"Major Subject: Information and Operation Management" Title from author supplied metadata (automated record created 2010-03-12 12:08:51). Includes bibliographical references.

Erlangen, Nürnberg, Univ., Diss., 2005.

München, Techn. Univ., Diss., 2004.

Universiẗat, Diss., 2002--Marburg.

Universiẗat, Diss., 2006--Giessen.

No description available.

Determination of the spatial distribution and quantification of concentration of pure beta- and photon-emitting radionuclides in absorbing media by external measurements is the subject of this study. Measurements of radiation and the operation of radiation detectors are based on the radiation interactions with matter and the theory governing these interactions has been discussed. Various techniques for localising pure beta- and photon-emitting radionuclides situated inside attenuating media have been suggested on a theoretical basis, and have been experimentally shown to work successfully. Most of the work is on single photon emission computed tomography (SPECT). The theory of mathematical reconstruction of a two dimensional distribution from its projections is discussed and reconstruction techniques and their relative merits and demerits have been reviewed. SPECT seeks the determination of absolute regional radionuclide concentrations as a function of time. A SPECT system has been developed by modifying an existing transmission CT scanner and the reconstruction algorithms. The performance of the SPECT system has been tested for a number of point sources and various extended sources in gas, liquid and solid forms. The SPECT scanner in its present design is capable of performing in both the transmission and emission modes. The characteristics of the SPECT scanner, including the detector efficiency, spatial resolution and the effect of collimator size, have been studied experimentally. The major problems faced by SPECT include the solid angle effect, which influences the collection efficiency, in scattered radiation, and attenuation of photons inside the surrounding medium. These problems together with their various possible solutions have been discussed in detail. Methods for compensation for solid angle variation, in scattered radiation and photon attenuation have been devised and used successfully to compensate the projection data.

Reliability and safety represent key features of any successful railway system and compromising either has undeniable ramifications. Railway industry practitioners are continually challenged to deliver reliability and performance improvements whilst facing ever increasing service demands. These improvements are typically achieved through track maintenance and renewal activities, which have to be balanced against a requirement to reduce whole life-cycle costs. Research focusing on the optimisation of railway track components, which can then be translated to field practice, presents a real opportunity to reduce the frequency of disruptive and often costly track maintenance activities and ultimately prolong the life span of a railway track. A laboratory study of track performance with particular emphasis on railway sleeper type and geogrid type as the main variables has been undertaken. The types of sleepers investigated were the concrete monoblock, twin-block, timber, plastic, and steel sleepers. The geogrids variants tested were the SSLA30 biaxial and TX130 triaxial geogrids with square and triangular apertures respectively. Testing undertaken involved the application of low frequency cyclic loads to railway sleeper sections and full-size sleepers installed on a 300 mm thick ballast with and without geogrid reinforcement. Bending tests, friction tests and hardness tests were initially performed to characterise the material and mechanical properties of the sleepers investigated. Preliminary cyclic tests were conducted with a Box Test apparatus and Composite Element Test (CET) apparatus to approximate field conditions. Full scale tests were subsequently performed with the Nottingham Railway Test Facility (RTF) which is designed to provide a closer representation of field conditions and simulate the passage of an axle load over three sleepers. The outer sleepers in the test facility provided the necessary boundary conditions for the middle sleeper, which was the primary focus of the tests performed. Measures of track performance included vertical track settlement, trackbed stiffness and formation pressure. Additional measurements were made of the differential deflection along the length of the middle sleeper to ascertain if sleeper bending occurred during the tests. Linear elastic and finite element analysis to determine the pressure on top of the subgrade and at the sleeper-ballast interface respectively were performed for idealised sleeper support conditions. The results of the numerical analysis were compared with the RTF pressure plate measurements and estimates of subgrade pressure calculated using empirically derived equations. The results showed that sleeper type influences the permanent settlement that develops in a railway track as well as the magnitude of transient live loads that is transmitted to an underlying subgrade. In line with the permanent settlement results, it is also apparent that trackbed stiffness is a function of sleeper bending stiffness. Measurements of formation pressure and resilient sleeper deflection revealed differences between sleeper types with regards to their ability to retain the as-built geometry of a trackbed, underlining the importance of the sleeper-ballast interface characteristics and sleeper bending stiffness. Traditionally used empirical equations for determining subgrade pressure were found to be conservative compared to subgrade pressures determined using linear elastic analysis and measurements of made of the same using pressure plates in the RTF. Finite element analysis to determine the pressure distributions at the base of different sleepers for a range of support conditions found the shape and magnitude of pressures determined to be consistent with the sleepers’ bending stiffnesses suggesting that sleeper properties should be an important consideration when predicting track performance. The use of the biaxial geogrid installed 100 mm above the base of the ballast reduced permanent settlement for all sleeper types without any significant bias towards any one sleeper type. Additionally, the use of the biaxial geogrid resulted in the delayed deterioration of sleeper support for all sleeper types. The application of the TX130 geogrid resulted in increased settlement and increased deterioration of the as-built trackbed geometry for all sleeper types owing to the grid aperture which proved unsuited to the standard Network Rail ballast gradation. It was proposed that a triaxial geogrid with a larger aperture may offer better results. It was also suggested that sleeper choice that includes consideration for the relative performance of sleeper types is possible for railway practice although it must be commensurate with the intended use of the track with due regard to cost and safety. The research concluded that the concrete monoblock sleeper, which is currently the prevalent sleeper type in the UK (with and without the biaxial geogrid), for the conditions simulated, presents the best opportunity to minimise the maintenance requirements of a railway track.

