Crowbar System in Doubly Fed Induction Wind Generators

In the last 15 years, the use of doubly fed induction machines in modern variable-speed wind turbines has increased rapidly. This development has been driven by the cost reduction as well as the low-loss generation of Insulated Gate Bipolar Transistors (IGBT). According to new grid code requirements, wind turbines must remain connected to the grid during grid disturbances. Moreover, they must also contribute to voltage support during and after grid faults. The crowbar system is essential to avoid the disconnection of the doubly fed induction wind generators from the network during faults. The insertion of the crowbar in the rotor circuits for a short period of time enables a more efficient terminal voltage control. As a general rule, the activation and the deactivation of the crowbar system is based only on the DC-link voltage level of the back-to-back converters. In this context, the authors discuss the critical rotor speed to analyze the instability of doubly fed induction generators during grid faults.

Importance of considering a material micro-failure criterion in the numerical modelling of the shot peening process applied to parabolic leaf springs

Shot peening is a cold-working mechanical process in which a shot stream is propelled against a component surface. Its purpose is to introduce compressive residual stresses on component surfaces for increasing the fatigue resistance. This process is widely applied in springs due to the cyclical loads requirements. This paper presents a numerical modelling of shot peening process using the finite element method. The results are compared with experimental measurements of the residual stresses, obtained by the X-rays diffraction technique, in leaf springs submitted to this process. Furthermore, the results are compared with empirical and numerical correlations developed by other authors.

Bioassay guided purification of the antimicrobial fraction of a Brazilian propolis from Bahia state

Background: Brazilian propolis type 6 (Atlantic forest, Bahia) is distinct from the other types of propolis especially due to absence of flavonoids and presence of other non-polar, long chain compounds, but presenting good in vitro and in vivo antimicrobial activity. Several authors have suggested that fatty acids found in this propolis might be responsible for its antimicrobial activity; however, so far no evidence concerning this finding has been reported in the literature. The goals of this study were to evaluate the antibacterial activity of the main pure fatty acids in the ethanolic extract and fractions and elucidate the chemical nature of the bioactive compounds isolated from Brazilian propolis type 6. Methods: Brazilian propolis type 6 ethanolic extract (EEP), hexane fraction (H-Fr), major fatty acids, and isolated sub-fractions were analyzed using high performance liquid chromatography (HPLC), high resolution gas chromatography with flame ionization detection (HRGC-FID), and gas chromatography-mass spectrometry (GC-MS). Three sub-fractions of H-Fr were obtained through preparative HPLC. Antimicrobial activity of EEP, H-Fr, sub-fractions, and fatty acids were tested against Staphyloccus aureus ATCC 25923 and Streptococcus mutans Ingbritt 1600 using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results: EEP and H-Fr inhibited the growth of the microorganisms tested; nevertheless, no antimicrobial activity was found for the major fatty acids. The three sub-fractions (1, 2, and 3) were isolated from H-Fr by preparative HPLC and only sub-fraction 1 showed antimicrobial activity. Conclusion: a) The major fatty acids tested were not responsible for the antimicrobial activity of propolis type 6; b) Sub-fraction 1, belonging to the benzophenone class, was responsible for the antimicrobial activity observed in the present study. The identification of the bioactive compound will improve the development of more efficient uses of this natural product.

Dez anos de parâmetros curriculares nacionais: a prática da Educação Física na visão dos seus autores

The study checked possible theory-methodologic assumptions into Physical Education PCNs by the teachers of the last years of elementary school. The analyses in the publishing allow us to identify the different didactic procedures when compared with those which set up the traditional expectations. From these elements and using the projective method, it was developed an interview with focal group. The data obtained showed us docent perceptions which rearrange the educative practice, and interpretation allows us to realize which of the teachers views approaches the propositions in the official document, even if no reference has been done to it.

Dez anos de pesquisa contábil no Brasil: análise dos trabalhos apresentados nos Enanpads de 1996 a 2005

This paper analyzes the temporal evolution of scientific accounting research in Brazil and the relationship between as not-motive and positive approaches. In order to do so, this study was based on documental descriptive research of papers submitted at the Annual Meeting of the National Association of the Post-Graduation Programs in Management (ENANPADs), from 1996 to 2005. Bibliometrics (Lotka's Law) was used to assess the productivity of the authors of the papers. The results are consistent with the results obtained by Fulbier and Sellhorn (2006) in Europe and reveal that authors predominantly adopt a positive approach,few researchers use the two approaches and confirm that Brazilian researchers have a lower productivity in comparison to those who publish in English-language periodicals.

