Hydrogen oxidation on ordered intermetallic phases of platinum and tin - A combined experimental and theoretical study

Hydrogen oxidation on the surfaces of the intermetallic compounds Pt 3Sn, PtSn and PtSn2 has been studied by the rotating disc electrode technique. Pt3Sn and PtSn were found to be good catalysts, about as good as Pt, while PtSn2 was inactive over the investigated range of potentials. Underpotential deposition of hydrogen is observed only on Pt3Sn. These results are explained by theoretical calculations based on a theory developed within our own group, and by density functional theory. © 2012 Elsevier B.V.

Risk management in software projects through Knowledge Management techniques: Cases in Brazilian Incubated Technology-Based Firms

In businesses such as the software industry, which uses knowledge as a resource, activities are knowledge intensive, requiring constant adoption of new technologies and practices. Another feature of this environment is that the industry is particularly susceptible to failure; with this in mind, the objective of this research is to analyze the integration of Knowledge Management techniques into the activity of risk management as it applies to software development projects of micro and small Brazilian incubated technology-based firms. Research methods chosen were the Multiple Case Study. The main risk factor for managers and developers is that scope or goals are often unclear or misinterpreted. For risk management, firms have found that Knowledge Management techniques of conversion combination would be the most applicable for use; however, those most commonly used refer to the conversion mode as internalization.. © 2013 Elsevier Ltd. APM and IPMA.

Two matrix-based lattice construction techniques

Let m and n be integers greater than 1. Given lattices A and B of dimensions m and n, respectively, a technique for constructing a lattice from them of dimension m+n-1 is introduced. Furthermore, if A and B possess bases satisfying certain conditions, then a second technique yields a lattice of dimension m+n-2. The relevant parameters of the new lattices are given in terms of the respective parameters of A,B, and a lattice C isometric to a sublattice of A and B. Denser sphere packings than previously known ones in dimensions 52, 68, 84, 248, 520, and 4098 are obtained. © 2012 Elsevier Inc. All rights reserved.

Composition and interrelationships of a large Neotropical freshwater fish group, the subfamily Cheirodontinae (Characiformes: Characidae): A case study based on mitochondrial and nuclear DNA sequences

•Relationships of Cheirodontinae based on a broad taxonomic sample.•Results reject the monophyly of Cheirodontinae as previously conceived.•Exclusion of Amazonspinther and Spintherobolus from the subfamily Cheirodontinae.•The removal of Leptagoniates pi of the genus Leptagoniates and inclusion in Cheirodontinae.•Division of Cheirodontinae in three newly defined monophyletic tribes. Characidae is the most species-rich family of freshwater fishes in the order Characiformes, with more than 1000 valid species that correspond to approximately 55% of the order. Few hypotheses about the composition and internal relationships within this family are available and most fail to reach an agreement. Among Characidae, Cheirodontinae is an emblematic group that includes 18 genera (1 fossil) and approximately 60 described species distributed throughout the Neotropical region. The taxonomic and systematic history of Cheirodontinae is complex, and only two hypotheses about the internal relationships in this subfamily have been reported to date. In the present study, we test the composition and relationships of fishes assigned to Cheirodontinae based on a broad taxonomic sample that also includes some characid incertae sedis taxa that were previously considered to be part of Cheirodontinae. We present phylogenetic analyses of a large molecular dataset of mitochondrial and nuclear DNA sequences. Our results reject the monophyly of Cheirodontinae as previously conceived, as well as the tribes Cheirodontini and Compsurini, and the genera Cheirodon, Compsura, Leptagoniates, Macropsobrycon, Odontostilbe, and Serrapinnus. On the basis of these results we propose: (1) the exclusion of Amazonspinther and Spintherobolus from the subfamily Cheirodontinae since they are the sister-group of all remaining Characidae; (2) the removal of Macropsobrycon xinguensis of the genus Macropsobrycon; (3) the removal of Leptagoniates pi of the genus Leptagoniates; (4) the inclusion of Leptagoniates pi in the subfamily Cheirodontinae; (5) the removal of Cheirodon stenodon of the genus Cheirodon and its inclusion in the subfamily Cheirodontinae under a new genus name; (6) the need to revise the polyphyletic genera Compsura, Odontostilbe, and Serrapinnus; and (7) the division of Cheirodontinae in three newly defined monophyletic tribes: Cheirodontini, Compsurini, and Pseudocheirodontini. Our results suggest that our knowledge about the largest Neotropical fish family, Characidae, still is incipient. © 2013 Elsevier Inc..

