5,693 research outputs found

    Evaluation of meteorological airborne Doppler radar

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    This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research

    Is Explicit Congestion Notification usable with UDP?

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    We present initial measurements to determine if ECN is usable with UDP traffic in the public Internet. This is interesting because ECN is part of current IETF proposals for congestion control of UDPbased interactive multimedia, and due to the increasing use of UDP as a substrate on which new transport protocols can be deployed. Using measurements from the author’s homes, their workplace, and cloud servers in each of the nine EC2 regions worldwide, we test reachability of 2500 servers from the public NTP server pool, using ECT(0) and not-ECT marked UDP packets. We show that an average of 98.97% of the NTP servers that are reachable using not-ECT marked packets are also reachable using ECT(0) marked UDP packets, and that ~98% of network hops pass ECT(0) marked packets without clearing the ECT bits. We compare reachability of the same hosts using ECN with TCP, finding that 82.0% of those reachable with TCP can successfully negotiate and use ECN. Our findings suggest that ECN is broadly usable with UDP traffic, and that support for use of ECN with TCP has increased

    ANGULAR MOMENTUM IN JUMPS WITH ROTATIONS ON THE LONGITUDINAL AXIS IN FIGURE SKATING -3D-ANALYSES AND COMPUTER SIMULATION

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    INTRODUCTION -In analyses of athletic technique in figure skating primarily jumps with tripie or four-time rotations on the longitudinal axis are considered The quality of these jumps is essentially influenced by vertical momentum and angular momentum. While vertical momentum can be obtained without problems from flight parameters the calculation of angular momentum does represent a much more complicated problem. The task is to optimise vertical and angular momentum and to answer the question for reasons causing that the longitudinal axis is tilted during flight. This is important since a slightly tilled position of this axis can cause a fall in figure skating. Analyses of errors therefore mostly concentrate on the identification of reasons for this tilted position during flight already in the take-off. Therefore 3D monitoring only is insufficient for recommendations on sports techniques but additional 3D calculations (e.g. calculation and three-dimensional presentation of angular momentum) have to be performed. METHODS -A procedure for a threedimensional presentation of angular momentum as vector is presented. Using this procedure reasons for errors can be determined and general orientations for sport technical models can be characterised. Another procedure offers the opportunity to quantify the partial contribution of individual parts of the body in producing angular momentum. To determine the efficient use of the produced angular momentum 3D computer simulation is applied RESULTS 1. The influence of the angle between longitudinal axis and direction of angular momentum on the efficient use of the produced angular momentum is determined as a result of computer simulation 2 The influence of movements of individual parts of the body on the production of the total angular momentum as a reason for tilting the longitudinal axis during flight is studied. 3. We study practical applications in sports practice to present conclusions for the training of sports technique We give recommendations for individual solutions concerning sports technique res. general models to optimise sports technique of the most complicated technical elements. Using the example of the triple Axel, the most complicated triple jump in figure skating, we present opportunities for an interpretation of our results in sports practice

    Promoting adherence to antiretroviral therapy: the experience from a primary care setting in Khayelitsha, South Africa.

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    OBJECTIVE: To describe the approach used to promote adherence to antiretroviral therapy (ART) and to present the outcomes in the first primary care public sector ART project in South Africa. DESIGN: The study is a prospective open cohort, including all adult patients naive to previous ART who received antiretroviral treatment in Khayelitsha, from May 2001 to the end of 2002. Patients were followed until their most recent visit before 31 July 2003. METHODS: Plasma viral load was determined at 3, 6, 12, 18 and 24 months after ART was initiated, and CD4 cell counts 6-monthly. Kaplan-Meier estimates were determined for the cumulative proportions of patients surviving, and patients with viral load suppression and viral rebound. RESULTS: A total of 287 patients were initiated on triple therapy. The probability of survival was 86.3% at 24 months. The median CD4 cell count gain was 288 cells/microliters at 24 months. Viral load was less than 400 copies/ml in 89.2, 84.2 and 69.7% of patients at 6, 12 and 24 months, respectively. The cumulative probability of viral rebound (two consecutive HIV-RNA measurements above 400 copies/ml) after achieving an HIV-RNA measurement below 400 copies/ml was 13.2% at 18 months. CONCLUSION: The study shows that, with a standard approach to patient preparation and strategies to enhance adherence, a cohort of patients on ART can be retained in a resource-limited setting in a developing country. A high proportion of patients achieved suppression of viral replication. The subsequent probability of viral rebound was low

