788 research outputs found

    Method to predict external store carriage loads at transonic speeds

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    A computational method for prediction of external store carriage loads at transonic speeds is described. The geometric flexibility required for treatment of isolated and underwing, pylon mounted stores is achieved by computing solutions on a five level embedded grid arrangement. A completely automated grid generation procedure facilitates applications. Store modeling capability consists of bodies of revolution with multiple fore and aft fins. A body conforming grid improves the accuracy of the computed store body flow field. A nonlinear finite difference relaxation scheme, developed specifically for modified transonic small disturbance flow equations, enhances numerical stability and accuracy. As a result, more accurate treatment of low aspect ratio, highly swept and tapered wing planforms is possible. A limited supersonic freestream capability is also provided. Pressure, load distribution, force and moment correlation show good agreement for several test cases

    Method to predict external store carriage characteristics at transonic speeds

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    Development of a computational method for prediction of external store carriage characteristics at transonic speeds is described. The geometric flexibility required for treatment of pylon-mounted stores is achieved by computing finite difference solutions on a five-level embedded grid arrangement. A completely automated grid generation procedure facilitates applications. Store modeling capability consists of bodies of revolution with multiple fore and aft fins. A body-conforming grid improves the accuracy of the computed store body flow field. A nonlinear relaxation scheme developed specifically for modified transonic small disturbance flow equations enhances the method's numerical stability and accuracy. As a result, treatment of lower aspect ratio, more highly swept and tapered wings is possible. A limited supersonic freestream capability is also provided. Pressure, load distribution, and force/moment correlations show good agreement with experimental data for several test cases. A detailed computer program description for the Transonic Store Carriage Loads Prediction (TSCLP) Code is included

    Uncertainty Estimation using the Local Lipschitz for Deep Learning Image Reconstruction Models

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    The use of supervised deep neural network approaches has been investigated to solve inverse problems in all domains, especially radiology where imaging technologies are at the heart of diagnostics. However, in deployment, these models are exposed to input distributions that are widely shifted from training data, due in part to data biases or drifts. It becomes crucial to know whether a given input lies outside the training data distribution before relying on the reconstruction for diagnosis. The goal of this work is three-fold: (i) demonstrate use of the local Lipshitz value as an uncertainty estimation threshold for determining suitable performance, (ii) provide method for identifying out-of-distribution (OOD) images where the model may not have generalized, and (iii) use the local Lipschitz values to guide proper data augmentation through identifying false positives and decrease epistemic uncertainty. We provide results for both MRI reconstruction and CT sparse view to full view reconstruction using AUTOMAP and UNET architectures due to it being pertinent in the medical domain that reconstructed images remain diagnostically accurate

    Economic Outcomes of Patients Receiving Antiretroviral Therapy for HIV/AIDS in South Africa Are Sustained through Three Years on Treatment

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    BACKGROUND. Although the medical outcomes of antiretroviral therapy (ART) for HIV/AIDS are well described, less is known about how ART affects patients' economic activities and quality of life, especially after the first year on ART. We assessed symptom prevalence, general health, ability to perform normal activities, and employment status among adult antiretroviral therapy patients in South Africa over three full years following ART initiation. METHODOLOGY/PRINCIPAL FINDINGS. A cohort of 855 adult pre-ART patients and patients on ART for <6 months was enrolled and interviewed an average of 4.4 times each during routine clinic visits for up to three years after treatment initiation using an instrument designed for the study. The probability of pain in the previous week fell from 74% before ART initiation to 32% after three years on ART, fatigue from 66% to 12%, nausea from 28% to 4%, and skin problems from 55% to 10%. The probability of not feeling well physically yesterday fell from 46% to 23%. Before starting ART, 39% of subjects reported not being able to perform their normal activities sometime during the previous week; after three years, this proportion fell to 10%. Employment rose from 27% to 42% of the cohort. Improvement in all outcomes was sustained over 3 years and for some outcomes increased in the second and third year. CONCLUSIONS/SIGNIFICANCE. Improvements in adult ART patients' symptom prevalence, general health, ability to perform normal activities, and employment status were large and were sustained through the first three years on treatment. These results suggest that some of the positive economic and social externalities anticipated as a result of large-scale treatment provision, such as increases in workforce participation and productivity and the ability of patients to carry on normal lives, may indeed be accruing.South Africa Mission of the U.S. Agency for International Development (GHSA-00-00020-00, 674-A-00-09-00018-00, 674-A-00-02-00018); National Institute of Allergies and Infectious Diseases (PEPFAR 13, K01AI083097); APDA Advanced Center for Parkinson Research at UAB (NIH F30NS065661, NIH R01CA122930); National Institutes of Health Blueprint Core for Neuroscience Research (NS057098

    Retention in care, resource utilization, and costs for adults receiving antiretroviral therapy in Zambia: a retrospective cohort study

