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Without question, it is apparent that organizations are predominantly dependent on the use of computer-mediated communication (CMC) to conduct their daily operations. As a result, information is rapidly flowing throughout the workplace and being exchanged at a rate unlike ever before. Unfortunately, this rapid flow of information has increased the potential for information overload to occur among employees. Through a phenomenological based approach, this study explored the experiences of information overload that occur as a result of CMC use in the workplace, from the subjective point of view of ten participants. Findings indicated that the experiences described among these participants can be understood through the examination of four descriptive themes: Constant Communication, Unpredictability, Miscommunication, and lastly Increased Workload and Responsibilities. Furthermore, two theories: Media Richness Theory (MRT) and Social Influence Theory (SIT), served as the theoretical framework for this study.

Magister Artium (Development Studies) - MA(DVS) / The objective of this research is to investigate the factors at plant level which impact on the diffusion of Japanese Manufacturing Techniques to enterprises in developing countries generally, and South Africa specifically. This informs the development of meaningful supply-side measures to improve the competitiveness of South African manufacturers. This has been achieved through both a thorough examination of the literature and through field research. The field research documents the implementation experiences in fifteen South African plants which participated in the Shopfloor Best Practice workshops of the Manufacturing Roundtable (MRT). I chose to examine these examples of transfer as I was a participant researcher, attached to the MRT. The central question which guided my research is what are the factors which affect the depth of systemic adoption of Japanese Manufacturing Techniques on the shopfloor in South Africa, and what this indicates for the breadth of diffusion of the techniques across the manufacturing sector as a whole. The research argument is that for sustainable adoption both social and technical aspects of Japanese Manufacturing Techniques need to be addressed. Focusing on the technical aspects only and presenting a universally applicable model obscures the realities of transfer, as the embeddedness of the techniques in the social and institutional context is ignored. The point of departure for analysis in this thesis is thus real examples of transfer, as opposed to a universally defined and abstracted model. The experience and opinions of the workshop participants, and those of managers in their plants, have been gathered through individual in-depth interviews and site visits. The evidence indicates that there are many factors both internal and external to the firm which are likely to constrain significantly the ability of some firms to move in the systemic direction. These include the poor primary education of much of the workforce, poor management skills, wage and social inequality and a lack of participation in the workplace. It becomes apparent that the process of diffusion amongst South African manufacturers is not likely to be rapid or steady, and that the most likely path is one of uneven diffusion.

Research in the last decades has shown that individuals with high degrees in the personality trait of alexithymia not only have difficulties in identifying and recognizing own feelings, but also show deficits in reading emotions from facial expressions of other people. Therefore, the current dissertation investigates the neural correlates of recognizing emotional facial expressions as a function of alexithymia. Initially, a theoretical introduction is given and existing findings from behavioral as well as structural and functional neuroimaging research are presented. Open questions are identified and addressed in one structural and two functional magnetic resonance imaging studies that were compiled into three original research articles. Study 1 examined the gray matter profile of high and low alexithymic individuals in selected brain regions relevant for processing emotional faces. In Study 2, functional neuroimaging was used to investigate the neural correlates of high alexithymic individuals\'' difficulties in labeling briefly presented (≤ 100 ms) facial expressions of emotion. Study 3 investigated neural activations as a function of alexithymia during the labeling of emotional facial expressions when these are presented with little temporal constraints (≥ 1 s). The results of these studies are summarized and integrated with the existing literature. Finally, open issues are discussed and ideas for further research are outlined.

It has been known for almost two decades that the water proton NMR signal of diffusing water molecules in brain white matter undergoes a non-monoexponential decay with increasing diffusion gradient factor b. With the help of numerical simulations and analytical expressions, much effort has been directed to describing the signal decay and to extracting relevant biophysical features of the system under investigation. However, the physical basis of such nonmonoexponential behavior is still not properly understood. The primary difficulty in characterizing this phenomenon is the variation in behavior in the different directions of diffusion measurement. A combined framework that accounts for the diffusion process in all directions requires several parameters. Addition of many such parameters renders a model to be unwieldy and over-complicated, but over-simplifications can be shown to miss crucially relevant information in the data. In this thesis, I have attempted to handle this problem with simple measurements that span a wide range of parameter space. Compared to often-performed measurements that probe diffusion over a time-scale of 50-100 ms with relatively low diffusion weighting, the measurements here have been done for very short diffusion times of 2 ms and also very long diffusion times up to 2 s. The temperature dependence of the diffusion coefficients has also been extensively probed. To avoid problems related to gross tissue heterogeneity, diffusion-weighted MR imaging in vivo was performed with ultra-high resolution. These simple measurements allowed sequential assessment of many possible arguments that could have led to such non-monoexponential decay curves. Finally, it was concluded that the water in the glial processes was the major contributor to the non-exponential decay, giving rise to a \''slow\'' component both along the axonal fibers and transverse to them.

