51,698 research outputs found
Debris Disk Radiative Transfer Simulation Tool (DDS)
A WWW interface for the simulation of spectral energy distributions of
optically thin dust configurations with an embedded radiative source is
presented. The density distribution, radiative source, and dust parameters can
be selected either from an internal database or defined by the user. This tool
is optimized for studying circumstellar debris disks where large grains are
expected to determine the far-infrared through millimeter dust reemission
spectral energy distribution. The tool is available at
http://aida28.mpia-hd.mpg.de/~swolf/ddsComment: Comp. Phys. Comm, 2005, in pres
Atrazine Degradation, Sorption and Bioconcentration in Water Systems
The herbicide atrazine is used extensively to control broadleaf and grass weeds in such crops as sorghum and corn. A small portion of the atrazine may be lost from the area of application by surface runoff and could enter a stream or lake. The objective of this study was to evaluate atrazine degradation, sorption, and bioconcentration in watersediment systems. The results indicated that sediments with lower pH values and higher organic matter levels adsorbed higher levels of atrazine than sediments with neutral pH values and lower organic matter levels. Microbial decomposition of the herbicide was slow under the conditions of this study. Accumulation of atrazine by microorganisms in an aqueous system was demonstrated4 The results indicated that the organic fraction of a water system may be the most important adsorption ccmponent. Data from this study will be useful in assessing the ramifications of herbicides in aquatic ecosystems and provide a better understanding of the reactions of herbicides in sediment-water systans
Island Distance in One-Dimensional Epitaxial Growth
The typical island distance in submonlayer epitaxial growth depends on
the growth conditions via an exponent . This exponent is known to
depend on the substrate dimensionality, the dimension of the islands, and the
size of the critical nucleus for island formation. In this paper we study
the dependence of on in one--dimensional epitaxial growth. We
derive that for and confirm this result
by computer simulations.Comment: 5 pages, 3 figures, uses revtex, psfig, 'Note added in proof'
appende
Comment on "Test of constancy of speed of light with rotating cryogenic optical resonators"
A recent experiment by Antonini et. al. [Phys. Rev. A {\bf 71}, 050101R
2005], set new limits on Lorentz violating parameters in the frame-work of the
photon sector of the Standard Model Extension (SME),
, and the Robertson-Mansouri-Sexl (RMS) framework,
. The experiment had significant systematic effects caused by
the rotation of the apparatus which were only partly analysed and taken into
account. We show that this is insufficient to put a bound on
and the bound on represents a
five-fold improvement not a ten-fold improvement as claimed.
(For reply see Phys. Rev. A 72, 066102 (2005) DOI:
10.1103/PhysRevA.72.066102)Comment: 2 page
Experimental assembly of structures in EVA: Hardware morphology and development issues
A large body of data was obtained by MIT during neutral boyancy testing at Marshall Space Flight Center from 1980 to the present. These efforts, and the most significant results are summarized. The Experimental Assembly of Structure in EVA (EASE) flight experiment was undertaken to validate these results and flown on the STS 61-B in November 1985. The EASE experiment hardware is discussed and how the experiment goals dictate its size, shape, and operational characteristics, are illustrated
A theoretical study of the propagation and attenuation of acoustic waves in the lunar surface Interim report
Acoustic wave propagation and attenuation in lunar space environmen
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