L'objectif est de comprendre d'effet de la turbulence optique sur la mesure au sol du rayon solaire. La mesure du rayon solaire avec précision est importante pour les modèles de structure et d'évolution solaire et stellaire. En plus l'activité solaire a une influence certaine sur le climat terrestre. Le travail de thèse a porté sur la calibration et l'exploitation de données issues des télescopes SODISM2, dédié à la mesure du rayon solaire par imagerie pleine, et MISOLFA un moniteur de turbulence qui permet d'estimer les paramètres spatio-temporels de celle-ci. Les premières mesures de MISOLFA montrent sa capacité pour l'extraction des profils de la turbulence et des paramètres intégrés à partir des fluctuations des angles d'arrivées observées sur le bord solaire. Les paramètres spatiaux issus des fluctuations d'intensité dans la voie pupille montrent un bon accord avec les paramètres issus de la voie image. Les premières mesures du temps caractéristique des angles d'arrivée ont été également obtenues qui donnent une valeur moyenne de 5.3 ms sur une année de mesures. SODISM2 est la copie d'un instrument à bord du satellite PICARD (2010-2014). Les premières mesures de cet instrument montrent une grande stabilité et une dispersion de l'ordre de 200 mas. Une tendance à la baisse de l'ordre de 12 mas/an a été également observée mais elle demeure non significative compte tenu de la dispersion. Une nouvelle méthode a été élaborée pour l'obtention des flat field en utilisant les cartes de contrastes. Des simulations numériques d'imagerie à travers la turbulence montrent un effet systématique des paramètres de la turbulence sur l'estimation du rayon et de la largeur du limbe / The objective is to understand the effect of optical turbulence on ground-based solar radius measurements. The measurement of the solar radius with accuracy is important for models of solar and stellar structure and evolution. In addition solar activity has an evident influence on the terrestrial climate. The work focused on the calibration and exploitation of data obtained by two telescopes: SODISM2 dedicated to the measurement of the solar radius by full-disk imaging, and MISOLFA a turbulence monitor which allows to estimate the turbulence spatio-temporal parameters. The first measurements of MISOLFA show its capacity for the extraction of turbulence profiles and integrated parameters from the angle-of-arrival fluctuations observed on the solar edge. The spatial parameters estimated from the intensity fluctuations in the pupil plane show a good agreement with the parameters coming from the image plane. The first measurements of the angle-of-arrival characteristic time have also been obtained which give an average value of 5.3 ms over a year of measurements. SODISM2 is the qualification model of an instrument on board the PICARD satellite (2010-2014). The first measurements of this instrument show a high stability and a dispersion of the order of 200 mas (milli-arcseconds). A downward trend on the order of 12 mas/year was also observed but it is not significant given the dispersion of the measurements. A new method was developed for obtaining flat fields using contrast maps. Numerical simulations of imaging through turbulence show a systematic bias introduced by the effect of the turbulence parameters on the estimation of the radius and the limb width

The Generic Security Service Application Program Interface (GSS-API) is an architecture that facilitates applications using distributed security services in a mechanism-independent fashion. GSS-API is supported by various underlying mechanisms and technologies such as Kerberos version 5 and public-key technologies. However, no one-time password based GSS-API mechanism existed. This thesis focuses on an investigation using one-time passwords together with RADIUS authentication as a protection facility for a GSS-API mechanism. This thesis presents a security architecture using one-time passwords to establish a GSS-API security context between two communicating peers. The proposed one-time password based GSS-API mechanism could be used to enhance the security of user authentication. Moreover, the mechanism can greatly facilitate static-password based system’s transition to stronger authentication. / IETF GSS-API är ett applikationsgränssnitt (API) som tillhandahåller distribuerade säkerhetstjänster för autentisering och datakonfidentialitet oberoende av den underliggande säkerhetarkitekturen. Applikationer som skrivs mot detta API kan på detta sätt flyttas eller porteras utan att västentligen skrivas om. GSS-API stöds av ett flertal undrliggande säkerhetsarkitekturer som tex Kerberos 5, Windows NTLM och PKI. API har också sk bindings för "C" och Java. I dagsläget finns det dock ingen lösning som baseras på engångslösenord. Denna magisteruppsats har som mål att undersöka möjligheten att använda engångslösenord tillsammans med RADIUS för att implementera en ny GSS-API mechanism. Denna uppsats presenterar ett förslag för hur RADIUS och engångslösenord kan användas för att säkra kommunikationen mellan två GSS-API entiteter. Den föreslagna mekanismen kan också användas för att förbättra säkerheten för användarautentisering och möjliggöra en övergång från statiska lösenord till stark autentisering.

