The in-vitro culture of human embryonic stem and keratinocyte cells has great potential to revolutionise the therapeutics industry. Indeed it is hoped that these cells will provide a superior alternative to current tissue and organ transplantation. However, both of these cell types require animal and/or donor products for their successful maintenance in-vitro. This requirement results in a significant risk of cross contamination from the animal or donor products to either the primary keratinocyte or hES cells. These potentially transplantable cells therefore need to be cultured in an environment free from animal or donor products to remove the risk of contamination to the patient. The ideal growth conditions must comprise of two attributes; firstly they must be free from animal or donor products, and secondly the culture system must be fully defined. Recently, it was discovered that an extra-cellular matrix protein, vitronectin, could be used in conjunction with growth factors and growth factor-binding proteins (VN:GF combination), to promote enhanced cell migration and growth through the co-activation of integrin and growth factor receptors. Given that growth factors and serum are clearly important in supporting the in-vitro cultivation of mammalian cells, and that vitronectin is an abundant protein in serum, I hypothesised that these VN:GF combinations could be translated into a serum-free medium that would support the serial propagation and self renewal of primary keratinocytes and hES cells. As reported in this thesis I have developed a defined, serum-free media for the culture of these cells that incorporates the VN:GF combinations. While the two media differ slightly in their compositions, both support the serial, undifferentiated expansion of their respective cells types. Together, this represents a significant advance that will ultimately facilitate the therapeutic use of these cells. However, the in-vitro expansion of these cells in these new media still required the presence of a feeder cell layer. In view of this I aimed to explore the in-vitro micro-environment of primary keratinocytes using a novel proteomic approach in an attempt to find candidate factors that could be used in conjunction with the VN:GF media to replace both serum and the feeder cells. The proteomic approach adopted examined the secretion of proteins into the defined, minimal protein content VN:GF media when the feeder cells were cultured alone, as well as in co-culture with primary keratinocytes. This strategy allowed assessment of proteins/factors that are secreted in response to both autocrine and paracrine cellular interactions and revealed a number of candidate factors that warrant further investigation. Ultimately this proteomic information and the associated new insights into the keratinocyte in-vitro culture microenvironment may lead to the development of a culture system for these cells that is not reliant on either a feeder cell layer or serum for their successful propagation. Moreover, it is likely that this will also be relevant to the feeder cell-free propagation of hES cells. This has obvious advantages for the culture of primary keratinocytes and hES cells in that it will allow a safe defined culture system for the undifferentiated propagation of these cells. This will facilitate the generation of cells and tissues free from xenogeneic and allogeneic contaminants, thus ensuring any therapeutics developed from these cell types are approved for therapeutic applications and importantly, will minimise risks to patients.

The main research question of this thesis is &ldquo / How can HES (small scale hydroelectricity plant) opposition be analyzed in terms of social ecology?&rdquo / A second research question is raised to answer first one as &ldquo / How can any environmental action be analyzed in terms of social ecology?&rdquo / About ecological crisis, Murray Bookchin&rsquo / s social ecology develops strong criticism against liberal environmentalism, deep ecology and Marxism and provides an alternative radical social change as Libertarian Municipalism (LM). Social ecology criticizes environmentalism as legitimizing current status quo destroying nature and offers ecological approach for real solution. LM movement is a political program of social ecology to reach rational, ecological and democratic society that is domination free and so does not dominate nature. I developed a LM movement model from Janet Biehl&rsquo / s study and integrated this model into George Pepper&rsquo / s classification of environmentalism to reach a Classification Table (CT) that is based on social ecological principles. CT is an attempt to develop a tool to analyze all sorts of environmental activities according to social ecology. Implementation of CT at field study shows HES opposition has the desire of strict state controls and planning as significant aspects of welfare-liberal environmentalism. On the other hand, the common critique of central, urban, professional and fund dependent environmentalism of national ENGOs fits market-liberal environmentalism critique of LM model. The increasing demand to join decision-making mechanism, the bottom-to-top regional organization of local platforms and &ldquo / living space&rdquo / discourse show LM tendency. In fact, HES threat ignites participation demands of local people in Turkey.