Gestão do Conhecimento: a produção científica em períodos brasileiros entre 1997 e 2006

This study analyzes how the subject ""Knowledge Management"" (KM) has been published by authors of the Information Science (IS) and Administration (ADM). The research identifies the most productive periodicals, the most prolific institutions and authors in each area, as well as the results obtained. This is a study that presents the mapping of the Brazilian scientific production on KM, in national periodicals level A from CAPES, in the IS and ADM areas. The study is divided into three periods: 1997-2006, 1997-2001 and 2002-2006. The theoretical foundation is based on Nonaka and Takeuchi, Davenport and Prusak, Davenport and Cronin. Seventy-six articles are analyzed, forty in the IS area and thirty-six in the ADM area. The results indicate that the IS has published much more on the subject KM than the ADM. Although the chart presented is not exhaustive, it represents an important sample of the Brazilian scientific production on KM, from 1997-2006.

Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling

Background: With nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity. Results: In the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered incertae sedis in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses. Conclusion: A monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance across the Neotropics and portions of Africa.

INTERPOPULATION COMPARISON OF REPRODUCTION OF THE ATLANTIC SHRIMP HIPPOLYTE OBLIQUIMANUS (CARIDEA: HIPPOLYTIDAE)

The genus Hippolyte is represented by typically small shrimps with intriguing mechanisms of reproduction. In order to study possible variability in reproductive aspects among different populations, we conducted an exhaustive comparative study of H. obliquimanus from South (Brazil) and Central American (Costa Rica) waters. The study focuses on fecundity and reproductive output. Mean size of ovigerous females was significantly larger, and both mean reproductive output and mean fecundity were significantly higher in specimens from Costa Rica then in those collected in Brazil. Embryo volume was significantly smaller in the Costa Rican population, and in both populations embryos doubled their volume during embryogenesis. We discuss and compare our findings with the information available regarding H. obliquimanus and other hippolytid shrimp. The reproductive traits of both populations of H. obliquimanus show some important differences which may reflect adaptations to local environmental conditions, demonstrating a high plasticity of reproductive features of the species in Brazilian and Costa Rican waters.

Pessoa e Pirandello: confluência de dramas

The present study aims to compare two modern authors - Luigi Pirandello and Fernando Pessoa - from different cultural environments - Italy / Brazil - pointing to a common theme: the various levels of the individual's expression. The arguments to support the proposed analysis are based on the shifting literary genres, specifically on the non-dramatic characters by Pirandello and on the drama in people by Pessoa.

Aerobic capacity and skeletal muscle function in children with asthma

Background Peripheral muscle strength and endurance are decreased in patients with chronic pulmonary diseases and seem to contribute to patients' exercise intolerance. However, the authors are not aware of any studies evaluating peripheral muscle function in children with asthma. It seems to be implied that children with asthma have lower aerobic fitness, but there are limited studies comparing the aerobic capacity of children with and without asthma. The present study aimed to evaluate muscle strength and endurance in children with persistent asthma and their association with aerobic capacity and inhaled corticosteroid consumption. Methods Forty children with mild persistent asthma (MPA) or severe persistent asthma (SPA) (N=20 each) and 20 children without asthma (control group) were evaluated. Upper (pectoralis and latissimus dorsi) and lower (quadriceps) muscle strength and endurance were assessed, and cardiopulmonary exercise testing was performed. Inhaled corticosteroid consumption during the last 6 and 24 months was also quantified. Results Children with SPA presented a reduction in peak oxygen consumption (VO(2)) (28.2 +/- 8.1 vs 34.7 +/- 6.9 ml/kg/min; p<0.01) and quadriceps endurance (43.1 +/- 6.7 vs 80.9 +/- 11.9 repetitions; p<0.05) compared with the control group, but not the MPA group (31.5 +/- 6.1 ml/kg/min and 56.7 +/- 47.7 repetitions respectively; p>0.05). Maximal upper and lower muscle strength was preserved in children with both mild and severe asthma (p>0.05). Finally, the authors observed that lower muscle endurance weakness was not associated with reductions in either peak VO(2) (r=0.22, p>0.05) or corticosteroid consumption (r=-0.31, p>0.05) in children with asthma. Conclusion The findings suggest that cardiopulmonary exercise and lower limb muscle endurance should be a priority during physical training programs for children with severe asthma.