Analyzing the effect of homogeneous frustration in protein folding

The energy landscape theory has been an invaluable theoretical framework in the understanding of biological processes such as protein folding, oligomerization, and functional transitions. According to the theory, the energy landscape of protein folding is funneled toward the native state, a conformational state that is consistent with the principle of minimal frustration. It has been accepted that real proteins are selected through natural evolution, satisfying the minimum frustration criterion. However, there is evidence that a low degree of frustration accelerates folding. We examined the interplay between topological and energetic protein frustration. We employed a Cα structure-based model for simulations with a controlled nonspecific energetic frustration added to the potential energy function. Thermodynamics and kinetics of a group of 19 proteins are completely characterized as a function of increasing level of energetic frustration. We observed two well-separated groups of proteins: one group where a little frustration enhances folding rates to an optimal value and another where any energetic frustration slows down folding. Protein energetic frustration regimes and their mechanisms are explained by the role of non-native contact interactions in different folding scenarios. These findings strongly correlate with the protein free-energy folding barrier and the absolute contact order parameters. These computational results are corroborated by principal component analysis and partial least square techniques. One simple theoretical model is proposed as a useful tool for experimentalists to predict the limits of improvements in real proteins. © 2013 Wiley Periodicals, Inc.

Reatores eletrônicos para sistemas de iluminação com múltiplas lâmpadas tubulares fluorescentes com controle de luminosidade, elevada eficiência e elevado fator de potência

Pós-graduação em Engenharia Elétrica - FEIS

Análise do desempenho das relações interorganizacionais em arranjos produtivos locais: uma contribuição da análise fatorial exploratória à metodologia da REDESIST no estudo do perfil das relações interorganizacionais desenvolvidas no arranjo produtivo mínero-metalúrgico em Barcarena/PA, no período 2002/2005

Este trabalho tem como objetivo apresentar um estudo das relações inter-firmas estabelecidas entre empresas mínero-metalúrgicas localizadas no distrito industrial do município de Barcarena, no estado do Pará, a partir da análise das interações entre as empresas centrais e suas redes de fornecedores e subcontratados, que operacionalizam o beneficiamento e a exportação de subprodutos dos minerais bauxita e caulim. Segundo as abordagens teóricas que defendem a ocorrência e a disseminação de inovações tecnológicas como base para o desenvolvimento socioeconômico, realizou-se um estudo sobre a forma como os arranjos produtivos são capazes de gerar e manter vantagens competitivas a partir da constituição de sistemas de inovação baseados em redes cooperativas integradas por um grupo específico de agentes públicos e privados. Foram utilizadas técnicas estatísticas de análise descritiva e multivariada – mais especificamente a análise fatorial exploratória, bem como foi efetuada a classificação das empresas segundo o desempenho observado nas dimensões de análise. Estas técnicas têm como finalidade realizar uma investigação de maior nível de complexidade, capaz de detectar elementos comportamentais específicos dos integrantes deste arranjo produtivo em particular, bem como possibilitar a observação individualizada do desempenho das firmas em relação aos fatores latentes identificados através da análise fatorial. O estudo dos fatores foi realizado a partir da análise de seis dimensões conceituais, por meio da qual a massa original de 108 variáveis foi sumarizada em um total de 22 fatores subjacentes. O comportamento e o desempenho das empresas foi então analisado por meio da observação das cargas fatoriais, que refletem a correlação entre as variáveis originais e os fatores identificados. A classificação das firmas foi efetuada por meio da verificação dos escores fatoriais padronizados. Os resultados da pesquisa mostram que, embora os segmentos empresariais estudados apresentem, em média, razoável capacidade competitiva, e empenhem significativos esforços no sentido de obter benefícios da estrutura e do ambiente local, ainda apresentam fraco desempenho em relação às ações de treinamento e aprendizagem e atividades inovativas, assim como registram resultados particularmente ruins em relação ao desenvolvimento de ações cooperativas.Conseqüentemente, a rede de subcontratação desperdiça o potencial de ganhos sinérgicos capazes de elevar os patamares de competitividade local.