In einer kontrollierten Studie an gesunden Pferden wurde die Pharmakokinetik von Infukoll HES 10% untersucht und dessen klinische Wirksamkeit in unterschiedlichen Dosierungen mit der von isotoner und hypertoner NaCl-Lösung verglichen. In einer darauffolgenden prospektiven klinischen Untersuchung an Pferden mit akuter Kolitis oder Ileus konnte die Wirksamkeit des Plasmaexpanders am Pferdepatienten dokumentiert werden. Die Versuchsgruppe, bestehend aus 6 Warmblut-Stuten, nahm an 5 Versuchsreihen teil und erhielt jeweils als einmalige i.v. Bolusinfusion Infukoll HES in der Dosierung von 5 ml/kg KM (Reihe 1), 10 ml/kg KM (Reihe 2) und 15 ml/kg KM (Reihe 3) sowie isotone NaCl-Lösung (15 ml/kg KM &#150; Reihe 4) und hypertone NaCl-Lösung (7,5%ig; 4 ml/kg KM &#150; Reihe 5). Die Patienten wurden in 3 Gruppen unterteilt: Pferde mit akuter Kolitis (Gruppe 1; n=8), Pferde mit Dünndarmileus (Gruppe 2; n=7) und Pferde mit Dickdarmileus (Gruppe 3; n=9). Alle Patientengruppen erhielten zunächst eine i.v. Bolusinfusion, bestehend aus 10 ml isotoner NaCl-Lösung/kg KM und 10 ml Infukoll HES/kg KM. Anschließend wurde die Infusionstherapie mit isotoner NaCl-Lösung (4 ml/kg/h DTI) fortgeführt. Blutentnahmen erfolgten bei gesunden und kranken Pferden vor der Bolusinfusion sowie 10 Minuten, 1, 2, 4, 6, 8, 10, 12 und 24 Stunden danach. Zu allen Messzeitpunkten wurde ein Blutbild angefertigt und die Konzentration von GEW und Albumin im Serum ermittelt. In größeren Abständen erfolgte die Bestimmung der Amylaseaktivität und der Konzentrationen von Glukose, Harnstoff sowie Kreatinin. Ausschließlich bei der Versuchsgruppe wurde zusätzlich die HES-Konzentration im Serum über 24 Stunden sowie Harnparameter (Dichte, GGT-Kreatinin-Verhältnis, Fraktionelle Exkretion von Na, K, und P) innerhalb der ersten 4 Stunden nach der Bolusinfusion bestimmt. In der Versuchsgruppe war die Infusion mit Infukoll HES, gemessen an den Dilutionsparametern Hämatokrit, Hämoglobin, GEW und Albumin, in jeder der verwendeten Dosierung signifikant volumenwirksamer als isotone und hypertone NaCl-Lösung. Es konnte keine klinisch relevante Beeinflussung der Nierenfunktion beim nierengesunden Pferd nachgewiesen werden. Die Infusion von Infukoll HES führt zu einer dosisabhängigen und dilutionsbedingten Verlänge-rung der APTT; die Beeinflussung durch die verwendeten Dosierungen darf als klinisch irrelevant bezeichnet werden. HES verhält sich beim Pferd im wesentlichen wie beim Menschen. Sie zeigt eine lineare Pharmakokinetik und verteilt sich fast ausschließlich intravasal. Es konnte erstmals nachgewiesen werden, dass auch beim Pferd ein signifikanter und dosisabhängiger Anstieg der Serumamylaseaktivität nach der Infusion mit HES erfolgt. In den Patientengruppen führte die Bolusinfusion mit Infukoll HES zu einer signifikanten Verbesserung des Hydratationszustandes und der Herz-Kreislauf-Funktion. Die Nierenfunktion wurde nachhaltig verbessert, trotz einer vorübergehenden, nicht signifikanten Erhöhung der Harnstoff-Konzentration im Serum. Eine Verlängerung der APTT wurde eine Stunde nach der Infusion mit HES beobachtet. Beide Parameter waren bei der Mehrzahl aller Patienten bereits zum Zeitpunkt der Erstuntersuchung pathologisch erhöht. Bereits zu diesem Zeitpunkt korrelierten APTT und Herzfrequenz hochsignifikant mit dem späteren Überleben der Patienten (p<0,01). Die Amylase verhielt sich wie bei den Versuchstieren und stieg signifikant an. Bei 6/24 (25%) Pferden wurden bei der Erstuntersuchung um ein Vielfaches höhere Werte gemessen als bei den übrigen Patienten und Versuchstieren. Unerwünschte Nebenwirkungen oder Unverträglichkeitsreaktionen konnten weder bei gesunden noch bei kranken Pferden beobachtet werden. Aufgrund der guten Verträglichkeit sowie der anhaltenden Volumenwirksamkeit ist die Infusion von Infukoll HES bei Pferden mit akuter Kolitis und Kolik zu empfehlen. Es wäre wünschenswert, Infukoll HES bei jedem chirurgischen Kolikpatienten mit beginnender oder manifester Dehydratation einzusetzen und damit Mikrozirkulationsstörungen, v.a. im Bereich des Gastrointestinaltraktes, frühzeitig zu beheben. In vergangenen Studien konnte bereits nachgewiesen werden, dass chirurgische Kolikpatienten eine signifikant höhere Überlebensrate haben, wenn diese mit HES behandelt werden. Ob durch den