L’activité plaquettaire joue un rôle clé dans la physiopathologie de l’infarctus du myocarde avec sus-décalage du segment ST (IDM ST+). La réactivité plaquettaire est augmentée lors d’un IDM ST+, traité par angioplastie primaire ou par fibrinolyse avec succès. La relation entre la réactivité plaquettaire résiduelle après un pré-traitement, la charge athérothrombotique et la qualité de la reperfusion myocardique reste peu décrite dans le cadre des IDM ST+. La tomographie par cohérence optique et celle plus récente par domaine de fréquence offrent une imagerie de haute résolution permettant l’identification et la quantification précise de la charge athérothrombotique intracoronaire (CAT). La CAT résiduelle intra-stent peut aider à mieux comprendre la relation entre la réactivité plaquettaire et la reperfusion. Dans un premier temps, nous avons évalué la précision des tests VerifyNow et PFA en comparaison à l’agrégométrie optique pour la détection de l’hyperréactivité plaquettaire dans le contexte particulier des IDM ST+ traités par fibrinolyse avec succès. Nous avons aussi décrit les caractéristiques de la CAT avant et après angioplastie selon la présence d’une rupture de plaque ou d’une érosion coronaire chez des patients traités par fibrinolyse avec succès. Ensuite, nous avons étudié la relation entre la réactivité plaquettaire résiduelle (en réponse au ticagrelor et à l’aspirine) mesurée par VerifyNow et la reperfusion myocardique chez des patients traités par angioplastie primaire. En parallèle, nous avons décrit la relation entre la reperfusion myocardique et la CAT résiduelle intra-stent dans la même cohorte. / Platelet activity plays a key role in the pathophysiology of ST-segment elevation myocardial infarction (STEMI). Platelet reactivity is enhanced after STEMI treated with primary percutaneous coronary intervention (PCI) or successful thrombolysis. The relationship between residual platelet reactivity after pre-treatment, the atherothrombotic burden and the quality of reperfusion remains poorly described in STEMI. Optical coherence tomography (OCT) and optical frequency domain imaging (OFDI) provide high resolution imaging allowing identification and accurate quantification of intracoronary atherothrombotic burden (ATB). Residual in-stent ATB may help to better understand the relation between platelet reactivity and reperfusion. First, we assessed the accuracy of the point-of-care tests VerifyNow and PFA in comparison to light transmittance aggregometry to detect high on-treatment platelet reactivity (HPR) in the particular setting of STEMI successfully treated with fibrinolysis. We also described the characteristics of ATB before and after PCI according to the underlying presence of rupture or erosion in patients successfully treated with fibrinolysis. Then, we assessed the relationship between residual platelet reactivity (in response to ticagrelor and aspirin) using VerifyNow and myocardial reperfusion in primary PCI patients. In parallel, we studied the relationship between myocardial reperfusion and residual in-stent ATB in the same cohort.

Universities in Zimbabwe have universally adopted a full-year integrated undergraduate student workplace-based learning pedagogy following the precedent set in 1991 by one pioneering university, the National University of Science and Technology. In this explorative study I analyse participants’ views, reflections and understanding of how the full-year model of workplace-based learning enhances quality academic practices and impacts on short, medium and long-term visions and opportunities for students and other stakeholders. I employed the embedded concurrent mixed methods research design (Creswell&Clark, 2007) using interviews with lecturers, university administrators and industry supervisors, as well as open-ended questions in three matched versions of a questionnaire to students, lecturers and industry supervisors respectively. The same questionnaire provided quantitative data that was statistically analysed. Interviews were conducted with 24 participants from the university under study, industry and other universities, while 363 university students, 40 NUST lecturers and 34 industry supervisors responded to the respective questionnaires. Students, lecturers and industry supervisors concurred on the coherence between industry experiences and university learning, the beneficial experiences at the workplace, and the relevance of those experiences to society, confirming the expressed view that industry-based learning promoted quality learning and teaching, and enabled students to become work-ready. However there were perceptions of inadequate student supervision and assessment, unsatisfactory student welfare safeguards, inadequate research enthusiasm among lecturers, and the lack of involvement of the whole spectrum of industry categories. There was an underlying regard for lifelong learning enabling societal transformation into the increasingly dominant industrialised culture. Lecturers indicated an appreciation for a holistic orientation to teaching and learning (Taylor, 2009), and were inclined towards adopting the hermeneutic approach to education (Danner, 2002). It is recommended, among other things, to revitalise effective practices through staff development efforts, increasing student knowledge and empowerment, and strengthening collaborative platforms between the university and its industry partners. Chief among the suggestions for future research is the understanding and promotion of student welfare during their placement in the workplaces. / Thesis (PhD)--University of Pretoria, 2012. / Science, Mathematics and Technology Education / unrestricted

