ϕ\phi meson transparency in nuclei from ϕN\phi N resonant interactions

We investigate the $\phi$ meson nuclear transparency using some recent theoretical developments on the $\phi$ in medium self-energy. The inclusion of direct resonant $\phi N$-scattering and the kaon decay mechanisms leads to a $\phi$ width much larger than in most previous theoretical approaches. The model has been confronted with photoproduction data from CLAS and LEPS and the recent proton induced $\phi$ production from COSY finding an overall good agreement. The results support the need of a quite large direct $\phi N$-scattering contribution to the self-energy

Global well-posedness for the critical 2D dissipative quasi-geostrophic equation

We give an elementary proof of the global well-posedness for the critical 2D dissipative quasi-geostrophic equation. The argument is based on a non-local maximum principle involving appropriate moduli of continuity.Comment: 7 page

Direct observation of melting in a 2-D superconducting vortex lattice

Topological defects such as dislocations and disclinations are predicted to determine the twodimensional (2-D) melting transition. In 2-D superconducting vortex lattices, macroscopic measurements evidence melting close to the transition to the normal state. However, the direct observation at the scale of individual vortices of the melting sequence has never been performed. Here we provide step by step imaging through scanning tunneling spectroscopy of a 2-D system of vortices up to the melting transition in a focused-ion-beam nanodeposited W-based superconducting thin film. We show directly the transition into an isotropic liquid below the superconducting critical temperature. Before that, we find a hexatic phase, characterized by the appearance of free dislocations, and a smectic-like phase, possibly originated through partial disclination unbinding. These results represent a significant step in the understanding of melting of 2-D systems, with impact across several research fields, such as liquid crystal molecules, or lipids in membranes.Comment: Submitted to Nature Physic

Influence of type of uniform and days of usage in microbiological contamination of nurses uniform in a university hospital

Presentación de un póster presentado al International Conference on Prevention & Infection Control (ICPIC 2011) Geneva, Switzerland. 29 June – 2 July 2011Nurse uniforms can act as a reservoir of infections, with the areas around the pockets, cuffs and aprons the most contaminated. The aim of this study is compare the contamination of Standard nurse’s uniform consisted of a dress, pinafore apron with the “scrub dress” type of uniform, as well as to measure the influence of the number of shifts as uniform was used in its contamination

Comparative analysis on strains in asphalt pavement design using linear elastic and viscoelastic theories

In Colombia it is common to design pavements using the AASHTO 93 method and to complement it with an elastic analysis of the deformations that cause fatigue and rutting; this has repercussions on the behavior of the structure since it does not take into account the viscoelastic behavior of the asphalt mixtures, In this research, a comparison of three structures at different velocity ranges is made to compare the variation in fatigue and rutting concerning the traditional method of analysis in Colombia and to analyze the differences that may occur in linear elastic analysis and viscoelastic analysis of rutting and fatigue

Universality of Probability Distributions Among Two-Dimensional Turbulent Flows

We study statistical properties of two-dimensional turbulent flows. Three systems are considered: the Navier-Stokes equation, surface quasi-geostrophic flow, and a model equation for thermal convection in the Earth's mantle. Direct numerical simulations are used to determine 1-point fluctuation properties. Comparative study shows universality of probability density functions (PDFs) across different types of flow. Especially for the derivatives of the ``advected'' quantity, the shapes of the PDFs are the same for the three flows, once normalized by the average size of fluctuations. Theoretical models for the shape of PDFs are briefly discussed.Comment: 5 pages, 7 figure

White Blood, Black Gold: The Commodification of Wild Rubber in the Bolivian Amazon, 1870-1920

The Bolivian rubber boom thrived during the 1880 and 1920 decades throughout the Amazonian fluvial network (Madre de Dios, Beni, Purús, Madeira and Beni rivers). The economic potential of rubber quickly became a decisive phenomenon in the social history of Eastern Bolivia, linked with the definitive ocupation of marginal territories, new interethnic relations, national and international migration, taxation, property entitlement, the foundation of cities, the rise of nationalism, the struggle to settle republican frontiers and a novel regional opening to global economy. The boom also encouraged substantial developments in cartography, hidrography, botanics and ethnology. Our goal is to describe the singularities of the rubber-tapping industry in Bolivia and to analyse the representations of “nature” held by rubber tappers of the period: there was indeed a modernist discourse based on the usual ideas of "progress" and "civilization" of the industry opposed to the "wildness", "savagery" and "barbarism" massively attributed to Amazonia, and also a generalized notion of the jungle as a "desert land" open to opportunities for the self-made man. In retrospect, these discourses can certainly reveal a lack of “ecological awareness”. However, a closer analysis of historical sources also shows the existence of voices that were more nuanced and reflexive, and in some cases even dared to point out the limits of extractivism –not only in "ecological" terms but also in reference to the life of the indigenous and creole populations involved in the rubber boom

Resonance-free Region in scattering by a strictly convex obstacle

We prove the existence of a resonance free region in scattering by a strictly convex obstacle with the Robin boundary condition. More precisely, we show that the scattering resonances lie below a cubic curve which is the same as in the case of the Neumann boundary condition. This generalizes earlier results on cubic poles free regions obtained for the Dirichlet boundary condition.Comment: 29 pages, 2 figure