Trabalho infantil: uma análise do discurso de crianças e de adolescentes da Amazônia paraense em condição de trabalho

Esta pesquisa privilegia os discursos das crianças e dos adolescentes sobre o trabalho infantil na Grande Região Metropolitana de Belém-PA. O Trabalho Infantil constitui o nosso objeto de pesquisa. Assumimos como referência o conceito marxiano de trabalho como princípio educativo que, no contexto do capitalismo, encontra-se marcado pelo fetichismo da mercadoria. O lócus da pesquisa tem como base as escolas públicas estaduais situadas nos bairros da Terra Firme e de Canudos, que têm crianças e adolescentes com famílias assistidas pelo Programa Bolsa Família. 16 crianças e adolescentes com idades entre 10 e 14 anos participaram da pesquisa. Temos como referência o materialismo histórico e a metodologia tem enfoque qualitativo, do tipo da análise do discurso. Utilizamos como instrumentos para a coleta dos dados um conjunto de técnicas; as atividades de painéis divididas em seções (musical, mural do trabalho e cine prosa), a observação e o grupo focal. Os dados foram organizados em categorias empíricas explicativas do trabalho infantil. Os fundamentos teóricos sobre o trabalho como princípio educativo vieram de Gramsci e de outros pensadores do campo marxista. Na revisão bibliográfica realizada verificamos raros estudos sobre o discurso das crianças e dos adolescentes sobre o trabalho infantil. Os discursos das crianças e dos adolescentes da Amazônia paraense revelam que o trabalho infantil manifesta-se como fonte de sofrimento, como prática social que produz o estranhamento e tendo uma pedagogia própria. Conclui-se que o trabalho infantil forma as crianças e os adolescentes da Amazônia paraense para a lógica capitalista, promovendo a aceitação da sociedade capitalista e como suposto obstáculo aos conflitos e livramento da bandidagem, além de reforçar o discurso do empreendedorismo.

Theoretical investigation of geometric configurations and vibrational spectra in citric acid complexes

The performance of advanced electronic ceramics is directly related to the synthesis route employed. Sol-gel methods are widely used for this purpose. However, the physicochemical intermediate steps are still not well understood. Better understanding and control of these processes can improve the final quality of samples. In this work, we studied theoretically the formation of metal complexes between citric acid and lithium or barium metal cations with different citric acid/metal proportions, using Density Functional Theory electronic structure calculations. Infrared and Raman scattering spectra were simulated for the more stable geometric configurations. Using this methodology, we identified some features of complexes formed in the synthesis process. Our results show that the complexes can be distinguished by changes in the bands assigned to C=O, COH-, and COO- group vibrations. An estimate of the most stable complexes is made based on total energy.

Presence of infectious agents and co-infections in diarrheic dogs determined with a real-time polymerase chain reaction-based panel

Background: Infectious diarrhea can be caused by bacteria, viruses, or protozoan organisms, or a combination of these. The identification of co-infections in dogs is important to determine the prognosis and to plan strategies for their treatment and prophylaxis. Although many pathogens have been individually detected with real-time polymerase chain reaction (PCR), a comprehensive panel of agents that cause diarrhea in privately owned dogs has not yet been established. The objective of this study was to use a real-time PCR diarrhea panel to survey the frequencies of pathogens and co-infections in owned dogs attended in a veterinary hospital with and without diarrhea, as well the frequency in different countries. Feces samples were tested for canine distemper virus, canine coronavirus, canine parvovirus type 2 (CPV-2), Clostridium perfringens alpha toxin (CPA), Cryptosporidium spp., Giardia spp., and Salmonella spp. using molecular techniques.Results: In total, 104 diarrheic and 43 control dogs that were presented consecutively at a major private veterinary hospital were included in the study. Overall, 71/104 (68.3%) dogs with diarrhea were positive for at least one pathogen: a single infection in 39/71 dogs (54.9%) and co-infections in 32/71 dogs (45.1%), including 21/32 dogs (65.6%) with dual, 5/32 (15.6%) with triple, and 6/32 (18.8%) with quadruple infections. In the control group, 13/43 (30.2%) dogs were positive, all with single infections only. The most prevalent pathogens in the diarrheic dogs were CPA (40/104 dogs, 38.5%), CPV-2 (36/104 dogs, 34.6%), and Giardia spp. (14/104 dogs, 13.5%). CPV-2 was the most prevalent pathogen in the dual co-infections, associated with CPA, Cryptosporidium spp., or Giardia spp. No statistical difference (P = 0.8374) was observed in the duration of diarrhea or the number of deaths (P = 0.5722) in the presence or absence of single or co-infections.Conclusions: Diarrheic dogs showed a higher prevalence of pathogen infections than the controls. Whereas the healthy dogs had only single infections, about half the diarrheic dogs had co-infections. Therefore, multiple pathogens should be investigated in dogs presenting with diarrhea. The effects of multiple pathogens on the disease outcomes remain unclear because the rate of death and the duration of diarrhea did not seem to be affected by these factors.

