Influence of leucite content on slow crack growth of dental porcelains

Objectives. To determine the stress corrosion susceptibility coefficient, n, of seven dental porcelains (A: Ceramco I; B: Ceramco-II; C: Ceramco-III; D: d.Sign; E: Cerabien; F: Vitadur-Alpha; and G: Ultropaline) after aging in air or artificial saliva, and correlate results with leucite content (LC). Methods. Bars were fired according to manufacturers` instructions and polished before induction of cracks by a Vickers indenter (19.6 N, 20 s). Four specimens were stored in air/room temperature, and three in saliva/37 degrees C. Five indentations were made per specimen and crack lengths measured at the following times: similar to 0; 1; 3; 10; 30; 100; 300; 1000 and 3000 h. The stress corrosion coefficient n was calculated by linear regression analysis after plotting crack length as a function of time, considering that the slope of the curve was (2/(3n + 2)]. Microstructural analysis was performed to determine LC. Results. LC of the porcelains were 22% (A and B); 6% (C); 15% (D); 0% (E and F); and 13% (G). Except for porcelains A and D, all materials showed a decrease in their n values when stored in artificial saliva. However, the decrease was more pronounced for porcelains B, F, and G. Ranking of materials varied according to storage media (in air, porcelain G showed higher n compared to A, while in saliva both showed similar coefficients). No correlation was found between n values and LC in air or saliva. Significance. Storage media influenced the n value obtained for most of the materials. LC did not affect resistance to slow crack growth regardless of the test environment. (c) 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Influence of pH on slow crack growth of dental porcelains

Objectives. To evaluate the effect of pH of storage medium on slow crack growth (SCG) parameters of dental porcelains. Methods. Two porcelains were selected: with (UD) and without (VM7) leucite particles, in order to assess if the microstructure would affect the response of the material to the pH variation. Disc specimens were produced following manufacturers` instructions. Specimens were stored in artificial saliva in pHs 3.5, 7.0 or 10.0 for 10 days and after that the fatigue parameters (n: SCG susceptibility coefficient and sigma(0): scaling parameter) were obtained by the dynamic fatigue test using the same pH of storage. Microstructural analysis of the materials was also performed. Results. For VM7, the values of n obtained in the different pHs were similar and varied from 29.9 to 31.2. The sigma(0) value obtained in pH 7.0 for VM7 was higher than that obtained in the other pHs, which were similar. For porcelain UD, n values obtained in pHs 7.0 and 10.0 were similar (40.8 and 39.6, respectively), and higher than that obtained in pH 3.5 (26.5). With respect to sigma(0), the value obtained for porcelain UD in pH 10.0 was lower than those obtained in pHs 3.5 and 7.0, which were similar. Significance. The effect of pH on the stress corrosion susceptibility (n) depended on the porcelain studied. While the n value of VM7 was not affected by the pH, UD presented lower n value in acid pH. For both porcelains, storage in acid or basic pH resulted in strength degradation. (C) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Crack detection in hollow section structures through coupled response measurements

Detection of a circumferential crack in a hollow section beam is investigated using coupled response measurements. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. This matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. The suitability of the mode coupling methodology is first demonstrated analytically. Laboratory test results are then presented for circular hollow section beams with artificially generated cracks of varying severity. It is shown that this method has the potential as a damage detection tool for mechanical structures. (C) 2002 Elsevier Science Ltd. All rights reserved.

O Branqueamento de capitais e a droga

Mestrado em Contabilidade

Perfil sociodemográfico e de padrões de uso entre dependentes de cocaína hospitalizados

OBJETIVO: Avaliar o perfil sociodemográfico e o padrão de uso da cocaína entre usuários de drogas hospitalizados. MÉTODOS: Estudo transversal com dependentes químicos maiores de 18 anos, internados em alguns hospitais psiquiátricos da região metropolitana da Grande São Paulo, Brasil, com condições clínicas de responder a questionário padronizado e que concordaram em participar do estudo. Foram selecionados seis hospitais psiquiátricos que recebiam, por procura espontânea, pacientes da rede pública e privada de toda a região da Grande São Paulo. A coleta de informações foi feita por meio de entrevistas estruturadas, aplicada individualmente por psicóloga treinada. Para análise estatística utilizou-se do teste t de Sudent e Qui-quadrado, e o nível de significância foi fixado em 5%. RESULTADOS: Encontrou-se maior taxa (38,4%) de usuários de crack e pequena prevalência (1,6%) de usuários de drogas injetáveis. Os dependentes de cocaína fumada apresentavam baixa escolaridade, encontravam-se mais freqüentemente desempregados, haviam morado nas ruas, usavam maiores quantidades de droga e tinham sido presos em maior número de vezes do que aqueles que usavam outras vias de administração da droga. CONCLUSÕES: Os resultados sugerem que o uso de drogas é um grave problema de saúde pública na Grande São Paulo, mostrado pelo número de internações hospitalares por dependência. Os usuários de crack apresentam pior condição socioeconômica e maior envolvimento com a violência e a criminalidade.

