Chebychev Trajectory Optimization Program /CHEBYTOP/ Final report

Digital computer program for interplanetary trajectory optimization and variable thrust dat

Ground state and constrained domain walls in Gd/Fe multilayers

The magnetic ground state of antiferromagnetically coupled Gd/Fe multilayers and the evolution of in-plane domain walls is modelled with micromagnetics. The twisted state is characterised by a rapid decrease of the interface angle with increasing magnetic field. We found that for certain ratios M(Fe):M(Gd), the twisted state is already present at low fields. However, the magnetic ground state is not only determined by the ratio M(Fe):M(Gd) but also by the thicknesses of the layers, that is the total moments of the layer. The dependence of the magnetic ground state is explained by the amount of overlap of the domain walls at the interface. Thicker layers suppress the Fe aligned and the Gd aligned state in favour of the twisted state. Whereas ultrathin layers exclude the twisted state, since wider domain walls can not form in these ultrathin layers

Allometric growth in the Diademodontinae (Reptilia; Therapsida); a preliminary report

Main articleThe hypothesis that many, if not all, of the South African and Zambian specimens, which have been regarded as different diademodontine genera and species, actually consitute a taxonomically homogeneous, ontogenetic growth series is tested. The principles of allometric growth were applied to this sample of fossils, which varied considerably in size and shape. The approach which was followed was exclusively morphometric. The results indicate that these specimens do represent various ontogenetic stages of a growth series of only a single species of Diademodon Seeley.Non

Multilocus Genetic Investigation of Species Limits in the Caddo Mountain Salamander (Plethodon caddoensis)

Alexandra D. Hahn is an undergraduate student in the School of Biological Sciences at Louisiana Tech University. Donald B. Shepard is an Assistant Professor in the School of Biological Sciences at Louisiana Tech University

Preliminary Solar Sail Design and Fabrication Assessment: Spinning Sail Blade, Square Sail Sheet

Blade design aspects most affecting producibility and means of measurement and control of length, scallop, fullness and straightness requirements and tolerances were extensively considered. Alternate designs of the panel seams and edge reinforcing members are believed to offer advantages of seam integrity, producibility, reliability, cost and weight. Approaches to and requirements for highly specialized metalizing methods, processes and equipment were studied and identified. Alternate methods of sail blade fabrication and related special machinery, tooling, fixtures and trade offs were examined. A preferred and recommended approach is also described. Quality control plans, inspection procedures, flow charts and special test equipment associated with the preferred manufacturing method were analyzed and are discussed

Coping with multiple enemies : pairwise interactions do not predict evolutionary change in complex multitrophic communities

Predicting the ecological and evolutionary trajectories of populations in multispecies communities is one of the fundamental challenges in ecology. Many of these predictions are made by scaling patterns observed from pairwise interactions. Here, we show that the coupling of ecological and evolutionary outcomes is likely to be weaker in increasingly complex communities due to greater chance of life-history trait correlations. Using model microbial communities comprising a focal bacterial species (Bacillus subtilis), a bacterial competitor, protist predator and phage parasite, we found that increasing the number of enemies in a community had an overall negative effect on B. subtilis population growth. However, only the competitor imposed direct selection for B. subtilis trait evolution in pairwise cultures and this effect was weakened in the presence of other antagonists that had a negative effect on the competitor. In contrast, adaptation to parasites was driven indirectly by correlated selection where competitors had a positive and predators a negative effect. For all measured traits, selection in pairwise communities was a poor predictor of B. subtilis evolution in more complex communities. Together, our results suggest that coupling of ecological and evolutionary outcomes is interaction-specific and weakly coupled in more complex communities. We conclude that understanding 2 the ecological and evolutionary mechanisms underpinning trait correlations is crucial to predict species response to global change in complex microbial communitie