6,079 research outputs found
The correlation of VLF propagation variations with atmospheric planetary-scale waves
Variations in the received daytime phase of long distance, cesium-controlled, VLF transmission were compared to the height variations of the 10-mb isobaric surface during the first three months of 1965 and 1969. The VLF phase values are also compared to height variations of constant electron densities in the E-region and to variations of f-min which have been shown to be well correlated with planetary-scale variations in the stratosphere by Deland and Cavalieri (1973). The VLF phase variations show good correlation with these previous ionospheric measurements and with the 10-mb surfaces. The planetary scale waves in the stratosphere are shown to be travelling on the average eastward in 1965 and westward in 1969. These correlations are interpreted as due to the propagation of travelling planetary scale waves with westward tilted wave fronts. Upward energy transport due to the vertical structure of those waves is also discussed. These correlations provide further evidence for the coupling between the lower ionosphere at about 70 km altitude (the daytime VLF reflection height and the stratosphere, and they demonstrate the importance of planetary wave phenomena to VLF propagation
Time evolution of the chiral phase transition during a spherical expansion
We examine the non-equilibrium time evolution of the hadronic plasma produced
in a relativistic heavy ion collision, assuming a spherical expansion into the
vacuum. We study the linear sigma model to leading order in a large-
expansion. Starting at a temperature above the phase transition, the system
expands and cools, finally settling into the broken symmetry vacuum state. We
consider the proper time evolution of the effective pion mass, the order
parameter , and the particle number distribution. We
examine several different initial conditions and look for instabilities
(exponentially growing long wavelength modes) which can lead to the formation
of disoriented chiral condensates (DCCs). We find that instabilities exist for
proper times which are less than 3 fm/c. We also show that an experimental
signature of domain growth is an increase in the low momentum spectrum of
outgoing pions when compared to an expansion in thermal equilibrium. In
comparison to particle production during a longitudinal expansion, we find that
in a spherical expansion the system reaches the ``out'' regime much faster and
more particles get produced. However the size of the unstable region, which is
related to the domain size of DCCs, is not enhanced.Comment: REVTex, 20 pages, 8 postscript figures embedded with eps
Dissipative Field Theory with Caldeira-Leggett Method and its Application to Disoriented Chiral Condensation
The effective field theory including the dissipative effect is developed
based on the Caldeira-Leggett theory at the classical level. After the
integration of the small field fluctuations considered as the field radiation,
the integro-differential field equation is given and shown to include the
dissipative effects. In that derivation, special cares should be taken for the
boundary condition of the integration. Application to the linear sigma model is
given, and the decay process of the chiral condensate is calculated with it,
both analytically in the linear approximation and numerically. With these
results, we discuss the stability of chiral condensates within the quenched
approximation.Comment: 16pages, ReV-Te
Lifetime of a Disoriented Chiral Condensate
The lifetime of a disoriented chiral condensate formed within a heat bath of
pions is calculated assuming temperatures and densities attainable at present
and future heavy-ion colliders. A generalization of the reduction formula to
include coherent states allows us to derive a formula for the decay rate. We
predict the half-life to be between 4 and 7 fm/c, depending on the assumed pion
density. We also calculate the lifetime in the presence of higher resonances
and baryons, which shortens the lifetime by at most 20%.Comment: 9 pages, 3 figures, REVTeX, Eq. (3) modifie
Viscosity and the Soft Ridge at RHIC
Correlation studies exhibit a ridge-like feature in rapidity and azimuthal
angle, with and without a jet trigger. We ask whether the feature in
untriggered correlations can be a consequence of transverse flow and viscous
diffusion.Comment: Proc. Quark Matter 2008, Jaipur, Indi
2-Benzyl-myo-inositol monohydrate
The title structure, C13H18O6·H2O, contains two independent 2-benzyl-myo-inositol and water molecules. In the crystal, the molecules are strongly hydrogen bonded into an infinite two dimensional network utilizing all OH protons
Mental health of Indigenous Australians: a review of findings from community surveys
Objective: To assemble what is known about the mental health of Indigenous Australians from community surveys. Data sources: A systematic search was carried out of publications and data sources since 2000 using PubMed, PsycINFO, Australian Medical Index, the National Library of Australia and datasets known to the authors.
Study selection: Surveys had to involve representative sampling of a population, identify Aboriginal and Torres Strait Islander people and include a measure of mental health.
Data extraction: 11 surveys were found. Data were extracted on prevalence rates for Indigenous people by age and sex, along with comparison data from the general population, where available. Data synthesis: Across seven studies, Indigenous adults were consistently found to have a higher prevalence of self-reported psychological distress than the general community. However, two studies of Indigenous adolescents did not find a higher prevalence of psychological distress. Two surveys of parents and carers of Indigenous children and adolescents found a higher prevalence of behaviour problems. Conclusions: There is an inequality in mental health between Indigenous and non-Indigenous Australians that starts from an early age. This needs to be a priority for research, preventive action and health services
Experimental Assembly and Sterilization Laboratory /EASL/ operations - Phase I
Facility description and operations for assembly and sterilization - microbiological testin
J/Psi suppression in colliding nuclei: statistical model analysis
We consider the suppression at a high energy heavy ion collision. An
ideal gas of massive hadrons in thermal and chemical equilibrium is formed in
the central region. The finite-size gas expands longitudinally in accordance
with Bjorken law. The transverse expansion in a form of the rarefaction wave is
taken into account. We show that suppression in such an environment,
when combined with the disintegration in nuclear matter, gives correct
evaluation of NA38 and NA50 data in a broad range of initial energy densities.Comment: 14 pages, 13 figures. Accepted for publication in Phys. Rev.
Charmonium suppression from purely geometrical effects
The extend to which geometrical effects contribute to the production and
suppression of the and minijet pairs in general is
investigated for high energy heavy ion collisions at SPS, RHIC and LHC
energies. For the energy range under investigation, the geometrical effects
referred to are shadowing and anti-shadowing, respectively. Due to those
effects, the parton distributions in nuclei deviate from the naive
extrapolation from the free nucleon result; . The strength
of the shadowing/anti-shadowing effect increases with the mass number. The
consequences of gluonic shadowing effects for the distribution of
's at GeV, GeV and TeV are
calculated for some relevant combinations of nuclei, as well as the
distribution of minijets at midrapidity for in the final state.Comment: corrected some typos, improved shadowing ratio
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