Ce travail de thèse étudie la dynamique et la cohérence du spin dans des ensembles de boîtes quantiques (BQ) neutres et dopées en trous d'InAs/GaAs. Les études sont menées grâce à des expériences pompe-sonde résonnantes avec la transition fondamentale. Dans un premier temps, la périodicité de l'excitation laser est transférée à la précession des spins de trous en champ magnétique transverse, dans le cadre du blocage de phase (Modelocking). Cette technique permet de passer outre les fortes inhomogénéités de l'échantillon étudié ( 105 BQ), et d'observer une resynchronisation des spins à des délais longs. On peut ainsi estimer le temps de cohérence de spin du trou, à 800 ns. De plus, des conditions expérimentales proches nous ont permis d'observer une polarisation nucléaire dynamique (PND), et ses effets importants sur la précession électronique en champ transverse. La géométrie de la PND a été caractérisée, et on a également mesuré la dynamique longue de son établissement (500 ms). Dans une deuxième partie, le développement d'une détection hétérodyne a permis d'augmenter fortement la sensibilité du dispositif pompe-sonde, et ainsi d'étudier des ensembles restreints (300) de BQ neutres dans une cavité. Nous avons caractérisé la structure fine des états de paire électron-trou en présence d'un champ magnétique longitudinal et mis en évidence la manipulation de la phase des battements quantiques de ces états par le champ magnétique lors d'une excitation linéairement polarisée selon un axe sui n'est pas axe de symétrie des BQ. / This work is a study of the dynamics and coherence of the spin in neutral and p-doped InAs/GaAs quantum dots (QDs) ensembles. The study is done thanks to pump-probe experiments, resonant with the fundamental transition. Firstly, the periodicity of the exciting laser is transferred to the precession of the hole spins in a transverse magnetic field, in the Modelocking frame. This techniques allows to overcome the strong inhomogeneities of the sample studied ( 105 QDs), and to observe a resynchronization of the spins at long delays. We can therefore estimate the coherence time of the hole spin to be 800 ns. Furthermore, similar experimental conditions allow us to observe dynamical nuclear polarization (DNP), and its important influence on the electron spin precession in a transverse field. The geometry of the DNP is characterized, and its long dynamic (500 ms) is measured. In a second part, the development of a heterodyne detection allows to improve greatly the sensitivity of the pump-probe setup, and hence to study small ensembles (300) of neutral QDs embedded in a cavity. We have characterized the fine structure of the electron-hole pair states in a longitudinal magnetic field, and demonstrated the manipulation of the phase of the quantum beats between these states by the magnetic field, when the excitation is done according to an axis that is not a symmetry axis of the system.

Le laser est omniprésent dans la recherche et les applications. Les efforts de miniaturisation, qui affectent le développement de sa cohérence, se sont multipliés depuis sa découverte, mais seulement avec les plus petits Lasers à Emission Verticale (VCSELs) on détecte l'influence du volume de cavité sur les propriétés d'émission. Ainsi on se pose des questions sur l'apparition et le développement de la cohérence, sur la valeur (unique ?) du seuil laser, sur l'existence d'un tel seuil dans un nanolaser et sur la réponse à la modulation du pompage. Dans cette thèse, nous explorons le fonctionnement du laser autour du « seuil » pour obtenir des réponses expérimentales à quelques-unes des questions posées dans des lasers à la meso-échelle. Les fonctions de corrélation, la dynamique temporelle, la reconstruction de l'espace des phases, des indicateurs statistiques et des mesures spatialement résolues d'intensité et de longueur d'onde d'émission sont les indicateurs utilisés dans cette étude. La dynamique est étudiée modulant sinusoïdalement des petits VCSEL, où nous obtenons : des impulsions dans la région du seuil, amplification anormale de l'émission spontanée (en polarisation croisée), oscillations régulières et (surtout) irrégulières par la forte influence de l'émission spontanée dans ces petits dispositifs. Enfin, une caractérisation bidimensionnelle des propriétés du rayonnement, transversalement à l'émission, montre la corrélation entre la croissance de la cohérence et celle du mode laser. Pour les dispositifs plus grands, cette analyse jette les bases pour l'étude du développement de la cohérence dans les lasers spatialement étendus. / Coherent light sources are nowadays ubiquitous in scientific research and engineering applications and have been miniaturized since their inception. Physically, the onset and development of laser coherence is largely affected by the cavity size reduction, but this becomes apparent only for the smallest Vertical Cavity Surface Emitting Lasers (VCSELs). Thus the following questions arise: When does coherence set in? How does it develop? How do we define threshold? Is there a unique threshold value and does it exist at all for a nanolaser? What is the dynamical response to modulation in this uncharted territory? In this thesis we explore the regime of laser operation around what is conventionally called the threshold point and obtain experimental answers to some of the questions from mesoscale lasers. Correlation functions, temporal dynamics, phase space reconstruction, statistical indicators and spatially-resolved intensity and emission wavelength measurements are the indicators for the answers we seek. The dynamical response is investigated by applying a sinusoidal modulation to very small VCSELs, where we obtain the amplification of pulses in the threshold region, anomalous amplification of the spontaneous emission (in a cross-polarized channel), regular and (mostly) irregular pulsations due to the strong influence of spontaneous emission in these small devices. Finally, a two-dimensional characterization of the radiation properties transversely to the emission shows the correlation between coherence buildup and the establishment of a laser mode. For larger devices, this analysis lays the foundation for investigating the buildup of coherence in spatially extended lasers.

