7,011 research outputs found
Homogeneous geodesics of non-unimodular Lorentzian Lie groups and naturally reductive Lorentzian spaces in dimension three
We determine, for all three-dimensional non-unimodular Lie groups equipped
with a Lorentzian metric, the set of homogeneous geodesics through a point.
Together with the results of [C] and [CM2], this leads to the full
classification of three-dimensional Lorentzian g.o. spaces and naturally
reductive spaces
Multiple solutions of coupled-cluster equations for PPP model of [10]annulene
Multiple (real) solutions of the CC equations (corresponding to the CCD, ACP
and ACPQ methods) are studied for the PPP model of [10]annulene, C_{10}H_{10}.
The long-range electrostatic interactions are represented either by the
Mataga--Nishimoto potential, or Pople's R^{-1} potential. The multiple
solutions are obtained in a quasi-random manner, by generating a pool of
starting amplitudes and applying a standard CC iterative procedure combined
with Pulay's DIIS method. Several unexpected features of these solutions are
uncovered, including the switching between two CCD solutions when moving
between the weakly and strongly correlated regime of the PPP model with Pople's
potential.Comment: 5 pages, 4 figures, RevTeX
Medicaid as an Investment in Children: What is the Long-Term Impact on Tax Receipts?
We use administrative data from the IRS to examine the long-term impact of childhood Medicaid expansions. We use eligibility variation by cohort and state that we can relate to outcomes graphically. We find that children with greater Medicaid eligibility paid more in cumulative taxes by age 28. They collected less in EITC payments, and the women had higher cumulative wages. Our estimates imply that the government will recoup 56 cents of each dollar spent on childhood Medicaid by the time these children reach age 60. This return does not include estimated private gains from increased college attendance and decreased mortality
Systematic gas gain measurements and Penning energy transfer rates in Ne-CO2 mixtures
In Ne-CO2 mixtures, excitation energy of Ne atom can be used to ionize CO2 molecule by the mechanisms called Penning transfers. In the present work, we have measured the gas gain systematically in various Ne-CO2 mixtures (Ne + 0 : 6-60 % CO2) at 0.4, 0.8, 1.2, 1.8 atm. The experimental data have been fitted to investigate the Penning energy transfer rates and the secondary processes playing a role in avalanche formations.Ministry of Energy & Natural Resources - Turkey - 2013 TAEK CERN-A5.H2.P1.01-23Polish National Science Centre - DEC-2013/10/M/ST7/0056
-like maps with various instabilities of acim's
This paper generalizes the results of [13] and then provides an interesting
example. We construct a family of -like maps with a turning fixed
point having slope on one side and on the other. Each has an
absolutely continuous invariant measure . Depending on whether
is larger, equal or smaller than 1, we show that
the limit of is a singular measure, a combination of singular and
absolutely continuous measure or an absolutely continuous measure,
respectively. It is known that the invariant density of a single piecewise
expanding map has a positive lower bound on its support. In Section 4 we give
an example showing that in general, for a family of piecewise expanding maps
with slopes larger than 2 in modulus and converging to a piecewise expanding
map, their invariant densities do not necessarily have a positive lower bound
on the support.Comment: 16 papges, 3 figure
Isocaling and the Symmetry Energy in the Multifragmentation Regime of Heavy Ion Collisions
The ratio of the symmetry energy coefficient to temperature, , in
Fermi energy heavy ion collisions, has been experimentally extracted as a
function of the fragment atomic number using isoscaling parameters and the
variance of the isotope distributions. The extracted values have been compared
to the results of calculations made with an Antisymmetrized Molecular Dynamics
(AMD) model employing a statistical decay code to account for deexcitation of
excited primary fragments. The experimental values are in good agreement with
the values calculated but are significantly different from those characterizing
the yields of the primary AMD fragments.Comment: 12 pages, 6 figure
An experimental survey of the production of alpha decaying heavy elements in the reactions of U +Th at 7.5-6.1 MeV/nucleon
The production of alpha particle decaying heavy nuclei in reactions of
7.5-6.1 MeV/nucleon U +Th has been explored using an in-beam
detection array composed of YAP scintillators and gas ionization chamber-Si
telescopes. Comparisons of alpha energies and half-lives for the observed
products with those of the previously known isotopes and with theoretically
predicted values indicate the observation of a number of previously unreported
alpha emitters. Alpha particle decay energies reaching as high as 12 MeV are
observed. Many of these are expected to be from decay of previously unseen
relatively neutron rich products. While the contributions of isomeric states
require further exploration and specific isotope identifications need to be
made, the production of heavy isotopes with quite high atomic numbers is
suggested by the data.Comment: 12 pages, 12 figure
A splitting theorem for Kahler manifolds whose Ricci tensors have constant eigenvalues
It is proved that a compact Kahler manifold whose Ricci tensor has two
distinct, constant, non-negative eigenvalues is locally the product of two
Kahler-Einstein manifolds. A stronger result is established for the case of
Kahler surfaces. Irreducible Kahler manifolds with two distinct, constant
eigenvalues of the Ricci tensor are shown to exist in various situations: there
are homogeneous examples of any complex dimension n > 1, if one eigenvalue is
negative and the other positive or zero, and of any complex dimension n > 2, if
the both eigenvalues are negative; there are non-homogeneous examples of
complex dimension 2, if one of the eigenvalues is zero. The problem of
existence of Kahler metrics whose Ricci tensor has two distinct, constant
eigenvalues is related to the celebrated (still open) Goldberg conjecture.
Consequently, the irreducible homogeneous examples with negative eigenvalues
give rise to complete, Einstein, strictly almost Kahler metrics of any even
real dimension greater than 4.Comment: 18 pages; final version; accepted for publication in International
Journal of Mathematic
The Quantum Nature of a Nuclear Phase Transition
In their ground states, atomic nuclei are quantum Fermi liquids. At finite
temperatures and low densities, these nuclei may undergo a phase change similar
to, but substantially different from, a classical liquid gas phase transition.
As in the classical case, temperature is the control parameter while density
and pressure are the conjugate variables. At variance with the classical case,
in the nucleus the difference between the proton and neutron concentrations
acts as an additional order parameter, for which the symmetry potential is the
conjugate variable. Different ratios of the neutron to proton concentrations
lead to different critical points for the phase transition. This is analogous
to the phase transitions occurring in He-He liquid mixtures. We
present experimental results which reveal the N/Z dependence of the phase
transition and discuss possible implications of these observations in terms of
the Landau Free Energy description of critical phenomena.Comment: 5 pages, 4 figure
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