Nullity conditions in paracontact geometry

The paper is a complete study of paracontact metric manifolds for which the Reeb vector field of the underlying contact structure satisfies a nullity condition (the condition \eqref{paranullity} below, for some real numbers $\tilde\kappa$ and $\tilde\mu$). This class of pseudo-Riemannian manifolds, which includes para-Sasakian manifolds, was recently defined in \cite{MOTE}. In this paper we show in fact that there is a kind of duality between those manifolds and contact metric $(\kappa,\mu)$-spaces. In particular, we prove that, under some natural assumption, any such paracontact metric manifold admits a compatible contact metric $(\kappa,\mu)$-structure (eventually Sasakian). Moreover, we prove that the nullity condition is invariant under $\mathcal{D}$-homothetic deformations and determines the whole curvature tensor field completely. Finally non-trivial examples in any dimension are presented and the many differences with the contact metric case, due to the non-positive definiteness of the metric, are discussed.Comment: Different. Geom. Appl. (to appear

Integrable LCK manifolds

We study a natural class of LCK manifolds that we call integrable LCK manifolds: those where the anti-Lee form η corresponds to an integrable distribution. As an application we obtain a characterization of unimodular integrable LCK Lie algebras as Kähler Lie algebras equipped with suitable derivations

On Markov operators preserving polynomials

The paper is concerned with a special class of positive linear operators acting on the space C(K) of all continuous functions defined on a convex compact subset K of R^d, d \geq 1, having non-empty interior. Actually, this class consists of all positive linear operators T on C(K) which leave invariant the polynomials of degree at most 1 and which, in addition, map polynomials into polynomials of the same degree. Among other things, we discuss the existence of such operators in the special case where K is strictly convex by also characterizing them within the class of positive projections. In particular we show that such operators exist if and only if ∂K is an ellipsoid. Furthermore, a characterization of balls of R^d in terms of a special class of them is furnished. Additional results and illustrative examples are presented as well

Comparison Process of Blood Heavy Metals Absorption Linked to Measured Air Quality Data in Areas with High and Low Environmental Impact

Air pollution is a problem shared by the entire world population, and researchers have highlighted its adverse effects on human health in recent years. The object of this paper was the relationship between the pollutants' concentrations measured in the air and the quantity of pollutant itself inhaled by the human body. The area chosen for the study has a high environmental impact given the significant presence on the territory of polluting activities. The Acerra area (HI) has a waste-to-energy plant and numerous industries to which polluting emissions are attributed. This area has always been the subject of study as the numbers of cancer patients are high. A survey on male patients to evaluate the heavy metals concentrations in the blood was conducted in the two areas and then linked to its values aero-dispersed. Using the air quality data measured by the monitoring networks in two zones, one with high environmental impact (HI) and one with low environmental impact (LI), the chronicle daily intake (CDI) of pollutants inhaled by a single person was calculated. The pollutants considered in this study are PM10 and four heavy metals (As, Cd, Ni, Pb) constituting the typical particulates of the areas concerned. The CDI values calculated for the two zones are significantly higher in the HI zone following the seasonal pollution trend

Bounding the B_s -> gamma gamma decay from Higgs mediated FCNC transitions

The Higgs mediated flavor violating bottom-strange quarks transitions induced at the one-loop level by a nondiagonal $Hbs$ coupling are studied within the context of an effective Yukawa sector that comprises $SU_L(2)\times U_Y(1)$-invariant operators of up to dimension-six. The most recent experimental result on $B\to X_s\gamma$ with hard photons is employed to constraint the $Hbs$ vertex, which is used to estimate the branching ratio for the $B_s\to \gamma\gamma$ decay. It is found that the $B_s\to \gamma\gamma$ decay can reach a branching ratio of the order of $4\times 10^{-8}$, which is 2 orders of magnitude more stringent than the current experimental limit.Comment: 9 pages and 5 figure

Análise dos fluxos metabólicos em Saccharomyces cerevisiae a partir de D-xilulose como fonte de carbono utilizando Optflux

A viabilidade econômica da produção de etanol 2G depende da eficiente fermentação da fração hemicelulósica por S. cerevisiae. A xilulose, isômero da xilose e principal componente da hemicelulose do bagaço, pode ser convertida pela levedura em biomassa, etanol, xilitol ou outros metabólitos. A otimização da produção de etanol requer a análise do metabolismo da xilulose. Modelos metabólicos permitem efetuar simulações de sistemas biológicos, viabilizando o estudo in silico das respostas celulares perante perturbações ambientais e genéticas. Uma das técnicas mais usadas para estudos deste tipo é a Análise do Balanço de Fluxos Metabólicos (do inglês, FBA). Neste trabalho, usando o software OptFlux, foi aplicado o método “parcimonious FBA” ao modelo iND750 para estimar os fluxos metabólicos em condições de aerobiose e anaerobiose, utilizando xilulose como fonte de carbono. Os resultados das simulações foram comparados a dados experimentais e o modelo foi ajustado adicionando restrições de expressão em fluxos metabólicos da via pentose fosfato e de formação de biomassa. A produção de etanol só foi observada na condição anaeróbia, com favorecimento da seletividade para baixos fluxos de xilulose

Integrating an autonomous robot on a dance and new technologies festival

This paper presents the results of a project to integrate an autonomous mobile robot into a modern dance performance at a dance and new technologies festival. The main goal is to integrate a simple low cost mobile robot into the dance performance, in order to study the possibilities that this kind of platforms can offer to the artists. First, this work explains the process and design to embed the robotic platform into the choreography theme. Another contribution described in this work is the system architecture proposed and built to make the robot behaviours match the artists requirements: precise, synchronized and robust robot movements. Finally, we discuss the main issues and lessons learned for this kind of robotics and arts applications and summarize the results obtained, including the successful final live performance results