Numerical simulations of the Princeton magneto-rotational instability experiment with conducting axial boundaries

We investigate numerically the Princeton magneto-rotational instability (MRI) experiment and the effect of conducting axial boundaries or endcaps. MRI is identified and found to reach a much higher saturation than for insulating endcaps. This is probably due to stronger driving of the base flow by the magnetically rather than viscously coupled boundaries. Although the computations are necessarily limited to lower Reynolds numbers ($\Re$) than their experimental counterparts, it appears that the saturation level becomes independent of $\Re$ when $\Re$ is sufficiently large, whereas it has been found previously to decrease roughly as $\Re^{-1/4}$ with insulating endcaps. The much higher saturation levels will allow for the first positive detection of MRI beyond its theoretical and numerical predictions

The influence of insertion torque on pedicular screws' pullout resistance

Foram realizados ensaios mecânicos para avaliação do torque de inserção na resistência ao arrancamento dos parafusos pediculares. Foram utilizadas no estudo 30 vértebras de suínos da raça Landrace, nas quais parafusos de 5mm foram inseridos nos pedículos vertebrais. O orifício piloto foi realizado com brocas de 2,5mm, 3,8mm e 4,5mm. Foram realizados ensaios mecânicos de arrancamento dos implantes em máquina universal de testes. Foi observado aumento do torque de inserção dos parafusos com a perfuração do orifício piloto com diâmetro menor que o diâmetro interno do parafuso, e redução com o orifício piloto maior que o diâmetro interno do parafuso. Foi observada diferença estatística entre os valores do torque de inserção. A resistência ao arrancamento dos implantes aumentou com a perfuração do orifício piloto com valores menores que o diâmetro interno do parafuso e diminuiu com a perfuração com diâmetro maior que o diâmetro interno do parafuso. Foi observada diferença estatística dos valores da resistência ao arrancamento dos implantes apenas com a perfuração do orifício piloto com diâmetro maior que o diâmetro interno do parafuso.Mechanical assays were performed in order to evaluate the effect of the insertion torque on the pullout resistance of pedicular screws. Thirty vertebrae of Landrace pigs were used in the study, with 5-mm screws being inserted into the vertebral pedicles. The pilot hole was drilled with 1.5, 3.8 and 4.5 mm burrs. Mechanical assays of implant pullout resistance were performed with a universal testing machine. An increase in the insertion torque of the screws was observed when a pilot hole with a smaller diameter than the inner diameter of the screw was drilled, and a reduction was observed when the diameter of the pilot hole was larger than the inner diameter of the screw. A statistically significant difference in the insertion torque values was observed. The pullout resistance of the implants increased when the pilot hole had a smaller diameter than the inner diameter of the screw and decreased when the pilot hole had a larger diameter than the inner diameter of the screw. A statistically significant difference in implant pullout resistance was observed only when the diameter of the pilot hole was larger than the inner diameter of the screw.FAPESCAPES - PROBRA

Measurement of retinal vessels as a biomarker of cerebrovascular ageing in older HIV positive men compared to controls

Background: To compare retinal vascular measurements, biomarkers of cerebral small vessel disease (SVD), in HIV positive men aged 50 years and above with similarly-aged HIV negative men and younger HIV positive men. Methods: We recruited white, non-diabetic men to a cross-sectional substudy of a larger cohort including three demographically-matched groups. Optic disc centred 45° colour fundus photographs were used to calculate central retinal arterial and venous calibre and the arterial- venous ratio (AVR). We used univariate and multivariable linear regression to compare retinal vessel measurements in the three groups and to identify factors associated with AVR. Results: All HIV positive men were virologically suppressed. In a multivariable model, study group was not associated with AVR (adjusted β 0.010 for HIV positive men 50 years [n=120], 95% CI -0.018 to 0.038, p=0.47; adjusted β 0.00002 for HIV negative men >50 years [n=52], 95% CI -0.022 to 0.022, p=0.99). Factors associated with lower AVR were systolic BP (adjusted β -0.009 per +10 mmHg, 95% CI - 0.015 to -0.003, p=0.002), history of stroke or transient ischemic attack (adjusted β -0.070, 95% CI -0.12 to -0.015, p=0.01), and recent recreational drug use (adjusted β -0.037, 95% CI -0.057 to -0.018, p=0.0002). Conclusion: There were no differences in retinal vascular indices between HIV positive men aged >50 years and HIV negative men aged >50 years or HIV positive men aged <50 years, suggesting that HIV is not associated with an increased burden of cerebral SVD

