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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.
681

Role of Snx9 in the Regulation of Mitochondrial Morphology

Magosi, Lerato E. 27 June 2012 (has links)
Mitochondria are dynamic; they alter their shape through fission, fusion and budding of vesicles. Mitochondrial vesicles serve as a quality control mechanism enabling these organelles to rid themselves of damaged lipids and proteins. Dysregulation in mitochondrial dynamics and quality control have been linked to Parkinson’s Disease, making the identification of molecules requisite for these processes a priority. We identified the endocytic protein, Sorting nexin 9 (Snx9) through a genome wide siRNA screen for genes which substantially alter mitochondrial morphology and therefore are important for its maintenance. In this work, the role of Snx9 in mitochondrial morphology is examined. Ultrastructural imaging of mitochondria within cells silenced for Snx9 revealed unbudded vesicles along a hyperfused mitochondrial reticulum suggesting a role for Snx9 in the release of these vesicles. The vesicular profiles contained concentric membranous whorls enriched for neutral lipids. Localization studies suggest the Parkinson’s disease genes, Parkin and Vps35 localize to the unbudded profiles.
682

p97 Negatively Regulates NRF2 by Extracting Ubiquitylated NRF2 from the KEAP1-CUL3 E3 Complex

Tao, Shasha, Liu, Pengfei, Luo, Gang, Rojo de la Vega, Montserrat, Chen, Heping, Wu, Tongde, Tillotson, Joseph, Chapman, Eli, Zhang, Donna D. 15 April 2017 (has links)
Activation of the stress-responsive transcription factor NRF2 is the major line of defense to combat oxidative or electrophilic insults. Under basal conditions, NRF2 is continuously ubiquitylated by the KEAP1-CUL3-RBX1 E3 ubiquitin ligase complex and is targeted to the proteasome for degradation ( the canonical mechanism). However, the path from the CUL3 complex to ultimate proteasomal degradation was previously unknown. p97 is a ubiquitin-targeted ATP-dependent segregase that extracts ubiquitylated client proteins from membranes, protein complexes, or chromatin and has an essential role in autophagy and the ubiquitin proteasome system ( UPS). In this study, we show that p97 negatively regulates NRF2 through the canonical pathway by extracting ubiquitylated NRF2 from the KEAP1-CUL3 E3 complex, with the aid of the heterodimeric cofactor UFD1/NPL4 and the UBA-UBX containing protein UBXN7, for efficient proteasomal degradation. Given the role of NRF2 in chemoresistance and the surging interest in p97 inhibitors to treat cancers, our results indicate that dual p97/NRF2 inhibitors may offer a more potent and long-term avenue of p97-targeted treatment.
683

Acceptance Tests – FAT & SAT : An Empirical Case Study of Utility Poles

Al Farra, Hussni January 2016 (has links)
The overall purpose of this project is to devise improved quality acceptance procedures to examine quality characteristics of utility poles at the factory of the supplier (FAT) and on-site upon receipt by the customer (SAT). To that end, the thesis draws upon available standards, literature, and industry practices regarding wood, fiberglass and steel poles. As far as the design of the research, a single case study of a major power company was chosen. Then, a data collection plan was developed in order to build upon the existing knowledge found in the literature, and upon the data that can be collected from three of the Company’s suppliers, in addition to the Technical Research Institute of Sweden (SP). Documents’ analysis, interviews, observations, and a survey were the tools of that plan. It was found that criteria, inspection and test methods of wood poles are all sufficiently covered in the standards and the literature; for wood is the most commonly used material for utility poles. Next, in coverage of research, are the steel poles; while there is currently no standard that covers fiberglass utility poles. Indeed, quality characteristics, criteria, and acceptance procedures can altogether form parts of a sustainable solution, as long as the quality is managed as a process whether at the Company’s end or at the fabrication sites; that is especially true if there is some form of backward partnership between the Company and its suppliers.
684

An Investigation of the Perception of Delivered Quality at Different Levels of Organizational Hierarchy in Services

