Opening-mode fractures—joints and veins—are widespread structures in sedimentary rocks even in slightly deformed and flat-lying sequences. Understanding the growth and connectivity of fractures in low permeability sandstone reservoirs is essential for optimal hydrocarbon exploitation. In a linear elastic fracture mechanics framework, it is generally assumed that fractures widen in aperture while they propagate in length or height. However, it is also conceivable that a phase of proportional aperture to length or height growth is followed by a phase of aperture growth with relatively slow or arrested tip propagation. Slow propagation relative to aperture opening can occur by non-elastic deformation processes or if the material elastic properties change over time. Fracture propagation in length or height can be halted by material strength heterogeneities. To test for concurrent length versus aperture growth of these fractures, I reconstructed the crack-seal opening history for multiple cement bridges sampled at different distances from the tip of three opening-mode fractures in Travis Peak Sandstone of the SFOT-1 well, East Texas. Crack-seal cement bridges have been interpreted to form by repeated incremental fracture opening and subsequent precipitation of quartz cement that bridges the fractures. Crack-seal cement textures were imaged using a scanning electron microscope with a cathodoluminescence detector, and the number and thickness of crack-seal cement increments determined. Trends in crack-seal increments number and thickness are consistent with fast initial fracture propagation relative to aperture growth, followed by a stage of slow propagation and pronounced aperture growth. Cumulative fracture opening displacement based on palinspastic reconstruction of two cement bridges was compared to analytical solutions for a stationary and a propagating fracture aperture as a function of position relative to the fracture tip in an elastic medium. Based on this comparison, I conclude that the crack-seal cement record reflects largely the phase of dominant aperture growth and subcritical fracture propagation under constant loading stress. / text

Few studies have reported the incidence or prevalence of cracked teeth with pulpal involvement. No attempts have been made to evaluate the prevalence or clinical predictors for intrapulpal cracks. The purpose of this study was to investigate the prevalence of intrapulpal cracks in first and second mandibular molars and to determine if clinical findings are predictive for the existence of intrapulpal cracks. First and second mandibular molars (190) requiring non-surgical root canal treatment at the VCU Graduate Endodontic Practice between February 15, 2013 and August 15, 2013 were analyzed retrospectively. Teeth were transilluminated, stained, and inspected for intrapulpal cracks using a dental microscope. Data gathered included: demographics, subjective and objective information regarding the chief complaint to include bite stick test, transillumination, probing depths greater than 4mm, existing restorations, and diagnosis. Chi-square and logistic regression were performed (p<0.05). The prevalence of intrapulpal cracks in first and second mandibular molars combined was 9% (17/190, 95%CI= 5.7% to 13.9%). The prevalence was 7% for 1st molars and 13% for 2nd molars. There was no statically significant difference in the prevalence between first and second mandibular molars. Individual characteristics predictive for the existence of intrapulpal cracks were age, probing depth greater than 4mm, transillumination and a positive Tooth Slooth™ test (all p<0.05). Staining of the pulp chamber after access identified only one of 17 intrapulpal cracks. Staining of the pulp chamber did not significantly increase the ability to identify intrapulpal cracks. Neither diagnosis, sex, nor existing restorations were significant predictors for intrapulpal cracks. Probing depth greater than 4mm, age over 40 and a positive Tooth Slooth™ test were conjointly significant for predicting intrapulpal cracks.

Cracked teeth may be difficult to diagnose. Craze lines rarely become symptomatic or require treatment. Cracks in the enamel and dentin alone may or may not become symptomatic and require restorative treatment. However, cracks extending into the enamel, dentin, and pulp chamber provide an avenue for bacteria to establish infection and this commonly results in symptoms and the need for endodontic and restorative treatment. The published endodontic literature has limited information regarding the prevalence or predictive factors for cracks extending into the pulp chamber of teeth. The purpose of this study was to determine the prevalence and classification of intrapulpal cracks in maxillary premolars and to identify factors that may aid in diagnosing the existence and extent of a crack. The cracks were classified according to the Intrapulpal Crack Classification System proposed by Detar in 2014. All maxillary premolar teeth treatment planned for non-surgical root canal therapy (NSRCT) or retreatment (RETX) at Virginia Commonwealth University (VCU) Graduate Endodontic Practice from January 2014 through February 2015 were included in the study after obtaining patient consent. Teeth were examined visually, stained, and examined microscopically for the presence of an intrapulpal crack. Demographic information, subjective data associated with the chief complaint, objective results of diagnostic testing (percussion, palpation, bite stick test, transillumination, probing depths), existing restorations, pulpal diagnosis, and periapical diagnosis were analyzed using chi-square and multiple logistic regression (P

