301 research outputs found

    Simulations of the NASA Langley 14- by 22-Foot Subsonic Tunnel for the Juncture Flow Experiment

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    NASAs Transformational Tools and Technologies Programs Juncture Flow experiment aims to provide data to improve Computational Fluid Dynamics (CFD) modeling in the juncture flow region. The experiment is planned to provide validation-quality data for CFD that focuses on the separation bubble near the wing-body juncture trailing edge region. Because wind tunnel tests associated with the Juncture Flow project have been designed for the purpose of CFD validation, considerable effort is going into modeling and simulating the wind tunnel. This is not only important because wind tunnel wall effects can play a role in integrated testing uncertainties, but also because the better the boundary conditions are known, the better CFD can accurately represent the experiment. This paper builds on the recent CFD efforts to model the NASA Langley 14- by 22-Foot Subsonic Tunnel. Current best practices in simulating wind tunnels are evaluated. The features of each method, as well as some of their pros and cons, are highlighted. Boundary conditions and modeling techniques currently used by CFD for empty-tunnel simulations are also described. Preliminary CFD studies associated with modeling the Juncture Flow model are summarized, with the intention to determine sensitivities of the flow near the wing-body juncture region of the model to a variety of modeling decisions

    Effect of Turbulence Modeling on Hovering Rotor Flows

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    The effect of turbulence models in the off-body grids on the accuracy of solutions for rotor flows in hover has been investigated. Results from the Reynolds-Averaged Navier-Stokes and Laminar Off-Body models are compared. Advection of turbulent eddy viscosity has been studied to find the mechanism leading to inaccurate solutions. A coaxial rotor result is also included

    Drag Prediction for the NASA CRM Wing-Body-Tail Using CFL3D and OVERFLOW on an Overset Mesh

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    In response to the fourth AIAA CFD Drag Prediction Workshop (DPW-IV), the NASA Common Research Model (CRM) wing-body and wing-body-tail configurations are analyzed using the Reynolds-averaged Navier-Stokes (RANS) flow solvers CFL3D and OVERFLOW. Two families of structured, overset grids are built for DPW-IV. Grid Family 1 (GF1) consists of a coarse (7.2 million), medium (16.9 million), fine (56.5 million), and extra-fine (189.4 million) mesh. Grid Family 2 (GF2) is an extension of the first and includes a superfine (714.2 million) and an ultra-fine (2.4 billion) mesh. The medium grid anchors both families with an established build process for accurate cruise drag prediction studies. This base mesh is coarsened and enhanced to form a set of parametrically equivalent grids that increase in size by a factor of roughly 3.4 from one level to the next denser level. Both CFL3D and OVERFLOW are run on GF1 using a consistent numerical approach. Additional OVERFLOW runs are made to study effects of differencing scheme and turbulence model on GF1 and to obtain results for GF2. All CFD results are post-processed using Richardson extrapolation, and approximate grid-converged values of drag are compared. The medium grid is also used to compute a trimmed drag polar for both codes

    Projected impact of dengue vaccination in YucatĂĄn, Mexico

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    Dengue vaccines will soon provide a new tool for reducing dengue disease, but the effectiveness of widespread vaccination campaigns has not yet been determined. We developed an agent-based dengue model representing movement of and transmission dynamics among people and mosquitoes in YucatĂĄn, Mexico, and simulated various vaccine scenarios to evaluate effectiveness under those conditions. This model includes detailed spatial representation of the YucatĂĄn population, including the location and movement of 1.8 million people between 375,000 households and 100,000 workplaces and schools. Where possible, we designed the model to use data sources with international coverage, to simplify re-parameterization for other regions. The simulation and analysis integrate 35 years of mild and severe case data (including dengue serotype when available), results of a seroprevalence survey, satellite imagery, and climatological, census, and economic data. To fit model parameters that are not directly informed by available data, such as disease reporting rates and dengue transmission parameters, we developed a parameter estimation toolkit called AbcSmc, which we have made publicly available. After fitting the simulation model to dengue case data, we forecasted transmission and assessed the relative effectiveness of several vaccination strategies over a 20 year period. Vaccine efficacy is based on phase III trial results for the Sanofi-Pasteur vaccine, Dengvaxia. We consider routine vaccination of 2, 9, or 16 year-olds, with and without a one-time catch-up campaign to age 30. Because the durability of Dengvaxia is not yet established, we consider hypothetical vaccines that confer either durable or waning immunity, and we evaluate the use of booster doses to counter waning. We find that plausible vaccination scenarios with a durable vaccine reduce annual dengue incidence by as much as 80% within five years. However, if vaccine efficacy wanes after administration, we find that there can be years with larger epidemics than would occur without any vaccination, and that vaccine booster doses are necessary to prevent this outcome