La technique de l'interférométrie en astronomie permet d'observer des objets avec une haute résolution angulaire comparativement à l'utilisation d'un unique télescope. L'observation dans l'infrarouge moyen représente aujourd'hui un enjeu en interférométrie notamment pour l'étude des noyaux actifs de galaxie ou de la formation des planètes. Cependant ce domaine spectral est particulièrement contraignant puisqu'il est soumis à l'émission propre des éléments optiques de l'instrument mais également de l'atmosphère. Ce manuscrit développe les travaux effectués sur un nouvel instrument utilisant un processus de conversion de fréquence pour transposer le rayonnement infrarouge vers un domaine spectral permettant de s'affranchir de l'émission propres des optiques. Un prototype fonctionnant dans le proche infrarouge à 1,55 µm et convertissant, via une processus de somme de fréquences, le rayonnement dans le domaine visible autour de 630 nm grâce à une pompe intense à 1064 nm, a été mis en place pour démontrer, en laboratoire, le principe de cette solution innovante notamment dans le cadre de l'analyse de la cohérence spatiale d'un corps noir. L'objectif est maintenant de démontrer la capacité de l'instrument à détecter un objet réel. J'introduis dans cette thèse les notions théoriques essentielles à la compréhension des travaux présentés pour ensuite détailler le fonctionnement de l'instrument et les éléments d'amélioration apportés, notamment en terme de transmission, au cours de ma thèse. Les études préliminaires en laboratoire du comportement de l'instrument ont permis d'aboutir aux premières franges sur le ciel en utilisant la plus petite base (34 m) du réseau interférométrique CHARA et de rechercher la magnitude limite de l'instrument. L'utilisation du processus de conversion de fréquence a pour conséquence de filtrer le spectre converti. Ainsi dans la configuration actuelle de l'interféromètre, seul 0,6 nm du spectre infrarouge en entrée du cristal est converti à travers le processus de SFG. Afin d'augmenter la sensibilité, une solution est de créer plusieurs processus de SFG simultanément dans chaque étage de conversion afin d'échantillonner le spectre infrarouge converti. Cette solution requiert d'utiliser plusieurs sources de pompe indépendantes qui vont créer des systèmes de franges incohérents. Je présente l'analyse de la cohérence temporelle d'une source infrarouge large bande convertie via l'utilisation de deux sources de pompe et un moyen de synchroniser les différents systèmes de franges afin de maximiser le contraste. / Interferometry is an instrumental technique suitable to perform astronomical observations at high angular resolution. Currently, the mid-infrared spectral domain is a real issue for the astronomical interferometry to characterize astronomical objects such as proto-planetary discs or active galactic nuclei. However, this spectral domain is subject to a large thermal background emission from the instrument and from the sky. This manuscript describes an innovative instrument using a nonlinear process of sum frequency generation to convert the mid-infrared radiation to a shorter wavelength domain where the thermal emission from the instrument is negligible. A prototype operating in the near-infrared at 1.55 µm and converting the radiation in the visible domain at 630 nm thanks to a strong pump at 1064 nm has already demonstrated its ability to analyse spatial coherence of a blackbody source. The present goal is to demonstrate its ability to detect an object on the sky. In this manuscript I introduce theoritical concepts necessary for an understanding of the overall operation of the instrument. Then, I describe the main improvements provided in this thesis, in particular concerning the instrumental transmission. The preliminary studies of the instrument operation resulted in the first on-sky fringes on the CHARA array and enabled to determine its limiting magnitude. The upconversion process acts as a filter on the converted spectrum. In the current instrumental configuration, only 0.6 nm of the input infrared spectrum is converted through the SFG process. For the purpose of increasing the instrumental sensitivity, we propose to sample the infrared spectrum by using several independent pump laser lines thus creating different incoherent fringe patterns. I present the temporal coherence analysis of a broadband infrared source converted by a dual-line pump laser and a method to synchronize the different fringe patterns to insure a maximum value of the contrast.