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and high plasma homocysteine in chronic hepatitis C (CHC) infected patients from the Northeast of Brazil

Background/Aim: Hyperhomocysteinemia due to Methylenetetrahydrofolate Reductase (MTHFR) gene, in particular the C677T (Ala222Val) polymorphism were recently associated to steatosis and fibrosis. We analyzed the frequency of MTHFR gene in a cross-sectional study of patients affected by Chronic Hepatitis C (CHC) from Northeast of Brazil. Method: One hundred seven-four untreated patients with CHC were genotyped for the C677T MTHFR. Genomic DNA was extracted from peripheral blood cells and the C677T MTHFR polymorphism was identified by PCR-RFLP. The homocysteine (Hcy) levels were determined by chemiluminescence method. All patients were negative for markers of Wilson's disease, hemochromatosis and autoimmune diseases and have current and past daily alcohol intake less than 100 g/week. Results: Among subjects infected with CHC genotype non-1 the frequency of MTHFR genotypes TT was 9.8% versus 4.4% genotype 1 (p = 0.01). Nevertheless, association was found between the MTHFR genotype TT x CT/CC polymorphism and the degree of steatosis and fibrosis in both hepatitis C genotype (p < 0.05). A significant difference was found on plasma Hcy levels in patients with steatosis regardless of HCV genotype (p = 0.03). Conclusion: Our results indicate that plasma Hcy levels is highly prevalent in subjects with chronic hepatits C with steatosis regardless of HCV genotype and vitamin deficiency. The presence of genotype TT of MTHFR C677T polymorphism was more common in CHC genotype non-1 infected patient regardless of histopathological classification and genotype TT+CT frequencies were significant in the presence of fibrosis grade 1+2 and of steatosis in CHC infected patients from the northeast of Brazil regardless of HCV genotype. The genetic susceptibility of MTHFR C677T polymorphism should be confirmed in a large population.

Proteome analysis of schizophrenia patients Wernicke's area reveals an energy metabolism dysregulation

Background: Schizophrenia is likely to be a consequence of DNA alterations that, together with environmental factors, will lead to protein expression differences and the ultimate establishment of the illness. The superior temporal gyrus is implicated in schizophrenia and executes functions such as the processing of speech, language skills and sound processing. Methods: We performed an individual comparative proteome analysis using two-dimensional gel electrophoresis of 9 schizophrenia and 6 healthy control patients' left posterior superior temporal gyrus (Wernicke's area - BA22p) identifying by mass spectrometry several protein expression alterations that could be related to the disease. Results: Our analysis revealed 11 downregulated and 14 upregulated proteins, most of them related to energy metabolism. Whereas many of the identified proteins have been previously implicated in schizophrenia, such as fructose-bisphosphate aldolase C, creatine kinase and neuron-specific enolase, new putative disease markers were also identified such as dihydrolipoyl dehydrogenase, tropomyosin 3, breast cancer metastasis-suppressor 1, heterogeneous nuclear ribonucleoproteins C1/C2 and phosphate carrier protein, mitochondrial precursor. Besides, the differential expression of peroxiredoxin 6 (PRDX6) and glial fibrillary acidic protein (GFAP) were confirmed by western blot in schizophrenia prefrontal cortex. Conclusion: Our data supports a dysregulation of energy metabolism in schizophrenia as well as suggests new markers that may contribute to a better understanding of this complex disease.

Development and mechanical testing of a short intramedullary nail for fixation of femoral rotational osteotomy in cerebral palsy patients

Background: Rotational osteotomy is frequently indicated to correct excessive femoral anteversion in cerebral palsy patients. Angled blade plate is the standard fixation device used when performed in the proximal femur, but extensile exposure is required for plate accommodation. The authors developed a short locked intramedullary nail to be applied percutaneously in the fixation of femoral rotational osteotomies in children with cerebral palsy and evaluated its mechanical properties. Methods: The study was divided into three stages. In the first part, a prototype was designed and made based on radiographic measurements of the femoral medullary canal of ten-year-old patients. In the second, synthetic femoral models based on rapid-prototyping of 3D reconstructed images of patients with cerebral palsy were obtained and were employed to adjust the nail prototype to the morphological changes observed in this disease. In the third, rotational osteotomies were simulated using synthetic femoral models stabilized by the nail and by the AO-ASIF fixed-angle blade plate. Mechanical testing was done comparing both devices in bending-compression and torsion. Results: The authors observed proper adaptation of the nail to normal and morphologically altered femoral models, and during the simulated osteotomies. Stiffness in bending-compression was significantly higher in the group fixed by the plate (388.97 +/- 57.25 N/mm) than in that fixed by the nail (268.26 +/- 38.51 N/mm) as torsional relative stiffness was significantly higher in the group fixed by the plate (1.07 +/- 0.36 Nm/degrees) than by the nail (0.35 +/- 0.13 Nm/degrees). Conclusions: Although the device presented adequate design and dimension to fit into the pediatric femur, mechanical tests indicated that the nail was less stable than the blade plate in bending-compression and torsion. This may be a beneficial property, and it can be attributed to the more flexible fixation found in intramedullary devices.