    Systemic ablation of Camkk2 impairs metastatic colonization and improves insulin sensitivity in TRAMP mice : Evidence for cancer cell-extrinsic CAMKK2 functions in prostate cancer

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    Despite early studies linking calcium-calmodulin protein kinase kinase 2 (CAMKK2) to prostate cancer cell migration and invasion, the role of CAMKK2 in metastasis in vivo remains unclear. Moreover, while CAMKK2 is known to regulate systemic metabolism, whether CAMKK2’s effects on whole-body metabolism would impact prostate cancer progression and/or related comorbidities is not known. Here, we demonstrate that germline ablation of Camkk2 slows, but does not stop, primary prostate tumorigenesis in the TRansgenic Adenocarcinoma Mouse Prostate (TRAMP) genetic mouse model. Consistent with prior epidemiological reports supporting a link between obesity and prostate cancer aggressiveness, TRAMP mice fed a high-fat diet exhibited a pronounced increase in the colonization of lung metastases. We demonstrated that this effect on the metastatic spread was dependent on CAMKK2. Notably, diet-induced lung metastases exhibited a highly aggressive neuroendocrine phenotype. Concurrently, Camkk2 deletion improved insulin sensitivity in the same mice. Histological analyses revealed that cancer cells were smaller in the TRAMP;Camkk2−/− mice compared to TRAMP;Camkk2+/+ controls. Given the differences in circulating insulin levels, a known regulator of cell growth, we hypothesized that systemic CAMKK2 could promote prostate cancer cell growth and disease progression in part through cancer cell-extrinsic mechanisms. Accordingly, host deletion of Camkk2 impaired the growth of syngeneic murine prostate tumors in vivo, confirming nonautonomous roles for CAMKK2 in prostate cancer. Cancer cell size and mTOR signaling was diminished in tumors propagated in Camkk2-null mice. Together, these data indicate that, in addition to cancer cell-intrinsic roles, CAMKK2 mediates prostate cancer progression via tumor-extrinsic mechanisms. Further, we propose that CAMKK2 inhibition may also help combat common metabolic comorbidities in men with advanced prostate cancer

    Perceived Discrimination and Adherence to Medical Care in a Racially Integrated Community

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    BACKGROUND: Past research indicates that access to health care and utilization of services varies by sociodemographic characteristics, but little is known about racial differences in health care utilization within racially integrated communities. OBJECTIVE: To determine whether perceived discrimination was associated with delays in seeking medical care and adherence to medical care recommendations among African Americans and whites living in a socioeconomically homogenous and racially integrated community. DESIGN: A cross-sectional analysis from the Exploring Health Disparities in Integrated Communities Study. PARTICIPANTS: Study participants include 1,408 African-American (59.3%) and white (40.7%) adults (≄18 years) in Baltimore, Md. MEASUREMENTS: An interviewer-administered questionnaire was used to assess the associations of perceived discrimination with help-seeking behavior for and adherence to medical care. RESULTS: For both African Americans and whites, a report of 1–2 and >2 discrimination experiences in one’s lifetime were associated with more medical care delays and nonadherence compared to those with no experiences after adjustment for need, enabling, and predisposing factors (odds ratio [OR] = 1.8, 2.6; OR = 2.2, 3.3, respectively; all P < .05). Results were similar for perceived discrimination occurring in the past year. CONCLUSIONS: Experiences with discrimination were associated with delays in seeking medical care and poor adherence to medical care recommendations INDEPENDENT OF NEED, ENABLING, AND PREDISPOSING FACTORS, INCLUDING MEDICAL MISTRUST; however, a prospective study is needed. Further research in this area should include exploration of other potential mechanisms for the association between perceived discrimination and health service utilization

    Garden and landscape-scale correlates of moths of differing conservation status: significant effects of urbanization and habitat diversity

