5,672 research outputs found

    Correlation of Preston-tube data with laminar skin friction (Log No. J12984)

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    Preston tube data within laminar boundary layers obtained on a sharp ten-degree cone in the NASA Ames eleven-foot transonic wind tunnel are correlated with the corresponding values of theoretical skin friction. Data were obtained over a Mach number range of 0.30 to 0.95 and unit Reynolds numbers of 9.84, 13.1, and 16.4 million per meter. The rms scatter of skin friction coefficient about the correlation is of the order of one percent, which is comparable to the reported accuracy for calibrations of Preston tubes in incompressible pipe flows. In contrast to previous works on Preston tube/skin friction correlations, which are based on the physical height of the probe's face, this satisfactory correlation for compressible boundary layer flows is achieved by accounting for the effects of a variable "effective" height of the probe. The coefficients, which appear in the correlation, are dependent on the particular tunnel environment. The general procedure can be used to define correlations for other wind tunnels

    Determining Return on Investment for Professional Development In Public Education: A Model

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    Return on investment with respect to employee training is a growing phenomenon in business and industry, as understanding the impact of training on an organization is often not enough. Public educational systems also spend a significant amount of resources on professional development. However, because education is a non-revenue generating industry, rarely do we analyze return on investment in the educational sector. This article examines return on investment for public school teacher training and professional development. While this model was developed for a specific school system and software, the model outlined below may be used by administrators in many non-profit or social organizations to determine a professional development return on investment

    Differential Transcriptome Responses to Aflatoxin B1 in the Cecal Tonsil of Susceptible and Resistant Turkeys

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    The nearly-ubiquitous food and feed-borne mycotoxin aflatoxin B1 (AFB1) is carcinogenic and mutagenic, posing a food safety threat to humans and animals. One of the most susceptible animal species known and thus a good model for characterizing toxicological pathways, is the domesticated turkey (DT), a condition likely due, at least in part, to deficient hepatic AFB1-detoxifying alpha-class glutathione S-transferases (GSTAs). Conversely, wild turkeys (Eastern wild, EW) are relatively resistant to the hepatotoxic, hepatocarcinogenic and immunosuppressive effects of AFB1 owing to functional gene expression and presence of functional hepatic GSTAs. This study was designed to compare the responses in gene expression in the gastrointestinal tract between DT (susceptible phenotype) and EW (resistant phenotype) following dietary AFB1 challenge (320 ppb for 14 days); specifically in cecal tonsil which functions in both nutrient absorption and gut immunity. RNAseq and gene expression analysis revealed significant differential gene expression in AFB1-treated animals compared to control-fed domestic and wild birds and in within-treatment comparisons between bird types. Significantly upregulated expression of the primary hepatic AFB1-activating P450 (CYP1A5) as well as transcriptional changes in tight junction proteins were observed in AFB1-treated birds. Numerous pro-inflammatory cytokines, TGF-β and EGF were significantly down regulated by AFB1 treatment in DT birds and pathway analysis suggested suppression of enteroendocrine cells. Conversely, AFB1 treatment modified significantly fewer unique genes in EW birds; among these were genes involved in lipid synthesis and metabolism and immune response. This is the first investigation of the effects of AFB1 on the turkey gastro-intestinal tract. Results suggest that in addition to the hepatic transcriptome, animal resistance to this mycotoxin occurs in organ systems outside the liver, specifically as a refractory gastrointestinal tract

    Altered Gene Response to Aflatoxin B\u3csub\u3e1\u3c/sub\u3e in the Spleens of Susceptible and Resistant Turkeys

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    Susceptibility and/or resistance to aflatoxin B1 (AFB1) is a threshold trait governed principally by glutathione S transferase (GST)-mediated detoxification. In poultry, domesticated turkeys are highly sensitive to AFB1, most likely due to dysfunction in hepatic GSTs. In contrast, wild turkeys are comparatively resistant to aflatoxicosis due to the presence of functional hepatic GSTAs and other possible physiological and immunological interactions. The underlying genetic basis for the disparate GST function in turkeys is unknown as are the broader molecular interactions that control the systemic response. This study quantifies the effects of dietary AFB1 on gene expression in the turkey spleen, specifically contrasting genetically distinct domesticated (DT, susceptible) and Eastern wild (EW, resistant) birds. Male turkey poults were subjected to a short-term AFB1 treatment protocol with feed supplemented with 320 ppb AFB1 beginning on day 15 of age and continuing for 14 days. Spleen tissues were harvested and subjected to deep RNA sequencing and transcriptome analysis. Analysis of differential gene expression found the effects of AFB1 treatment on the spleen transcriptomes considerably more prominent in the DT birds compared to EW. However, expression of the differentially expressed genes (DEGs) was directionally biased, with the majority showing higher expression in EW (i.e., down-regulation in DT). Significantly altered pathways included FXR/RXR and LXR/RXR activation, coagulation system, prothrombin activation, acute phase response, and atherosclerosis signaling. Differential extra-hepatic expression of acute phase protein genes was confirmed by quantitative real time PCR (qRT-PCR) in the original experiment and additional turkey lines. Results demonstrate that wild turkeys possess a capacity to more effectively respond to AFB1exposure