Caracterização da cultura de crack na cidade de São Paulo: padrão de uso controlado

OBJETIVO: Caracterizar a situação do uso de crack na cidade de São Paulo, assim como o perfil sociodemográfico de seu usuário. PROCEDIMENTOS METODOLÓGICOS: Estudo qualitativo etnográfico com amostra intencional de usuários (n=45) e ex-usuários de crack (n=17). Os participantes foram recrutados pela técnica de amostragem em cadeias e responderam a uma entrevista semi-estruturada, direcionada por questionário, durante os anos de 2004 e 2005. O conjunto de cada questão e suas respectivas respostas originou relatórios específicos que foram interpretados individualmente. ANÁLISE DOS RESULTADOS: O perfil predominante do usuário de crack foi ser homem, jovem, solteiro, de baixa classe socioeconômica, baixo nível de escolaridade e sem vínculos empregatícios formais. O padrão de uso mais freqüentemente citado foi o compulsivo, caracterizado pelo uso múltiplo de drogas e desenvolvimento de atividades ilícitas em troca de crack ou dinheiro. Entretanto, identificou-se o uso controlado que consiste no uso não-diário de crack, mediado por fatores individuais, desenvolvidos intuitivamente pelo usuário e semelhantes, em natureza, às estratégias adotadas por ex-usuários para o alcance do estado de abstinência. CONCLUSÕES: A cultura do uso de crack tem sofrido mudanças quanto ao padrão de uso. Embora a maioria dos usuários o faça de forma compulsiva, observou-se a existência do uso controlado, que merece maior detalhamento, principalmente quanto às estratégias adotadas para seu alcance.

HIV/AIDS risk among female sex workers who use crack in Southern Brazil

OBJECTIVE: To understand the social context of female sex workers who use crack and its impact on HIV/AIDS risk behaviors. METHODODOLOGICAL PROCEDURES: Qualitative study carried out in Foz do Iguaçu, Southern Brazil, in 2003. Twenty-six in-depth interviews and two focus groups were carried out with female commercial sex workers who frequently use crack. In-depth interviews with health providers, community leaders and public policy managers, as well as field observations were also conducted. Transcript data was entered into Atlas.ti software and grounded theory methodology was used to analyze the data and develop a conceptual model as a result of this study. ANALYSIS OF RESULTS: Female sex workers who use crack had low self-perceived HIV risk in spite of being engaged in risky behaviors (e.g. unprotected sex with multiple partners). Physical and sexual violence among clients, occasional and stable partners was widespread jeopardizing negotiation and consistent condom use. According to health providers, community leaders and public policy managers, several female sex workers who use crack are homeless or live in slums, and rarely have access to health services, voluntary counseling and testing, social support, pre-natal and reproductive care. CONCLUSIONS: Female sex workers who use crack experience a plethora of health and social problems, which apparently affect their risks for HIV infection. Low-threshold, user-friendly and gender-tailored interventions should be implemented, in order to increase the access to health and social-support services among this population. Those initiatives might also increase their access to reproductive health in general, and to preventive strategies focusing on HIV/AIDS and other sexually transmitted infections.

Futuros sobre a margem operacional da refinação do petróleo bruto: crack spreads

Mestrado em Contabilidade Internacional

Evolução do consumo de crack em coorte com histórico de tratamento

OBJETIVO: Analisar a evolução do consumo entre usuários de crack com histórico de tratamento. MÉTODOS: Uma coorte de, originalmente, 131 dependentes de crack admitidos em uma enfermaria de desintoxicação em São Paulo, SP, entre 1992 e 1994, foi re-entrevistada em três ocasiões: 1995-1996, 1998-1999 e 2005-2006. As variáveis averiguadas foram: dados demográficos, comportamento sexual de risco, padrões de consumo de crack e outras substâncias, prisões, desaparecimentos e óbitos. Na análise estatística empregou-se o teste de qui-quadrado, a regressão logística multinomial e regressão de Cox. RESULTADOS: Dos pacientes avaliados, 43 estavam abstinentes do crack (12 meses ou mais), 22 eram usuários, 13 estavam presos, dois desaparecidos e 27 estavam mortos. Foram identificados três grupos com trajetórias distintas de consumo pós-alta. Comportamento seguro com uso de preservativo foi identificado como fator relacionado ao grupo de abstinentes estáveis (p = 0,001). Teste HIV positivo na internação (p = 0,046); consumo de cocaína aspirada no último ano (p = 0,001) e tempo de uso de cocaína aspirada na vida (mais de 132 meses) (p = 0,000) foram fatores relacionados a uso de longo termo. Uso pregresso de cocaína endovenosa aumentou em 2,5 vezes as chances de óbito em 12 anos (p = 0,031) (IC95%: 1,08; 5,79). CONCLUSÕES: A recorrência e persistência do consumo nos anos pós-alta de tratamento refletem novas modalidades de uso do crack. Por outro lado, padrões de abstinência estável apontam a viabilidade dos processos de recuperação relativos ao uso de crack.