Getty, Juliet M. (Juliet Margolin) 12 1900 (has links)
The overall purpose of this research was to add to existing theory of quality pertaining to the service provider's perception of quality. Quality in the service industry is difficult to assess because of the intangible, heterogeneous and labor intensive nature of services. In addition, personnel have varying perceptions of delivered quality based on their position within the organizational hierarchy. This study enhanced the Service Quality Model developed by Zeithaml, Berry, and Parasuraman (1988). An additional gap ("gap 6") was hypothesized and investigated. This gap describes the differences in perceived delivered quality by employees at different organizational levels (e.g., managerial, supervisory, and non-management employees) across different market segments. The researcher proposed that "gap 6" has a significant impact on total perceived delivered quality. The survey instrument addressed five dimensions of overall quality: tangibles, reliability, responsiveness, assurance, and empathy. The survey was administered to employees from hotels representing three market segments located within the same metropolitan area and managed by the same company. A 3 X 3 factorial design was used with three organizational levels (managers, supervisors, and hourly employees) and three lodging market segments (luxury, business-traveller, and long-term/suite). Data analyses included descriptive statistics, analysis of variance (ANOVA), and Tukey's Multiple Comparison Test.
685

Economic Statistical Design of Inverse Gaussian Distribution Control Charts

Grayson, James M. (James Morris) 08 1900 (has links)
Statistical quality control (SQC) is one technique companies are using in the development of a Total Quality Management (TQM) culture. Shewhart control charts, a widely used SQC tool, rely on an underlying normal distribution of the data. Often data are skewed. The inverse Gaussian distribution is a probability distribution that is wellsuited to handling skewed data. This analysis develops models and a set of tools usable by practitioners for the constrained economic statistical design of control charts for inverse Gaussian distribution process centrality and process dispersion. The use of this methodology is illustrated by the design of an x-bar chart and a V chart for an inverse Gaussian distributed process.
686

A longitudinal study of customers perceptions of their confidence in, and satisfaction with, the South African Sugar Association Cane Testing Service division

Naidoo, Gonaseelan January 2004 (has links)
Submitted in partial fulfilment of the requirements for the degree of Master of Business Administration in the Business Studies Unit, Durban Institute of Technology, 2004. / Customer satisfaction is a critical component of a business' competitive strategy. The Cane Testing Service (CTS) division of the South African Sugar Association is operating in a deregulated market environment and thus has to ensure that customers are always satisfied with the quality of service received from CTS. This study aimed to establish the change in customer satisfaction levels between 1998 and 2003. The study set out to determine customer satisfaction levels with specific customer groupings of combined millers and growers, millers-only and growers-only of all fourteen Mill Group Boards. The study investigated customer satisfaction levels for each of the sixteen service characteristics for the fourteen Mill Group Boards. Regular measurement of customer satisfaction allows CTS to continuously improve the levels of customer satisfaction and thereby minimise the threat to CTS of competitors entering the sugar industry laboratory services market. Customer satisfaction levels were determined by conducting a longitudinal, quantitative survey on one hundred and sixty-eight miller and grower members of all Mill Group Boards using the CTS developed questionnaire, containing CTS and customer verified service attributes. I I I The 2003 study shows a statistically significant improvement in customer satisfaction levels with CTS service delivery across all customer groupings in comparison with the 1998 customer satisfaction levels. The specific Mill Group Board analyses shows an improvement in customer satisfaction levels for twelve of the fourteen boards. Specific strategies are to be developed for those boards and service attributes that did not show an improvement. It is recommended that CTS customer surveys be conducted every three years and the Balanced Scorecard management tool be used to monitor the effectiveness of customer improvement strategy implementation. It is proposed that future research consider benchmarking CTS service delivery against other similar service providers and that focus groups be employed to obtain feedback from key customers. / M
687

Protein Quality Control at the Inner Nuclear Membrane – The Asi complex in Saccharomyces cerevisiae