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    BACKGROUND: Of the estimated 800,000 adults living with HIV in Zambia in 2011, roughly half were receiving antiretroviral therapy (ART). As treatment scale up continues, information on the care provided to patients after initiating ART can help guide decision-making. We estimated retention in care, the quantity of resources utilized, and costs for a retrospective cohort of adults initiating ART under routine clinical conditions in Zambia. METHODS: Data on resource utilization (antiretroviral [ARV] and non-ARV drugs, laboratory tests, outpatient clinic visits, and fixed resources) and retention in care were extracted from medical records for 846 patients who initiated ART at ≥15 years of age at six treatment sites between July 2007 and October 2008. Unit costs were estimated from the provider’s perspective using site- and country-level data and are reported in 2011 USD. RESULTS: Patients initiated ART at a median CD4 cell count of 145 cells/μL. Fifty-nine percent of patients initiated on a tenofovir-containing regimen, ranging from 15% to 86% depending on site. One year after ART initiation, 75% of patients were retained in care. The average cost per patient retained in care one year after ART initiation was 243(95243 (95% CI, 194-293),rangingfrom293), ranging from 184 (95% CI, 172−172-195) to 304(95304 (95% CI, 290-$319) depending on site. Patients retained in care one year after ART initiation received, on average, 11.4 months’ worth of ARV drugs, 1.5 CD4 tests, 1.3 blood chemistry tests, 1.4 full blood count tests, and 6.5 clinic visits with a doctor or clinical officer. At all sites, ARV drugs were the largest cost component, ranging from 38% to 84% of total costs, depending on site. CONCLUSIONS: Patients initiate ART late in the course of disease progression and a large proportion drop out of care after initiation. The quantity of resources utilized and costs vary widely by site, and patients utilize a different mix of resources under routine clinical conditions than if they were receiving fully guideline-concordant care. Improving retention in care and guideline concordance, including increasing the use of tenofovir in first-line ART regimens, may lead to increases in overall treatment costs

    Peripheral Innate Immune Activation Correlates With Disease Severity in GRN Haploinsufficiency.

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    Objective: To investigate associations between peripheral innate immune activation and frontotemporal lobar degeneration (FTLD) in progranulin gene (GRN) haploinsufficiency. Methods: In this cross-sectional study, ELISA was used to measure six markers of innate immunity (sCD163, CCL18, LBP, sCD14, IL-18, and CRP) in plasma from 30 GRN mutation carriers (17 asymptomatic, 13 symptomatic) and 29 controls. Voxel based morphometry was used to model associations between marker levels and brain atrophy in mutation carriers relative to controls. Linear regression was used to model relationships between plasma marker levels with mean frontal white matter integrity [fractional anisotropy (FA)] and the FTLD modified Clinical Dementia Rating Scale sum of boxes score (FTLD-CDR SB). Results: Plasma sCD163 was higher in symptomatic GRN carriers [mean 321 ng/ml (SD 125)] compared to controls [mean 248 ng/ml (SD 58); p &lt; 0.05]. Plasma CCL18 was higher in symptomatic GRN carriers [mean 56.9 pg/ml (SD 19)] compared to controls [mean 40.5 pg/ml (SD 14); p &lt; 0.05]. Elevation of plasma LBP was associated with white matter atrophy in the right frontal pole and left inferior frontal gyrus (p FWE corrected &lt;0.05) in all mutation carriers relative to controls. Plasma LBP levels inversely correlated with bilateral frontal white matter FA (R2 = 0.59, p = 0.009) in mutation carriers. Elevation in plasma was positively correlated with CDR-FTLD SB (b = 2.27 CDR units/μg LBP/ml plasma, R2 = 0.76, p = 0.003) in symptomatic carriers. Conclusion: FTLD-GRN is associated with elevations in peripheral biomarkers of macrophage-mediated innate immunity, including sCD163 and CCL18. Clinical disease severity and white matter integrity are correlated with blood LBP, suggesting a role for peripheral immune activation in FTLD-GRN

    Damage to left frontal regulatory circuits produces greater positive emotional reactivity in frontotemporal dementia.

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    Positive emotions foster social relationships and motivate thought and action. Dysregulation of positive emotion may give rise to debilitating clinical symptomatology such as mania, risk-taking, and disinhibition. Neuroanatomically, there is extensive evidence that the left hemisphere of the brain, and the left frontal lobe in particular, plays an important role in positive emotion generation. Although prior studies have found that left frontal injury decreases positive emotion, it is not clear whether selective damage to left frontal emotion regulatory systems can actually increase positive emotion. We measured happiness reactivity in 96 patients with frontotemporal dementia (FTD), a neurodegenerative disease that targets emotion-relevant neural systems and causes alterations in positive emotion (i.e., euphoria and jocularity), and in 34 healthy controls. Participants watched a film clip designed to elicit happiness and a comparison film clip designed to elicit sadness while their facial behavior, physiological reactivity, and self-reported emotional experience were monitored. Whole-brain voxel-based morphometry (VBM) analyses revealed that atrophy in predominantly left hemisphere fronto-striatal emotion regulation systems including left ventrolateral prefrontal cortex, orbitofrontal cortex, anterior insula, and striatum was associated with greater happiness facial behavior during the film (pFWE &lt; .05). Atrophy in left anterior insula and bilateral frontopolar cortex was also associated with higher cardiovascular reactivity (i.e., heart rate and blood pressure) but not self-reported positive emotional experience during the happy film (p &lt; .005, uncorrected). No regions emerged as being associated with greater sadness reactivity, which suggests that left-lateralized fronto-striatal atrophy is selectively associated with happiness dysregulation. Whereas previous models have proposed that left frontal injury decreases positive emotional responding, we argue that selective disruption of left hemisphere emotion regulating systems can impair the ability to suppress positive emotions such as happiness
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