233 research outputs found
Nucleation Rate of Hadron Bubbles in Baryon-Free Quark-Gluon Plasma
We evaluate the factor appearing in Langer's expression for the
nucleation rate extended to the case of hadron bubbles forming in zero baryon
number cooled quark-gluon plasma. We consider both the absence and presence of
viscosity and show that viscous effects introduce only small changes in the
value of Comment: 9 pages, revtex, no figures Full postscript version available at via
the WWW at http://nucth.physics.wisc.edu/preprints/ or by via from
ftp://nucth.physics.wisc.edu/pub/preprints/mad-nt-95-06.p
Formation of Two Component Bose Condensate During the Chemical Potential Curve Crossing
In this article we study the formation of the two modes Bose-Einstein
condensate and the correlation between them. We show that beyond the mean field
approximation the dissociation of a molecular condensate due to the chemical
potential curve crossing leads to the formation of two modes condensate. We
also show that these two modes are correlated in a two mode squeezed state.Comment: 10 page
Integrable Spin Chains on the Conformal Moose
We consider N=1, D=4 superconformal U(N)^{pq} Yang-Mills theories dual to
AdS_5xS^5/Z_pxZ_q orbifolds. We construct the dilatation operator of this
superconformal gauge theory at one-loop planar level. We demonstrate that a
specific sector of this dilatation operator can be thought of as the transfer
matrix for a two-dimensional statistical mechanical system, related to an
integrable SU(3) anti-ferromagnetic spin chain system, which in turn is
equivalent to a 2+1-dimensional string theory where the spatial slices are
discretized on a triangular lattice. This is an extension of the SO(6) spin
chain picture of N=4 super Yang-Mills theory. We comment on the integrability
of this N=1 gauge theory and hence the corresponding three-dimensional
statistical mechanical system, its connection to three-dimensional lattice
gauge theories, extensions to six-dimensional string theories, AdS/CFT type
dualities and finally their construction via orbifolds and brane-box models. In
the process we discover a new class of almost-BPS BMN type operators with large
engineering dimensions but controllably small anomalous corrections.Comment: 53 pages, 14 eps figures; Added reference
Photon-Photon and Pomeron-Pomeron Processes in Peripheral Heavy Ion Collisions
We estimate the cross sections for the production of resonances, pion pairs
and a central cluster of hadrons in peripheral heavy-ion collisions through
two-photon and double-pomeron exchange, at energies that will be available at
RHIC and LHC. The effect of the impact parameter in the diffractive reactions
is introduced, and imposing the condition for realistic peripheral collisions
we verify that in the case of very heavy ions the pomeron-pomeron contribution
is indeed smaller than the electromagnetic one. However, they give a
non-negligible background in the collision of light ions. This diffractive
background will be more important at RHIC than at LHC.Comment: 22 pages, 1 Postscript figures, 4 tables, to appear in Phys. Rev.
Hadronic properties of the S_{11}(1535) studied by electroproduction off the deuteron
Properties of excited baryonic states are investigated in the context of
electroproduction of baryon resonances off the deuteron. In particular, the
hadronic radii and the compositeness of baryon resonances are studied for
kinematic situations in which their hadronic reinteraction is the dominant
contribution. Specifically, we study the reaction at for kinematics in which the produced hadronic state reinteracts
predominantly with the spectator nucleon. A comparison of constituent quark
model and effective chiral Lagrangian calculations of the shows
substantial sensitivity to the structure of the produced resonance.Comment: 24 pages, 5 figure
Interstellar MHD Turbulence and Star Formation
This chapter reviews the nature of turbulence in the Galactic interstellar
medium (ISM) and its connections to the star formation (SF) process. The ISM is
turbulent, magnetized, self-gravitating, and is subject to heating and cooling
processes that control its thermodynamic behavior. The turbulence in the warm
and hot ionized components of the ISM appears to be trans- or subsonic, and
thus to behave nearly incompressibly. However, the neutral warm and cold
components are highly compressible, as a consequence of both thermal
instability in the atomic gas and of moderately-to-strongly supersonic motions
in the roughly isothermal cold atomic and molecular components. Within this
context, we discuss: i) the production and statistical distribution of
turbulent density fluctuations in both isothermal and polytropic media; ii) the
nature of the clumps produced by thermal instability, noting that, contrary to
classical ideas, they in general accrete mass from their environment; iii) the
density-magnetic field correlation (or lack thereof) in turbulent density
fluctuations, as a consequence of the superposition of the different wave modes
in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio
(MFR) in density fluctuations as they are built up by dynamic compressions; v)
the formation of cold, dense clouds aided by thermal instability; vi) the
expectation that star-forming molecular clouds are likely to be undergoing
global gravitational contraction, rather than being near equilibrium, and vii)
the regulation of the star formation rate (SFR) in such gravitationally
contracting clouds by stellar feedback which, rather than keeping the clouds
from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse
Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as
per referee's recommendation
Nitric oxide releasing-dendrimers: an overview
Platforms able to storage, release or scavenge NO in a controlled and specific manner is interesting for biological applications. Among the possible matrices for these purposes, dendrimers are excellent candidates for that. These molecules have been used as drug delivery systems and exhibit interesting properties, like the possibility to perform chemical modifications on dendrimers surface, the capacity of storage high concentrations of compounds of interest in the same molecule and the ability to improve the solubility and the biocompatibility of the compounds bonded to it. This review emphasizes the recent progress in the development and in the biological applications of different NO-releasing dendrimers and the nitric oxide release pathways in these compounds
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