668 research outputs found
Review of \u3cem\u3eMafias on the Move: How Organized Crime Conquers New Territories,\u3c/em\u3e by Federico Varese
P-Wave Polarization of the -Meson and the Dilepton Spectrum in Dense Matter
We study the -wave polarization operator of the -meson due to interactions via the (1720) and resonances and compute
the corresponding production rate for -pairs at finite temperature and
baryon density. At high baryon density we find a significant shift of the
spectrum to lower invariant masses.Comment: 22 pages, 8 Postscript figures, uses article.sty, epsf.sty,
epsfig.st
Hamiltonian Flow Equations for the Lipkin Model
We derive Hamiltonian flow equations giving the evolution of the Lipkin
Hamiltonian to a diagonal form using continuous unitary transformations. To
close the system of flow equations, we present two different schemes. First we
linearize an operator with three pairs of creation and destruction operators by
reducing it to the component of the quasi spin. We obtain the well known
RPA-result in the limit of large particle number. In the second scheme we
introduce a new operator which improves the resulting spectrum considerably
especially for few particles.Comment: 10 pages, 2 eps figures, uses article.sty, epsfig.st
An “Untrammeled Right”? The McCarran Immigration Subcommittee and the Origins of Presidential Authority to Suspend and Restrict Alien Entry Under §1182(f)
The language of Section 212(e) of the 1952 Immigration and Nationality Act, 8 U.S.C. §1182(f), contains a sweeping authorization of presidential discretion to suspend and restrict alien entry into the United States. Senator Pat McCarran (D-NV) first introduced the subsection in 1950 as part of the omnibus immigration bill drafted by his Judiciary Committee’s immigration subcommittee. The specific origins of the language and the original intent behind the subsection remain missing pieces in the extensive scholarly literature on the 1952 INA and legislative history as explored by the courts. This article reveals that the subcommittee modeled the subsection on the sixth proviso of the 1917 Immigration Act, the May 1918 Wartime Measure, and a selective interpretation of Supreme Court precedent. The article reveals further that the original intent behind the subsection was to close perceived loopholes in existing law enabling entry by displaced persons and Communist governmental officials
Constraints on vector mesons with finite momentum in nuclear matter
Using the QCD operator product expansion, we derive the real part of the transverse and longitudinal vector-vector correlation function with the quantum numbers of the rho and omega mesons to leading order in density and three momentum (q^2) for energy . The operator product expansion provides, through the Borel transformed energy dispersion relation, a model independent constraint for the momentum dependence of the vector meson spectral density in nuclear matter. Existing model calculations for the dispersion effect of the rho meson, where the vector-meson nucleon scattering amplitude is obtained by resonance saturation in the s-channel, in general violate this constraint. We trace this to an inconsistent choice for the form factor of the vertex. With a consistent choice, where both the form factor and the coupling constant are obtained from the Bonn potential, the contribution of the is substantially reduced and we find good agreement with the constraint equation. We briefly comment on the implications of our result for attempts to interpret the enhancement of low-mass dileptons in heavy-ion collisions
Topo-Geometric Filtration Scheme for Geometric Active Contours and Level Sets: Application to Cerebrovascular Segmentation
One of the main problems of the existing methods for the
segmentation of cerebral vasculature is the appearance in the segmentation
result of wrong topological artefacts such as the kissing vessels.
In this paper, a new approach for the detection and correction of such
errors is presented. The proposed technique combines robust topological
information given by Persistent Homology with complementary geometrical
information of the vascular tree. The method was evaluated on 20
images depicting cerebral arteries. Detection and correction success rates
were 81.80% and 68.77%, respectively
Medical screening in dental settings: a qualitative study of the views of authorities and organizations
Effective Nucleon-Nucleon Interaction and Fermi Liquid Theory
We present two novel relations between the quasiparticle interaction in
nuclear matter and the unique low momentum nucleon-nucleon interaction in
vacuum. These relations provide two independent constraints on the Fermi liquid
parameters of nuclear matter. Moreover, the new constraints define two
combinations of Fermi liquid parameters, which are invariant under the
renormalization group flow in the particle-hole channels. Using empirical
values for the spin-independent Fermi liquid parameters, we are able to compute
the major spin-dependent ones by imposing the new constraints as well as the
Pauli principle sum rules.Comment: 4 pages, 5 figures, in Proc. 11th International Conference on Recent
Progress in Many-Body Theories, Manchester, UK, July 9-13, 200
Studying the properties in pA collisions via the decay
Within transport calculations we study the production and decay of
-mesons in reactions at COSY energies including elastic and
inelastic rescattering, the Dalitz decay
as well as rescattering. The resulting invariant mass
distributions indicate that in-medium modifications of the -meson may
be observed experimentally.Comment: 5 pages, espcrc2-style, including 5 ps-figure
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