. Analytical predictions and experimental results are compared

    Precise determination of the sigma pole location from a dispersive analysis

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    We review how the use of recent precise data on kaon decays together with forward dispersion relations (FDR) and Roy's equations allow us to determine the sigma resonance pole position very precisely, by using only experimental input. In addition, we present preliminary results for a modified set of Roy-like equations with only one subtraction, that show a remarkable improvement in the precision around the sigma resonance region. For practical applications, these results are shown to be very well approximated by a very simple conformal expansion.Comment: 5 pages, 2 figures. To appear in the proceedings of the Workshop on Scalar Mesons and Related Topics, Lisbon, Portugal, 11-16 Feb 200

    Precise analysis of pion-pion scattering data from Roy equations and forward dispersion relations

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    We review our recent analysis of pion-pion scattering data in terms of Roy equations and Forward Dispersion Relations, and present some preliminary results in terms of a new set of once-subtracted coupled equations for partial waves. The first analysis consists of independent fits to the different pion-pion channels that satisfies rather well the dispersive representation. In the second analysis we constrain the fit with the dispersion relations. The latter provides a very precise and model independent description of data using just analyticity, causality and crossing.Comment: 6 pages, two figures. To appear in the proceedings of the Workshop on Scalar Mesons and Related Topics, Lisbon, Portugal, 11-16 Feb 200
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