Abordagens estatísticas em testes de resistência de união entre dentina bovina, sistema adesivo e resina composta

Pós-graduação em Odontologia Restauradora - ICT

Behavior of Staphylococcus aureus and autochthone microbiota in fresh sausages added of sodium nitrite and stored under refrigeration

Fresh sausages are cured meat products that may be contaminated with Staphylococcus aureus during the manufacturing procedure, which is frequently related with inadequate handling practices. The use of nitrite in meat products has proven efficacy against Clostridium botulinum, and studies indicate that bactericidal action against S. aureus depends on factors that are intrinsic and extrinsic to the product. The objective of the present study was to evaluate the effect of nitrite concentration, and pH on S. aureus and psychrotrophic autochthone microbiota in fresh sausages stored at different times and temperatures. Fresh sausage were produced at nitrite concentrations 50, 150 and 200ppm and contaminated with S. aureus. The sausages were storage at refrigeration (7 and 12 degrees C) and the quantification of S. aureus and psychrotrophic microorganisms was carried out on days 0, 2, 4, 7, and 10. Results showed that nitrite concentrations and the temperatures used had minimal effect on the multiplication of S. amens and psychrotrophic autochthone microbiota. Final counts depended only on the length of storage: at the end of 10 days, counts were statistically similar in the different groups, showing that temperature and nitrite concentrations used did not control microbial growth effectively. It is suggested that the product should be stored below 7 degrees C or at freezing temperatures for greater microbiological stability.

Root canal filling: fracture strength of fiber-reinforced composite-restored roots and finite element analysis

The aims of this study were to evaluate the effect of root canal filling techniques on root fracture resistance and to analyze, by finite element analysis (FEA), the expansion of the endodontic sealer in two different root canal techniques. Thirty single-rooted human teeth were instrumented with rotary files to a standardized working length of 14 mm. The specimens were embedded in acrylic resin using plastic cylinders as molds, and allocated into 3 groups (n=10): G(lateral) - lateral condensation; G(single-cone) - single cone; G(tagger) - Tagger's hybrid technique. The root canals were prepared to a length of 11 mm with the #3 preparation bur of a tapered glass fiber-reinforced composite post system. All roots received glass fiber posts, which were adhesively cemented and a composite resin core was built. All groups were subjected to a fracture strength test (1 mm/min, 45°). Data were analyzed statistically by one-way ANOVA with a significance level of 5%. FEA was performed using two models: one simulated lateral condensation and Tagger's hybrid technique, and the other one simulated the single-cone technique. The second model was designed with an amount of gutta-percha two times smaller and a sealer layer two times thicker than the first model. The results were analyzed using von Mises stress criteria. One-way ANOVA indicated that the root canal filling technique affected the fracture strength (p=0.004). The G(lateral) and G(tagger) produced similar fracture strength values, while G(single-cone) showed the lowest values. The FEA showed that the single-cone model generated higher stress in the root canal walls. Sealer thickness seems to influence the fracture strength of restored endodontically treated teeth.

Adesivos multi-uso-avaliação da resistência adesiva a dentina frente a teste de cisalhamento, estereomicroscopia e microscopia eletrônica de varredura

Recent bonding systems have been advocated as multi-purpose bonding agents. The aim of this study was to determine if some of these bonding systems could be associated to composite resins from different manufacturers. This investigation was conducted to test lhe shear bond strength of three bonding systems: Scotchbond Multi-Purpose (3M Dental Products), Optibond Light Cure (Kerr) and Optibond Dual Cure (Kerr), when each of them was associated to lhe composite resins: Z1 00 (3M Dental Products), Prisma - APH (Dentsply) and Herculite XRV (Kerr). Seventy-two flat dentin bonding sites were prepared to 600 grit on human premolars mounted using acrilic resins. The teeth were assigned at random to 9 groups of 8 samples each. A split die with a 3mm diameter was placed over lhe surface of lhe dentin treated with one of lhe adhesive systems, and lhe selected composite resin was inserted and light cured. The split mold was removed and all samples were termocycled and stored in 37ºC water for 24 hours before testing. Shear bond strength was determined using an lnstron Universal testing machine. Some failures were examined under lhe S.E.M. Data was analysed by one-way analysis of variance, that demonstrated a significant difference (p<0,05) in the mean shear bond strength among Optibond Light Cure (15,446 MPa), Scotchbond Multi-Purpose (13,339 MPa) and Optibond Dual Cure (10,019 MPa). These values did not depend on the composite resin used. The association between bonding system/composite resin was statistycally significant (p<0,05) and the best results were obtained when the composite resins Z100 and Herculite were used with the adhesive system Optibond Light Cure, and when the composite resin APH was used with the adhesive system Scotchbond Multi-Purpose