Dental erosion has been defined as a chemical process that involves the dissolution of enamel and dentine by acid(s) not derived from bacteria when the surrounding aqueous phase is under-saturated with tooth mineral. Clinically however, dental erosion hardly ever occurs exclusively from the other modes of tooth wear such as abrasion and attrition. Hence the term erosive wear has been proposed and used to describe erosion-facilitated wear.With the prevalence of erosive wear being reported to be on the rise among children and adolescents in many countries, a plethora of oral health products such as dentifrices and mouth rinses had been put forward with claims of increasing the resistance of the enamel and / or dentine from being demineralised. However, the efficacy of these oral health products is still widely questionable as the studies carried out were mainly in vitro and / or in situ studies and the contradictory results were reported by different groups of researchers.The above mentioned discrepancies are often due to non-standardised in vitro and in situ study designs of erosion studies. Parameters such as type of acid used, concentration of acid used, duration of acid exposure, inclusion or exclusion of abrasion in the study model, ex vivo or in vivo acid challenge, ex vivo or in vivo treatment with oral health product and the nature of pellicle on the specimen are often varied.The availability of an detection tool which could be used to measure demineralisation on natural tooth surface in vivo would exclude many of the inevitable variability in in situ and in vitro study design, such as the simulation of the intra oral conditions in which the erosion challenge and intervention take place and the nature of the pellicle formed on the specimens. Hence with an in vivo detection tool, it is hopeful that the efficacy of any interventions would be evaluated more accurately and its results expounded to a wider context. It would be useful if the tool was sensitive to the very early stages of the erosion process as this would entail shorter and more economical study designs. Arising from the problems discussed above, potential non-invasive assessment methods that could be used clinically to measure demineralisation were explored and it was found that two optical methods, Optical Coherence Tomography (OCT) and Quantitative Light-induced Fluorescence (QLF) were potential methods for the tasks.The studies described in this thesis were divided into three main big sections; the first being the in vitro validation work of the two optical methods (Chapter 5 and 6), the second, validation of these methods in situ (Chapter 7) and finally the assessment of the efficacy of a high fluoride dentifrice on early enamel erosion using these two methods (Chapter 8).In the in vitro validation (Chapter 5), it was demonstrated that both QLF and OCT were able to detect erosion-interval related changes in natural surface samples eroded with orange juice for 60 minutes. However, results of Multiple Linear Regression and Paired t test suggest that QLF was more sensitive than OCT in the detection of demineralisation changes in this particular experimental setting. QLF demonstrated a R2 value of 0.590 while the best of the OCT outcome measure demonstrated a R2 value of 0.319.Further in vitro study (Chapter 6) was performed to explore the use of a moistened-exposed surface as a reference method for both OCT and QLF as it was felt that it would be beneficial if a coated reference area which posts as an additional step for error could be done away with. Results of this study showed that the moistened-exposed surface could be used a reference method for QLF only but not for OCT. Furnished with the findings of the above mentioned in vitro validation studies, an in situ validation of both the optical methods was performed (Chapter 7). It was found that OCT and QLF were able to longitudinally measure in situ demineralisation on polished and natural surfaced enamel which were subjected to 150 minutes of in vivo exposure to orange juice. Similar to the results of the in vitro study, QLF was found to be more sensitive than OCT in the detection of demineralisation changes on natural surfaced enamel. The last in situ study (Chapter 8) was to evaluate whether there was a protective effect of treating human enamel with a high-concentrated fluoride dentifrice during an active erosion phase and whether OCT and QLF were able to detect the protective effect. It was found that treating natural surface enamel with a 5000ppm NaF dentifrice increased its resistance against concurrent in vivo erosive challenge with an orange juice challenge. QLF was able to detect the protective effect of the 5000ppm NaF dentifrice on natural surface enamel against early in vivo erosion with an orange juice challenge regime while OCT did not.

