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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

HIP MUSCLE STRENGTH AND PELVIC OBLIQUITY IN COLLEGIATE FEMALES DURING WALKING AND STAIR DESCENT TASKS

Rodriguez, Kelly 01 January 2009 (has links)
The goals of the pelvis include maintaining the center of mass of the body, assisting in foot clearance and absorb forces from the lower extremities using muscles and ligaments to stabilize the joint. A better understanding of the influence of muscle strength on controlling pelvic obliquity in a healthy population will help in understanding low back pain and overuse lower extremity injuries. Thirteen females (22 ±2 yrs) participated in isokinetic strength testing of the hip abductors, adductors, internal rotators and external rotators on a Biodex dynamometer. The subjects also underwent gait analysis during self selected pace walking and stair descent. For each muscle group subjects were divided into weaker and stronger groups based on the mean. Independent t-test revealed a significantly greater amount of pelvic obliquity in the stronger group for abductors, adductors, and internal rotators during stair descent. Subjects may be compensating for more pelvic obliquity with less movement of the hip, knee and ankle. During walking weaker external rotators was the only muscle group that significantly increased pelvic obliquity. Our study supports the finding of other studies that the external rotators contribute to pelvic stabilization during walking (Powers, 2003).
2

An Optimal Interset Rest Period For Strength Recovery During A Common Isokinetic Test

Blazquez, Ivan 16 May 2008 (has links)
Introduction: Isokinetic testing is used in rehabilitation settings on a regular basis, yet there is a lack of consistency in rest period usage among protocols. Purpose: The purpose of this study was to establish an optimal rest period that would allow reproducibility of strength during a common isokinetic strength-test. Methods: Twentyseven healthy college-aged males underwent isokinetic strength testing to determine peak torque at 60, 180 and 300 deg/sec, respectively. Work:rest ratios of 1:3, 1:8 and 1:12 were counterbalanced between sets. A 3 X 3 repeated measures ANOVA was used to analyze the data. The p < .05 level of significance was used for all tests. Results: There was no significant difference in either knee extension or knee flexion peak torque when comparing work:rest ratios. Conclusion: These findings suggest that a 1:3 work:rest ratio is sufficient during a common isokinetic strength test.
3

Mechanical Properties Of A Knee Trochlear Implant

January 2015 (has links)
Focal chondral defects of the knee develop in hyaline cartilage when subjected to repetitive overloading or impact trauma. The degeneration of the articular surface results in joint pain and stiffness during daily activities such as walking. In most cases palliative non-invasive treatments can be used to alleviate pain; however, more severe lesions require restorative or replacement surgical interventions to repair the damaged cartilage. The use of a novel pyrolytic carbon knee trochlear implant aims to eliminate the aforementioned orthopedic pain by providing a focal replacement of lesions in the patellar sulcus. Pyrolytic carbon was the selected material due to its superior wear properties, mechanical strength, and biocompatibility. The purpose of this study was to develop a verified computational simulation in Abaqus to evaluate the experienced tensile stress of six different pyrolytic carbon trochlear implants undergoing two different physiologically relevant load conditions. This data was compared to an experimental conjugate study to provide insight into the implants strength. Regions of peak maximum principal stress were observed to be at the medial fillet and sulcus groove when undergoing a single- or two-point loading condition, respectively. The magnitude of tensile stress in the medial fillet was 2-3 times of that experienced at the sulcus groove. These findings reflected experimental data in which trochlear implants failed at either the medial fillet or sulcus groove during their respective loading conditions. Verified simulations allowed for computational testing of a modified implant and calculations of expected critical fracture loads. / acase@tulane.edu
4

Avaliação da resistência adesiva de três tipos de cimentos resinosos frente à cerâmica a base de dissilicato de lítio / Evaluation of bond strength of three types of resin cements towards the interface of a lithium disilicate ceramic

