65 research outputs found
Linking the hydrodynamic and kinetic description of a dissipative relativistic conformal theory
We use the entropy production variational method to associate a one particle
distribution function to the assumed known energy-momentum and entropy currents
describing a relativistic conformal fluid. Assuming a simple form for the
collision operator we find this one particle distribution function explicitly,
and show that this method of linking the hydro and kinetic description is a non
trivial generalization of Grad's ansatz. The resulting constitutive relations
are the same as in the conformal dissipative type theories discussed in J.
Peralta-Ramos and E. Calzetta, Phys. Rev. D {\bfseries 80}, 126002 (2009). Our
results may prove useful in the description of freeze-out in ultrarelativistic
heavy-ion collisions.Comment: v2: 23 pages, no figures, accepted in Phys. Rev.
Effect of boundary conditions on diffusion in two-dimensional granular gases
We analyze the influence of boundary conditions on numerical simulations of
the diffusive properties of a two dimensional granular gas. We show in
particular that periodic boundary conditions introduce unphysical correlations
in time which cause the coefficient of diffusion to be strongly dependent on
the system size. On the other hand, in large enough systems with hard walls at
the boundaries, diffusion is found to be independent of the system size. We
compare the results obtained in this case with Langevin theory for an elastic
gas. Good agreement is found. We then calculate the relaxation time and the
influence of the mass for a particle of radius in a sea of particles of
radius . As granular gases are dissipative, we also study the influence of
an external random force on the diffusion process in a forced dissipative
system. In particular, we analyze differences in the mean square velocity and
displacement between the elastic and inelastic cases.Comment: 15 figures eps figures, include
12mm line survey of the dense molecular gas towards the W28 field TeV gamma-ray sources
We present 12mm Mopra observations of dense molecular gas towards the W28
supernova remnant (SNR) field. The focus is on the dense molecular gas towards
the TeV gamma-ray sources detected by the H.E.S.S. telescopes, which likely
trace the cosmic-rays from W28 and possibly other sources in the region. Using
the NH3 inversion transitions we reveal several dense cores inside the
molecular clouds, the majority of which coincide with high-mass star formation
and HII regions, including the energetic ultra-compact HII region G5.89-0.39. A
key exception to this is the cloud north east of W28, which is well-known to be
disrupted as evidenced by clusters of 1720MHz OH masers and broad CO line
emission. Here we detect broad NH3, up to the (9,9) transition, with linewidths
up to 16 km/s. This broad NH3 emission spatially matches well with the TeV
source HESS J1801-233 and CO emission, and its velocity dispersion distribution
suggests external disruption from the W28 SNR direction. Other lines are
detected, such as HC3N and HC5N, H2O masers, and many radio recombination
lines, all of which are primarily found towards the southern high-mass star
formation regions. These observations provide a new view onto the internal
structures and dynamics of the dense molecular gas towards the W28 SNR field,
and in tandem with future higher resolution TeV gamma-ray observations will
offer the chance to probe the transport of cosmic-rays into molecular clouds.Comment: 18 pages, 10 figures, 5 tables, accepted for publication in MNRAS.
Online appendices containing additional molecular line: fit parameters, maps,
PV plots & spectra, will be available through MNRA
Direct Imaging of Lipid-Ion Network Formation under Physiological Conditions by Frequency Modulation Atomic Force Microscopy
An adolescent with both Wegener's Granulomatosis and chronic blastomycosis
We report a case of Wegener's Granulomatosis (WG) associated with blastomycosis. This appears to be the first case report of WG co-existing with a tissue proven blastomycosis infection. The temporal correlation of the two conditions suggests that blastomycosis infection (and therefore possibly other fungal infections), may trigger the systemic granulomatous vasculitis in a predisposed individual; a provocative supposition warranting further study
Multi-pion correlations in high energy collisions
Any-order pion inclusive distribution for a chaotic source in high energy
collisions are given which can be used in both theory and experiment to analyze
any-order pion interferometry. Multi-pion correlations effects on two-pion and
three-pion interferometry are discussed.Comment: Eq.(25) and Eq.(26) are correcte
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