Wind erosion in semiarid landscapes: Predictive models and remote sensing methods for the influence of vegetation

Wind erosion in semi-arid regions is a significant problem for which the sheltering effect of rangeland vegetation is poorly understood. Individual plants may be considered as porous roughness elements which absorb or redistribute the wind's momentum. The saltation threshold is the minimum wind velocity at which soil movement begins. The dependence of the saltation threshold on geometrical parameters of a uniform roughness array was studied in a wind tunnel. Both solid and porous elements were used to determine relationships between canopy structure and the threshold velocity for soil transport. The development of a predictive relation for the influence of vegetation canopy structure on wind erosion of soil is discussed

Highly migratory shark fisheries research by the National Shark Research Consortium (NSRC), 2002-2007

The National Shark Research Consortium (NSRC) includes the Center for Shark Research at Mote Marine Laboratory, the Pacific Shark Research Center at Moss Landing Marine Laboratories, the Shark Research Program at the Virginia Institute of Marine Science, and the Florida Program for Shark Research at the University of Florida. The consortium objectives include shark-related research in the Gulf of Mexico and along the Atlantic and Pacific coasts of the U.S., education and scientific cooperation

Viewpoint: A Pragmatic Approach to Constructing a Minimum Data Set for Care of Patients with HIV in Developing Countries

Providing quality health care requires access to continuous patient data that developing countries often lack. A panel of medical informatics specialists, clinical human immunodeficiency virus (HIV) specialists, and program managers suggests a minimum data set for supporting the management and monitoring of patients with HIV and their care programs in developing countries. The proposed minimum data set consists of data for registration and scheduling, monitoring and improving practice management, and describing clinical encounters and clinical care. Data should be numeric or coded using standard definitions and minimal free text. To enhance accuracy, efficiency, and availability, data should be recorded electronically by those generating them. Data elements must be sufficiently detailed to support clinical algorithms/guidelines and aggregation into broader categories for consumption by higher level users (e.g., national and international health care agencies). The proposed minimum data set will evolve over time as funding increases, care protocols change, and additional tests and treatments become available for HIV-infected patients in developing countrie

Social and cultural origins of motivations to volunteer a comparison of university students in six countries

Although participation in volunteering and motivations to volunteer (MTV) have received substantial attention on the national level, particularly in the US, few studies have compared and explained these issues across cultural and political contexts. This study compares how two theoretical perspectives, social origins theory and signalling theory, explain variations in MTV across different countries. The study analyses responses from a sample of 5794 students from six countries representing distinct institutional contexts. The findings provide strong support for signalling theory but less so for social origins theory. The article concludes that volunteering is a personal decision and thus is influenced more at the individual level but is also impacted to some degree by macro-level societal forces

Time to First-Line ART Failure and Time to Second-Line ART Switch in the IeDEA Pediatric Cohort

BACKGROUND: Globally, 49% of the estimated 1.8 million children living with HIV are accessing antiretroviral therapy (ART). There are limited data concerning long-term durability of first-line ART regimens and time to transition to second-line. METHODS: Children initiating their first ART regimen between 2 and 14 years of age and enrolled in one of 208 sites in 30 Asia-Pacific and African countries participating in the Pediatric International Epidemiology Databases to Evaluate AIDS consortium were included in this analysis. Outcomes of interest were: first-line ART failure (clinical, immunologic, or virologic), change to second-line, and attrition (death or loss to program ). Cumulative incidence was computed for first-line failure and second-line initiation, with attrition as a competing event. RESULTS: In 27,031 children, median age at ART initiation was 6.7 years. Median baseline CD4% for children ≤5 years of age was 13.2% and CD4 count for those >5 years was 258 cells per microliter. Almost all (94.4%) initiated a nonnucleoside reverse transcriptase inhibitor; 5.3% a protease inhibitor, and 0.3% a triple nucleoside reverse transcriptase inhibitor-based regimen. At 1 year, 7.7% had failed and 14.4% had experienced attrition; by 5 years, the cumulative incidence was 25.9% and 29.4%, respectively. At 1 year after ART failure, 13.7% had transitioned to second-line and 11.2% had experienced attrition; by 5 years, the cumulative incidence was 31.6% and 25.9%, respectively. CONCLUSIONS: High rates of first-line failure and attrition were identified in children within 5 years after ART initiation. Of children meeting failure criteria, only one-third were transitioned to second-line ART within 5 years

Intraspecific Variation in Vertical Habitat Use by Tiger Sharks (Galeocerdo cuvier) in the Western North Atlantic

