A 3D generalized rigid particle contact model for rock fracture

Detailed rigid particle models have been proposed for modeling fracture in quasibrittle materials. The rigid particle circular models proposed in the literature do not properly reproduce the known rock friction angle and the observed rock tensile strength to compression strength ratio. In this article, a 3D rigid particle contact model, 3D-GCM, is presented which has been developed to study fracture phenomena in rock. The 3D-GCM contact model incorporates in a straightforward manner the force versus displacement relationships of the traditional contact point contact model model, PCM. Furthermore it provides both moment transmission and simple physical constitutive models based on standard force displacement relationships. The 3D-GCM model is validated against known triaxial and Brazilian tests of a granite rock. It is shown that the enhanced rigid particle model leads to a better agreement with the experimental results

VGCM3D - a 3D rigid particle model for rock fracture following the voronoi tessellation of the grain structure: formulation and validation

Detailed particle models by taking into account the material grain structure explicitly consider the material randomness, including a size limiter for damage localization. A VGMC3D contact model is presented that considers the polyhedral particle shape in an approximate way. The VGCM3D flexible contact model is validated against known experimental data on a granite rock, namely triaxial tests and Brazilian tests

Identification of cell-surface mannans in a virulent Helicobacter pylori strain

With the intent of contributing to a carbohydrate-based vaccine against the gastroduodenal pathogen, Helicobacter pylori, we report here the structure of cell-surface mannans obtained from a virulent strain. Unlike other wild-type strains, this strain was found to express in good quantities this polysaccharide in vitro. Structural analysis revealed a branched mannan formed by a backbone of α-(1→6)-linked mannopyranosyl residues with approximately 80% branching at the O-2 position. The branches were composed of O-2-linked Man residues in both α- and β-configurations: (image) In addition, this strain also expressed cell-surface emblematic H. pylori lipopolysaccharides (LPS) containing partially fucosylated polyLacNAc O-chains. Affinity assays with polymyxin-B and concanavalin A revealed no association between the mannan and the LPS. The described mannans may be implicated in the mediation of host–microbial interactions and immunological modulation.This work was supported by Fundacao para a Ciencia e Tecnologia (FCT) through project Pylori E&LPS POCI/QUI/56393/2004, PhD grant SFRH/BD/19929/2004, by the Natural Sciences and Engineering Research Council of Canada (NSERC), and by the European Network of Research Infrastructures within the 6th Framework Programme of the EC (Contract # RII3-026145, EU-NMR). The authors further thank Dr. Adrien Favier (RALF-NMR facility, Grenoble - France) for conducting NMR experiments

Amniocentesis in a tertiary referral centre: still the same old story?

Overview and Aims: The main objective of this study was to describe the main clinical indications, diagnostic yield, complications and pregnancy outcomes regarding amniocentesis performed in a tertiary University Hospital, during an 8-year period. Study Design: We developed an observational, retrospective study, of all amniocenteses performed between June 2003 and June 2011. Population: All pregnant women consecutively submitted to amniocentesis in a tertiary University Hospital between June 2003 and June 2011. Only singleton gestations were included. Methods: We searched the database of the Genetics Department for all products obtained by invasive procedures performed during pregnancy between June 2003 and June 2011, in order to identify the amniocenteses performed during that period. Maternal demographics, indication for amniocentesis, gestational age at the time of amniocentesis, procedure-related complications during pregnancy and pregnancy outcome data were extracted from patient's physical and electronic medical records. Results: A total of 1358 amniocenteses were included in the study. The proportion of amniocentesis performed due to maternal age decreased significantly and due to positive prenatal screening significantly increased over time (p<0,001).The indication with highest positive predictive value regarding abnormal fetal karyotype was parent carrier of chromosome abnormality (46.2%). Total pregnancy loss was 1.6%, post-procedural miscarriage rate was 0.74% and fetal loss risk within 2-weeks of procedure was 0.4%. There was no association between fetal loss and operator, number of needle insertions, transplacental puncture and bloody tap. Conclusions: Counselling is complex and questions regarding procedure-related complications and fetal loss have been inconsistently reported. National and local institutional precise estimates are important to consider when advising women requesting amniocentesis

Bioaccumulation of amylose-like glycans by Helicobacter pylori

Background: Helicobacter pylori cell surface is composed of lipopolysaccharides (LPSs) yielding structures homologous to mammalian Lewis O-chains blood group antigens. These structures are key mediators in the definition of host-microbial interactions and known to change their expression pattern in response to environmental pressure. Aims:  The present work is focused on the identification of new H. pylori cell-surface glycosides. Special attention is further devoted to provide insights on the impact of in vitro subcultivation on H. pylori cell-surface phenotypes. Methods:  Cell-surface glycans from H. pylori NCTC 11637 and two clinical isolates were recovered from the aqueous phase resulting from phenol:water extraction of intact bacteria. They were evaluated in relation to their sugars and glycosidic-linkages composition by CG-MS, size-exclusion chromatography, NMR, and Mass Spectrometry. H. pylori glycan profile was also monitored during subcultivation in vitro in agar and F12 liquid medium. Results:  All three studied strains produce LPS expressing Lewis epitopes and express bioaccumulate amylose-like glycans. Bioaccumulation of amylose was found to be enhanced with the subcultivation of the bacterium on agar medium and accompanied by a decrease in the expression of LPS O-chains. In contrast, during exponential growth in F12 liquid medium, an opposite behavior is observed, that is, there is an increase in the overall amount of LPS and decrease in amylose content. Conclusions:  This work shows that under specific environmental conditions, H. pylori expresses a phase-variable cell-surface α-(1→4)-glucose moiety

