Cosmological test on viscous bulk models using Hubble Parameter measurements and type Ia Supernovae data

From a phenomenological point of view, we analyze the dynamics of the Universe at late times by introducing a polynomial and hyperbolic bulk viscosity into the Einstein field equations respectively. We constrain their free parameters using the observational Hubble parameter data and the Type Ia Supernovae dataset to reconstruct the deceleration $q$ and the jerk $j$ parameters within the redshift region $0<z<2.5$. At current epochs, we obtain $q_0 = -0.680^{+0.085}_{-0.102}$ and $j_0 = 2.782^{+1.198}_{-0.741}$ for the polynomial model and $q_0 = -0.539^{+0.040}_{-0.038}$ ($-0.594^{+0.056}_{-0.056}$) and $j_0 = 0.297^{+0.051}_{-0.050}$ ($1.124^{+0.196}_{-0.178}$) for the tanh (cosh) model. Furthermore, we explore the statefinder diagnostic that gives us evident differences with respect to the concordance model (LCDM). According to our results this kind of models is not supported by the data over LCDM.Comment: Accepted for publication in EPJ

Infinite Dimensional Forward-Backward Stochastic Differential Equations and the KPZ Equation

Kardar-Parisi-Zhang (KPZ) equation is a quasilinear stochastic partial differential equation(SPDE) driven by a space-time white noise. In recent years there have been several works directed towards giving a rigorous meaning to a solution of this equation. Bertini, Cancrini and Giacomin have proposed a notion of a solution through a limiting procedure and a certain renormalization of the nonlinearity. In this work we study connections between the KPZ equation and certain infinite dimensional forward-backward stochastic differential equations. Forward-backward equations with a finite dimensional noise have been studied extensively, mainly motivated by problems in mathematical finance. Equations considered here differ from the classical works in that, in addition to having an infinite dimensional driving noise, the associated SPDE involves a non-Lipschitz (namely a quadratic) function of the gradient. Existence and uniqueness of solutions of such infinite dimensional forward-backward equations is established and the terminal values of the solutions are then used to give a new probabilistic representation for the solution of the KPZ equation

Vibrio elicits targeted transcriptional responses from copepod hosts

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Federation of European Microbiological Societies for personal use, not for redistribution. The definitive version was published in FEMS Microbiology Ecology 92 (2016): fiw072, doi:10.1093/femsec/fiw072.Copepods are abundant crustaceans that harbor diverse bacterial communities, yet the nature of their interactions with microbiota are poorly understood . Here, we report that Vibrio elicits targeted transcriptional responses in the estuarine copepod Eurytemora affinis. We pre-treated E. affinis with an antibiotic-cocktail and exposed them to either a zooplankton specialist (Vibrio sp. F10 9ZB36) or a free-living species (V. ordalii 12B09) for 24 hours. We then identified via RNA-Seq a total of 78 genes that were differentially expressed following Vibrio exposure, including homologs of C-type lectins, chitin-binding proteins and saposins. The response differed between the two Vibrio treatments, with the greatest changes elicited upon inoculation with V. sp. F10. We suggest that these differentially regulated genes play important roles in cuticle integrity, the innate immune response, and general stress responses, and that their expression may enable E. affinis to recognize and regulate symbiotic vibrios. We further report that V. sp. F10 culturability is specifically altered upon colonization of E. affinis. These findings suggest that rather than acting as passive environmental vectors, copepods discriminately interact with vibrios, which may ultimately impact the abundance and activity of copepod-associated bacteria.2017-04-0