4,455 research outputs found

    Aerodynamic design for improved manueverability by use of three-dimensional transonic theory

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    Improvements in transonic maneuver performance by the use of three-dimensional transonic theory and a transonic design procedure were examined. The FLO-27 code of Jameson and Caughey was used to design a new wing for a fighter configuration with lower drag at transonic maneuver conditions. The wing airfoil sections were altered to reduce the upper-surface shock strength by means of a design procedure which is based on the iterative application of the FLO-27 code. The plan form of the fighter configuration was fixed and had a leading edge sweep of 45 deg and an aspect ratio of 3.28. Wind-tunnel tests were conducted on this configuration at Mach numbers from 0.60 to 0.95 and angles of attack from -2 deg to 17 deg. The transonic maneuver performance of this configuration was evaluated by comparison with a wing designed by empirical methods and a wing designed primarily by two-dimensional transonic theory. The configuration designed by the use of FLO-27 had the same or lower drag than the empirical wing and, for some conditions, lower drag than the two-dimensional design. From some maneuver conditions, the drag of the two-dimensional design was somewhat lower

    The Utilization of Political Skill as Leverage in Sport Management Research

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    A major advancement in the political skill program of research was the development of a systematically developed and validated scale to measure political skill (i.e., referred to as the Political Skill Inventory), which reflected its four underlying dimensions of social astuteness, interpersonal influence, networking ability, and apparent sincerity. Also contributing to this expanded program of research was the publication of a comprehensive theoretical statement explaining the process dynamics and operation of the construct (Ferris et al., 2007), and also an applied book on political skill (Ferris, Davidson, & PerrewĆ©, 2005), which discussed the implications for practice of this construct, and how political skill could be trained and developed. This work also provided a specific definition of political skill as ā€œThe ability to effectively understand others at work and to use such knowledge to influence others to act in ways that enhance oneā€™s personal and/or organizational objectivesā€ (Ferris et al., 2005, p. 127). This paper examines the utility of using the political skill construct in sport research

    Finding LoTSS of hosts for GRBs: a search for galaxy - gamma-ray burst coincidences at low frequencies with LOFAR

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    The LOFAR Two-Metre Sky Survey (LoTSS) is an invaluable new tool for investigating the properties of sources at low frequencies and has helped to open up the study of galaxy populations in this regime. In this work, we perform a search for host galaxies of gamma-ray bursts (GRBs). We use the relative density of sources in Data Release 2 of LoTSS to define the probability of a chance alignment, PchanceP_{\rm chance}, and find 18 sources corresponding to 17 GRBs which meet a PchanceP_{\rm chance}<1% criterion. We examine the nature and properties of these radio sources using both LOFAR data and broadband information, including their radio spectral index, star formation rate estimates and any contributions from active galactic nucleus emission. Assuming the radio emission is dominated by star formation, we find that our sources show high star formation rates (10110^1-10310^3 MāŠ™M_{\odot} yrāˆ’1^{-1}) compared with both a field galaxy sample and a sample of core-collapse supernova hosts, and the majority of putative hosts are consistent with ultraluminous infrared galaxy (ULIRG) classifications. As a result of our analyses, we define a final sample of eight likely GRB host candidates in the LoTSS DR2 survey.Comment: 15 pages, 9 figures and 6 tables. Accepted by MNRA

    Multi-frequency fine resolution imaging radar instrumentation and data acquisition

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    Development of a dual polarized L-band radar imaging system to be used in conjunction with the present dual polarized X-band radar is described. The technique used called for heterodyning the transmitted frequency from X-band to L-band and again heterodyning the received L-band signals back to X-band for amplification, detection, and recording

    A biophysical model of prokaryotic diversity in geothermal hot springs

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    Recent field investigations of photosynthetic bacteria living in geothermal hot spring environments have revealed surprisingly complex ecosystems, with an unexpected level of genetic diversity. One case of particular interest involves the distribution along hot spring thermal gradients of genetically distinct bacterial strains that differ in their preferred temperatures for reproduction and photosynthesis. In such systems, a single variable, temperature, defines the relevant environmental variation. In spite of this, each region along the thermal gradient exhibits multiple strains of photosynthetic bacteria adapted to several distinct thermal optima, rather than the expected single thermal strain adapted to the local environmental temperature. Here we analyze microbiology data from several ecological studies to show that the thermal distribution field data exhibit several universal features independent of location and specific bacterial strain. These include the distribution of optimal temperatures of different thermal strains and the functional dependence of the net population density on temperature. Further, we present a simple population dynamics model of these systems that is highly constrained by biophysical data and by physical features of the environment. This model can explain in detail the observed diversity of different strains of the photosynthetic bacteria. It also reproduces the observed thermal population distributions, as well as certain features of population dynamics observed in laboratory studies of the same organisms