Tiger sharks (Galeocerdo cuvier) are a wide ranging, potentially keystone predator species that display a variety of horizontal movement patterns, making use of coastal and pelagic waters. Far less, however, is known about their vertical movements and use of the water column. We used pop-up satellite archival tags with two data sampling rates (high rate and standard rate tags) to investigate the vertical habitat use and diving behavior of tiger sharks tagged on the Puerto Rico–Virgin Islands platform and off Bermuda between 2008 and 2009. Useable data were received from nine of 14 sharks tagged, tracked over a total of 529 days. Sharks spent the majority of their time making yo-yo dives within the upper 50 m of the water column and considerable time within the upper 5 m of the water column. As a result, sharks typically occupied a narrow daily temperature range (~2°C). Dives to greater than 200 m were common, and all sharks made dives to at least 250 m, with one shark reaching a depth of 828 m. Despite some similarities among individuals, a great deal of intraspecific variability in vertical habit use was observed. Four distinct depth distributions that were not related to tagging location, horizontal movements, sex, or size were detected. In addition, similar depth distributions did not necessitate similar dive patterns among sharks. Recognition of intraspecific variability in habitat use of top predators can be crucial for effective management of these species and for understanding their influence on ecosystem dynamics

Fertility, Living Arrangements, Care and Mobility

There are four main interconnecting themes around which the contributions in this book are based. This introductory chapter aims to establish the broad context for the chapters that follow by discussing each of the themes. It does so by setting these themes within the overarching demographic challenge of the twenty-first century – demographic ageing. Each chapter is introduced in the context of the specific theme to which it primarily relates and there is a summary of the data sets used by the contributors to illustrate the wide range of cross-sectional and longitudinal data analysed

Happy to help? Exploring the factors associated with variations in rates of volunteering across Europe

The frequency of formal volunteering varies widely across European countries, and rates of formal volunteering are especially low among Eastern European countries. Why are there such large differences in volunteering rates when it is known that volunteering is beneficial for well-being? Using data from the latest round of the European Social Survey, we test three hypotheses to explain these cross-national differences in volunteering. We ask whether people in countries with low frequencies of volunteering spend more of their time on informal volunteering activities; whether they differ on socio-demographic variables which are known to be linked to volunteering rates; or whether they show less well-being benefit from formal volunteering. Contrary to the first hypothesis, we find a positive correlation between formal and informal volunteering. We further conclude that national differences in rates of volunteering cannot be fully explained by differences in the social, psychological or cultural factors associated with volunteering nor the outcome of volunteering. It is likely that contextual factors, such as a country’s historical background or institutions, determine levels of volunteering to a large extent

AN INTEGRATED METHOD TO OBTAIN THREE-DIMENSIONAL COORDINATES USING PANNING AND TILTING VIDEO CAMERAS

Kinematic measurements of sports performances have generally been gathered using stationary cameras. Many activities, however, cover dimensions that are much larger than the athlete, resulting in measures that are less accurate than desired. One solution is to increase the resolution of the acquisition equipment. Hardware providing sufficient resolution, if possible to find, may be prohibitively expensive. Another solution is to use rotating cameras to follow the athlete’s movements. Until now, this procedure demanded time-consuming calibrations and expensive, specialized equipment. An efficient, accurate, and inexpensive method was developed to quantify threedimensional motion from rotating video cameras. The procedure uses two 20,000 count/revolution optical encoders embedded in specially machined tripod heads to sense the angular positions of the cameras. One encoder is aligned vertically to measure pan positions, while the other is aligned horizontally to measure tilt. The pan and tilt angles are printed on each video image by an interface unit. The images are then recorded on videotape and imported into a computer using a commercial frame grabber. Locations on the body may be identified manually or automatically if markers are placed on the athlete. As the points are tracked, the pan and tilt angles are decoded and stored with the digitized data. Custom software modules use these data to compute the 3D coordinates via ray-tracing techniques. Calibration, conducted before or after the performance, requires three to nine vertical rods of known length placed near the volume of interest. No on-site measurements or background markers are needed. Furthermore, calibration does not restrict camera positioning; the locations depend upon the focal length of the camera lenses, the resolution of the encoders, the shape of the movement volume, and the speed of the athlete. Dynamic accuracy was measured by moving a 0.900 m long rod through a 2 m x 4 m x 15 m volume while sampling from two 60 Hz video cameras. Nine hundred images were analyzed. The endpoints of the rod were digitized and its length computed for each video image. The mean length of the rod was 0.891 m and the Root Mean Square Error was 0.005 m. These measures compared better than other reported methods. Applications have ranged from multi-stride running in the laboratory or on a track, long jumping, high jumping, gymnastics, pole vaulting, and ski jumping