Master of Science / Department of Mechanical and Nuclear Engineering / Kevin Lease / Over the past several years the crack tip opening angle (CTOA) has been identified as one of the key fracture parameters to characterize low constraint stable tearing and instability in structural metallic alloys. This document presents the results of experimental stable tearing characterizations. Characterization methods include optical microscopy and marker band measurements of crack front tunneling. Specific attention is given to the measurement methods used, and also the correlation between CTOA and Delta-5. The effect of tunneling and comparisons with computational results are discussed, and the effect of material and measurement method on CTOA is observed and a clear relationship is seen. Preliminary work on future studies into internal features and behavior is also presented.

Doctor of Philosophy / Department of Civil Engineering / Robert J. Peterman / This dissertation describes a testing program to evaluate the bond and splitting propensity characteristics of 5.32-mm-diameter prestressing wires. Prestressing wire reinforcement is used primarily in the production of prestressed concrete railroad ties. Twelve different 5.32-mm-diameter wires were tested in this study in order to measure bonding characteristics of the reinforcement. Establishment of the bond-slip characteristics of these reinforcement at both transfer of prestress (transfer bond) and under flexural loading (flexural bond) is necessary to enable the accurate modeling of these ties using finite elements. Transfer bond and flexure bond of various indent patterns were tested using tensioned pullouts. Specimens of various sizes with single or multiple wires were tested to determine the effects of cover and wire number on bond. Indents were machined on smooth prestressing wires to accurately compare indent geometries. Lateral expansion was tested to determine which wires have higher propensity to cause cracking or splitting. Crossties were instrumented to compare resulting lateral expansion with results found in the laboratory. The results from the testing program showed that the tensioned pullout test was able to be used to predict the transfer length of prisms made with the same reinforcement. The results also showed that the indent geometries were able to be used to predict the splitting of specimens based on the amount of slip the wire had experienced. The testing also showed the importance of concrete cover with the relation to splitting potential.

O presente trabalho analisa o impacto do exercício da repressão penal sobre os usuários de crack na busca pelo tratamento, avaliando a coerência entre os fins declarados pela atual política de drogas e os meios previstos em lei para sua consecução. O estudo se desenvolveu por meio de pesquisa qualitativa com seres humanos operada através de entrevistas com usuários e ex-usuários de crack em tratamento, bem como com os profissionais da equipe multidisciplinar do local de tratamento. / This paper analyzes the impact of criminal repression on crack users seeking treatment, evaluating the coherence between the purposes declared by the current drug policy and the means provided by law for its achievement. This paper was conducted by means of a qualitative research with humans beings, operated through interviews with crack users and former users in treatment, as well as with professionals in the multidisciplinary team from the treatment site.

