The Polyakov action on the supertorus

A consistent method for obtaining a well-defined Polyakov action on the supertorus is presented. This method uses the covariantization of derivative operators and enables us to construct a Polyakov action which is globally defined.Comment: 15 pages LaTe

W-algebras from symplectomorphisms

It is shown how $W$-algebras emerge from very peculiar canonical transformations with respect to the canonical symplectic structure on a compact Riemann surface. The action of smooth diffeomorphisms of the cotangent bundle on suitable generating functions is written in the BRS framework while a $W$-symmetry is exhibited. Subsequently, the complex structure of the symmetry spaces is studied and the related BRS properties are discussed. The specific example of the so-called $W_3$-algebra is treated in relation to some other different approaches.Comment: LaTex, 25 pages, no figures, to appear in Journ. Math. Phy

Induced Polyakov supergravity on Riemann surfaces of higher genus

An effective action is obtained for the $N=1$, $2D-$induced supergravity on a compact super Riemann surface (without boundary) $\hat\Sigma$ of genus $g>1$, as the general solution of the corresponding superconformal Ward identity. This is accomplished by defining a new super integration theory on $\hat\Sigma$ which includes a new formulation of the super Stokes theorem and residue calculus in the superfield formalism. Another crucial ingredient is the notion of polydromic fields. The resulting action is shown to be well-defined and free of singularities on \sig. As a by-product, we point out a morphism between the diffeomorphism symmetry and holomorphic properties.Comment: LPTB 93-10, Latex file 20 page

d=2, N=2 Superconformal Symmetries and Models

We discuss the following aspects of two-dimensional N=2 supersymmetric theories defined on compact super Riemann surfaces: parametrization of (2,0) and (2,2) superconformal structures in terms of Beltrami coefficients and formulation of superconformal models on such surfaces (invariant actions, anomalies and compensating actions, Ward identities).Comment: 43 pages, late

Enteroparasitosis in food handlers in the city of Ribeirão Preto - SP, Brazil, 2000

INTRODUÇÃO: A segurança alimentar vêm adquirindo mundialmente uma importância crescente. As doenças transmitidas por alimentos (DTAS) têm impactos na saúde pública e socioeconômicos, acarretando custos hospitalares em tratamentos e internações. As pessoas envolvidas na produção de alimentos podem ser portadoras de enteroparasitos e vir a contaminar os alimentos, provocando surtos de origem alimentar. OBJETIVOS: Investigar a presença de enteroparasitoses em manipuladores de alimentos do município de Ribeirão Preto, SP, propondo medidas que assegurem a qualidade sanitária dos alimentos. MÉTODOS: Entre julho a dezembro de 2000, 429 manipuladores de alimentos (248 mulheres e 181 homens), com idades entre 16 e 77 anos, foram submetidos ao exame coproparasitológico por ocasião da obtenção ou renovação da carteira de saúde. As amostras de fezes foram examinadas pelos métodos de Kato e da sedimentação espontânea. A pesquisa de oocistos de Cryptosporidium spp foi realizada em 7,0% das amostras de fezes diarréicas através da técnica de concentração pelo formol-éter. RESULTADOS: Foram encontradas enteroparasitoses em 33,1% dos manipuladores, incluindo 20,0% de casos de poliparasitismo. Prevalências mais altas de infecções ocorreram entre os indivíduos envolvidos com atividades de manipulação direta dos alimentos (68%). CONCLUSÕES: Considerando os resultados obtidos, são necessários a educação sanitária e o treinamento dos manipuladores bem como a implementação da metodologia da Análise dos Perigos e Pontos Críticos de Controle (APPCC) em todas as etapas da cadeia de produção dos alimentos, para garantir produtos alimentícios seguros aos consumidores.INTRODUCTION: Food safety has become increasingly importance worldwide. Food borne diseases have impacts on public health and socioeconomic factors, accounting for hospital costs in treatments and hospitalizations. People involved in food production can be carriers of enteroparasites and contaminate food, causing food borne diseases OBJECTIVE: The aim of this study was to investigate the presence of enteroparasites in food handlers in Ribeirão Preto, SP, proposing measures to ensure the sanitary quality of food. METHODS: From July to December 2000, 429 food handlers (248 women and 181 men), aged between 16 and 77 years, underwent coproparasitological analysis as a mandatory professional requirement. Fecal samples were analyzed by the Kato's and spontaneous sedimentation methods. Cryptosporidium spp oocysts were investigated in 7.0% of diarrheic fecal samples using the formalin-ether concentration technique. RESULTS: The results showed enteroparasitosis in 33.1% of food handlers, including 20.0% cases of multiple parasitic infections. A higher prevalence of infections (68.0%) was detected among the individuals involved in direct food handling activities. CONCLUSIONS: Considering these results, it is necessary to provide sanitary education and training to food handlers, and to implement the method of Hazard Analysis and Critical Control Points (HACCP) in all stages of the food chain so as to ensure food safety for consumers

