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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.
11

Análisis genético de paragangliomas de cabeza y cuello

Sevilla García, María Agustina 26 May 2007 (has links)
Los paragangliomas (PGL) de cabeza y cuello son tumores poco frecuentes que pueden ser esporádicos o familiares. En los PGL familiares hasta el momento se han identificado 4 locus cromosómicos relacionados con la enfermedad: 11q23 (PGL1), 11q13 (PGL2), 1q21 (PGL3) y 1p36.1p35 (PGL4). No obstante, el hecho de tener la mutación no significa necesariamente desarrollar la enfermedad, ya que su penetrancia es del 70% a los 50 años de edad. Por otra parte, los pacientes con PGL deben ser examinados genéticamente con el fin de determinar si la enfermedad es hereditaria y en ese caso extender a sus familiares el estudio genético, lo que conlleva un coste importante. La presente tesis trata de arrojar luz sobre las causas por las que en portadores de la mutación se desarrolla o no la enfermedad, así como las bases clínicas para realizar en primer lugar el estudio del gen más probablemente mutado, lo que ahorraría costes en el estudio de un paciente al evitar el análisis de los genes menos probable Con la primera finalidad, se realizó en primer lugar un cribaje de las alteraciones cromosómicas mediante la técnica de microarray-CGH, estudiándose además las mutaciones en los genes SDHB, SDHC, SDHD, RET Y VHL en pacientes que presentaban PGL de cabeza y cuello. Una vez realizado el análisis mutacional de todos los genes implicados en los PGLs familiares y establecida la correlación con los datos clínicos, se estudió la secuencia ideal de análisis de los distintos genes con la finalidad de estudiar primero aquel gen que tuviera probabilidad de estar mutado de acuerdo con las características clínicas.Del total de 72 pacientes estudiados, únicamente se objetivó mutación germinal patogénica en los genes SDHB o SDHD en 26 (36%) casos: 14 casos con mutación en el gen SDHB, y 12 en el SDHD. 14 de estos paciente con mutación germinal eran casos familiares y 12 supuestamente esporádicos ("familiares ocultos") con mutación en los genes SDH, lo que contribuyó a conocer el carácter hereditario de la enfermedad. Se observaron cuatro mutaciones no descritas previamente en la literatura, y por el contrario no se objetivaron mutaciones o delecciones en exones de los genes SDHC, VHL o RET. Estos datos sugieren que los tumores múltiples y con historia familiar positiva son altamente predictivos para mutaciones en el gen SDHD. De igual modo, los tumores únicos y malignos se asocian con mutaciones en el gen SDHB. En los pacientes analizados mediante microarrays-CGH se detectaron anomalías en el 45% de los casos, consistentes más frecuentemente en pérdidas cromosómicas (84%) que en ganancias. Los cromosomas que presentaban pérdidas o delecciones con mayor frecuencia eran el 1, el 11, el 22 y el 21. Los tumores que presentaban mutación germinal en los genes SDH tenían más alteraciones cromosómicas. La metodología utilizada en la realización del trabajo es adecuada desde la perspectiva del rigor científico, tanto en lo que se refiere a los procedimientos de laboratorio (microarrays-CGH, estudio de las mutaciones, etc.), el tamaño muestral (muy grande dada la rareza de la enfermedad) y el análisis estadístico de los resultados, incluyendo las correlaciones clínico-patológicas. Así, se comprobó la utilidad de los parámetros clínicos (edad <40 años, sexo varón, el hecho de presentar un feocromocitoma o tumores múltiples o presentar antecedentes familiares) para ayudar a predecir las mutaciones y su utilidad para priorizar el análisis de las mismas en los genes SDH y reducir los costes en el estudio de los pacientes con PGL.
12