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Distal radius fracture (DRF) is one of the most common fall-related osteoporotic (OP) fracture and is an early predictor of subsequent falls and OP fractures among people with DRF. The majority of older people with DRF present with low bone mineral density (BMD) and there is often transition to reduced muscle strength, poor balance, fear of falling and physically inactive lifestyle after fall-related DRF. This thesis consists of three manuscripts which are aimed to explore the recovery patterns and the role of modifiable risk factors in predicting subsequent falls, OP fractures and BMD in patients with DRF. The first manuscript explores the recovery patterns in modifiable risk factors for falls and OP fractures over four years in patients with DRF. Our study findings showed that patients with DRF experienced both short-term (6 months) and long-term (4 years) improvement in fracture specific pain/disability, physical activity, fear of falling, BMD and general health status; although the majority of the recovery was achieved at six months after DRF. The second manuscript is a cross-sectional study identifying modifiable risk factors for BMD in patients with DRF. The unaffected hand grip strength was identified as the independent predictor of BMD explaining 17% and 12% of total variability in the BMD-femoral neck and BMD-total hip, respectively. Among age-stratified women with DRF, balance and unaffected hand grip strength were identified as independent determinants of BMD explaining 10% and 32% of the total variability in BMD-femoral neck among 50-64 year and 65-80 year old, respectively. The third manuscript is a longitudinal study identifying modifiable risk factors for subsequent falls and OP fractures at four years after DRF. The results suggest that nearly 24% of patients reported one or more subsequent falls (in the last six months) and 19% of patients experienced at least one subsequent OP fracture after DRF. Patients with poor balance, low BMD, fracture specific pain/disability of >81 points on patient-rated wrist evaluation questionnaire and presence of a prior history of multiple falls (≥2) had three times higher odds of subsequent falls. When adjusted for BMD, age and gender, only prior falls was identified as a significant independent predictor of subsequent falls. We were not fully powered to explore association of various modifiable and non-modifiable risk factors with subsequent fractures. However, we found that patients with osteopenia or osteoporosis had clinically four times higher odds of subsequent OP fractures than patients with normal BMD. / Thesis / Doctor of Philosophy (PhD) / Wrist fractures are the most common fall-related fragility fractures and often an early indicator of future falls and fractures. This thesis project described recovery patterns in various risk-factors at 4-years after wrist fracture and explored their association with bone mineral density (BMD) and subsequent falls and fractures. We found that the majority of recovery in fracture-specific pain/disability, fear of falling and health-status takes place within six months, although small changes were also noted between 6 months-4 years. People with low unaffected hand grip-strength might have low BMD. Furthermore, people with poor balance, greater fracture-specific pain/disability, osteopenia or osteoporosis and a prior history of multiple falls (≥2) had nearly 3 times higher odds of secondary falls and those with osteopenia or osteoporosis had 4 times higher odds of a secondary fracture. We believe this information will help therapists/clinicians to identify people at risk of future falls/fractures and offer preventive services.

