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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

The Human Spiral Ganglion

Tylstedt, Sven January 2003 (has links)
Our knowledge of the fine structure of the Human Spiral Ganglion (HSG) is still inadequate and new treatment techniques for deafness using electric stimulation, call for further information and studies on the neuronal elements of the human cochlea. This thesis presents results of analyses of human cochlear tissue and specimens obtained during neurosurgical transpetrosal removal of life-threatening meningeomas. The use of surgical biopsies produced a well-preserved material suitable for ultrastructural and immunohistochemical studies on the human inner ear. The SG was studied with respect to fine structure, using TEM technique and the immunostaining pattern of synaptophysin, which is an integral membrane protein of neuronal synaptic vesicles. The immunostaining patterns of the tight junctional protein ZO-1 and the gap junctional proteins Cx26 and Cx43 in the human cochlea were also studied. The ultrastructural morphology revealed an absence of myelination pattern in the HSG, thus differing from that in other species. Furthermore, formation of structural units as well as signs of neural interaction between the type 1 neurons could be observed. Type 1 cells were tightly packed in clusters, sharing the ensheathment of Schwann cells. The cells frequently made direct physical contact in Schwann cell gaps in which membrane specializations appeared. These specializations consisted of symmetrically or asymmetrically distributed filamentous densities along the apposed cell membranes. The same structures were also present between individual unmyelinated nerve fibres and the type 1 cells. Synapses were observed on the type 2 neurons, with nerve fibres originating from the intraganglionic spiral bundle. Such synapses, though rare, were also observed on the type 1 cells. The ultrastructural findings were confirmed by the synaptophysin study. A 3-D model of a Schwann cell gap between two type 1 cells was constructed, describing the distribution pattern of membrane specializations. In the immunohistochemical studies on the human cochlea, ZO-1 was expressed in tissues lining scala media, thus contributing to the formation of a closed compartment system, important for the maintenance of the specific ionic composition of the endolymph. Protein Cx26 could be identified in non-sensory epithelial cells of the organ of Corti, in connective tissue cells of the spiral ligament and spiral limbus, as well as in the basal and intermediate cell layers of stria vascularis. Cx26 in this region may be involved in the recycling of potassium. Protein Cx43 stained weakly in the spiral ligament, but intense staining in the SG may indicate that gap junctions exist between these neurons. A different functional role for the HSG can be assumed from the morphological characteristics and the signs of a neural interaction between the SG cells. This might be relevant for neural processing mechanisms in speech coding and could have implications for cochlear implant techniques.
202

Novel in vitro models for pathogen detection based on organic transistors integrated with living cells.

Tria, Scherrine 18 October 2013 (has links) (PDF)
In biological systems, different tissues have evolved to form a barrier. An example is the intestinal epithelium, consisting of a single layer of cells lining the wall of the stomach and colon. It restricts the passage of harmful chemicals or pathogens from the light into the tissue, while selectively absorbing the most nutrients, electrolytes and water are necessary for the host. Tight junctions are structures which limit the passage of the material through the space between the cells. The ability to measure the paracellular and transcellular transport is of vital importance because it provides a wealth of information on the state of the barrier, indicative of certain disease states , since the disruption or malfunction of the structures involved in the transport through the tissue barrier is often caused or is indicative of toxicity or disease. In addition, the degree of integrity of the barrier is a key indicator of the relevance of a particular model in vitro for use in toxicology and drug screening. The advent of organic electronics has created a unique opportunity to connect the worlds of electronics and biology, using devices such as organic electrochemical transistor (OECT), which provides a very sensitive way to detect ionic currents. These devices have unprecedented sensitivity in a format that can be mass produced at low cost.The purpose of this study was to integrate a monolayer of cells representative of the gastro intestinal barrier with OECTs , to create devices that detect disruptions of the barrier in a timely and sensitive manner. This technique was demonstrated to be at least as sensitive, but a higher speed than current techniques on the market
203

Gastight Paperboard Package

Hauptmann, Marek, Schult, Andre, Zelm, Roland, Gailat, Tilo, Lenske, Alexander, Majschak, Jens-Peter, Großmann, Harald 28 October 2013 (has links) (PDF)
Packages made from coated paperboard are currently used in food packaging for frosted or microwave food. These cups are usually deep drawn from flat paperboard blanks. The blanks are pre-creased to control the material overflow that appears during drawing. The resulting wrinkles in the sealing area have to be considered as capillary tubes allowing the gas exchange between the package and the environmental atmosphere. A new technological approach in 3D forming enables the prevention of capillary tubes in the sealing area. The result is a gas-tight sealable paperboard cup which is limited by its coating concerning the degree of gas tightness.
204