Einsatz von HES die Inzidenz postoperativer Komplikationen, unter besonderer Berücksichtigung des paralytischen Ileus, gesenkt und dadurch die Rekonvales-zenz verkürzt werden kann, müssen nachfolgende Studien zeigen. / The purpose of this study was to investigate the pharmacokinetic of Infukoll HES 10% and the clinical effects of this solution in various dosages compared to isotonic and hypertonic saline in adult healthy horses. In a follow up prospective investigation the clinical effectiveness of the plasma volume substitute in horses with colic or acute colitis was proven. The trial group consisted of 6 normal warmblooded mares which received 5 series of a single dose i.v. infusion of HES each, at a does of 5 ml/kg bwt (series no. 1), 10 ml/kg bwt (series no. 2) and 15 ml/kg bwt (series no. 3) as well as isotonic saline (15 ml/kg bwt &#150; series no. 4) and hypertonic saline (4 ml/kg bwt &#150; series no. 5). Patients were classified into 3 groups: horses with acute colitis (group 1; n=8), horses with ileus of the small intestine (group 2; n=7) and with ileus of the large intestine (group 3; n=9). All 3 groups received an i.v. bolus infu-sion of isotonic saline (10 ml/kg bwt) and Infukoll HES (10 ml/kg bwt). Subsequently the fluid therapy was continued with isotonic saline at a dose of 4 ml/kg/h. Blood samples were collected immediately pre and post application after 10 minutes, 1, 2, 4, 6, 8, 10, 12 and 24 hours. At each time a complete blood count as well as total plasma protein and albumin concentration were determined. Amylase activity, glucose, urea and creatinine concentration in serum samples were measured in greater intervals. Only in the trial groups HES was determined in serum samples during a period of 24 hours and urinary values (urine density, GGT-creatinine-ratio, fractional excretion of Na, K, P) were measured or calculated within 4 hours after bolus infusion. In the trial group the infusion of Infukoll HES at each dosage was significantly more effec-tive as isotonic and hypertonic saline &#150; measured on the dilution parameters PCV, hemoglobin, total plasma protein and albumin concentration. A clinical relevant influence of renal function was not proven in healthy horses. The application of Infukollâ HES resulted in a dose dependent prolongation of the APTT caused by hemodilution. However used the influence of the various dosages might not be relevant. Overall HES behave in horses as equal as in human beings. It shows a linear pharmacokinetic and an almost intravascular distribution. The administration of HES causes a significant and dose dependent increase in amylase activity. In horses this form has never been published before. In patients the application of Infukoll HES causes a significant improvement of hydration status and cardiac function. The influence of renal function and the APTT is slight when compared with the effects of shock and the trauma of surgery. A temporary, not significant increase of urea as well as a prolongation of the APTT was observed after the bolus infusion with HES. Already pre infusion values of both of these parameters were pathologically high in the majority of the patients. There is a highly significant correlation between survival and APTT as well as heart rate at pre infusion values (p<0,01). Amylase activity behave in patients as equal as in trial horses and increased significantly. In 6/24 (25%) horses pre infusion values were considerably higher than in the other patients and in the trial horses. No incompatibility reactions or side effects were observed neither in trial horses nor in patients. Because of the well tolerability and the long lasting volume effect Infukoll HES can be recommended for use in horses with colic or acute colitis. It would be desirable to use Infukoll HES in each case of colic surgery and dehydration because it is necessary in these patients to rapidly correct disturbances of microcirculation especially of the gastrointestinal tract. A significantly higher survival rate of HES treated horses undergoing colic surgery has been already proven in former investigations. Clinical studies in progress may confirm if the incidence of post operative complications particularly of the paralytic ileus might be lower and the recovery from surgery might be shorter.

