Multi-calculation rate simulations

It is common in real time simulations of large aerospace systems to separate the high and low frequency subsystems within the simulation and perform the integrations of the subsystems at different calculation rates. This is done to strike a balance between accuracy of calculation and capacity of the digital computer. Questions arising as to the accuracy of this structure compared to single calculation rates were studied using a linear aircraft model. Also investigated were interactions arising to cause errors worse than those expected. Problems are specifically identified and guidelines are given for selection of sample rates for multiple rate simulations

Detection of nanoparticles by means of reflection electron energy loss spectroscopy depth profiling

The various studies of nanoparticles are of great importance because of the wide application of nanotechnology. The shape and structure of the nanoparticles can be determined by transmission electron microscopy (TEM) and their chemistry by electron energy loss spectroscopy. TEM sample preparation is an expensive and difficult procedure, however. Surface sensitive, analytical techniques, such as Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) are well applicable to detect the atoms that make up the nanoparticles, but cannot determine whether particle formation occurred. On the other hand, reflection electron energy loss spectroscopy (REELS) probes the electronic structures of atoms, which are strongly different for the atoms being in solution or in precipitated form. If the particle size is in the nm range, plasmon resonance can be excited in it, which appears as a loss feature in REELS spectrum. Thus, by measuring AES (XPS) spectra parallel with those of REELS, besides the atomic concentrations the presence of the nanoparticles can also be identified. As an example, the appearance of nanoparticles during ion beam induced mixing of C/Si layer will be shown

Ameiva corax

Number of Pages: 2Integrative BiologyGeological Science

Level crossing in the three-body problem for strongly interacting fermions in a harmonic trap

We present a solution of the three-fermion problem in a harmonic potential across a Feshbach resonance. We compare the spectrum with that of the two-body problem and show that it is energetically unfavorable for the three fermions to occupy one lattice site rather than two. We also demonstrate the existence of an energy level crossing in the ground state with a symmetry change of its wave function, suggesting the possibility of a phase transition for the corresponding many-body case.Comment: 5 pages, 6 figures, typos corrected, references adde

ABIDETH FOREVER? GLOBAL USE OF SEMIARID LANDS IN THE INTERWAR YEARS

I have undertaken a highly selective Cook\u27s Tour in this article, attempting to integrate our understanding of semiarid lands around the globe. The focus is concentrated on the period between the two great wars when new nationalisms, old imperial networks, and the burgeoning ambitions of scientists combined to create new systems of land use in the semiarid regions, but a few sorties have been made into earlier and later periods to assist the interpretation of specific projects. My own country, Australia, is used as the starting point for the tour, but the influence of American Donald Worster\u27s Dust Bowl (1979) will be easily discerned. I have argued that the environmental and economic crises around the world in the interwar years were to some extent culturally induced and that they were linked by similar assumptions, crossing cultural and economic lines, about the potential and rationale for settlement in semiarid lands. Heavy investment in science and technology, multiple ways to manage risk and indebtedness, and expansions of the scale of Westernstyle capitalistic farming in semiarid areas were typical of capitalist economies, but consideration is also given to developments in semiarid regions characterized by communist and mixed economies

Flesh on the Bones: Animal Bodies in Atlantic Roundhouses

This volume presents the state of research across Europe to illustrate how comparable interpretative frameworks are used by archaeologists working with both prehistoric and historical societies