Boundary layer thickness effect on boattail drag

A combined experimental and analytical program was conducted to investigate the effects of boundary layer changes on the flow over high angle boattail nozzles. The tests were run on an isolated axisymmetric sting mounted model. Various boattail geometries were investigated at high subsonic speeds over a range of boundary layer thicknesses. In general, boundary layer effects were small at speeds up to Mach 0.8. However, at higher speeds significant regions of separated flow were present on the boattail. When separation was present large reductions in boattail drag resulted with increasing boundary layer thickness. The analysis predicts both of these trends

Using the High Productivity Language Chapel to Target GPGPU Architectures

It has been widely shown that GPGPU architectures offer large performance gains compared to their traditional CPU counterparts for many applications. The downside to these architectures is that the current programming models present numerous challenges to the programmer: lower-level languages, explicit data movement, loss of portability, and challenges in performance optimization. In this paper, we present novel methods and compiler transformations that increase productivity by enabling users to easily program GPGPU architectures using the high productivity programming language Chapel. Rather than resorting to different parallel libraries or annotations for a given parallel platform, we leverage a language that has been designed from first principles to address the challenge of programming for parallelism and locality. This also has the advantage of being portable across distinct classes of parallel architectures, including desktop multicores, distributed memory clusters, large-scale shared memory, and now CPU-GPU hybrids. We present experimental results from the Parboil benchmark suite which demonstrate that codes written in Chapel achieve performance comparable to the original versions implemented in CUDA.NSF CCF 0702260Cray Inc. Cray-SRA-2010-016962010-2011 Nvidia Research Fellowshipunpublishednot peer reviewe

Forest Diversity and Disturbance: Changing Influences and the Future of Virginia’s Forests

The Virginia landscape supports a remarkable diversity of forests, from maritime dune woodlands, swamp forests, and pine savannas of the Atlantic Coastal Plain, to post-agricultural pine-hardwood forests of the Piedmont, to mixed oak, mesophytic, northern hardwood, and high elevation spruce-fir forests across three mountain provinces in western parts of the state. Virginia’s forests also have been profoundly shaped by disturbance. Chestnut blight, hemlock woolly adelgid, emerald ash borer, and other pests have caused declines or functional extirpation of foundation species. Invasive plants like multiflora rose, Oriental bittersweet, and Japanese stiltgrass threaten both disturbed and intact forests. Oaks and other fire-dependent species have declined with prolonged fire suppression, encouraging compositional shifts to maple, beech, and other mesophytic species. Agriculture has left lasting impacts on soil and microsite variations, and atmospheric nitrogen deposition has led to soil acidification, nutrient loss, and diversity declines. Future changes associated with climate warming are expected to influence species distributions and habitat quality, particularly for hemlock-northern hardwood and spruce-fir forests. These and other disturbances will continue to shape Virginia’s forests, influencing species interactions, successional trajectories, and susceptibility to invasive plants and secondary stressors, and initiating broader impacts on forest diversity, ecosystem processes, and habitat resources for associated species and neighboring ecosystems

Measurements of winds and temperatures at altitudes up to 65 kilometers in the Southern Hemisphere

Meteorological wind, and temperature data from atmospheric radiosonde soundings in Southern Hemispher

Magnetic Miniband Structure and Quantum Oscillations in Lateral Semiconductor Superlattices

We present fully quantum-mechanical magnetotransport calculations for short-period lateral superlattices with one-dimensional electrostatic modulation. A non-perturbative treatment of both magnetic field and modulation potential proves to be necessary to reproduce novel quantum oscillations in the magnetoresistance found in recent experiments in the resistance component parallel to the modulation potential. In addition, we predict oscillations of opposite phase in the component perpendicular to the modulation not yet observed experimentally. We show that the new oscillations originate from the magnetic miniband structure in the regime of overlapping minibands.Comment: 6 pages with 4 figure

The hearing of fitness to practice cases by the General Medical Council: Current trends and future research agendas

Over the last three decades a risk-based model of medical regulation has emerged in the United Kingdom. To promote a risk-averse operational culture of transparency and professional accountability the regulatory state has intervened in medical governance and introduced best-evidenced practice frameworks, audit and performance appraisal, Against this background the paper analyses descriptive statistical data pertaining to the General Medical Council’s management of the process by which fitness to practice complaints against doctors are dealt with from initial receipt through to subsequent investigative and adjudication stages. Statistical trends are outlined regarding complaint data in relation to a doctor’s gender and race and ethnicity. The data shows that there has been an increase in rehabilitative and/or punitive action against doctors. In light of its findings the paper considers what the long-term consequences may be, for both patients and doctors, of the increasing use of risk-averse administrative systems to reform medical regulation and ensure professional accountability