Advanced methods for dynamic aeroelastic analysis of rotors

Reveles, Nicolas 22 May 2014 (has links)
Simulations play an integral role in the understanding and development of rotor- craft aeromechanics. Computational Fluid Dynamics coupled with Computational Structural Dynamics (CFD/CSD) offers an excellent approach to analyzing rotors. These methods have been traditionally “loosely-coupled” where data are exchanged periodically, motion is prescribed for CFD, and the updated loads have a static component for CSD. Loosely-coupled CFD/CSD assumes the solution to be periodic, which may not be true for some simulations. “Tightly-coupled” CFD/CSD, where loads and motion are exchanged at each time step, does not make this periodic assumption and opens up new avenues of simulation to research. A major drawback to tightly-coupled CFD/CSD is an increase in computational cost. Different approaches are explored to reduce this cost as well as examine numerical implications in solutions from tightly and loosely-coupled CFD/CSD. A trim methodology optimized for tightly-coupled simulations is developed and found to bring trim costs within parity of loosely-coupled CFD/CSD simulations. Aerodynamic loading is found to be nearly similar for fixed controls. However, the lead-lag blade motion is determined to contain a harmonic in the tightly-coupled analysis that is not an integer multiple of the rotor speed. A hybrid CFD/CSD methodology employing the use of a free-wake code to model the far-field effects of the rotor wake is developed to aid in computational cost reduction. Investigation of this approach reveals that computational costs may be reduced while preserving solution accuracy. This work’s contributions to the community include the development of a trim algorithm appropriate for use in tightly-coupled CFD/CSD simulations along with a detailed examination of the physics predicted by loose and tight coupling for quasi-steady level flight conditions. The influence of the wake in such cases is directly examined using a modular hybrid coupling to a free-wake code that is capable of reduced cost computations.
205

Ets-insulin-bolus calculation promotes tighter blycaemic control for type 1 diabetics / Henry Louis Townsend

Townsend, Henry Louis January 2007 (has links)
Type 1 Diabetes is a dangerous and life-long disease for which its prevalence is global. Research has shown that tight glycaemic control of this disease significantly reduces the risks of developing several life threatening diabetic complications. The Ets-Insulin-Bolus Calculator (EIBC), inspired by the Ets concept (Equivalent Teaspoon Sugar), was primarily designed to assist type I diabetics in improving their blood glucose control. The EIBC has shown to improve the average blood glucose level of type 1 diabetics. The need for this study however is to determine whether the ET!3C promotes tighter glycaemic control for type 1 diabetics based on a more-in-depth numerical analysis. With the use of the latest technology in blood glucose monitoring, the CGMS from Medtronic, mathematical models expressing and rating blood glucose control have been proposed and derived in this study. A clinical trial with type 1 diabetics has also been conducted. The use of the models together with the clinical trial results have shown that the EIBC does in fact promote tighter glycaemic control for type 1 diabetics. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2007.
206

Ets-insulin-bolus calculation promotes tighter blycaemic control for type 1 diabetics / Henry Louis Townsend

Townsend, Henry Louis January 2007 (has links)
Type 1 Diabetes is a dangerous and life-long disease for which its prevalence is global. Research has shown that tight glycaemic control of this disease significantly reduces the risks of developing several life threatening diabetic complications. The Ets-Insulin-Bolus Calculator (EIBC), inspired by the Ets concept (Equivalent Teaspoon Sugar), was primarily designed to assist type I diabetics in improving their blood glucose control. The EIBC has shown to improve the average blood glucose level of type 1 diabetics. The need for this study however is to determine whether the ET!3C promotes tighter glycaemic control for type 1 diabetics based on a more-in-depth numerical analysis. With the use of the latest technology in blood glucose monitoring, the CGMS from Medtronic, mathematical models expressing and rating blood glucose control have been proposed and derived in this study. A clinical trial with type 1 diabetics has also been conducted. The use of the models together with the clinical trial results have shown that the EIBC does in fact promote tighter glycaemic control for type 1 diabetics. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2007.
207