Aim: The overall aim of this thesis, using a salutogenic framework, was to develop knowledge about experiences and perceptions of living with recessive limb-girdle muscular dystrophy and its influences on health, from the affected young adults’ and their parents’ perspectives. Methods: A qualitative explorative and descriptive study design was used. Semi-structured interviews were held with 14 young adults diagnosed with recessive limb-girdle muscular dystrophy, aged 20–0 years, and 19 parents. Data analyses were conducted using content analysis (I, II, III) and phenomenography (IV). In order to mirror the interview data, the participants also answered the 13-item sense of coherence questionnaire. Findings: Recessive limb-girdle muscular dystrophy has a major impact on the affected young adults’ and their parents’ lives as the disease progresses. Health described in terms of well-being was thus perceived to be influenced, not only by physical, emotional and social consequences due to the disease and worry about disease progression but also by external factors, such as accessibility to support provided by society and other people’s attitudes. There was, however, a determination among the participants to try to make the best of the situation. The importance of being able to mobilize internal resources, having social support, meaningful daily activities, adapted environment, the young adult being seen as a person and having support from concerned professionals, including personal assistance when needed, was thereby described. Self-rated sense of coherence scores varied. Those who scored above or the same as median among the young adults (≥56) and the parents (≥68) expressed greater extent satisfaction regarding social relations, daily activities and external support than those who scored less than median. Conclusion: This thesis highlights the importance of early identification of personal perceptions and needs to enable timely health-promoting interventions. Through dialogue, not only support needed for the person to comprehend, manage and find meaning in everyday life can be identified, but also internal and external resources available to enhance health and well-being, taking into account the person’s social context as well as medical aspects.

Aim: To investigate families’ perceived life situation when living with cancer, with a focus on health and family sense of coherence. Methods: Study I is a population-based register study that explored how cancer influenced the health of cohabitating partners of persons with cancer in Sweden by examining the onset of new diagnoses, health care use, and health care costs among the partners. Study II focused on familial interaction patterns for families living with cancer in a palliative phase, based on family interviews, and analysed using Gadamerian hermeneutics. In study III, Family Sense of Coherence scale (S-FSOC-S) was culturally adapted and evaluated for reliability and validity, using psychometric analyses. Study IV explored associations between family sense of coherence and hope, anxiety, and symptoms of depression using descriptive statistics and nested linear regression. Results: Study I showed that the partners of persons with cancer had significantly increased health care use and health care costs both one and two years after the cancer diagnosis, and that use patterns and costs varied according to the type of cancer that had been diagnosed. Study II revealed that the familial interaction patterns were adjusted in response to changes in family life - changes which encompassed three different, but interrelated, patterns: power dynamics in the family, the “secret game” in the family, and multifaceted closeness and distance in the family. Study III suggested that S-FSOC-S is useful for assessing familial coherence and shows satisfactory reliability and validity. Study IV showed that stronger family sense of coherence was associated with higher hope and lower anxiety and symptoms of depression levels in both persons with cancer and their family members. Conclusions: Families’ life situation was affected by the cancer diagnosis, which had an impact on both individual family members and the family as a unit. The type of cancer may help to determine partners’ risk of ill health. The changed familial interaction patterns increased the families’ ability to deal with family life without hurting each other. The S-FSOC-S is a useful instrument for assessing family sense of coherence and can help identify families with weak family sense of coherence, who may need professional support.