Study on the Electronic Properties of In0.22Ga0.78As/GaAs Single Quantum Wells

Lian, Jau-Rung 29 June 2004 (has links)
We haved studied the magneto-transport properties of two dimensional electron gas (2DEG) in Si £_-doped In0.22Ga0.78As/AlGaAs single quantum wells ( QWs ) by using Shubnikov-de Haas ( SdH ) measurements . From the SdH measurement , we can clearly observe the SdH oscillations and obtain the SdH frequencies. It indicates the 2DEG in these QWs was confirmed . We also obtain the deep level binding energies¡G 104.4 meV and 9.6 meV for sample 1 and 50.2meV for sample2 by T-dependent Van der Pauw Hall effect measure- ment at magnetic field 0.3T. The difference of these two samples was the In0.1Ga0.9As layer of sample 2 was inserted between In0.22Ga0.78As well and the GaAs spacers . So in this paper , we tried to propose a model to interpret the deep-level traps in the QWs and studied the effect of In0.1Ga0.9As inserted-layer on the In0.22Ga0.78As/GaAs Single Quantum Wells.
13

Development of a web-based interface for SDH

Reimann, Kalle January 2012 (has links)
Ericsson in Linköing has a test environment for testing telecommunications equipment. New equipment was recently purchased to the fiber-optic network in the test environment, but the management system for the new equipment lacked a web based interface for users without special access to the system. The purpose of this thesis is to implement such an interface. A web site based on Python and Django was built where users can search for circuits, with or without search filters, and get information about the matching circuits. The website has been live for two months and no major issues have appeared.
14

Improvements on Scientific System Analysis

Grupchev, Vladimir 01 January 2015 (has links)
Thanks to the advancement of the modern computer simulation systems, many scientific applications generate, and require manipulation of large volumes of data. Scientific exploration substantially relies on effective and accurate data analysis. The shear size of the generated data, however, imposes big challenges in the process of analyzing the system. In this dissertation we propose novel techniques as well as using some known designs in a novel way in order to improve scientific data analysis. We develop an efficient method to compute an analytical query called spatial distance histogram (SDH). Special heuristics are exploited to process SDH efficiently and accurately. We further develop a mathematical model to analyze the mechanism leading to errors. This gives rise to a new approximate algorithm with improved time/accuracy tradeoff. Known MS analysis systems follow a pull-based design, where the executed queries mandate the data needed on their part. Such a design introduces redundant and high I/O traffic as well as cpu/data latency. To remedy such issues, we design and implement a push-based system, which uses a sequential scan-based I/O framework that pushes the loaded data to a number of pre-programmed queries. The efficiency of the proposed system as well as the approximate SDH algorithms is backed by the results of extensive experiments on MS generated data.
15

Allsidighet och saklighet : En kvalitativ studie om hur Jesu Kristi Kyrka av Sista Dagars Heliga och Jehovas vittnen representeras i läroböcker / Versatility and objectivity : a qualitative study of how the Church of Jesus Christ of Latter-day Saints and Jehovah’s Witnesses are represented in school books

Lundqvist, Marcus January 2022 (has links)
Syftet med denna uppsats har varit att undersöka hur Jehovas vittnen och Jesu Kristi kyrka avSista Dagars Heliga representeras i läroböcker ämnade för gymnasiet och högstadiet efter 2011.Studien har även ämnat undersöka hur beskrivningarna av rörelserna skiljer sig åt, och i vilkasammanhang religionerna placeras i läroböckerna. Materialet till undersökningen består av nioläroböcker, där fem är ämnade för gymnasiet och fyra för högstadiet. Undersökningen harutgått från en kvalitativ innehållsanalys och ett teoretiskt ramverk som grundar sig imatrisindelningen som islamologen Jonas Otterbeck har konstruerat i samband med hansläromedelsgranskningar. Matrisen utgår från att läroböckers skildringar har en tendens att varaonyanserade, utelämna väsentlig information och innehålla ett tendensiöst urval, något somresulterar i att religioner framställs ogynnsamt. Utöver det har studien också utgått från KjellHärenstams begrepp allsidighet och saklighet som menar att läroböckerna ska återge en allsidigbild av en religion, samt att inte viss information får utelämnas eller framhävas på ett sådantsätt att religionen framställs missvisande.Undersökningen visade att rörelserna skildras översiktligt i samtliga böcker och att fakta harutelämnats, något som har lett till att vissa verk återger en felaktig och förvirrande bild avrörelserna. Dels förekommer det i några av verken att rörelserna återges på ett tendensiöst sätt,som leder till att rörelserna antingen framställs positivt eller negativt. Tillskillnad från JesuKristi kyrka av Sista Dagars Heliga framställdes Jehovas vittnen som en homogen rörelse.Dessutom betonades skillnaderna mellan andra kristna kyrkor och Jehovas vittnen meringående än med Jesu Kristi Kyrka av Sista Dagars Heliga och andra kristna samfund.Anmärkningsvärt visade också studien att flertalet av läroböckerna skildrade rörelserna isamband med nyreligiösa rörelser och inte med kristendomen. Därmed misslyckades flera avverken att uppnå kriterierna för begreppen allsidighet och saklighet.
16

