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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.
501

Adult learning and social reconciliation: A case study of an academic programme at a Western Cape higher education institution

Van Reenen-Le Roux, Valdi Cathleen January 2012 (has links)
<p>Heterogeneous school communities are becoming more apparent under local and global conditions. A school community is more diverse and similar, not only racially but also in respect of&nbsp / economic, cultural, national and ethnic identities. Schools would require leaders who are mindful of the need for conflict sensitivity and social reconciliation within a globalising&nbsp / classroom.Through the lens of critical constructivism, I investigated the extent to which a higher education institution achieved the aims of the ACE in School Leadership, a continuing&nbsp / professional development programme. I relied upon a qualitative research approach to gather rich descriptive data from interviews conducted with nine school leaders who had graduated from the ACE School Leadership programme. The Literature Review is based on readings regarding critical constructivism, globalisation, conflict‐sensitivity and reconciliation.I found that the&nbsp / programme expanded the school leaders&rsquo / basic knowledge about conflict sensitivity and social reconciliation, but not sufficiently in terms of developing a critical consciousness to deal with&nbsp / conflict effectively. I concluded that conflict‐sensitive schools required school leaders that produced knowledge critically through a rigorous process of engagement and reflection. The ACE School Leadership programme had limitations in the extent to which it could prepare and equip school leaders in this regard.</p>
502

KATP Channel Phosphorylation: Mechanisms and Contribution to Vascular Tone Regulation by Vasodilating and Vasoconstricting Hormones and Neurotransmitters

Shi, Yun 03 December 2007 (has links)
Contractility of vascular smooth muscles (VSMs) in resistance arteries determines systemic blood pressure and blood supplies to local tissues, in which ATP sensitive K+ (KATP) channels play a role. The KATP channels that couple metabolic state to cellular activity are activated by multiple hormonal vasodilators and inhibited by vasoconstrictors. To understand the molecular mechanisms for the channel regulation by vasodilators, we studied the effects of β-adrenergic receptors on Kir6.1/SUR2B in HEK cells. Stimulation of β-adrenergic receptors activated the channels, which relied on the GS-protein, adenylyl cyclase, cAMP and PKA system. Using mutational analysis, we scanned all the putative PKA sites on Kir6.1 and SUR2B subunits and identified two residues (Ser1351 and Ser1387) in SUR2B critical for channel activation. In vitro phosphorylation experiments confirmed that Ser1387 but not Ser1351 was phosphorylated in isolated SUR2B peptides. Molecular modeling and molecular dynamics simulations reveal that phosphorylation at Ser1387 causes interdomain movements in SUR2B subunit. Blockage of the movements by engineering a disulfide bond across NBD2 and TMD1 eliminated the PKA-dependent channel activation. We also studied the molecular basis for the inhibition of vascular KATP channels by PKC. In the HEK expression system, we found that the Kir6.1/SUR2B channel but not the Kir6.2/SUR2B was drastically inhibited by PKC stimulation. We constructed Kir6.1/Kir6.2 chimeras and identified two critical protein domains for the Kir6.1 channel inhibition by PKC. The distal C-terminus was the direct target of PKC where multiple phosphorylation sites were identified. These phosphorylation sites were located in a short sequence with stereotypical sequence repeats. Mutation of any decreased the effects of PKC. Joint mutation of all of them prevented the channel inhibition by PKC. The proximal N-terminus is also involved in PKC effects without phosphorylation sites, suggesting it may play a role in channel gating. Thus, this thesis provides experimental evidence for the vascular KATP channel modulation by PKA and PKC. Phosphorylation of the Kir6.1 and SUR2B subunits by PKC and PKA produce inhibition and activation of the vascular KATP channel, respectively, which appears to be one of the molecular bases contributing to vascular tone regulation by both vasoconstricting and vasodilating hormones and neurotransmitters.
503

傾斜前面円柱先頭形状によるTSTO極超音速空力干渉の低減

小澤, 啓伺, OZAWA, Hiroshi, 花井, 勝祥, HANAI, Katsuhisa, 中村, 佳朗, NAKAMURA, Yoshiaki 05 January 2008 (has links)
No description available.
504

極超音速TSTO空力干渉流れ場における2物体間隔の空力加熱率への影響

西野, 敦洋, NISHINO, Atsuhiro, 石川, 尊史, ISHIKAWA, Takahumi, 北村, 圭一, KITAMURA, Keiichi, 中村, 佳朗, NAKAMURA, Yoshiaki 05 November 2005 (has links)
No description available.
505

