Introdução: Na atualidade, o uso abusivo de drogas vem tomando dimensões preocupantes, configurando um importante problema de saúde pública. Dentre os aspectos responsáveis pelo agravamento da situação está o surgimento de novas substâncias, as quais vêm alterando as práticas de uso e potencializando seus danos. Dentre elas o derivado da pasta de coca, denominado popularmente de crack, destaca-se pelos prejuízos à saúde dos usuários e devido à associação crescente entre sua utilização e a prática de atos violentos e degradantes, especialmente difundida pelos meios de comunicação. Objetivos: Descrever os circuitos, compreender comportamentos, práticas e significados relacionados ao consumo de crack entre freqüentadores de locais de alta concentração de usuários e vendedores desta droga instalados na região central de duas capitais brasileiras: São Paulo/SP e Porto Alegre/RS. Metodologia: Foi realizado um estudo etnográfico, com observação participante e registro em diário de campo. Resultados: Nos resultados foram descritos os circuitos percorridos pelos usuários, concentrados em partes específicas da região central das duas cidades: Bairro da Luz/SP e nas imediações do Loteamento Santa Terezinha em Porto Alegre/RS, assim como suas dinâmicas, nas quais a concentração de pessoas em situação de rua e suas atividades rotineiras, principalmente em suas interrelações com representantes do poder público, como a polícia e instituições de assistência social, ganham destaque. O cotidiano desses locais caracteriza-se por relações tensas e freqüentes conflitos entre os diferentes atores participantes dos circuitos Pelas características dos contextos de pesquisa, a grande maioria dos usuários apresentava um padrão de uso compulsivo de drogas, especialmente de crack, no qual o auto-cuidado ou quaisquer outras atividades eram secundarizadas frente ao consumo frenético da droga. Apesar disto, identificou-se sujeitos que não apresentavam este padrão de uso, empregando diversas estratégias de autocontrole na administração da droga e também de sobrevivência. Conclusão: Aponta-se a importância de observar elementos como a história da região pesquisada, políticas públicas, questões econômicas e ausência de investimentos sociais e em saúde pública para a compreensão da instalação e permanência dos circuitos pesquisados. Sugere-se que o alto grau de degradação daquelas regiões não seria decorrência apenas das pessoas e atividades exercidas no local, mas principalmente do processo urbano que gerou tal quadro social. Além disso, aponta-se para uma estreita relação entre o contexto sócio-histórico-cultural dos sujeitos e seu padrão de uso de crack, indicando a existência de diferenças internas ao grupo estudado que caracterizam usuários com um mínimo de organização estrutural e ética daqueles para os quais a obtenção e consumo do crack adquire primazia frente às demais atividades e relações de seu cotidiano / Introduction: In current days, drug abuse has been acquiring alarming dimensions, configuring an important problem of public health. Among the factors which are responsible for the worsening of the situation is the appearance of new substances which have been altering the practices of use and potentiating its damages. Among these is the product of cocaine paste, popularly called crack, which characterizes by the harm to the users health and a growing association between its use and the practice of violent and degrading acts, which has been given a lot of attention by the media. Objectives: To describe the circuits, understand the behaviors, the practices and the meanings related to crack consumption among goers of places of high concentration of users and sellers of this drug, in the downtown area of two Brazilian capitals: São Paulo/SP and Porto Alegre/RS. Methodology: A qualitative-ethnographic study was undertaken, with participant observation and register in field journal, having these as a basis for data analysis. Results: In the results, the circuits taken by the users concentrated in specific parts of the central area of both cities were described: Bairro da Luz, in São Paulo, and the region between Rodovia Castelo Branco, Avenida Farrapos and Loteamento Santa Terezinha in Porto Alegre/RS. And also its dynamics: the concentration of people living in the street and their routine activities, specially their relations with state representatives (such as the police and social assistance institutions) are highlighted. The everyday routine of these places is characterized by tense relations and frequent conflicts among the different actors in interaction. According to the research context, most users presented a pattern of compulsive use, in which self-care or any other activities were in second place in relation to the frenetic drug use. However, some subjects who didnt present this use or dependency pattern were