Input noise approximation in tracker modeling

The validity of approximating random Gaussian distributed inputs used in human response modeling by sums of discrete sine waves is studied. An ideal rectangular power density spectrum is simulated using both filtered Gaussian white noise and sums-of-discrete sine waves with three different input cutoff frequencies in the same compensatory tracking task. Resulting normalized tracking error and quality operator observations are used to investigate apparent discrepancies in human operator characteristics. Results show that discrete and continuous input tracking data compare favorable when the power in the crossover region is taken into account

Success factors for e-learning in business organizations: a qualitative study

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Information Systems and Technologies Managemente-learning has received a consistent upswing during the last years. Promising individualized and costeffective facilitation of knowledge transfer, many business organizations have already adopted elearning initiatives. Despite this importance, however, the study situation covering its success factors is fragmented. A large majority studied e-learning in the university context, while others focused on the influence of specific factors, resulting in findings that are only partially transferable. Following a natural science research approach, this study seeks to close this research gap and provide a better understanding of e-learning success in (business) organizations. By conducting extensive literature research, it first identifies the most prevalent success factors for organizational e-learning and groups them into four domains. A bibliographical analysis then unveils four potential interrelationships among these domains. Based on these findings, eight assumptions are developed and consolidated into a research model. Through a focus group study with six participants experienced in organizational elearning, the model is consequently validated. The results show that all four identified success domains and their respective success factors exert a significant influence on organizational e-learning success. In addition, three of the four identified interrelationships between these success domains are confirmed. Ultimately, the adapted success model provides an actionable and holistic reference point for e-learning decision-makers to optimize their organizational e-learning initiatives

Cortisol synthesis by primary human keratinocytes

PhDCortisol analogues have been used to treat skin disorders, such as psoriasis and atopic dermatitis, for over 50 years but the ability of normal human keratinocytes to synthesise cortisol has not been reported. Keratinocytes are capable of de novo cholesterol synthesis, they express P450 enzymes that are required for steroidogenesis and can metabolise androgens and estrogens. In addition, steroidogenic acute regulatory protein (StAR) that controls the rate determining step of acute steroidogenesis has been identified in the epidermis. The aim of this thesis was to identify de novo cortisol steroidogenesis by keratinocytes and investigate the function of cortisol in keratinocytes in vitro. Normal epidermis was shown to express three cholesterol transporters that are associated with promoting steroid synthesis; StAR was identified in the basal layer, metastatic lymph node 64 (MLN64) in the suprabasal layers and translocator protein (TSPO) was detected throughout the epidermal layers. In addition, the nuclear receptor DAX1, a negative regulator of StAR, was identified in the cytoplasm of cells that form normal epidermis. Comparatively, the expression of these proteins was altered in psoriasis and atopic dermatitis, where DAX1 was localised to the nucleus of most diseased tissue and StAR was not detected. This suggests that acute steroid synthesis is ablated in these hyperproliferative skin conditions. The ability of normal primary human keratinocytes to synthesise cortisol was investigated. Radioimmunoassay demonstrated keratinocytes were capable of de novo pregnenolone synthesis, which was promoted with the cortisol analogue dexamethasone (dex). Interestingly, 25-hydroxycholesterol, which bypasses StAR, did not further enhance steroid synthesis. This suggests that there is an alternative rate determining step of steroid synthesis in cultured primary keratinocytes. Thin layer chromatography demonstrated keratinocytes could metabolise pregnenolone to progesterone and progesterone to cortisol. Progesterone metabolism to cortisol was also confirmed with liquid chromatography/mass spectroscopy. 3 Dex was shown to maintain keratinocyte viability and was implicated in promoting cellular redox potential. Since redox potential is a critical regulator of steroidogenesis, this observation could provide a mechanism for dex-induced pregnenolone synthesis in cultured keratinocytes. These observations led to a hypothesis that local cortisol synthesis functions to regulate cellular redox potential to prevent cell death as part of a positive feedback system. Therefore, this thesis has identified the cortisol steroidogenic pathway in primary human keratinocytes and a potential functional mechanism for the pathway

An Historical Examination Into Baptismal Usage in the Reformed Church of Scotland

Abstract Not Provided

Contactless 2-dimensional laser sensor for 3-dimensional wire position and tension measurements

We have developed a contact-free 2-dimensional laser sensor with which the position of wires can be measured in 3 dimensions with an accuracy of better than 10 micrometer and with which the tension of the wires can be determined with an accuracy of 0.04 N. These measurements can be made from a distance of 15 cm. The sensor consists of commercially available laser pointers, lenses, color filters and photodiodes. In our application we have used this laser sensor together with an automated 3 dimensional coordinate table. For a single position measurement, the laser sensor is moved by the 3-dimensional coordinate table in a plane and determines the coordinates at which the wires intersect with this plane. The position of the plane itself (the third coordinate) is given by the third axis of the measurement table which is perpendicular to this plane. The control and readout of the table and the readout of the laser sensor were realized with LabVIEW. The precision of the position measurement in the plane was determined with wires of 0.2 mm and 0.3 mm diameter. We use the sensor for the quality assurance of the wire electrode modules for the KATRIN neutrino mass experiment. We expect that the precision is at least comparable or better if the wires are thinner. Such a device could be well suited for the measurement of wire chamber geometries even with more than one wire layer.Comment: 15 pages, 8 figure