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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.
251

Musculoskeletal pain, memory, and aging : Cross-sectional and longitudinal findings

Söderfjell, Stefan January 2005 (has links)
The general aim of the thesis was to investigate potential differences in memory performance between participants across the adult life span with and without self-reported musculoskeletal pain. Chronic musculoskeletal pain is a major health related problem in our society. A common complaint related to chronic pain is about cognitive difficulties in attention, memory, and decision making. A number of studies have demonstrated that people with pain also perform wors on tasks measuring, for example episodic memory, semantic memory, and working memory. The present thesis aimed at replying these findings, by using a non-clinical population based sample. the potential differences in memory performance between people with and without pain were examined across the adult life span, in order to disentangle potential pain by age interactions. This was made by using both cross-sectional and longitudinal data. Study I aimed at studying differences in episodic memory performance, semantic memory performance, and implicit memory performance, between people with and without musculoskeletal pain. Differences were found for all three memory systems, but disappeared after controlling for years of formal education. In Study II an extension of the first study was made, in which performance on a range of cognitive tests were analysed. General differences were demonstrated , but yet again, years of education together with depression ruled out the effects. The most robust effects were found for word comprehension and construction ability. Finally, Study III used 5- and 10 year follow up studies to examine change over time in cognitive performance as a function of pain. The main finding from this study was that semantic memory for the oldest is impaired over time as a function of pain. An additional analysis showed similar patterns, regardless of age, for construction ability.
252

Nonlinear Analysis Of Reinforced Concrete Frame Structures

Ciftci, Guclu Koray 01 February 2013 (has links) (PDF)
Reinforced concrete frames display nonlinear behavior both due to its composite nature and the material properties of concrete itself. The yielding of the reinforcement, the non-uniform distribution of aggregates and the development of cracks under loading are the main reasons of nonlinearity. The stiffness of a frame element depends on the combination of the modulus of elasticity and the geometric properties of its section - area and the moment of inertia. In practice, the elastic modulus is assumed to be constant throughout the element and the sectional properties are assumed to remain constant under loading. In this study, it is assumed that the material elasticity depends on the reinforcement ratio and its distribution over the section. Also, the cracks developing in the frame element reduces the sectional properties. In case of linear analysis, the material and sectional parameters are assumed to be constant. In practice, the modulus of elasticity E is a predefined value based on previous experiments and the moment of inertia I is assumed to be constant throughout the analysis. However, in this study, E and I are assumed to be combined. In other words, they cannot be separated from each other throughout the analysis. These two parameters are handled as a single parameter as EI . This parameter is controlled by the reinforcement ratio and its configuration, sectional properties and deformation of the member. Two types of analysis, namely a sectional and a finite element analyses, are used in this study. From the sectional analysis, the parameter EI is calculated based on the sectional geometry, material properties and the axial load applied on the section. The parameter EI is then used in the finite element analysis to calculate the sectional forces and the nodal displacements. For the nonlinear analysis, the Newton-Raphson iterative approach is followed until convergence is obtained.
253

Estudio ecográfico (ecogenicidad y área) de los tendones flexores de la extremidad anterior del caballo Pura Raza Español