Metabolic profile of myosin heavy chain-based fiber types in the rat soleus after spinal cord transection

Otis, Jeffrey Scott 14 November 2000 (has links)
Fully differentiated muscle fibers can undergo considerable phenotypic changes in order to adjust to changing conditions of the physiological environment. It is generally accepted that the electrical impulses a muscle receives play a role in modulating the quantities of metabolic proteins (glycolytic and oxidative enzymes) and types of contractile proteins (myosin heavy chain, MHC) that are expressed. Research has shown that decreased neuromuscular activation following spinal cord transection (ST) results in adaptations in the physiological characteristics of paralyzed muscles, including atrophy and an accompanying loss of force production, and transformations of contractile and metabolic proteins toward a more fatigable state. However, it remains unclear whether or not a strong interdependence of energy metabolism and MHC isoform composition persists. Therefore, the goal of this study was to identify and quantify relative myosin heavy chain (MHC) isoform expression and metabolic enzyme profile adaptations at multiple time points (1, 3 and 6 months) in soleus fibers of rats following spinal cord transection (ST). To accomplish this, female Sprague-Dawley rats (~150 g, n = 15) were subjected to complete transection of the spinal cord at a mid-thoracic level. Age and weight-matched, non-operated rats served as controls (n = 15). The soleus was processed for quantitative single fiber histochemical analyses for succinate dehydrogenase (SDH, oxidative marker) and a-glycerophosphate dehydrogenase (GPD, glycolytic marker) activities (~30 fibers/muscle) and immunohistochemical analysis for MHC isoform composition. The total number of soleus fibers analyzed was ~900. Oxidative capacity was increased in muscle fibers at all time points after ST. Specifically, SDH activity was significantly higher than controls by 142, 127 and 206% at 1, 3 and 6 months post-ST, respectively. ISDH, a measure of total oxidative power, also increased in muscle fibers at all time points after ST. For example, 6 months after ST ISDH activity was 93% higher than controls (91.8-3.8 vs. 47.6-0.9 OD x 10-3, respectively). Glycolytic capacity peaked one month after ST. Thereafter, glycolytic capacity of all fibers steadily declined. For example, by 6 months, GPD activity had declined by 76% compared to 1 month GPD activities (3.3-0.2 vs. 13.7-1.4 OD x 10-3, respectively). These data suggest that the increases in glycolytic capacity are transient as fibers transition toward a faster MHC phenotype and then return towards control levels as fibers of a given type become phenotypically stable. The GPD/SDH ratio, an index of metabolic substrate utilization, peaked at one month after ST (394-41) and significantly decreased at 3 months (224-10) and at 6 months (95-7) after ST. Therefore, a shift occurred such that a greater dependence on oxidative metabolism was apparent. These data suggest that the oxidative capacities of soleus muscle fibers are not compromised after ST. In fact, as the fibers transitioned toward faster MHC isoforms, the GPD/SDH ratio was maintained or decreased, suggesting a reliance on oxidative metabolism regardless of MHC isoform composition. This might imply a dissociation between the contractile and metabolic characteristics of paralyzed soleus muscle fibers. However, these data are consistent with previous data and suggest that the increased fatigability observed after chronic reductions in neuromuscular activity are not due to compromised capacities for ATP synthesis. / Master of Science
17

