Deformation constructions of extremal metrics

In the first part of this thesis we investigate the deformation theory of compact constant scalar curvature Kähler (cscK) and extremal Kähler manifolds. In particular, we will characterise deformations of cscK- and extremal Kähler manifolds which again admit a cscK- or extremal Kähler metric, in terms of stability in the sense of geometric invariant theory. In a second part we will investigate a different problem. We will extend the adiabatic methods used by Hong and Fine in the study of cscK-metrics to the study of extremal metrics on ruled manifolds. The analysis in the case of extremal metrics being more involved will bring in some new aspects in carrying out this construction

Bestimmung einer Prognosegüte für TAF-Meldungen

Das Wetter ist der wohl größte Unsicherheitsfaktor, durch den an Verkehrsflughäfen Verspätungen auftreten können. So bedeutet eine geringe Sichtweite höhere Staffelungsabstände gegenüber hohen Sichtweiten, Schnee und Eis sorgen für Verzögerungen durch entsprechende Anti- und De-Icing-Maßnahmen der Flugzeuge, aber auch der Pisten. Um diese Unsicherheiten im Rahmen einer prätaktischen Planung quantifizieren zu können, wurde eine Metrik für die Ermittlung der Prognosegüte einer Wettervorhersage in Form einer TAF (Terminal Aerodrome Forecast) ermittelt, welche im Folgenden vorgestellt wird. Dabei werden die TAF-Meldungen, die für einen Zeitraum von 6 Stunden gelten, mit den tatsächlich eingetroffenen METAR- Meldungen (Meteorological Aerodrome Report) verglichen. Für mehrere Wetterklassen wurden spezifische Modelle zur Bestimmung der Prognosegüte ermittelt und am Beispiel der Sichtweite ausführlich erläutert

Computing Shortest Paths in Series-Parallel Graphs in Logarithmic Space

Series-parallel graphs, which are built by repeatedly applying series or parallel composition operations to paths, play an important role in computer science as they model the flow of information in many types of programs. For directed series-parallel graphs, we study the problem of finding a shortest path between two given vertices. Our main result is that we can find such a path in logarithmic space, which shows that the distance problem for series-parallel graphs is L-complete. Previously, it was known that one can compute some path in logarithmic space; but for other graph types, like undirected graphs or tournament graphs, constructing some path between given vertices is possible in logarithmic space while constructing a shortest path is NL-complete

Benchmarking News Recommendations in a Living Lab

Most user-centric studies of information access systems in literature suffer from unrealistic settings or limited numbers of users who participate in the study. In order to address this issue, the idea of a living lab has been promoted. Living labs allow us to evaluate research hypotheses using a large number of users who satisfy their information need in a real context. In this paper, we introduce a living lab on news recommendation in real time. The living lab has first been organized as News Recommendation Challenge at ACM RecSys’13 and then as campaign-style evaluation lab NEWSREEL at CLEF’14. Within this lab, researchers were asked to provide news article recommendations to millions of users in real time. Different from user studies which have been performed in a laboratory, these users are following their own agenda. Consequently, laboratory bias on their behavior can be neglected. We outline the living lab scenario and the experimental setup of the two benchmarking events. We argue that the living lab can serve as reference point for the implementation of living labs for the evaluation of information access systems

The use of shear stress for targeted drug delivery

Stenosed segments of arteries significantly alter the blood flow known from healthy vessels. In particular, the wall shear stress at critically stenosed arteries is at least an order of magnitude higher than in healthy situations. This alteration represents a change in physical force and might be used as a trigger signal for drug delivery. Mechano-sensitive drug delivery systems that preferentially release their payload under increased shear stress are discussed. Therefore, besides biological or chemical markers, physical triggers are a further principle approach for targeted drug delivery. We hypothesize that such a physical trigger is much more powerful to release drugs for vasodilation, plaque stabilization, or clot lysis at stenosed arteries than any known biological or chemical one

Funktionelle Analyse des Met196Arg-Polymorphismus im humanen TNF-Rezeptor 2

Ein nicht-konservativer Polymorphismus (Methionin 196 -> Arginin) im humanen Rezeptor Typ 2 für das Zytokin TNFalpha ist genetisch assoziiert mit einer Reihe entzündlicher und nicht-entzündlicher degenerativer Erkrankungen. Mit Hilfe von stabiler und transienter Transfektion konnte an zwei in-vitro-Zellmodellen (HeLa-Zellen und immortalisierten Fibroblasten aus TNFR-defizienten Mäusen) gezeigt werden, dass die mutierte Arg-Variante durch verminderte Assoziation mit dem Adaptorprotein TRAF2 den NF-kappaB-Signalweg weniger effektiv aktiviert. Die verringerte Expression antiapoptotischer NF-kappaB-abhängiger Gene (IAPs, TRAFs, MnSOD, Bcl-XL) beeinflusst zudem das apoptotische Verhalten der Zellen unter bestimmten Stimulationsbedingungen. Die Mutation könnte nach den erhobenen Daten in vivo einen direkten Einfluss auf die immunologische Homöostase und den Umgang des Organismus in der Auseinandersetzung mit Pathogenen haben

Overall mental distress and health-related quality of life after solid-organ transplantation: results from a retrospective follow-up study

