Search for violation of Lorentz invariance in top quark pair production and decay

Using data collected with the D0 detector at the Fermilab Tevatron Collider, corresponding to 5.3fb -1 of integrated luminosity, we search for violation of Lorentz invariance by examining the tt̄ production cross section in lepton+jets final states. We quantify this violation using the standard-model extension framework, which predicts a dependence of the tt̄ production cross section on sidereal time as the orientation of the detector changes with the rotation of the Earth. Within this framework, we measure components of the matrices (c Q) μν33 and (c U) μν33 containing coefficients used to parametrize violation of Lorentz invariance in the top quark sector. Within uncertainties, these coefficients are found to be consistent with zero. © 2012 American Physical Society.

Ethanolic extract of Mimosa caesalpiniifolia leaves: Chemical characterization and cytotoxic effect on human breast cancer MCF-7 cell line

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

Multiplex-PCR for differentiation of Mycobacterium bovis from Mycobacterium tuberculosis complex

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

A geometria da Esponja de Menger

Neste trabalho estudaremos algumas propriedades geom´etricas do fractal “Esponja de Menger”, que é um objeto matemático construído através de um processo recursivo infinito que o torna auto-semelhante. Além disso, a dimens˜ao de um fractal n˜ao é necessariamente um número inteiro, diferentemente do que ocorre com os objetos da Geometria Euclidiana. Mais ainda, a Esponja possui área infinita e volume nulo, fatos que demonstraremos ao longo deste texto.

Genes differentially expressed by Mycobacterium tuberculosis after exposure to ruthenium phosphinic compound and isoniazid

Background- The evaluation of the effects of new compounds and nonconventional anti-tuberculous drugs have grown and become increas-ingly more popular in recent years. Studies have shown anti-tuberculous activity for Ruthenium complexes, including organometallic com-pounds containing phosphine ligands such as picolinic acid generating great expectations and hopes. Methods- The Representational Difference Analysis (RDA) was applied in order to gain insight about differences in expression of Mycobacte-rium tuberculosis H37Rv exposed to [Ru(dppb)(pic)(bypy)] PF6 (SCAR1) and isoniazid (INH). Total RNA was extracted from the bacillus not exposed and exposed to SCAR1 and INH separately at concentration of MIC for 12 hours at 35°C. RDA was carried out and differentially expressed products were sequenced. Results- RDA-sequencing identified, for both compounds, orthologs that encode hypothetical and predict proteins. One related cell wall syn-thesis gene, identified by RDA, and genes related to INH target as inhA, katG and ahpC had their expression confirmed and quantified by real-time PCR. The gene encoding the cell wall associated hydrolase was induced 4.627 and 1.189, inhA 0.983 and 1.027, katG 1.111 and 1.345 and ahpC 1.063 and 1.039 fold after exposure to SCAR1 and INH respectively, compared to not exposed growth. Conclusion- The RDA brings, for the first time, directions to study related genes with metabolic pathways of SCAR1. RDA and Real-Time PCR highlight the idea that one of the SCAR1 interaction, in M tuberculosis may be in the cell wall biosynthesis considering the differential expression of a cell wall hydrolase and warrants further investigation.

GeoGebra e o método de Briot & Bouquet para a resolução gráfica de equações cúbicas

In the mid-nineteenth century, french mathematicians Briot and Bouquet have proposed an intriguing graphical method for solving cubic equations "depressed" - the third degree equations that do not have the quadratic term. The proposal is simple geometric construction, though based on an ingenious algebra. We propose here the verification and testing graphical method through an instructional sequence using the software GeoGebra also present the ingenious algebraic development that resulted in this graphic method for determination of real roots of a cubic equation of the type x³ + px + q = 0 where p and q are real numbers. The method states that these solutions are summarized in the abscissas of the points of intersection of the circumference containing the origin and the center C (-q/2, 1-p/2) with the parable y = x².