Martínez Martínez, Mª de los Llanos 25 April 2005 (has links)
La ecografía es una técnica ampliamente utilizada para evaluar las lesiones tendinosas en los caballos, hasta este momento no se ha realizado ningún estudio sobre la ecogenicidad y el área de los tendones flexores y ligamentos de la zona metacarpiana del Pura Raza Español (P.R.E). El objetivo de nuestro estudio es determinar el área y la ecogenicidad de los tendones flexores y ligamentos de la zona del metacarpo, y determinar si tiene algún efecto la edad, el sexo, la extremidad y la zona de corte a ecografiar sobre estos parámetros en el caballo PRE.De este trabajo podemos concluir que la edad y la zona del metacarpo donde se realiza el examen tienen un efecto tanto en la ecogenicidad como en el área. Mientras que la extremidad sólo influye en los valores del área. Sin embargo, no se encontró ninguna diferencia entre machos y hembras ni en la ecogenicidad ni en los valores del área. / The ultrasonographic assessment of tendon injuries can be based on several criteria. The purposes of this study were to establish normal values for CSA and ME of flexor tendons and ligaments of the metacarpal region of Andalusian horses; to determine the normal relation between the different tendons and ligaments; to determine the normal relation between the male and female for each tendon and ligament; to determine the normal relation between the left and right limbs for each tendon and ligament and to determine the normal relation between different age (young, adult and senile) for each tendon and ligament.In conclusion, this work suggests that the age and level have an effect on CSA and ME of the tendons and ligaments. The limb has also an effect on CSA of each tendon and ligament. Differences in CSA or ME of each tendon were not found between males and females.
254

A non-linear coupled model for the analysis of reinforced concrete sections under bending, shear, torsion and axial forces