Gekrümmte Röntgen-Multilagen-Spiegel fokussieren Synchrotron-Strahlung auf wenige zehn Nanometer große Strahlflecke. Die Propagation zweier Lichtwellen durch elliptisch geformte fokussierende Multilagen-Spiegel wird durch eine wellenoptische Theorie beschrieben; dieser analytische Ansatz wird numerisch integriert. Mit diesem Verfahren kann die Schichtstruktur für hohe Reflektivität und geringe Strahl-Aberrationen optimiert werden. Wir zeigen Simulationen aktueller und neu entwickelter Synchrotron-Strahlrohre. Die Grenzen der Theorie werden anhand von Modell-Parametern untersucht.Ein weiterer Teil dieser Arbeit beschäftigt sich mit partieller räumlicher Kohärenz, modelliert mit der Methode der stochastischen Superpositionen. Propagation und Filterung der Kohärenzeigenschaften eines Röntgenstrahls in einem Wellenleiter werden analytisch und numerisch untersucht. Das vorgestellte, anschauliche Modell soll die Entwicklung und Überprüfung neuer Algorithmen im Bereich der kohärenten Abbildung unterstützen. Wir vergleichen die Ergebnisse von Simulationen, die auch Realstruktureffekte berücksichtigen, mit experimentellen daten aus dem GINIX-Instrument am Kohärenz-Strahlrohr P10 an der PETRA III-Quelle am DESY.Diese Arbeit zeigt Ergebnisse aus einer Kollaboration zwischen der Georg-August-Universität Göttingen und der European Synchrotron Radiation Facility (ESRF) in Grenoble.

Background: Expecting a child and becoming a parent is one of life’s major events, during which the parents’ perspective on life and their couple relationship changes. For some parents, childbearing entails a decrease in parental couple relationship quality. The way in which parents are able to cope with childbearing may be connected with their Sense of Coherence; which is a person’s ability to perceive life as comprehensible, manageable and meaningful. For parents’ positive childbearing experiences, professional and social support have been proven to be valuable. However, far from all parents have access to social support; furthermore, professional support does not always meet the needs of expectant parents. Hence, more research is needed to increase knowledge about expectant parents’ experiences of professiona land social support. In addition, more research is needed to explore factors associated with quality of couple relationship among parents during childbearing. Aims: The overall aim of the thesis was to explore professional and social support for first-time mothers and partners during childbearing in relation toquality of couple relationship and Sense of Coherence. Methods: The study’s designs were explorative, prospective and longitudinal; both qualitative and quantitative methods were used. Specifically, explorative designs, qualitative methods and phenomenographic analysis were used to explore expectant first-time mothers’ (I) and partners’ perceptions of professional support (II). Furthermore, an explorative design, qualitative method and qualitative content analysis were used to explore expectant first-time mothers’ experiences of social support (III). Within Study IV, a prospective longitudinal design, descriptive statistics, non-parametric tests and multiple linear regression analysis were used to evaluate factors associated with quality of couple relationship among first-time mothers and partners, during pregnancy and the first six months of parenthood. Results: The overall results of the thesis revealed both similarities and differences between expectant first-time mothers’ and partners’ perceptions of professional support, effects from social support and associated factors with perceived quality of couple relationship. The similarities were; both mothers and partners perceived that professional support could facilitate partner involvement, influence their couple relationship and facilitate contacts with other expectant parents. According to first-time mothers’ experiences, their couple relationship with their partner was also strengthened by social support during pregnancy. Further, the results showed that both first-time mothers’ and partners’ higher perceived couple relationship quality six months after birth, was associated with their higher perceived social support. The results showed also that both mothers and partners perceived their quality of couple relationship to decrease and Sense of Coherence to increase six months after childbirth, compared to the pregnancy. Differences revealed were such as: higher Sense of Coherence was only associated with mothers’ higher perceived quality of couple relationship, and first-time mothers reported perceiving more social support compared to the partners both during pregnancy, first week and six months after childbirth. Conclusions: Professional and social support can strengthen first-time mothers and partners both individually and as a couple, in their abilities to cope with childbearing. On the individual basis, the expectant parents could be strengthened through professional and social support that contributed to their understanding and feeling of being prepared for childbirth and parenting, for instance. As a couple, the parents were strengthened by professional support that included the partner’s role, as well as higher perceived social support overall. In contrast, lack of support could have a negative influence on the expectant parents’ feeling of being prepared for childbirth and parenting. Besides this, the results indicates that childbearing has a positive effect on parents’ abilities to cope with life even though their quality of couple relationship decrease. Professionals can use these results in their further understanding about how to offer satisfactory support to first-time mothers and partners during childbearing.