<p>Some individuals remain at risk for adverse outcomes such as chronic wrist/hand pain, falls, and fall-related osteoporotic fractures after distal radius fracture (DRF) remain. This thesis includes five studies that were conducted to establish prediction rules for assessing the risk of these adverse outcomes following DRF.</p> <p>The first manuscript outlines a theoretical framework (RACE - <strong>R</strong>educing pain, <strong>A</strong>ctivating, <strong>C</strong>ognitive reshaping, <strong>E</strong>mpowering) for managing the risk of adverse outcomes, mainly chronic pain, in individuals with DRF. The RACE is one of the first frameworks to suggest a risk-based management approach for individuals with DRF.</p> <p>The Patient-Rated Wrist Evaluation (PRWE) is a condition-specific measure for DRF used in research as well as clinical practice to measure pain and functions in individuals with different wrist/hand injuries. The second manuscript contributes to the literature by providing the first systematic literature review that synthesizes the evidence regarding the psychometric properties of the PRWE. The review determined that the PRWE has excellent reliability, construct validity, and responsiveness in individuals with DRF.</p> <p>The third manuscript indicates that the baseline pain intensity is an independent predictor of chronic pain in individuals with DRF. The results also suggest that the individuals who score ≥35/50 on the pain scale of the PRWE at baseline have 8 times greater risk for developing chronic wrist/hand pain compared to those who score < 35/50.</p> <p>The fourth and fifth manuscripts describe results of a two step study. The fourth manuscript is a structured literature synthesis that identified suitable measures for predicting the risk of falls and fall-related osteoporotic fractures following DRF. The fifth manuscript summarizes the results of preliminary analysis of psychometric properties of selected fall risk measures identified in the fourth manuscript. The fifth manuscript also provides feasibility and sample size requirements for conducting a fall prevention trial in individuals with DRF.</p> / Doctor of Philosophy (PhD)

Stellar structure is investigated within the framework of scalar-tensor gravity. Novel perturbative analytical results are obtained for constant-density stars and for Newtonian polytropes in the quadratic model with coupling function A(Φ) = exp(αΦ+1/2βΦ^2). They are compared to full numerical calculations, and possible applications to main-sequence stars, white dwarfs, and the Chandrasekhar mass are indicated. It is found that Buchdahl's theorem is violated in Brans-Dicke theory for stars with exponentially-decaying density profiles. However, the mass-to-radius ratio M/R tends to the constant-density value in a certain limit. It is observed that for β < 0, there exists a maximum value of η = P0/ρo for constant-density stars, where P0 and ρ0 are the central pressure and density, respectively. It is conjectured that if such a maximum value also exists for other equations of state, and is less than the constant-density maximum value, then knowledge of P/ρ in the centre of a star can be used to constrain β. / Thesis / Master of Science (MSc)

Central autentisering är en metod som länge har använts för att på ett lätthanterligtsätt administrera användare till olika nätverksresurser såsom datorer, skrivare ochservrar. I en tid när många industrier uppgraderas och byggs ut för att möta nyakrav för att kunna nås från runt om i världen måste många system byggas om.Arbete genomförs tillsammans med HMS Industrial Networks AB och kommer attundersöka möjligheten att autentisera användare mot en inbyggd kontroll ochstyrenhet centralt istället för lokalt vilket det idag är. Teori kommer att blandas medegna experiment av möjliga implementeringar och slutligen utvärderas all fakta ochen slutsats presenteras. / Central authentication is a method that has been around a long time to manage users tovarious network resources, such as computers, printers, and servers. At a time whenmany industries are upgrading and expanding to meet new requirements to be accessedfrom around the world, many systems need to be rebuilt. The work will be donetogether with HMS Industrial Networks AB and will investigate the possibility ofauthenticating users against a built-in controller centrally instead of locally, as it istoday. Theory will be commingled with experiments of possible implementations andfinally evaluated with all the facts and a conclusion will be presented.

