40 research outputs found
The Universe out of an Elementary Particle?
We consider a model of an elementary particle as a 2 + 1 dimensional brane
evolving in a 3 + 1 dimensional space. Introducing gauge fields that live in
the brane as well as normal surface tension can lead to a stable "elementary
particle" configuration. Considering the possibility of non vanishing vacuum
energy inside the bubble leads, when gravitational effects are considered, to
the possibility of a quantum decay of such "elementary particle" into an
infinite universe. Some remarkable features of the quantum mechanics of this
process are discussed, in particular the relation between possible boundary
conditions and the question of instability towards Universe formation is
analyzed
On the water-bag model of dispersionless KP hierarchy
We investigate the bi-Hamiltonian structure of the waterbag model of dKP for
two component case. One can establish the third-order and first-order
Hamiltonian operator associated with the waterbag model. Also, the dispersive
corrections are discussed.Comment: 19 page
The r-process nucleosynthesis: a continued challenge for nuclear physics and astrophysics
The identification of the astrophysical site and the specific conditions in
which r-process nucleosynthesis takes place remain unsolved mysteries of
astrophysics. The present paper emphasizes some important future challenges
faced by nuclear physics in this problem, particularly in the determination of
the radiative neutron capture rates by exotic nuclei close to the neutron drip
line and the fission probabilities of heavy neutron-rich nuclei. These
quantities are particularly relevant to determine the composition of the matter
resulting from the decompression of initially cold neutron star matter. New
detailed r-process calculations are performed and the final composition of
ejected inner and outer neutron star crust material is estimated. We discuss
the impact of the many uncertainties in the astrophysics and nuclear physics on
the final composition of the ejected matter. The similarity between the
predicted and the solar abundance pattern for A > 140 nuclei as well as the
robustness of the prediction with varied input parameters makes this scenario
one of the most promising that deserves further exploration.Comment: 8 pages, contribution to the Nuclei in the Cosmos Conference, to
appear in Nucl. Phys.
Long-Term Cultured Hairy Roots of Chicory—A Rich Source of Hydroxycinnamates and 8-Deoxylactucin Glucoside
Inflammation and disintegration of intestinal villi in an experimental model for Vibrio parahaemolyticus-induced diarrhea.
Vibrio parahaemolyticus is a leading cause of seafood-borne gastroenteritis in many parts of the world, but there is limited knowledge of the pathogenesis of V. parahaemolyticus-induced diarrhea. The absence of an oral infection-based small animal model to study V. parahaemolyticus intestinal colonization and disease has constrained analyses of the course of infection and the factors that mediate it. Here, we demonstrate that infant rabbits oro-gastrically inoculated with V. parahaemolyticus develop severe diarrhea and enteritis, the main clinical and pathologic manifestations of disease in infected individuals. The pathogen principally colonizes the distal small intestine, and this colonization is dependent upon type III secretion system 2. The distal small intestine is also the major site of V. parahaemolyticus-induced tissue damage, reduced epithelial barrier function, and inflammation, suggesting that disease in this region of the gastrointestinal tract accounts for most of the diarrhea that accompanies V. parahaemolyticus infection. Infection appears to proceed through a characteristic sequence of steps that includes remarkable elongation of microvilli and the formation of V. parahaemolyticus-filled cavities within the epithelial surface, and culminates in villus disruption. Both depletion of epithelial cell cytoplasm and epithelial cell extrusion contribute to formation of the cavities in the epithelial surface. V. parahaemolyticus also induces proliferation of epithelial cells and recruitment of inflammatory cells, both of which occur before wide-spread damage to the epithelium is evident. Collectively, our findings suggest that V. parahaemolyticus damages the host intestine and elicits disease via previously undescribed processes and mechanisms