identified, employing several strategies of self-control in the use of the drug and also regarding survival. Conclusion: We point to the importance of observing factors such as the history of the researched region, public policies, economic issues, and the absence of social and public health investments for the understanding of the appearance and permanence of the researched circuits. We suggest that the high degree of degradation of those regions wouldnt be a consequence only of the people and activities performed in the place, but mostly, of the urban process that generated such social frame. We also point to a strict relation between the socio-cultural-historical context of the subjects and their crack consumption pattern, indicating the existence of internal differences in the studied group, which distinguishes users with a minimal degree of structural and ethical organization from those for whom the obtaining and consumption of crack acquires priority regarding any other activities or relations of their daily life

A presente pesquisa tem como objetivo reconstruir os acontecimentos em torno da Operação Integrada Centro Legal (mais conhecida como Operação Sufoco), deflagrada na região central de São Paulo conhecida como cracolândia, em janeiro de 2012. Trata-se de uma intervenção policial que parece evidenciar o que todo um campo de pesquisas vem flagrando em outras cidades do Brasil e do mundo como uma lógica securitária nas formas de gestão e produção do espaço urbano. Além disso, dentro do contexto da cracolândia, essa operação pode ser tida como um ponto de virada na forma como o Estado intervém atualmente nesse território, que passou a ser foco de políticas das três esferas de governo nos últimos três anos. A hipótese que orienta a análise da operação, seus efeitos e a configuração atual da região da cracolândia é a de que as inovações nas formas de gerir esse território observadas recentemente podem ser entendidas tendo como referência as limitações e resistências geradas pelos campos de disputa que surgiram em torno desta ação policial. A partir da análise da atuação judicial de defensores e promotores públicos com vistas a fazer cessar a operação na região, são apresentados neste trabalho alguns dos conflitos e disputas que se processaram em torno da \"cracolândia\" e das formas de gerir esse espaço, por exemplo, sobre qual o papel que as forças repressivas deveriam ter (ou não) no trato da questão do crack, o embate entre o direito de ir, vir e permanecer dos usuários de cracke o direito à segurança, e as disputas entre diferentes saberes médicos sobre as formas de tratamento de usuários e dependentes químicos. Nesse sentido, a cracolândia, a Operação Sufoco e toda a reconfiguração que ela engendrou nesse território foram escolhidos como cenas privilegiadas para observar as conflituosidades que esse tipo de intervenção securitária engendra e como tais disputas influenciam na dinâmica reconfiguração dos dispositivos de controle que visam garantir a ordem nesse espaço urbano. / This research aims to reconstruct the events around the \"Operação Integrada Centro Legal\" (known as Operation Suffocation), deflagrated in the central region of São Paulocityknown as \"crackland\" in January 2012. This is a policeintervention thatseems to evidencewhatawhole field of research is capturingin other cities in Brazil and in the world as a security-logic in the forms of managing and producing urban space. In addition, within the context of \"crackland\", this operation can be seen as a turning point in the way the state currently intervenes in that territory, which became the focus of policies of the three levels of government in the last three years. The hypothesis that guides the analysis of this intervention, its effects and the current setting of \"crackland\" region is that innovations in ways of managing this territory recently observed can be understood with reference to the limitations and resistance generated by the fields of dispute that emerged around this police operation. From the analysis of the judicial action of public defenders and prosecutors in order to end the operation in the region, some of the conflicts and disputes about \"crackland\" and ways to manage this spaceare presented in this work, e.g on what role the repressive forces should (or should not) have at the crackissue, the battlebetween thecrackusers\'right to go, come and stay versusthe right to security, and disputes between different medical knowledge on ways to treat users and addicts. In this sense, \"crackland\", \"Operation Suffocation\" and all reconfiguration itengendered in that territory were chosen as privileged scenes to observe the conflictsthat this type of security-intervention engenders and how these disputes influencein the dynamic reconfiguration of control devices that aim to ensure order in this urban space.