La performance des cibles du Laser LMJ est très sensible à l'uniformité de la tache focale du laser. La technique utilisée à ce jour pour éviter les inhomogénéités est de rendre le faisceau partiellement incohérent, ce qui a pour conséquence la fluctuation de points chauds (speckles) au cours du temps, avec un effet de moyenne. De nombreux travaux ont d'ores et déjà été menés concernant l'étude de ces points chauds dans le cadre d'un faisceau unique au plan focal. Dans cette thèse, on s'intéresse à ces points chauds lorsqu'il sont issus de la superposition de faisceaux multiples, et plus particulièrement aux points chauds dans le cas de la configuration du LMJ. On a établi une équation analytique permettant de calculer la taille des points chauds dans le cas d'un speckle généré par des faisceaux multiples. Cette formule est en parfait accord avec les différents résultats obtenus par simulations numériques grâce au code PARAX. On a ainsi pu prédire la taille du grain de speckle LMJ en fonction de différentes configurations LMJ telle qu'une configuration à deux ou trois cônes et pour des choix de polarisations différents. Il en ressort que l'impact de la polarisation est assez faible sur les caractéristiques du speckle LMJ. Toutefois la double polarisation est la plus adaptée aux critères d'uniformité requis pour une bonne interaction laser-plasma. D'autre part on a montré que les grains de speckle LMJ sont de l'ordre de la longueur d'onde.Dans la seconde partie de cette thèse, on a établi les formules des contraste, temps de vie, trajectoires et vitesses des points chauds deux techniques de lissage : Lissage par Dispersion Spectrale Transverse (LDST) et Longitudinal (LDSL). Ces derniers sont respectivement utilisés sur le NIF et prochainement sur le LMJ. On a ainsi montré que quels que soient le nombre de cône et le choix des polarisations faites sur le LMJ, la durée de vie d'un point chaud LMJ est environ de 2 ps et le contraste intégré sur des temps infinis est approximativement de 15%. Les vitesses sont également très faibles (10-6c) et faiblement influencées par le choix des polarisations. / The future French Laser Megajoule (LMJ) is a multiple laser beam facility built to achieve Inertial confinement Fusion (ICF). It is mainly designed for an indirect drive scheme using X-rays conversion. In this scheme, the target in the center of the hohlraum is irradiated and then compressed by the X-rays more uniformly than what it would be in a direct drive schemes. However, a high of uniformity is still needed to reach ignition since the propagation of intense laser beams in an under-critical plasma can generate laser-plasma instabilities (LPI). The control of LPI is of crucial importance for the success of ICF. By breaking both spatial and temporal coherences, the use of optical smoothing techniques, such as smoothing by spectral dispersion (SSD), often dramatically reduces LPI and also ensures the reproducibility of laser conditions from one shot to another. An accurate description of the speckle pattern in the hohlraum is thus of great interest for ICF experiments.We focus our attention on the spatial and then temporal properties of the speckles pattern generated by multiple laser beams. At first, we establish equations for the 3D speckle size based on autocorrelation functions. Numerical simulations of the propagation of multiple laser beams in vacuum are then performed with the PARAX code in configurations where the paraxial approximation can be used. The case of speckle patterns in the LMJ configuration in the zone where all the beams overlap is eventually studied. We show that such speckles have an ellipsoidal shape. Finally, influence of the polarization of the beams on the shape, size and abundance of the speckles is also investigated. In a second part we study the important aspect of temporal smoothing techniques like the movement of the speckles. This work is also triggered by the development of a statistical model that describes the motion of hot spots in order to evaluate the contrast, the trajectory and the velocity of LMJ hot spots. We address these quantities in the case of a speckle pattern generated by multiple laser beams thanks to the autocorrelation function in intensity.

Les fractures de fragilité représentent un problème de santé publique pour les personnes âgées. L'évaluation de la résistance osseuse et du risque de fracture par la méthode de référence (absorption bi-photonique à rayons X, DXA) est limitée. Les micro-modèles en éléments finis (µFEM) ont montré de meilleures prédictions de la résistance osseuse, mais on ne peut confirmer qu’ils améliorent l’estimation du risque de fracture par rapport à la DXA. L'objectif de cette thèse était donc d'évaluer si la prédiction par simulation numérique pouvait être améliorée en prenant en compte des conditions réalistes de chargement. Tout d’abord, les conditions de chargement correspondant à une chute vers l’avant ont été reproduites sur 32 radius humain dans une expérimentation ex-vivo. Les résultats expérimentaux ont conduits à deux