    A Comparative Analysis of the Nativity Wealth Gap

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    This paper investigates the source of the gap in the relative wealth position of immigrant households residing in Australia, Germany and the United States. Our results indicate that in Germany and the United States wealth differentials are largely the result of disparity in the educational attainment and demographic composition of the native and immigrant populations, while income differentials are relatively unimportant in understanding the nativity wealth gap. In contrast, the relatively small wealth gap between Australian- and foreign-born households exists because immigrants to Australia do not translate their relative educational and demographic advantage into a wealth advantage. On balance, our results point to substantial cross-national disparity in the economic well-being of immigrant and native families, which is largely consistent with domestic labor markets and the selection policies used to shape the nature of the immigration flow.international migration, wealth accumulation

    A Comparative Analysis of the Nativity Wealth Gap

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    This paper investigates the source of the gap in the relative wealth position of immigrant households residing in Australia, Germany and the United States. Our results indicate that in Germany and the United States wealth differentials are largely the result of disparity in the educational attainment and demographic composition of the native and immigrant populations, while income differentials are relatively unimportant in understanding the nativity wealth gap. In contrast, the relatively small wealth gap between Australian- and foreign- born households exists because immigrants to Australia do not translate their relative educational and demographic advantage into a wealth advantage. On balance, our results point to substantial cross-national disparity in the economic well-being of immigrant and native families, which is largely consistent with domestic labor markets and the selection policies used to shape the nature of the immigration flow.International migration, wealth accumulation

    A Comparative Analysis of the Nativity Wealth Gap

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    This paper investigates the source of the gap in the relative wealth position of immigrant households residing in Australia, Germany and the United States. Our results indicate that in German and the United States wealth differentials are largely the result of disparity in the educational attainment and demographic composition of the native and immigrant populations, while income differentials are relatively unimportant in understanding the nativity wealth gap. In contrast, the relatively small wealth gap between Australian and foreign-born households, exists because immigrants to Australia do not translate their relative educational and demographic advantage into a wealth advantage. On balance, our results point to substantial cross-nationality disparity in the economic well-being of immigrant and native families, which is largely consistent with domestic labor markets and the selection policies used to shape the nature of immigration flow.International migration, wealth accumulation

    Observation of infinite-range intensity correlations above, at and below the 3D Anderson localization transition

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    We investigate long-range intensity correlations on both sides of the Anderson transition of classical waves in a three-dimensional (3D) disordered material. Our ultrasonic experiments are designed to unambiguously detect a recently predicted infinite-range C0 contribution, due to local density of states fluctuations near the source. We find that these C0 correlations, in addition to C2 and C3 contributions, are significantly enhanced near mobility edges. Separate measurements of the inverse participation ratio reveal a link between C0 and the anomalous dimension \Delta_2, implying that C0 may also be used to explore the critical regime of the Anderson transition.Comment: 13 pages, 11 figures (main text plus supplemental information). Updated version includes an improved introductory paragraph, minor text revisions, a revised title and additional supplemental information on the experimental detail

    Spatial Symmetry Breaking in the Belousov-Zhabotinsky Reaction with Light-Induced Remote Communication

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    Domains containing spiral waves form on a stationary background in a photosensitive Belousov-Zhabotinsky reaction with light-induced alternating nonlocal feedback. Complex behavior of colliding and splitting wave fragments is found with feedback radii comparable to the spiral wavelength. A linear stability analysis of the uniform stationary states in an Oregonator model reveals a spatial symmetry breaking instability. Numerical simulations show behavior in agreement with that found experimentally and also predict a variety of other new patterns
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