Background: Our retrospective follow-up study aimed to explore the degree of overall mental distress in a cohort of solid-organ transplantation (SOT) recipients after liver, heart or lung transplantation. Furthermore, we investigated how overall mental distress is linked to health-related quality of life. Methods: 123 SOT patients treated during the study period were enrolled in this investigation at a mean of 24.6 months (SD=11.6) after transplantation. Before transplantation, the Transplant Evaluation Rating Scale (TERS) was used to classify the level of adjustment in psychosocial functioning among transplantation candidates. After transplantation, recipients completed a research battery, which included the SCL-90-R, and the SF-36. Results: 39 (31.7\%) transplantation recipients had clinically significant overall mental distress as measured on the Global Severity Index of the SCL-90-R. Obsessive-compulsive symptoms (92.3\%), somatization symptoms (87.2\%), anxiety symptoms (84.6\%), depression symptoms (82.1\%) and phobic anxiety symptoms (69.2\%) were a frequent finding. Transplantation recipients with overall mental distress had significant lower levels of adjustment in psychosocial functioning before transaplantation than those without overall mental distress as measured in the TERS. Transplantation-related overall mental distress symptomatology was associated with maximal decrements in health-related quality of life. Conclusion: Transplantation recipients may face major transplantation-and treatment-related overall mental distress and impairments to their health-related quality of life. Further, overall mental distress is a high-risk factor in intensifying impairments to patients' overall quality of life

Development of Bifunctional Electrodes for Closed-loop Fuel Cell Applications

Unitized regenerative fuel cells (URFC) in combination with photovoltaic modules are attractive for space missions because they enable extended operation times and low weight. During the planetary day, electrical energy is stored which can be converted into electricity by the fuel cell during the night. All air-independent applications such as spacecraft or space stations would profit signify¬cantly from such energy conversion devices. A unitized regenerative fuel cell is a combined energy con¬version and storage system based on H2 and O2 which combines the advantages of fuel cells and secondary batteries. Substantial advantages of the specific energy density can be expected from the use of a URFC (400-1000 Wh/kg) in comparison to secondary batteries (220-250 Wh/kg for future advanced Li-polymer batteries). An important topic is the function of so-called bifunc¬tional oxygen electrodes which generally require the combination of favourable properties for both operating modes. In particular, different catalysts for oxygen reduction and for oxygen evolution are needed. This contribution investigates various electrode designs with Pt and IrO2 catalysts. For that purpose, the DLR dry spraying technique for the manufacturing of electrodes is applied for by mixing the two different catalysts together (Pt and IrO2) or applying the catalyst on different areas of electrode or even realising different layers with both catalysts. The different options are explained in Fig. 1. Of interest was to compare the simple mixing of the catalysts (option 1), the layered electrode with two compositions (option 2) and the segmented approach with dedicated areas with just one catalyst (option 3)

Posttraumatic stress symptoms after solid-organ transplantation: preoperative risk factors and the impact on health-related quality of life and life satisfaction

Background: Solid-organ transplantations (SOT) are usually life-saving high-tech medical procedures. The transplantation itself and the intensive care unit stay could be traumatic stressors triggering posttraumatic stress symptoms (PTSS). Our retrospective follow-up study aimed to explore preoperative risk factors of PTSS in a cohort of SOT recipients, and we investigated how PTSS are associated with health-related quality of life (HRQOL) and life satisfaction. Methods: 126 SOT recipients were enrolled in this investigation. Psychiatric examination of all SOT candidates based on the Transplant Evaluation Rating Scale was carried out before SOT, and after SOT, recipients completed the PTSS-10, the SF-36 and the FLZ. Results: After the surgical intervention 19 (15.1\%) SOT recipients had clinical significant PTSS. Preoperative risk factors for developing postoperative PTSS were: 1.) preexisting psychiatric morbidity, 2.) history of retransplantation, 3.) chronic benzodiazepine consumption, 4.) age, and 5.) type of transplantation. SOT-related PTSS were associated with maximal decrements in HRQOL and life satisfaction. The following HRQOL and life satisfaction domains were affected: Physical Functioning, Role Physical, Pain, General Health, Vitality, Social Functioning, Role Emotional, Mental Health, Occupation/Work and Character/Own Skills. Conclusion: SOT recipients may face a major risk of transplantation-and treatment-related PTSS and the development of impairments to HRQOL and life satisfaction

Pexophagy: The Selective Degradation of Peroxisomes

Peroxisomes are single-membrane-bounded organelles present in the majority of eukaryotic cells. Despite the existence of great diversity among different species, cell types, and under different environmental conditions, peroxisomes contain enzymes involved in β-oxidation of fatty acids and the generation, as well as detoxification, of hydrogen peroxide. The exigency of all eukaryotic cells to quickly adapt to different environmental factors requires the ability to precisely and efficiently control peroxisome number and functionality. Peroxisome homeostasis is achieved by the counterbalance between organelle biogenesis and degradation. The selective degradation of superfluous or damaged peroxisomes is facilitated by several tightly regulated pathways. The most prominent peroxisome degradation system uses components of the general autophagy core machinery and is therefore referred to as “pexophagy.” In this paper we focus on recent developments in pexophagy and provide an overview of current knowledge and future challenges in the field. We compare different modes of pexophagy and mention shared and distinct features of pexophagy in yeast model systems, mammalian cells, and other organisms