3,153 research outputs found

    Combustion Model of Supersonic Rocket Exhausts in an Entrained Flow Enclosure

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    This paper describes the Computation Fluid Dynamics (CFD) model developed to simulate the supersonic rocket exhaust in an entrained flow cylinder. The model can be used to study the plume-induced environment due to static firing test of the Taurus II launch vehicle. The finite rate chemistry is used to model the combustion process involving rocket propellant (RP 1) and liquid oxidizer (LOX). A similar chemical reacting model is also used to simulate the mixing of rocket plume and ambient air. The model provides detailed information on the gas concentration and other flow parameters within the enclosed region thus allowing different operating scenarios to be examined in an efficient manner. It is shown that the real gas influence is significant and yields better agreement with the theory

    KSC VAB Aeroacoustic Hazard Assessment

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    NASA Kennedy Space Center (KSC) carried out an analysis of the effects of aeroacoustics produced by stationary solid rocket motors in processing areas at KSC. In the current paper, attention is directed toward the acoustic effects of a motor burning within the Vehicle Assembly Building (VAB). The analysis was carried out with support from ASRC Aerospace who modeled transmission effects into surrounding facilities. Calculations were done using semi-analytical models for both aeroacoustics and transmission. From the results it was concluded that acoustic hazards in proximity to the source of ignition and plume can be severe; acoustic hazards in the far-field are significantly lower

    Large Scale Production of Spider Silk Protein in E. coli

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    Spider silks have long been a focus of research due to their remarkable mechanical properties including strength, toughness and elasticity. Moreover, biodegradability and biocompatibility of spider silks make them beneficial to use in biomedical applications. Spiders cannot be farmed because of their territorial and cannibalistic nature. Hence, production of recombinant spider silks is the only feasible solution for large scale production Large scale production is still challenging due to the small recombinant protein size, low yield and low water solubility of bio-synthetic spider silk. The current study reports our progress as well as evolution of effective protocol for large scale bio-synthetic production of spider silk protein in E. coli. Our main spidersilk protein we seek to produce and purify in a large scale is MaSp2. Spider dragline silk is primarily composed of proteins called major ampullate spidroins (MaSps) that consist of a large repeat array flanked by nonrepetitive N- and C- terminal domains. All MaSp genes are co-expressed in the major ampullate gland of Nephila Clavipes

    Efeitos dos esportes de combate sobre a massa óssea: revisão sistemática

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    To determine the influence of combat sports on bone mass. Methods: A systematic review was performed according to the PRISMA method, with searches in the Pubmed, Bireme, Embase and Web of Science databases covering the period 1900 to 2015, using the keywords "martial arts", "fight", "combat","karate","kung fu","tae kwon do","judo","aikido","bone mass","bone health","bone tissue","bone density", and "bone mineral contents The articles were searched for and retrieved electronically and manually, by two independent reviewers. Results: Seventy-nine articles were identified, of which 25 were duplicates, leaving 54 for reading and evaluation of the titles; next, articles about diseases such as bone and/or orthopedic injuries, maxillofacial, surgeries, fractures, osteoporosis and osteopenia in women, prevention of falls, and physical fitness were excluded, leaving 15 articles. Of the articles selected and retrieved in full, all were published between 2002 and 2015. One article was a case control study; two were longitudinal studies, two were randomized studies; and 10 were cross-sectional studies. A total of 1368 children, adolescents, adults and elderly subjects were involved in combat sports and had bone evaluation by imaging. Factors such as calorie intake, calcium and/or vitamin D, intensity and volume of the exercise, hormonal aspects as bone markers, and characteristics of menopause are not conclusive in relation to bone mass, and further studies are needed. Conclusion:The practice of combat sports shows a significant improvement in bone mass at all ages253240244COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESVerificar a influência dos esportes de combate sobre a massa óssea. Foi realizada revisão sistemática da literatura de acordo com o método PRISMA, com buscas nas bases de dados Pubmed, Bireme, Embase e Web of Science, referente ao período de 1900 a 2015, com os descritores “martial arts”, “fight”, “combat”, “karate”, “kung fu”, “tae kwon do”, “judo”, “aikido”, “bone”, “bone mass”, “bone health”, “bone tissue”, “bone density”, “bone mineral contents”. A busca e a recuperação dos artigos foram realizadas por meio eletrônico e manual, executadas por dois revisores independentes. Foram identificados 79 artigos, dos quais, 25 eram duplicados, restando 54 artigos para leitura e avaliação dos títulos; posteriormente, foram excluídos os que tratavam de doenças como lesões ortopédicas e/ou ósseas, maxilofaciais, cirurgias, fraturas, mulheres osteopênicas e osteoporóticas, prevenção de quedas e aptidão física, restando 15 artigos. Dos estudos selecionados e encontrados na íntegra, todos foram publicados entre 2002 e 2015. Apenas um era estudo de caso controle, dois eram estudos longitudinais, dois estudos randomizados e 10 estudos transversais. Verificou-se um total de 1.368 crianças, adolescentes, adultos e idosos envolvidos em esportes de combate e avaliação óssea por imagem. Fatores como ingestão calórica, de cálcio e/ou vitamina D, intensidade e volume do exercício, aspectos hormonais como marcadores ósseos e características da menopausa não são conclusivos com relação à massa óssea e requerem um número maior de estudos. A prática de esportes de combate evidencia melhora significativa na massa óssea em todas as idadesLaboratorio de Crescimento e Desenvolvimento do CIPED, Biblioteca - FCM - UNICAMP; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brazil (CAPES)CAPES [001