This study is about the upcoming challenge Sweden face with a population that grows older and in need of elderly care. The challenge lies in that municipality, as it is today, won’t have the personnel to care for the elders. The study presents two problematic factors that need change for the municipality to be able to guarantee reasonable living standards according to social laws. The first factor is the decreasing profession attractiveness that makes it hard to employ personnel. The second factor, which the study focuses on, is the fact the caregivers are overrepresented in the social insurance office statistics of personnel on sick leave. We choose to focus on the caregiver’s work environment to get a perspective on the problem. To be more exact the study focuses on finding a covariance between experienced New Public Management and Sense of coherence. Our second focus is to see if there is an underlying relation between the experienced New Public Management reforms and the three parts of Sense of coherence; meaningfulness, comprehensibility and manageability. A third focus is to see if the relationship is influenced by the caregivers’ age and work experience. Our main findings are that experienced New Public Management has both positive but mainly negative effect on caregivers’ sense of coherence and therefore on caregiver’s health. Our conclusion is therefore that New Public Management can be seen as a factor for care givers high ratings in the social security offices statistics over sick leave from work.

Cette thèse s'articule autour de l'étude de la cohérence de la lumière produite à partir de sources de paires de photons intriqués et de micro-lasers. Nous avons produit et manipulé des états photoniques intriqués, et conduit des investigations à la fois fondamentales et appliquées. Les deux études menées sur les aspects fondamentaux de la non localité avaient pour but de relaxer partiellement deux contraintes sur lesquelles s'appuie l'inégalité de Bell standard en vue d'applications à la cryptographie quantique. Ainsi, en collaboration avec l'Université de Genève, nous avons redéfini la notion de localité en prenant en compte les influences sur les mesures de corrélations des choix des configurations expérimentales et d'une efficacité globale de détection limitée. Cela a permis de définir des inégalités de Bell généralisées et les violations expérimentales qui en découlent permettent d'attester de la non localité des états quantiques observés. Nous avons aussi étudié et mis en place une solution expérimentale autorisant l'émission de photons intriqués dans des pairs de canaux télécoms pour la cryptographie quantique. Nous avons montré la préservation de l'intrication sur 150 km et obtenu des débits records en comparaison avec les réalisations similaires. Enfin, nous avons étudié les propriétés de l’émission de lasers à semi-conducteurs aux dimensions réduites. L’émission de ces composants microscopiques s'accompagne de grandes fluctuations en intensité lorsque ceux-ci sont pompés en-dessous du seuil laser. Cette étude a permis de mieux comprendre comment se construit la cohérence laser dans ces systèmes. / In this thesis we study the coherence of light emitted by entangled photon-pair sources and micro-lasers. We have generated an manipulated entangled photonic states and investigated both fundamental (non locality) and applied (quantum cryptography) research directions. The objective of two fundamental studies on non locality was to partially relax the strong assumptions on which standard Bell tests rely. To this end, we redefined, in collaboration with the University of Geneva, the formalism of locality taking into account the influence, on correlation measurements, of the freedom of choice (in the basis settings) and of the limitation of the overall detection efficiency. Both assumptions allow devising generalized Bell inequalities whose experimental violations indicate that we can still attest for non locality for the observed states. In addition, we have studied and realized an experimental setup allowing to distribute entangled photon pairs in paired telecom channels for high bit rate quantum cryptography. We have shown that entanglement is preserved over a distance of 150 km with record rates for similar realizations, by mimicking classical network solutions exploiting, in an optimal fashion, the capacity of an optical fiber link via dense spectral multiplexing. Finally, we have studied the properties of light emitted by semiconductor lasers showing reduced dimensionality. This micro-lasers actually provide output light under high intensity fluctuations when they are pumped below the threshold. Their study allowed to refine our understanding on how the coherence builds up in these systems as the cavity is filled with photons.

