943 research outputs found

    AVGS, AR and D for Satellites, ISS, the Moon, Mars and Beyond

    Get PDF
    With the continuous need to rotate crew and re-supply the International Space Station (ISS) and the desire to return humans to the Moon and for the first time, place humans on Mars, NASA must develop a more robust and highly reliable capability to perform Autonomous Rendezvous and Capture (AR&C) because, unlike the Apollo missions, NASA plans to send the entire crew to the Lunar or Martian surface and must be able to dock with the Orion spacecraft upon return. In 1997, NASA developed the Video Guidance Sensor (VGS) which was flown and tested on STS-87 and STS-95. In 2001, NASA designed and built a more enhanced version of the VGS, called the Advanced Video Guidance Sensor (AVGS). The AVGS offered significant technology improvements to the precursor VGS design. This paper will describe the AVGS as it was in the DART mission of 2005 and the Orbital Express mission of 2007. The paper will describe the capabilities and design concepts of the AVGS as it was flown on the DART 2005 Mission and the DARPA Orbital Express Mission slated to fly in 2007. The paper will cover the Flight Software, problems encountered, testing for Orbital Express and where NASA is going in the future

    Genetically determined height and coronary artery disease.

    Get PDF
    BACKGROUND: The nature and underlying mechanisms of an inverse association between adult height and the risk of coronary artery disease (CAD) are unclear. METHODS: We used a genetic approach to investigate the association between height and CAD, using 180 height-associated genetic variants. We tested the association between a change in genetically determined height of 1 SD (6.5 cm) with the risk of CAD in 65,066 cases and 128,383 controls. Using individual-level genotype data from 18,249 persons, we also examined the risk of CAD associated with the presence of various numbers of height-associated alleles. To identify putative mechanisms, we analyzed whether genetically determined height was associated with known cardiovascular risk factors and performed a pathway analysis of the height-associated genes. RESULTS: We observed a relative increase of 13.5% (95% confidence interval [CI], 5.4 to 22.1; P<0.001) in the risk of CAD per 1-SD decrease in genetically determined height. There was a graded relationship between the presence of an increased number of height-raising variants and a reduced risk of CAD (odds ratio for height quartile 4 versus quartile 1, 0.74; 95% CI, 0.68 to 0.84; P<0.001). Of the 12 risk factors that we studied, we observed significant associations only with levels of low-density lipoprotein cholesterol and triglycerides (accounting for approximately 30% of the association). We identified several overlapping pathways involving genes associated with both development and atherosclerosis. CONCLUSIONS: There is a primary association between a genetically determined shorter height and an increased risk of CAD, a link that is partly explained by the association between shorter height and an adverse lipid profile. Shared biologic processes that determine achieved height and the development of atherosclerosis may explain some of the association. (Funded by the British Heart Foundation and others.)

    Prediction of glycosylation sites using random forests

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Post translational modifications (PTMs) occur in the vast majority of proteins and are essential for function. Prediction of the sequence location of PTMs enhances the functional characterisation of proteins. Glycosylation is one type of PTM, and is implicated in protein folding, transport and function.</p> <p>Results</p> <p>We use the random forest algorithm and pairwise patterns to predict glycosylation sites. We identify pairwise patterns surrounding glycosylation sites and use an odds ratio to weight their propensity of association with modified residues. Our prediction program, GPP (glycosylation prediction program), predicts glycosylation sites with an accuracy of 90.8% for Ser sites, 92.0% for Thr sites and 92.8% for Asn sites. This is significantly better than current glycosylation predictors. We use the trepan algorithm to extract a set of comprehensible rules from GPP, which provide biological insight into all three major glycosylation types.</p> <p>Conclusion</p> <p>We have created an accurate predictor of glycosylation sites and used this to extract comprehensible rules about the glycosylation process. GPP is available online at <url>http://comp.chem.nottingham.ac.uk/glyco/</url>.</p

    Serum amyloid A primes microglia for ATP-dependent interleukin-1\u3b2 release

    Get PDF
    Acute-phase response is a systemic reaction to environmental/inflammatory insults and involves production of acute-phase proteins, including serum amyloid A (SAA). Interleukin-1\u3b2 (IL-1\u3b2), a master regulator of neuroinflammation produced by activated inflammatory cells of the myeloid lineage, in particular microglia, plays a key role in the pathogenesis of acute and chronic diseases of the peripheral nervous system and CNS. IL-1\u3b2 release is promoted by ATP acting at the purinergic P2X7 receptor (P2X7R) in cells primed with toll-like receptor (TLR) ligands

    Evaluation of E-Learning Lessons for Strengthening Early Childhood Practitioner Use of Family Capacity-Building Practices

