23,143 research outputs found
Thermal Model Analysis of Particle Ratios at GSI Ni-Ni Experiments Using Exact Strangeness Conservation
The production of hadrons in Ni-Ni at the GSI is considered in a hadronic gas
model with chemical equilibrium. Special attention is given to the abundance of
strange particles which are treated using the exact conservation of
strangeness. It is found that all the data can be described using a temperature
T = 70 pm 10 MeV and a baryon chemical potential mu_B = 720 pm 20 MeV.Comment: Revtex, 7 pages, 3 figures in postscript forma
Properties of Gamma-Ray Burst Time Profiles Using Pulse Decomposition Analysis
The time profiles of many gamma-ray bursts consist of distinct pulses, which
offers the possibility of characterizing the temporal structure of these bursts
using a relatively small set of pulse shape parameters. This pulse
decomposition analysis has previously been performed on a small sample of
bright long bursts using binned data from BATSE, which comes in several data
types, and on a sample of short bursts using the BATSE Time-Tagged Event (TTE)
data type. We have developed an interactive pulse-fitting program using the
phenomenological pulse model of Norris, et al. and a maximum-likelihood fitting
routine. We have used this program to analyze the Time-to-Spill (TTS) data for
all bursts observed by BATSE up through trigger number 2000, in all energy
channels for which TTS data is available. We present statistical information on
the attributes of pulses comprising these bursts, including relations between
pulse characteristics in different energy channels and the evolution of pulse
characteristics through the course of a burst. We carry out simulations to
determine the biases that our procedures may introduce. We find that pulses
tend to have shorter rise times than decay times, and tend to be narrower and
peak earlier at higher energies. We also find that pulse brightness, pulse
width, and pulse hardness ratios do not evolve monotonically within bursts, but
that the ratios of pulse rise times to decay times tend to decrease with time
within bursts.Comment: 40 pages, 19 figures. Submitted to Astrophysical Journal. PostScript
and PDF with un-bitmapped figures available at
http://www.slac.stanford.edu/pubs/slacpubs/8000/slac-pub-8364.html .
Accompanying paper astro-ph/0002218 available at
http://www.slac.stanford.edu/pubs/slacpubs/8000/slac-pub-8365.htm
Direct Use of Low Enthalpy Deep Geothermal Resources in the East African Rift Valley
Geothermal energy is already harnessed across East Africa to provide hundreds of megawatts of electricity, with significant plans for future expansion towards generation at the gigawatt scale. This power generation utilizes the high steam temperatures (typically more than 200 °C) that are available in several locations in Kenya, Ethiopia and elsewhere. The presence of these high enthalpy resources has deflected attention from the often attractive low and medium enthalpy resources present across a more extensive portion of the region. Geothermally heated water at cooler temperatures (less than 90 °C) could be widely produced by drilling shallower and cheaper boreholes than those required for power production. This low enthalpy resource could be widely exploitable throughout the Rift Valley, offering a low carbon, sustainable, reliable and commercially competitive source of heating, drying and cooling (via absorption chillers) to local farmers and growers, and for low temperature commercial and industrial uses. Applications of this type would displace expensive fossil fuels, reducing costs and carbon emissions as well as improving the region’s energy and food security. The power input for pump systems can be accommodated by relatively small generators, so direct heat projects could be beneficial to consumers in areas with no grid access
Renal fibrosis in feline chronic kidney disease: known mediators and mechanisms of injury
Chronic kidney disease (CKD) is a common medical condition of ageing cats. In most cases the underlying aetiology is unknown, but the most frequently reported pathological diagnosis is renal tubulointerstitial fibrosis. Renal fibrosis, characterised by extensive accumulation of extra-cellular matrix within the interstitium, is thought to be the final common pathway for all kidney diseases and is the pathological lesion best correlated with function in both humans and cats. As a convergent pathway, renal fibrosis provides an ideal target for the treatment of CKD and knowledge of the underlying fibrotic process is essential for the future development of novel therapies. There are many mediators and mechanisms of renal fibrosis reported in the literature, of which only a few have been investigated in the cat. This article reviews the process of renal fibrosis and discusses the most commonly cited mediators and mechanisms of progressive renal injury, with particular focus on the potential significance to feline CKD
The Interference Term between the Spin and Orbital Contributions to M1 Transitions
We study the cross-correlation between the spin and orbital parts of magnetic
dipole transitions M1 in both isoscalar and isovector channels. In particular,
we closely examine certain cases where is very close to , implying a cancellation of the summed
interference terms. We gain some insight into this problem by considering
special cases approaching the SU(3) limit, and by examining the behaviour of
single-particle transitions at the beginning and towards the end of the s-d
shell.Comment: 9 pages of latex file and no figure
Nonabelian density functional theory
Given a vector space of microscopic quantum observables, density functional
theory is formulated on its dual space. A generalized Hohenberg-Kohn theorem
and the existence of the universal energy functional in the dual space are
proven. In this context ordinary density functional theory corresponds to the
space of one-body multiplication operators. When the operators close under
commutation to form a Lie algebra, the energy functional defines a Hamiltonian
dynamical system on the coadjoint orbits in the algebra's dual space. The
enhanced density functional theory provides a new method for deriving the group
theoretic Hamiltonian on the coadjoint orbits from the exact microscopic
Hamiltonian.Comment: 1 .eps figur
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