Sensory neurons are key mediators of the transduction of external stimuli from the ear to the brain, essential for the sense of balance and hearing. Understanding when, where and how the sensory nervous system is assembled during development can provide insights on deafness and balance disorders. Here, I show in zebrafish that Her9 transcription factor is a key element in the regulation of the otic neurogenesis. Loss of Her9 function leads to the ectopic expression of neurogenic genes neurod and neurod4. Moreover, I show that Her9 acts downstream of Tbx1, and both genes are activated by retinoic acid signaling emanating from the paraxial mesoderm and negatively regulated by Hedgehog signaling. Altogether, the data demonstrates a role of retinoic acid in axial patterning and the establishment of a neurogenic domain through Tbx1 and Her9. At later stages, retinoic acid has an additional role by regulating neuronal differentiation in the statoacoustic ganglion. / Les neurones sensorials de l’oïda interna són mediadores claus en la transducció dels estímuls externs des de l’oïda interna al cervell. Entendre a on, quan i com el sistema nerviós sensorial s’organitza durant el desenvolupament embrionari pot ajudar en l’estudi de les malalties neurosensorials. En el present treball, mostro en peix zebra que el factor de transcripció Her9 és un element clau en el control de la neurogènesi òtica i que Her9 es troba sota el control directe del factor Tbx1. A més, ambdos factors estan regulats de manera positva per la via de senyalització de l’àcid retinoic i negativament per la vía de hedgehog. En resum, la tesis demostra un paper de l’àcid retinoic en la regionalització axial del primordi òtic en l’eix anteroposterior i l’establiment d’un domini neurogènic a través de Tbx1 i Her9. En estadis tardans, l’àcid retinoic regula la diferenciació neuronal en el gangli estato-acústic.

In einer kontrollierten Studie an gesunden Pferden wurde die Pharmakokinetik von Infukoll HES 10% untersucht und dessen klinische Wirksamkeit in unterschiedlichen Dosierungen mit der von isotoner und hypertoner NaCl-Lösung verglichen. In einer darauffolgenden prospektiven klinischen Untersuchung an Pferden mit akuter Kolitis oder Ileus konnte die Wirksamkeit des Plasmaexpanders am Pferdepatienten dokumentiert werden. Die Versuchsgruppe, bestehend aus 6 Warmblut-Stuten, nahm an 5 Versuchsreihen teil und erhielt jeweils als einmalige i.v. Bolusinfusion Infukoll HES in der Dosierung von 5 ml/kg KM (Reihe 1), 10 ml/kg KM (Reihe 2) und 15 ml/kg KM (Reihe 3) sowie isotone NaCl-Lösung (15 ml/kg KM &#150; Reihe 4) und hypertone NaCl-Lösung (7,5%ig; 4 ml/kg KM &#150; Reihe 5). Die Patienten wurden in 3 Gruppen unterteilt: Pferde mit akuter Kolitis (Gruppe 1; n=8), Pferde mit Dünndarmileus (Gruppe 2; n=7) und Pferde mit Dickdarmileus (Gruppe 3; n=9). Alle Patientengruppen erhielten zunächst eine i.v. Bolusinfusion, bestehend aus 10 ml isotoner NaCl-Lösung/kg KM und 10 ml Infukoll HES/kg KM. Anschließend wurde die Infusionstherapie mit isotoner NaCl-Lösung (4 ml/kg/h DTI) fortgeführt. Blutentnahmen erfolgten bei gesunden und kranken Pferden vor der Bolusinfusion sowie 10 Minuten, 1, 2, 4, 6, 8, 10, 12 und 24 Stunden danach. Zu allen Messzeitpunkten wurde ein Blutbild angefertigt und die Konzentration von GEW und Albumin im Serum ermittelt. In größeren Abständen erfolgte die Bestimmung der Amylaseaktivität und der Konzentrationen von Glukose, Harnstoff sowie Kreatinin. Ausschließlich bei der