21,852 research outputs found
Restoring degraded woodlands
In many places on the Swan Coastal Plain Eucalyptus gomphocephala (tuart) woodlands are in decline or are degraded (Bulletin 1). This occurs for many reasons, including grazing by stock, weed invasion, logging and clearing. It is often a combination of these factors that gradually lead to a decline in the tuart populations
Resonant satellite geodesy study Final report
Resonant satellite orbits for determining geopotential constant
Manual for the Fish Population Surveys (DOC9 Package) for the District Fisheries Analysis System (FAS)
Update of Aquatic Biology Technical Report 87/11; final report of project F-69-R (1-3),
Data Base Management and Analysis of Fisheries in ImpoundmentsReport issued on: issued October 1990INHS Technical Report prepared for Illinois Department of Conservatio
The Fisheries Analysis System (FAS): Creel Survey and Lake Analyses
F-69-R(1-3)Report issued on: October 1990Final report of Project F-69-R(1-3), Data Base Management and Analysis of Fisheries in
Impoundments, conducted under of memorandum of understanding between Illinois Department
of Conservation and the University of Illinois, supported through Fed(TRUNCATED
Subtleties in the quasi-classical calculation of Hawking radiation
he quasi-classical method of deriving Hawking radiation is investigated. In
order to recover the original Hawking temperature one must take into account a
previously ignored contribution coming from the temporal part of the action.
This contribution plus a contribution coming from the spatial part of the
action gives the correct temperature.Comment: 6 pages revtex. Honorable Mention in 2008 GRF essay contest, typos
fixed, sign errors corrected. To be published in Special Issue of IJMP
Microwave ISM Emission Observed by WMAP
We investigate the nature of the diffuse Galactic emission in the Wilkinson
Microwave Anisotropy Probe (WMAP) temperature anisotropy data. Substantial
dust-correlated emission is observed at all WMAP frequencies, far exceeding the
expected thermal dust emission in the lowest frequency channels (23, 33, 41
GHz). The WMAP team (Bennett et al.) interpret this emission as dust-correlated
synchrotron radiation, attributing the correlation to the natural association
of relativistic electrons produced by SNae with massive star formation in dusty
clouds, and deriving an upper limit of 5% on the contribution of Draine &
Lazarian spinning dust at K-band (23 GHz). We pursue an alternative
interpretation that much, perhaps most, of the dust-correlated emission at
these frequencies is indeed spinning dust, and explore the spectral dependence
on environment by considering a few specific objects as well as the full sky
average. Models similar to Draine & Lazarian spinning dust provide a good fit
to the full-sky data. The full-sky fit also requires a significant component
with free-free spectrum uncorrelated with \Halpha, possibly hot (~million K)
gas within 30 degrees of the Galactic center.Comment: ApJ in press (accepted 5 Dec 2003), version 2: corrected typos and
added references. 23 pages, 5 figures, 2 tables. Free-free haze map is
available at http://skymaps.inf
Three-body interactions in complex fluids: virial coefficients from simulation finite-size effects
A simulation technique is described for quantifying the contribution of
three-body interactions to the thermodynamical properties of coarse-grained
representations of complex fluids. The method is based on comparing the third
virial coefficient for a complex fluid with that of an approximate
coarse-grained model described by a pair potential. To obtain we
introduce a new technique which expresses its value in terms of the measured
volume-dependent asymptote of a certain structural function. The strategy is
applicable to both Molecular Dynamics and Monte Carlo simulation. Its utility
is illustrated via measurements of three-body effects in models of star polymer
and highly size-asymmetrical colloid-polymer mixtures.Comment: 13 pages, 8 figure
Hydrogen contamination in Ge-doped SiO[sub 2] thin films prepared by helicon activated reactive evaporation
Germanium-doped silicon oxidethin films were deposited at low temperature by using an improved helicon plasma assisted reactive evaporation technique. The origins of hydrogen contamination in the film were investigated, and were found to be H incorporation during deposition and postdeposition water absorption. The H incorporation during deposition was avoided by using an effective method to eliminate the residual hydrogen present in the depositionsystem. The microstructure, chemical bonds, chemical etch rate, and optical index of the films were studied as a function of the deposition conditions. Granular microstructures were observed in low-density films, and were found to be the cause of postdeposition water absorption. The granular microstructure was eliminated and the film was densified by increasing the helicon plasma power and substrate bias during deposition. A high-density film was shown to have no postdeposition water absorption and no OH detected by using a Fourier-transform infrared spectrometer
An Improved Semi-Analytical Spherical Collapse Model for Non-linear Density Evolution
We derive a semi-analytical extension of the spherical collapse model of
structure formation that takes account of the effects of deviations from
spherical symmetry and shell crossing which are important in the non-linear
regime. Our model is designed so that it predicts a relation between the
peculiar velocity and density contrast that agrees with the results of N-body
simulations in the region where such a comparison can sensibly be made. Prior
to turnaround, when the unmodified spherical collapse model is expect to be a
good approximation, the predictions of the two models coincide almost exactly.
The effects of a late time dominating dark energy component are also taken into
account. The improved spherical collapse model is a useful tool when one
requires a good approximation not just to the evolution of the density contrast
but also its trajectory. Moreover, the analytical fitting formulae presented is
simple enough to be used anywhere where the standard spherical collapse might
be used but with the advantage that it includes a realistic model of the
effects of virialisation.Comment: 6 pages, 3 figures. Matches the version in print at Astrophys.
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