Stochastic Background Search Correlating ALLEGRO with LIGO Engineering Data

We describe the role of correlation measurements between the LIGO interferometer in Livingston, LA, and the ALLEGRO resonant bar detector in Baton Rouge, LA, in searches for a stochastic background of gravitational waves. Such measurements provide a valuable complement to correlations between interferometers at the two LIGO sites, since they are sensitive in a different, higher, frequency band. Additionally, the variable orientation of the ALLEGRO detector provides a means to distinguish gravitational wave correlations from correlated environmental noise. We describe the analysis underway to set a limit on the strength of a stochastic background at frequencies near 900 Hz using ALLEGRO data and data from LIGO's E7 Engineering Run.Comment: 8 pages, 2 encapsulated PostScript figures, uses IOP class files, submitted to the proceedings of the 7th Gravitational Wave Data Analysis Workshop (which will be published in Classical and Quantum Gravity

Analysis of a Motocross Knee Brace: From the Real Model to the Numerical Finite Element Model via 3D Scanning and Reverse Engineering

Featured Application: This study outlines a novel procedure for the Finite Element Modelling and Analysis of motocross knee braces under race conditions. The aim is to quantitatively evaluate the effectiveness of such stabilisers in reducing the risk and consequences of musculoskeletal injuries, considering the current lack of industrial standards and dedicated scientific research works. Musculoskeletal injuries often occur when performing motocross; almost half of the overall ligamentous injuries (42%) are knee ligaments injuries. Lesions can be greatly reduced with knee braces. Commercial knee braces are expected to oppose and limit unwanted and potentially harmful movements such as hyperextension and excessive rotation of the knee joint. However, this aspect has not been fully investigated from a biomechanical point of view. This would require proper Finite Element Modelling (FEM) and Analysis (FEA). However, to perform FEA and evaluate the efficacy of the brace simulating sportive conditions, numerical models need to be built. It requires a dedicated setup and several preprocessing steps, for which no industrial standard or widely accepted better practise is available as of today. Firstly, the brace and the lower limb are scanned using a 3D scanner. The geometry is reconstructed using reverse engineering techniques. These allow us to obtain a smooth, reliable 3D model starting from the points cloud acquired during scanning. A lower limb model was created using a mixed approach, combining MRI data and 3D scanning. Finally, a simulation of the impact condition after a jump using the developed model was carried out

Carnot-Caratheodory metric and gauge fluctuation in Noncommutative Geometry

Gauge fields have a natural metric interpretation in terms of horizontal distance. The latest, also called Carnot-Caratheodory or subriemannian distance, is by definition the length of the shortest horizontal path between points, that is to say the shortest path whose tangent vector is everywhere horizontal with respect to the gauge connection. In noncommutative geometry all the metric information is encoded within the Dirac operator D. In the classical case, i.e. commutative, Connes's distance formula allows to extract from D the geodesic distance on a riemannian spin manifold. In the case of a gauge theory with a gauge field A, the geometry of the associated U(n)-vector bundle is described by the covariant Dirac operator D+A. What is the distance encoded within this operator ? It was expected that the noncommutative geometry distance d defined by a covariant Dirac operator was intimately linked to the Carnot-Caratheodory distance dh defined by A. In this paper we precise this link, showing that the equality of d and dh strongly depends on the holonomy of the connection. Quite interestingly we exhibit an elementary example, based on a 2 torus, in which the noncommutative distance has a very simple expression and simultaneously avoids the main drawbacks of the riemannian metric (no discontinuity of the derivative of the distance function at the cut-locus) and of the subriemannian one (memory of the structure of the fiber).Comment: published version with additional figures to make the proof more readable. Typos corrected in this ultimate versio

Supersymmetric structure of the induced W gravities

We derive the supersymmetric structure present in W-gravities which has been already observed in various contexts as Yang-Mills theory, topological field theories, bosonic string and chiral W_{3}-gravity. This derivation which is made in the geometrical framework of Zucchini, necessitates the introduction of an appropriate new basis of variables which replace the canonical fields and their derivatives. This construction is used, in the W_{2}-case, to deduce from the Chern-Simons action the Wess-Zumino-Polyakov action.Comment: 17 pages, Latex. To appear in Class. Quantum. Gravit