Versuchsgruppe wurde zusätzlich die HES-Konzentration im Serum über 24 Stunden sowie Harnparameter (Dichte, GGT-Kreatinin-Verhältnis, Fraktionelle Exkretion von Na, K, und P) innerhalb der ersten 4 Stunden nach der Bolusinfusion bestimmt. In der Versuchsgruppe war die Infusion mit Infukoll HES, gemessen an den Dilutionsparametern Hämatokrit, Hämoglobin, GEW und Albumin, in jeder der verwendeten Dosierung signifikant volumenwirksamer als isotone und hypertone NaCl-Lösung. Es konnte keine klinisch relevante Beeinflussung der Nierenfunktion beim nierengesunden Pferd nachgewiesen werden. Die Infusion von Infukoll HES führt zu einer dosisabhängigen und dilutionsbedingten Verlänge-rung der APTT; die Beeinflussung durch die verwendeten Dosierungen darf als klinisch irrelevant bezeichnet werden. HES verhält sich beim Pferd im wesentlichen wie beim Menschen. Sie zeigt eine lineare Pharmakokinetik und verteilt sich fast ausschließlich intravasal. Es konnte erstmals nachgewiesen werden, dass auch beim Pferd ein signifikanter und dosisabhängiger Anstieg der Serumamylaseaktivität nach der Infusion mit HES erfolgt. In den Patientengruppen führte die Bolusinfusion mit Infukoll HES zu einer signifikanten Verbesserung des Hydratationszustandes und der Herz-Kreislauf-Funktion. Die Nierenfunktion wurde nachhaltig verbessert, trotz einer vorübergehenden, nicht signifikanten Erhöhung der Harnstoff-Konzentration im Serum. Eine Verlängerung der APTT wurde eine Stunde nach der Infusion mit HES beobachtet. Beide Parameter waren bei der Mehrzahl aller Patienten bereits zum Zeitpunkt der Erstuntersuchung pathologisch erhöht. Bereits zu diesem Zeitpunkt korrelierten APTT und Herzfrequenz hochsignifikant mit dem späteren Überleben der Patienten (p<0,01). Die Amylase verhielt sich wie bei den Versuchstieren und stieg signifikant an. Bei 6/24 (25%) Pferden wurden bei der Erstuntersuchung um ein Vielfaches höhere Werte gemessen als bei den übrigen Patienten und Versuchstieren. Unerwünschte Nebenwirkungen oder Unverträglichkeitsreaktionen konnten weder bei gesunden noch bei kranken Pferden beobachtet werden. Aufgrund der guten Verträglichkeit sowie der anhaltenden Volumenwirksamkeit ist die Infusion von Infukoll HES bei Pferden mit akuter Kolitis und Kolik zu empfehlen. Es wäre wünschenswert, Infukoll HES bei jedem chirurgischen Kolikpatienten mit beginnender oder manifester Dehydratation einzusetzen und damit Mikrozirkulationsstörungen, v.a. im Bereich des Gastrointestinaltraktes, frühzeitig zu beheben. In vergangenen Studien konnte bereits nachgewiesen werden, dass chirurgische Kolikpatienten eine signifikant höhere Überlebensrate haben, wenn diese mit HES behandelt werden. Ob durch den Einsatz von HES die Inzidenz postoperativer Komplikationen, unter besonderer Berücksichtigung des paralytischen Ileus, gesenkt und dadurch die Rekonvales-zenz verkürzt werden kann, müssen nachfolgende Studien zeigen. / The purpose of this study was to investigate the pharmacokinetic of Infukoll HES 10% and the clinical effects of this solution in various dosages compared to isotonic and hypertonic saline in adult healthy horses. In a follow up prospective investigation the clinical effectiveness of the plasma volume substitute in horses with colic or acute colitis was proven. The trial group consisted of 6 normal warmblooded mares which received 5 series of a single dose i.v. infusion of HES each, at a does of 5 ml/kg bwt (series no. 1), 10 ml/kg bwt (series no. 2) and 15 ml/kg bwt (series no. 