Manuel Carlos Araújo de Miranda Pinto 04 September 2009 (has links)
O presente estudo hipotetiza que cimentos resinosos com diferentes sistemas de ativação e mecanismo de condicionamento da estrutura dentária, têm a mesma resistência adesiva a uma cerâmica. Objetivos: avaliar a resistência de união de agentes de fixação resinosos, cimento resinoso autopolimerizável (C&B- Bisco), dual (Panavia F- Kuraray) e auto-adesivo (Relyx U-100-3M ESPE) frente a uma cerâmica a base de dissilicato de lítio (IPS Empress-Ivoclar Vivadent). Metodologia: nove blocos de cerâmica e 9 de compósito foram confeccionados com dimensões 6mmx6mmx6mm e fixados por meio de um agente de fixação resinoso (Panavia F, C&B, RelyX U-100). As superfícies da porcelana e do compósito foram tratadas, o sistema adesivo e o agente de fixação resinoso foram aplicados. O bloco de compósito foi posicionado e foi realizada a fotoativação, por quarenta segundos, em cada face dos blocos. Todas as amostras foram armazenadas em água deionizada a 37C por vinte e quatro horas. As amostras foram fixadas às placas de acrílico e seccionadas em uma cortadeira metalográfica. Foram obtidas fatias em forma de palito com 1mm de espessura, num total de 15 por grupo. Decorrido trinta dias foram submetidos ao ensaio de microtração em uma máquina de ensaio universal Kratos e os resultados analisados estatisticamente. O padrão de fratura foi analisado em lupa estereoscópica, classificados quanto ao tipo. Resultados: O cimento de dupla cura (Panavia F) apresentou maior resistência adesiva. O cimento auto-adesivo (Relyx U- 100- 3M ESPE) apresentou adesão inferior aos outros cimentos do estudo. A maioria das fraturas ocorreu dentro da zona adesiva, caracterizando a eficiência e confiabilidade deste teste, na avaliação dos cimentos. Conclusões: O agente de fixação auto-adesivo apresentou adesão inferior aos outros e o cimento dual se apresentou um pouco melhor que o quimicamente ativado. / This study hypothesized that resin cements with different activation modes and mechanisms have the same bond strength towards ceramic interface. Objectives: To evaluate the tensile bond strength of resin-fixing agent, self cured resin cement (C & B, Bisco), dual cement (Panavia, Kuraray) and self-adhesive (Relix U-100) towards the base of a ceramic of lithium disilicate (IPS-Empress Ivoclar Vivadent). Methodology: Nine blocks of ceramics and composite resins were prepared with dimensions 6mmx6mmx6mm. The surface of the porcelain and the composite was treated and the fixing agent (Panavia, C & B, ReLyX U-100), was applied. The composite block was photopolymerized for forty seconds on each side of the block. All samples were stored in deionized water at 37C for twenty-four hours. Afterwards, samples were cut to form matchstick slices 1mm -thick, with a total de 15 per group (n=15). The samples were submitted to microtensile testing at a Kratos universal testing machine (0.05mm/min) and the results were analyzed statistically. The pattern of fracture was observed in stereoscopic and classified. Result: The dual-cure cement (Panavia F) showed higher bond strengths whereas the self-adhesive cement (Relyx U-100) showed the lowest bond strength among groups. Most of the fracture occurred inside the adhesive interface, characterizing the efficiency and reliability of this test in the evaluation of cements. Conclusions: The self-adhesive cement exhibited lower bond strength compared to the other agents. The dual cured cement system presented a slightly better performance than the self-cured cement.
5

Feasibility of Using a Non-Counter Movement Squat to Assess Lower Body Strength in Adults Ages 20-70 years.

January 2019 (has links)
abstract: The purpose of this study was to investigate the Feasibility of Using a Non-Counter Movement Squat to Assess Lower Body Strength in Adults ages 20-70 years. Feasibility was tested by measuring five feasibility metrics described by Bowen et al. (Bowen et al., 2009): Acceptability, Demand, Implementation, Practicality, and Limited Efficacy. Seven male subjects and fifteen female subjects participated in the study. The subjects had their height, weight, body fat percentage by bioelectrical impedance analysis (BIA), and grip strength measured. Subjects performed a warm-up on a cycle ergometer, a Non-Counter Movement Squat Test (NCMST) 1-repetition maximal strength test using a Smith machine, and a cool down on a treadmill. Each subject then completed a post-participation questionnaire used to measure acceptability, Demand was measured by subjects who agreed to participate, implementation was measured by subjects who completed the protocol, practicality was measured by an administrator survey, and limited efficacy was measured by distribution of strength results by age and for all subjects by sex. Results showed acceptance of hypotheses of acceptability, demand, implementation and practicality for both males and females. Limited efficacy was inconclusive for both males and females resulting in rejection of hypothesis. The findings of this study show that further research is needed to compare the NCMST to other lower body muscular strength tests to determine the validity of the NCMST. / Dissertation/Thesis / Masters Thesis Healthcare Innovation 2019
6