This dissertation describes the development and implementation of advanced slice-accelerated (SMS) MRI methods for imaging blood perfusion and water diffusion in the human brain. Since its introduction in 1977, Echo-Planar Imaging (EPI) paved the way toward a detailed assessment of the structural and functional properties of the human brain. Currently, EPI is one of the most important MRI techniques for neuroscientific studies and clinical applications. Despite its high prevalence in modern medical imaging, EPI still suffers from sub-optimal time efficiency - especially when high isotropic resolutions are required to adequately resolve sophisticated structures as the human brain. The utilization of novel slice-acceleration methods can help to overcome issues related to low temporal efficiency of EPI acquisitions. The aim of the four studies outlining this thesis is to overcome current limitations of EPI by developing methods for slice-accelerated MRI. The first experimental work of this thesis describes the development of a slice-accelerated MRI sequence for dynamic susceptibility contrast imaging. This method for assessing blood perfusion is commonly employed for brain tumor classifications in clinical practice. Following up, the second project of this thesis aims to extend SMS imaging to diffusion MRI at 7 Tesla. Here, a specialized acquisition method was developed employing various methods to overcome problems related to increased energy deposition and strong image distortion. The increased energy depositions for slice-accelerated diffusion MRI are due to specific radiofrequency (RF) excitation pulses. High energy depositions can limit the acquisition speed of SMS imaging, if high slice-acceleration factors are employed. Therefore, the third project of this thesis aimed at developing a specialized RF pulse to reduce the amount of energy deposition. The increased temporal efficiency of SMS imaging can be employed to acquire higher amounts of imaging data for signal averaging and more stable model fits. This is especially true for diffusion MRI measurements, which suffer from intrinsically low signal-to-noise ratios. However, the typically acquired magnitude MRI data introduce a noise bias in diffusion images with low signal-to-noise ratio. Therefore, the last project of this thesis aimed to resolve the pressing issue of noise bias in diffusion MRI. This was achieved by transforming the diffusion magnitude data into a real-valued data representation without noise bias. In combination, the developed methods enable rapid MRI measurements with high temporal efficiency. The diminished noise bias widens the scope of applications of slice- accelerated MRI with high temporal efficiency by enabling true signal averaging and unbiased model fits. Slice-accelerated imaging for the assessment of water diffusion and blood perfusion represents a major step in the field of neuroimaging. It demonstrates that cur- rent limitations regarding temporal efficiency of EPI can be overcome by utilizing modern data acquisition and reconstruction strategies.

