The space shuttle launch vehicle aerodynamic verification challenges

The Space Shuttle aerodynamics and performance communities were challenged to verify the Space Shuttle vehicle (SSV) aerodynamics and system performance by flight measurements. Historically, launch vehicle flight test programs which faced these same challenges were unmanned instrumented flights of simple aerodynamically shaped vehicles. However, the manned SSV flight test program made these challenges more complex because of the unique aerodynamic configuration powered by the first man-rated solid rocket boosters (SRB). The analyses of flight data did not verify the aerodynamics or performance preflight predictions of the first flight of the Space Transportation System (STS-1). However, these analyses have defined the SSV aerodynamics and verified system performance. The aerodynamics community also was challenged to understand the discrepancy between the wind tunnel and flight defined aerodynamics. The preflight analysis challenges, the aerodynamic extraction challenges, and the postflight analyses challenges which led to the SSV system performance verification and which will lead to the verification of the operational ascent aerodynamics data base are presented

Theory of Adsorption and Surfactant Effect of Sb on Ag (111)

We present first-principles studies of the adsorption of Sb and Ag on clean and Sb-covered Ag (111). For Sb, the {\it substitutional} adsorption site is found to be greatly favored with respect to on-surface fcc sites and to subsurface sites, so that a segregating surface alloy layer is formed. Adsorbed silver adatoms are more strongly bound on clean Ag(111) than on Sb-covered Ag. We propose that the experimentally reported surfactant effect of Sb is due to Sb adsorbates reducing the Ag adatom mobility. This gives rise to a high density of Ag islands which coalesce into regular layers.Comment: RevTeX 3.0, 11 pages, 0 figures] 13 July 199

Differentiating between the effect of rapid dietary acculturation and the effect of living away from home for the first time, on the diets of Greek students studying in Glasgow

The diets of University students, particularly those living away from the family home, are characterised by a number of undesirable practices such as meal skipping, frequent snacking and low intakes of fruits and vegetables. This study aimed to identify the extent to which the previously reported negative changes in the eating habits of Greek students living in Glasgow were the result of rapid dietary acculturation (the 'Glasgow effect'), and the extent to which these changes were the result of living away from the family home for the first time. Using a self-administered questionnaire, we assessed the diets before and after commencing University of Greek Students living in the family home (n = 43) or away from home either in Greece (n = 37) or in Glasgow (n = 55). No significant changes were observed in the diets Of Students who continued to live at home after starting university. Significant changes observed only in the Students living in Glasgow were decreases in consumption frequency of fresh fruits, meat and cheese, and increases in consumption of snack foods. These changes were attributed to rapid dietary acculturation. Young Greek adults faced difficulties in maintaining a traditional Mediterranean diet after leaving the family home, particularly after moving to a Northern European environment