PROPRIÉTÉS ÉLECTRONIQUES DU GRAPHITE

Schneider, Johannes M. 26 October 2010 (has links) (PDF)
Dans cette thèse le magnétotransport à basse température (T = 10 mK) et l'effet de Haas-van Alphen sont examinés pour le graphite naturel et le graphite HOPG. Dans la première partie, le magnétotransport au champ magnétique jusqu'à B = 11 T est présenté. Une analyse de Fourier du signal après soustraction du fond de magnétorésistance montre que le transport électrique dans le graphite est dominé par deux types de porteurs avec des fréquences et phases en accord avec le modèle SWM. Nous confirmons la validité du modèle SWM par des calculs détaillés de la structure de bande en champ magnétique. Le mouvement de l'énergie de Fermi pour B > 2 T est calculé d'une manière auto-cohérente en supposant que la somme des concentrations des électrons et des trous est constante. Des mesures sous champs magnétiques intenses (0 < B < 28 T) sont employées pour étudier l'effet Zeeman et la phase de l'onde de densité de charge. En ce qui concerne l'effet Zeeman, les calculs SWM incluant le mouvement de l'énergie de Fermi nécessitent un facteur de Lande g = 2.5 pour reproduire la séparation de spin des motifs dans les données. Les mesures de l'onde de charge de densité confirment que le champ magnétique auquel l'onde de charge de densité apparait est lie a la température par une formule de type Bardeen-Cooper-Schrieffer (BCS). Des mesures de l'effet de Haas-van Alphen confirment les résultats obtenus par de magnétotransport à bas champ.
18

PROPRIÉTÉS ÉLECTRONIQUES DU GRAPHITE

Schneider, Johannes M. 26 October 2010 (has links) (PDF)
Dans cette thèse le magnétotransport à basse température (T = 10 mK) et l'effet de Haas-van Alphen sont examinés pour le graphite naturel et le graphite HOPG. Dans la première partie, le magnétotransport au champ magnétique jusqu'à B = 11 T est présenté. Une analyse de Fourier du signal après soustraction du fond de magnétorésistance montre que le transport électrique dans le graphite est dominé par deux types de porteurs avec des fréquences et phases en accord avec le modèle SWM. Nous confirmons la validité du modèle SWM par des calculs détaillés de la structure de bande en champ magnétique. Le mouvement de l'énergie de Fermi pour B > 2 T est calculé d'une manière auto-cohérente en supposant que la somme des concentrations des électrons et des trous est constante. Des mesures sous champs magnétiques intenses (0 < B < 28 T) sont employées pour étudier l'effet Zeeman et la phase de l'onde de densité de charge. En ce qui concerne l'effet Zeeman, les calculs SWM incluant le mouvement de l'énergie de Fermi nécessitent un facteur de Lande g = 2.5 pour reproduire la séparation de spin des motifs dans les données. Les mesures de l'onde de charge de densité confirment que le champ magnétique auquel l'onde de charge de densité apparait est lie a la température par une formule de type Bardeen-Cooper-Schrieffer (BCS). Des mesures de l'effet de Haas-van Alphen confirment les résultats obtenus par de magnétotransport à bas champ.
19

Enginyeria de tràfic en xarxes de transport òptiques per a entorns d'àrea metropolitana (RPR) i de gran abast (ASON)