Theoretical and experimental study of agricultural spraying using CFD

This paper presents a computational fluid dynamics (CFD) application about the axial fan design used in an agricultural spraying system with a theoretical and experimental analysis of comparative results between the characteristic curves of a fan for several rotations and numerical results for the influence of blade attack angle variation and optimization of the spraying system, both for a same rotation. Flow was considered three-dimensional, turbulent, isothermal, viscous and non-compressible in a steady state, disregarding any influence of the gravity field. The average turbulent field was obtained from the application of time average where the turbulence model required for closing the set of equations was the k-E model. Resolution of all connected phenomena was achieved with the help of a fluid dynamics computer, CFX, which uses the finite volumes technique as a numerical method. In order to validate the theoretical analysis, an experiment was conducted in a circular section of a horizontal wind tunnel, using a Pitot tube for pressure readings. The main results demonstrate that the methodology used, based on CFD techniques, is able to reproduce the phenomenological behavior of an axial fan in a spraying system because results were very reliable and similar to experimentally measured ones.

Humanization of health care: a reflexive theoretical essay based on the philosophy of Emmanuel Lévinas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biomechanical Study in Polyurethane Mandibles of Different Metal Plates and Internal Fixation Techniques, Employed in Mandibular Angle Fractures

The aim of this study was to perform a physicochemical and morphological characterization and compare the mechanical behavior of an experimental Ti-Mo alloy to the analogous metallic Ti-based fixation system, for mandibular angle fractures. Twenty-eight polyurethane mandibles were uniformly sectioned on the left angle. These were divided into 4 groups: group Eng 1P, one 2.0-mm plate and 4 screws 6 mm long; group Eng 2P, two 2.0-mm plates, the first fixed with 4 screws 6 mm long and the second with 4 screws 12 mm long. The same groups were created for the Ti-15Mo alloy. Each group was subjected to linear vertical loading at the first molar on the plated side in a mechanical testing unit. Means and standard deviations were compared with respect to statistical significance using ANOVA. The chemical composition of the Ti-15Mo alloy was close to the nominal value. The mapping of Mo and Ti showed a homogeneous distribution. SEM of the screw revealed machining debris. For the plates, only the cpTi plate undergoes a surface treatment. The metallographic analysis reveals granular microstructure, from the thermomechanical trials. A statistically significant difference was found (P < 0.05) when the comparison between both internal fixation techniques was performed. The 2P technique showed better mechanical behavior than 1P.

An Informatics Technical Note on Interaction of DNA - Graphene Chemical Sensor System as Reaction-Diffusion Wave-Based Computing System in Ionised Gaseous environments and their Applications Using Theoretical Studies and Scientific Computation Overview

The physics of plasmas encompasses basic problems from the universe and has assured us of promises in diverse applications to be implemented in a wider range of scientific and engineering domains, linked to most of the evolved and evolving fundamental problems. Substantial part of this domain could be described by R–D mechanisms involving two or more species (reaction–diffusion mechanisms). These could further account for the simultaneous non-linear effects of heating, diffusion and other related losses. We mention here that in laboratory scale experiments, a suitable combination of these processes is of vital importance and very much decisive to investigate and compute the net behaviour of plasmas under consideration. Plasmas are being used in the revolution of information processing, so we considered in this technical note a simple framework to discuss and pave the way for better formalisms and Informatics, dealing with diverse domains of science and technologies. The challenging and fascinating aspects of plasma physics is that it requires a great deal of insight in formulating the relevant design problems, which in turn require ingenuity and flexibility in choosing a particular set of mathematical (and/or experimental) tools to implement them.