Multidimensional quantum solitons with nondegenerate parametric interactions: Photonic and Bose-Einstein condensate environments

We consider the quantum theory of three fields interacting via parametric and repulsive quartic couplings. This can be applied to treat photonic chi((2)) and chi((3)) interactions, and interactions in atomic Bose-Einstein condensates or quantum Fermi gases, describing coherent molecule formation together with a-wave scattering. The simplest two-particle quantum solitons or bound-state solutions of the idealized Hamiltonian, without a momentum cutoff, are obtained exactly. They have a pointlike structure in two and three dimensions-even though the corresponding classical theory is nonsingular. We show that the solutions can be regularized with a momentum cutoff. The parametric quantum solitons have much more realistic length scales and binding energies than chi((3)) quantum solitons, and the resulting effects could potentially be experimentally tested in highly nonlinear optical parametric media or interacting matter-wave systems. N-particle quantum solitons and the ground state energy are analyzed using a variational approach. Applications to atomic/molecular Bose-Einstein condensates (BEC's) are given, where we predict the possibility of forming coupled BEC solitons in three space dimensions, and analyze superchemistry dynamics

Haemolysins in Vibrio species

Many Vibrio species are pathogenic to humans, and/or marine vertebrates and invertebrates. The pathogenic species produce various virulence factors including enterotoxin, haemolysin, cytotoxin, protease, lipase, phospholipase, siderophore, adhesive factor and/or haemagglutinins. Haemolysin, which is an exotoxin that lyses erythrocyte membranes with the liberation of haemoglobin, is arguably the most widely distributed toxin among pathogenic vibrios and exerts various roles in the infection process. Haemolysins act on erythrocytes membranes thus lysing the cells which leads to the freeing up of the iron-binding proteins namely haemoglobin, transferrin and lactoferrin. This iron can then be picked up by various siderophores, and is subsequently taken up through receptors in the cell membrane. In many cases, the pore-forming activity of haemolysin is not restricted to erythrocytes, but extends to a wide range of other cell types including mast cells, neutrophils, and polymorphonuclear cells, and enhances virulence by causing tissue damage. There are four representative haemolysin families in Vibrio spp., including the TDH (thermostable direct haemolysin) family, the HlyA (E1 Tor haemolysin) family, the TLH (thermolabile haemolysin) family and the δ-VPH (thermostable haemolysin) family. Some haemolysins, for example, TDH of Vibrio parahaemolyticus and HlyA of Vibrio cholerae have been studied extensively, and are closely associated with virulence. However, the role of some haemolysins, e.g. TLH and δ-VPH are unclear, and await the outcome of further research