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O assentamento passivo tem sido considerado um dos mais importantes requisitos para o sucesso de próteses implanto-suportada. Este estudo in vitro investigou a deformação do intermediário de prótese implantosuportada após o aperto do parafuso tanto do cilindro de Paládio-Prata como de Cobalto-Cromo. Um modelo mestre foi usado para simular uma mandíbula humana com cinco implantes. Extensômetros foram colados nas faces mesial e distal de cada intermediário para registrar as deformações causadas pelos cilindros após o aperto dos parafusos. Os intermediários foram montados sobre as réplicas dos implantes e os parafusos foram apertados com um torque de 20 Ncm e as leituras foram gravadas. Após este passo, os parafusos tanto dos cilindros de Paládio-Prata como de Cobalto-Cromo foram apertados com um torque de 10 Ncm e as leituras também foram gravadas. Estas medições foram repetidas por cinco vezes. O teste estatístico de Mann-Whitney foi aplicado aos resultados. Nenhuma diferença estatística foi encontrada entre as tensões geradas tanto pelos cilindros de Paládio-Prata como os de Cobalto-Cromo. No entanto, existiram diferenças com relação à qualidade da tensão. A deformação gerada pelo aperto dos parafusos dos cilindros de Cobalto-Cromo foi de compressão e o aperto dos parafusos dos cilindros de Paládio-Prata gerou forças de compressão e tração. / Passive fit has been considered one of the most important requirements for the success of implant supported prostheses. This in vitro study investigated the abutment deformation of an implant-supported prosthesis after screw tightening of palladium-silver and cobalt-chromium prosthetic cylinder. A master model was used to simulate a human mandible with five implants. The Strain gauges were attached on the sides of each abutment to capture deformations because of the cylinders screws after was tightened. The abutments were mounted onto implant replicas and the screws were tightened to a 20 Ncm torque, and the readings were recorded. After this step, palladiumsilver and cobalt-chromium prosthetic cylinders were tightened to a 10 Ncm torque and the readings were recorded. The measurements were repeated five times. Mann-Whitney statistical test was applied to the results. No statistical differences were found between the deformation generated by palladium-silver and cobalt-chromium prosthetic cylinders. However, there were differences relative to the quality of the strain. The deformation generated by screw tightness of the cobalt-chromium prosthetic cylinders was compressive while palladium-silver prosthetic cylinders generated compressive and tensile strain.

Research in the area of juvenile delinquency indicates that a high percentage of juvenile offenders have social-emotional problems. According to Agnew's General Strain Theory, negative emotional responses result from juvenile offenders who experience certain strains that he or she dislikes and these emotional responses may create pressure for the juvenile offender to respond through criminal acts. Although some study results suggest that negative emotional responses may mediate the effects of strain on delinquency, other studies have found them to be unrelated. The purpose of the current study was to examine if a juvenile offender's negative, internalizing problems such as depression and anxiety play a mediating role between measures of school and family strain and his or her total number of offenses. Participants consisted of 79 detained youth from a short-term detention center in the U.S. Southwest. There were 91% male and 9% female participants, with an age range of 11 to 17 years of age. The study consisted of 53.2% Latino(a), 25.3% White, 8.9% multiracial, 5.1% African American, 3.8% Native American, and 1.3% Vietnamese. Results from hierarchical multiple regression analyses indicated that school strain and a composite measure of strain were significantly associated with total number of offenses. School strain was significantly associated with depressive and anxious symptoms. Family strain and the composite measure of strain were only significantly associated with depressive symptoms. No significant association was found between the internalizing problems of depression and anxiety and total number of offenses. Therefore, depression and anxiety did not mediate the role between the measures of school and family strain and total number of offenses. Implications of these findings, as well as limitations and areas of future research are also discussed.

Working below the threshold limit value (TLV) for heat stress is not always feasible. When work above the TLV is required, an exposure method is needed that can help protect workers from time limiting heat stress by calculating a safe time for work at certain heat exposures. The purpose of this paper is to determine whether the USARIEM Heat Strain Decision Aid (HSDA) can be used to predict time limiting heat stress exposure in an occupational setting. Twelve adults participated in time limited heat stress exposures. A range of heat stress conditions were designed using three different ensembles and five different heat stress levels. Safe exposure times were assigned based on limiting criteria for core temperature (38.5°C), high heart rate (90% of age-estimated maximum), or willingness to continue. The HSDA process was adapted to an Excel function using Visual Basic for Applications (VBA) and trial data were input data to the HSDA function. A second HSDA function was used to find a predicted core temperature for fixed a standard person using a height of 170cm, a weight of 70kg, and an initial core temperature of 37°C. The logistic regression and probability of the individual data as well as the fixed data were compared. We found that the HSDA could be used to assess time limiting exposures in an occupational setting when workers are working above the TLV.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14836号 / 工博第3133号 / 新制||工||1469(附属図書館) / 27242 / UT51-2009-F478 / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 小寺 秀俊, 教授 北條 正樹, 教授 田畑 修 / 学位規則第4条第1項該当