A adição de diferentes substâncias (adulterantes e diluentes) no crack (freebase) é um fenômeno bem conhecido no mercado ilícito. Os adulterantes podem interagir com a cocaína e determinar novas e desconhecidas síndromes tóxicas influindo no estado clínico das intoxicações, especialmente em casos em que houve modificação das vias de administração. No Brasil a análise de adulterantes, contaminantes e/ou diluentes adicionados ao crack não constitui rotina nos laboratórios oficiais. Nesse contexto, o presente trabalho pretendeu a caracterização de um grupo de amostras de crack que fornecerá informações na investigação sobre o narcotráfico, no estudo da morbi-letalidade, bem como na toxicovigilância. O método utilizado neste trabalho foi realizado com a técnica de cromatografia gasosa acoplada a detector em ionização de chamas CG-DIC. Os resultados obtidos nas análises de amostras provenientes de apreensões realizadas na região metropolitana de São Paulo num período de 20 meses, no período de março de 2008 a novembro de 2009, mostraram que 9,16% das amostras continham lidocaína, benzocaína e cafeína como adulterantes e 14,57% continham outros adulterantes totalizando 23,73%. O percentual em teor médio de cocaína presentes nas amostras de crack foi de 71,3%. Adicionalmente foram avaliadas as propriedades organolépticas. O resultado das análises das amostras estudadas mostrou maior teor de cocaína em relação à cocaína comercializada na forma de sal (cloridrato ou sulfato) comercializado como \"droga de rua\" no Estado de São Paulo. Ainda, os interferentes e adulterantes encontrados nas amostras estudadas permitem a inferência do importante problema de saúde pública advindos do uso dessa droga. / The addition of different substances (contaminants and fillers) in the crack (freebase) is a well known phenomenon in the illicit market. The contaminants can interact with cocaine and identify new and unknown toxic syndromes influencing the clinical state of intoxication, especially in cases where there was a modification of the routes. In Brazil, the analysis of adulterants, contaminants and / or extenders added to the crack is not routine in official laboratories. In this context, this work aims to characterize a sample group of crack that provides information on an investigation into drug trafficking in the study of morbidity and mortality, as well as toxicological. The method used in this study utilized the technique of gas chromatography coupled with flame ionization detector GC-FID. The analysis results of samples from seizures made in the metropolitan region of Sao Paulo in a period of 20 months, from March 2008 to November 2009 showed that 9.16% of the samples contained lidocaine, benzocaine, and caffeine as adulterants and 14.57% contained other adulterants totaling 23.73%. The average content in percentage of cocaine present in the samples of crack was 71.3%. Additionally, we evaluated the organoleptic properties of the row samples. The results of analysis of the samples tested showed higher levels of cocaine in the cocaine sold in the form of salt (hydrochloride or sulfate) marketed as \"street drug\" in the State of São Paulo. Still, the interferences and adulterants found in the samples studied allow the inference of important public health problem arising from the use of this drug.

In an attempt to find a way of improving the damage tolerance of composite bonded repairs to metallic aircraft structures, the effect of using conventional crack growth retardation techniques in conjunction with bonded repairs was experimentally investigated. Hence, an experimental test program was set up to determine whether fatigue crack growth under bonded repairs is retarded further by giving the crack to be repaired a crack growth retardation treatment prior to repair patch application. In addition, it was set up to determine the influence of a bonded repair on the effectiveness of a crack growth retardation method. Centrally cracked aluminium plates were used. Stop drilling followed by cold hole expansion and the application of single overloads were selected as retardation treatments. Two patch materials were considered; boron/epoxy and Glare 2. Further test variables were the aluminium alloy and the plate thickness. Fatigue testing was carried out under constant amplitude loading and baseline results were determined first. In addition to optically monitoring the crack growth, local and global out-of-plane deformations were visualised with holographic interferometry and shadow moire??. Furthermore, the stress intensity factors under the repair patch were examined with strain gauges and measurement of the central crack opening displacement. Disbonds and fracture surfaces were studied after residual strength tests. The crack growth results obtained showed that retardation treatments decrease crack growth rates under a repair patch and that the effectiveness of a retardation treatment is increased by the patch. Although identical crack growth rates were observed under boron/epoxy and Glare 2 patches, the reinitiation period after the retardation treatment lasted longer when Glare 2 patches were applied. Analytical predictions of the extent of retardation based on existing models showed that the conjunctive effect of retardation treatments and bonded repairs was underestimated. A sustained reduction in crack growth rates was observed under bonded repairs with a prior overload retardation treatment. It was concluded that the damage tolerance of bonded repairs is increased by the application of a crack growth retardation treatment because the crack growth is retarded further. These findings indicate that the range of cracks in aircraft for which bonded repairs can be considered is expanded and that economic benefits can be obtained.

