3,452 research outputs found

    Paper Session I-A - Unmanned Aerial Vehicles as Technology Demonstrators for Advanced Range Systems

    Get PDF
    This project consists of the development and operation of an unmanned aerial vehicle (UAV) as a technology demonstration test bed for advanced range systems under development at Kennedy Space Center. The goal is to acquire a reliable, rapidly accessible vehicle for initial flight testing of electronic payloads through a limited portion of airspace to verify basic communications, command and control, tracking, and telemetry functions. The cost and schedule benefits of the project should exceed the other available options of flight in actual manned aircraft or sounding rockets. The vehicle will be remotely piloted with a reliable command and control system independent of the devices under test. It must account for any failure modes, and have contingencies to maximize safety of the operations. The UAV will provide standardized mounting, protection, and power to the devices under test. Considerations of airspace, FAA regulations, and authorizations for UAV operations must be thoroughly evaluated. This rapid demonstration capability will expedite development and initial. testing of advanced range systems projects, and provide gains in overall UAV knowledge, at a reasonable cost. The project fits well within existing ARTWG (Advanced Range Technology Working Group) Roadmaps for the future of Range Systems

    Time-Resolved Intraband Relaxation of Strongly-Confined Electrons and Holes in Colloidal PbSe Nanocrystals

    Full text link
    The relaxation of strongly-confined electrons and holes between 1P and 1S levels in colloidal PbSe nanocrystals has been time-resolved using femtosecond transient absorption spectroscopy. In contrast to II-VI and III-V semiconductor nanocrystals, both electrons and holes are strongly confined in PbSe nanocrystals. Despite the large electron and hole energy level spacings (at least 12 times the optical phonon energy), we consistently observe picosecond time-scale relaxation. Existing theories of carrier relaxation cannot account for these experimental results. Mechanisms that could possibly circumvent the phonon bottleneck in IV-VI quantum dots are discussed

    Hyperglycemia as a risk factor for the development of retinopathy of prematurity

    Get PDF
    BACKGROUND: Hyperglycemia has recently been described as a risk factor for the development of retinopathy of prematurity (ROP), a proliferative vascular disease of the retina that primarily affects premature infants. This study was to evaluate the relationship of hyperglycemia and the development of ROP in premature infants less than 32 weeks gestation. METHODS: This was a retrospective cohort study of all infants less than 32 weeks gestation from 2003–2007 who survived to discharge in our NICU. Demographic data including birthweight, gestational age, Apgar scores, method of delivery, antenatal steroid use, neonatal steroid use, and size for gestational age was collected for each infant. Episodes of sepsis, grade of intraventricular hemorrhage, presence of a patent ductus arteriosus, number of days on the ventilator, and stage of necrotizing enterocolitis were assessed as well as days of hyperglycemia, defined as number of days with whole blood glucose > 150 mg/dl. In addition, the highest stage of ROP was recorded for each infant. A Student’s two tailed t-test or Fisher’s exact test was performed to identify significant clinical risk factors associated with the development of ROP. From this univariate analysis, a multiple logistic regression was performed to determine the effect of hyperglycemia on the development of ROP, adjusting for significant clinical risk factors. Statistical analysis was performed using SAS v.9.2. RESULTS: Univariate analysis demonstrated that infants with ROP were of lower birthweight and gestational age, and were affected by a patent ductus arteriosus, neonatal sepsis, intraventricular hemorrhage, have significant lung disease and received postnatal glucocorticoid therapy. Infants with ROP experienced more days with hyperglycemia (7 vs. 2, p = < 0.0001). Using multiple logistic regression analysis to compare no ROP vs. all stages of ROP, gestational age (OR 0.745, 95% CI [0.634, 0.877], p = 0.0004), mean days of hyperglycemia (OR 1.073, 95% CI [1.004, 1.146], p = 0.04), and mean days receiving mechanical ventilation (OR 1.012, 95% CI [1.000, 1.025], p = 0.05) remained significantly associated with ROP after adjusting for other risk factors. CONCLUSION: Our data suggests that hyperglycemia is associated with the development of ROP in premature infants

    Psychiatric Diagnoses in Individuals with Non-Syndromic Oral Clefts:A Danish Population-Based Cohort Study

    Get PDF
    The aim of this study was to investigate the risk of psychiatric diagnoses in individuals with non-syndromic oral clefts (OC) compared with individuals without OC, including ages from 1 to 76 years.Linking four Danish nationwide registers, we investigated the risk of psychiatric diagnoses at Danish psychiatric hospitals during the period 1969-2012 for individuals born with non-syndromic OC in Denmark 1936-2009 compared with a cohort of 10 individuals without OC per individual with OC, matched by sex and birth year. The sample included 8,568 individuals with OC, observed for 247,821 person-years, and 85,653 individuals without OC followed for 2,501,129 person-years.A total of 953 (11.1%) of the individuals with OC (9.6% for cleft lip (CL), 10.8% for cleft lip and palate (CLP) and 13.1% for cleft palate (CP)) and 8,117 (9.5%) in the comparison group had at least one psychiatric diagnosis. Cox proportional hazard regression model revealed that individuals with OC had significantly higher risk of a psychiatric diagnosis (hazard ratio (HR) = 1.19, 95% CI: 1.12-1.28). When examining cleft type, no difference was found for CL (HR = 1.03, 95% CI: 0.90-1.17), but CLP was associated with a small increased risk (HR = 1.13, 95% CI: 1.01-1.26), whereas individuals with CP had the largest increased risk (HR = 1.45, 95% CI: 1.30-1.62). The largest differences were found in schizophrenia-like disorders, mental retardation and pervasive developmental disorders, but we found no increased risk of mood disorders and anxiety-related disorders.Individuals with non-syndromic OC had significantly higher risk of psychiatric diagnoses compared with individuals without OC. However, the elevated risk was observed for individuals with CLP and CP but not for individuals with CL and the absolute risk increase was modest

