46,437 research outputs found
Failure Rate Computations Based on Mariner Mars 1964 Spacecraft Data
Mariner Mars 1964 failure rates computed for use in reliability predictions and cost allocation
Can Effects of Dark Matter be Explained by the Turbulent Flow of Spacetime?
For the past forty years the search for dark matter has been one of the
primary foci of astrophysics, although there has yet to be any direct evidence
for its existence (Porter et al. 2011). Indirect evidence for the existence of
dark matter is largely rooted in the rotational speeds of stars within their
host galaxies, where, instead of having a ~ r^1/2 radial dependence, stars
appear to have orbital speeds independent of their distance from the galactic
center, which led to proposed existence of dark matter (Porter et al. 2011;
Peebles 1993). We propose an alternate explanation for the observed stellar
motions within galaxies, combining the standard treatment of a fluid-like
spacetime with the possibility of a "bulk flow" of mass through the Universe.
The differential "flow" of spacetime could generate vorticies capable of
providing the "perceived" rotational speeds in excess of those predicted by
Newtonian mechanics. Although a more detailed analysis of our theory is
forthcoming, we find a crude "order of magnitude" calculation can explain this
phenomena. We also find that this can be used to explain the graviational
lensing observed around globular clusters like "Bullet Cluster".Comment: 5 pages, Accepted for publication in Journal of Modern Physics:
Gravitation and Cosmology (Sept. 2012
The use of isotopic carbon in a study of the metabolism of anthanilic acid in Neurospora
The finding by Tatum, Banner, and Beadle (l), that the tryptophanless Neurospora mutant strain 10575 accumulates anthranilic acid, which in turn can be utilized for growth of strain 40008, has provided evidence that anthranilic acid is a biochemical precursor of tryptophan in this organism. It has been further established that indole is an intermediate in this conversion (2-5).
More recent work with a number of mutants of Neurospora (6-8) has established that tryptophan is a biochemical precursor to niacin with kynurenine and hydroxyanthranilic acid as intermediates. The accumulated evidence has indicated the existence in the mold of the following series of reactions:
→ Anthranilic acid → indole → tryptophan → kynurenine → 3-hydroxyanthranilic acid → nicotinic acid
In the light of this evidence the present work was undertaken to trace the carbon in the carboxyl group of anthranilic acid in order to estimate its contribution as a structural unit in the formation of niacin and tryptophan. The organism chosen for this investigation was a biochemical mutant strain of Neurospora designated as strain 40008. This mutant utilizes anthranilic acid, indole, or tryptophan for growth.
The mutant was grown in the presence of anthranilic acid containing Cl4 in the carboxyl group. Niacin and tryptophan were isolated from the mold mycelium and tested for radioactivity
Specsim: The MIRI Medium Resolution Spectrometer Simulator
MIRI, the Mid-InfraRed Instrument, is one of four instruments being built for
the James Webb Space Telescope, and is developed jointly between an
EuropeanConsortium and the US. In this paper we present a software data
simulator for one of MIRI's four instruments: the Integral Field Unit (IFU)
Medium Resolution Spectrometer (MIRI-MRS), the first mid-infrared IFU
spectrograph, and one of the first IFUs to be used in a space mission. To give
the MIRI community a preview of the properties of the MIRI-MRS data products
before the telescope is operational, the Specsim tool has been developed to
model, in software, the operation of the spectrometer. Specsim generates
synthetic data frames approximating those which will be taken by the instrument
in orbit. The program models astronomical sources and generates detector frames
using the predicted and measured optical properties of the telescope and MIRI.
These frames can then be used to illustrate and inform a range of operational
activities, including data calibration strategies and the development and
testing of the data reduction software for the MIRI-MRS. Specsim will serve as
a means of communication between the many consortium members by providing a way
to easily illustrate the performance of the spectrometer under different
circumstances, tolerances of components and design scenarios.Comment: 8 pages, 5 figures; A high resolution version is available at
http://www.roe.ac.uk/~npfl/Publications/lgw+06.ps.gz (Changed URL of high-res
version
Cutting Curing and Canning Pork
Much of the meat butchered on farms for home use spoils before it can be eaten. Furthermore, much of it that does not spoil is so well cured that it is too salty to eat without first being soaked or par-boiled. This is due largely to lack of knowledge of good methods and practices that make for safety in both curing and canning. Most farmers make it a practice to cure and can their summer meat supply during the fall or winter. Both the farmer and his wife take an active interest in providing and preparing this supply of meat for summer use, both realizing that a balanced diet must include meat in some form. Then too, the farmer is entitled to use some of the good products on his own table and the meat animals rank among his best. With these conditions in mind, this circular is prepared to point out certain definite methods of cutting, curing, and canning which have proved successful both on farm and in the South Dakota State College abattoir
Form Factors from a Relativistic Dynamical Model of Pion Electroproduction
We obtain the electromagnetic form factors of the transition
by analyzing recent pion-electroproduction data using a fully relativistic
dynamical model. Special care is taken to satisfy Ward-Takahashi identities for
the Born term in the presence of form factors thereby allowing the use of
realistic electromagnetic form factors of the nucleon and pion. We parametrize
the dependence of the {\it bare} form factors by a
three-parameter form which is consistent with the asymptotic behavior inferred
from QCD. The parameters of the bare form factors are the
only free parameters of the model and are fitted to the differential
cross-section and multipole-analysis data up to (GeV/c) in the
-resonance region. This analysis emphasizes the significance of
the pion-cloud effects in the extraction of the resonance parameters.Comment: 9 pages, 5 figures, several small corrections, to be published in
Phys. Rev.
Conductances, transference numbers, and activity coefficients of chlorides of some high atomic rare earths in aqueous solution
The conductances, transference numbers, and activity coefficients of lanthanum chloride, samaric chloride, europic chloride, and ytterbic chloride were determined in order to test the present theories of electrolytic solutions as well as to make available accurate data on these useful properties for the above rare earth chlorides
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