Die vorliegende Arbeit behandelt den Einfluss eines Defekt-induzierten, intrinsischen, statischen Unordnungspotentials innerhalb einer planaren, ZnObasierten Mikrokavität (MK) auf die lokale Dichteverteilung eines darin erzeugten, dynamischen Exziton-Polariton Bose-Einstein-Kondensats (BEK). Dies ist von Interesse, da die derzeitigen, z.B. GaN- oder ZnO-basierten MK, welche die Erzeugung von Exziton-Polariton BEKs bei Raumtemperatur ermöglichen und daher für zukünftige Anwendungen in realen Bauelementen geeignet erscheinen, durch eine hohe Defektdichte gekennzeichnet sind. Mit Hilfe eines eigens dafür aufgebauten Michelson-Interferometers wurde die Kohärenzzeit des Exziton-Polariton BEKs ermittelt, welche die Lebenszeit der einzelnen, unkondensierten Polaritonen um einen Faktor 140 übersteigt. Somit konnte das untersuchte, quantenmechanische System als zeitlich koh ärentes Kondensat identifiziert werden, da die Kohärenz während des stetigen Zerfalls und der Neubildung der einzelnen Polaritonen erhalten bleibt. Weiterhin wurden durch Unordnung hervorgerufene Dichtefluktuationen innerhalb des Polariton-Kondensats untersucht, welche in Form von Intensitäts- Fluktuationen in der Fernfeldverteilung der BEK-Emission beobachtet wurden. Dazu wurde der experimentelle Datensatz einer anregungsleistungsabhängigen Photolumineszenzuntersuchung analysiert. Dabei wurde festgestellt, dass die beobachteten Intensitätsfluktuationen über einen großen Anregungsleistungsbereich stabil bleiben, und zwar bis zum 20-fachen Wert der Schwellenleistung, welche für die Erzeugung des Polariton-BEKs nötig ist. Dies deutet auf eine gleichbleibende, durch Unordnung hervorgerufene, lokale Dichtevariation des BEKs trotz steigender Gesamtteilchendichte hin, was im starken Widerspruch zum theoretisch vorausgesagtem und experimentell gefundenem Verhalten von Kondensaten im thermischen Gleichgewicht steht. Die hier vorliegenden experimentellen Befunde konnten anhand eines Vergleichs mit numerischen Simulationen, basierend auf einem neu entwickelten theoretischem Modell, auf das Zusammenspiel des vorliegenden Unordnungspotentials und des Nicht-Gleichgewichtscharakters der untersuchten Exziton-Polariton Kondensate zurückgeführt werden. Dies verursacht dichteunabhängige Phasenfluktuationen innerhalb des Kondensats, welche die beobachteten Fluktuationen in der Fernfeldverteilung der Emission hervorrufen.:1 Introduction 1 2 Physical Basics 9 2.1 Distributed Bragg Reflectors (DBRs) . . . . . . . . . . . . . . . 10 2.2 Microcavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.3 Light-Matter-Coupling . . . . . . . . . . . . . . . . . . . . . . . 14 2.3.1 Weak Coupling Regime (WCR) . . . . . . . . . . . . . . 15 2.3.2 Strong Coupling Regime (SCR) . . . . . . . . . . . . . . 16 2.4 Bose-Einstein Condensation . . . . . . . . . . . . . . . . . . . . 19 2.4.1 Mean-Field Description . . . . . . . . . . . . . . . . . . . 21 2.4.2 Review of Research on Disorder Effects on Polariton Condensates . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.5 Coherence Properties . . . . . . . . . . . . . . . . . . . . . . . . 29 2.5.1 Ideal Light Source . . . . . . . . . . . . . . . . . . . . . 30 2.5.2 Real Light Source . . . . . . . . . . . . . . . . . . . . . . 33 2.5.3 Wiener-Khinchin Theorem (WKT) . . . . . . . . . . . . 36 I Experimental Observations 39 3 The ZnO-based Microcavity - Review of the known Properties 41 3.1 Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 3.1.1 Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . 42 3.1.2 Microstructure . . . . . . . . . . . . . . . . . . . . . . . 44 3.2 Bose-Einstein Condensation of Exciton-Polaritons . . . . . . . . 45 3.3 Conclusion and remaining Problems . . . . . . . . . . . . . . . . 52 4 Coherence Spectroscopy 53 4.1 Micro-Photoluminescence Setup . . . . . . . . . . . . . . . . . . 53 i 4.1.1 Excitation Sources . . . . . . . . . . . . . . . . . . . . . 57 4.1.2 Detection Units . . . . . . . . . . . . . . . . . . . . . . . 58 4.2 Michelson Interferometer . . . . . . . . . . . . . . . . . . . . . . 60 4.2.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . 60 4.2.2 Determination of First Order Correlation Function . . . . 62 4.3 Performance of the Interferometer . . . . . . . . . . . . . . . . . 66 5 Experimental Characterization of Bose-Einstein Condensates 69 5.1 Threshold Power Density for Polariton Condensation . . . . . . 70 5.2 Determination of Coherence Time . . . . . . . . . . . . . . . . . 78 5.3 Inhomogeneous Emission Profile . . . . . . . . . . . . . . . . . . 85 5.3.1 Analysis of individual Energy Branches . . . . . . . . . . 85 5.3.2 Origin of disorder potential . . . . . . . . . . . . . . . . 93 5.4 Summary of Experimental Results . . . . . . . . . . . . . . . . . 