Submitted by PPG Psicologia (psicologia-pg@pucrs.br) on 2018-03-21T13:20:05Z No. of bitstreams: 1 TES_BRENO_SANVICENTE_VIEIRA.pdf: 6222146 bytes, checksum: d1e5e710fc5ec0e52c03bb4ffe92d0f8 (MD5) / Approved for entry into archive by Tatiana Lopes (tatiana.lopes@pucrs.br) on 2018-04-03T20:11:47Z (GMT) No. of bitstreams: 1 TES_BRENO_SANVICENTE_VIEIRA.pdf: 6222146 bytes, checksum: d1e5e710fc5ec0e52c03bb4ffe92d0f8 (MD5) / Made available in DSpace on 2018-04-03T20:22:52Z (GMT). No. of bitstreams: 1 TES_BRENO_SANVICENTE_VIEIRA.pdf: 6222146 bytes, checksum: d1e5e710fc5ec0e52c03bb4ffe92d0f8 (MD5) Previous issue date: 2018-03-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / In Brazil, 1.4% of the population reports lifetime use of smoked cocaine (crack). The use of the drug relates to social and economic issues for society and poses serious health problems, including early death. Crack cocaine use disorder (CUD) is the medical condition which refers the pathological use of the drug. CUD relates to several negative outcomes such as higher rates of HIV and HCV infections, familiar problems and crime involvement, in addition to a higher prevalence of concurrent mental disorders. Scientific agendas promote evidence-based studies as a need for better therapeutics. In this regard, some gaps in the field require attention. In this line, distinct factors confer vulnerability for crack cocaine use in males and females: more males use the drug (a 3:1 proportion), but females show a faster transition from initial drug use to CUD. The course of the disease also show differences; females report a higher craving for the drug, while males have more frequent involvement with violent crimes. Thus, scientific commitments highlight a calling for the integration of those biopsychosocial models that consider individual characteristics in addition to those who consider addictive disorders as ?brain diseases.? A more consistent interdisciplinary integration of knowledge from classical theories in combination with advances provided for technologic methods is a promising route. Hence, the aim of this doctoral thesis was to investigate sex differences in crack cocaine users. To address the main objective, the thesis has two studies with groups of participants diagnosed with CUD and hospitalized for drug detoxification. These two groups were one of males (CK-M) and a second of females (CK-F). Study 1 had as its objective to get a picture of sex differences in the psychosocial profile. Study 2 had as its objective the identification of sex differences in brain functioning level. Study 1 had 798 CK-M and 546 CK-F. Results consistently revealed CK-M as having a more severe alcohol use history and higher rates of concurrent alcohol use disorder than CK-F. On the other hand, CK-F showed an earlier crack cocaine use onset, higher drug use severity, and more familiar and work problems along with a higher prevalence for lifetime mental disorders. Particularly, CK-F showed higher rates for trauma and stress. Study 2 had a sample of 80 participants: CK-M (n = 20), CK-F (n = 20), a group of males (HC-M, n = 20), and another of healthy female controls (HC-F, n = 20). Participants did a resting-state functional magnetic resonance imaging (rs-fMRI) scan. The method makes it possible to investigate temporal associations between nonspatially related brain areas by using as a measure fluctuations in the blood oxygen-level dependent (BOLD) level. It is an indirect measure of energy consumption, and by testing those correlations, functional connectivity (FC) can be investigated. Results supported CK-M as having an overall higher intra- and internetwork FC, while CK-F showed an overall lower FC in this regard. Taking both studies, the conclusions of this thesis point toward the existence of sex differences in all biopsychosocial domains. Thus, the interpretation of studies in crack cocaine use, particularly those testing interventions, need to resemble the possible existence of sex differences. Therefore, a hope from studies like this is that sex-specific models for crack cocaine use and CUD emerge and become tested. Similarly, possible interventions, also need to be aware of such backgrounds and consider possible sex differences when developing interventions, researches and public health policies as well. / No Brasil, cerca de 1.4% da popula??o refere j? ter feito uso de coca?na atrav?s de sua forma fumada (crack). O uso da droga gera repercuss?es sociais e econ?micas para a sociedade, al?m de ser um grave problema de sa?de relacionado, inclusive, com a morte precoce. Considerando o Transtorno por Uso de Coca?na (TUC) a manifesta??o patol?gica relacionada ao uso da droga, alguns dos desfechos desfavor?veis incluem: maiores taxas de infec??o por HIV e HCV; problemas judiciais e familiares, al?m maior preval?ncia de transtornos mentais em comorbidade. Iniciativas cient?ficas estimulam que propostas baseadas em evid?ncias sejam realizadas na tentativa de melhores resultados para o tratamento e preven??o do TUC. Neste sentido, maiores aprofundamentos em lacunas do conhecimento na ?rea s?o importantes. Assim, homens e mulheres possuem fatores de vulnerabilidade ao uso da droga distintos: Mais homens usam coca?na (propor??o de 3:1), mas mulheres apresentam uma evolu??o mais r?pida ao TUC ap?s o in?cio do uso. O curso da doen?a tamb?m ? diferente, mulheres sentem mais fissura pela droga, enquanto homens tem mais consequ?ncias relacionadas a crimes violentos. Assim sendo, iniciativas cient?ficas destacam a necessidade de integra??o de modelos biopsicossociais, que levem em conta as caracter?sticas individuais, mas que tamb?m considerem transtornos aditivos ?doen?as do c?rebro?, favorecendo a interdisciplinaridade entre antigas e robustas bases te?ricas e avan?os tecnol?gicos. Neste sentido, o objetivo desta tese foi investigar diferen?as entre homens e mulheres usu?rios de crack. Para tanto, dois estudos foram realizados com grupos de portadores de TUC internados para desintoxica??o do uso de crack, tendo sempre um grupo de homens (TUC-H) e outro de mulheres (TUC-M). No Estudo 1, o objetivo foi tra?ar um claro perfil de diferen?as psicossociais e de gravidade do uso de drogas, enquanto no Estudo 2 o objetivo foi identificar a exist?ncia de diferen?as em um n?vel de funcionamento cerebral. O Estudo 1 teve 798 TUC-H e 546 TUC-M. Resultados identificaram robustas diferen?as, com TUC-H possuindo uma hist?ria mais grave de uso de ?lcool, bem como uma maior preval?ncia para o transtorno por uso de ?lcool. Em contrapartida, TUC-M apresentam uma idade mais precoce do in?cio do uso de crack, maior severidade do uso de drogas em geral, preju?zos mais significativos nas esferas de trabalho e fam?lia, al?m taxas mais altas de preval?ncia de transtornos mentais (em especial transtornos relacionados a trauma e estresse). No Estudo 2, com 80 participantes al?m dos grupos TUC-H (n = 20) e TUC-M (n=20), participaram 20 homens saud?veis e 20 mulheres saud?veis. O m?todo utilizado foi um exame de Resson?ncia Magn?tica funcional (fMRI) em estado de repouso (rs-fMRI). Rs-fMRI permite avaliar associa??es na flutua??o do sinal BOLD (blood oxygen-level dependente, do ingl?s n?vel dependente de oxig?nio no sangue), que ? uma medida indireta de consumo energ?tico, entre ?reas cerebrais anatomicamente distintas, o que ? aceito como um dado de conectividade funcional (CF). Os resultados indicaram que de maneira geral, TUC-H apresentam um aumento na CF entre diferentes redes cerebrais, enquanto TUC-F apresentam redu??o na CF. Com base nos resultados, a tese conclui que homens e mulheres usu?rios de crack apresentam diferen?as em caracter?sticas que permeiam todos os dom?nios biopsicossociais, o que deve ser considerado ao levar em conta interpreta??es de estudos na ?rea e, principalmente, ao planejarem-se poss?veis interven??es no futuro. Portanto, espera-se que modelos sexo-espec?ficos para o uso de coca?na e do TUC sejam formulados, bem como que interven??es, pesquisas e inclusive pol?ticas de sa?de p?blica considerem poss?veis diferen?as em suas fundamenta??es.

