Mobilität in der kooperativen Wissensarbeit : Entwicklung einer Musterarchitektur für mobil-verteilte Wissensräume

Bernd EßmannPaderborn, Univ., Diss., 200

Flexwork in the context of Burnout-Research

In dieser Arbeit wird das Thema Flexwork im Kontext der Burnout-Forschung vorgestellt. Der Fokus liegt hierbei auf potentiell negativen Folgen des Flexwork. Ziel dieser Ausarbeitung ist es, das Konstrukt des Flexwork konkreter zu fassen und zu untersuchen, ob das Burnout-Syndrom eine spezifische Folge von Flexwork sein kann. Zunächst werden einschlägige theoretische Grundlagen erläutert. Nach einer Einführung in die methodische Vorgehensweise qualitativer und quantitativer Forschungsinstrumente werden die Interviewergebnisse dargestellt. Anschließend wird der Entwurf für einen Fragebogen vorgestellt, der das Ziel hat, zu erfassen, ob und inwiefern Flexwork einen Auslöser für das Burnout-Syndrom darstellt. Im Diskussionsteil dieser Projektarbeit erfolgen eine kritische Betrachtung der methodischen Vorgehensweise sowie eine zusammenfassende Bewertung der Thematik.This research report approaches the subject of Flexwork in the context of Burn-out-Research. The focus lies on the underlying negative effects of Flexwork. The key objective of this paper is to specify the construct of Flexwork and to analyze whether the Burnout-Syndrome can be a specific consequence of Flexwork. Initially, theoretical fundamentals are elucidated. After an introduction into the methodological procedure of qualitative and quantitative instruments of research, the interview-results are illustrated. Subsequently, a blue-print of a questionnaire with the goal of measuring whether or not Flexwork can be seen as an actuator of the Burnout-Syndrome is presented. In the discussion, a critical consideration of the methodological procedures and an overall conclusion is given

Mechanisms of Apoptosis in Cancer: Regulatory Role of Caspases

This thesis will cover two main areas:The identification of the initiating signalling pathway of drug-induced apoptosis in the human B-cell lymphoma cell line BJAB, and insights into apoptosis related events induced by cytostatic drug-treatment. The one area governs questions regarding specific events and/or proteins associated with apoptosis:To elucidate the initiating pathway of drug-induced apoptosis the cascade of apoptotic events was unravelled starting at the most downstream event of apoptosis:drug-induced cell death. It was shown that during apoptosis DNA is degraded and one of the most downstream substrates of caspases, PARP (poly-ADP ribose polymerase), was specifically cleaved during drug-induced apoptosis in BJAB cells. Moreover, caspase-3, caspase-9 and caspase-8 activation was detected by western blot analysis. Processing of caspase-8 rose the question for the initiating point of the caspase cascade during drug-induced apoptosis because caspase-8 is reported to be the most upstream-located initiator caspase in CD95/Fas-induced apoptosis. Disruption of mitochondrial membrane potential, an event that is located upstream of caspase-9 activation, was examined by flow cytometric analysis and BJAB/mock cells were shown to undergo significant loss of mitochondrial membrane potential. To further investigate the role of caspase-8 processing stably transfected cells, harbouring a dominant-negative mutant of the adaptor molecule FADD were used. Overexpression of the dominant negative mutant of FADD (FADDdn) abrogates transmission of the CD95/Fas death signal into the cytoplasm and blocks apoptosis. Western blot analysis showed that transfection with FADDdn had no significant influence on caspase-8 processing in cytostatic drug-induced apoptosis. CD95/Fas-independent processing of caspase-8 was confirmed using a cell free extract system. Western blot analysis and caspase substrate assays from in vivo and in vitro experiments locate caspase-8 processing downstream of caspase-3 in different human B cell lymphoma cell lines: BJAB/mock, BJAB/FADDdn, NALM6 and REH. The second area governs a more general setup:2DE-PAGE analysis of samples derived from drug-treated cells and control samples was performed and evaluated by subtractive analysis. These experiments lead to the identification of several caspase substrates, including D4-GDI (rho GDP dissociation inhibitor 2). Using the caspase-3 specific inhibitor Z- DEVD-fmk it was shown that D4-GDI is being cleaved by active caspase-3 in cultured apoptotic BJAB cells. This result was confirmed in cell free extracts and by immunochemical depletion of procaspase-3. As caspase-1 is also reported to proteolyze D4-GDI, further experiments were performed. Western blot analysis showed no increase in concentration of the mature subunit p20 of caspase-1 and in a caspase activity assay no significant activity of caspase-1 could be detected. Finally, mass spectrometric analysis of the resulting D4-GDI fragment clearly showed that caspase-3 and not caspase-1 is responsible for cleavage of D4-GDI after drug treatment of BJAB cells. Moreover, it is demonstrated that apoptotic cell death bears no consequences for Rho-GDI 1, a protein which displays high homology to D4-GDI. However, the results indicated that the applied methodology is not sufficient to detect changes of regulatory factors on protein level after drug-treatment of BJAB/mock cells. Therefore, analytical efforts were made to overcome this problem and Annexin V-coupled magnetic beads were used to separate apoptotic from non-apoptotic cells. However, this method did not lead to the identification of regulatory proteins during apoptotic cell death. In another attempt, the visualisation technique was sensitized by metabolic radioactive labeling of proteins. By this method, detection limits are lowered and changes in a specific time frame can be monitored. Results obtained so far indicate that this method is suitable for detection of regulatory proteins but inherits other difficulties:in most cases the amount of regulatory proteins is far below the limit of mass spectrometric analysis and identification. For example, one spot displaying considerable variation in intensity was detected on images of 2DE PAGE gels derived from metabolic labeled samples but its identification was not yet successful