Spadaro, Salvatore 15 February 2005 (has links)
La arquitectura de las redes de transporte actuales está basada en la tecnología de transporte SDH (Synchronous Digital Hierarchy). Las redes SDH se han diseñado y están optimizadas básicamente para el transporte del tráfico de voz. Actualmente, se está experimentando un crecimiento exponencial del volumen de tráfico de datos. Este crecimiento se debe a que el protocolo IP se está consolidando como capa de integración para servicios múltiples, algunos de ellos con requerimientos de Calidad de Servicio (QoS) y también a la introducción de tecnología de acceso de alta velocidad. Las características estadísticas del tráfico de datos son diferentes respecto a las del tráfico telefónico. De hecho, el tráfico IP se caracteriza no solo por su asimetría sino por su naturaleza dinámica, ya que presenta fluctuaciones o picos difíciles de predecir a priori.Como consecuencia, ha surgido la necesidad de emigrar desde las actuales redes hacia una estructura más flexible y dinámica, optimizada para el transporte de tráfico de datos.La evolución de las actuales redes de transporte incluye trasladar todas las funcionalidades de SDH (conmutación, monitorización de la calidad de la señal, protección frente a fallos) a nivel óptico. El resultado consistirá en una red de transporte óptica (Optical Transport Network, OTN) basada en tecnología DWDM, con Optical Cross Connects (OXC) para encaminar canales ópticos de forma permanente o conmutada (Automatic Switched Optical Network, ASON).Uno de los principales problemas a solucionar por las operadoras de red es la eficiente gestión de la capacidad disponible, y así evitar por un lado la necesidad de sobredimensionar la red de transporte y por el otro optimizar la utilización de los recursos mediante la definición de estrategias de ingeniería de tráfico.La introducción de las redes de transporte a conmutación automática (ASON), capaces de proporcionar conexiones ópticas bajo demanda, es considerada como la solución de red que puede proporcionar el rápido y flexible aprovisionamiento de ancho de banda. Tal funcionalidad, posible gracias a la definición de un plano de control basado en el paradigma GMPLS, puede ser usada para gestionar de manera dinámica los recursos disponibles, tanto a nivel SDH como a nivel óptico, respondiendo de forma eficiente a las fluctuaciones del tráfico generado por la red cliente. Sin embargo, el problema que surge es el diseño de un mecanismo para disparar automáticamente las peticiones de establecimiento de circuitos SDH/canales ópticos conmutados.En este sentido, la primera contribución de esta Tesis es el diseño de un mecanismo de disparo de peticiones de circuitos SDH/canales ópticos basado en la monitorización y predicción del tráfico de la red cliente (IP). Además, el mecanismo diseñado incluye la definición de políticas de ingeniería de tráfico para la optimización de la utilización del elevado ancho de banda proporcionado por las conexiones ópticas. Concretamente, el mecanismo diseñado se caracteriza por la interoperabilidad entre la capa cliente y la capa de transporte.La Tesis incluye también una contribución sobre el diseño de una metodología para el dimensionado de la redes ASON, basada en la caracterización del tráfico de llegadas de peticiones de establecimiento de conexiones, mediante su valor medio y el factor de peakedness.Por otro lado, la optimización de los recursos disponibles es muy crítica cuando se produce un fallo en la infraestructura de red debido a la necesidad de encontrar rutas alternativas para el tráfico afectado. Debido al gran volumen de tráfico a transportar, un fallo en la infraestructura de red puede tener graves consecuencias económicas. Por ejemplo, un corte de una única fibra óptica produce el fallo de todas las longitudes de onda que transporta; de esta manera la pérdida de cada longitud de onda operante a 2.5 Gbps o 10 Gbps puede resultar en el corte de un enorme número de conexiones en curso. Por lo tanto, a mayor capacidad, mayor es la importancia de la rapidez y rendimiento de los mecanismos de protección y recuperación.Las estrategias de protección frente a fallos deben ser simples, minimizar las pérdidas de tráfico y deben utilizar eficientemente los recursos disponibles.La recién estandardizada tecnología para redes de entornos metropolitanos, Resilient Packet Ring (RPR) se caracteriza por mecanismos de protección optimizados para minimizar el tiempo de recuperación en caso de fallos. Además, tales mecanismos no requieren la asignación a priori de recursos de red a utilizar solamente en caso de fallos.Por lo que respecta a los mecanismos de recuperación, se puede optar por una estrategia de recuperación en una sola capa (single layer recovery) o alternativamente por una estrategia de recuperación en múltiples capas (multi-layer recovery), donde en la recuperación intervienen diferentes capas de la estructura de red. El esquema de recuperación multi-capas más fácil de implementar es el consistente en ejecutar los mecanismos de protección/recuperación de los distintos niveles de manera paralela e independiente. Esta estrategia no es, sin embargo, la más eficiente. La interoperabilidad entre los mecanismos de protección de las diferentes capas permite reaccionar más rápidamente a los fallos que se pueden producir.La segunda contribución de esta Tesis es el diseño de una política de coordinación entre los mecanismos de protección proporcionados por RPR y los mecanismos de protección definidos por la capa óptica. Concretamente, la estrategia diseñada se basa en la interoperabilidad entre la capa RPR y la capa de transporte (OTN) para redes de entornos metropolitanos. La estrategia diseñada permite, además, la optimización de los recursos de red. / The main objective of the traffic engineering (TE) strategies is the efficient mapping of the actual traffic onto the available network resources. Legacy Time Division Multiplexing-based networking architecture was basically designed to transport symmetric voice traffic. However, the