    Get PDF
    Findings from a case study field-test evaluation of e-learning lessons for promoting early childhood intervention practitioners’ understanding and use of family capacity-building practices are described. Participants were two early childhood program directors, two early childhood technical assistance providers, and two early childhood intervention practitioners. Pattern matching was used to evaluate whether or not participants with different roles and responsibilities judged the instructional design, interactivity, video illustrations, and usefulness of the e-learning lessons similarly or differently. Results indicated that the different features of the e-learning lessons were rated highly by all but one participant and that the patterns of responses were much the same regardless of participants’ professional roles or responsibilities. Participant feedback and suggestions were used to revise the e-learning lessons and correct technical problems

    Behavioral interventions to decrease disparity among African American women with hypertension

    Get PDF
    The purpose of the project is to use a community-based approach to deliver evidence-based behavioral intervention strategies framed by the Theory of Planned Behavior to help increase awareness of hypertension among African American women

    "Give me some space" : exploring youth to parent aggression and violence

    Get PDF
    A small scale qualitative project, undertaken by an interdisciplinary domestic violence research group involving academic researchers and research assistants, with colleagues from Independent Domestic Abuse Services (IDAS), investigated youth aggression and violence against parents. Following the literature review, data was generated through several research conversations with young people (n = 2), through semi-structured interviews with mothers (n = 3) and practitioners (n = 5), and through a practitioner focus group (n = 8). Thematic analysis and triangulation of the data from parents, practitioners and young people, elicited interconnected and complex overarching themes. Young people could be both victim and perpetrator. The witnessing or experiencing of domestic aggression and violence raised the concept of ‘bystander children’. The impact of young people experiencing familial violence was underestimated by parents. For practitioners, the effects of working with domestic violence was shown to be significant - both positively and negatively

    Variations in Environmental Tritium Dose Estimates Due to Meteorological Data Averaging and Uncertainties in Pathway Model Parameters

    Full text link
    The large amounts of tritium produced at the Savannah River Site (SRS) coupled with the current dose reconstruction study at the facility emphasize the importance of ensuring accurate and efficient prediction of tritium doses to the public. Presently, dose estimates to the general population in the site vicinity are calculated annually using a five year meteorological database. Determining whether detailed monthly dose estimates are necessary or whether annual averaged data is sufficient offers the potential for more efficient dose prediction. In this study, off site collective committed doses and maximum individual doses due to atmospheric tritium releases were calculated according to the methods outlined in the U.S. Nuclear Regulatory Commission's Regulatory Guide 1.109 and compared using monthly versus five-year meteorological data and source terms. Site-specific variables not currently utilized at SRS for annual dose estimates also have been included. In addition, the range of predicted doses, based on the distribution in model parameters given in the literature, were estimated. Finally, a sensitivity analysis was performed in order to determine the influence of model inputs on dose estimates. Results corroborate previous studies by indicating that the primary contributor to infant tritium dose is the ingestion of milk, while for all other age groups, the most important pathway is the ingestion of vegetation. These relative pathway contributions remain constant throughout the year for infants; for children, teenagers, and adults, however, inhalation and absorption of tritium through the skin increases in relative importance in the months of June to September. It was found that the model utilized was most sensitive to dose factors, the ratio of the specific activity of tritium oxide in vegetation to the specific activity of atmospheric tritium oxide, and breathing rates. Most importantly, it was found that over a five-year period, the use of averaged meteorological data results in total individual doses that are only 2 to 6% higher than doses determined monthly, depending on the pathway of interest.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42693/1/10661_2004_Article_141219.pd

    Reproduced from the journal Health Physics with permission from the Health Physics Society

    Get PDF
    ABSTRACT The models used in the NRC approach to assess chronic atmospheric releases of radioactivity generate deterministic dose estimates by using standard assumptions about exposure conditions and environmental transport mechanisms. This approach has been used at the Savannah River Site since 1983. Total dose to off-site maximum individuals at the SRS from atmospheric releases has been on the order of 1 µSv/yr, three orders of magnitude lower than the applicable dose limit. When estimating atmospheric dose many parameters remain unchanged each time calculations are performed. These parameters, therefore, are essentially unimportant with regard to routine modeling. It is proposed, therefore, that transport and dosimetry models can be reduced to simple functions of a few parameters that essentially determine dose at all locations across the site. The three-parameter transport and dosimetry model developed in this work is useful for quick and easy estimates of chronic atmospheric tritium dose that are within a factor of 2 of estimates by more sophisticated models. The three parameters critical to estimating annual average concentration at the Savannah River Site are wind-direction frequency, downwind distance, and physical stack height. The model is bounded by physical stack heights between 10 and 61 meters and downwind distances between 800 m (0.5 mi.) and 32 km (20 mi.) and should not be used outside its intended domain. It requires knowledge of wind-direction frequency, downwind distance, and physical stack height to estimate an Atmospheric Dose Factor (ADF; in units of µSv/GBq) for the conversion of long-term release activity to maximum individual effective dose equivalent. This concept is being carried forward to the development of a reduced model for particulate emissions from SRS stacks.
    corecore