Propiedades bioquímicas y biofísicas de ramnolípidos biotensioactivos

Sánchez Martínez, Marina 04 June 2010 (has links)
Los biotensioactivos son compuestos producidos por microorganismos que poseen actividad superficial, baja toxicidad, carácter biodegradable y efectividad a temperaturas y valores de pH extremos. Los ramnolípidos, son un tipo de biotensioactivos con interesantes actividades biológicas, que parecen estar relacionadas con su interacción con las membranas. En esta tesis doctoral se estudia la interacción de la fracción dirramnolipídica purificada de cultivos de Pseudomonas aeruginosa con membranas modelo y membranas biológicas, la interacción con albúmina de suero bovino, utilizada como proteína modelo, y por último, se evalúa el papel de este biotensioactivo en la estabilización de liposomas sensibles a pH y su aplicación en la introducción de compuestos en células animales. Para el desarrollo de este trabajo de investigación se han utilizado técnicas como calorimetría, FT-IR, difracción de rayos X, dispersión de luz dinámica y microscopía electrónica. / Rhamnolipids are bacterial biosurfactants produced by Pseudomonas spp. These compounds have been shown to present several interesting biological activities. It has been suggested that the interaction with the membrane could be the ultimate responsible for these actions. This thesis presents a detailed molecular level study of the dirhamnolipid interactions with artificial phospholipids membranes and biological membranas, and the dirhamnolipid interactions with bovine serum albumin, used as a general globular protein model. Furthemore, this work includes the characterization of phosphatidylethanolamine/diRL pH-sensitive liposomes described as efficient systems for cytoplasmic delivery of foreign compounds into living cells. It has been employed a number of physical techniques such as calorimetry, FTIR, small angle X-ray (SAX) diffraction and dynamic light scattering.
506

An innovative isolation device for aseismic design

Abdel-Kareem Moustafa, Mohammed Ismail 09 November 2009 (has links)
Basado en la idea de reducir la demanda sísmica en lugar de aumentar la capacidad resistente de las estructuras, el aislamiento sísmico es un método simple para mitigar o reducir los posibles daños producidos por los terremotos. La correcta aplicación de esta tecnología conduce a un mejor comportamiento de las estructuras, que sigue siendo esencialmente elástico durante los terremotos de gran magnitud. El núcleo de esta tecnología es el aislador. La mayoría de los aisladores sísmicos disponibles en la actualidad siguen teniendo limitaciones prácticas que impiden que funcionen según lo previsto e imponen restricciones a su uso efectivo y al nivel de protección proporcionado. En esta Tesis, se presenta un aislador sísmico avanzado llamado "roll-n-cage (RNC)". Se propone investigar su eficiencia a través de simulación numérica, en un intento de crear un sistema de aislamiento sísmico práctico, efectivo y económico, que tiene por objeto resolver los principales inconvenientes de los actuales sistemas de aislamiento sísmico, manteniendo sus principales ventajas. Este aislador incorpora aislamiento, disipación de energía, amortiguamiento y capacidad de fuerza recuperadora en una sola unidad. Además, ofrece una resistencia al viento significativa y una amplia gama de flexibilidad horizontal, por lo que es adecuado para proteger las estructuras de masa ligera, moderada y grande, así como para proteger equipos sensibles, hardware y / o antigüedades alojados en edificios. Por otra parte, las cuestiones relativas a la viabilidad, los costes de construcción y la disponibilidad de materiales, reducción o prevención de las respuestas de torsión y la resistencia a la elevación son abordados a fondo durante el diseño del aislador RNC. El aislador RNC propuesto es descrito en profundidad y sus principios de funcionamiento son presentados en detalle. La caracterización mecánica del dispositivo se ha llevado a cabo por medio de un código computacional sofisticado que simula la respuesta de los dispositivos como si estuvieran sujetos a una máquina de pruebas reales. A través de este esquema, se consigue analizar numéricamente el comportamiento del aislador RNC bajo el efecto simultáneo de cargas horizontales y verticales, como se da típicamente en situaciones prácticas. Además, se presenta una descripción matemática de las principales características asociadas a la rodadura de los aisladores RNC. Asimismo se obtiene un modelo matemático para describir en una forma razonable y manejable la relación fuerza desplazamiento exhibida por el aislador de RNC. Para evaluar la viabilidad del aislador RNC y para comprobar su capacidad para proteger los sistemas estructurales y no estructurales