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

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

Internesting Movements of Loggerhead (Caretta caretta) Sea Turtles in Virginia, USA

Virginia is the northern most nesting region regularly utilized by loggerhead sea turtles (Caretta caretta) along the eastern coast of the United States. Along the southern shoreline of Virginia, between two and ten nests have been recorded annually since 1989 within Back Bay National Wildlife Refuge and False Cape State Park. Since 1992, the Virginia Institute of Marine Science (VIMS) has attached eight satellite transmitters to nesting loggerhead sea turtles in order to monitor their interesting movements and falVwinter migrations. VIMS has tracked the same nesting loggerhead three separate times during the 1993, 1995 and 1997 nesting seasons. This turtle has been observed to migrate into the Delaware Bay and Chesapeake Bay between nesting events and prior to her fall migrations. This project has demonstrated that nesting loggerhead sea turtles return to Virginia over subsequent seasons to nest, and utilize the Chesapeake and Delaware Bays as internesting and post-nesting habitat. Late season nesters tracked by VIMS have migrated south after their last recorded Virginia nesting event and have traveled along the coasts of North and South Carolina, in two cases establishing fall residency off the Carolinas. Three turtles have been tracked as far south as eastern Florida, with two entering the Gulf of Mexico before satellite transmissions ceased. The tracking data generated by this project suggest that the adult turtles utilizing Virginia as nesting habitat preferentially utilize either the orth Atlantic region or South Atlantic region as over-wintering habitat. Temperature ranges within which tagged turtles have remained range between 13° and 31 ° C. Three tagged turtles have remained in Virginia\u27s waters until sea surface temperatures dropped to between 13° and 16° C before migrating south

Visual Acuity of Juvenile Loggerhead Sea Turtles (Caretta caretta): A Behavioral Approach

Studies focusing on the visual cues sea turtles use to orient between the nesting site and the sea indicate that sea turtles use diffuse images for orientation and are highly myopic on land. The visual environment encountered by sea turtles, however, is very different in water than on land. In this study, operant conditioning techniques were used to explore the visual acuity of juvenile loggerhead sea turtles (Caretta caretta) in the marine environment. Turtles were trained, in a tank setting, to distinguish between a 45 mm striped panel and 50% gray panel by using squid as a food reward. Though the pace of training was limited by our guidelines for holding these animals in captivity and the amount of food we could give each animal in a week, all turtles were trained in under a month. Once training was achieved, the stripes were reduced in size (stripe width ranging from 45.0 – 0.035 mm) until the turtle chose the striped panel over the 50% gray panel based on chance; this level of choice was designated as threshold. Mean acuity threshold level for all turtles tested was found to be 0.078 (visual angle of 12.89 minutes of arc). These results are similar to those of other marine species and indicate that loggerhead sea turtles use distinct visual cues in the aquatic environment

Sensor to Detect Endothelialization on an Active Coronary Stent

Background A serious complication with drug-eluting coronary stents is late thrombosis, caused by exposed stent struts not covered by endothelial cells in the healing process. Real-time detection of this healing process could guide physicians for more individualized anti-platelet therapy. Here we present work towards developing a sensor to detect this healing process. Sensors on several stent struts could give information about the heterogeneity of healing across the stent. Methods A piezoelectric microcantilever was insulated with parylene and demonstrated as an endothelialization detector for incorporation within an active coronary stent. After initial characterization, endothelial cells were plated onto the cantilever surface. After they attached to the surface, they caused an increase in mass, and thus a decrease in the resonant frequencies of the cantilever. This shift was then detected electrically with an LCR meter. The self-sensing, self-actuating cantilever does not require an external, optical detection system, thus allowing for implanted applications. Results A cell density of 1300 cells/mm2 on the cantilever surface is detected. Conclusions We have developed a self-actuating, self-sensing device for detecting the presence of endothelial cells on a surface. The device is biocompatible and functions reliably in ionic liquids, making it appropriate for implantable applications. This sensor can be placed along the struts of a coronary stent to detect when the struts have been covered with a layer of endothelial cells and are no longer available surfaces for clot formation. Anti-platelet therapy can be adjusted in real-time with respect to a patient\u27s level of healing and hemorrhaging risks

Quantifying the behavioral and economic effects of regulatory change in a recreational cobia fishery

Fisheries economists typically assume recreational anglers make decisions that maximize individual angler utility, which may depend on fishery and regulatory conditions. Under this framework, changes in regulations can lead to target species substitution by anglers in response to shifts in expectations of trip utility. A stated preference survey was developed and distributed to recreational cobia (Rachycentron canadum) anglers in Virginia to explore the effects of regulatory change on angler decision-making, species targeting, and resulting economic outcomes. The survey included a series of hypothetical choice scenarios, where respondents were asked to select their most preferred alternative after being presented with different fishing trips targeting cobia,red drum (Sciaenops ocellatus), or summer flounder (Paralichthys dentatus). Seven regulatory treatments of the survey were distributed, providing anglers a variety of species targeting tradeoffs. A mixed logit model was usedto estimate angler preferences associated with hypothetical trip attributes and regulatory environment. Changes in angler welfare resulting from changes in cobia regulations were then assessed. Anglers were found to prefer targeting cobia to red drum or summer flounder under status quo management. Increases in catch, average weight of catch, and legal harvest of cobia were also found to provide anglers greater improvements in triputility compared to increases in these attributes for trips targeting red drum or summer flounder. The economic effects of regulatory change were asymmetric because restrictive regulations were found to reduce angler welfare whereas liberalizing regulations had no significant effects. Increased availability of alternative target species was found to dampen the negative welfare effects of restrictive cobia regulations due to predicted target species substitution by anglers

Devouring the Milky Way Satellites: Modeling Dwarf Galaxies with Galacticus

Dwarf galaxies are ubiquitous throughout the universe and are extremely sensitive to various forms of internal and external feedback. Over the last two decades, the census of dwarf galaxies in the Local Group and beyond has increased markedly. While hydrodynamic simulations (e.g., FIRE II, Mint Justice League) have reproduced the observed dwarf properties down to the ultrafaints, such simulations require extensive computational resources to run. In this work, we constrain the standard physical implementations in the semianalytic model Galacticus to reproduce the observed properties of the Milky Way satellites down to the ultrafaint dwarfs found in the Sloan Digital Sky Survey. We run Galacticus on merger trees from our high-resolution N-body simulation of a Milky Way analog. We determine the best-fit parameters by matching the cumulative luminosity function and luminosity-metallicity relation from both observations and hydrodynamic simulations. With the correct parameters, the standard physics in Galacticus can reproduce the observed luminosity function and luminosity-metallicity relation of the Milky Way dwarfs. In addition, we find a multidimensional match with half-light radii, velocity dispersions, and mass to light ratios at z = 0 down to M V ≤ −6 (L ≥ 104 L ⊙). In addition to successfully reproducing the properties of the z = 0 Milky Way satellite population, our modeled dwarfs have star formation histories that are consistent with those of the Local Group dwarfs

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

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