An insight into the sialotranscriptome of the brown dog tick, Rhipicephalus sanguineus

Background: Rhipicephalus sanguineus, known as the brown dog tick, is a common ectoparasite of domestic dogs and can be found worldwide. R. sanguineus is recognized as the primary vector of the etiological agent of canine monocytic ehrlichiosis and canine babesiosis. Here we present the first description of a R. sanguineus salivary gland transcriptome by the production and analysis of 2,034 expressed sequence tags (EST) from two cDNA libraries, one consctructed using mRNA from dissected salivary glands from female ticks fed for 3-5 days (early to mid library, RsSGL1) and the another from ticks fed for 5 days (mid library, RsSGL2), identifying 1,024 clusters of related sequences. Results: Based on sequence similarities to nine different databases, we identified transcripts of genes that were further categorized according to function. The category of putative housekeeping genes contained similar to 56% of the sequences and had on average 2.49 ESTs per cluster, the secreted protein category contained 26.6% of the ESTs and had 2.47 EST's/clusters, while 15.3% of the ESTs, mostly singletons, were not classifiable, and were annotated as ""unknown function"". The secreted category included genes that coded for lipocalins, proteases inhibitors, disintegrins, metalloproteases, immunomodulatory and antiinflammatory proteins, as Evasins and Da-p36, as well as basic-tail and 18.3 kDa proteins, cement proteins, mucins, defensins and antimicrobial peptides. Comparison of the abundance of ESTs from similar contigs of the two salivary gland cDNA libraries allowed the identification of differentially expressed genes, such as genes coding for Evasins and a thrombin inhibitor, which were over expressed in the RsSGL1 (early to mid library) versus RsSGL2 (mid library), indicating their role in inhibition of inflammation at the tick feeding site from the very beginning of the blood meal. Conversely, sequences related to cement (64P), which function has been correlated with tick attachment, was largely expressed in the mid library. Conclusions: Our survey provided an insight into the R. sanguineus sialotranscriptome, which can assist the discovery of new targets for anti-tick vaccines, as well as help to identify pharmacologically active proteins.

Low-Level Laser Therapy on the Viability of Skin Flap in Rats Subjected to Deleterious Effect of Nicotine

Objective: The purpose of this study was to evaluate the effect of 830-nm laser in blocking the action of nicotine on the viability of skin flap. Background data: The authors have analyzed the deleterious effect of cigarette smoke or nicotine on the skin flap alone with evidence of increased skin necrosis in the flap. Materials and methods: Twenty-four Wistar-albino rats were divided into three groups of eight animals each: Group 1 (control), subjected to a surgical technique to obtain a flap for cranial base, laser irradiation simulation, and a subcutaneous injection of saline; Group 2, similar to Group 1, with subcutaneous injection of nicotine (2mg/kg/day) for a period of 1 week before and 1 week after surgery; and Group 3, similar to Group 2, with skin flaps subjected to a lambda 830-nm laser irradiation. The laser parameters used were: power 30 mW, beam area 0.07cm(2), irradiance 429 mW/cm(2), irradiation time 84 sec, total energy 2.52J, and energy density 36J/cm(2). The laser was used immediately after surgery and for 4 consecutive days, in one point at 2.5 cm of the flap cranial base. The areas of necrosis were examined by two macroscopic analyses: paper template and Mini-Mop (R). The pervious blood vessels were also counted. Results: The results were statistically analyzed by ANOVA and post-test contrast orthogonal method (multiple comparisons), showing that the laser decreased the area of necrosis in flaps subjected to nicotine, and consequently, increased the number of blood vessels (p < 0.05). Conclusions: The laser proved to be an effective way to decrease the area of necrosis in rats subjected to nicotine, making them similar to the control group.