Fatigue assessments have been carried out predominantly with quasi-deterministic approaches, such as the use of SN curves. However, both the loading and the resistance of fatigue prone components are subjected to significant uncertainties. Consequently, a prediction of the remaining fatigue life based on deterministic load and resistance models can lead to unreliable results. This work presents a general reliability-based approach to predict fatigue life of steel components. The approach incorporates prediction of fatigue crack initiation, modeled with a strain-based correlation approach, and propagation, modeled using a linear elastic fracture mechanics approach, and is applicable to new, cracked or repaired structural components. Based on the analysis of existing test results and additional crack initiation and propagation tests on weld metal, the relevant probabilistic fatigue material properties of grade 350WT steel and a matching weld metal were established. An experimental program was carried out on welded details tested either in the as-welded, stress-relieved, conventionally peened, or ultrasonically peened condition. It was demonstrated that ultrasonic peening is superior to the other investigated post weld treatment methods. Using finite element analyses, the results of the tests were deterministically predicted for several different initial conditions, including initial flaw and crack sizes and locations, as well as different levels of residual stresses. A model incorporating an initial flaw and accounting for crack closure and the threshold stress intensity factor range was retained. A probabilistic analysis using Monte Carlo Simulation was carried out to calibrate the relevant parameters. A general reliability-based approach, which includes both the loading and resistance sides of the limit state function was proposed and applied to three practical examples: prediction of test results from two test programs and the prediction of the remaining fatigue life of a cracked component as a function of the safety index. These three applications demonstrated that accurate fatigue life predictions targeting a predefined safety index are achieved. / Structural Engineering

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La motivació de la tesis deriva en el interès de la indústria aeronàutica a explotar, per mitjà d'un disseny adaptat, la utilització del gir d'esquerda per protegir els reforços situats davant una esquerda que s'està propagant en la xapa d'una estructura integral. L'objectiu principal és l'avaluació i predicció del gir d'esquerda en situacions de càrrega pròximes a Mode I, proporcionant una eina de modelització i un criteri confident. L'entorn industrial sota el qual s'ha realitzat aquest treball requereix una predicció ràpida del comportament estructural proporcionant informació útil als constructors. Per aquest motiu la predicció del gir d'esquerda s'ha investigat utilitzant la teoria linear elàstica de la mecànica de la fractura (LEFM) i l'anàlisi amb elements finits (FEA).Durant aquest treball s'ha demostrat la importància i necessitat de caracteritzar el camp de tensions a la punta de l'esquerda amb el factor d'intensitat de tensió (SIF) conjuntament amb un segon paràmetre. La tensió uniforme, no singular, normal a la línea de l'esquerda i dependent en la geometria i càrrega de la proveta, es a dir la tensió T, ha estat seleccionada com a segon paràmetre per dur a terme les prediccions del gir d'esquerda.El criteri més desenvolupat per predir el gir d'esquerda en situacions pròximes a Mode I és el proposat per Buczek, Herakovich, Boone et al., anomenat WEFO en la tesis. Aquest combina el criteri de tensió principal màxima amb la tensió T i considera efectes d'anisotropia. LEFM s'ha utilitzat també en la predicció del gir d'esquerda sota càrregues quasi estàtiques controlant en tot moment la plastificació del lligament.En la investigació d'eines de modelització/simulació s'ha tingut en compte les capacitats d'aquestes en el camp de la mecànica de la fractura, de disseny, d'implementació, així com la complexitat d'ús. Tot i que hi ha un gran ventall de Softwares que compleixen els requeriments assenyalats, només aquells que es trobaven a l'abast de l'autor s'han analitzat. StressCheck ha estat escollit com a resultat de la investigació. L'avaluació de la propagació de l'esquerda en provetes compactes en tensió (CT) i en provetes amb dos elements reforçants (2SP) sota els règims de Paris i Forman ha estat satisfactòria.Un pas important ha estat la implementació de la capacitat d'extracció de la tensió T. La demostració de la fiabilitat en el seu càlcul s'ha demostrat mitjançant resultats en la literatura i càlculs analítics en provetes de doble biga en volada (DCB). Un aspecte a tenir en compte és la importància en realitzar anàlisis no linears geomètrics pel càlcul del SIF i la tensió T.Prediccions en la trajectòria de l'esquerda s'han realitzat en base amb els resultats obtinguts en l'estudi de modelització. La millor trajectòria s'ha predit per mitjà