Ensino de geometria espacial na licenciatura em matemática: uma proposta de trabalho com grupos colaborativos

Apresenta-se neste trabalho experiências obtidas através de 06 (seis) anos consecutivos de trabalho com a disciplina de Geometria Espacial em turmas de formação inicial de professores de matemática. A proposta de trabalho em grupos colaborativos se justifica pela necessidade atual de os professores em atividade utilizarem essa poderosa ferramenta como facilitadora da aprendizagem pessoal e dos estudantes sob sua orientação. Os alunos das várias turmas foram desafiados à tarefa de apresentarem, ao final da disciplina (semestre), um trabalho contendo: material escrito (capa, formatação, desenvolvimento do tema, cálculos, desenhos, resultados e referências), material concreto produzido com canudos e fitilho (sólidos construídos: acabamento, uniformização, montagem e medidas) e apresentação oral do grupo (arquivos de programas de apresentação). A metodologia proposta para a realização dessa tarefa em todas as turmas foi de grupos colaborativos, com em média 05 (cinco) alunos cada. Para a 1ª turma foi proposta a construção de “esqueletos” dos poliedros de Platão, com a maior aresta (canudinho) fixada. Cada grupo deveria observar uma propriedade dentre as seguintes: sólidos com a mesma área total; com o mesmo volume; com uma mesma esfera inscrita e com uma mesma esfera circunscrita. Todo material coletado dos grupos (escrito, construído ou digital/apresentação oral), está sendo devidamente catalogado, para então ser disponibilizado no Laboratório de Ensino de Matemática do referido curso. Os trabalhos propostos posteriormente foram gradativamente sendo mais desafiadores. O último trabalho proposto (2012) teve o seguinte tema: Poliedros Arquimedianos ou semirregulares.

Sobre a compacidade lógica e topológica

Os ambientes da L´ogica e da Topologia tˆem a compacidade como uma propriedade importante. Nos dois diferentes contextos as no¸c˜oes de compacidade s˜ao diversas. Na l´ogica, dizemos que um conjunto de f´ormulas ∆ ´e compacto quando a existˆencia de modelo para todo subconjunto finito de ∆ implica que tamb´em ∆ tem modelo. A l´ogica ´e compacta, se o conjunto de suas f´ormulas v´alidas ´e compacto. Na topologia, um conjunto A ´e compacto, caso qualquer cobertura de A por abertos admita uma subcobertura finita. Neste trabalho, mostramos uma maneira de relacionar tais no¸c˜oes de compacidade.

Jogos no Ensino de Matemática: experiências com o fecha a caixa

Apresentamos neste trabalho experiências obtidas na aplicação de um dos jogos desenvolvidos como parte do projeto de Extensão “Ensinado Matemática através de Jogos, Modelos Geométricos e Informática”, o qual tem como objetivo desenvolver entre os alunos do ensino fundamental e médio o estímulo pelo interesse em Matemática e o aprimoramento de seus conhecimentos nesta área, o que é propiciado através do contato com problemas desafiantes e da interação com outros colegas e docentes, despertando o gosto e interesse pela investigação matemática, através dos jogos, modelos geométricos e softwares. O “Ensinando Matemática através de jogos, modelos geométricos e informática” conta com a colaboração de 3 docentes do departamento de Matemática da UNESP-Bauru e envolve a cidade de Bauru com várias escolas públicas de ensino médio, participando as três séries deste nível. Um dos objetivos dos departamentos de Matemática das universidades brasileiras é estimular o interesse dos graduandos ingressantes pelo raciocínio lógico. Outro ângulo é buscar meios de incentivo para alunos e professores, na tentativa de colaborar para a melhoria do quadro brasileiro que se coloca. Com este projeto estamos estimulando o gosto pela Matemática, propiciando uma maior interação professor / aluno, e promovendo uma aproximação comunidade / universidade, fazendo com que o aluno tenha uma nova visão da Matemática através dos jogos. Assim, de forma lúdica, estamos fazendo com que este aluno pense nos conceitos aprendidos na sala de aula, questione a lógica usada para fazer o pensamento, fazendo com que este estudante crie conexões entre as várias áreas da matemática. Dentre os jogos aplicados, o “fecha a caixa” tem nos proporcionado atingir este objetivo, como apresentamos no decorrer do nosso texto.