Análise da influência do agente umectante na estabilidade reológica e avaliação de cristais líquidos em formulações cosméticas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo de dormentes de aço sob solicitações verticais, longitudinais e transversais em via permanente ferroviária

This article presents the results of research conducted on full-scale models, studying the behavior of steel sleepers under the action of static loads, in vertical, longitudinal and transverse directions. For the research models were run with rails TR-68, fixed with elastic system on seven sleepers each type, separately, embedded in standard ballast with 35 cm height and on the basis of compacted soil with 30 cm thick. For the load tests were constructed using reaction systems of vertical and horizontal forces with the objective of applying the requests. The system of readings and data acquisition was fully computerized, obtaining in real time the values of forces and displacements. The results were compared with those installed in the same way with sleepers of wood, mono-block and bi-block prestressed concrete. The analyzed results provided unprecedented parameters in Brazil and of great importance for the design of modern railway permanent way, using steel sleepers.

Desenvolvimento de um embutido cárneo fermentado, com teores reduzidos de gordura e sais de cura, através da utilização de culturas probióticas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação do desempenho ambiental e racionalização do consumo de água no segmento industrial de produção de bebidas

A região Amazônica, detentora de grande potencial hídrico, tem atraído indústrias que promovem uso intensivo de água, por isso, existe uma emergência por instrumentos que administrem essa tendência. Neste trabalho foi diagnosticado o nível de racionalização do uso da água pelo setor industrial de produção de bebidas no estado do Pará, assim como as causas do comportamento do setor. As variáveis dependentes (de comportamento) foram classificadas de acordo com quatro dimensões (gestão ambiental, manejo da água, manejo dos efluentes e medidas avançadas de racionalização) que compõe o nível de racionalização da gestão industrial hídrica. As variáveis independentes foram associadas ao: porte, ramo, tipo de embalagem utilizada, disponibilidade hídrica e valor econômico da água. Os dados levantados mostraram que a produção de bebidas tem uma grande pegada hídrica operacional total (acima de) 15.250 m³/dia, com as pequenas empresas apresentando o maior consumo relativo por unidade produzida (maior que 7 L de água/L de bebida). O setor como um todo apresenta baixo nível de racionalização do uso da água, a dimensão mais eficiente é a de gerenciamento da água; entretanto algumas medidas avançadas podem ser visualizadas, especialmente a recirculação da água em torres de resfriamento. A análise das variáveis de estudo demonstra que o nível de racionalização é dependente diretamente do ramo e do porte da empresa. Conclui-se que o consumo tende ao desperdício; em resposta a este quadro, devem ser priorizadas políticas públicas voltadas para internalização dos custos ambientais embutidos no processo.

Efficient Forest Data Structure for Evolutionary Algorithms Applied to Network Design

The design of a network is a solution to several engineering and science problems. Several network design problems are known to be NP-hard, and population-based metaheuristics like evolutionary algorithms (EAs) have been largely investigated for such problems. Such optimization methods simultaneously generate a large number of potential solutions to investigate the search space in breadth and, consequently, to avoid local optima. Obtaining a potential solution usually involves the construction and maintenance of several spanning trees, or more generally, spanning forests. To efficiently explore the search space, special data structures have been developed to provide operations that manipulate a set of spanning trees (population). For a tree with n nodes, the most efficient data structures available in the literature require time O(n) to generate a new spanning tree that modifies an existing one and to store the new solution. We propose a new data structure, called node-depth-degree representation (NDDR), and we demonstrate that using this encoding, generating a new spanning forest requires average time O(root n). Experiments with an EA based on NDDR applied to large-scale instances of the degree-constrained minimum spanning tree problem have shown that the implementation adds small constants and lower order terms to the theoretical bound.

