1,917 research outputs found
Real-time determination of laser beam quality by modal decomposition
We present a real-time method to determine the beam propagation ratio M2 of
laser beams. The all-optical measurement of modal amplitudes yields M2
parameters conform to the ISO standard method. The experimental technique is
simple and fast, which allows to investigate laser beams under conditions
inaccessible to other methods.Comment: 8 pages, 4 figures, published in Optics Expres
Coupled Facility-Payload Vibration Modeling Improvements
A major phase of aerospace hardware verification is vibration testing. The standard approach for such testing is to use a shaker to induce loads into the payload. In preparation for vibration testing at National Aeronautics and Space Administration/Goddard Space Flight Center an analysis is performed to assess the responses of the payload. A new method of modeling the test is presented that takes into account dynamic interactions between the facility and the payload. This dynamic interaction has affected testing in the past, but been ignored or adjusted for during testing. By modeling the combined dynamics of the facility and test article (payload) it is possible to improve the prediction of hardware responses. Many aerospace test facilities work in similar way to those at NASA/Goddard Space Flight Center. Lessons learned here should be applicable to other test facilities with similar setups
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Racial/ethnic heterogeneity in associations of blood pressure and incident cardiovascular disease by functional status in a prospective cohort: the Multi-Ethnic Study of Atherosclerosis.
OBJECTIVES:Research has demonstrated that the association between high blood pressure and outcomes is attenuated among older adults with functional limitations, compared with healthier elders. However, it is not known whether these patterns vary by racial/ethnic group. We evaluated race/ethnicity-specific patterns of effect modification in the association between blood pressure and incident cardiovascular disease (CVD) by functional status. SETTING:We used data from the Multi-Ethnic Study of Atherosclerosis (2002-2004, with an average of 8.8 years of follow-up for incident CVD). We assessed effect modification of systolic blood pressure and cardiovascular outcomes by self-reported physical limitations and by age. PARTICIPANTS:The study included 6117 participants (aged 46 to 87; 40% white, 27% black, 22% Hispanic and 12% Chinese) who did not have CVD at the second study examination (when self-reported physical limitations were assessed). OUTCOME MEASURES:Incident CVD was defined as an incident myocardial infarction, coronary revascularisation, resuscitated cardiac arrest, angina, stroke (fatal or non-fatal) or death from CVD. RESULTS:We observed weaker associations between systolic blood pressure (SBP) and CVD among white adults with physical limitations (incident rate ratio (IRR) per 10 mm Hg higher SBP: 1.09 (95% CI 0.99 to 1.20)) than those without physical limitations (IRR 1.29 (1.19, 1.40); P value for interaction <0.01). We found a similar pattern among black adults. Poor precision among the estimates for Hispanic or Chinese participants limited the findings in these groups. The attenuated associations were consistent across both multiplicative and additive scales, though physical limitations showed clearer patterns than age on an additive scale. CONCLUSION:Attenuated associations between high blood pressure and incident CVD were observed for blacks and whites with poor function, though small sample sizes remain a limitation for identifying differences among Hispanic or Chinese participants. Identifying the characteristics that distinguish those in whom higher SBP is associated with less risk of morbidity or mortality may inform our understanding of the consequences of hypertension among older adults
Transcriptome Analysis in Spleen Reveals Differential Regulation of Response to Newcastle Disease Virus in Two Chicken Lines.
Enhancing genetic resistance of chickens to Newcastle Disease Virus (NDV) provides a promising way to improve poultry health, and to alleviate poverty and food insecurity in developing countries. In this study, two inbred chicken lines with different responses to NDV, Fayoumi and Leghorn, were challenged with LaSota NDV strain at 21 days of age. Through transcriptome analysis, gene expression in spleen at 2 and 6 days post-inoculation was compared between NDV-infected and control groups, as well as between chicken lines. At a false discovery rate <0.05, Fayoumi chickens, which are relatively more resistant to NDV, showed fewer differentially expressed genes (DEGs) than Leghorn chickens. Several interferon-stimulated genes were identified as important DEGs regulating immune response to NDV in chicken. Pathways predicted by IPA analysis, such as "EIF-signaling", "actin cytoskeleton organization nitric oxide production" and "coagulation system" may contribute to resistance to NDV in Fayoumi chickens. The identified DEGs and predicted pathways may contribute to differential responses to NDV between the two chicken lines and provide potential targets for breeding chickens that are more resistant to NDV
Much Ado About Nothing? On the Categorial Status of et and ne in Medieval French
In this article, we reconsider the syntactical analysis as well as the categorial status of two Medieval French elements, et and ne. In this connection, we illustrate and compare various approaches which principally differ with regard to the assignment of a unique category or of various categories to these elements. In the context of this comparison, we address some of the questions pertaining to their motivations and the evidence which has been offered in their favor, showing that approaches which assign a unique category to et and ne, respectively, prove to be empirically more adequate.Beaucoup de bruit pour rien ? A propos du statut catégoriel de et ainsi que de ne en français médiéval Dans cet article nous proposons une réflexion sur l’analyse syntaxique et le statut de deux éléments du français médiéval : et et ne. A cette fin, nous envisageons et illustrons différentes approches qui se distinguent principalement en ce qui concerne l’attribution d’un statut catégoriel unique ou multiple à ces éléments. En comparant ces approches, nous abordons les questions qui président à leurs motivations et nous débattons les arguments proposés en leur faveur, à la lumière des faits observés. Il s’ensuit que l’approche qui attribue un statut catégoriel cohérent à chacun des deux éléments en question s’avère la plus pertinente
Much Ado About Nothing? On the Categorial Status of et and ne in Medieval French
In this article, we reconsider the syntactical analysis as well as the categorial status of two Medieval French elements, et and ne. In this connection, we illustrate and compare various approaches which principally differ with regard to the assignment of a unique category or of various categories to these elements. In the context of this comparison, we address some of the questions pertaining to their motivations and the evidence which has been offered in their favor, showing that approaches which assign a unique category to et and ne, respectively, prove to be empirically more adequate.Beaucoup de bruit pour rien ? A propos du statut catégoriel de et ainsi que de ne en français médiéval Dans cet article nous proposons une réflexion sur l’analyse syntaxique et le statut de deux éléments du français médiéval : et et ne. A cette fin, nous envisageons et illustrons différentes approches qui se distinguent principalement en ce qui concerne l’attribution d’un statut catégoriel unique ou multiple à ces éléments. En comparant ces approches, nous abordons les questions qui président à leurs motivations et nous débattons les arguments proposés en leur faveur, à la lumière des faits observés. Il s’ensuit que l’approche qui attribue un statut catégoriel cohérent à chacun des deux éléments en question s’avère la plus pertinente
Determination of the Baryon Density from Large Scale Galaxy Redshift Surveys
We estimate the degree to which the baryon density, , can be
determined from the galaxy power spectrum measured from large scale galaxy
redshift surveys, and in particular, the Sloan Digital Sky Survey. A high
baryon density will cause wiggles to appear in the power spectrum, which should
be observable at the current epoch. We assume linear theory on scales and do not include the effects of redshift distortions, evolution,
or biasing. With an optimum estimate of to ,
the uncertainties in are roughly 0.07 and 0.016 in flat
and open () cosmological models, respectively. This result
suggests that it should be possible to test for consistency with big bang
nucleosynthesis estimates of if we live in an open universe.Comment: 23 Pages, 10 Postscript figure
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