Erst seit 2010 sind kombinierte Positronenemissionstomographie- Magnetresonanztomographie-Geräte (PET/MRT) zur hybriden Bildgebung verfügbar. Die mit der Entwicklung der Geräte verbundenen Hoffnungen bezüglich der onkologischen Diagnostik lagen zunächst auf einer verbesserten Genauigkeit in der Tumordetektion im Vergleich zur PET/CT. Rasch wurde jedoch deutlich, dass insbesondere die Möglichkeit der non-invasiven, multiparametrischen Charakterisierung von Tumorerkrankungen einen wesentlichen Vorteil der PET/MRT gegenüber der PET/CT darstellt. Der im Universitätsklinikum Leipzig AöR 2011 installierte PET/MRT-Scanner war einer der ersten weltweit und in dieser Habilitationsschrift sind die ersten Erfahrungen mit dieser Methode auf dem Gebiet der onkologischen Diagnostik zusammengefasst. Schwerpunkt ist dabei die Diagnostik von Kopf-Hals-Tumoren, da in diesem Bereich die CT aufgrund des im Vergleich zur MRT schlechteren Weichteilkontrastes Einschränkungen aufweist. In dieser Schrift werden zunächst die unterschiedlichen Konzepte im Gerätedesign der PET/MRT und die Besonderheiten der PET/MRT im Vergleich zur PET/CT erläutert. Auch die kritischen Punkte, die bei der Implementierung eines PET/MRT-Scanners zu beachten sind, werden detailliert dargestellt. Hierbei werden besonders die baulichen und organisatorischen Aspekte berücksichtigt, es werden aber auch Hinweise zur Qualitätskontrolle und zur Entwicklung von Untersuchungsprotokollen gegeben. In der ersten klinischen Studie zur Anwendung der PET/MRT mit 18F-Fluorodesoxyglucose (18F-FDG) bei Patienten mit Kopf-Hals-Tumoren konnten wir hinsichtlich Sensitivität und Spezifität noch keine Unterschiede zur PET/CT nachweisen. Allerdings war hier die untersuchte Patientengruppe heterogen und enthielt sowohl Primär- als auch Rezidivtumore. Aktuell konzentriert sich die onkologische Forschung am PET/MRT auf die Möglichkeiten der multiparametrischen Bildgebung zur Detektion und vor allem Charakterisierung von Tumorerkrankungen. Hier konnten wir signifikante Korrelationen von Glukosestoffwechsel und verschiedenen Perfusionsparametern bei Patienten mit Kopf-Hals-Tumoren nachweisen. Bei Patientinnen mit Zervixkarzinom konnte ein inverser Zusammenhang zwischen Glukosestoffwechsel und Diffusionsrestriktion nachgewiesen werden. Die letzte aufgeführte Arbeit zeigt die Korrelationen zwischen der bildgebenden Tumorcharakterisierung und histopathologischen Ergebnissen bei Kopf-Hals-Tumoren, wo wir Zusammenhänge von Kernfläche und dem Proliferationsmarker Ki-67 mit Diffusionseigenschaften bzw. Glukosestoffwechsel im Tumorgewebe nachweisen konnten.:Inhalt 1. Einführung in die Thematik 1.1. Entwicklung der hybriden Bildgebung 1.2. Technische Konzepte zur Kombination von PET und MRT 1.2.1. Separate Geräte – räumlich getrennt 1.2.2. Separate Geräte - in einem Raum kombiniert 1.2.3. Integrierte Geräte 1.3. Schwächungskorrektur 1.4. Einsatzgebiete 1.5. Untersuchungsprotokoll am PET/MRT 1.5.1. Allgemeine Überlegungen zum Untersuchungsablauf 1.5.2. MRT-Sequenzen 1.5.3. PET-Tracer 1.6. Eigene Studien 2. Originalarbeiten 2.1. Physikalische und organisatorische Maßnahmen für Installation, regulatorische Anforderungen und Implementierung eines simultanen hybriden PET/MR-Bildgebungssystems in Forschung und klinischer Versorgung 2.2. Ergebnisse der simultanen 18F-FDG PET/MRT im Vergleich zur 18F-FDG PET/CT bei Patienten mit Kopf-Hals-Tumoren 2.3. In vivo Korrelation von Glukosemetabolismus, Zelldichte und mikrozirkulatorischen Parametern bei Patienten mit Kopf-Hals-Tumoren: erste Ergebnisse von Untersuchungen mittels simultaner PET/MRT 2.4. Simultane 18F-FDG PET/MRT: Korrelation von scheinbarem Diffusionskoeffizient (ADC) und standardisiertem Aufnahmewert (SUV) beim primären und rezidivierten Zervixkarzinom 2.5. Simultane 18F-FDG PET/MRT: Assoziationen zwischen Diffusion, Glukosemetabolismus und histopathologischen Parametern bei Patienten mit Plattenepithelkarzinomen der Kopf-Hals- Region 3. Ausblick mit Übersichtsartikel „Molekulare Bildgebung bei Kopf-Hals-Tumoren“ 4. Literaturverzeichnis 5. Erklärung über die eigenständige Anfertigung der Arbeit und Kenntlichmachung der benutzten Hilfsmittel bzw. Hilfen 6. Lebenslauf 7. Danksagung