Bairán García, Jesús Miguel 15 December 2005 (has links)
La mayoría de las estructuras de hormigón armado se someten a solicitaciones combinadas de esfuerzos axiles, flexión, cortante y torsión. La fisuración del hormigón, plastificación de las armaduras y otros efectos no-lineales hacen que las secciones transversales de estos elementos presenten un comportamiento anisótropo que deriva en el acoplamiento de los esfuerzos normales y tangenciales. Es decir, esfuerzos normales o momentos flectores pueden producir deformaciones de corte y vice versa. Aunque en algunas ocaciones, esta interacción es considerada de forma simplificada en el dimensionamiento de estructuras, hasta el momento no se ha realizado un análisis profundo de los efectos acoplados en secciones de forma arbitraria bajo cargas 3D generales utilizando modelos de fibras.El objetivo principal de esta tesis es generalizar el análisis de secciones de hormigón armado mediante fibras, de forma que se pueda reproducir la res-puesta no-lineal acoplada frente a esfuerzos normales y tangenciales bajo solicitaciones tridimensionales generales. De igual forma, se pretende obtener, para los esfuerzos cortantes y torsión, la misma capacidad de representación de geometrías y combinación de materiales que ofrecen los modelos de fibras para esfuerzos de flexo-compresión.La primera problemática estriba en representar adecuadamente la cinemática de la sección transversal. Con la excepción de las deformaciones normales contenidas en el plano de la sección, no existe una teoría cinemática que a priori pueda dar la distribución del resto de deformaciones o tensiones en la sección, sin dejar de satisfacer las condiciones de equilibrio interno o continuidad entre las fibras que componen la misma.Por otra parte, para materiales anisótropos, como el hormigón fisurado, en general todos los esfuerzos internos pueden estar acoplados. Además, es preciso considerar la distorsión de la sección transversal para satisfacer el equilibrio entre fibras.El problema se aborda de forma general, considerando una sección de forma y materiales cualesquiera. Se parte del problema diferencial de equilibrio de un sólido con el que se ha podido deducir un sistema de equilibrio entre fibras (equilibrio a nivel sección). Se puede demostrar que éste es complementario al problema estándar de vigas. El sistema complementario permite recuperar información tridimensional que normalmente se pierde al resolver un problema de vigas.Posteriormente, se propone una solución interna del problema complementario, en la que el alabeo y la distorsión de la sección quedan expresados como una función de las deformaciones generalizadas de una viga: deformaciones axil y cortantes, curvaturas de flexión y torsión. No son necesarios grados de libertad adicionales a nivel estructura ni hipótesis a-priori sobre la forma de los campos de deformación o tensión interna.A partir de la formulación teórica, se desarrolla un modelo de elementos finitos plano de la sección transversal. El modelo está preparado para servir como respuesta constitutiva de cualquier tipo de elemento viga en sus puntos de integración. %Se evita así la necesidad de realizar un modelo de elementos sólidos de toda la barra para estudiar la respuesta frente a una combinación general de esfuerzos normales y tangenciales.Se implementan una serie de modelos constitutivos para distintos materiales. En particular, se implementa un modelo constitutivo triaxial para hormigón fisurado, considerando la anisotropía inducida por la fisuración e incluyendo la superficie de rotura según un criterio multiaxial.La formulación seccional es validada mediante varios casos de estudio teóricos y experimentales. La respuesta no-lineal acoplada bajo diversas combinaciones de esfuerzos normales y tangenciales es reproducida con precisión, lo cual queda patente tanto en las curvas esfuerzo-deformación obtenidas como en las matrices de rigidez seccionales.Finalmente, se recopilan las conclusiones derivadas de la presente investigación y seofren recomendaciones para futuros trabajos. / Most RC structures are subjected to combined normal and tangential forces, such as bending, axial load, shear and torsion. Concrete cracking, steel yielding and other material nonlinearities produce an anisotropic sectional response that results in a coupling between the effects of normal and shear forces, i.e. normal force or bending moments may produce shear strains and vice versa. Although this interaction is sometimes taken into account, in a simplified manner, in the design of RC structures, a deep analysis of the coupling effects of RC sections using fiber models has not yet been made for arbitrary shape sections under general 3D loading.The main objective of this thesis is to generalize the fiber-like sectional analysis of reinforced concrete elements, to make it capable of considering the coupled non-linear response under tangential and normal internal forces, from a general 3D loading.Similarly, it is desired to obtain, for torque and shear forces, the same capacity and versatility in reproducing complex geometry and materials combination that fiber-like sectional representations offers for bending and stretching.The first problematic lies in finding a proper representation of the section's kinematics under such general loading. Except for in-plane normal strains, there is no single kinematical theory capable of a-priori representing the correct distribution of the others strains or stresses satisfying, at the same time, inter-fiber equilibrium and continuity. On the other hand, for rather anisotropic materials, such as cracked concrete, all internal forces are, in general, coupled. It is also required that distortion is allowed for the section's kinematics in order to guarantee satisfaction of internal equilibrium.The problem is dealt in a general form considering arbitrary shaped sections and any material behaviour. Starting from the differential equilibrium of a solid, an inter-fiber equilibrium system (equilibrium at the sectional level) was deduced. This system, which is complementary to the standard equilibrium problem of a beam-column, allows to recuperate information of the three-dimensional problem that is generally lost when solving a beam problem.Further, a solution of the equilibrium at the sectional level is proposed in which the section's warping and distortion are posed as a function of the generalized beam-column strains (axial and shear strains, bending and torsion curvatures). No additional degrees of freedom are required at the structural level nor a-priori hypotheses on the distribution of the internal strains or stresses.After the theoretical formulation, a planar finite element model for cross-sectional analysis is developed. The model can be used as a constitutive law for general beam column elements at their integration points.A series of constitutive models have been implemented for several materials. In particular, a triaxial constitutive model for cracked concrete is implemented considering crackinduced anisotropy and a multiaxial failure criterion.The sectional formulation is validated by means of various theoretical and experimental case studies. Non-linear coupled response under normal and tangential internal forces is reproduced with accuracy, as can be seen both in the predicted internal force-strain curves and in the sectional stiffness matrixes.Finally, the conclusions drawn from the current research are summarized andrecomendations for future works are given.
255

