8,616 research outputs found
Buoyancy driven rotating boundary currents
The structure of boundary currents formed from intermediately dense water
introduced into a rotating, stably stratified, two-layer environment is
investigated in a series of laboratory experiments, performed for Froude
numbers ranging from 0.01 to 1. The thickness and streamwise velocity profiles
in quasi-steady currents are measured using a pH activated tracer (thymol blue)
and found to compare favorably to simplified analytic solutions and numerical
models. Currents flowing along sloping boundaries in a stratified background
exhibit robust stability at all experimental Froude numbers. Such stability is
in sharp contrast to the unequivocal instability of such currents flowing
against vertical boundaries, or of currents flowing along slopes in a uniform
background. The presence of a variety of wave mechanisms in the ambient medium
might account for the slower and wider observed structures and the stability of
the currents, by effecting the damping of disturbances through wave radiation.Comment: 9 pages with 2 figures to appear in Ann NYAS "Long range effects in
physics and astrophysics
Lipkin translational-symmetry restoration in the mean-field and energy-density-functional methods
Based on the 1960 idea of Lipkin, the minimization of energy of a
symmetry-restored mean-field state is equivalent to the minimization of a
corrected energy of a symmetry-broken state with the Peierls-Yoccoz mass. It is
interesting to note that the "unphysical" Peierls-Yoccoz mass, and not the true
mass, appears in the Lipkin projected energy. The Peierls-Yoccoz mass can be
easily calculated from the energy and overlap kernels, which allows for a
systematic, albeit approximate, restoration of translational symmetry within
the energy-density formalism. Analogous methods can also be implemented for all
other broken symmetries.Comment: 15 LaTeX pages, 8 eps figures, submitted to Journal of Physics
Aquarium fishes and their collection in the Great Barrier Reef Region
The size and nature of the aquarium fish industry in the Great
Barrier Reef Region makes it both economically .and ecologically important. The industry is expanding fast, yet little information is available
Where we are on : addendum to "Global neutrino data and recent reactor fluxes: status of three-flavour oscillation parameters"
In this addendum to arXiv:1103.0734 we consider the recent results from
long-baseline searches at the T2K and MINOS experiments and
investigate their implications for the mixing angle and the
leptonic Dirac CP phase . By combining the indication for a
non-zero value of coming from T2K data with global neutrino
oscillation data we obtain a significance for of about
with best fit points for normal
(inverted) neutrino mass ordering. These results depend somewhat on assumptions
concerning the analysis of reactor neutrino data.Comment: 5 pages, 2 figures and 1 tabl
Gamow-Teller transitions and deformation in the proton-neutron random phase approximation
We investigate reliability of Gamow-Teller transition strengths computed in
the proton-neutron random phase approximation, comparing with exact results
from diagonalization in full shell-model spaces. By allowing the
Hartree-Fock state to be deformed, we obtain good results for a wide variety of
nuclides, even though we do not project onto good angular momentum. We suggest
that deformation is as important or more so than pairing for Gamow-Teller
transitions.Comment: 8 pages, 5 figures; added references, clarified discussion with
regards to stabilit
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