Ensinar e aprender Química: a percepção de professores de Ensino Médio

O presente trabalho buscou investigar a percepção dos professores da educação básica sobre as práticas pedagógicas em sala de aula e na escola, as dificuldades enfrentadas e as possíveis maneiras de solucioná-las, assim como as formas por eles utilizadas para se manterem atualizados. A investigação envolveu 93 professores do Ensino Médio de escolas do estado de Minas Gerais, durante a realização da Olimpíada Mineira de Química (OMQ) 2008. A análise dos comentários feitos pelos professores, no instrumento de coleta de dados utilizado, mostrou que os mesmos tendem a associar as dificuldades que enfrentam principalmente à escola, aos alunos e a questões externas à escola, ou seja, não se assumem como parte dos problemas. Percebemos, também, que associam as principais melhorias na educação básica à infra-estrutura da escola e que nem todos participaram de eventos que promovessem a atualização profissional nos últimos dois anos.The present study aimed at investigating the perception of high school teachers in pedagogical practices in classrooms and in schools. It evaluates the difficulties encountered by teachers and possible ways to solve them, as well as how teachers keep themselves up to date. The research involved 93 high school teachers in the schools of the state of Minas Gerais, during the Chemistry Olympiad of the State of Minas Gerais  (OMQ) 2008. The analysis of teachers’ comments showed that they tend to associate the problems they encounter to school, students and questions outside the school, in other words, they do not  see themselves as part of the problems. We perceive that teachers associate most improvements in education to school facilities and that they have not participated in upgrading courses, meetings or other discussions, as a means of professional updating in the last two years

Aprendizagem e Competição: A Olimpíada Mineira de Química na Visão dos Professores de Ensino Médio

A ocorrência da olimpíada científica de Química na Universidade Federal de Minas Gerais (UFMG) trouxe à tona, junto à equipe organizadora, questionamentos sobre sua importância e impactos. O presente trabalho foi realizado com professores da educação básica, cujos estudantes participaram da olimpíada, com o objetivo de identificar a percepção destes sobre a competição e o que ela representa. A concepção dos professores sobre esse processo competitivo evidencia uma estratégia para engajar os estudantes. Ressaltamos que a competitividade deve ser trabalhada com ressalvas e que a cooperação deve fazer parte do processo. Além disso, percebemos que há poucas situações na escola capazes de engajar os estudantes para a aprendizagem de Química e que a olimpíada significou uma possibilidade para tal

Rules for Growth: Promoting Innovation and Growth Through Legal Reform

The United States economy is struggling to recover from its worst economic downturn since the Great Depression. After several huge doses of conventional macroeconomic stimulus - deficit-spending and monetary stimulus - policymakers are understandably eager to find innovative no-cost ways of sustaining growth both in the short and long runs. In response to this challenge, the Kauffman Foundation convened a number of America’s leading legal scholars and social scientists during the summer of 2010 to present and discuss their ideas for changing legal rules and policies to promote innovation and accelerate U.S. economic growth. This meeting led to the publication of Rules for Growth: Promoting Innovation and Growth Through Legal Reform, a comprehensive and groundbreaking volume of essays prescribing a new set of growth-promoting policies for policymakers, legal scholars, economists, and business men and women. Some of the top Rules include: • Reforming U.S. immigration laws so that more high-skilled immigrants can launch businesses in the United States. • Improving university technology licensing practices so university-generated innovation is more quickly and efficiently commercialized. • Moving away from taxes on income that penalize risk-taking, innovation, and employment while shifting toward a more consumption-based tax system that encourages saving that funds investment. In addition, the research tax credit should be redesigned and made permanent. • Overhauling local zoning rules to facilitate the formation of innovative companies. • Urging judges to take a more expansive view of flexible business contracts that are increasingly used by innovative firms. • Urging antitrust enforcers and courts to define markets more in global terms to reflect contemporary realities, resist antitrust enforcement from countries with less sound antitrust regimes, and prohibit industry trade protection and subsidies. • Reforming the intellectual property system to allow for a post-grant opposition process and address the large patent application backlog by allowing applicants to pay for more rapid patent reviews. • Authorizing corporate entities to form digitally and use software as a means for setting out agreements and bylaws governing corporate activities. The collective essays in the book propose a new way of thinking about the legal system that should be of interest to policymakers and academic scholars alike. Moreover, the ideas presented here, if embodied in law, would augment a sustained increase in U.S. economic growth, improving living standards for U.S. residents and for many in the rest of the world