102 II Theoretical Predictions 105 6 Disorder Effects on an equilibrium BEC 109 7 Overview of the Theoretical Analysis of quasi-equilibrium and non-equilibrium BEC 113 7.1 Model for extended Gross-Pitaevskii equation including Gain and Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 7.2 Disorder Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 8 Numerical Simulations 125 8.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 8.2 Choice of Parameters . . . . . . . . . . . . . . . . . . . . . . . . 126 8.3 Results for both Scenarios . . . . . . . . . . . . . . . . . . . . . 130 8.4 Comparison with Experimental Data . . . . . . . . . . . . . . . 132 9 Summary of Part II 139 III Summary and Outlook 141 A Appendix 149 A.1 Alignment Procedure for the Michelson Interferometer . . . . . 149 A.2 Performance of the Interferometer . . . . . . . . . . . . . . . . . 152 A.2.1 Methods and Concepts . . . . . . . . . . . . . . . . . . . 153 A.2.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 A.2.3 Impact of Experimental Artifacts . . . . . . . . . . . . . 175 A.3 Impact of Noise on the evaluated Visibility . . . . . . . . . . . . 182 A.4 FFT Analysis of Far-Field BEC Emission Pattern . . . . . . . . 185 Acknowledgement 203 Curriculum vitae 205 declaration 206 List of own and contributed articles 207

The phenomena of coherence and localization have gained enormous research interest during the past decades. Theoretical predictions of localization have been confirmed recently in a variety of experiments in the fields of condensed matter physics and optics. We consider the widely employed model of the one-dimensional discrete nonlinear Schrödinger equation which allows for the investigation of localization of linear and nonlinear waves. We establish a generic connection between coherence and localization by showing that localized solutions are necessarily coherent. The effects of a loss of coherence are investigated numerically by applying random dephasing. The onset of a diffusive spreading regime is observed as a generic feature for persistent dephasing, which eventually destroys localization. After finite integration times maximal delocalization is achieved for a certain rate and strength of dephasing, resulting from the competition between destroying the initial wave packet on the one hand and not suppressing spreading too much on the other. When dephasing is switched off at a certain time, a loss or gain of coherence in linear wave packets directly corresponds to delocalization or stronger localization. This leads to stable partially coherent wave packets. In contrast, localization of nonlinear waves after dephasing is connected to the efforts of establishing complete coherence, at least for asymptotically long times. On intermediate time scales, however, various interesting partially coherent regimes can be observed. / Die Phänomene von Kohärenz und Lokalisierung haben sich in den letzten Jahrzehnten zum Schwerpunkt zahlreicher Forschungsinteressen entwickelt. Erst kürzlich wurden theoretische Vorhersagen von Lokalisierung in verschiedensten Experimenten in den Bereichen der Festkörperphysik und Optik bestätigt. In dieser Arbeit wird das häufig angewendete Modell der eindimensionalen diskreten nichtlinearen Schrödingergleichung betrachtet, welches die Untersuchung der Lokalisierung von linearen und nichtlinearen Wellen ermöglicht. Eine generelle Verbindung zwischen Kohärenz und Lokalisierung wird gezeigt, wonach lokalisierte Lösungen notwendigerweise kohärent sind. Die Auswirkungen eines Verlustes von Kohärenz werden numerisch durch Anwendung unterschiedlicher Methoden eines zufälligen Dephasierens untersucht. Ein permanentes Dephasieren führt stets zum Auftreten eines diffusiven Regimes, welches letztlich die Zerstörung von Lokalisierung bedingt. Nach einer endlichen Integrationszeit wird jedoch eine maximale Delokalisierung nur durch eine bestimmte Rate und Stärke des Dephasierens bewirkt, resultierend aus einem Wettstreit zwischen möglichst schneller Zerstörung des ursprünglichen Wellenpaketes auf der einen Seite und nicht zu starker Behinderung des Zerfließens auf der anderen. Wird das Dephasieren nach einer bestimmten Zeit abgeschaltet, so entspricht ein folglicher Verlust oder Zugewinn an Kohäarenz in einem linearen Wellenpaket direkt einem Verlust oder Zugewinn von Lokalisierung. Dabei treten im allgemeinen stabile teil-kohärente Wellenpakete auf. Im Gegensatz dazu ist Lokalisierung nichtlinearer Wellenpakete stets mit den Bemühungen verbunden, vollständige Kohärenz wiederherzustellen, zumindest für asymptotisch lange Zeiten. Auf mittleren Zeitskalen können jedoch verschiedene interessante teil-kohärente Strukturen beobachtet werden.

