Planning research in the area of launch vehicle and propulsion programs Progress report, 1-31 Mar. 1968

Program and report reviews on launch vehicle upper stages and propulsion of advanced reentry spacecraf

Domain Dynamics of Magnetic Films with Perpendicular Anisotropy

We study the magnetic properties of nanoscale magnetic films with large perpendicular anisotropy comparing polarization microscopy measurements on Co_28Pt_72 alloy samples based on the magneto-optical Kerr effect with Monte Carlo simulations of a corresponding micromagnetic model. We focus on the understanding of the dynamics especially the temperature and field dependence of the magnetisation reversal process. The experimental and simulational results for hysteresis, the reversal mechanism, domain configurations during the reversal, and the time dependence of the magnetisation are in very good qualitative agreement. The results for the field and temperature dependence of the domain wall velocity suggest that for thin films the hysteresis can be described as a depinning transition of the domain walls rounded by thermal activation for finite temperatures.Comment: 7 pages Latex, Postscript figures included, accepted for publication in Phys.Rev.B, also availible at: http://www.thp.Uni-Duisburg.DE/Publikationen/Publist_Us_R.htm

Prediction of a surface state and a related surface insulator-metal transition for the (100) surface of stochiometric EuO

We calculate the temperature and layer-dependent electronic structure of a 20-layer EuO(100)-film using a combination of first-principles and model calculation based on the ferromagnetic Kondo-lattice model. The results suggest the existence of a EuO(100) surface state which can lead to a surface insulator-metal transition.Comment: 9 pages, 5 figures, Phys. Rev. Lett. (in press

Controlled Waterfowl Hunting At Lake Odessa, Louisa County, Iowa

The Lake Odessa Public Hunting Area supports two systems of regulated waterfowl hunting. Control Area A consists of 55 marked blind sites which are chosen randomly by hunters during a daily drawing. Hunters using the second area, Control Area B, are not restricted to blind sites and a daily fee is not required, but all parties must possess a valid permit. Hunter use of Control Area A was uniform throughout the 1972 and 1973 hunting seasons due to the better mallard (Anas platy rhynchos) shooting on that area. Control Area B hunter use decreased as the season progressed, reflecting the early migration of wood ducks (Aix sponsa) which were more prevalent. In 1973, a year of poor mallard production but good wood duck production, hunter use of Control Area B increased over the previous year as hunters sought wood ducks. Hunters using Control Area A belonged to higher income, education, and occupation brackets, spent more money on equipment, and drove further to hunt than hunters in Control Area B. Hunter success was positively related to increasing values of vegetation parameters, but the dominant influence was not apparent. A heavy zone of annual emergent vegetation appeared to influence hunter success, but a lack of this zone could be compensated for with a strong representation of buttonbush (Cephalanthus occidentalis). Sites on medium-sized water areas (14-20 ac.) with a strong zone of annual emergent vegetation produced the highest success rates in 1972, but the same or similar sites produced low success rates in 1973 after severe loss of vegetation. Because of reduced annual emergent vegetation on the area and the receding zones of bottonbush, a summer drawdown of water level was recommended

A comparison of the fermentation patterns of six commercial wine yeasts

The fermentation properties of six commercial yeast strains, Prise de Mousse (PM), Pasteur Champagne (PC), Swiss (S), Montrachet (M), Epernay 2 (E) and Chanson (C) were compared in grape juices and Yeast Nitrogen Base (YNB). None of the strains fermented a 23 ° Brix Chardonnay juice to complete dryness. S resulted in the smallest amount of residual sugar followed by E. PM, PC and S all fermented 19.7 and 22.0 °Brix Gewürztraminer juices to dryness. PM produced the greatest amounts of alcohol in Chardonnay juicP. fortified to 30 ° Brix followed in order by PC, S, and M, E and C. C consistently produced the least amount of alcohol. There was no significant difference in alcohol production by the first five strains at 20 ° Brix and no significant difference among the first four strains at 25 ° Brix. PM produced the highest concentrations of ethanol in YNB containing 11.1 or 12.9 % (v/v) ethanol at the time of inoculation. PC and C produced significantly less alcohol. Temperature has a profound effect on the ability of the yeast strains to grow and ferment sugar in YNB. With the exception of PM at 20 °C, none of the strains fermented the 22 % glucose completely in YNB by the end of 25 d. The higher temperature 30 °C was particularly detrimental to yeast growth and fermentation. Generally, the most complete fermentations occurred at 20 °C. PM was most tolerant of decanoic and octanoic acids

Beyond the random phase approximation in the Singwi-Sj\"olander theory of the half-filled Landau level

We study the $\nu=1/2$ Chern-Simons system and consider a self-consistent field theory of the Singwi-Sj\"olander type which goes beyond the random phase approximation (RPA). By considering the Heisenberg equation of motion for the longitudinal momentum operator, we are able to show that the zero-frequency density-density response function vanishes linearly in long wavelength limit independent of any approximation. From this analysis, we derive a consistency condition for a decoupling of the equal time density-density and density-momentum correlation functions. By using the Heisenberg equation of motion of the Wigner distribution function with a decoupling of the correlation functions which respects this consistency condition, we calculate the response functions of the $\nu=1/2$ system. In our scheme, we get a density-density response function which vanishes linearly in the Coulomb case for zero-frequency in the long wavelength limit. Furthermore, we derive the compressibility, and the Landau energy as well as the Coulomb energy. These energies are in better agreement to numerical and exact results, respectively, than the energies calculated in the RPA.Comment: 9 Revtex pages, 4 eps figures, typos correcte