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    Moths are abundant and ubiquitous in vegetated terrestrial environments and are pollinators, important herbivores of wild plants, and food for birds, bats and rodents. In recent years, many once abundant and widespread species have shown sharp declines that have been cited by some as indicative of a widespread insect biodiversity crisis. Likely causes of these declines include agricultural intensification, light pollution, climate change, and urbanization; however, the real underlying cause(s) is still open to conjecture. We used data collected from the citizen science Garden Moth Scheme (GMS) to explore the spatial association between the abundance of 195 widespread British species of moth, and garden habitat and landscape features, to see if spatial habitat and landscape associations varied for species of differing conservation status. We found that associations with habitat and landscape composition were species-specific, but that there were consistent trends in species richness and total moth abundance. Gardens with more diverse and extensive microhabitats were associated with higher species richness and moth abundance; gardens near to the coast were associated with higher richness and moth abundance; and gardens in more urbanized locations were associated with lower species richness and moth abundance. The same trends were also found for species classified as increasing, declining and vulnerable under IUCN (World Conservation Union) criteria

    Global NeuroAIDS Roundtable

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    In May 2012, the Division of AIDS Research at the National Institute of Mental Health (NIMH) organized the “Global NeuroAIDS Roundtable” in conjunction with the 11th International Symposium on Neurovirology and the 2012 Conference on HIV in the Nervous System. The meeting was held in New York, NY, USA and brought together NIMH-funded investigators who are currently working on projects related to the neurological complications of AIDS (NeuroAIDS) in Africa, Asia, Eastern Europe, and Latin America in order to provide an opportunity to share their recent findings and discuss the challenges encountered within each country. The major goals of the roundtable were to evaluate HIV-associated neurocognitive impairment and determine if it may be directly attributable to distinct HIV subtypes or clades and to discuss the future priorities for global NeuroAIDS research. At the “Global NeuroAIDS Roundtable”, presentations of preliminary research indicated that HIV-associated neurocognitive impairment is prevalent in all countries examined regardless of which HIV clade is present in the region. The only clear-cut difference between HIV-1 clades was in relation to subtypes A and D in Uganda. However, a key point that emerged from the discussions was that there is an urgent need to standardize neurocognitive assessment methodologies across the globe before definitive conclusions can be drawn regarding the relationship between HIV clade diversity and neuropathogenesis. Future research directions were also discussed at the roundtable with particular emphasis on the potential of viral and host factor molecular interactions to impact the pathophysiology of HIV-associated neurocognitive disorders (HAND) from a global perspective

    Improved Limits on B0B^{0} decays to invisible (+Îł)(+\gamma) final states

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    We establish improved upper limits on branching fractions for B0 decays to final States 10 where the decay products are purely invisible (i.e., no observable final state particles) and for final states where the only visible product is a photon. Within the Standard Model, these decays have branching fractions that are below the current experimental sensitivity, but various models of physics beyond the Standard Model predict significant contributions for these channels. Using 471 million BB pairs collected at the Y(4S) resonance by the BABAR experiment at the PEP-II e+e- storage ring at the SLAC National Accelerator Laboratory, we establish upper limits at the 90% confidence level of 2.4x10^-5 for the branching fraction of B0-->Invisible and 1.7x10^-5 for the branching fraction of B0-->Invisible+gammaComment: 8 pages, 3 postscript figures, submitted to Phys. Rev. D (Rapid Communications

    Evidence for the h_b(1P) meson in the decay Upsilon(3S) --> pi0 h_b(1P)

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    Using a sample of 122 million Upsilon(3S) events recorded with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we search for the hb(1P)h_b(1P) spin-singlet partner of the P-wave chi_{bJ}(1P) states in the sequential decay Upsilon(3S) --> pi0 h_b(1P), h_b(1P) --> gamma eta_b(1S). We observe an excess of events above background in the distribution of the recoil mass against the pi0 at mass 9902 +/- 4(stat.) +/- 2(syst.) MeV/c^2. The width of the observed signal is consistent with experimental resolution, and its significance is 3.1sigma, including systematic uncertainties. We obtain the value (4.3 +/- 1.1(stat.) +/- 0.9(syst.)) x 10^{-4} for the product branching fraction BF(Upsilon(3S)-->pi0 h_b) x BF(h_b-->gamma eta_b).Comment: 8 pages, 4 postscript figures, submitted to Phys. Rev. D (Rapid Communications
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