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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.
31

Mecanismos de Modulación de Receptores Nicotínicos por Anestésicos Locales con Grupos Amino

Cobo Velacoracho, Raúl 09 September 2019 (has links)
La tetracaína (Ttc), cuyas moléculas en solución fisiológica se encuentran mayoritariamente (97 %) en forma protonada, bloquea la corriente (IACh) evocada por acetilcolina (ACh) en ovocitos a los que se ha microtrasplantado receptores nicotínicos de acetilcolina (nAChRs) de la electroplaca de Torpedo marmorata. El bloqueo del nAChRm por Ttc fue muy potente, en el rango submicromolar (IC50= 0.5 μM) y reversible, recuperándose las respuestas a valores control tras un periodo de varios minutos. A concentraciones tan bajas como 0.1 μM, la Ttc ejerció un bloqueo que fue dependiente de voltaje, indicando que ejerce un bloqueo a canal abierto. El sitio de unión se pudo determinar en el interior del canal mediante técnicas de acoplamiento molecular. A concentraciones mayores (0.7 μM) se pudo observar un mecanismo de bloqueo distinto, a canal cerrado, que es independiente de voltaje y que se puede explicar por la unión de la Ttc a lugares situados en el ECD del nAChRm, que fueron determinados en los experimentos de docking virtual. Además, a esta concentración la Ttc aceleró la cinética de desensibilización de la IACh, cuando las células se mantuvieron en presencia sostenida del agonista. Esta se evocó cuando se co-aplicó la Ttc junto a la ACh a potenciales negativos. Por el contrario, cuando solamente se pre-aplicó la Ttc (aplicación previa a la de ACh), o cuando se co-aplicó a potenciales positivos, no se modificó la cinética de desensibilización, a pesar de que sí hubo una cierta inhibición de la IACh. Estos experimentos permitieron determinar que el sitio de unión de la Ttc que acelera la desensibilización se encuentra en el interior del canal. El ensayo de docking permitió localizar los residuos a los que su une la Ttc dentro del canal a altas concentraciones (con menor afinidad), que es más superficial que el implicado en el bloqueo a canal abierto. El lugar de unión determinado por anclaje virtual incluye la interacción de Ttc con αE262, γN224, γK271, y γE274, residuos que han sido previamente involucrados en el proceso de activación y desensibilización (Bouzat y cols., 2008; Forman y cols., 2007). El otro anestésico local (LA) estudiado, la benzocaína (Bzc), no posee carga al pH al que se efectúan los registros electrofisiológicos. La Bzc, al igual que la Ttc, inhibió la IACh, pero con una potencia menor, en el rango submilimolar y, a diferencia de la Ttc, su bloqueo fue independiente de voltaje. A pesar de mediar un bloqueo independiente de voltaje, la Bzc, evoca una corriente de rebote (IRb), similar a la que median moléculas que ejercen un bloqueo de canal abierto, sugiriendo que la Bzc podría estar uniéndose en el interior del canal. Otro efecto destacado de la Bzc sobre el nAChRms fue la aceleración de la desensibilización, haciéndola marcadamente más rápida incluso a potenciales positivos (a diferencia del efecto mediado por la Ttc). Además, se observó que, tras su pre-aplicación, la cinética de activación de la IACh se enlenteció y hubo un bloqueo de nAChRs, a canal cerrado, cuya recuperación fue especialmente lenta. Los efectos de ambos LAs fueron muy diferentes sobre los GABAAR. Así, la Ttc apenas tuvo efectos sobre este receptor, incluso a una concentración 10 veces superior a la IC50 determinada para el nAChRm. Por el contrario, la Bzc, aplicada a concentraciones similares a las que inhiben la IACh, aumentó la desensibilización y evocó una IRb similar a la observada en los nAChRs. Adicionalmente, la Bzc tuvo efectos sobre otros canales, como el ClC-0 y el CaCC. En relación con la Bzc, es interesante destacar que debido a su estructura química tiene una muy baja solubilidad al agua y, por tanto, debe solubilizarse en solventes como el etanol (EtOH) o el DMSO. Debido a que estos solventes pueden no ser totalmente inertes se probaron, en las mismas condiciones experimentales. No observándose efectos sobre los nAChRms.
32

Estudio de la biología trófica de cinco especies de peces bentónicos de la costa de Cullera. Relaciones con la acumulación de metales pesados

