Scaling limits of a tagged particle in the exclusion process with variable diffusion coefficient

We prove a law of large numbers and a central limit theorem for a tagged particle in a symmetric simple exclusion process in the one-dimensional lattice with variable diffusion coefficient. The scaling limits are obtained from a similar result for the current through -1/2 for a zero-range process with bond disorder. For the CLT, we prove convergence to a fractional Brownian motion of Hurst exponent 1/4.Comment: 9 page

Current state of knowledge of freshwater malacostracans of Chile

Indexación: ScieloLa fauna de crustáceos malacostráceos limnéticos, en el territorio de Chile continental, está compuesta por seis especies de camarones, i.e., cinco parastácidos de los géneros Parastacus, Samastacus y Virilastacus y un palemónido del género Cryphiops, 18 especies de anomuros del género Aegla, siete especies de anfípodos gamarídeos del género Hyallela y una especie de isópodo aselotano del género Heterias. La distribución conjunta abarca desde Arica a Punta Arenas, pero la mayor parte de las especies tiene rango geográfico restringido. La mayor densidad de taxa ocurre entre las regiones VIII y X, donde el número de taxa por Región varía entre 11 y 15, siendo la X Región la que tiene el número mayor. Índices derivados de un estudio sobre relaciones filogenéticas de las especies chilenas de Aegla, combinados con criterios propuestos por IUCN (2001), calificó a A. concepcionensis y A. expansa como especies Extintas y a A. papudo, A. l. laevis y A. spectabilis como Críticamente Amenazadas. Además, asignó máxima prioridad de conservación a la zona comprendida entre las cuencas del río Tucapel y del río Toltén. El estado de conservación de las especies de Parastacidae fue establecido por Bahamonde et al. (1998) y complementado por Rudolph & Crandall (2005). El estado de conservación de las especies de Hyalella y del isópodo Heterias exul no ha sido determinado. Se percibe que las amenazas a la conservación de las especies de malacostráceos limnéticos en Chile derivan principalmente de perturbaciones antropogénicas de la integridad y salud ambiental de las cuencas hidrográficas, particularmente entre las Regiones IV a VIII. Palabras claves: Malacostráceos, diversidad, conservación, Amphipoda, Isopoda, Decapoda, Chile, limnología. -------------------------------------------------------------------------------- ABSTRACT The continental Chilean limnetic malacostracan fauna is currently composed of six species of crayfish / shrimp, i.e., five parastacids in the genus Parastacus, Samastacus and Virilastacus, and one palaemonid in the genus Cryphiops, eighteen species of anomuran crabs in the genus Aegla, seven species of gammaridean amphipods in the genus Hyalella, and one species of asellotan isopod in the genus Heterias. The distribution of the set of thirty one species of malacostracans spans from Arica in the north to Magallanes in the far south. However, most species have a restricted geographic range, comprising one or a few hydrographical contiguous basins along the latitudinal gradient. The largest concentration of malacostracan species is found between the VIII and X Administrative Regions of Chile; being the X the largest with fifteen taxa. Indices derived from a phylogenetic study concerning the relationship of the Chilean species of Aegla, and considering the conservation criteria proposed by UICN (2001), qualified A. concepcionensis and A. expansa as Extinct in the Wild, and A. papudo, A. l. laevis and A. spectabilis as Critically Endangered species. Furthermore, it assigned maximum conservation priority to the coastal area between the Tucapel and the Tolten rivers. The conservation status of the species of Parastacidae was established by Bahamonde et al. (1998), and supplemented by Rudolph & Crandall (2005). The conservation status of Hyalella and Heterias species has not yet been determined. It is apparent that threats to the conservation of a large number of limnetic malacostracan species in Chile arise from non quantified anthropogenic perturbations of the limnetic environment, particularly between the IV and VIII Regions. Keywords: Malacostracans, diversity, conservation, Amphipoda, Isopoda, Decapoda, Chile, limnology

Long time, large scale limit of the Wigner transform for a system of linear oscillators in one dimension