Constraints on the Intergalactic Transport of Cosmic Rays

Motivated by recent experimental proposals to search for extragalactic cosmic rays (including anti-matter from distant galaxies), we study particle propagation through the intergalactic medium (IGM). We first use estimates of the magnetic field strength between galaxies to constrain the mean free path for diffusion of particles through the IGM. We then develop a simple analytic model to describe the diffusion of cosmic rays. Given the current age of galaxies, our results indicate that, in reasonable models, a completely negligible number of particles can enter our Galaxy from distances greater than $\sim 100$ Mpc for relatively low energies ($E$ $< 10^6$ GeV/n). We also find that particle destruction in galaxies along the diffusion path produces an exponential suppression of the possible flux of extragalactic cosmic rays. Finally, we use gamma ray constraints to argue that the distance to any hypothetical domains of anti-matter must be roughly comparable to the horizon scale.Comment: 24 pages, AAS LaTex, 1 figure, accepted to Ap

Immune Responses to rAAV6: The Influence of Canine Parvovirus Vaccination and Neonatal Administration of Viral Vector

Recombinant adeno-associated viral (rAAV) vectors promote long-term gene transfer in many animal species. Significant effort has focused on the evaluation of rAAV delivery and the immune response in both murine and canine models of neuromuscular disease. However, canines provided for research purposes are routinely vaccinated against canine parvovirus (CPV). rAAV and CPV possess significant homology and are both parvoviruses. Thus, any immune response generated to CPV vaccination has the potential to cross-react with rAAV vectors. In this study, we investigated the immune response to rAAV6 delivery in a cohort of CPV-vaccinated canines and evaluated multiple vaccination regimens in a mouse model of CPV-vaccination. We show that CPV-vaccination stimulates production of neutralizing antibodies with minimal cross-reactivity to rAAV6. In addition, no significant differences were observed in the magnitude of the rAAV6-directed immune response between CPV-vaccinated animals and controls. Moreover, CPV-vaccination did not inhibit rAAV6-mediated transduction. We also evaluated the immune response to early rAAV6-vaccination in neonatal mice. The influence of maternal hormones and cytokines leads to a relatively permissive state in the neonate. We hypothesized that immaturity of the immune system would permit induction of tolerance to rAAV6 when delivered during the neonatal period. Mice were vaccinated with rAAV6 at 1 or 5 days of age, and subsequently challenged with rAAV6 exposure during adulthood via two sequential IM injections, 1 month apart. All vaccinated animals generated a significant neutralizing antibody response to rAAV6-vaccination that was enhanced following IM injection in adulthood. Taken together, these data demonstrate that the immune response raised against rAAV6 is distinct from that which is elicited by the standard parvoviral vaccines and is sufficient to prevent stable tolerization in neonatal mice

Selection of landcover types by translocated female eastern wild turkeys in east Texas

Restoration of eastern wild turkeys (Meleagris gallopavo silvestris) is among the greatest conservation achievements in North America. However, restoration efforts in east Texas have had limited success, resulting in a fragmented distribution of turkeys across the landscape. Restoration success is largely dependent on the ability of translocated individuals to quickly select habitat patches on the landscape. Information on habitat selection of translocated wild turkeys is important to identify high quality release locations that should reduce the probability of translocation failure. Our objective was to describe selection of landcover types by translocated female wild turkeys in east Texas. During 2016–2017, we translocated 78 GPS‐tagged wild turkeys to Angelina National Forest in east Texas. We quantified third order selection for females during 3 temporal periods—the exploratory phase (days 1–20), the exploitation phase (days 21–80), and within the annual range. During the exploratory phase, females selected shrub‐scrub and open landcover types, as well as linear paths (roads, rights-of‐way). During the exploitation phase, females selected shrub-scrub, mixed, and open landcover types, but not linear paths. Overall, wild turkeys translocated into forested landscapes of east Texas selected for early successional and other open landcover types. Prior to translocation attempts in forest-dominated landscapes, managers should consider ways to increase availability of open landcover types with herbaceous cover for nesting and brood rearing