7,980 research outputs found
The effect of various drugs on experimentally induced ulcers in immobilized rats
Experiments related to the importance of functional disorders in the central nervous system in connection with stomach diseases were performed on Wistar rats. Assuming that severe mental strains may be triggering factors for such disorders, testing of the effects of different drugs on experimentally induced ulcers in these rats was done. The immobilization method described by Bonfils was used. Particular importance was placed on the sex related difference which appeared
Parity Doublet Model applied to Neutron Stars
The Parity doublet model containing the SU(2) multiplets including the
baryons identified as the chiral partners of the nucleons is applied for
neutron star matter. The chiral restoration is analyzed and the maximum mass of
the star is calculated.Comment: Proceeding to the conference International Symposium on Exotic States
of Nuclear Matte
Impact of baryon resonances on the chiral phase transition at finite temperature and density
We study the phase diagram of a generalized chiral SU(3)-flavor model in
mean-field approximation. In particular, the influence of the baryon
resonances, and their couplings to the scalar and vector fields, on the
characteristics of the chiral phase transition as a function of temperature and
baryon-chemical potential is investigated. Present and future finite-density
lattice calculations might constrain the couplings of the fields to the
baryons. The results are compared to recent lattice QCD calculations and it is
shown that it is non-trivial to obtain, simultaneously, stable cold nuclear
matter.Comment: 18 pages, 7 figure
Research project Mauretania: Satellites as development aids
A general discussion is presented of how satellite images and ground surveys are used to define land use. Specifically it deals with the Tagant region in Mauretania, West Africa
Chiral Hadronic Mean Field Model including Quark Degrees of Freedom
In an approach inspired by Polyakov loop extended NJL models, we present a
nonlinear hadronic SU(3) sigma-omega mean field model augmented by quark
degrees of freedom. By introducing the effective Polyakov loop related scalar
field \Phi and an associated effective potential, the model includes all known
hadronic degrees of freedom at low temperatures and densities as well as a
quark phase at high temperatures and densities. Hadrons in the model exhibit a
finite volume in order to suppress baryons at high T and \mu. This ensures that
the right asymptotic degrees of freedom are attained for the description of
strongly interacting matter and allows to study the QCD phase diagram in a wide
range of temperatures and chemical potentials. Therefore, with this model it is
possible to study the phase transition of chiral restoration and deconfinement.
In this paper, the impact of quarks on the resulting phase diagram is shown.
The results from the chiral model are compared to recent data from lattice QCD.Comment: 25 pages, 10 figure
Electron capture to continuum in collisions of bare projectiles with Ne targets
Abstract. We have investigated the cusp resulting from electron capture to the continuum of 1.25-5 MeV m u- ' fully stripped hydrogen and oxygen as a function of the collision energy and the detector angular resolution B o. It is revealed that the characteristic cusp shape parameters depend strongly on the experimental resolution. Our experimental data are "pared with the second-order Born theory and the impulse approximation. Both theories mnhrm the 8, dependence of the shape parameters and gjve a reasonable descrip-lion of the cusp asymmetry. However, theory tends to overestimate the absolute cross sections, in particular in the case of oxygen. 1
In-medium vector meson masses in a Chiral SU(3) model
A significant drop of the vector meson masses in nuclear matter is observed
in a chiral SU(3) model due to the effects of the baryon Dirac sea. This is
taken into account through the summation of baryonic tadpole diagrams in the
relativistic Hartree approximation. The appreciable decrease of the in-medium
vector meson masses is due to the vacuum polarisation effects from the nucleon
sector and is not observed in the mean field approximation.Comment: 26 pages including 10 figures; the text has been modified for clarit
The Structure and Clustering of Lyman Break Galaxies
The number density and clustering properties of Lyman-break galaxies (LBGs)
are consistent with them being the central galaxies of the most massive dark
halos present at z~3. This conclusion holds in all currently popular
hierarchical models for structure formation, and is almost independent of the
global cosmological parameters. We examine whether the sizes, luminosities,
kinematics and star-formation rates of LBGs are also consistent with this
identification. Simple formation models tuned to give good fits to low redshift
galaxies can predict the distribution of these quantities in the LBG
population. The LBGs should be small (with typical half-light radii of 0.6-2
kpc/h), should inhabit haloes of moderately high circular velocity (180-290
km/s) but have low stellar velocity dispersions (70-120 km/s) and should have
substantial star formation rates (15-100 Msun/yr). The numbers here refer to
the predicted median values in the LBG sample of Adelberger et al. (1998); the
first assumes an Omega=1 universe and the second a flat universe with
Omega=0.3. For either cosmology these predictions are consistent with the
current (rather limited) observational data. Following the work of Kennicutt
(1998) we assume stars to form more rapidly in gas of higher surface density.
This predicts that LBG samples should preferentially contain objects with low
angular momentum, and so small size, for their mass. In contrast, samples of
damped Lyman alpha systems (DLSs), should be biased towards objects with large
angular momentum. Bright LBGs and DLSs may therefore form distinct populations,
with very different sizes and star formation rates, LBGs being smaller and more
metal-rich than DLSs of similar mass and redshift.Comment: 27 pages, 9 figures, MNRAS submitte
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