Böjhållfasthet i flerskiktad zirkonia före och efter färginfiltrering / Flexural Strength of Multilayered Zirconia Before and After Color Infiltration

Olsson, Elna, Hylén, Vivicka January 2024 (has links)
SAMMANFATTNING  Syfte  Syftet med studien var att undersöka huruvida färginfiltrering med effektfärg påverkar böjhållfastheten i flerskiktad zirkonia.  Material och metod Zirkoniamaterialet KATANA™ Zirconia YML, Kuraray Noritake användes i studien. Totalt framställdes 54 stycken provkroppar varav sex stycken utgjorde en pilotstudie för polering. Resterande 48 delades in i sex grupper (n = 8). Tre av grupperna frästes ut från Emalj och Body 1 (E-B1) och de resterande tre grupperna frästes ut från Body 2 och Body 3 (B2-B3). Två grupper, från de olika skikten, infiltrerades med Esthetic Colorant A plus (A), två grupper infiltrerades med Esthetic Colorant Opaque (O) samt två grupper utgjorde kontrollgrupper utan infiltrering (K). Provkropparna infiltrerades och sintrades enligt fabrikantens anvisningar. Därefter polerades de enligt ett poleringsschema och slutligen genomfördes ett biaxialt böjhållfasthetstest. Resultaten från samtliga grupper analyserades med One-way ANOVA, Tukey’s test, med en signifikansnivå på α = 0,05 med hjälp av statistikprogrammet SPSS.  Resultat Resultatet påvisade ingen signifikant skillnad i böjhållfastheten inom grupperna för de två skikten (E-B1A, E-B1O och E-B1K) samt (B2-B3A, B2-B3O och B2-B3K). Grupperna med skikten som inkluderade B2-B3 uppvisade signifikant högre böjhållfasthet oavsett infiltrering/kontroll än grupperna E-B1A, E-B1O och E-B1K.   Slutsats Böjhållfastheten i flerskiktad zirkonia påverkas inte av infiltrering med effektfärg. / ABSTRACT Purpose The purpose of this in vitro study was to investigate whether color infiltration with effect colors affect the biaxial flexural strength of multilayer zirconia.   Material and method The zirconia material KATANA™ Zirconia YML, Kuraray Noritake was used in the study. A total of 54 specimens were produced, of which six were part of a pilot study for polishing. The remaining 48 were divided into six groups (n=8). Three of the groups were milled of Enamel and Body 1 (E-B1) and the remaining three groups were milled of Body 2 and Body 3 (B2-B3). Two groups, from the different layers, were colored with Esthetic Colorant A plus (A), two groups were colored with Esthetic Colorant Opaque (O), while two groups served as control groups (K). The specimens were colored and sintered according to the manufacturer's instructions, polished according to a polishing schedule, and finally a biaxial flexural strength test was performed. The results were analyzed using One-way ANOVA, Tukey's test, with a significance level of α = 0.05 using the statistical software SPSS.   Results The results showed no significant difference in flexural strength within the groups for the two layers (E-B1A, E-B1O, and E-B1K) and (B2-B3A, B2-B3O, and B2-B3K). The groups with layers that included B2-B3 showed significantly higher flexural strength regardless of coloring/control than the groups E-B1A, E-B1O, and E-B1K.  Conclusion The flexural strength of multilayered zirconia is not affected by color infiltration with effect colors.
7

Výpočet zatížení a pevnostní kontrola křídla kluzáku / Wing Loading Calculation and Stressanalysis of the Glider

Freisleben, Michal January 2009 (has links)
This diploma thesis deals with the calculation of composite wing loading and its stressanalysis. Furthermore work contains design of static strength test wing.
8

Bindningsstyrka mellan protesbas och protestand beroende på framställningsteknik och åldring / Bond strength between Denture Base and Denture Tooth Depending on the Manufacturing Technique and Ageing