3) as well as isotonic saline (15 ml/kg bwt &#150; series no. 4) and hypertonic saline (4 ml/kg bwt &#150; series no. 5). Patients were classified into 3 groups: horses with acute colitis (group 1; n=8), horses with ileus of the small intestine (group 2; n=7) and with ileus of the large intestine (group 3; n=9). All 3 groups received an i.v. bolus infu-sion of isotonic saline (10 ml/kg bwt) and Infukoll HES (10 ml/kg bwt). Subsequently the fluid therapy was continued with isotonic saline at a dose of 4 ml/kg/h. Blood samples were collected immediately pre and post application after 10 minutes, 1, 2, 4, 6, 8, 10, 12 and 24 hours. At each time a complete blood count as well as total plasma protein and albumin concentration were determined. Amylase activity, glucose, urea and creatinine concentration in serum samples were measured in greater intervals. Only in the trial groups HES was determined in serum samples during a period of 24 hours and urinary values (urine density, GGT-creatinine-ratio, fractional excretion of Na, K, P) were measured or calculated within 4 hours after bolus infusion. In the trial group the infusion of Infukoll HES at each dosage was significantly more effec-tive as isotonic and hypertonic saline &#150; measured on the dilution parameters PCV, hemoglobin, total plasma protein and albumin concentration. A clinical relevant influence of renal function was not proven in healthy horses. The application of Infukollâ HES resulted in a dose dependent prolongation of the APTT caused by hemodilution. However used the influence of the various dosages might not be relevant. Overall HES behave in horses as equal as in human beings. It shows a linear pharmacokinetic and an almost intravascular distribution. The administration of HES causes a significant and dose dependent increase in amylase activity. In horses this form has never been published before. In patients the application of Infukoll HES causes a significant improvement of hydration status and cardiac function. The influence of renal function and the APTT is slight when compared with the effects of shock and the trauma of surgery. A temporary, not significant increase of urea as well as a prolongation of the APTT was observed after the bolus infusion with HES. Already pre infusion values of both of these parameters were pathologically high in the majority of the patients. There is a highly significant correlation between survival and APTT as well as heart rate at pre infusion values (p<0,01). Amylase activity behave in patients as equal as in trial horses and increased significantly. In 6/24 (25%) horses pre infusion values were considerably higher than in the other patients and in the trial horses. No incompatibility reactions or side effects were observed neither in trial horses nor in patients. Because of the well tolerability and the long lasting volume effect Infukoll HES can be recommended for use in horses with colic or acute colitis. It would be desirable to use Infukoll HES in each case of colic surgery and dehydration because it is necessary in these patients to rapidly correct disturbances of microcirculation especially of the gastrointestinal tract. A significantly higher survival rate of HES treated horses undergoing colic surgery has been already proven in former investigations. Clinical studies in progress may confirm if the incidence of post operative complications particularly of the paralytic ileus might be lower and the recovery from surgery might be shorter.