    Racial gaps in child health insurance coverage in four south American countries: The role of wealth, human capital, and other household characteristics

    Get PDF
    Objective. To evaluate the extent of racial gaps in child health insurance coverage in South America and study the contribution of wealth, human capital, and other household characteristics to accounting for racial disparities in insurance coverage. Data Sources/Study Setting. Primary data collected between 2005 and 2006 in 30 pediatric practices in Argentina, Brazil, Ecuador, and Chile. Design. Country-specific regression models are used to assess differences in insurance coverage by race. A decomposition model is used to quantify the extent to which wealth, human capital, and other household characteristics account for racial disparities in insurance coverage. Data Collection/Extraction Methods. In-person interviews were conducted with the mothers of 2,365 children. Principal Findings. The majority of children have no insurance coverage except in Chile. Large racial disparities in insurance coverage are observed. Household wealth is the single most important household-level factor accounting for racial disparities in coverage and is significantly and positively associated with coverage, followed by maternal education and employment/occupational status. Geographic differences account for the largest part of racial disparities in insurance coverage in Argentina and Ecuador. Conclusions. Increasing the coverage of children in less affluent families is important for reducing racial gaps in health insurance coverage in the study countries.Fil: Wehby, George. University of Iowa; Estados UnidosFil: Murray, Jeffrey C.. University of Iowa; Estados UnidosFil: McCarthy, Ann Marie. University of Iowa; Estados UnidosFil: Castilla, Eduardo Enrique. Centro de Educación Medica E Invest.clinicas; Argentina. Fundación Oswaldo Cruz; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    The effects of oral clefts on hospital use throughout the lifespan

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Oral clefts are one of the most common birth defects worldwide. They require multiple healthcare interventions and add significant burden on the health and quality of life of affected individuals. However, not much is known about the long term effects of oral clefts on health and healthcare use of affected individuals. In this study, we evaluate the effects of oral clefts on hospital use throughout the lifespan.</p> <p>Methods</p> <p>We estimate two-part regression models for hospital admission and length of stay for several age groups up to 68 years of age. The study employs unique secondary population-based data from several administrative inpatient, civil registration, demographic and labor market databases for 7,670 individuals born with oral clefts between 1936 and 2002 in Denmark, and 220,113 individuals without oral clefts from a 5% random sample of the total birth population from 1936 to 2002.</p> <p>Results</p> <p>Oral clefts significantly increase hospital use for most ages below 60 years by up to 233% for children ages 0-10 years and 16% for middle age adults. The more severe cleft forms (cleft lip with palate) have significantly larger effects on hospitalizations than less severe forms.</p> <p>Conclusions</p> <p>The results suggest that individuals with oral clefts have higher hospitalization risks than the general population throughout most of the lifespan.</p

    Real-time crowd control of existing interfaces

    Get PDF
    Crowdsourcing has been shown to be an effective approach for solving difficult problems, but current crowdsourcing systems suffer two main limitations: (i) tasks must be repackaged for proper display to crowd workers, which generally requires substantial one-off programming effort and support infrastructure, and (ii) crowd workers generally lack a tight feedback loop with their task. In this paper, we introduce Legion, a system that allows end users to easily capture existing GUIs and outsource them for collaborative, real-time control by the crowd. We present mediation strategies for integrating the input of multiple crowd workers in real-time, evaluate these mediation strategies across several applications, and further validate Legion by exploring the space of novel applications that it enables

    Quantile effects of prenatal care utilization on birth weight in Argentina

    Get PDF
    The effects of prenatal care utilization on birth weight (BW) may vary by unobserved fetal health endowments. This heterogeneity will be masked by estimating the effects at BW mean but can be evaluated by estimating the effects at BW quantiles as fetal health endowment is a strong correlate with the BW quantile order. We estimated the effects of prenatal care visits and delay before prenatal care initiation, on BW mean and quantiles using a sample of infants from Argentina. Self-selection into prenatal care was modeled using 2SLS and instrumental variable quantile regression. Results suggest that the 'mean' effect of prenatal care utilization largely underestimates the effects at lower BW quantiles. About 35 and 77 g increase in BW mean and 0.1 quantile respectively, per visit and about 30 and 139 g decrease in BW mean and 0.1 quantile respectively, per week delayed, were estimated. Ignoring self-selection into prenatal care resulted in underestimation of mean and quantile effects. Results highlight the limitation of analyses focused on 'mean effects' in the presence of treatment heterogeneity and emphasize the importance of identifying women at risk for having infants at lower BW quantiles as they may benefit most from earlier and more intensive prenatal care.Instituto Multidisciplinario de Biología Celula
    • …
    corecore