Cronberg, Blanka, Rasho, Lina January 2024 (has links)
Sammanfattning Syfte Studiens syfte var att utvärdera bindningsstyrkan mellan protesbas och protestand beroende på framställningsteknik, med 3D-printning eller fräsning, och efter åldring.Material och metodTotalt framställdes 40 provkroppar varav 20 tillverkades genom 3D-printning (P) med SprintRay EU (SprintRay GmbH, Iserlohn, Tyskland) och 20 genom fräsning (F) med Ivotion (Ivoclar Vivadent AG, Schaan, Liechtenstein). Hälften av de frästa (TF) och 3D-printade provkropparna (TP), det vill säga 10 av varje, utsattes för 5 000 termocykler i temperaturerna 5 och 55 °C (T) och förvarades i destillerat vatten i 48 timmar vid en temperatur på 37° C. Bindningsstyrkan mättes genom ett skjuvkrafttest enligt standardiserade metoder.Envägs-ANOVA och Tukey’s test användes för statistisk utvärdering av resultaten där signifikansnivån sattes till α=0,05. En frakturanalys utfördes för att bedöma frakturtyper. Resultat Resultaten visade att P hade en signifikant högre bindningsstyrka än F (p&lt;0,001). Skillnaden kvarstod även efter åldring. Det var ingen signifikant skillnad (p=0,626) i bindningsstyrkan mellan F och TF. TP uppvisade signifikant lägre bindningsstyrka jämfört med P (p=0,007).Alla F fick en adhesiv och kohesiv blandfraktur. P fick nio kohesiva och en adhesiv fraktur. TF fick sex adhesiva och fyra blandfrakturer. TP fick sju kohesiva och tre blandfrakturer. Slutsats 3D-printade material har en högre bindningsstyrka mellan protesbas och protestand jämfört med frästa. Åldring har en större negativ inverkan på bindningsstyrkan mellan protesbas och protestand om materialen är 3D-printade jämfört med om de är frästa. / Abstract Objective The aim of the study was to evaluate the bond strength between denture base and denture tooth depending on the manufacturing technique, fabricated through either 3D-printing or milling, and after ageing.Material and methods40 specimens were produced, 20 were produced through 3D-printing (P) using SprintRay EU (SprintRay GmbH, Iserlohn, Genmany) and 20 through milling (F) using Ivotion (Ivoclar Vivadent AG, Schaan, Liechtenstein). Half of the milled (TF) and printed specimens (TP), i.e., 10 of each group, underwent 5 000 cycles of thermocycling and were stored in distilled water for 48 hours at a controlled temperature of 37° C. Bond strength was evaluated using a shear bond strength test.One-way ANOVA and Tukey’s test were employed to assess the results with a significance level at α=0.05. Fracture analysis was conducted to evaluate the fracture type. Results The result showed that P had significantly higher bond strength compared to F (p &lt;0.001). The difference remained after the ageing process. The comparison between F and TF yielded non-significant results (p=0.626). P had significantly higher bond strength than TP (p=0.007).All F had mixed fractures of adhesive and cohesive. P had nine cohesive and one adhesive fracture. TF had six adhesive fractures and the remaining were mixed fractures. TP had seven cohesive fractures and three mixed fractures. Conclusion 3D-printed materials have higher bond strength between the denture base and denture tooth compared to milled materials. Ageing has a greater negative impact on the bond strength between the denture base and denture tooth of printed materials compared to milled materials.
9

Estudo da influência da variação do teor de umidade no valor do módulo de resiliência de um solo argiloso encontrado em subleito de rodovias no interior paulista / Study of the influence of moisture content in resilient modulus value of a clay found in pavement subgrade in state of São Paulo

Gonçalves, Ricardo Freire 28 June 1999 (has links)
O objetivo deste trabalho é avaliar a influência da variação do teor de umidade no valor do módulo de resiliência (MR) de um solo argiloso de subleito, tendo em vista que este parâmetro é muito susceptível à variações climáticas ambientais. Foram realizados ensaios triaxiais cíclicos para se estimar o módulo de resiliência de corpos de prova ensaiados em diversas condições de umidade. Verificou-se que o MR é influenciado pela tensão desvio, de forma que aquele aumenta com o acréscimo desta. Constatou-se que os corpos de prova moldados na Wot e submetidos a trajetórias de secagem e umedecimento alcançaram valores de MR superiores e inferiores, respectivamente, ao se comparar com o MR de corpos de prova ensaiados na Wot. Este fato foi também observado para os corpos de prova moldados com massa específica seca máxima, em teores de umidade abaixo e acima do teor ótimo. Determinou-se, ainda, a sucção no solo através do método do papel filtro e levantou-se a sua curva característica. Verificou-se que à medida que a umidade aumenta, a sucção diminui. Observou-se que o valor do MR aumenta com o aumento da sucção no solo. Este crescimento é tanto maior quanto maior seja a tensão desvio aplicada. Foi possível determinar a relação entre o MR, a tensão desvio e o módulo tangente inicial (Eo), proveniente dos ensaios de compressão simples. Relacionou-se, também, o Eo e a sucção no solo. / The aim of this work is to evaluate the influence of moisture content variation in resilient modulus value (MR) of a subgrade clayey soil, considering that this parameter is very susceptible to environmental climatic variations. Cyclic triaxial tests were performed to acess resilient modulus of specimens tested in several moisture conditions. lt has been verified that MR is influenced by deviator stress, so that the former increases with the latter increases. lt has been confirmed that specimens molded in Wot and submited to a drying and moistening route reached MR values higher and lower, respectively, to compare with MR of specimens tested in Wot. This fact was also observed for the specimens molded with dry density, in moisture contents below and above of optimum moisture content. lt has been also determined the soil suction using filter paper method and it has been built its characteristic curve. lt has been verified that when moisture increases, the suction decreases. lt has been observed that MR value increases with the soil suction increase. This increase is as bigger as bigger the applied deviator stress be. lt was possible to determine the relationship between MR, deviator stress and parameters from compressive strength tests. lt has been related parameters from compressive strength tests and soil suction.
10