    Perceptions of alcohol health warning labels in a large international cross sectional survey of people who drink alcohol

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    Aims: This paper aimed to explore perceptions of alcohol health warning labels among a large international sample of people who drink alcohol. Methods: The Global Drug Survey (GDS) is the worldā€™s largest annual cross sectional survey of drug use. Seven health warning labels were presented (relating to heart disease, liver, cancer, calories, violence, taking two days off and the myth of benefits to moderate drinking). People were asked if they were aware of the information, believed it, if it was personally relevant, and if it would change their drinking. This paper included data from 75,969 respondents from 29 countries/regions who reported the use of alcohol in the last 12 months, collected during November-December 2017 (GDS2018). Results: The fact that drinking less can reduce the risk of seven types of cancer was the least well known, and yet was demonstrated to encourage almost 40% of drinkers to consider drinking less. Women and high risk drinkers were more likely to indicate they would reduce their drinking in response to all labels. Personal relevance was identified as a key predictor of individual responses. Conclusions: Findings highlight the potential of a range of health messages displayed on alcoholic beverages to raise awareness of alcohol related harms and potentially support a reduction in drinking. Further research should explore what influences personal relevance of messages as this may be a barrier to effectiveness

    Intention to reduce drinking alcohol and preferred sources of support: An international cross-sectional study

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    Introduction. Drinking alcohol is legal in most countries of the world. Given the social acceptance of this behavior despite potential negative impact on health, help-seeking behavior could differ when compared to other drugs. This paper aimed to assess intentions to reduce drinking and the preferred sources of support among a large international sample of people who drink alcohol. Materials and methods. The Global Drug Survey (GDS) is the worldā€™s largest annual survey of drug use. This paper included data from 82,190 respondents from 12 countries on four continents who reported the use of alcohol in the last 12 months, collected during November 2016 - January 2017 (GDS2017). Results. Overall, 34.8% said they would like to drink less in the following 12 months and 7.6% said they would like help to drink less. Online tools were the preferred source of support to reduce drinking by respondents from Australia, New Zealand, and the UK, those with low AUDIT scores and without a mental health condition. Specialist counselling was most preferred by those from Germany, Switzerland, and Denmark and those with high AUDIT scores, not educated to degree level and with a mental health condition. Conclusion. Interest in online interventions for harmful drinking is significant and highest among people who drink at low risk. Online tools should offer brief screening and feedback, ensuring that people with high risk drinking patterns are referred to more specialist services

    Coast-to-Interior Gradient in Recent Northwest Greenland Precipitation Trends (1952ā€“2012)

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    The spatial and temporal variability of precipitation on the Greenland ice sheet is an essential component of surface mass balance, which has been declining in recent years with rising temperatures. We present an analysis of precipitation trends in northwest (NW) Greenland (1952ā€“2012) using instrumental (coastal meteorological station) and proxy records (snow pits and ice cores) to characterize the precipitation gradient from the coast to the ice sheet interior. Snow-pit-derived precipitation near the coast (1950ā€“2000) has increased (~7% decadeāˆ’1, p \u3c 0.01) whereas there is no significant change observed in interior snow pits. This trend holds for 1981ā€“2012, where calculated precipitation changes decrease in magnitude with increasing distance from the coast: 13% decadeāˆ’1 (2.4 mm water equivalent (w.e.) decadeāˆ’2) at coastal Thule air base (AB), 8.6% decadeāˆ’1 (4.7 mm w.e. decadeāˆ’2) at the 2Barrel ice core site 150 km from Thule AB, āˆ’5.2% decadeāˆ’1 (1.7 mm w.e. decadeāˆ’2) at Camp Century located 205 km from Thule AB, and 4.4% decadeāˆ’1 (1.0 mm w.e. decadeāˆ’2) at B26 located 500 km from Thule AB. In general, annually averaged precipitation and annually and seasonally averaged mean air temperatures observed at Thule AB follow trends observed in composite coastal Greenland time series, with both notably indicating winter as the fastest warming season in recent periods (1981ā€“2012). Trends (1961ā€“2012) in seasonal precipitation differ, specifically with NW Greenland summer precipitation increasing (~0.6 mm w.e. decadeāˆ’2) in contrast with decreasing summer precipitation in the coastal composite time series (3.8 mm w.e. decadeāˆ’2). Differences in precipitation trends between NW Greenland and coastal composite Greenland underscore the heterogeneity in climate influences affecting precipitation. In particular, recent (1981ā€“2012) changes in NW Greenland annual precipitation are likely a response to a weakening North Atlantic oscillation
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