1,247 research outputs found
Data catalog series for space science and applications flight missions. Volume 4A: Descriptions of meteorological and terrestrial applications spacecraft and investigations
The National Space Science Data Center (NSSDC) provides data from and information about space science and applications flight investigations in support of additional studies beyond those performed as the principal part of any flight mission. The Earth-orbiting spacecraft for investigations of the earth and its atmosphere is discussed. Geodetic tracking data are included in this category. The principal subject areas presented are meteorology and earth resources survey, and the spacecraft selection is made according to those subjects. All experiments on board the spacecraft are described. No attempt is made to reference investigations that are related to the above disciplines, but that are described in other volumes of this series
The PARSE Programming Paradigm. Part I: Software Development Methodology. Part II: Software Development Support Tools
The programming methodology of PARSE (parallel software environment), a software environment being developed for reconfigurable non-shared memory parallel computers, is described. This environment will consist of an integrated collection of language interfaces, automatic and semi-automatic debugging and analysis tools, and operating system βall of which are made more flexible by the use of a knowledge-based implementation for the tools that make up PARSE. The programming paradigm supports the user freely choosing among three basic approaches /abstractions for programming a parallel machine: logic-based descriptive, sequential-control procedural, and parallel-control procedural programming. All of these result in efficient parallel execution. The current work discusses the methodology underlying PARSE, whereas the companion paper, βThe PARSE Programming Paradigm β II: Software Development Support Tools,β details each of the component tools
Stochastic Ballistic Annihilation and Coalescence
We study a class of stochastic ballistic annihilation and coalescence models
with a binary velocity distribution in one dimension. We obtain an exact
solution for the density which reveals a universal phase diagram for the
asymptotic density decay. By universal we mean that all models in the class are
described by a single phase diagram spanned by two reduced parameters. The
phase diagram reveals four regimes, two of which contain the previously studied
cases of ballistic annihilation. The two new phases are a direct consequence of
the stochasticity. The solution is obtained through a matrix product approach
and builds on properties of a q-deformed harmonic oscillator algebra.Comment: 4 pages RevTeX, 3 figures; revised version with some corrections,
additional discussion and in RevTeX forma
Controlling Curie temperature in (Ga,Ms)As through location of the Fermi level within the impurity band
The ferromagnetic semiconductor (Ga,Mn)As has emerged as the most studied
material for prototype applications in semiconductor spintronics. Because
ferromagnetism in (Ga,Mn)As is hole-mediated, the nature of the hole states has
direct and crucial bearing on its Curie temperature TC. It is vigorously
debated, however, whether holes in (Ga,Mn)As reside in the valence band or in
an impurity band. In this paper we combine results of channeling experiments,
which measure the concentrations both of Mn ions and of holes relevant to the
ferromagnetic order, with magnetization, transport, and magneto-optical data to
address this issue. Taken together, these measurements provide strong evidence
that it is the location of the Fermi level within the impurity band that
determines TC through determining the degree of hole localization. This finding
differs drastically from the often accepted view that TC is controlled by
valence band holes, thus opening new avenues for achieving higher values of TC.Comment: 5 figures, supplementary material include
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