de los riesgos sísmicos, el dispositivo se implementa numéricamente en una variedad de estructuras con masas ligeras y grandes, además de en equipos sensibles alojados en los pisos superiores de dichas estructuras. Para extraer conclusiones de carácter relativamente general sobre el funcionamiento del aislador RNC, se estudia una amplia gama de terremotos y de características y propiedades de los aisladores y de las estructuras.Los resultados numéricos revelan que el aislador RNC propuesto puede reducir la respuesta sísmica frente a un amplio rango de excitaciones sísmicas, mientras que exhibe un rendimiento robusto para una gran variedad de estructuras. La Tesis incluye como apéndice un estudio en profundidad sobre el modelo de histéresis de Bouc-Wen. El estudio contiene una revisión de los primeros y últimos avances y aplicaciones de este modelo, que es ampliamente utilizado en la descripción de fenómenos de histéresis en las estructuras. / Based on the concept of reducing seismic demand rather than increasing the earthquake resistant capacity of structures, seismic isolation is a surprisingly simple approach to mitigate or reduce earthquake damage potential. Proper application of this complex technology leads to better performing structures that will remain essentially elastic during large earthquakes. The core of this technology is the isolator. Most currently available seismic isolators still have practical limitations causing them not to function as anticipated and impose restrictions to their proper use and to the provided protection level. In this dissertation, an advanced rolling-based seismic isolator, named roll-n-cage (RNC) isolator, is proposed and investigated via numerical simulation as an attempt to create a practical, effective, and economic seismic isolation system that aims to fix the main drawbacks of the current seismic isolation systems while keeping their main advantages. This isolator incorporates isolation, energy dissipation, buffer and restoring force mechanisms in a single unit. Further, it offers a significant wind resistance and a great range of horizontal flexibility making it ideal to protect light, moderate and heavy mass structures as well as precious housed motion-sensitive equipment, hardware and/or antiquities. Moreover, issues related to practicality, construction costs and material availability, reducing or preventing torsional responses and uplift resistance are thoroughly addressed during the RNC bearing design.The proposed RNC isolator is deeply described and its principles of operation are extensively highlighted. The mechanical characterization of the device has been carried out by means of a sophisticated computer code in a machine-like environment, which accurately simulates the response of the device subjected to a real testing machine. Through this machine-like environment, a general scheme is followed to numerically examine the behavior of the RNC isolator under simultaneous horizontal and vertical loads as in typical practical situations. Further, a mathematical description of the main features associated to rolling of the RNC isolator is presented. An input-output mathematical model is obtained to describe in a reasonable and manageable form the force-displacement relationship exhibited by the RNC isolator.To assess the feasibility of the RNC isolator and to check its ability to protect structural and nonstructural systems from seismic hazards, it is numerically implemented to a variety of structures having light to heavy masses, in addition to motion-sensitive equipment housed in upper building floors. Further, and to draw relatively general conclusions about the performance of the RNC isolator, a wide range of ground motions, isolator characteristics and structural properties is considered. The numerical results reveal that the proposed RNC isolation bearing can mitigate the seismic responses under a variety of ground motion excitations while exhibiting robust performance for a wide range of structures. The dissertation is appended with an in-depth survey, that contains a review of the past, recent developments and implementations of the versatile Bouc-Wen model of smooth hysteresis, which is used extensively in modeling the hysteresis phenomenon in the dynamically excited nonlinear structures. This survey is the first of its kind about the model since its origination more than 30 years ago. The objective is to present some of the popular approaches that have utilized and/or developed that model to capture the hysteretic behavior offered by a variety of nonlinear systems. Then, the evaluation of their results and contributions (if any) is carried out to highlight their assets and limitations and to identify future directions in this research area.
507

