Use of a hyperbolic grid generation scheme in simulating supersonic viscous flow about three-dimensional winged configuration

The present paper describes a numerical mesh generation technique to be used with an implicit finite difference method for simulating visous supersonic flow about low-aspect-ratio wing body configurations using a single grid strategy. The computational domain is segmented into multiple regions, with borders located in supersonic areas to avoid the otherwise costly interfacing procedure between adjacent segments. The numerical procedure is applied to calculate the turbulent flow around the shuttle orbiter and a canard projectile at supersonic free stream Mach number

Viscous computation of a space shuttle flow field

A procedure is presented, as well as some results, to calculate the flow over the winged orbiter. This necessitates the use of two computer codes. A parabolized marching Navier-Stokes code is used to obtain the solution up to the bow shock-wing shock interaction region and for the region after the interaction. An unsteady Navier-Stokes code is to be used in the region of the shock interaction. Only resuls for the marching code are presented. For the flow conditions calculated, M infinity = 7.9, alpha = 25 deg, T(wall) = 540 R, Re(L) = 60728 per inch, laminar or turbulent, the PNS code was marched up to an X/L = 0.7 which is where the bow shock-wing shock interaction region occurs

Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

Recent multi-photon ionization (MPI) experiments on uracil revealed a fragment ion at m/z 84 that was proposed as a potential marker for ring opening in the electronically excited neutral molecule. The present MPI measurements on deuterated uracil identify the fragment as C3H4N2O+ (uracil+ less CO), a plausible dissociative ionization product from the theoretically predicted open-ring isomer. Equivalent measurements on thymine do not reveal an analogous CO loss channel, suggesting greater stability of the excited DNA base. MPI and electron impact ionization experiments have been carried out on uracil-adenine clusters in order to better understand the radiation response of uracil within RNA. Evidence for C3H4N2O+ production from multi-photon-ionized uracil-adenine clusters is tentatively attributed to a significant population of π-stacked configurations in the neutral beam

Sunlight exposure is just one of the factors which influence Vitamin D status

© The Royal Society of Chemistry and Owner Societies. Studies on the determinants of vitamin D status have tended to concentrate on input-exposure to ultraviolet B radiation and the limited sources in food. Yet, vitamin D status, determined by circulating concentrations of 25-hydroxyvitamin D (25(OH)D), can vary quite markedly in groups of people with apparently similar inputs of vitamin D. There are small effects of polymorphisms in the genes for key proteins involved in vitamin D production and metabolism, including 7-dehydrocholesterol reductase, which converts 7-dehydrocholesterol, the precursor of vitamin D, to cholesterol, CYP2R1, the main 25-hydroxylase of vitamin D, GC, coding for the vitamin D binding protein which transports 25(OH)D and other metabolites in blood and CYP24A1, which 24-hydroxylates both 25(OH)D and the hormone, 1,25-dihydroxyvitamin D. 25(OH)D has a highly variable half-life in blood. There is evidence that the half-life of 25(OH)D is affected by calcium intake and some therapeutic agents. Fat tissue seems to serve as a sink for the parent vitamin D, which is released mainly when there are reductions in adiposity. Some evidence is presented to support the proposal that skeletal muscle provides a substantial site of sequestration of 25(OH)D, protecting this metabolite from degradation by the liver, which may help to explain why exercise, not just outdoors, is usually associated with better vitamin D status

Role assigning and taking in cloud computing

The widespread use of cloud computing (CC) has brought to the forefront information technology (IT) governance issues, rendering the lack of expertise in handling CC-based IT controls a major challenge for business enterprises and other societal organizations. In the cloud-computing context, this study identifies and ranks the determinants of role assigning and taking by IT people. The study’s integrative research links CC and IT governance to humane arrangements, as it validates and ranks role assigning and taking components through in-depth interviews with twelve IT decision-makers and forty-four Information Systems Audit and Control Association (ISACA) members, engaged as panelists in a Delphi technique implementation. The empirical results recognize skills and competencies as prioritized determinants of IT controls, while IT security, risk and compliance emerge as capabilities crucial to evaluate and manage CC service providers. Despite the study’s generalizability limitations, its findings highlight future research paths and provide practical guidelines toward the high technology of open-market IT self-governance. The latter entails the humane flows of collegial control and responsibility, as opposed to the inhumane flows of authority and power, under the sequestered technique of the bureaucratically-hierarchized IT hetero-governanc

