On the naturalness of Einstein's equation

We compute all 2-covariant tensors naturally constructed from a semiriemannian metric which are divergence-free and have weight greater than -2. As a consequence, it follows a characterization of the Einstein tensor as the only, up to a constant factor, 2-covariant tensor naturally constructed from a semiriemannian metric which is divergence-free and has weight 0 (i.e., is independent of the unit of scale). Since these two conditions are also satisfied by the energy-momentum tensor of a relativistic space-time, we discuss in detail how these theorems lead to the field equation of General Relativity.Comment: 12 pages, added references, corrected typo

THE EFFECTS OF QUORUM SENSING ANTAGONISTS ON BIOFILM

poster abstractCystic fibrosis (CF) is a recessive genetic disorder that causes the for-mation of thick mucus plugs in the lungs of approximately 30,000 people in the United States and 60,000 individuals world-wide. Pseudomonas aeruginosa, an opportunistic bacterial pathogen, is able to colonize the mu-cus plugs and form antibiotic resistant biofilms. These microbial colonies, known as biofilms, cause serious problems for individuals living with CF. P. aeruginosa biofilms are able to cause chronic infections in the lungs of CF patients leading to increased morbidity and mortality. Using a modified bio-film assay, we tested the effects of modified chemical compounds and amino acids on P. aeruginosa biofilm dispersion. A previous study performed on P. aeruginosa, found that treatment of d- and l- amino acids resulted in biofilm dissemination. Through additional experiments, we will identify modified chemical compounds that induce biofilm dispersion. This research will in-crease our knowledge of P. aeruginosa biofilm dispersion, and allow us to explore new forms of treatment and therapy for CF patients with chronic in-fections that could be life threatening

Developing front-end Web 2.0 technologies to access services, content and things in the future Internet

The future Internet is expected to be composed of a mesh of interoperable web services accessible from all over the web. This approach has not yet caught on since global user?service interaction is still an open issue. This paper states one vision with regard to next-generation front-end Web 2.0 technology that will enable integrated access to services, contents and things in the future Internet. In this paper, we illustrate how front-ends that wrap traditional services and resources can be tailored to the needs of end users, converting end users into prosumers (creators and consumers of service-based applications). To do this, we propose an architecture that end users without programming skills can use to create front-ends, consult catalogues of resources tailored to their needs, easily integrate and coordinate front-ends and create composite applications to orchestrate services in their back-end. The paper includes a case study illustrating that current user-centred web development tools are at a very early stage of evolution. We provide statistical data on how the proposed architecture improves these tools. This paper is based on research conducted by the Service Front End (SFE) Open Alliance initiative

A new genus of microphthalmic Rhytirrhinini from Andean leaf litter (Coleoptera: Curculionidae)

Fil: Anderson, Robert S.. Research Division. Canadian Museum of Nature. Ottawa; CanadaFil: Morrone, Juan José. Laboratorio de Sistemática y Biología Evolutiva (LASBE). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

The Adoption of Food Safety Practices and the Implications of Regulation for Small Scale Farms

In this article we examine the adoption of food safety practices among produce growers in the south and discuss implications of food safety regulations in the U.S. Produce growers have adopted standard food safety practices to varying degrees, but there is still an adoption gap, particularly among small scale operations. Market-driven and regulatory food safety enforcement continues to tighten, and this can further hinder market access for small scale producers

Diseño y construcción de un planta piloto para el tratamiento de agua potable en el Laboratorio de la Universidad Católica de Colombia

Trabajo de Investigación TecnológicaEn el presente trabajo se desarrolla la metodología para el diseño y construcción de una planta de tratamiento de agua potable piloto, en la que se pretende tratar un caudal de 0.1 lps. La planta se compone de una estructura de vertedero triangular, floculador hidráulico horizontal, sedimentador de alta tasa y filtro.INTRODUCCIÓN 1. GENERALIDADES 2. PREPARACIÓN DE LA MUESTRA DE AGUA 3. DISEÑO DEL VERTEDERO 4. DISEÑO DEL FLOCULADOR DE FLUJO HORIZONTAL 5. DISEÑO DEL SEDIMENTADOR DE ALTA TASA 6. DISEÑO DE FILTRO RÁPIDO DE ARENA BIBLIOGRAFÍA ANEXOSPregradoIngeniero Civi

¿Qué nos dicen los índices de confianza?

En este trabajo se cuantifica el contenido informativo de los Índices de Confianza utilizados por el Banco de la República en la elaboración de su Informe sobre Inflación. Se estudian las frecuencias a las que ocurren sus variaciones y se comparan con las frecuencias de medidas similares de los Estados Unidos y de algunos países de Latinoamérica. Se estudia la relación entre los índices de confianza y un conjunto substancialmente grande de variables indicadoras de la actividad económica tanto locales como externas, particularmente con el PIB y sus desagregaciones. Se determina si los índices de confianza o sus preguntas individuales aportan información adicional a la que se tiene en ejercicios en tiempo real sobre la determinación del estado de la economía. Finalmente, se estudia la relación entre los índices de confianza con los de otros países durante la reciente crisis financiera internacional.Índices de confianza, Colombia, análisis espectral, correlación cruzada, análisis de varianza, stepwise. Classification JEL: E20, E23, E24, E31, E40, C10, C14.

Dynamics of the mapping class group action on the variety of PSL(2,C) characters

We study the action of the mapping class group Mod(S) on the boundary dQ of quasifuchsian space Q. Among other results, Mod(S) is shown to be topologically transitive on the subset C in dQ of manifolds without a conformally compact end. We also prove that any open subset of the character variety X(pi_1(S),SL(2,C)) intersecting dQ does not admit a nonconstant Mod(S)-invariant meromorphic function. This is related to a question of Goldman.Comment: This is the version published by Geometry & Topology on 11 July 200