Biliäre Komplikationen nach Lebertransplantation - Erfahrungen am UKT bei 160 adult DDLT

Da biliäre Komplikationen nach wie vor als die Achillesferse der Lebertransplantation bezeichnet werden können, kommt ihrer Vermeidung und Therapie eine eminente Rolle zu. Das Ziel dieser retrospektiven Studie war es, den Einfluss von verschiedenen Faktoren auf die Entwicklung von Gallengangskomplikationen nach erstmaliger Lebertransplantation bei postmortaler Organspende bei volljährigen Patienten zu untersuchen. Für die wissenschaftliche Untersuchung von Themen rund um das Thema Lebertransplantation wurde hierzu eine Datenbank aufgebaut und somit für weitere Studien die Grundlage geschaffen. Hierfür wurden 160 Patienten untersucht, die in dem Zeitraum vom 01.01.2009 bis zum 31.12.2013 am Universitätsklinikum Tübingen lebertransplantiert wurden. Die biliären Komplikationen wurden aufgeteilt in: biliäre Leckagen, biliäre Strikturen (anastomotische und nicht anastomotische Strikturen), biliäre Konkremente und Cholangitis. Biliäre Komplikationen stellten in unserer Studie die Hauptursache eines Transplantatverlusts dar. Zur Identifikation verschiedener Einflussfaktoren auf die Entstehung von biliären Komplikationen führten wir zunächst eine Univariatanalyse durch. Statistisch signifikante Einflussfaktoren wurden genauer betrachtet und mittels Multivariatanalyse verifiziert. Hierzu wurden, um Konfusoren auszuschließen nur Patienten mit Duct-to-Duct-Anastomose in die Analyse einbezogen. Biliären Leckagen traten in unserem Patientenkollektiv nicht hinreichend häufig auf, um die Ergebnisse ausreichend zu interpretieren. Aus dieser Studie konnten folgende Erkenntnisse gewonnen werden: • Anastomotische Strikturen sind vor allem von dem Zustand des Patienten vor LT abhängig (Lab MELD bei LT) sowie von einer chronischen Abstoßungsreaktion nach LT. • Nicht anastomotische Strikturen sind von dem Spenderorgan abhängig. Zur Vermeidung sollte besonderes Augenmerkt auf das Spenderalter gelegt werden. Organangebote von Spendern >70 Jahre, und mit hohem DRI sollten sorgfältig geprüft werden. Der DRI war in unserer Studie dem Spenderalter bei der Vorhersage von NAS unterlegen. Der ET-DRI war nicht zur Vorhersage von NAS geeignet. • Chirurgische Faktoren wie Nahtmaterial und Nahttechnik sowie Zeitpunkt der OP (Tag/Nacht) hatten keinen Einfluss auf die Entwicklung von BK. • Die Zeit zwischen Start der kalten Perfusion des Spenderorgans und der Hepatektomie hatte keinen Einfluss auf die Entwicklung von BK

Verified Approximation Algorithms

We present the first formal verification of approximation algorithms for NP-complete optimization problems: vertex cover, independent set, set cover, center selection, load balancing, and bin packing. We uncover incompletenesses in existing proofs and improve the approximation ratio in one case. All proofs are uniformly invariant based