del criteri WEFO. No obstant, les diferents trajectòries obtingudes per una esquerda propagant-se en la direcció T-L o L-T no són comparables amb els resultats experimentals.Aquestes deficiències estan relacionades en la definició del punt d'inestabilitat de l'esquerda. Algunes referències posen de manifest que hi ha experiències on l'esquerda es comporta de forma estable tot i mostrar T > 0. Per un altre banda, els criteris WEF i WEFO defineixen la inestabilitat dependent d'una distancia específica del material, rc. Però la seva definició no és única i no existeix cap acord sobre el seu càlcul.L'autor proposa un criteri derivat dels criteris existents i basant-se en els assajos, simulacions i resultats obtinguts. Aquest deriva del treball de Pettit i la tensió T normalitzada, TR, proposada per Pook. La fiabilitat d'aquest criteri es demostra amb la proveta DCB. Les prediccions de la trajectòria de l'esquerda en la proveta cruciforme no són tant satisfactòries. Tot i així, s'ha d'accentuar que el criteri desenvolupat proporciona la predicció més acurada. / The motivation of this thesis started from the interest of aeronautical industry to exploit the utilization of crack turning to protect stiffeners in front of an approaching skin-crack in integral structures by a tailored design. The main objective was to assess and predict crack turning under nearly Mode I situations on structures that reproduce aeronautical conditions by providing a modelling tool and a reliable criterion. The industrial environmental in which this work has been carried out requires a fast prediction of the structural behaviour to provide useful inputs to aircraft designers. It is for this reason that the crack turning prediction was investigated by means of LEFM and FEA. During this work it has been shown the importance and necessity of a second parameter for the characterisation of the stress field at the crack tip besides the SIF. Among the different proposed second parameters, the uniform non-singular stress, normal to the crack line and dependent on the type of loading and specimen geometry, i.e. the T-stress, was selected for crack turning predictions due to both calculation simplicity and its independence of the crack tip distance. The most developed criterion for crack turning predictions near Mode I loading is the criterion proposed by Buczek, Herakovich and Boone et al., called the WEFO-criterion. This is the Maximal Principal Stress criterion implemented with the T-stress and taking into account anisotropic effects. A challenge of this thesis was to overcome the lack of prediction on crack turning provided by this last criterion.Although the validity of LEFM is restricted, it was applied for the prediction of crack turning for quasi-static loading while paying attention to possible plastification. A screening of existent commercial and non commercial tools was carried out in respect to their fracture mechanics capabilities, their design abilities, implementation as well as their complexity. Although, there are many software possibilities, only those within the reach of the author were evaluated. This resulted in the selection of the commercial tool StressCheck®. The assessment of crack propagation on compact tension and two stringer specimens governed by the Paris and Forman regimes was satisfactory compared with experimental results using the material data from simple standard specimens.An important step was the implementation of the T-stress extraction facility in the tool and the evidence of its reliability. The latter was proved by literature and analytical calculations on DCB specimens. An important finding was the importance to perform geometric non-linear analyses for computing SIF and T-stress to find values comparable with literature data and analytical calculations. Taking into account the results obtained on the modelling study, crack path predictions were performed. The best prediction by means of existing criteria was reached by the WEFO-criterion. Different crack paths were predicted for a crack propagating in T-L or L-T directions. However, these predictions were not satisfactorily reliable: the point in the crack path where crack turning should take place was not predicted adequately. Additionally, the crack paths were similar for T L and L-T directions. These deficiencies are related with the definition of the crack path instability. Some literature results have shown that in some experiences the crack behaved in a stable manner even if T > 0. Moreover, WEF and WEFO criteria define crack instability to be related with a material specific distance, rc, but, there is no agreement about its definition. Based on tests, simulation results and observations noted during this work, a compilation criterion was proposed. This is based on the work of Pettit and the normalised T-stress, TR, proposed by Pook. Its reliability was successfully proved on the DCB. The crack path predictions on the CFS were not as satisfactory. But even at its worst the developed criterion was the most accurate.