O consumo de crack é um dos grandes desafios em saúde pública e o uso desta droga tem efeitos diretos na saúde de seus usuários. Objetivos: Identificar o perfil dos pacientes em tratamento para a dependência química de crack no Centro de Atenção Psicossocial para Álcool e Drogas (CAPS-AD III) em Palmas - TO, bem como seus possíveis efeitos vasculares periféricos. Métodos: Trata-se de um estudo observacional, descritivo, de corte transversal. Os pacientes da amostra foram submetidos a um questionário objetivo avaliando questões demográficas, padrão de uso da droga, coexistência de diabetes mellitus, hipertensão arterial ou tabagismo, além de exame físico e ecográfico. Os dados foram sumarizados e analisados estatisticamente com teste Qui-quadrado ou Exato de Fisher. O nível de significância estabelecido foi de 5% (p<0,05). Resultados: A média de idade dos 58 indivíduos da amostra foi de 33,29 (±7,15) anos, sendo quase 74% do gênero masculino. A média de idade de início de uso da droga foi de 23,4 (±7,78) anos, com tempo médio de uso de 9,58 (±5,64) anos. O consumo médio de pedras de crack foi de 21,45 (±8,32) pedras, com uma frequência média semanal de uso da droga de 5,74 (±1,81) dias. A alteração de pulsos em membros inferiores foi prevalente em mulheres. A prevalência do espessamento da parede arterial dos membros inferiores foi de 94,8%. O tempo de uso da droga apresentou associação estatística (p=0,0096) com alteração do padrão de curva espectral das artérias dos membros inferiores. Conclusões: O tempo de uso da droga foi o fator mais importante e com maior impacto no sistema vascular periférico, sugerindo associação entre o uso do crack e a diminuição de fluxo arterial nos membros inferiores. / The crack consumption is a major challenge in public health and the use of this drug has direct effects on the health of its users. Objectives: To identify the profile of patients in treatment for drug addiction crack at the Psychosocial Care Center for Alcohol and Drugs (CAPS-AD III) in Palmas - TO, as well as if it’s possible peripheral vascular effects. Methods: This is an observational cross-sectional study. Patients were submitted to an objective questionnaire assessing demographic issues, standard of drug use, diabetes mellitus coexistence, high blood pressure or smoking, and physical and ultrassonography examination. Data were summarized and statistically analyzed with chi-square or Fisher's exact test. The significance level was 5% (p <0.05). Results: The mean age of the 58 subjects of the sample was 33.29 (± 7.15) years, and almost 74% were male. The average age of onset of drug use was 23.4 (± 7.78) years, with an average usage time of 9.58 (± 5.64) years. The average consumption of crack was 21.45 (± 8.32) stones, with an average weekly frequency of drug use of 5.74 (± 1.81) days. Alteration pulses in the lower limbs was prevalent in women. The prevalence of arterial wall thickening of the lower limbs was 94.8%. The drug usage time presented statistical association (p = 0.0096) with altered spectral curve pattern of lower limb arteries. Conclusions: The time of drug use was the most important factor and with greater impact on the peripheral vascular system, suggesting an association between crack use and the reduction of blood flow in the lower limbs.