Transient Protein-Protein Interaction of the SH3-Peptide Complex via Closely Located Multiple Binding Sites

Protein-protein interactions play an essential role in cellular processes. Certain proteins form stable complexes with their partner proteins, whereas others function by forming transient complexes. The conventional protein-protein interaction model describes an interaction between two proteins under the assumption that a protein binds to its partner protein through a single binding site. In this study, we improved the conventional interaction model by developing a Multiple-Site (MS) model in which a protein binds to its partner protein through closely located multiple binding sites on a surface of the partner protein by transiently docking at each binding site with individual binding free energies. To test this model, we used the protein-protein interaction mediated by Src homology 3 (SH3) domains. SH3 domains recognize their partners via a weak, transient interaction and are therefore promiscuous in nature. Because the MS model requires large amounts of data compared with the conventional interaction model, we used experimental data from the positionally addressable syntheses of peptides on cellulose membranes (SPOT-synthesis) technique. From the analysis of the experimental data, individual binding free energies for each binding site of peptides were extracted. A comparison of the individual binding free energies from the analysis with those from atomistic force fields gave a correlation coefficient of 0.66. Furthermore, application of the MS model to 10 SH3 domains lowers the prediction error by up to 9% compared with the conventional interaction model. This improvement in prediction originates from a more realistic description of complex formation than the conventional interaction model. The results suggested that, in many cases, SH3 domains increased the protein complex population through multiple binding sites of their partner proteins. Our study indicates that the consideration of general complex formation is important for the accurate description of protein complex formation, and especially for those of weak or transient protein complexes

Professor de ensino superior: o entendimento a partir de narrativas de pós-graduandos em química

The quality of higher education has raised growing interest among researchers and experts in education. In the present work we have emphasized the correlation between the growing specialization offered by graduate programs in Chemistry and the improvement in the quality of university teachers, trying to understand how the graduate students themselves imagine the teaching activity. For that, graduate students in Chemistry from the Federal University of Minas Gerais were invited to construct narratives about a fictitious situation in which they imagined themselves as teachers. The analysis of the reports was made by grouping the facts described under three categories: the preparation for approval in the admission exam, the classes taught, and the activities developed during the first four months of work. Results have shown that students pay less attention to the teaching activity and tend to value research and the activities that foster it. This shows that future professionals, even taking up the post of teachers, are more predisposed to act as researchers than to exercise the teaching activity. Such indication seems to be related to the demands made during the selection process for higher education teachers and to the current work situation in most universities, which evaluate qualitatively the intellectual production in the form of articles, whereas classes are evaluated in a more quantitative manner.A qualidade do ensino superior tem despertado cada vez mais o interesse de pesquisadores e especialistas em educação. Neste trabalho, foi enfatizada a correlação entre a crescente especialização oferecida pelos programas de pós-graduação em química e a melhoria da qualidade docente dos professores universitários, procurando entender como os próprios pós-graduandos imaginam ser a atividade docente. Para isso, os estudantes de pós-graduação em química da Universidade Federal de Minas Gerais foram convidados a construir uma narrativa sobre uma situação fictícia em que se imaginavam professores. A análise dos relatos foi realizada agrupando-se os fatos narrados em três categorias: a preparação para aprovação no concurso, as aulas ministradas e as atividades desenvolvidas durante os quatro primeiros meses de trabalho. Os resultados mostraram que os estudantes dão menos atenção à atividade docente e tendem a valorizar a pesquisa e as atividades que a dinamizam. Isso evidencia que os futuros profissionais, mesmo assumindo o cargo de professor, estão mais predispostos a atuarem como pesquisadores do que a exercerem a docência. Tal indício parece estar relacionado com as exigências dos processos de seleção de professores de ensino superior e com o funcionamento atual da maior parte das universidades, que avaliam em termos qualitativos a produção intelectual na forma de artigos, ao passo que as aulas são avaliadas em seu caráter mais quantitativo