A influência da variação da umidade pós-compactação no comportamento mecânico de solos de rodovias do interior paulista / The influence of post-compaction moisture content variation on the mechanical behavior of soils from São Paulo state pavements

Takeda, Marcelo de Castro 22 May 2006 (has links)
Na construção de rodovias, as condições de umidade e densidade observadas na compactação são, geralmente, próximas daquelas correspondentes ao pico da curva de compactação obtida no ensaio Proctor. É sabido que variações ambientais no decorrer da vida do pavimento podem alterar, de maneira significativa, a umidade do subleito e dos seus componentes e assim, as suas propriedades resilientes. O objetivo principal desta pesquisa é avaliar a influência da variação da umidade pós-compactação no módulo de resiliência de solos de rodovias do interior paulista a partir de resultados de ensaios de laboratório. Foram coletados e caracterizados setenta e três solos, e, dentre estes, selecionados trinta para a etapa de estudo da variação da umidade pós-compactação, após a realização de ensaios MCT, difração de raios-x, microscopia eletrônica de varredura e azul de metileno para determinação da gênese. Os solos selecionados apresentam características distintas quanto à gênese, sendo metade laterítico e metade não-laterítico. Os corpos-de-prova foram compactados na umidade ótima e submetidos a processos de secagem e umedecimento e, posteriormente, realizados ensaios triaxiais cíclicos. Os resultados permitiram a modelagem do 'M IND.R' em função do estado de tensão para diferentes umidades e a avaliação da competência de alguns modelos matemáticos nesta representação. Estudou-se a influência da gênese e da granulometria sobre o valor do 'M IND.R' e avaliou-se a conseqüência da variação da umidade sobre este para solos lateríticos e não-lateríticos. Determinou-se uma expressão para estimar a variação do 'M IND.R' com a variação da umidade a partir do parâmetro k1, independentemente do estado de tensão. Pesquisou-se a existência de relações entre os parâmetros de regressão do modelo composto e os resultados dos ensaios de compressão simples e as propriedades físicas dos solos, de forma a permitir a estimativa do módulo de resiliência a partir do resultado de ensaios mais simples. Investigou-se a possibilidade de se utilizar as relações entre a variação do módulo tangente inicial com a variação da umidade para estimar os efeitos sobre o 'M IND.R'. / On road construction, the field compaction conditions are usually close to those determined from Proctor tests. Environmental variations may lead to changes in the pavement moisture and also changing its resilient properties. The main objective of this research is to study the influence of post-compaction moisture content variation on the resilient modulus of soils from São Paulo state pavements, using laboratory tests. To accomplish this objective, seventy three soils samples were collected and characterized. Among them, thirty samples were selected, after four different tests were carried out to determine the soils genesis, to study the post-compaction moisture content variation. Half of these selected soils are lateritic ones, and the other half are non-lateritic soils. The specimens were compacted at optimum moisture content and submitted to drying and moistening processes prior cyclic triaxial test to be carried out. The results allowed the resilient modulus modeling as a function at the stress state and the performance evaluation of five different models. The genesis and grain size distribution influence on the resilient modulus values were studied. The effects of moisture content variations on lateritic and non-lateritic soils were investigated. An expression to estimate the resilient modulus variations with the moisture variations was determined, independently of the stress state. The existence of relations of the compound model regression parameters with the results of unconfined compressive strength and soil properties were studied. The possibility of using the initial tangent modulus variations with the moisture variations to estimate the effects on the resilient modulus were also investigated.

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