groupes : un fracturé et un non fracturé. Puis, la capacité de prédiction d’un modèle « ségment » (9 mm de radius distal) créé en utilisant un scanner à très haute résolution (High Resolution peripheral Quantitative Computed Tomography) a été évaluée. . Différentes configurations (axiale (configuration standard) et 5 non-axiales) ont été simulées. L’implémentation de chargement non-axial n’a pas amélioré la capacité de prédiction du modèle « segment ». Finalement, un modèle hétérogène du radius distal entier a été créé à partir d’un scanner clinique (Cone Beam Computed Tomography). Ce modèle a pris en compte les conditions d’une chute en termes d’orientation et de vitesse. Le modèle de radius distal entier a montré une meilleure prédiction de la charge à la rupture expérimentale que le modèle « segment ». Cette étude propose des données originales pour la validation de modèles numériques pour l’amélioration de la prédiction du risque de fracture / Fragility fractures represent a public health problem for elderly. The assessment of the bone strength and of the risk of fracture by the gold standard method (Dual X-ray Absorptiometry - DXA) is limited. Micro-finite element models (µFEM) have shown to better predict the bone strength, but it is not possible to confirm that they do better than the density measured by DXA to estimate the risk of fracture. Thus, the aim of this thesis was to evaluate whether including realistic loading conditions could improve the level of prediction of the FEM. First, we reproduced the loading conditions of a forward fall on 32 radii in an ex-vivo experiment. This experiment leaded to two groups: one fractured and one non - fractured. Then, we evaluated the prediction capability of a segment FEM (9 mm of the distal radius) created using the High Resolution peripheral Quantitative Computed Tomography. This segment FEM was tested under the axial loading (standard analysis), and under five additional non-axial configurations. It was found that the prediction capability of the segment FEM was not improved by the implementation of non-axial loadings. Finally, a heterogeneous FEM of the whole distal radius was created using data from a Cone Beam Computed Tomography. This model considers the fall loading configurations in orientation and speed of the ex-vivo experiment. The FEM of the whole distal radius has a better accuracy to predict the experimental failure load than the segment FEM. This study proposes original data for model validation dedicated to further improvements of fracture risk prediction

Magnetresonanztomographische Studie zur altersabhängigen Abbildung der Wachstumsknorpel des distalen Radius des Pferdes unter besonderer Berücksichtigung des Epiphysenfugenknorpels. Es wurden magnetresonanztomographische Untersuchungen von 28 Gliedmaßenabschnitten des distalen Radius im Alter von zwei Tagen bis 17 Jahren durchgeführt. Die Studie wurde an einem 1,5 Tesla Magnetom “Symphony“ (Siemens) in vier unterschiedlichen Sequenzen (T1-gewichtet T1w, T2-gewichtet T2w, Protonendichte PD, T2 Double Echo in Steady State T2-dess) und zwei Schnittebenen (dorsal, sagittal) durchgeführt. Die Darstellung der knorpeligen Wachstumsregionen des distalen Radius mit besonderem Hinblick auf seine Epiphysenfuge wurde deskriptiv erfasst und altersbedingte Unterschiede definiert. Die durchschnittliche Dicke des sich darstellenden Epiphysenfugenknorpels wurde in zwei Sequenzen (T1w und T2-dess) vermessen und in Bezug zu dem ansteigenden Alter des Probenmaterials gesetzt. Die Proben konnte man fünf Gruppen zuordnen. In Gruppe 1 konnten sowohl der Wachstumsknorpel der distalen Ossifikationszentren als auch die knorpeligen Anteile der Epi- und Apophysenfugen dargestellt werden. In der Gruppen 2 ließen sich die Apo- und Epiphysenfugen darstellen, in Gruppe 3 nur die Epiphysenfugen. Gruppe 4 beschrieb partiell geschlossene Epiphysenfugen und in Gruppe 5 stellten sich nur 88 noch Fugennarben dar. Eine alterskorrelierende Abnahme der mittleren Knorpeldicke der Epiphyse konnte mittels Vermessungen der Knorpelschichten nachgewiesen werden. Der hyaline Knorpel war mit den gewählten Sequenzen sehr gut beurteilbar. Der Wachstumsknorpel der Epi- und Apophysen stellte sich in den T1w und PD mit hell-intermediärer und in den T2w mit intermediärer Signalintensität dar. Die knorpeligen Anteile der Epi- und Apophysenfuge wurden in T1w intermediär bis hellintermediär, in T2w hell-intermediär und in der PD hell-intermediär bis hyperintens dargestellt. Angrenzende Strukturen wie die subchondrale Knochenplatte und die Mineralisationszone der Epiphysenfuge konnten in dunkel-intermediären bis hypointensen Signalen abgebildet werden. Die Magnetresonanztomographie (MRT) hat sich als geeignetes Verfahren erwiesen, die knorpeligen Strukturen der Wachstumsregion des distalen Radius des Pferdes bildlich wiederzugeben. Altersabhängige strukturelle Unterschiede konnten im MRT dargestellt werden. Damit leistet die vorgestellte Studie einen wichtigen Beitrag über die anatomischen Verhältnisse und deren physiologische Darstellung.