This thesis concerns crack growth phenomena in rubber. It is widely known that a relationship exists between the magnitude of the stored energy release rate available to drive a crack, called the tearing energy (7'), and the resultant crack growth rate. For rubbers this basic relationship is said to be a characteristic of the material. The magnitude of T is related to both the visco-elastic losses and the crack tip diameter (d) However the actual size of d and its relationship with the viscoelastic losses is not clear. This thesis examines the crack growth behaviour in relation to d and the visco-elastic losses for a wide range of rubbers, whose visco-elastic properties are altered either by swelling in a liquid, altering the test temperature or the cross-link density and by the incorporation of fillers. Static, constant T, crack growth tests were carried out. These revealed that two different crack growth processes exist. For the fast crack growth process, T is determined by variations in the visco-elastic losses alone. For the slow crack growth process, T is determined by variations in both the visco-elastic losses and d. It is proposed here that the factors, which alter d, are associated with cavitation ahead of the crack tip for unfilled materials and with strength anisotropy for carbon black filled materials. In cyclic crack growth tests, the crack growth per cycle, dc/dn, can be considered to result from the sum of time and cyclic dependent crack growth components. For the first time, the detailed magnitudes of the contribution of each of these components to dc/dn have been determined, for a wide range of materials and mechanisms responsible for this behaviour are postulated. Also crack growth tests, both static and cyclic, were extended to very large extensions. Lastly this investigation revealed that the tensile strength for both ciystallising and noncrystallising rubber can be predicted using the tearing energy concept for a variety of loading regimes.

In the past, the use of a fracture mechanics approach to describe crack growth in elastomers has been shown to work well for specimens of simple test geometry, simply loaded. This has been the case because elastic strain energy density (e.s.e.d.) functions could reliably be used to calculate both the magnitude of elastic stored energy available to drive a crack and the magnitude of the rate of release of such energy as the crack grows. The aim of this thesis was to investigate the applicability of such a methodology to situations of more complex loading. To this end two novel test-piece geometries were developed. The first consisted of a pure shear geometry with the sample having been pre-strained in the longitudinal direction to varying extents, hence introducing a type of bi-axial deformation. The second consisted of a pure shear geometry test-piece inclined at 30° to the horizontal and loaded in the vertical direction, hence inducing simultaneously pure shear and simple shear loading. Both types of test-piece were used to study the validity of the particular e.s.e.d. functions, the energetics and mechanics of crack growth and crack growth geometries on a macro and micro scale. The constants in particular e.s.e.d. functions were determined by uniaxially deforming in pure shear each of the carbon black reinforced materials used in this study. The resulting functions became progressively less good at predicting the elastic strain energy in the novel geometry test-pieces as the deformation modes became more complex. Anisotropy induced by deforming specimens in one direction was not easily removed even by an imposed large deformation in another direction. Nevertheless, the functions were successfully used to predict crack growth directions in the 30° inclined test-piece. However in the pre-strain pure shear test-pieces the functions significantly underestimated the elastic strain energy. Hence the real energies had to be determined from the forces and extensions measured during cyclic crack growth tests. In these tests crack growth rates for a given tearing energy (elastic energy release rate) increased as the magnitude of the pre-strain increased. This significant weakening was associated with the development of a strain induced molecular and carbon black anisotropy.