Pantazopoulou, Marina January 2016 (has links)
The nuclear envelope is a barrier comprised of outer and inner membranes that separate the cytoplasm from the nucleoplasm. The outer (ONM) and inner (INM) membranes have different physical characteristics and protein compositions. In contrast to the extensive data available on the protein quality control processes operating in the cytoplasm, endoplasmic reticulum and the nucleoplasm, the mechanisms controlling protein turnover at the INM are poorly documented. The work presented in this thesis focuses on Asi1, Asi2 and Asi3, three bona-fide integral INM proteins of the yeast Saccharomyces cerevisiae. By contrast to mammalian cells, yeast progress through the cell cycle with a closed mitosis, that is cells divide in the absence of the cyclical fragmentation/reassembly of the nuclear membrane. Consequently, examining the processes affecting the stability of the Asi proteins in yeast may provide useful paradigms for understanding the turnover of INM components in non-dividing, terminally differentiated and post-mitotic cells of metazoan origin.The results have contributed to the elucidation of the biological function of Asi1 and Asi3, which are homologous proteins with C-terminal RING domains. Asi1 and Asi3 function together as a dimeric E3 ubiquitin ligase complex that operates with ubiquitin conjugating enzymes Ubc6 and Ubc7. The Asi1/3 complex ubiquitylates transcription factors Stp1 and Stp2 when they gain inappropriate access to the nucleus in the absence of SPS-sensor activation. Intriguingly, the Asi1/3 complex also mediates the turnover of multiple membrane proteins that primarily localize to other cell membranes. This latter finding indicates that the barrier function of nuclear pore complexes is not as tight as previously thought. Consistently, asi1 null mutations are synthetic lethal when introduced into hrd1Δ ire2Δ cells with compromised ER-associated degradation (ERAD) and unfolded protein response (UPR) pathways. Together the results define Asi1/3 as components of a novel quality control pathway operating in association with the INM that acts to safeguard the identity and maintain the function of the nuclear compartment. Asi1 and Asi2 exhibit rapid turnover and their turnover is ubiquitin-dependent, exhibiting a clear requirement for Ubc7. The ubiquitylated forms of Asi1 and Asi2 are degraded by nuclear-localized proteasomes; the ubiquitylated forms exhibit enhanced stability in sts1-2 mutants. Asi1 turnover requires Cue1, the AAA ATPase Cdc48 and co-factor Ubx1. Asi1 turnover occurs unimpeded in cells lacking a functional Asi1/3 complex and in cells lacking Doa10, an E3 ligase complex also known to function at the INM. Consequently, Asi1 is subject to a quality control pathway associated with INM but that is distinct from the Asi1/3 and Doa10 INM- associated degradative (INMAD) pathways. This thesis documents work that clearly demonstrates that the INM is a highly dynamic structure that possesses multiple and active quality control pathways. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>
688

A 'Biorelevant' Approach for Accelerated In Vitro Release and In Vitro-In Vivo Relationship of a Biodegradable, Naltrexone Implant

Iyer, Sunil S. 01 January 2006 (has links)
Characterization of in vitro and in vivo drug release profiles constitutes an important step in developing and optimizing an effective, long acting delivery system for naltrexone. Accelerated in vitro methods are also important for quality assurance of manufactured dosage forms. For drug release testing of sustained release parenteral dosage forms, the modified USP Apparatus 4 (flow-through cell) has been recommended by the The Fédération Internationale Pharmaceutique/American Association of Pharmaceutical Scientists (FIP/AAPS) Guidelines. Details on such studies however, are generally not found in the literature. To incorporate 'biorelevance' to implant drug release studies, this research investigated an approach to apparatus design and media selection that is significantly different from conventional dissolution studies involving oral dosage forms.Biodegradable implants of naltrexone were obtained from Durect Corporation, USA. A modified Hanks' Balanced Salts Solution was characterized as a 'biorelevant' medium for in vitro drug release studies. Naltrexone was found to be sufficiently stable in the medium, as determined by a stability-indicating High Performance Liquid Chromatography (HPLC) assay. A miniature, cell-culture, capillary system was modified and tested as a 'biorelevant' alternative to the modified flow-through apparatus, to mimic significant barriers to drug release that would be expected in vivo. The in vitro release profiles generated up to 3 months using both devices indicated considerable (2-fold) variation in rates, as expected from the difference in media flow characteristics. An implantation study in a dog was conducted to determine which of the two devices could provide a better simulation of the in vivo conditions. Analysis of in vivo samples was carried out by a Liquid Chromatography-Tandem Mass Spectrometry (LC-MS-MS) method that also employed a molecular model approach to demonstrate the absence of Internal Standard Deuterium Isotope Effects. A good In vitro-In vivo Correlation (IVIVC) resulted from both devices; however, the capillary device provided a superior simulation for the lag-time in absorption. The accelerated study at 45°C and 55°C established a predictable increase in release rates (2-fold and 4-fold increases, respectively). The approach described in this work could provide the basis for future method modification of in vitro drug release tests of subcutaneous implants.
689