Optical coherence tomography (OCT) and Photoacoustic microscopy (PAM) are two noninvasive, high-resolution, three-dimensional, biomedical imaging modalities based on different contrast mechanisms. OCT detects the light backscattered from a biological sample either in the time or spectral domain using an interferometer to form an image. PAM is sensitive to optical absorption by detecting the light-induced acoustic waves to form an image. Due to their complementary contrast mechanisms, OCT and PAM are suitable for being combined to achieve multimodal imaging. In this dissertation, an optical coherence photoacoustic microscopy (OC-PAM) system was developed for in vivo multimodal retinal imaging with a pulsed broadband NIR light source. To test the capabilities of the system on multimodal ophthalmic imaging, the retina of pigmented rats was imaged. The OCT images showed the retinal structures with quality similar to conventional OCT, while the PAM images revealed the distribution of melanin in the retina since the NIR PAM signals are generated mainly from melanin in the posterior segment of the eye. By using the pulsed broadband light source, the OCT image quality highly depends on the pulse-to-pulse stability of the light source without averaging. In addition, laser safety is always a concern for in vivo applications, especially for eye imaging with a pulsed light source. Therefore, a continuous wave (CW) light source is desired for OC-PAM applications. An OC-PAM system using an intensity-modulated CW superluminescent diode was then developed. The system was tested for multimodal imaging the vasculature of a mouse ear in vivo by using Gold Nanorods (GNRs) as contrast agent for PAM, as well as excised porcine eyes ex vivo. Since the quantitative information of the optical properties extracted from the proposed NIR OC-PAM system is potentially able to provide a unique technique to evaluate the existence of melanin and lipofuscin specifically, a phantom study has been conducted and the relationship between image intensity of OCT and PAM was interpreted to represent the relationship between the optical scattering property and optical absorption property. It will be strong evidence for practical application of the proposed NIR OC-PAM system.

Many-core architectures provide an efficient way of harnessing the growing numbers of transistors available in modern fabrication processes; however, the parallel programs run on these platforms are increasingly limited by the energy and latency costs of communication. Existing designs provide a functional communication layer but do not necessarily implement the most efficient solution for chip-multiprocessors, placing limits on the performance of these complex systems. In an era of increasingly power limited silicon design, efficiency is now a primary concern that motivates designers to look again at the challenge of cache coherence. The first step in the design process is to analyse the communication behaviour of parallel benchmark suites such as Parsec and SPLASH-2. This thesis presents work detailing the sharing patterns observed when running the full benchmarks on a simulated 32-core x86 machine. The results reveal considerable locality of shared data accesses between threads with consecutive operating system assigned thread IDs. This pattern, although of little consequence in a multi-node system, corresponds to strong physical locality of shared data between adjacent cores on a chip-multiprocessor platform. Traditional cache coherence protocols, although often used in chip-multiprocessor designs, have been developed in the context of older multi-node systems. By redesign- ing coherence protocols to exploit new patterns such as the physical locality of shared data, improving the efficiency of communication, specifically in chip-multiprocessors, is possible. This thesis explores such a design - Proximity Coherence - a novel scheme in which L1 load misses are optimistically forwarded to nearby caches via new dedicated links rather than always being indirected via a directory structure.

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