Mode III interlaminar fracture of carbon/epoxy laminates using the edge crack torsion (ECT) test

The mode III interlaminar fracture of carbon/epoxy laminates was evaluated with the edge crack torsion (ECT) test. Three-dimensional finite element analyses were performed in order to select two specimen geometries and an experimental data reduction scheme. Test results showed considerable non-linearity before the maximum load point and a significant R-curve effect. These features prevented an accurate definition of the initiation point. Nevertheless, analyses of non-linearity zones showed two likely initiation points corresponding to GIIIc values between 850 and 1100 J/m2 for both specimen geometries. Although any of these values is realistic, the range is too broad, thus showing the limitations of the ECT test and the need for further research.

Festa e droga: circustâncias dos consumos de substâncias psícoactivas ilícitas na população portuguesa

Parece à primeira vista contraditório estabelecer uma conjunção entre a festa e a droga que o discurso cultural tradicional avaliam de forma bem diferente, pelo menos se associarmos as drogas às substâncias consideradas mais perigosas, potencialmente e, por isso, classificadas como sendo ilícitas. A associação já pareceria perfeitamente aceitável se por "drogas" nos referíssemos ao tabaco mas, sobretudo ao álcool. Festa, digna desse nome, como qualquer celebração, inclui sempre um momento para o brinde, que não se faz sem "um copo", desde o copo de "vinho doce", guardado no armário das nossas infâncias, na expectativa de qualquer bom acontecimento - que muitas vezes tardava - até ao copo de cidra - "sem álcool" - com o qual se socializam os nossos filhos à estéfica da festa, passando pelo "copo" que é, ele mesmo, o pretexto para a "festa". Drogas ilícitas, no entanto, estão mais conotadas com o risco, com a desgraça-que-se-espera-nunca-bata-à-nossa- -porta, com a miséria... No plano do discurso institucional, a droga aparece também conotada negativamente, primeiro, através da figura da delinqüência, presente já na ilegalidade do acto que o consumo representa e, em seguida, considerando as circunstâncias que acompanham a aquisição da substância, depois através da figura da doença, que acabou por se impor ulfimamente.

ASSOCIATION BETWEEN SMOKING, CRACK COCAINE ABUSE AND THE DISCONTINUATION OF COMBINATION ANTIRETROVIRAL THERAPY IN RECIFE, PERNAMBUCO, BRAZIL

Despite the effectiveness of combination antiretroviral therapy in the treatment of people living with HIV/AIDS (PLWHA), nonadherence to medication has become a major threat to its effectiveness. This study aimed to estimate the prevalence of self-reported irregular use of antiretroviral therapy and the factors associated with such an irregularity in PLWHA. A cross-sectional study of PLWHA who attended two referral centers in the city of Recife, in Northeastern Brazil, between June 2007 and October 2009 was carried out. The study analyzed socioeconomic factors, social service support and personal habits associated with nonadherence to antiretroviral therapy, adjusted by multivariable logistic regression analysis. The prevalence of PLWHA who reported irregular use of combination antiretroviral therapy (cART) was 25.7%. In the final multivariate model, the irregular use of cART was associated with the following variables: being aged less than 40 years (OR = 1.66, 95%-CI: 1.29-2.13), current smokers (OR = 1.76, 95%-CI: 1.31-2.37) or former smokers (OR = 1.43, 95%-CI: 1.05-1.95), and crack cocaine users (OR = 2.79, 95%-CI: 1.24-6.32). Special measures should be directed towards each of the following groups: individuals aged less than 40 years, smokers, former smokers and crack cocaine users. Measures for giving up smoking and crack cocaine should be incorporated into HIV-control programs in order to promote greater adherence to antiretroviral drugs and thus improve the quality of life and prolong life expectancy.

A model to simulate the moment-rotation and crack width of FRC members reinforced with longitudinal bars

The present work describes a model for the determination of the moment–rotation relationship of a cross section of fiber reinforced concrete (FRC) elements that also include longitudinal bars for the flexural reinforcement (R/FRC). Since a stress–crack width relationship (σ–w)(σ–w) is used to model the post-cracking behavior of a FRC, the σ–w directly obtained from tensile tests, or derived from inverse analysis applied to the results obtained in three-point notched beam bending tests, can be adopted in this approach. For a more realistic assessment of the crack opening, a bond stress versus slip relationship is assumed to simulate the bond between longitudinal bars and surrounding FRC. To simulate the compression behavior of the FRC, a shear friction model is adopted based on the physical interpretation of the post-peak compression softening behavior registered in experimental tests. By allowing the formation of a compressive FRC wedge delimited by shear band zones, the concept of concrete crushing failure mode in beams failing in bending is reinterpreted. By using the moment–rotation relationship, an algorithm was developed to determine the force–deflection response of statically determinate R/FRC elements. The model is described in detail and its good predictive performance is demonstrated by using available experimental data. Parametric studies were executed to evidence the influence of relevant parameters of the model on the serviceability and ultimate design conditions of R/FRC elements failing in bending.