    Clinical correlates of plasma insulin levels over the life course and association with incident type 2 diabetes: the Framingham Heart Study

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    Introduction Insulin is a glucose-lowering hormone that affects carbohydrate, lipid, and protein metabolism. Limited data exist on the correlates of insulin levels over the life course in healthy community-dwelling individuals. Research design and methods Using multilevel modeling of multiple serial observations over 21 years, we assessed the longitudinal correlates of fasting insulin and the cross-sectional correlates of fasting and 2-hour (2h, post 75 g glucose challenge) plasma insulin concentrations in 2140 relatively healthy Framingham Heart Study participants without diabetes (61% women; mean age, 42 years). We used multivariable-adjusted Cox regression to relate glycemic markers (fasting and 2h-insulin, fasting glucose, 2h-glucose, and hemoglobin A1C) to the risk of type 2 diabetes during follow-up. Results Over the life course, fasting insulin concentrations were inversely associated with age, male sex, and physical activity, whereas waist circumference, the total/high-density lipoprotein (HDL) cholesterol ratio, and blood triglycerides were positively associated with insulin levels (p<0.005 for all). Male sex (inversely related) and the total/HDL cholesterol ratio (positively related) emerged as the most important cross-sectional correlates of 2h-insulin (p<0.005 for all). All markers were associated with higher risk of type 2 diabetes (352 cases, median follow-up 18 years, p<0.001 for all). Conclusions We observed common and distinct correlates of fasting and 2h-insulin levels. Our findings highlight a potential role of insulin in lipid and lipoprotein metabolism. Furthermore, fasting and 2h-insulin are critical markers of future diabetes risk. Further studies are needed to confirm our findings

    A model of diffuse Galactic Radio Emission from 10 MHz to 100 GHz

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    Understanding diffuse Galactic radio emission is interesting both in its own right and for minimizing foreground contamination of cosmological measurements. Cosmic Microwave Background experiments have focused on frequencies > 10 GHz, whereas 21 cm tomography of the high redshift universe will mainly focus on < 0.2 GHz, for which less is currently known about Galactic emission. Motivated by this, we present a global sky model derived from all publicly available total power large-area radio surveys, digitized with optical character recognition when necessary and compiled into a uniform format, as well as the new Villa Elisa data extending the 1.4 GHz map to the entire sky. We quantify statistical and systematic uncertainties in these surveys by comparing them with various global multi-frequency model fits. We find that a principal component based model with only three components can fit the 11 most accurate data sets (at 10, 22, 45 & 408 MHz and 1.4, 2.3, 23, 33, 41, 61, 94 GHz) to an accuracy around 1%-10% depending on frequency and sky region. Both our data compilation and our software returning a predicted all-sky map at any frequency from 10 MHz to 100 GHz are publicly available at http://space.mit.edu/home/angelica/gsm .Comment: Accuracy improved with 5-year WMAP data. Our data, software and new foreground-cleaned WMAP map are available at https://ascl.net/1011.01