System Contingency Study with Power Flow Tracing Method for Congestion Management

Shen, Wan-Bao 27 June 2011 (has links)
The ¡§Congestion Management¡¨ (CM) always has been an outstanding and major problem in power system operation. To solve this problem, experts compose solutions in a wide variety. This thesis, based on the equivalent current, applies the Equivalent Current Injection (ECI) concept and circuit parameters to derive the Power Flow Tracing Method (PFTM) . By means of this method we can get a Sensitive Matrix (SM), which is also called the Contribution Matrix (CM), to show the linear relationship between the input power and tidal current discharge of each generator set, with the linear relationship we can derive the mathematic model of treating the congestion problem discussed in this thesis. Combining the Predictor-Corrector Interior Point Algorithm (PCIPA), we can manipulate the change of each generator set in the prospective of solving the congestion problem resulting from the system contingency (SC). The thesis performed various simulations for the IEEE 30 Bus system. Regarding the power contingencies, the solutions of the power-congestion problems can be resulted from the following incidents: heavy load addition, transmission line tripped, generator malfunction as well as the multi-contingencies, etc., which can all be solved with solutions within reasonably restricted domains. We can thus verify the effectiveness of the method .
508

On delay-sensitive communication over wireless systems

Liu, Lingjia 15 May 2009 (has links)
This dissertation addresses some of the most important issues in delay-sensitive communication over wireless systems and networks. Traditionally, the design of communication networks adopts a layered framework where each layer serves as a “black box” abstraction for higher layers. However, in the context of wireless networks with delay-sensitive applications such as Voice over Internet Protocol (VoIP), on-line gaming, and video conferencing, this layered architecture does not offer a complete picture. For example, an information theoretic perspective on the physical layer typically ignores the bursty nature of practical sources and often overlooks the role of delay in service quality. The purpose of this dissertation is to take on a cross-disciplinary approach to derive new fundamental limits on the performance, in terms of capacity and delay, of wireless systems and to apply these limits to the design of practical wireless systems that support delay-sensitive applications. To realize this goal, we consider a number of objectives. 1. Develop an integrated methodology for the analysis of wireless systems that support delay-sensitive applications based, in part, on large deviation theory. 2. Use this methodology to identify fundamental performance limits and to design systems which allocate resources efficiently under stringent service requirements. 3. Analyze the performance of wireless communication networks that takes advantage of novel paradigms such as user cooperation, and multi-antenna systems. Based on the proposed framework, we find that delay constraints significantly influence how system resources should be allocated. Channel correlation has a major impact on the performance of wireless communication systems. Sophisticated power control based on the joint space of channel and buffer states are essential for delaysensitive communications.
509

The Impact Of Sensitive Science & Technology Control Mechanism Against The Competitive Advantages of Taiwan Semiconductor Industry.

Wu, Hsueh-Fung 10 July 2006 (has links)
The 8-inch wafer Fab. landing China or not evoked highly concerned in the worldwide, and even evoked the misdoubt if Taiwan clash with Wassenar Agreements . On New Year¡¦s Day, President Chen Shei-Ben reiterated the Policy of Economy and Trade across the Taiwan Straits, ¡§Proactive liberalization with effective management¡¨, which also evoked controversy in the worldwide. While UMC (United Microelectronic Corporation) ¡¥s He-Jan investment was been debating hotly, we considered if it also had great effect of production race between Taiwan and China, besides business benefits. Moreover, we considered if it resulted in the technology illegal landing, and conflicted with Wassenar Agreements, by avoiding to threaten the national security. If Taiwan was a launching pad of America high tech to China, it would cause other high techs importing forbiddance from America. Because of that, Taiwan gets more a loss than gains. Suppose ¡§Economic globalization¡¨ is the lifeblood of Taiwan; The semiconductor industry is not only holding on the advantages of past , but also trying to approach to the market. Furthermore, it should create production competitiveness. The government should follow the market rules, develop the reciprocal relationship with business and reach the goal of looking after both sides, economic developing and national security. In this study, it expects to discuss the influence of The Sensitive Scientific Technology Draft Bill legislation of funding, technology, equipment, brain-import abridged in semiconductor production in Taiwan to the competitive advantage of production; (1) Understanding the status and meaning of The Sensitive Scientific Technology Draft Bill in Taiwan. (2) Does tech-import controlling of The Sensitive Scientific Technology Draft Bill in Taiwan has connecting to international relative laws? (3) Analyzing the impact of the protect mechanism of The Sensitive Scientific Technology Draft Bill to competitive advantage of semiconductor industry. The first study step is to comparing analyze the aims, effects, targets of international relative laws by documents study, especially according to the international relative laws of high-tech import controlling, for example, the administration rules and complement actions of COCOM and Wassenar Agreements, for understanding the reasonable and objective of The Scientific Technology Draft Bill (The Sensitive Scientific Technology Draft Bill). Moreover, base on profound interview with business to processing the situational analysis of business, production, people, society, government and the national security. This study conclusion and the suggestions from business experience can offer the reference resources for lawmaking and revising.
510

On the effect of INQUERY term-weighting scheme on query-sensitive similarity measures

Kini, Ananth Ullal 12 April 2006 (has links)
Cluster-based information retrieval systems often use a similarity measure to compute the association among text documents. In this thesis, we focus on a class of similarity measures named Query-Sensitive Similarity (QSS) measures. Recent studies have shown QSS measures to positively influence the outcome of a clustering procedure. These studies have used QSS measures in conjunction with the ltc term-weighting scheme. Several term-weighting schemes have superseded the ltc term-weighing scheme and demonstrated better retrieval performance relative to the latter. We test whether introducing one of these schemes, INQUERY, will offer any benefit over the ltc scheme when used in the context of QSS measures. The testing procedure uses the Nearest Neighbor (NN) test to quantify the clustering effectiveness of QSS measures and the corresponding term-weighting scheme. The NN tests are applied on certain standard test document collections and the results are tested for statistical significance. On analyzing results of the NN test relative to those obtained for the ltc scheme, we find several instances where the INQUERY scheme improves the clustering effectiveness of QSS measures. To be able to apply the NN test, we designed a software test framework, Ferret, by complementing the features provided by dtSearch, a search engine. The test framework automates the generation of NN coefficients by processing standard test document collection data. We provide an insight into the construction and working of the Ferret test framework.

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