3D Voronoi Tessellation for the Study of Mechanical Behavior of Rocks at Different Scales

Numerical investigation of crack damage development and microfracturing in brittle rocks is a widely studied topic, given the number of applications involved. In the framework of the Discrete Element Method (DEM) formulation, the grain-based distinct element model with random polygonal blocks can represent an alternative to the Bonded-Particle Model (BPM) based on particles. Recently, a new engine called Neper has been made available for generating 3D Voronoi grains. The aim of this study is to investigate the applicability of a Neper-based 3D Voronoi tessellation technique for the simulation of the mechanical macro response of rocks. Simulation of unconfined compression tests on synthetic specimens is conducted and a calibration procedure tested. The issue related to scale effects is also addressed, with an application to the case study of a deep geothermal reservoir

Origem, formação e conservação do gado Pé-Duro, o bovino do Nordeste brasileiro.

O gado Pé-Duro constitui recurso genético de grande importância a ser preservado, apresentando elevada rusticidade, com capacidade de produtividade sob condições consideradas críticas para sobrevivência. Além da rusticidade, prolificidade e habilidade materna, características altamente desejáveis, apresenta ainda carne de melhor qualidade, com grau de maciez superior ao dos gado Zebu. Desta forma, esses animais precisam ser multiplicados, avaliados e difundidos em programas de melhoramento genético, visando-se o aproveitamento das suas qualidades para utilização e inserção nos diversos sistemas de produção. Apesar da grande adaptação ao Semiárido brasileiro, o gado Pé-Duro tem sua sobrevivência prejudicada em decorrência dos cruzamentos desordenados a que foi e continua sendo submetido. A introdução das raças zebuínas no Brasil, mais produtivas, porém mais exigentes por alimentação e manejo, tem constituído ameaça ao gado Pé-Duro. Nos sistemas de cruzamentos usados atualmente, a obtenção de animais com maior vigor híibrido tem sido erroneamente atribuída apenas à introdução do sangue zebu, enquanto a contribuição do pé-duro tem sido depreciada. Este trabalho objetiva resgatar a história da raça e fornecer subsídios, regras básicas e estabelecer critérios para a conservação do bovino da raça Pé-Duro, valioso recurso genético em risco de extinção.bitstream/item/83449/1/Doc-208-Origem-Gado-Pe-Duro.pd

Condições de vida e vocabulário receptivo em crianças de dois a cinco anos

OBJECTIVE: To assess the receptive vocabulary of children aged between two years and six months and five years and eleven months who were attending childcare centers and kindergarten schools. METHODS: An analytical cross-sectional study was carried out in the municipality of Embu, Southeastern Brazil. The Peabody Picture Vocabulary Test and analysis of factors associated with children's performance were applied. The sample consisted of 201 children of both genders, aged between two and six years. Statistical analysis was performed using multivariate analysis and logistic regression model. The dependent variable analyzed was test performance and the independent variables were child's age, mother's level of education and family socio-demographic characteristics. RESULTS: It was observed that 44.3% of the children had performances in the test that were below what would be expected for their age. The factors associated with the best performances in the test were child's age (OR=2.4; 95% CI: 1.6-3.5) and mother's education level (OR= 3.2; 95% CI: 1.3-7.4). CONCLUSIONS: Mother's education level is important for child's language development. Settings such as childcare and kindergarten schools are protective factors for child development in families of low income and education.OBJETIVO: Avaliar o vocabulário receptivo de crianças de dois anos e seis meses a cinco anos e 11 meses que freqüentam creches e pré-escolas. MÉTODOS: Estudo transversal e analítico realizado no município de Embu, Estado de São Paulo. Utilizou-se o Teste de Vocabulário por Imagem Peabody e análise de fatores associados ao desempenho. A amostra foi constituída de 201 crianças de ambos os sexos, com idade entre dois e seis anos. Foram realizados análise multivariada e modelo de regressão logística. A variável dependente analisada foi o desempenho no teste e as variáveis independentes foram a idade da criança, tempo de escolaridade e série, e características sociodemográficas de suas famílias. RESULTADOS: Observou-se que 44,3% das crianças apresentaram desempenho inferior ao esperado para a idade no teste e os fatores associados ao melhor desempenho foram a idade da criança (OR=2,4; IC 95%: 1,6-3,5) e a escolaridade materna (OR=3,2; IC 95%: 1,3-7,4). CONCLUSÕES: A escolaridade maternal é importante no desenvolvimento de linguagem da criança. As instituições como creches e pré- escolas são fatores de proteção do desenvolvimento infantil em famílias de baixa renda e com baixa escolaridade.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de FonoaudiologiaUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de PediatriaUNIFESP, EPM, Depto. de FonoaudiologiaUNIFESP, EPM, Depto. de PediatriaSciEL