Aplicando o jogo Avançando com o resto no Ensino de Matemática

Como é conhecido pela maioria, infelizmente, o ensino de matemática vem enfrentando muitas dificuldades. Cerca o ensino dessa disciplina mitos, preconceitos, que fazem com que o estudante, muitas vezes, já chegue à escola com medo das aulas de matemática. Por outro lado, ainda perdura em muitas escolas um ensino focado na reprodução e não na construção do conhecimento, apesar de alguns professores buscarem alternativas para tornarem as aulas mais atrativas, priorizando atividades interessantes e motivadoras. O famoso livro didático e os caderninhos de apoio enviados pela secretaria do estado da educação ainda continuam sendo os principais recursos disponíveis na sala de aula. Os exercícios e listas, muitas vezes considerados intermináveis, buscam sem sucesso fixar um conhecimento que muitas vezes não foram se quer apropriado pelos alunos. Diante do exposto faz-se necessário pensar em transformações no ensino de matemática que ultrapassem a simples reprodução de exercícios e permitam tanto para o professor, quanto para o aluno um ensino mais atraente e desafiador e principalmente repleto de significados. Dessa forma, este estudo tem como objetivo mostrar ao aluno, a partir dos jogos matemáticos, a diversão e, também, a superação, possibilitando a construção de aprendizagens significativas.

Introdução à teoria de Poincaré-Bendixson para campos de vetores planares

O Teorema de Poincaré-Bendixson é um resultado muito importante no estudo de Sistemas Dinâmicos, pois ele estabelece para quais tipos de conjunto limite as trajetórias de um campo de vetores em IR2 deve convergir. Neste trabalho vamos abordar a Funç˜ao do primeiro Retorno de Poincaré, além de discutir a estabilidade de Ciclos Limites e provar o Teorema de Poincaré-Bendixson.

Classification and regression tree (CART) model to predict pulmonary tuberculosis in hospitalized patients

Background: Tuberculosis (TB) remains a public health issue worldwide. The lack of specific clinical symptoms to diagnose TB makes the correct decision to admit patients to respiratory isolation a difficult task for the clinician. Isolation of patients without the disease is common and increases health costs. Decision models for the diagnosis of TB in patients attending hospitals can increase the quality of care and decrease costs, without the risk of hospital transmission. We present a predictive model for predicting pulmonary TB in hospitalized patients in a high prevalence area in order to contribute to a more rational use of isolation rooms without increasing the risk of transmission. Methods: Cross sectional study of patients admitted to CFFH from March 2003 to December 2004. A classification and regression tree (CART) model was generated and validated. The area under the ROC curve (AUC), sensitivity, specificity, positive and negative predictive values were used to evaluate the performance of model. Validation of the model was performed with a different sample of patients admitted to the same hospital from January to December 2005. Results: We studied 290 patients admitted with clinical suspicion of TB. Diagnosis was confirmed in 26.5% of them. Pulmonary TB was present in 83.7% of the patients with TB (62.3% with positive sputum smear) and HIV/AIDS was present in 56.9% of patients. The validated CART model showed sensitivity, specificity, positive predictive value and negative predictive value of 60.00%, 76.16%, 33.33%, and 90.55%, respectively. The AUC was 79.70%. Conclusions: The CART model developed for these hospitalized patients with clinical suspicion of TB had fair to good predictive performance for pulmonary TB. The most important variable for prediction of TB diagnosis was chest radiograph results. Prospective validation is still necessary, but our model offer an alternative for decision making in whether to isolate patients with clinical suspicion of TB in tertiary health facilities in countries with limited resources.

Prey digestion in the midgut of the predatory bug Podisus nigrispinus (Hemiptera: Pentatomidae)