    Interventions to improve district-level routine health data in low-income and middle-income countries: a systematic review

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    Background Routine health information system(s) (RHIS) facilitate the collection of health data at all levels of the health system allowing estimates of disease prevalence, treatment and preventive intervention coverage, and risk factors to guide disease control strategies. This core health system pillar remains underdeveloped in many low-income and middle-income countries. Efforts to improve RHIS data coverage, quality and timeliness were launched over 10 years ago. Methods A systematic review was performed across 12 databases and literature search engines for both peer-reviewed articles and grey literature reports on RHIS interventions. Studies were analysed in three stages: (1) categorisation of RHIS intervention components and processes; (2) comparison of intervention component effectiveness and (3) whether the post-intervention outcome improved above the WHO integrated disease surveillance response framework data quality standard of 80% or above. Results 5294 references were screened, resulting in 56 studies. Three key performance determinants - technical, organisational and behavioural - were proposed as critical to RHIS strengthening. Seventy-seven per cent [77%] of studies identified addressed all three determinants. The most frequently implemented intervention components were € providing training' and € using an electronic health management information systems'. Ninety-three per cent [93%] of pre-post or controlled trial studies showed improvements in one or more data quality outputs, but after applying a standard threshold of >80% post-intervention, this number reduced to 68%. There was an observed benefit of multi-component interventions that either conducted data quality training or that addressed improvement across multiple processes and determinants of RHIS. Conclusion Holistic data quality interventions that address multiple determinants should be continuously practised for strengthening RHIS. Studies with clearly defined and pragmatic outcomes are required for future RHIS improvement interventions. These should be accompanied by qualitative studies and cost analyses to understand which investments are needed to sustain high-quality RHIS in low-income and middle-income countries

    Os registros de representação semiótica no estudo da reta com enfoque na geometria analítica

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    Apresenta-se, neste trabalho, o cenário virtual implementado no sistema Sistema Integrado de Ensino e Aprendizagem (SIENA) e os resultados referentes aos conceitos de Reta, que é um recorte da investigação com o conteúdo de Geometria Analítica fundamentado na teoria de Duval sobre os Registros de Representação Semiótica. A pesquisa visou investigar as dificuldades de alunos de Licenciatura em Matemática na conversão dos Registros de representação semiótica, em Geometria Analítica, nos conteúdos de Reta, e as contribuições do sistema SIENA para a identificação dessas dificuldades e na recuperação individualizada deste conteúdo. Adotou-se a metodologia qualitativa, com ênfase no método de estudo de caso. A experiência abrangeu dez alunos do curso de Licenciatura em Matemática, da Universidade Luterana do Brasil/Canoas-RS. Constatou-se que os alunos possuem dificuldades nas conversões entre os registros língua natural, algébrico e gráfico no conteúdo de Reta, devendo-se valorizar mais esta abordagem no processo de ensino e aprendizagem

    Effective Field Theory for Dilute Fermions with Pairing

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    Effective field theory (EFT) methods for a uniform system of fermions with short-range, natural interactions are extended to include pairing correlations, as part of a program to develop a systematic Kohn-Sham density functional theory (DFT) for medium and heavy nuclei. An effective action formalism for local composite operators leads to a free-energy functional that includes pairing by applying an inversion method order by order in the EFT expansion. A consistent renormalization scheme is demonstrated for the uniform system through next-to-leading order, which includes induced-interaction corrections to pairing.Comment: 31 pages, 10 figures, affiliation updated, paper unchange
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