13,349 research outputs found
COBE's Constraints on the Global Monopole and Texture Theories of Cosmic Structure Formation
We report on a calculation of large scale anisotropy in the cosmic microwave
background radiation in the global monopole and texture models for cosmic
structure formation. We have evolved the six component linear gravitational
field along with the monopole or texture scalar fields numerically in an
expanding universe and performed the Sachs-Wolfe integrals directly on the
calculated gravitational fields. On scales , we find a Gaussian
distribution with an approximately scale invariant fluctuation spectrum. The
amplitude is a factor of 4-5 larger than the prediction of the
standard CDM model with the same Hubble constant and density fluctuation
normalization. The recently reported COBE-DMR results imply that global
monopole and texture models require high bias factors or a large Hubble
constant in contrast to standard CDM which requires very low and bias
values. For , we find that normalizing
to the COBE results implies (95\% c.l.). If we restrict
ourselves to the range of bias factors thought to be reasonable before the
announcement of the COBE results, 1.5 \lsim b_8 \lsim 2.5, then it is fair to
conclude that global monopoles and textures are consistent with the COBE
results and are a {\it better} fit than Standard CDM.Comment: 8 pages, 5 figures (not included, but available by mail),
CfPA-TH-92-2
Synthesis of titanium-containing ZSM-48
Titanium-containing ZSM-48 is synthesized with silicon to titanium ratios of 26 or larger; changes in unit cell volume and IR data show that titanium is incorporated into framework positions
Microbial ecology of Thiobacillus ferrooxidans
FINAL TECHNICAL REPORT
TO
U.S. DEPARTMENT OF THE INTERIOR
Geological Survey
Washington. D.C.The contents of this report were developed in part under a grant from
the Department of the Interior, U.S. Geological Survey. Grant number 14-08-0001-61313
Mrgprd Enhances Excitability in Specific Populations of Cutaneous Murine Polymodal Nociceptors
The Mas-related G protein-coupled receptor D (Mrgprd) is selectively expressed in nonpeptidergic nociceptors that innervate the outer layers of mammalian skin. The function of Mrgprd in nociceptive neurons and the physiologically relevant somatosensory stimuli that activate Mrgprd^-expressing (Mrgprd^+) neurons are currently unknown. To address these issues, we studied three Mrgprd knock-in mouse lines using an ex vivo somatosensory preparation to examine the role of the Mrgprd receptor and Mrgprd+ afferents in cutaneous somatosensation. In mouse hairy skin, Mrgprd, as marked by expression of green fluorescent protein reporters, was expressed predominantly in the population of nonpeptidergic, TRPV1-negative, C-polymodal nociceptors. In mice lacking Mrgprd, this population of nociceptors exhibited decreased sensitivity to cold, heat, and mechanical stimuli. Additionally, in vitro patch-clamp studies were performed on cultured dorsal root ganglion neurons from Mrgprd^(–/–) and Mrgprd^(+/–) mice. These studies revealed a higher rheobase in neurons from Mrgprd^(–/–) mice than from Mrgprd^(+/–) mice. Furthermore, the application of the Mrgprd ligand β-alanine significantly reduced the rheobase and increased the firing rate in neurons from Mrgprd^(+/–) mice but was without effect in neurons from Mrgprd^(–/–) mice. Our results demonstrate that Mrgprd influences the excitability of polymodal nonpeptidergic nociceptors to mechanical and thermal stimuli
Aquarius Final Release Product and Full Range Calibration of L-band Radiometers
Aquarius final product V5.0 has been released. The dataset includes close to four years of global radiometric measurements at L-band. The mission's objective was to monitor sea surface salinity, but other applications of its data over land and the cryosphere have been developed. For this reason, it is important to have accurate calibration over the full range of antenna temperatures from natural targets. It is also needed in order to combine Aquarius measurements with other L-band sensors. Aquarius calibration is strongly focused on the ocean. We present a research product which is part of the final release and aims at producing an accurate calibration from the low end (celestial sky) to the high end (land and ice) of the brightness temperature scale. We calibrate the Aquarius radiometers using measurements over the Sky and oceans and assess the new calibration using measurements over land
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