volume of data traffic is increasing at explosive rate and already dominates the voice traffic. This is due to a progressive migration of many applications and services over the Internet Protocol (IP) and also to a deeper and deeper introduction of high-speed access technologies. Also there is the convergence towards the IP of real-time applications (i.e. multimedia applications) which have very strict QoS requirements. The statistical characteristics of the data traffic are rather different from those of telephone traffic. Specifically, IP traffic is highly dynamic showing predictable and unpredictable traffic surges/peaks. Such surges are caused by unexpected events such as user' behaviours, weather conditions, accidents, fault, etc. This can cause significant fluctuations of the aggregated data traffic to be carried by the transport networks. The current SONET/SDH transport networks (but also the incoming Optical Transport Networks) tend to be static, which means that connections (SONET/SDH circuits and light paths) are provided manually through the Network Management System. The manual configuration is time consuming, which means that weeks or even months are needed to provide high bandwidth connections.The highly dynamic IP traffic pattern does not match with the static provisioning of capacity of the optical transport networks, leading to non-optimal utilization of the resources (i.e. network congestion or under-utilization of resources).Thus, the problem that arises for Network Operators is how to efficiently manage the network resources in the transport network to efficiently respond to the changes in the traffic demands reaching, in such a way, traffic engineering objectives. The introduction of the Automatic Switched Optical Networks (ASON), which is able to provide dynamically switched connections on demand, is recognized as the enabling solution to meet the requirement of fast and flexible end-to-end bandwidth provisioning. The automatic set up and tear down of optical connections can be used for the dynamic management of the transport network resources to track significant variations in the volume of the network client traffic. In such a context, a mechanism that triggers demands to set up/tear down light paths as a function of the variation of the client traffic to be transported is required. The design of a multi-layer traffic engineering (MTE) strategy for IP/MPLS over ASON/GMPLS networks to face with the dynamic traffic demands is the first contribution of this Ph.D. Thesis. It has to be underlined that the policies for the set up of the light paths are out of the scope of this work. In fact, it is assumed that the set up/tear down of the switched connections is in charge of the ASON control plane, namely the GMPLS-based routing and signalling protocols.As a second contribution, it is presented a practical approach for ASON networks dimensioning purposes based on the approximate characterization of the traffic arrival process, through its mean and the peakedness factor. On the other hand, the optimization of the utilization of network resources is very critical when failures occur in the network as a consequence of the need of rerouting the affected traffic. The increase of the capacity and number of wavelengths that can be multiplexed onto the same fibre, each one carrying 2.5 or 10 Gbps client signals, implies that outages of the network infrastructure can have serious economical and social consequences. Network recovery/resilience, i.e., the capability of the networks to efficiently recover from failures, has become of vital importance. Thus, optical transport networks need to be very robust to face failures. The protection mechanisms should be designed basically with the aim to be simple, to minimize the traffic losses and to optimize the utilization of the network resources.Survivability strategies in current transport networks are based on the pre-allocation of network resources to be used only to switch (route) the affected traffic in case of failures. In legacy multi-layer networks, each layer (e.g. IP, SDH) has its own protection mechanism built in, independent from the other layers. Network recovery basically relies on the SONET/SDH network layer. Indeed, different mechanisms, based on the protection approach, have been proposed that allow fast recovery within the target of 50 ms. Nevertheless, SONET/SDH protection is mainly limited to ring topologies and it is not able to distinguish between different priorities of traffic and it has not vision of higher layer failures.The emerging packet-based Resilient Packet Ring (RPR) technology for metropolitan networks provides powerful protection mechanisms that minimize the time needed to restore the traffic without the pre-allocation of resources.To face to failures, the resilience single-layer strategy (a single layer has the responsibility for the recovery) is very simple from the implementation point of view. However it may not be able to efficiently recover the network from all kind of failures that can occur. Therefore, multi-layer resilience (various network layers can participate to the recovery actions) provides better performance not only in terms of protection but also in terms of resources optimization. Multi-layer resilience strategies require coordinating the recovery mechanisms provided by each layer. In such a context, another contribution of this Ph.D. Thesis is the design and evaluation of a multi-layer resilience mechanism to be used in the IP over RPR over intelligent optical transport network for metropolitan environment to efficiently face with a wide range of network outages, while optimizing the utilization of the network resources. Its novelty relies on the interworking required between the RPR and the optical transport layer. Finally, the fourth contribution of the Thesis deals with the optimization of the bandwidth utlization of the RPR rings taking benefits from the automatic switching of optical connections capabilities of the underlying ASON/GMPLS networks.
20