Improved Fabrication and Quality Control of Substrate Integrated Microelectrode Arrays

Zim, Bret E. 05 1900 (has links)
Spontaneously active monolayer neuronal networks cultured on photoetched multimicroelectrode plates (MMEPs) offer great potential for use in studying neuronal networks. However, there are many problems associated with frequent, long-term use of MMEPs. The major problems include (1) polysiloxane insulation deterioration and breakdown, (2) and loss of gold at the gold electroplated indium-tin oxide (ITO) electrodes. The objective of this investigation was to correct these major problems. Quality control measures were employed to monitor MMEP fabrication variables. The phenotypes of polysiloxane degradation were identified and classified. Factors that were found to contribute most to insulation deterioration were (1) moisture contamination during MMEP insulation, (2) loss of the quartz barrier layer from excessive exposure to basic solutions, and (3) repetitive use in culture. As a result, the insulation equipment and methods were modified to control moisture-dependent insulation deterioration, and the KOH reprocessing solution was replaced with tetramethylguanidine to prevent damage to the quartz. The problems associated with gold electroplating were solved via the addition of a pulsed-DC application of gold in a new citrate buffered electroplating solution.
690

Un-tensioned pullout tests to predict the bond quality of different prestressing reinforcements used in concrete railroad ties

Arnold, Matthew Lukas January 1900 (has links)
Master of Science / Department of Civil Engineering / Robert J. Peterman / An experimental testing program was conducted at Kansas State University (KSU) to test the bond characteristics of various 5.32-mm-diameter steel wires and smaller diameter (less than 0.5 in.) strands used in prestressed concrete railroad ties. A total of 13 wires and six strands produced by seven different steel manufacturers were used during this testing. Since no wire bond pullout test currently exists, one was developed and its validity tested. This un-tensioned pullout test could serve as a quality control test similar to the standard test for strand bond (ASTM A1081) that has been developed for pretensioned strands. This strand test is currently not verified for strands less than 0.5-in. in diameter, so the procedure was also scrutinized using strands common in the concrete railroad tie industry. Some of the wires and strands contained surface indentations. It is generally accepted that indentations in the reinforcements improve the bond between the steel and concrete. To further complicate the issue, reinforcements with different surface conditions (rust, oils, lubricants) are allowed to be used in the concrete ties which further affects the bond quality of the reinforcements. However, no standardized indentation patterns (shape, size, depth of indent, etc.) or surface conditions (degree of rusting, amount of surface lubricants, etc.) are utilized by all wire and strand manufacturers. Thus, the corresponding bond behavior of these different reinforcements when placed in various concrete mixtures, in terms of average transfer lengths and typical variations, is essentially unknown. The purpose of this testing program was to develop (in the case of wires) or verify/develop (in the case of strands) a pullout testing procedure predictive of the reinforcement’s bond performance in a prestressed application. The test should be relatively inexpensive, demonstrably repeatable, and easily reproducible. Results from the un-tensioned pullout tests were compared to transfer length measurements from accompanying pretensioned concrete prisms in the lab. Additionally, pullout tests and transfer length measurements were obtained at an actual concrete railroad tie manufacturing plant. The obtained data was compared to the lab data and analyzed to further understand the relationship between un-tensioned pullout tests and pretensioned concrete members.

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