Rational approximations to Tricomi's psi function Interim report, 20 Mar. - 19 Jun. 1968

Closed form rational approximations to Tricomi psi functio

Thermal stress analysis of space shuttle orbiter subjected to reentry aerodynamic heating

A structural performance and resizing (SPAR) finite-element computer program and NASA structural analysis (NASTRAN) finite-element computer programs were used in the thermal stress analysis of the space shuttle orbiter subjected to reentry aerodynamic heating. A SPAR structural model was set up for the entire left wing of the orbiter, and NASTRAN structural models were set up for: (1) a wing segment located at midspan of the orbiter left wing, and (2) a fuselage segment located at midfuselage. The thermal stress distributions in the orbiter structure were obtained and the critical high thermal stress regions were identified. It was found that the thermal stresses induced in the orbiter structure during reentry were relatively low. The thermal stress predictions from the whole wing model were considered to be more accurate than those from the wing segment model because the former accounts for temperature and stress effects throughout the entire wing

Deaths Exceed Births in Most of Europe, But Not in the United States

In this brief, authors Kenneth Johnson, Layton Fields, and Dudley Poston, Jr. present important new findings about the diminishing number of births compared to deaths in Europe and the United States from their recent article in Population and Development Review. Their research focuses on the prevalence and dynamics of natural decrease in subareas of Europe and the United States in the first decade of the twenty-first century using counties (United States) or county-equivalents (Europe). The authors report that 58 percent of the 1,391 counties of Europe had more deaths than births during that period compared to just 28 percent of the 3,137 U.S. counties. Natural decrease is more widespread in Europe because its population is older, fertility rates are lower, and there are fewer women of child-bearing age. Natural decrease is a major policy concern because it drains the demographic resilience from a region, diminishing its economic viability and competitiveness. The implications of the recent European immigrant surge for natural decrease are uncertain, but the authors’ analysis suggests that natural decrease is likely to remain widespread in Europe for the foreseeable future

Buckling behavior of Rene 41 tubular panels for a hypersonic aircraft wing

The buckling characteristics of Rene 41 tubular panels for a hypersonic aircraft wing were investigated. The panels were repeatedly tested for buckling characteristics using a hypersonic wing test structure and a universal tension/compression testing machine. The nondestructive buckling tests were carried out under different combined load conditions and in different temperature environments. The force/stiffness technique was used to determine the buckling loads of the panel. In spite of some data scattering, resulting from large extrapolations of the data fitting curve (because of the termination of applied loads at relatively low percentages of the buckling loads), the overall test data correlate fairly well with theoretically predicted buckling interaction curves. Also, the structural efficiency of the tubular panels was found to be slightly higher than that of beaded panels

Got Caries? Breast milk and Early Childhood Caries?

Objective: To provide an analysis of the association between the longevity of breastfeeding and development of ECC. Determine the optimal time frame in which mothers should cease breastfeeding to reduce ECC development. Methods: Dr. Brickhouse, PubMed, Google Scholar and other scholarly databases were utilized to find current scientific evidence on the effects of breast milk on ECC. Relevant articles were summarized to write a review of literature. 16 articles published from 2015 to the present date were reviewed and cited. Results: From the studies, there is strong evidence to support breastfeeding beyond 12 months of age increases the prevalence of ECC. Furthermore, increased frequency and duration of breastfeeding leads to higher incidence of ECC. Conclusion: Findings indicate dental health care providers should recommend either ceasing breastfeeding at 12 months of age or provide ECC prevention education to caregivers. Further research is required to minimize data discrepancies between US and international countries.https://scholarscompass.vcu.edu/denh_student/1002/thumbnail.jp

Development of an integrated, zero-G pneumatic transporter/rotating-paddle incinerator/catalytic afterburner subsystem for processing human waste on board spacecraft

A baseline laboratory prototype of an integrated, six man, zero-g subsystem for processing human wastes onboard spacecraft was investigated, and included the development of an operational specification for the baseline subsystem, followed by design and fabrication. The program was concluded by performing a series of six tests over a period of two weeks to evaluate the performance of the subsystem. The results of the tests were satisfactory, however, several changes in the design of the subsystem are required before completely satisfactory performance can be achieved