Effects Of Acrylamide And Resveratrol On Rabbit Liver And Kidney Antioxidant Enzymes

Kalin, Cigdem 01 January 2010 (has links) (PDF)
Resveratrol is one of the promising naturally occurring polyphenolic compound found in red wine having antioxidant and anti-carcinogenic properties. However, in vivo studies investigating the effects of resveratrol on antioxidant enzymes are limited. In the present study, we investigated, for the first time, the influence of resveratrol on liver and kidney antioxidant enzymes and oxidative stress markers in acrylamide treated and control rabbits. New Zealand male rabbits were treated with acrylamide and resveratrol, separately in two different doses and conditions. Their combined effects were also investigated. While, acrylamide treatment significantly decreased the glutathione peroxidase (GPx) activity in liver (1.24-fold), it was significantly increased (1.20 &ndash / 1.40-fold) by combined effect of resveratrol and acrylamide in liver and kidney. Furthermore, alone resveratrol administration increased (~1.37 &ndash / fold) GPx activity in kidney. Although, glutathione reductase (GR) was found to be significantly increased (~1.30-fold) in two different dose of resveratrol treated rabbit liver, it was not changed in acrylamide and their combined treatments. Despite, glutathione (GSH) content was decreased around 1.6 fold as a result of acrylamide treatment in rabbit liver and kidney cytosols, GSH level was returned to normal levels by resveratrol tretment in rabbit liver and kidney. Furthermore, acrylamide treatment significantly increased the SDH activity in blood serum (1.68-fold) and in liver (1.27-fold) with respect to control. On the other hand, resveratrol treatment brought this activity nearly normal level in acrylamide treated rabbits.. Besides, sorbitol deydrogenase (SDH) was found to be decreased (3.13-fold) significantly in rabbit liver cytosol as a result of single dose of 100 mg/kg b.w. resveratrol treatment. Moreover, catalase activity and MDA level were not affected from either resveratrol or acrylamide and with their combination effect in investigated rabbit organs. An important liver damage marker enzyme other than ALT and AST, SDH was characterized in terms of substrate, cofactor and enzyme concentration in rabbits which have been not investigated before and found to be 200 mM, 141 &micro / M and 0.5 &micro / L, respectively in rabbit liver. Furthermore, the Km value was first calculated in liver of New Zealand rabbits as 55,5 mM. In addition to these, in vitro effects of resveratrol on GST activity was also studied throughout this study. Resveratrol was shown to be a noncompetitive inhibitor for liver cytosolic GST against substrate CDNB with Ki of 175 &micro / M. On the other hand, resveratrol was shown to be a competitive inhibitor for liver cytosolic GST against substrate GSH with Ki of 55 &micro / M. The results of the present study have demonstrated for the first time that resveratrol induced some of the antioxidant enzyme activities and as well nonenzymatic antioxidants in rabbit liver and kidney. The results of GPx, GR, SDH activities and GSH level have also suggested that resveratrol may have protective effects on acrylamide induced hepatoxicity and renal toxicity. Therefore, it may be a therapeutic approach for the oxidative stress-related diseases such as cancer. However, further in vivo studies are required to clarify the effect of resveratrol on both acrylamide-induced toxicity and bioavailability in the body.

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