    Analytic Considerations in Economic Evaluations of Multinational Cardiovascular Clinical Trials

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    OBJECTIVES: The growing number of economic evaluations that use data collected in multinational clinical trials raises numerous questions regarding their execution and interpretation. Although recommendations for conducting economic evaluations have been widely disseminated, relatively little guidance has been given for conducting economic evaluations alongside clinical trials, particularly multinational trials. METHODS: Building on a literature review that was conducted in preparation for an expert workshop, we evaluated a subset of methodological issues related to conducting economic evaluations alongside multinational clinical trials. RESULTS: We found wide variation in the types of costs included as part of the analyses and in the methods used to assign costs to hospitalization events. Furthermore, we found that the extrapolation of costs and survival outcomes beyond the trial period is an inconsistent practice and is often not dependent on whether a survival benefit was observed in the trial or on the epidemiology or practice patterns in the country to which the findings are directed. CONCLUSIONS: Although the limited sample size precluded a quantitative analysis of trial characteristics and their associations with the methodologies employed, our findings highlight the need for more guidance to analysts regarding the execution of economic evaluations using data from multinational clinical trials. As the research community grapples with the complexities of methodological and logistical issues involved in multinational economic evaluations, the development of a standardized format to report the basic methodological characteristics of such studies would help to improve transparency and comparability for other analysts and decision-makers

    A performance comparison of two small rocket nozzles

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    An experimental study was conducted on two small rockets (110 N thrust class) to directly compare a standard conical nozzle with a bell nozzle optimized for maximum thrust using the Rao method. In large rockets, with throat Reynolds numbers of greater than 1 x 10(exp 5), bell nozzles outperform conical nozzles. In rockets with throat Reynolds numbers below 1 x 10(exp 5), however, test results have been ambiguous. An experimental program was conducted to test two small nozzles at two different fuel film cooling percentages and three different chamber pressures. Test results showed that for the throat Reynolds number range from 2 x 10(exp 4) to 4 x 10(exp 4), the bell nozzle outperformed the conical nozzle. Thrust coefficients for the bell nozzle were approximately 4 to 12 percent higher than those obtained with the conical nozzle. As expected, testing showed that lowering the fuel film cooling increased performance for both nozzle types

    Proceedings of the 2008 Center for Homeland Defense and Security Security Annual Conference

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    This article appeared in Homeland Security Affairs (April 2008), Supplement no.2The 2008 Center for Homeland Defense and Security (CHDS) Annual Conference was conducted January 29-30, 2008, at the Naval Postgraduate School in Monterey, California. Its theme, Five Years of Meeting the Homeland Security Challenge, was tied to the fifth anniversary of the establishment of CHDS. More than 230 CHDS master's degree and Executive Leadership Program alumni, partners, sponsors and stakeholders participated in the event. The conference featured a keynote speaker; a question and answer plenary session with a panel of senior Homeland Defense and Security government executives; and three breakout sessions dealing with issues in Intelligence and Information Sharing, Border Security, and Public and Private Integration. These proceedings summarize the presentations and sessions from the conference.Approved for public release; distribution is unlimited

    CREME: The 2011 Revision of the Cosmic Ray Effects on Micro-Electronics Code

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    We describe a tool suite, CREME, which combines existing capabilities of CREME96 and CREME86 with new radiation environment models and new Monte Carlo computational capabilities for single event effects and total ionizing dose

    A Preliminary Investigation towards the Risk Stratification of Allogeneic Stem Cell Recipients with Respect to the Potential for Development of GVHD via Their Pre-Transplant Plasma Lipid and Metabolic Signature

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    The clinical outcome of allogeneic hematopoietic stem cell transplantation (SCT) may be influenced by the metabolic status of the recipient following conditioning, which in turn may enable risk stratification with respect to the development of transplant-associated complications such as graft vs. host disease (GVHD). To better understand the impact of the metabolic profile of transplant recipients on post-transplant alloreactivity, we investigated the metabolic signature of 14 patients undergoing myeloablative conditioning followed by either human leukocyte antigen (HLA)-matched related or unrelated donor SCT, or autologous SCT. Blood samples were taken following conditioning and prior to transplant on day 0 and the plasma was comprehensively characterized with respect to its lipidome and metabolome via liquid chromatography/mass spectrometry (LCMS) and gas chromatography/mass spectrometry (GCMS). A pro-inflammatory metabolic profile was observed in patients who eventually developed GVHD. Five potential pre-transplant biomarkers, 2-aminobutyric acid, 1-monopalmitin, diacylglycerols (DG 38:5, DG 38:6), and fatty acid FA 20:1 demonstrated high sensitivity and specificity towards predicting post-transplant GVHD. The resulting predictive model demonstrated an estimated predictive accuracy of risk stratification of 100%, with area under the curve of the ROC of 0.995. The likelihood ratio of 1-monopalmitin (infinity), DG 38:5 (6.0), and DG 38:6 (6.0) also demonstrated that a patient with a positive test result for these biomarkers following conditioning and prior to transplant will be at risk of developing GVHD. Collectively, the data suggest the possibility that pre-transplant metabolic signature may be used for risk stratification of SCT recipients with respect to development of alloreactivity
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