Jaramillo Londoño, Ángela María 24 May 2010 (has links)
Los estudios acerca de la ecología trófica de los peces, en los cuales se relacionan la biología y fisiología de las especies con su hábitat, régimen alimentario, tipo de dieta y relaciones bióticas, aportan información básica y necesaria para comprender el papel ecológico que desempeñan estos organismos dentro del ecosistema que habitan, y por lo tanto para establecer protocolos de gestión de sus poblaciones. Esta tesis aporta un mayor conocimiento de la biología, fenología y hábitos alimenticios de cinco especies de peces bentónicos de interés comercial en el litoral valenciano y de los cuales la información es escasa, como son el salmonete de roca (Mullus surmuletus), el lenguado tigre (Synaptura lusitanica), la escorpa (Scorpaena scrofa), la rata (Uranoscopus scaber) y el torpedo común o vaca (Torpedo torpedo). Así mismo, relacionar la importancia que tienen los aspectos de tipo ecológico y fisiológico de los peces con la incorporación de sustancias contaminantes como metales pesados (Cd, Pb, Cu y Zn) y conocer sus patrones de acumulación en diferentes órganos y tejidos. Los resultados indican que estas especies son pescadas en toda la bahía, de forma artesanal y con trasmallo, a profundidades que oscilan entre los 6m y los 20m y a lo largo de todo el año. Su distribución y abundancia se ve condicionada principalmente por factores como la estacionalidad y algunas especies como S. scrofa y T. torpedo presentan una segregación por sexos en su patrón de distribución. . La mayoría de las especies tienen su período de maduración sexual y desove en los meses de primavera y comienzo del verano. Estas épocas coinciden con períodos de reclutamiento de juveniles, siendo además favorables en cuanto a la acumulación de reservas energéticas corporales. Las preferencias dietarias que hemos encontrado en las especies estudiadas fueron variadas, de tal manera que M. surmuletus se alimenta de presas pequeñas pero abundantes, predominando los crustáceos. / Jaramillo Londoño, ÁM. (2009). Estudio de la biología trófica de cinco especies de peces bentónicos de la costa de Cullera. Relaciones con la acumulación de metales pesados [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8320 / Palancia
33

La pensée navale et le débat sur la torpille en Angleterre au cours de la décennie 1880

Gabriel, Sauvé 08 1900 (has links)
L’évolution du débat sur la pensée navale en Angleterre de la décennie 1880, suivant la fin d’une période d’intenses changements technologiques dans les marines de guerre est marquée par le déclin d’un mode de réflexion matériel et l’ascension, à partir des années 1885 et 1886, de l’école historique de John Knox Laughton. Selon la méthode matérielle, populaire au cours de la période de transformation technique, la guerre sur mer est entièrement tributaire du Progrès, tandis que, pour les tenants de la méthode historique, des principes et des leçons immuables la régissent. À travers l’évolution de ce débat, on constate l’introduction, par la Jeune École française, d’une perspective matérialiste et de la stratégie navale comme objet de réflexion, et son exploitation par l’école historique anglaise. L’émergence de la stratégie comme sujet de débat coïncide donc avec le triomphe de l’école historique. Croyant que la torpille allait démocratiser la puissance navale en empêchant le belligérant le plus puissant d’user de sa maîtrise des mers, la Jeune École connut un succès fulgurant qui déborda des côtes françaises et atteint l’Angleterre. Néanmoins, les matérialistes anglais, demeurant beaucoup plus modérés que les français, furent finalement marginalisés par une école historique utilisant les exagérations de la Jeune École, dont les insuffisances sont apparues lors des manœuvres de l’été 1886, pour disqualifier entièrement la méthode matérielle. Étudiant les débats du Royal United Service Institution Journal, ce mémoire démontre l’existence, en Angleterre, au cours de la décennie 1880, d’un débat polarisé au contraire d’une historiographie ne montrant que l’ascension des précurseurs de Mahan et de l’école historique. / Great Britain saw in the 1880s, at the end of a period of intense technical change and before the publication of Mahan’s classic on Sea Power, the decline of the material way of thinking about naval affairs and the rise, from the years 1885 and 1886, of the historical school of John Knox Laughton. Proponents of a material method established the idea that technological change altered naval warfare in a fundamentally way. They were, however, opposed by the partisans of a historical method who supported the idea that naval warfare is set on some timeless principles which can be discovered by the use of the methods of the new historical profession. Throughout the decade, the material method, successful in an era of rapid technological change, quickly subsumed to Mahan’s precursors. In a debate originally dominated by tactics, we observe the introduction of strategy by the French materialist Jeune École. Consequently, strategy became the core of the historical school and seems closely linked to the rise of strategy as a subject of reflection. The Jeune École believed that the torpedo would democratize Sea Power in making the powerful navies to use its mastery over the oceans. The Jeune École’s original success was so great, in France and abroad, that it influenced the English’s debate. Although materialists in Great Britain where more moderate than in France, they finally got marginalize by the historical school using the Jeune École’s wildest claims to disqualify the materialist point of view. Studying the debates through the Royal United Service Institution Journal, this thesis shows the existence, in Great Britain, of a debate centered on two method of thinking naval warfare and contributes to reassess current historiography which still focuses solely on the rise of Mahan’s precursors.
34