Die bariatrische Chirurgie ist momentan die einzige Therapieoption der morbiden Adipositas mit der eine langfristige Gewichtsreduktion erreicht werden kann. Unter den Operationsmethoden gilt der RYGB als eine der wirksamsten Behandlungen bezogen auf den Gewichtsverlust und die Verbesserung von Begleiterkrankungen wie dem Diabetes mellitus Typ 2. Darüber hinaus belegt eine wachsende Zahl an Veröffentlichungen, dass der RYGB den Zustand chronischer Entzündung, wie er typischerweise mit Adipositas einhergeht, verringern kann. Diese sogenannte Endotoxämie geht unter anderem mit einer gestörten Integrität der intestinalen Epithelbarriere einher. Ziel der vorliegenden Arbeit war es eine Analyse der Veränderungen von für die Darmbarriere wichtigen Junktionsproteinen vorzunehmen, um eine Grundlage für künftige mechanistische Untersuchungen zu schaffen. Dafür wurden die Veränderungen von Barriereproteinen in Vollwandresektaten des Duodenums, des Jejunums, des Ileums sowie des Kolons von Ratten, die einen RYGB erhalten hatten, mittels Western Blot Untersuchungen quantifiziert. Als Kontrollgruppe dienten schein-operierte Ratten. Es kam zu tiefgreifenden Veränderungen der analysierten Barriereproteine in den Vollwandresektaten. Interessanterweise unterschieden sich die Verteilungsmuster der Veränderungen der Barriereproteinte deutlich zwischen den einzelnen Darmregionen. Um herauszufinden, ob diese Veränderungen durch regionale Veränderungen der Mikroumgebung nach RYGB- Operation induziert wurden, wurden im reduktionistischen Zellkultursystem Stuhl- Transferexperimente durchgeführt. Caco2-Zellkulturen dienten hierbei als Modell für die intestinale epitheliale Barriere. Es wurden funktionelle Messungen und quantitative Analysen der Veränderungen der Barriereproteine der Zellkultur durchgeführt. Die Funktionsmessungen zeigten, dass der Inhalt des Duodenums, des Jejunums sowie des Kolons deutliche barrierestabilisierende Effekte auf die Caco2-Zellmonolayer hatte. Zudem zeigten sich tiefgreifende Veränderungen der untersuchten Barriereproteine. Zusammenfassend wurde in der vorliegenden Arbeit erstmals eine regionenspezfische Regulation der intestinalen Barriereproteine in Korrelation mit funktionellen Messungen nach RYGB nachgewiesen. / Bariatric surgery is currently the only treatment option for morbid obesity that can achieve long-term weight loss. Among surgical methods, RYGB is considered one of the most effective treatments in terms of weight loss and improvement of associated diseases such as type 2 diabetes mellitus. In addition, a growing number of publications demonstrate that RYGB can reduce the state of chronic inflammation typically associated with obesity. This so-called endotoxemia is associated with impaired integrity of the intestinal epithelial barrier. The aim of the present work was to perform an analysis of changes in junctional proteins which are important for the intestinal barrier in order to provide a basis for future mechanistic studies. For this purpose, the changes of barrier proteins in whole-wall resections of the duodenum, jejunum, ileum, and colon of rats that had received an RYGB were quantified by Western blot studies. Sham-operated rats served as the control group. Profound changes in the analyzed barrier proteins occurred in the whole-wall resectates. Interestingly, the distribution patterns of barrier protein changes differed markedly between intestinal regions. To determine whether these changes were induced by regional changes in the microenvironment after RYGB- surgery, stool transfer experiments were performed in the reductionist cell culture system. Caco2 cell cultures served here as a model for the intestinal epithelial barrier. Functional measurements and quantitative analyses of the changes in the cell culture barrier proteins were performed. The functional measurements showed that the contents of the duodenum, jejunum, as well as the colon had significant barrier-stabilizing effects on the Caco2 cell monolayers. In addition, profound changes in the barrier proteins examined were evident. In summary, the present work was the first to demonstrate region-specific regulation of intestinal barrier proteins in correlation with functional measurements by RYGB.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The requirement for a lightweight, quick deployment C-Band satellite communication antenna system for Aegis Class Destroyers has been addressed and this paper describes a novel solution currently being implemented. The new antenna system takes advantage of the low windload properties of the FLAPS™ (Flat Parabolic Surface) reflector and features a broadband FLAPS™ reflector mounted on a lightweight, high performance X-Y positioner. The system is designed in a modular fashion and operates in a shipboard environment without the protection of a radome. The system is stabilized to counteract the ship's motion, operates without counterweights, weighs less than 250 kg and provide communication links in the 3900 to 4100 MHz and 6000 to 6200 MHz frequency bands.