729 research outputs found
Spectral weight function for the half-filled Hubbard model: a singular value decomposition approach
The singular value decomposition technique is used to reconstruct the
electronic spectral weight function for a half-filled Hubbard model with
on-site repulsion from Quantum Monte Carlo data. A two-band structure
for the single-particle excitation spectrum is found to persist as the lattice
size exceeds the spin-spin correlation length. The observed bands are flat in
the vicinity of the points in the Brillouin zone, in
accordance with experimental data for high-temperature superconducting
compounds.Comment: 4 pages, Revtex
The inverse Laplace transform as the ultimate tool for transverse mass spectra
New high statistics data from the second generation of ultrarelativistic
heavy-ion experiments open up new possibilities in terms of data analysis. To
fully utilize the potential we propose to analyze the -spectra of
hadrons using the inverse Laplace transform. The problems with its inherent
ill-definedness can be overcome and several applications in other fields like
biology, chemistry or optics have already shown its feasability. Moreover, the
method also promises to deliver upper bounds on the total information content
of the spectra, which is of big importance for all other means of analysis.
Here we compute several Laplace inversions from different thermal scenarios,
both analytically and numerically, to test the efficiency of the method.
Especially the case of a two component structure, related to a possible first
order phase transition to a quark gluon plasma, is closer investigated and it
is shown that at least a signal to noise ratio of is necessary to
resolve two individual components.Comment: 13 pages (PostScript, including figures), BNL-NTHES
Beauvericin and Enniatins: In Vitro Intestinal Effects
Food and feed contamination by emerging mycotoxins beauvericin and enniatins is a worldwide health problem and a matter of great concern nowadays, and data on their toxicological behavior are still scarce. As ingestion is the major route of exposure to mycotoxins in food and feed, the gastrointestinal tract represents the first barrier encountered by these natural contaminants and the first structure that could be affected by their potential detrimental effects. In order to perform a complete and reliable toxicological evaluation, this fundamental site cannot be disregarded. Several in vitro intestinal models able to recreate the different traits of the intestinal environment have been applied to investigate the various aspects related to the intestinal toxicity of emerging mycotoxins. This review aims to depict an overall and comprehensive representation of the in vitro intestinal effects of beauvericin and enniatins in humans from a species-specific perspective. Moreover, information on the occurrence in food and feed and notions on the regulatory aspects will be provided
Time Delay and Time Advance in Resonance Theory
We propose a theory of the resonance-antiresonance scattering process which
differs considerably from the classical one (the Breit-Wigner theory), which is
commonly used in the phenomenological analysis. Here both resonances and
antiresonances are described in terms of poles of the scattering amplitude: the
resonances by poles in the first quadrant while the antiresonances by poles in
the fourth quadrant of the complex angular momentum plane. The latter poles are
produced by non-local potentials, which derive from the Pauli exchange forces
acting among the nucleons or the quarks composing the colliding particles.Comment: 30 pages, 7 figure
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