We consider the long time, large scale behavior of the Wigner transform W_\eps(t,x,k) of the wave function corresponding to a discrete wave equation on a 1-d integer lattice, with a weak multiplicative noise. This model has been introduced in Basile, Bernardin, and Olla to describe a system of interacting linear oscillators with a weak noise that conserves locally the kinetic energy and the momentum. The kinetic limit for the Wigner transform has been shown in Basile, Olla, and Spohn. In the present paper we prove that in the unpinned case there exists $\gamma_0>0$ such that for any $\gamma\in(0,\gamma_0]$ the weak limit of W_\eps(t/\eps^{3/2\gamma},x/\eps^{\gamma},k), as \eps\ll1, satisfies a one dimensional fractional heat equation $\partial_t W(t,x)=-\hat c(-\partial_x^2)^{3/4}W(t,x)$ with $\hat c>0$. In the pinned case an analogous result can be claimed for W_\eps(t/\eps^{2\gamma},x/\eps^{\gamma},k) but the limit satisfies then the usual heat equation

Protective Yeasts Control V. anguillarum Pathogenicity and Modulate the Innate Immune Response of Challenged Zebrafish (Danio rerio) Larvae

Indexación: Web of ScienceWe investigated mechanisms involved in the protection of zebrafish (Danio rerio) larvae by two probiotic candidate yeasts, Debaryornyces hansenii 97 (Dh97) and Yarrowia Iypolitica 242 (YI242), against a Vibrio anguillarum challenge. We determined the effect of different yeast concentrations (10(4)-10(7) CFU/mL) to: (i) protect larvae from the challenge, (ii) reduce the in vivo pathogen concentration and (iii) modulate the innate immune response of the host. To evaluate the role of zebrafish microbiota in protection, the experiments were performed in conventionally raised and germ free larvae. In vitro co-aggregation assays were performed to determine a direct yeast-pathogen interaction. Results showed that both yeasts significantly increased the survival rate of conventionally raised larvae challenged with V. anguillarum. The concentration of yeasts in larvae tended to increase with yeast inoculum, which was more pronounced for Dh97. Better protection was observed with Dh97 at a concentration of 106 CFU/mL compared to 104 CFU/mL. In germ-free conditions V anguillarum reached higher concentrations in larvae and provoked significantly more mortality than in conventional conditions, revealing the protective role of the host microbiota. Interestingly, yeasts were equally (Dh97) or more effective (YI242) in protecting germ-free than conventionally-raised larvae, showing that protection can be exerted only by yeasts and is not necessarily related to modulation of the host microbiota. Although none of the yeasts co aggregated with V anguillarum, they were able to reduce its proliferation in conventionally raised larvae, reduce initial pathogen concentration in germ-free larvae and prevent the upregulation of key components of the inflammatory/anti-inflammatory response (il1b, tnfa, c3, mpx, and il10, respectively). These results show that protection by yeasts of zebrafish larvae challenged with V anguillarum relates to an in vivo anti-pathogen effect, the modulation of the innate immune system, and suggests that yeasts avoid the host-pathogen interaction through mechanisms independent of co-aggregation. This study shows, for the first time, the protective role of zebrafish microbiota against V. anguillarum infection, and reveals mechanisms involved in protection by two non-Saccharomyces yeasts against this pathogen.http://journal.frontiersin.org/article/10.3389/fcimb.2016.00127/ful

Crossover to the KPZ equation

We characterize the crossover regime to the KPZ equation for a class of one-dimensional weakly asymmetric exclusion processes. The crossover depends on the strength asymmetry $an^{2-\gamma}$ ($a,\gamma>0$) and it occurs at $\gamma=1/2$. We show that the density field is a solution of an Ornstein-Uhlenbeck equation if $\gamma\in(1/2,1]$, while for $\gamma=1/2$ it is an energy solution of the KPZ equation. The corresponding crossover for the current of particles is readily obtained.Comment: Published by Annales Henri Poincare Volume 13, Number 4 (2012), 813-82