Variations in certain biological aspects of the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae) in relation to color of its forms

The stock populations of two groups of Aphis gossypii Glover (Homoptera: Aphididae) were collected from cucurbitaceous plant leaves cultivated in Assiut and the New Valley Governorates, Egypt. Both aphid groups were brought into the laboratory and used as base line of pirimicarb resistance. Pirimicarb LC50 base line was determined by the dipping technique in successive concentrations of the trade form of pirimicarb mixed in water. The LC25 was determined monthly throughout two years and used in the selection.. This procedure resulted four aphid forms at each location (i.e., base line, mixed, light color, and dark color).  It was found that the total nymphal duration of dark forms collected from both locations did not vary significantly from the base line forms. Data of the reproductive biology of aphids from both locations showed that the fecundity period, longevity and productivity of the dark morphs were significantly higher than those of the base line ones

Prevalence and Predictors of Insulin Resistance in Non-Obese Healthy Young Females in Qatar

The state of Qatar suffers from diabetes epidemic due to obesity-associated metabolic syndrome. However, the prevalence of insulin resistance prior to obesity, which could play an important role in the high prevalence of diabetes, has not yet been described. This study aims to compare the prevalence of insulin resistance in apparently healthy non-obese and obese participants from Qatar and identify the predictors of insulin resistance in different body massindex(BMI)-groups. In this cross-sectional study, 150 young healthy females from Qatar were dichotomized into four groups (underweight, normal weight, overweight and obese) based on their BMI. Anthropometric measures as well as fasting plasma levels of lipids, adipokines, blood glucose and insulin were recorded. The prevalence of insulin resistance as per homeostatic model assessment of insulin resistance (HOMA-IR) was estimated and differences between insulin sensitive and insulin resistant were compared. Linear models were used to identify predictors of insulin resistance in every BMI group. Prevalence of insulin resistance in non-obese healthy females from Qatar ranges between 7% and 37%and increases with BMI. Overall, predictors of insulin resistance in the Qatari population are triglycerides/high-density lipoprotein (HDL) ratio and free fat mass but vary according to the BMI group. The main predictors were triglycerides in normal weight, triglycerides/HDL in overweight and triglycerides/HDL and interleukin-6 (IL-6) in obese individuals. The high prevalence of insulin resistance in non-obese Qataris may partially explain diabetes epidemic. Larger studies are warranted to confirm these findings and identify underlying causes for insulin resistance in non-obese individuals in Qatar, aiming at targeted intervention before diabetes onsetThis project was funded by Qatar University (grant number QUST-CAS-FALL-14\15-35). The publication of this article was funded by the Qatar National Library

Development of two reference materials for all trans-retinol, retinyl palmitate, α- and γ-tocopherol in milk powder and infant formula

AbstractVitamins are important food constituents that can be present in almost every foodstuff. Food quality and safety depends on food surveillance by reliable quantitative analysis enabled by appropriate quality control. Certified matrix reference materials are versatile tools to support quality assurance and control. However, in the case of vitamins, which are important in various foods, there is a lack of matrix reference materials. Two certified reference materials for the determination of all–trans-retinol, retinyl palmitate, and α- and γ-tocopherol in milk powder and infant formula have been developed by the National Institute of Standards, Egypt. This article presents the preparation, characterization, homogeneity, and stability testing as well as statistical treatment of data and certified value assignment. The assignment of the certified values and associated uncertainties in the prepared natural-matrix reference materials were based on the widely used approach of combining data from independent and reliable analytical methods