Energy Bands Of Tlse And Tlinse2 In Tight Binding Model

Yildirim, Ozlem 01 September 2005 (has links) (PDF)
The electronical and structural properties of TlSe-type chain-like crystals are the main topic of this study. A computational method which is Tight Binding method is introduced and used to obtain the electronic band structure of TlSe and TlInSe2 . For both materials the partial and total density of states are calculated. The results are compared with the other theoretical results.
208

Cell adhesion proteins in different invasive patterns of colon carcinomas : a morphometric and molecular genetic study

Hahn-Strömberg, Victoria January 2008 (has links)
Colorectal carcinoma is the second most common type of cancer in both men and women in Sweden. Cancer of the colon and rectum are often considered together and their ten year survival rate is approximately 50 – 60 % depending on sex and location. Different histopathological characteristics of such cancers, including the complexity of growth, are of importance for prognosis. This thesis has compared different morphometric methods in order to achieve a quantitative and objective measurement of the invasive front of colon carcinoma. Since the growth pattern is dependent on the cell adhesiveness of different proteins we studied the distribution and localization of E-cadherin, Beta-catenin, Claudin 1,2,7 and Occludin as well as screened the genes for mutations. We found a perturbed protein expression of E-cadherin, Beta-catenin, Claudin 1,2,7 and Occludin in tumor sections compared to normal mucosa, but no relation to tumor volume or growth pattern could be seen. The tumor volume was found to be correlated to the growth pattern but not responsible to the perturbed protein expression. In the mutation screening we found a SNP in exon 13 the E-cadherin gene in the tumor, as well as in exon 2 of Claudin 1 and exon 4 of Claudin 7 in both tumor and normal mucosa. No correlation between mutations and growth pattern or tumor volume was found. In conclusion, this thesis shows that the computer image analysis with estimation of fractal dimension and number of free tumor cell clusters is superior to the semi quantitative visual grading of tumor invasive complexity. The aberrant expression of cell adhesion proteins in the tumor compared to normal mucosa as well as polymorphisms in the cell adhesion genes CLDN1 and CLDN7 in both tumor and normal mucosa can suggest that these aberrations are important in the tumorigenesis of colon carcinoma.
209

Mechanisms of blood retina barrier permeability during Bacillus cereus endophthalmitis

Moyer, Andrea Leigh. January 2008 (has links) (PDF)
Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 164-183.
210

Understanding the Management Control System Used by Hybrid Companies : A Case Study of IKEA and MIO.

Chaussée, Laury, Foray, Marine January 2018 (has links)
Due to the globalization, companies have to review their strategy permanently. In the same way, they need to choose the right management control system which will be in line with their strategy. Recent research has been made and it was highlighted that new strategies have been created to face up to the globalization and stay competitive. One of the new strategies is called “hybrid strategy”. It consists of combining the low-cost competitive advantage with the differentiation competitive advantage. By doing that, a company differentiates itself from its competitors with a special feature and, by the same time, has the lowest cost in its market. This new strategy came after the three generic strategies from Porter, which explains that a company needs to choose a competitive advantage if it wants to be profitable. The competitive advantages are either low-cost or differentiation. Most of the research made about the hybrid strategy was about the efficiency of this strategy. A very few research was made about the management of companies using the hybrid strategy. This is why in this paper, we would like to understand what kind of management control companies using this strategy have, more particularly do they use more a tight or a loose control. We also are looking at what kind of objectives companies using hybrid strategies have. If it is more a short-term or a long- term perspective and if it is more focused on monetary goals or non-monetary goals. For that, we compared the management control implemented in a hybrid company with the management controlled implemented in a low-cost company in Sweden. Four interviews were made at IKEA and MIO, which are two Swedish furniture companies in Sweden. To be able to draw a conclusion, we choose one hybrid company and one pure company to compare them. IKEA is the company using the hybrid strategy. These interviews gave us a lot of information to better understand the type of management control both companies have implemented. Then, the data were analyzed and discussed in order to highlight a potential conclusion. The gathered data suggest that hybrid companies and companies using a low-cost strategy have approximately the same management control system which is more tight control. About the objectives, both companies have the same. Indeed, IKEA and MIO have monetary goals and are more short-term goals oriented, at least for the lower level management. However, there are some differences that we can noticed. The first thing is that MIO uses more the informal control than IKEA. The second thing is that IKEA is more concerned by its employees. To conclude, even if IKEA and MIO are using two different strategies, they are very similar when looking to their management control.

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