Investigating Smart Sampling as a population initialization method for Differential Evolution in continuous problems

Recently, researches have shown that the performance of metaheuristics can be affected by population initialization. Opposition-based Differential Evolution (ODE), Quasi-Oppositional Differential Evolution (QODE), and Uniform-Quasi-Opposition Differential Evolution (UQODE) are three state-of-the-art methods that improve the performance of the Differential Evolution algorithm based on population initialization and different search strategies. In a different approach to achieve similar results, this paper presents a technique to discover promising regions in a continuous search-space of an optimization problem. Using machine-learning techniques, the algorithm named Smart Sampling (SS) finds regions with high possibility of containing a global optimum. Next, a metaheuristic can be initialized inside each region to find that optimum. SS and DE were combined (originating the SSDE algorithm) to evaluate our approach, and experiments were conducted in the same set of benchmark functions used by ODE, QODE and UQODE authors. Results have shown that the total number of function evaluations required by DE to reach the global optimum can be significantly reduced and that the success rate improves if SS is employed first. Such results are also in consonance with results from the literature, stating the importance of an adequate starting population. Moreover, SS presents better efficacy to find initial populations of superior quality when compared to the other three algorithms that employ oppositional learning. Finally and most important, the SS performance in finding promising regions is independent of the employed metaheuristic with which SS is combined, making SS suitable to improve the performance of a large variety of optimization techniques. (C) 2012 Elsevier Inc. All rights reserved.

Simple heuristics for the assembly line worker assignment and balancing problem

We propose simple heuristics for the assembly line worker assignment and balancing problem. This problem typically occurs in assembly lines in sheltered work centers for the disabled. Different from the well-known simple assembly line balancing problem, the task execution times vary according to the assigned worker. We develop a constructive heuristic framework based on task and worker priority rules defining the order in which the tasks and workers should be assigned to the workstations. We present a number of such rules and compare their performance across three possible uses: as a stand-alone method, as an initial solution generator for meta-heuristics, and as a decoder for a hybrid genetic algorithm. Our results show that the heuristics are fast, they obtain good results as a stand-alone method and are efficient when used as a initial solution generator or as a solution decoder within more elaborate approaches.

LALP: a language to program custom FPGA-based acceleration engines

Field-Programmable Gate Arrays (FPGAs) are becoming increasingly important in embedded and high-performance computing systems. They allow performance levels close to the ones obtained with Application-Specific Integrated Circuits, while still keeping design and implementation flexibility. However, to efficiently program FPGAs, one needs the expertise of hardware developers in order to master hardware description languages (HDLs) such as VHDL or Verilog. Attempts to furnish a high-level compilation flow (e.g., from C programs) still have to address open issues before broader efficient results can be obtained. Bearing in mind an FPGA available resources, it has been developed LALP (Language for Aggressive Loop Pipelining), a novel language to program FPGA-based accelerators, and its compilation framework, including mapping capabilities. The main ideas behind LALP are to provide a higher abstraction level than HDLs, to exploit the intrinsic parallelism of hardware resources, and to allow the programmer to control execution stages whenever the compiler techniques are unable to generate efficient implementations. Those features are particularly useful to implement loop pipelining, a well regarded technique used to accelerate computations in several application domains. This paper describes LALP, and shows how it can be used to achieve high-performance computing solutions.

Algoritmos evolutivos e modelo HP para predição de estruturas de proteínas

Predição de estruturas de proteínas (PSP) é um problema computacionalmente complexo. Modelos simplificados da molécula proteica (como o Modelo HP) e o uso de Algoritmos Evolutivos (AEs) estão entre as principais técnicas investigadas para PSP. Entretanto, a avaliação de uma estrutura representada pelo Modelo HP considera apenas o número de contatos hidrofóbicos, não possibilitando distinguir entre estruturas com o mesmo número de contatos hidrofóbicos. Neste trabalho, é apresentada uma nova formulação multiobjetivo para PSP em Modelo HP. Duas métricas são avaliadas: o número de contatos hidrofóbicos e a distância entre os aminoácidos hidrofóbicos, as quais são tratados pelo AE Multiobjetivo em Tabelas (AEMT). O algoritmo mostrou-se rápido e robusto.

Programmable logic design of a compact Genetic Algorithm for phasor estimation in real-time

The main objective of this work is to present an efficient method for phasor estimation based on a compact Genetic Algorithm (cGA) implemented in Field Programmable Gate Array (FPGA). To validate the proposed method, an Electrical Power System (EPS) simulated by the Alternative Transients Program (ATP) provides data to be used by the cGA. This data is as close as possible to the actual data provided by the EPS. Real life situations such as islanding, sudden load increase and permanent faults were considered. The implementation aims to take advantage of the inherent parallelism in Genetic Algorithms in a compact and optimized way, making them an attractive option for practical applications in real-time estimations concerning Phasor Measurement Units (PMUs).

