Selection-mutation balance models with epistatic selection

We present an application of birth-and-death processes on configuration spaces to a generalized mutation4 selection balance model. The model describes the aging of population as a process of accumulation of mu5 tations in a genotype. A rigorous treatment demands that mutations correspond to points in abstract spaces. 6 Our model describes an infinite-population, infinite-sites model in continuum. The dynamical equation which 7 describes the system, is of Kimura-Maruyama type. The problem can be posed in terms of evolution of states 8 (differential equation) or, equivalently, represented in terms of Feynman-Kac formula. The questions of interest 9 are the existence of a solution, its asymptotic behavior, and properties of the limiting state. In the non-epistatic 10 case the problem was posed and solved in [Steinsaltz D., Evans S.N., Wachter K.W., Adv. Appl. Math., 2005, 11 35(1)]. In our model we consider a topological space X as the space of positions of mutations and the influence of epistatic potential

Created-by-current states in long Josephson junctions

Critical curves "critical current - external magnetic field" of long Josephson junctions with inhomogeneity and variable width are studied. We demonstrate the existence of the regions of magnetic field where some fluxon states are stable only, if the external current through the junction is different from zero. Position and size of such regions depend on length of the junction, its geometry, parameters of inhomogeneity and form of the junction. The noncentral (left and right) pure fluxon states are appeared in the inhomogeneous Josephson junction with increase in the junction length. We demonstrate new bifurcation points with change in width of the inhomogeneity and amplitude of the Josephson current through the inhomogeneity.Comment: 7 pages, 8 figure

Sympathetic cooling of polyatomic molecules with S-state atoms in a magnetic trap

We present a rigorous theoretical study of low-temperature collisions of polyatomic molecular radicals with ^1S_0 atoms in the presence of an external magnetic field. Accurate quantum scattering calculations based on ab initio and scaled interaction potentials show that collision-induced spin relaxation of the prototypical organic molecule CH_2(X^3B_1) (methylene) and nine other triatomic radicals in cold 3He gas occurs at a slow rate, demonstrating that cryogenic buffer-gas cooling and magnetic trapping of these molecules is feasible with current technology. Our calculations further suggest that it may be possible to create ultracold gases of polyatomic molecules by sympathetic cooling with alkaline-earth atoms in a magnetic trap.Comment: 5 pages, 3 figures, 1 tabl

Evidence for a new light spin-zero boson from cosmological gamma-ray propagation?

Recent findings by Imaging Atmospheric Cherenkov Telescopes indicate a large transparency of the Universe to gamma rays, which can be hardly explained within the current models of extragalactic background light. We show that the observed transparency is naturally produced by an oscillation mechanism -- which can occur inside intergalactic magnetic fields -- whereby a photon can become a new spin-zero boson with mass m << 10^(-10) eV. Because the latter particle travels unimpeded throughout the Universe, photons can reach the observer even if the distance from the source considerably exceeds their mean free path. We compute the expected flux of gamma rays from blazar 3C279 at different energies. Our predictions can be tested in the near future by the gamma-ray telescopes H.E.S.S., MAGIC, CANGAROO and VERITAS. Moreover, our result provides an important observational test for models of dark energy wherein quintessence is coupled to the photon through an effective dimension-five operator.Comment: 4 pages, 1 figur