Philosophiae Doctor - PhD / This research project explored the learning experiences of two groups of first-year students in the Faculty of Economic and Management Sciences, University of the Western Cape during the course of 2009/2010. The aim was to obtain insight into the learning challenges that these students encountered and the reasons why some of them were less successful in the learning process, while others were successful. The perspective of this study was therefore student centred. The project was undertaken against the backdrop of a higher education institution that caters mainly for so-called 'disadvantaged' and 'underprepared' students. Such students come predominantly from marginalised and poorly resourced education environments and socio-economic backgrounds, which suggests that they would find higher learning challenging and, as a result, would most likely experience failure in the learning process. The objective of the research project was two-fold: firstly, to identify and determine which factors have an impact on failure or successful completion of the first year of study in this faculty; and secondly, to derive from the data a socially situated, supportive and holistic learning approach that could assist more students to be successful in the learning process. The argument in the study was that learning is socially situated and constructed. To realise the objective, Vygotsky's social cultural theory and Bandura's social cognitive theory were used as theoretical orientation of the study. This qualitative, interpretive inquiry was characterised by multiple data collection methods. Qualitative data concerning the perceptions of the participants were generated via written reflective pieces, a questionnaire and individual interviews and content analysis. In addition, quantitative data were collected and this further contributed to the triangulation of rich, in-depth data. An 'open coding' strategy for the content analysis was used, but the approach for the analysis was not purely inductive. A student-centred analytical framework based in part on theories and findings of five studies conducted on student learning, failures and dropouts, and the context of UWC as HSU served as a framework for the analysis but new subthemes also emerged from the data collected The results of these two Case studies revealed that some of the students experienced multiple learning challenges simultaneously which increased in severity during the course of the academic year, and that, in Case 1, these challenges became too overwhelming and severe for the students and that was why they were less successful; while in Case 2, the students managed to overcome and deal with these challenges successfully. The findings of this project, while specific to the context in which it was undertaken, contribute to the growing body of knowledge in the field of higher education and in the identification of enabling factors that could assist more students to be successful in their first year of study at a higher education institution. The findings provide guidelines for a socially situated, supportive and holistic learning approach that could help higher education institutions to mitigate the cumulative effects of learning on students' personal, academic and social lives.

The thesis comprises the synthesis and spectroscopic characterization of novel lipid derivatives mainly of the cancerostatic 5-fluorouridine (5-FU). The chemical structure of the lipid residues resembles naturally occurring compounds, namely acyclic terpenes, waxes, and large ring ketones. They are positioned either at N(3) or at the O-2’,3’ cis-glycolic moiety of the nucleoside. The introduction of the lipophilic residues was performed either by ketalization of the glyconic hydroxyls or by direct alkylation as well as by Mitsunobu reaction at N(3) of the aglycone. The resulting nucleolipids were further converted to 2-(cyanoethyl) phosphoramidites as building blocks for automated solid phase nucleic acid synthesis. The latters were used for the preparation of a series of lipo-oligonucleotides which were studied with respect to their immobilization within artificial lipid bilayers and compared concerning immobilization rate and stability. Moreover, selected 5-FU nucleolipids were fluorophore-labelled and tested with respect to their cancerostatic activity towards human colon carcinoma cells (HT-29). Additionally, O-2’,3’-functionalized 5-FU ketals were covalently bound either to soluble chitosanes of various molecular weight or to chitosane foils. The latters were studied towards their enzymatic degradability. Last, the reaction of lipophilic phosphoramidites with the blood volume expander hydroxyethyl starch yielding enzymatically hydrolysable phosphodiester bonds was investigated.

No description available.

