Sonic Boom Computations for a Mach 1.6 Cruise Low Boom Configuration and Comparisons with Wind Tunnel Data

Accurate analysis of sonic boom pressure signatures using computational fluid dynamics techniques remains quite challenging. Although CFD shows accurate predictions of flow around complex configurations, generating grids that can resolve the sonic boom signature far away from the body is a challenge. The test case chosen for this study corresponds to an experimental wind-tunnel test that was conducted to measure the sonic boom pressure signature of a low boom configuration designed by Gulfstream Aerospace Corporation. Two widely used NASA codes, USM3D and AERO, are examined for their ability to accurately capture sonic boom signature. Numerical simulations are conducted for a free-stream Mach number of 1.6, angle of attack of 0.3 and Reynolds number of 3.85x10(exp 6) based on model reference length. Flow around the low boom configuration in free air and inside the Langley Unitary plan wind tunnel are computed. Results from the numerical simulations are compared with wind tunnel data. The effects of viscous and turbulence modeling along with tunnel walls on the computed sonic boom signature are presented and discussed

Probiotics in pregnancy: inequities in knowledge exchange, attitudes, and use of probiotics in a socio-demographically diverse, cross-sectional survey sample of pregnant Canadians

Background: pregnancy interventions, potentially including consumption of nutraceuticals like probiotics, represent possible avenues for preventing non-communicable diseases. However, evidence syntheses indicate that probiotic interventions, while effective in managing some pregnancy complications (e.g., gestational diabetes), do not confer health benefits to uncomplicated pregnancies. Messaging around probiotics in pregnancy is mixed, such that people with low-risk pregnancies may nevertheless feel pressure to spend limited resources on (costly) probiotics. To tailor knowledge exchange and support safe, equitable access to pregnancy probiotics when their prescription may be warranted, we need to understand who takes probiotics during pregnancy and under what conditions. Methods: we used chi-square and logistic regression analyses of anonymous, cross-sectional survey data from 341 pregnant Canadians of diverse socio-demographic backgrounds to assess which respondents, by socio-demographic characteristics and pre-pregnancy/pregnancy health indicators, were relatively likely to: perceive probiotics as beneficial to pregnancy health and/or report taking probiotics during pregnancy. Results: forty-seven percent of respondents perceived probiotics as beneficial to pregnancy health; 51 % reported consuming them. Probiotic attitudes and consumption were socio-demographically-patterned: higher-income, post-secondary-educated respondents disproportionately perceived probiotics as healthy and consumed them. There was no evidence of variation in probiotics attitudes or use by pregnancy health indicators. Conclusion: Socio-economic factors may be more important determinants of pregnancy probiotic use in this sample than indications for pregnancy complications. Clear guidelines on pregnancy probiotics that reflect current evidence are needed. Equitable access to probiotics should be facilitated for pregnant people likely to benefit from interventions (i.e., those with certain complications), supporting long-term health equity.</p