Zielstellung: Die Verwendung von Computertomographie und Magnetresonanzto-mographie zur Diagnostik von pathologischen Weichteilveränderungen, wie Läsionen der Speicheldrüsen, wird empfohlen. Diese begründet sich in Ihrer hohen Bildauflö-sung und dem guten Bildkontrast. Nach unserem Wissen gibt es aktuell keine publi-zierte Literatur, welche sich mit der CT- oder MRT-Anatomie der Speicheldrüsen der Katze beschäftigt. Ziel der vorliegenden Arbeit war es daher, Schnittbildmerkmale der Speicheldrüsen zu definieren und Landmarken für eine sichere Identifikation zu be-schreiben. Material und Methoden: Es wurden zwei Gruppen von Katzen untersucht. Die pros-pektiv untersuchten Tiere bestanden aus 16 Katzen, welche aus Gründen euthana-siert wurden, die nicht in Zusammenhang mit der Studie standen. Diese erfuhren ein CT (1 mm Schichtdicke) und 0,5 Tesla MRT (T2W, T2W SPIR, PDW, T1W) des Kop-fes. Im retrospektiven Anteil der Studie wurden CT-Untersuchungen (0,8-1 mm Schichtdicke) von 25 Katzen und MRT-Untersuchungen (T2W, T1W vor und nach Kontrastmittelgabe) von 21 Katzen verwendet. Diese Untersuchungen wurden zwi-schen 2005 und 2013 in unserer Klinik angefertigt. Dabei konnten keine Pathologien in Zusammenhang mit den Speicheldrüsen festgestellt werden. Alle Speicheldrüsen wurden bezüglich Identifizierbarkeit, Abgrenzbarkeit, Größe und Signalverhalten un-tersucht. Wenn vorhanden, wurden anatomische Landmarken die Speicheldrüsen umgebend notiert. Zusammenfassung 80 Ergebnisse: 94,3% der Glandulae parotidae, 90,7% der Glandulae mandibulares und 96,8% der Glandulae zygomaticae konnten mit dem CT identifiziert werden. Beim MRT waren es 94,1% der Glandulae parotidae, 99,2 % der Glandulae mandibulares, 88,9% der Glandulae zygomaticae und 51,4 % der Glandulae buccalis ventralis. In beiden Gruppen konnten keine der restlichen kleinen Speicheldrüsen identifiziert werden, dies galt für beide Schnittbildverfahren. Als hilfreiche anatomi-sche Landmarken konnten der äußere Gehörgang, der M. masseter, der M. pterygo-ideus medialis und der Bulbus oculi herangezogen werden. Die medianen Dichtewer-te lagen für die Glandula parotis, die Glandula mandibularis und die Glandula zygo-matica bei 65 HU, 62 HU und 57 HU. Die Parotis war überwiegend dezent hyperin-tens zur Muskulatur und hypointens zum Fett. Die Mandibularis, Zygomatica, und Glandula buccalis ventralis stellten sich hauptsächlich hyperintens zur Muskulatur und hypointens zu Fettgewebe dar. Dieses Signalverhalten war für T1W, T2W und T2W SPIR (fettunterdrückt) gewichtete Sequenzen gleich. Die Größe war für beide Gruppen und Modalitäten vergleichbar und lag bei circa 17 x 6 mm (gemessen von lateral nach medial und von dorsal nach ventral) bei der Glandula parotis, 8 x 17 mm bei der Glandula mandibularis, 10 x 7 mm bei der Glandula zygomatica und bei der Glandula buccalis ventralis 3 x 10 mm. Schlussfolgerungen: Landmarken und Aussagen über die Signalintensität bezie-hungsweise Dichte und die Größe der Glandula parotis, Glandula mandibularis, Glandula zygomatica und der Glandula buccalis ventralis konnten erhoben werden. Die mangelhafte Identifizierbarkeit der restlichen kleinen Speicheldrüsen, im Ver-gleich zu den oben genannten, kann vor allem mit dem unzureichenden Weichteil-kontrast zum umliegenden Gewebe im CT und der niedrigen Auflösung des Nieder-feld-MRTs erklärt werden. Neuere MRT-Techniken können detailliertere Bilder er-zeugen und so eine Beschreibung der kleinen Speicheldrüsen ermöglichen. / Objective: Due to their high resolution and useful contrast resolution, CT and MRI are recommended methods for diagnosing pathological changes of soft tissues such as lesions of the salivary glands. To our knowledge, no studies about the CT or MR anatomy of the feline salivary glands have been published yet. The aim of the study was to define anatomical characteristics of the salivary glands in cross-sectional im-ages and to describe landmarks for a reliable identification. Materials and methods: Two groups of cats where examined. In a prospective trial, 16 cats, euthanized for reasons unrelated to the study, underwent a head CT (1 mm slice thickness) and 0.5 Tesla MRI scans (T2W, T2W SPIR, PDW, T1W). In a retro-spective trial, the CT scans (0.8-1 mm slice thickness) of 25 cats and the MR scans (T2W, T1W, pre- and post-contrast) of 21 cats were used. These scans were per-formed at our