>Magister Scientiae - MSc / This research project had two different parts: The first was about the mapping of a section of the Warm Zand Structure and the collection of strain data. The second part focused on the analysis of the finite strain and strain pattern in the Warm Zand Structure. The Warm Zand Structure consists of strongly deformed calc-silicates of the Puntsit formation and feldpathic quarzites of the Goede Hoop formation which gradually change into pure quartzites in some locations. The second phase of folding F2 in the calc-silicates gave open folds. Strain markers are very scarce in the Warm Zand Structure; on the Emmanuel Farm pebbles were not found. However on the Compion Farm, pebbles are scattered and occur in few number. In the study area boudins were found in loose rocks hence they could not be used to estimate orientation of the XY plane of the strain ellipsoid (Ramsay, 1967). Folds on the other hand was common and was used to investigate the bulk shortening of the rocks and to understand the kinematical folding mechanisms involved in the folding process of the rock in the Warm Zand Structure. The strain contour map and the Sherwin and Chapple graph were used to investigate the strain and viscosity contrast respectively. The viscosity contrast of the folds collected in the Puntsit falls between 100-53 whereas the bulk shortening on the other hand is between 60-53%. The values of the shortening found agree with those found by van Bever Donker (1980). The numerical modelling on the other demonstrated that in addition to layer parallel shortening and the flattening mention by van Bever Donker (1980) Tangential Longitudinal Strain and Flexural Flow are also involved in the folding process of the fold collected in the Puntsit Formation.

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The measurement of strain is critical in many engineering design, test, and health monitoring procedures. Despite the promise of non-contacting and remote strain measurement, optical techniques have not been widely adopted by industry; the preference being the use of electrical resistance strain gauges. This is due to the perceived and real complexities of many optical techniques.

Particulate, discrete and frictional systems such as sand constitute a separate class of materials. In order to derive stress-strain relations for these materials, their key features have to be identified and incorporated into the theoretical formulations. The presence of voids, the ability to undergo continuous and systematic spatial rearrangement of particles, the existence of bounds for the developed ratio of tangent and normal contact forces and the systematic variations of the tangent and normal contact force distributions during general loading, are identified as key features of particulate, discrete and frictional systems. The contact normal and the contact branch length distribution functions describe the spatial arrangement of particles mathematically. The distribution of contact normals exhibit mutually orthogonal principal directions which coincide with the principal stress directions. Most contacts in frictional systems do not develop limiting friction during general loading. Sliding of a few suitably oriented contacts followed by rolling and rigid body rotations and displacements of a large number of particles is the main mechanism causing non-recoverable deformations in frictional systems. As a part of the rearranging process, dominant chains of particles are continuously constructed and destructed, the rates being different at different stages of loading. A change of loading direction is associated with a change of dominant chains of particles resulting in changes in strain magnitudes. Rate insensitive incremental stress-strain relations are derived here using the principle of virtual forces. The key features of frictional systems have been incorporated into the stress-strain relations following the theoretical framework proposed by Rothenburg(1980), for analysing bonded systems of uniform spherical particles. For frictional systems, the load-deformation response at particle contacts is assumed to be non-linear. The deformations resulting from all internal activity are quantified defining equivalent incrementally elastic stiffnesses in the tangent and normal directions at contacts and defining loading and unloading criteria. After each increment of loading, the incremental stiffnesses and contact normal distribution are updated to account for the changes resulting from rearrangement of particles. Laws that describe the spatial rearrangement of particles, changes in the ratio between the tangent and normal contact force distributions and the resistance to deformation resulting from changes in dominant chains of particles are established based on the information from laboratory experiments reported in the literature and numerical experiments of Bathurst(1985). The stress ratio and the state parameter (defined as the ratio of void ratios at the critical-state to the current state, computed for a given mean-normal stress) are identified as key variables that can be used to quantify the extent of particle rearrangements. The proposed formulations are capable of modelling the non-linear stress-strain response which is dependent on the inherent anisotropy, stress induced anisotropy, density of packing, stress level and stress path. To predict the stress-strain response of sand, a total of 24 model parameters have to be evaluated. All the model parameters can be evaluated from five conventional triaxial compression tests. The proposed stress-strain relations have been verified by comparing with laboratory measurements on sand. The data base consists of triaxial tests reported by Negussey(1984), hollow cylinder tests graciously carried out for the author by A. Sayao, and true triaxial and hollow cylinder tests made available for the Cleveland Workshop(1987). / Applied Science, Faculty of / Civil Engineering, Department of / Graduate