1,271 research outputs found

    Research in Natural Laminar Flow and Laminar-Flow Control, part 2

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    Part 2 of the Symposium proceedings includes papers addressing various topics in basic wind tunnel research/techniques and computational transitional research. Specific topics include: advanced measurement techniques; laminar flow control; Tollmien-Schlichting wave characteristics; boundary layer transition; flow visualization; wind tunnel tests; flight tests; boundary layer equations; swept wings; and skin friction

    The isolation and Identification of Legionella Species from Environmental Sites in Rowan County, Kentucky

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    A thesis presented to the faculty of the School of Sciences and Mathematics at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Sabo E. Yakubu on December 17, 1983

    Her Life Depends On It: Sport, Physical Activity and the Health and Well-Being of American Girls

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    This report is a comprehensive compendium of research that points to physical activity and sport as fundamental solutions for many of the serious health and social problems faced by American girls. An appreciable mass of evidence-based knowledge about girls' involvement with sport and physical activity has been generated during the last decade. The amount and quality of this research are uneven and varied. For example, a good deal of research examines the associations between physical activity and risk for coronary heart disease, but studies that focus on risk for Alzheimer's disease are just beginning to issue. Researchers have verified links between high school athletic participation and teen pregnancy prevention, although more longitudinal research is needed to thoroughly confirm the connections. Overall, however, this report shows that the current state of knowledge on the relationship of physical activity to the health and social needs of American girls warrants the serious attention of public health officials, educators and sport leaders

    Her Life Depends on it III: Sport, Physical Activity and the Health and Well-being of American Girls and Women

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    Her Life Depends On It III is the Women's Sports Foundation's comprehensive report that reviews existing and emerging research on the links between participation in sport and physical activity and the health and wellbeing of American girls and women. As with the previous editions in 2004 and 2009, this study also confirms that physical activity and sport provides the critical foundation, in no small part, that allows girls and women to lead healthy, strong, and fulfilled lives. Ten years since its first publication, the updated Her Life Depends On It provides an even more comprehensive review of the ever-expanding body of research that demonstrates how important it is for girls and women to participate in sport and physical activity. The report's contents reflect the review of 1,500 studies, nearly 400 covered since the previous edition

    Compendium of NASA Langley reports on hypersonic aerodynamics

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    Reference is made to papers published by the Langley Research Center in various areas of hypersonic aerodynamics for the period 1950 to 1986. The research work was performed either in-house by the Center staff or by other personnel supported entirely or in part by grants or contracts. Abstracts have been included with the references when available. The references are listed chronologically and are grouped under the following general headings: (1) Aerodynamic Measurements - Single Shapes; (2) Aerodynamic Measurements - Configurations; (3) Aero-Heating; (4) Configuration Studies; (5) Propulsion Integration Experiment; (6) Propulsion Integration - Study; (7) Analysis Methods; (8) Test Techniques; and (9) Airframe Active Cooling Systems

    The Social Media Instructional Design Model: A New Tool for Designing Instruction Using Social Media

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    Social media is a pervasive force in the lives of 21st century learners. Social media offers a user experience that encourages students to create and share new content while enabling communication unlike any other learning technology. In this paper, we explore how learning with social media could be more effective by leveraging appropriate learning theory and instructional design. We begin with examples of how social media is currently being used in educational contexts, and then review the available research that investigates the connections between social media and education. To understand how social media may be better utilized for learning, we also identify social media’s unique learning affordances and established learning theories that complement those affordances. Finally, we present a preliminary model for designing learning using social media

    Sensitivity and Tolerance of Riparian Arthropod Communities to Altered Water Resources along a Drying River

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    Rivers around the world are drying with increasing frequency, but little is known about effects on terrestrial animal communities. Previous research along the San Pedro River in southeastern AZ, USA, suggests that changes in the availability of water resources associated with river drying lead to changes in predator abundance, community composition, diversity, and abundance of particular taxa of arthropods, but these observations have not yet been tested manipulatively

    River drying lowers the diversity and alters the composition of an assemblage of desert riparian arthropods

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    Summary 1. Many studies have shown negative effects of river drying on in‐stream animals. However, the influence of river drying on riparian animals remains poorly studied. We examined ground‐dwelling riparian arthropod assemblages along a drying section of the semi‐arid San Pedro River in southeastern Arizona, U.S.A. 2. We found strong differences in assemblage composition, taxon diversity and the abundance of key taxa between dry and flowing sites, with higher diversity and abundance of most taxa at flowing sites. 3. Changes in assemblage composition, taxon diversity and abundance of representative taxa were associated with a combined measure of water availability that included distance to water and type of water. Other environmental variables showed a weaker association with changes in these arthropod assemblages. 4. Thus, we found evidence that desert riparian arthropods are sensitive to river drying and to reduction in water resources. Increases in drying along this river may reduce the diversity and the abundance of many groups of ground‐dwelling arthropods, leading to marked shifts in community composition

    Water availability directly determines per capita consumption at two trophic levels

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    Community ecology has long focused on energy and nutrients as currencies of species interactions. Evidence from physiological ecology and recent studies suggest that in terrestrial systems, water may influence animal behavior and global patterns of species richness. Despite these observations, water has received little attention as a currency directly influencing animal species interactions. Here, we show that the per capita interaction strength between predatory wolf spiders and their primary prey, field crickets, is strong (0.266) when predators and prey are maintained in ambient dry conditions, but is near zero (0.001) when water is provided ad libitum. Moreover, crickets consume 31-fold more moist leaf material in ambient dry conditions, switching from old litter to moist green leaves when free water is scarce. Under dry conditions, animals may make foraging decisions based first on water needs, not energy or nutrients, suggesting strong and predictable effects of alterations in aridity on species interactions

    Animal water balance drives top-down effects in a riparian forest-implications for terrestrial trophic cascades

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    Despite the clear importance of water balance to the evolution of terrestrial life, much remains unknown about the effects of animal water balance on food webs. Based on recent research suggesting animal water imbalance can increase trophic interaction strengths in cages, we hypothesized that water availability could drive top-down effects in open environments, influencing the occurrence of trophic cascades. We manipulated large spider abundance and water availability in 20 × 20 m open-air plots in a streamside forest in Arizona, USA, and measured changes in cricket and small spider abundance and leaf damage. As expected, large spiders reduced both cricket abundance and herbivory under ambient, dry conditions, but not where free water was added. When water was added (free or within moist leaves), cricket abundance was unaffected by large spiders, but spiders still altered herbivory, suggesting behavioural effects. Moreover, we found threshold-type increases in herbivory at moderately low soil moisture (between 5.5% and 7% by volume), suggesting the possibility that water balance may commonly influence top-down effects. Overall, our results point towards animal water balance as an important driver of direct and indirect species interactions and food web dynamics in terrestrial ecosystems
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