Brain Responses During Robot-Error Observation

Brain-controlled robots are a promising new type of assistive device for severely impaired persons. Little is however known about how to optimize the interaction of humans and brain-controlled robots. Information about the human's perceived correctness of robot performance might provide a useful teaching signal for adaptive control algorithms and thus help enhancing robot control. Here, we studied whether watching robots perform erroneous vs. correct action elicits differential brain responses that can be decoded from single trials of electroencephalographic (EEG) recordings, and whether brain activity during human-robot interaction is modulated by the robot's visual similarity to a human. To address these topics, we designed two experiments. In experiment I, participants watched a robot arm pour liquid into a cup. The robot performed the action either erroneously or correctly, i.e. it either spilled some liquid or not. In experiment II, participants observed two different types of robots, humanoid and non-humanoid, grabbing a ball. The robots either managed to grab the ball or not. We recorded high-resolution EEG during the observation tasks in both experiments to train a Filter Bank Common Spatial Pattern (FBCSP) pipeline on the multivariate EEG signal and decode for the correctness of the observed action, and for the type of the observed robot. Our findings show that it was possible to decode both correctness and robot type for the majority of participants significantly, although often just slightly, above chance level. Our findings suggest that non-invasive recordings of brain responses elicited when observing robots indeed contain decodable information about the correctness of the robot's action and the type of observed robot

A Smart Ground Support Equipment: Design and Demonstration of a Robotic GSE for Small Spacecraft Integration and Verification

In order to reduce the costs of integration and verification processes and to optimize the assembly, integration and verification (AIV) flow in the prototype development of small- and medium-sized spacecrafts, an industrial six-axis robot was used as a universal mechanical ground support equipment instead of a tailored prototype specific ground support equipment (GSE). In particular, a robotic platform offers the possibility of embedding verification steps such as mass property determination into the integration process while offering a wider range of ergonomic adaption due to the enhanced number of degrees of freedom compared to a classical static Mechanical GSE (MGSE). This reduces development costs for projects and enhances the flexibility and ergonomics of primarily mechanical AIV operations. In this paper, the robotic MGSE system is described, the operational prospects for in-line verification are elaborated and an example is given showing the possibilities and challenges of its operational use as well as its in-line mass determination capabilities. For this purpose, a method has been developed that allows for the precise measurement of the spacecraft mass using the robot’s existing technology without the need for additional hardware. Subsequent work will extend this to determine the center of gravity and the moments of inertia of the payload on the robotic MGSE

Single-Step Screening of the Potential Dependence of Metal Layer Morphologies along Bipolar Electrodes

The preparation of surface gradients is a hot topic in contemporary research. Among various physical chemistry approaches, bipolar electrochemistry allows the control of such gradients through the interfacial polarization between a conducting substrate and an electrolyte solution. Here, we report the straightforward, single‐step generation of metal composition gradients on cylindrical carbon fibers. The screening of different metal deposit morphologies, which evolve gradually along a bipolar electrode, is demonstrated with monometallic layers as well as a bimetallic composite layer based on copper and nickel

Snatching a probe of a genuine Near-Earth Asteroid: Fast sample return opportunity in the frame of RAMSES mission scenario

A mission to (99942) Apophis would provide a unique opportunity to collect and return a regolith sample from a Near-Earth asteroid (NEA) as it passes very close to Earth. ESA is currently investigating the possibility of an orbiter, as part of the RAMSES mission study, to fly close to (99942) Apophis before it makes its closest approach to Earth on Friday 13 April 2029, with the aim of observing the tidal and magnetospheric effects on the NEA during this close flyby. Later, the asteroid will be well observed by the OSIRIS-APEX (or OSIRIS-REx Extended Mission to Asteroid Apophis) mission. At present, none of these missions or mission studies are investigating the possibility of sample return with a very short duration sample return leg, requiring only a tiny additional momentum to return to Earth. We present the results of the concurrent engineering (CE) study on the feasibility of a sample return capsule based on "nowterm technology" available from the space industry and the necessary mandatory mechanical, electrical and software interfaces based on the experience gained from previous small asteroid projects

Snatching a sample of a genuine Near-Earth Asteroid: A very swift sample return opportunity

A mission to (99942) Apophis would provide a unique opportunity to collect and return a regolith sample from a Near-Earth asteroid (NEA) as it passes very close to Earth [1,2]. ESA is currently investigating the possibility of an orbiter, as part of the RAMSES mission study, to fly close to (99942) Apophis before it makes its closest approach to Earth on Friday 13 April 2029, with the aim of observing the tidal and magnetospheric effects on the NEA during this close flyby [3]. Later, the asteroid will be well observed by the OSIRIS-APEX (or OSIRIS-REx Extended Mission to Asteroid Apophis) mission. At present, none of these missions or mission studies are investigating the possibility of sample return with a very short duration sample return leg, requiring only a tiny additional momentum to return to Earth. We present the results of the concurrent engineering (CE) study on the feasibility of a sample return capsule based on "now-term technology" available from the space industry and the necessary mechanical, electrical and software interfaces based on the experience gained from previous small asteroid projects