Use Of Helical Wire Core Truss Members In Space Structures

Isildak, Murat 01 May 2009 (has links) (PDF)
In an effort to achieve lighter and more economical space structures, a new patented steel composite member has been suggested and used in the construction of some steel roof structures. This special element has a sandwich construction composed of some strips of steel plates placed longitudinally along a helical wire core. The function of the helical core is to transfer the shear between the flange plates and increase the sectional inertia of the resulting composite member by keeping the flange plates at a desired distance from each other. Because of the lack of research, design engineers usually treat such elements as a solid member as if it has a full shear transfer between the flanges. However, a detailed analysis shows that this is not a valid assumption and leads to very unsafe results. In this context, the purpose of this study is to investigate the behavior of such members under axial compression and determine their effective sectional flexural rigidity by taking into account the shear deformations. This study applies an analytical investigation to a specific form of such elements with four flange plates placed symmetrically around a helical wire core. Five independent parameters of such a member are selected for this purpose. These are the spiral core and core wire diameters, the pitch of the spiral core, and the flange plate dimensions. Elements with varying combinations of the selected parameters are first analyzed in detail by finite element method, and some design charts are generated for the determination of the effective sectional properties to be used in the structural analysis and the buckling loads. For this purpose, an alternative closed-form approximate analytical solution is also suggested.
256

The Role Of Sais In Promoting Sustainable Development: Environmental Auditing

Erkan, Berna 01 January 2012 (has links) (PDF)
This thesis is based on cross-sectional data analyses by using Ordinary Least Squares (OLS) Method in order to determine the main drivers of the environmental performance and specifically the effects of environmental audits conducted by Supreme Audit Institutions (SAIs) on sustainable development. Two general models are employed throughout the study that have the Environmental Performance Index (EPI) as dependent variable and various sub-models for different income groups are produced to observe the individual and interactive effects of explanatory variables. First model includes 150 countries regressing their EPI scores on income, population, literacy rate and indicators of the strength of institutional structure such as corruption perceptions index or government effectiveness score. Then, second model which comprises 52 countries introduces the number of environmental audit reports as a new explanatory variable. Principal Component Analysis (PCA) is also applied to highly correlated variables and the models are reestimated. The results indicate that well functioning environmental management systems and resulting positive effects on the environmental performance can only be attained through strengthened governmental institutions with high transparency and accountability as well as rigid implementation of the related regulations. More specifically, environmental audit reports generated by SAIs are of vital importance for especially improving the environmental management systems of the developing countries.
257

Detection of Parkinson's disease from MR images / Ανίχνευση της ασθένειας Πάρκινσον απο μαγνητικές τομογραφίες

Thanellas, Antonios-Constantine 22 July 2008 (has links)
The scope of this thesis is to process and analyze statistically Magnetic Resonance Images (MR-T1) from Parkinson’s disease patients in order to detect brain areas that exhibit brain change which is caused by the disease. Parkinson’s disease is an idiopathic disease which means that its cause is yet unknown. It is a chronic neurodegenerative disorder of the central nervous system which causes the progressive death of specific brain neurons that leads to motor impairments (tremor, bradykinesia, muscle rigidity) and non motor ones (cognitive, sleep, sensation disturbances). Magnetic Resonance Images (T1-weighted) were acquired from both Parkinson’s patients and healthy subjects (Controls) at intervals of 0 and 5 years. The data have undergone longitudinal (two-time-point), cross sectional (single-time-point) and statistical analysis with the use of FSL software library. Evidence of atrophy among Parkinson’s patients aroused, in brain areas near the ventricles and the middle temporal gyrus, after statistical analysis / Ο σκοπός αυτής της εργασίας είναι η επεξεργασία και στατιστική ανάλυση μαγνητηκών τομογραφιών (MR-T1) από ασθενείς με Πάρκινσον για την ανίχνευση περιοχών του εγκεφάλου που παρουσιάζουν μεταβολές που οφείλονται στην ασθένεια. Η ασθένεια Πάρκινσον είναι ιδιοπαθής, δηλαδή ασθένεια της οποίας η αιτία παραμένει ακόμη άγνωστη. Είναι μια χρόνια δυσλειτουργία λόγω εκφυλισμού των νευρώνων του κεντρικού νευρικού συστήματος η οποία προκαλεί τη σταδιακή νεκρωση συγκεκριμένης ομάδας εγκεφαλικών νευρώνων. Αυτή η νέκρωση οδηγεί σε κινητικές δυσλειτουργίες (τρέμουλο, βραδυκινησία, και μυϊκή δυσκαμψία και σε μή κινητικές όπως γνωστικές, διαταραχής ύπνου,διαταραχές αφής κ.α. Μαγνητικές τομογραφίες (τύπου Τ1) ασθενών και υγιών ελήφθησαν σε διαστήματα 0 και 5 ετών. Τα δεδομένα αναλύθηκαν με δυο μεθόδους (longitudinal και cross-sectional) και εν συνεχεία έγινε στατιστική επεξεργασία των αποτελεσμάτων. Έγινε χρήση της βιβλιοθήκης FSL Μετά από στατιστική ανάλυση προέκυψαν ενδείξεις ατροφίας στους ασθενείς με Πάρκινσον σε περιοχές του εγεκφάλου κοντά στις εγκεφαλικές κοιλίες (ventricles) και στη μέσο-κροταφική έλικα (middle temporal gyrus).
258