Ferias francas en el ámbito rural : Una mirada desde el enfoque de género

El presente resumen se propone describir las primeras reflexiones que surgen a partir de la realización de dos trabajos de campo en la localidad rural de El Espinillo, provincia de Formosa, donde se observó e indagó acerca del funcionamiento de la feria franca que allí se encuentra. Se plantea un abordaje desde la psicología comunitaria con énfasis en la perspectiva de género, con el objetivo de determinar si la participación de las mujeres feriantes en este tipo de actividades produce modificaciones o no en sus roles sociales y familiares tradicionales. Por otra parte se indaga el modo de funcionamiento de la feria y los factores que favorecen y/o perjudican su desarrollo y potencialidad. En ambas salidas a terreno se han realizado un total de veinte entrevistas semi-dirigidas a hombres y mujeres feriantes de la localidad. A su vez se han desarrollado observaciones participantes y no participantes, al igual que la confección de un diario de campo. Las Ferias Francas son establecimientos donde se comercializan principalmente frutas y verduras, como así también productos mas elaborados tales como quesos, dulces y embutidos, entre otros (Petit, Petit, Rotman & Aradas, 2009). Participan en ellas hombres y mujeres campesinos. Las ferias, generalmente, tienen días y horarios fijos de funcionamiento. Los precios de los productos suelen ser menores al de los productos de comercios o mercados de la misma región. En el caso concreto de la feria franca de El Espinillo, se comercializan desde huevos, leche, quesos, embutidos, verduras y frutas, mermeladas y miel hasta pollos y ropa. La feria funciona los días miércoles y sábados de 8 hs. a 13 hs, y eventualmente los días lunes en el mismo horario. Quienes participan son principalmente mujeres campesinas. No obstante, también hay algunos hombres que trabajan ya sea en forma directa, es decir, vendiendo en la misma feria, o de manera indirecta, colaborando en la producción de las mercaderías en la chacra. (Landini, 2010). El 'trabajo de chacra' es entendido como el trabajo en cultivos que ocupan mayor extensión de tierra (cultivo de algodón, entre otros); o bien como cría de ganado bovino y/u ovino. A su vez, dentro de la chacra, se distingue el espacio destinado a la huerta, el cual ocupa una extensión de tierra menor. Allí se producen frutas, hortalizas y se crían distintos tipos de animales tales como chanchos, gallinas y diversas aves de corral. A su vez, se puede mencionar que el trabajo de la chacra, generalmente, se asocia a roles masculinos, y el de la huerta a roles femeninos (Landini, 2010). Esta distinción entre trabajo masculino y femenino introduce una distinción cualitativa sustancial en lo referido a la cuestión de género En el caso de El Espinillo, se pudo apreciar que la mujer, además de trabajar como ama de casa (función reproductiva) (Petit et al., 2009), realiza trabajos en la huerta, sembrando verduras y hortalizas, como así también en la cría de diversos animales tales como chanchos y gallinas, entre otros (función productiva). Estos productos luego son comercializados en la feria, los cuales tienen un valor económico y de subsistencia en la familia de vital importancia. Sin embargo, parecería ser que estas actividades productivas son tomadas socialmente, tanto por hombres como mujeres, como una extensión del trabajo de ama de casa, lo cual da como resultado que el valor del trabajo productivo se entrecruce con el valor del trabajo reproductivo, lo que da lugar a que el primero quede invisibilizado como 'trabajo' en si mismo, socialmente aceptado y valorado (Petit, et al., 2009). Es decir, la mujer, cuando produce, ayuda. En cambio, el hombre, cuando produce, trabaja. A partir de lo mencionado se podría pensar en cierta naturalización del rol secundario y pasivo de la mujer en relación al hombre. Es por esto que se vuelve de interés indagar qué impacto subjetivo produce el trabajo en la feria, la cual podría comenzar a pensarse como un espacio de encuentro e interacción y no solo como establecimiento de venta de productos. Esto podría dar lugar a hacer visible socialmente la distinción entre la función reproductiva y productiva de la mujer, valorando su trabajo ya no solo como extensión de los quehaceres hogareños. Esta situación daria como resultado un impacto subjetivo significativo en las mujeres feriantes y un cambio respecto a cómo se considera a la mujer en tanto trabajadora, ahora, socialmente reconocida como tal