High-performance variable-speed drives, such as PMSM and BLDC, rely on instantaneous torque control. Over the years, several strategies have been investigated in this domain, with the prominent strategies being field-oriented control and direct torque control. Regardless of the strategy employed, a precise rotor position during operation is an essential requirement. While a wide range of sensing technologies to monitor the rotor position have been employed, industries at large presently focus on Hall effect sensors for this application because they are highly cost-effective, low maintenance, noninvasive, and occupy very little space compared to its alternatives. However, the downside of using Hall effect sensors is their low accuracy. In particular, in the application of handheld battery-powered tools, output signals are affected by vibrations and harmonics from the electromagnetic field. Approaches that are being investigated to reduce or eliminate this noise from the signals can be broadly categorized into 1) installation position optimization, 2) filter methods, and 3) measurement model methods. As they are widely cited and easy to implement in the application of handheld battery-powered tools, four filter structures, namely, ANF with PLL, only PLL, SFE, and SFE with PLL, have been investigated in this thesis. This thesis evaluated the filter’s performance when applied to a real-world application of battery-powered tools. The filters were evaluated for their ability to preserve fundamental frequency components and reject harmonic content up to the 5th order. Visual inspections of Lissajous curves, rotor angle curves and generated reference signals provided insights into peculiarities during operation. Operations were categorized into four scenarios to facilitate the examination of filter response during acceleration and steady state in forward and reverse directions. Only performances of ANFPLL and SFE-PLL proved to be satisfactory with some limitations. The SFE filter yielded insignificant results which could be attributed to a lack of feedback mechanism. While the findings presented in this thesis contribute to the understanding of the viability of filter applications in batterypowered tools, additional testing is imperative. This entails the conversion of filter structures into algorithms suitable  for integration within software frameworks, ensuring their practical applicability and efficacy in real-world scenarios. / Högpresterande frekvensomriktare, såsom Permanent Magnet Synchronous Motor (PMSM) och Brushless DC Electric Motor (BLDC), förlitar sig på momentan vridmomentkontroll. Under årens lopp har flera strategier undersökts inom detta område, där de framträdande strategierna är fältorienterad kontroll och direkt vridmomentkontroll. Oavsett vilken strategi som används är en exakt rotorposition under drift ett väsentligt krav. Medan ett brett utbud av avkänningstekniker för att övervaka rotorns position har använts, fokuserar industrier i stort på Hall-effektsensorer för denna applikation eftersom de är mycket kostnadseffektiva, låga underhållskostnader, ickeinvasiva och upptar mycket lite utrymme jämfört med dess alternativ. Men nackdelen med att använda Hall-effektsensorer är deras låga noggrannhet. I synnerhet vid tillämpning av handhållna batteridrivna verktyg påverkas utsignalerna av vibrationer och övertoner från det elektromagnetiska fältet. Tillvägagångssätt som undersöks för att minska eller eliminera detta brus från signalerna kan brett kategoriseras i 1) installationspositionsoptimering, 2) filtermetoder och 3) mätmodellmetoder. Eftersom de är allmänt citerade och lätta att implementera i tillämpningen av handhållna batteridrivna verktyg, fyra filterstrukturer, nämligen Adaptive Notch Filter (ANF) med Phase Locked Loop (PLL), endast PLL, Synchronous Frequency Extractor (SFE) och SFE med PLL, har undersökts i denna avhandling. Denna avhandling utvärderade filtrets prestanda när det tillämpades på en verklig tillämpning av batteridrivna verktyg. Filtren utvärderades med avseende på förmågan att bevara grundfrekvenskomponenten och avvisa övertonsinnehåll upp till 5:e ordningen. Visuella inspektioner av Lissajous-kurvor, rotorvinkelkurvor och genererade referenssignaler gav insikter om egenheter under drift. Operationer kategoriserades i fyra scenarier för att underlätta undersökning av filterrespons under acceleration och stationärt tillstånd i framåt- och bakåtriktning. Endast prestanda av ANF-PLL och SFE-PLL visade sig vara tillfredsställande med vissa begränsningar. SFE-filtret gav obetydliga resultat som kunde tillskrivas bristen på återkopplingsmekanism. Även om resultaten som presenteras i denna avhandling bidrar till förståelsen av användbarheten av filtertillämpningar  i batteridrivna verktyg, är ytterligare tester absolut nödvändiga. Detta innebär omvandling av filterstrukturer till algoritmer lämpliga för integration inom mjukvaruramverk, vilket säkerställer deras praktiska tillämpbarhet och effektivitet i verkliga scenarier.

The study investigated whether a relationship existed between using technology for recreation, and attachment style with important individuals in the lives of respondents. The main results showed that (4) a decrease in friend anxiety contributes towards an increase in the positive attitude towards using the HES for explicit content; (5) An increase in romantic partner anxiety contributed towards an increase in the positive attitude towards using the HES for social replacement. (6) Decreased father avoidance and increased father anxiety lead to an increasingly positive attitude towards using the PC for social, romantic and sexual improvement; (7) an increase in mother avoidance and anxiety, partner anxiety and friend anxiety contributed towards an increase in the positive attitude towards using the cell phone for explicit content and relationship related activities. / Psychology / (M.A. (Psychology))