Dementia, depression and delirium in the very old : prevalences and associated factors

Mathillas, Johan January 2013 (has links)
Emotional suffering in old age is largely caused by a variety of psychiatric disorders which are often, however, undertreated and underrecognized. This leads to reduced quality of life and functional status and increased morbidity and mortality. Dementia, delirium and depression are common disorders in the very old, and are similar in several ways. All have multiple causes and are diagnosed by means of symptomatic criteria, are challenging to diagnose and difficult to differentiate from each other in the very old. They often coexist in the same individual, and may have common risk factors. The overall aim of this thesis was to add to our knowledge about threats to successful aging, by investigating the prevalences of dementia, depression and delirium, and factors associated with these three disorders. Further aims were to measure change over time in the prevalence of dementia and depression, respectively, and to investigate the risk factors for incident depression. This thesis uses the population-based Umeå85+/GErontological Regional DAtabase (GERDA) material. In 2000-2002, every other 85-year-old, all 90-year-olds and all people ≥95 years living in six municipalities in Västerbotten, Sweden were invited to participate, and in 2005-2007 the process was repeated, with the additional inclusion of the corresponding populations of two municipalities in Österbotten, Finland. A third data collection was carried out in 2010-2012. Trained assessors carried out assessments in the form of structured interviews during one or more home visits, recorded current medication and reviewed medical records obtained from general practitioners and hospitals. In 2000-2002 the prevalence of dementia was 17% among 85-year-olds, 24% among 90-year-olds and 46% among those aged ≥95 years. In 2005-2007 dementia prevalence reached 28% among 85-year-olds, 40% among 90-yearolds and 45% among those aged ≥95 years. The prevalence of dementia in the total sample was 27% in 2000-2002 and 37% in 2005-2007 (p=0.001). In 2000-2002 the prevalence of depressive disorders was 24% among 85-yearolds, 34% among 90-year-olds and 31% among those aged ≥95 years. In 2005-2007 the prevalence of depressive disorders was 33% among 85-year-olds, 39% among 90-year-olds and 38% among those aged ≥95 years. The prevalence of depressive disorders in the total sample was 29% in 2000-2002 and 37% in 2005-2007 (p=0.025). Among participants not depressed at baseline, 26% had developed depression after five years. Factors independently associated with new cases of depression at follow-up were hypertension, a history of stroke and a higher score on the 15-item Geriatric Depression Scale at baseline. The thirtyday prevalence of delirium in 2005-2007 was 17% among 85-year-olds, 21% among 90-year-olds and 39% among participants aged ≥95 years. Delirium prevalence among individuals with dementia was higher than among those without dementia (52% vs. 5%, p<.001). Factors independently associated with delirium superimposed on dementia in a multivariate logistic regression model were depression, heart failure, living in an institution and prescribed antipsychotics. There was a high prevalence of dementia, depression and delirium in the papers comprising this thesis, and 55% had at least one of the three disorders. The prevalence of dementia and depression also increased between 2000-2002 and 2005-2007, after controlling for age and sex. Dementia and depression were important associated factors for delirium and half of those with dementia were depressed. The increasing age-specific prevalence of depression seems to be associated with the increasing age-specific prevalence of dementia. The papers presented are among the first to report a significantly increasing age-specific prevalence of dementia and depression among very old people. More knowledge about associated factors and risk factors concerning these disorders may be helpful for carers and decision-makers, as well as providing reference values for studies in other regions. Further efforts are needed in both care and research to better prevent, screen for, diagnose and treat dementia, depression and delirium, especially considering the growing number of very old people. / Umeå85+/GERDA
259