Pre-oral digestion is described as the liquefaction of the solid tissues of the prey by secretions of the predator. It is uncertain if pre-oral digestion means pre-oral dispersion of food or true digestion in the sense of the stepwise bond breaking of food polymers to release monomers to be absorbed. Collagenase is the only salivary proteinase, which activity is significant (10%) in relation to Podisus nigrispinus midgut activities. This suggests that pre-oral digestion in P. nigrispinus consists in prey tissue dispersion. This was confirmed by the finding of prey muscles fibers inside P. nigrispinus midguts. Soluble midgut hydrolases from P. nigrispinus were partially purified by ion-exchange chromatography, followed by gel filtration. Two cathepsin L-like proteinases (CAL1 and CAL2) were isolated with the properties: CAL1 (14.7 kDa, pH optimum (pHo) 5.5, km with carbobenzoxy-Phe-Arg-methylcoumarin, Z-FR-MCA, 32 mu M); CAL2 (17 kDa, pHo 5.5, km 11 mu M Z-FR-MCA). Only a single molecular species was found for the other enzymes with the following properties are: amylase (43 kDa, pHo 5.5, km 0.1% starch), aminopeptidase (125 kDa, pHo 5.5, km 0.11 mM L-Leucine-p-nitroanilide), alpha-glucosidase (90 kDa, pHo 5.0, km 5 mM with p-nitrophenyl alpha-D-glucoside). CAL molecular masses are probably underestimated due to interaction with the column. Taking into account the distribution of hydrolases along P. nigrispinus midguts, carbohydrate digestion takes place mainly at the anterior midgut, whereas protein digestion occurs mostly in middle and posterior midgut, as previously described in seed- sucker and blood-feeder hemipterans. (C) 2012 Elsevier Ltd. All rights reserved.

Validation of reference genes for RT-qPCR normalization in common bean during biotic and abiotic stresses

Selection of reference genes is an essential consideration to increase the precision and quality of relative expression analysis by the quantitative RT-PCR method. The stability of eight expressed sequence tags was evaluated to define potential reference genes to study the differential expression of common bean target genes under biotic (incompatible interaction between common bean and fungus Colletotrichum lindemuthianum) and abiotic (drought; salinity; cold temperature) stresses. The efficiency of amplification curves and quantification cycle (C (q)) were determined using LinRegPCR software. The stability of the candidate reference genes was obtained using geNorm and NormFinder software, whereas the normalization of differential expression of target genes [beta-1,3-glucanase 1 (BG1) gene for biotic stress and dehydration responsive element binding (DREB) gene for abiotic stress] was defined by REST software. High stability was obtained for insulin degrading enzyme (IDE), actin-11 (Act11), unknown 1 (Ukn1) and unknown 2 (Ukn2) genes during biotic stress, and for SKP1/ASK-interacting protein 16 (Skip16), Act11, Tubulin beta-8 (beta-Tub8) and Unk1 genes under abiotic stresses. However, IDE and Act11 were indicated as the best combination of reference genes for biotic stress analysis, whereas the Skip16 and Act11 genes were the best combination to study abiotic stress. These genes should be useful in the normalization of gene expression by RT-PCR analysis in common bean, the most important edible legume.

Endophytic fungi from the Amazonian plant Paullinia cupana and from Olea europaea isolated using cassava as an alternative starch media source

Endophytic fungi live inside plants, apparently do not cause any harm to their hosts and may play important roles in defense and growth promotion. Fungal growth is a routine practice at microbiological laboratories, and the Potato Dextrose Agar (PDA) is the most frequently used medium because it is a rich source of starch. However, the production of potatoes in some regions of the world can be costly. Aiming the development of a new medium source to tropical countries, in the present study, we used leaves from the guarana (a tropical plant from the Amazon region) and the olive (which grows in subtropical and temperate regions) to isolate endophytic fungi using PDA and Manihot Dextrose Agar (MDA). Cassava (Manihot esculenta) was evaluated as a substitute starch source. For guarana, the endophytic incidence (EI) was 90% and 98% on PDA and MDA media, respectively, and 65% and 70% for olive, respectively. The fungal isolates were sequenced using the ITS- rDNA region. The fungal identification demonstrated that the isolates varied according to the host plant and media source. In the guarana plant, 13 fungal genera were found using MDA and six were found using PDA. In the olive plant, six genera were obtained using PDA and 4 were obtained using MDA. The multivariate analysis results demonstrated the highest fungal diversity from guarana when using MDA medium. Interestingly, some genera were isolated from one specific host or in one specific media, suggesting the importance of these two factors in fungal isolation specificity. Thus, this study indicated that cassava is a feasible starch source that could serve as a potential alternative medium to potato medium.