clinic between 2005 and 2013. No signs of salivary-gland-related pa-thologies were visible. All images were reviewed with respect to the following criteria: the presence, delineation and size of the salivary glands as well as the signal intensi-ty. Anatomical landmarks surrounding the glands were also recorded. Results: 94.3% of the parotid glands, 90.7% of the mandibular glands and 96.8% of the zygomatic glands could be delineated using CT. With MRI, 94.1% of the parotid Summary 82 glands, 99.2 % of the mandibular glands, 88.9% of the zygomatic glands and 51,4 % of the ventral buccal glands could be identified. In both groups the other small salivary glands could not be visualized neither in CT nor in MRI. Anatomical landmarks such as the external ear canal, the M. masseter, the M. pterygoideus medialis and the Bulbus oculi facilitate the identification. The mean density of the parotid gland, the mandibular gland and the zygomatic gland was 65 HU, 62 HU and 57 HU, respectively. The parotid gland was mainly modestly hyperintense to muscle and hypointense to fat. The mandibular, zygomatic and ven-tral buccal glands were hyperintense to muscle and hypointense to fat. Signal intensi-ties were similar for T1W, T2W and T2W SPIR images. Sizes were comparable for both groups and modalities and measured about 17x6 mm (lateral to medial and dor-sal to ventral) for the parotid gland, 8 x 17 mm for the mandibular gland, 10x7 mm for the zygomatic gland and 3x10 mm for the ventral buccal gland. Conclusions: Landmarks were recorded and data regarding the density/signal in-tensity and the size of the parotid gland, the mandibular gland, the zygomatic gland and the ventral buccal gland could be gathered. The discrepancy between depicting the small glands and the above mentioned glands can be explained mainly by the lack of contrast to the surrounding tissue in CT and the low spatial resolution in low-field MRI. Advanced MRI techniques are expected to produce more detailed images and therefore those techniques could be used to also describe the small salivary glands.

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Neurosurgery is a demanding medical discipline that requires a complex interplay of several neuroimaging techniques. This allows structural as well as functional information to be recovered and then visualized to the surgeon. In the case of tumor resections this approach allows more fine-grained differentiation of healthy and pathological tissue which positively influences the postoperative outcome as well as the patient's quality of life. In this work, we will discuss several approaches to establish thermal imaging as a novel neuroimaging technique to primarily visualize neural activity and perfusion state in case of ischaemic stroke. Both applications require novel methods for data-preprocessing, visualization, pattern recognition as well as regression analysis of intraoperative thermal imaging. Online multimodal integration of preoperative and intraoperative data is accomplished by a 2D-3D image registration and image fusion framework with an average accuracy of 2.46 mm. In navigated surgeries, the proposed framework generally provides all necessary tools to project intraoperative 2D imaging data onto preoperative 3D volumetric datasets like 3D MR or CT imaging. Additionally, a fast machine learning framework for the recognition of cortical NaCl rinsings will be discussed throughout this thesis. Hereby, the standardized quantification of tissue perfusion by means of an approximated heating model can be achieved. Classifying the parameters of these models yields a map of connected areas, for which we have shown that these areas correlate with the demarcation caused by an ischaemic stroke segmented in postoperative CT datasets. Finally, a semiparametric regression model has been developed for intraoperative neural activity monitoring of the somatosensory cortex by somatosensory evoked potentials. These results were correlated with neural activity of optical imaging. We found that thermal imaging yields comparable results, yet doesn't share the limitations of optical imaging. In this thesis we would like to emphasize that thermal imaging depicts a novel and valid tool for both intraoperative functional and structural neuroimaging.