Knowledge, Attitude and Sexual Behaviors with Regard to HIV/AIDS among Upper Primary School Pupils in Meru District, Arusha, Tanzania

Kasilima, Yosh Sospater January 2010 (has links)
<p>A cross- sectional descriptive study using a self-administered close-ended questionnaire was conducted with pupils in standards four to seven (aged 10 &ndash / 17 years) in ten government primary schools in Meru District. The sample of 400 school pupils was obtained by a simple random sampling technique. Data analysis was done using Statistical Package for Social Sciences SPSS (version 15) computer software and the results were presented in frequencies using simple percentages, tables and graphs. The Chi-square test was used to assess the significance where a p-value of &lt / 0.05 was considered statistically significant. In conclusion, Primary school pupils in Meru district engage in several risky sexual behaviors including substance use, sexual coercion, early sexual debut and engaging in various sexual practices. This calls for a more comprehensive approach in the fight against HIV among primary school children in Tanzania, which could include life skill training at an early age, behaviour change communication interventions, advocacy activities to influence policy formulation, condom promotion and incorporating key stakeholders in the rollout of school based HIV programmes such as parents, community leaders and faith-based organizations leaders.</p>
260

Mr.

2015 February 1900 (has links)
Rotator cuff pathologies involving supraspinatus are a common cause of musculoskeletal morbidity and can lead to significant disability affecting the overall quality of life. Architectural parameters of the muscle directly influence its functional properties. Therefore, understanding of fiber bundle changes with surgery and different exercises can assist clinicians in planning better surgical and shoulder rehabilitative protocols. The first objective of this thesis was to systematically review human cadaveric studies of the normal supraspinatus architecture and highlight the key aspects that should be considered while performing studies of skeletal muscle architecture. The second objective was to understand the impact of surgical repair on the structural and functional recovery of the supraspinatus. The final objective was to provide a scientific rationale behind choosing an exercise to strengthen supraspinatus by investigating its muscle architecture. Study 1 systematically reviewed human cadaveric studies of the normal supraspinatus architecture. Results showed that the overall quality of majority of included is poor and there was a large range in the reported architectural values of the entire muscle. In conclusion, there were only a few studies providing the level of detail and quality suitable for advancing our understanding of shoulder biomechanics. Study 2 quantified and compared the fiber bundle architecture of the pathologic supraspinatus pre- and post-operatively at multiple time points. Results showed significant lengthening of fiber bundles after one month of surgery which then decreased significantly by 6 months of surgery. In contrast, an initial decrease followed by an increase in pennation angle overtime was found. The results suggest that the stretching applied to the tendon and muscle during repair could affect the length-tension relationship of the muscle, which in turn can compromise its function and may lead to inferior surgical outcomes. Study 3 compared the efficacy of three commonly prescribed supraspinatus strengthening exercises in the rehabilitation setting based on the architectural changes following resistance training. Results showed there was no change in FBL and increased strength after resistance training with prone horizontal abduction exercise. Findings suggest that prone horizontal abduction may be a more suitable exercise to strengthen supraspinatus.

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