While dental caries represents the major chronic disease of humans, visual and tactile inspection are the methods of choice in daily dental practice. Several optical technologies have been developed in recent years for the purpose of dental examination, including near-infrared light transillumination as a promising tool for the supplementation and partial replacement of radiography. In case of occlusal alterations, the incidence of surface discolorations impedes the visual assessment, whereas tactile inspection appears to yield little diagnostic information or might be detrimental. Optical coherence tomography (OCT) facilitates depth-resolved imaging with μm resolution, utilizing near-infrared light, and has already shown its potential for various dental applications. We have recently demonstrated that depolarization imaging utilizing the degree of polarization uniformity (DOPU) extends those abilities by the detection of early carious lesions, as it provides an unambiguous demineralization contrast. Here, we show that this approach also enables the assessment of occlusal enamel lesions in the presence of stains, and compare PS-OCT cross sections with polarized light microscopy (PLM) images of thin sections. For tooth samples with discoloration or demineralization, respectively, PS-OCT and PLM results are in good agreement.

The present thesis analyses the paragraph structuring of non-literary texts in Czech and Spanish and in translations from Spanish into Czech. Paragraph has been defined as a textual and cognitive unit, which is characterized by a unity of topic and inner coherence and plays an important role in text production and interpretation. The central part of the thesis presents the results of an empirical analysis of three groups of non-literary texts consisting in a three-stage comparison of comparable and parallel texts. The first aim of the analysis is to detect whether there are any culture-bound differences in paragraph length and thematic structure between comparable Spanish and Czech texts. The quantitative analysis was also focused on average length of sentences. The second aim is to describe the translators' approach by comparing the translations with their respective originals. Subsequently, the translations were compared with comparable original Czech texts. Based on this comparison it has been determined to what extent the translations are oriented towards the pole of adequacy (reflecting the values of the source language), or on the contrary, towards the pole of acceptability (reflecting the values of the target language). A translation analysis attempts to describe the factors influencing the...

Systems for high performance computing are getting increasingly complex. On the one hand, the number of processors is increasing. On the other hand, the individual processors are getting more and more powerful. In recent years, the latter is to a large extent achieved by increasing the number of cores per processor. Unfortunately, scientific applications often fail to fully utilize the available computational performance. Therefore, performance analysis tools that help to localize and fix performance problems are indispensable. Large scale systems for high performance computing typically consist of multiple compute nodes that are connected via network. Performance analysis tools that analyze performance problems that arise from using multiple nodes are readily available. However, the increasing number of cores per processor that can be observed within the last decade represents a major change in the node architecture. Therefore, this work concentrates on the analysis of the node performance. The goal of this thesis is to improve the understanding of the achieved application performance on existing hardware. It can be observed that the scaling of parallel applications on multi-core processors differs significantly from the scaling on multiple processors. Therefore, the properties of shared resources in contemporary multi-core processors as well as remote accesses in multi-processor systems are investigated and their respective impact on the application performance is analyzed. As a first step, a comprehensive suite of highly optimized micro-benchmarks is developed. These benchmarks are able to determine the performance of memory accesses depending on the location and coherence state of the data. They are used to perform an in-depth analysis of the characteristics of memory accesses in contemporary multi-processor systems, which identifies potential bottlenecks. However, in order to localize performance problems, it also has to be determined to which extend the application performance is limited by certain resources. Therefore, a methodology to derive metrics for the utilization of individual components in the memory hierarchy as well as waiting times caused by memory accesses is developed in the second step. The approach is based on hardware performance counters, which record the number of certain hardware events. The developed micro-benchmarks are used to selectively stress individual components, which can be used to identify the events that provide a reasonable assessment for the utilization of the respective component and the amount of time that is spent waiting for memory accesses to complete. Finally, the knowledge gained from this process is used to implement a visualization of memory related performance issues in existing performance analysis tools. The results of the micro-benchmarks reveal that the increasing number of cores per processor and the usage of multiple processors per node leads to complex systems with vastly different performance characteristics of memory accesses depending on the location of the accessed data. Furthermore, it can be observed that the aggregated throughput of shared resources in multi-core processors does not necessarily scale linearly with the number of cores that access them concurrently, which limits the scalability of parallel applications. It is shown that the proposed methodology for the identification of meaningful hardware performance counters yields useful metrics for the localization of memory related performance limitations.