La pensée navale et le débat sur la torpille en Angleterre au cours de la décennie 1880

Gabriel, Sauvé 08 1900 (has links)
L’évolution du débat sur la pensée navale en Angleterre de la décennie 1880, suivant la fin d’une période d’intenses changements technologiques dans les marines de guerre est marquée par le déclin d’un mode de réflexion matériel et l’ascension, à partir des années 1885 et 1886, de l’école historique de John Knox Laughton. Selon la méthode matérielle, populaire au cours de la période de transformation technique, la guerre sur mer est entièrement tributaire du Progrès, tandis que, pour les tenants de la méthode historique, des principes et des leçons immuables la régissent. À travers l’évolution de ce débat, on constate l’introduction, par la Jeune École française, d’une perspective matérialiste et de la stratégie navale comme objet de réflexion, et son exploitation par l’école historique anglaise. L’émergence de la stratégie comme sujet de débat coïncide donc avec le triomphe de l’école historique. Croyant que la torpille allait démocratiser la puissance navale en empêchant le belligérant le plus puissant d’user de sa maîtrise des mers, la Jeune École connut un succès fulgurant qui déborda des côtes françaises et atteint l’Angleterre. Néanmoins, les matérialistes anglais, demeurant beaucoup plus modérés que les français, furent finalement marginalisés par une école historique utilisant les exagérations de la Jeune École, dont les insuffisances sont apparues lors des manœuvres de l’été 1886, pour disqualifier entièrement la méthode matérielle. Étudiant les débats du Royal United Service Institution Journal, ce mémoire démontre l’existence, en Angleterre, au cours de la décennie 1880, d’un débat polarisé au contraire d’une historiographie ne montrant que l’ascension des précurseurs de Mahan et de l’école historique. / Great Britain saw in the 1880s, at the end of a period of intense technical change and before the publication of Mahan’s classic on Sea Power, the decline of the material way of thinking about naval affairs and the rise, from the years 1885 and 1886, of the historical school of John Knox Laughton. Proponents of a material method established the idea that technological change altered naval warfare in a fundamentally way. They were, however, opposed by the partisans of a historical method who supported the idea that naval warfare is set on some timeless principles which can be discovered by the use of the methods of the new historical profession. Throughout the decade, the material method, successful in an era of rapid technological change, quickly subsumed to Mahan’s precursors. In a debate originally dominated by tactics, we observe the introduction of strategy by the French materialist Jeune École. Consequently, strategy became the core of the historical school and seems closely linked to the rise of strategy as a subject of reflection. The Jeune École believed that the torpedo would democratize Sea Power in making the powerful navies to use its mastery over the oceans. The Jeune École’s original success was so great, in France and abroad, that it influenced the English’s debate. Although materialists in Great Britain where more moderate than in France, they finally got marginalize by the historical school using the Jeune École’s wildest claims to disqualify the materialist point of view. Studying the debates through the Royal United Service Institution Journal, this thesis shows the existence, in Great Britain, of a debate centered on two method of thinking naval warfare and contributes to reassess current historiography which still focuses solely on the rise of Mahan’s precursors.
35

The eagle and the albatross : Australian aerial maritime operations 1921-1971

Wilson, David Joseph, Humanities & Social Sciences, Australian Defence Force Academy, UNSW January 2003 (has links)
The aim of this thesis is to examine the relationship between the Royal Australian Air Force (RAAF) and the Royal Australian Navy (RAN) regarding the operation of aircraft from ships of the RAN and from RAAF shore bases. The effects of the separate intellectual development of maritime doctrine in the RAAF and RAN, and the efforts of the two Australian services to transfer theory into practice will be considered in the pre- (and post) World War II period, with due consideration of the experience of the services in both wars. The thesis will also discuss the problems that were faced by the RAAF and RAN to develop mutually acceptable operational procedures to enable the efficient use of aircraft in a maritime setting. The influence and effect on RAAF and RAN doctrine and equipment procurement, as a result of the special relationships that developed between the Air Force and Navy of Australia and Britain will be critically examined. A similar approach to the post war US/Australian relationship, and its effect on the Australian services, will also be critically examined. The thesis being propounded is that the development of a unique Australian maritime policy was retarded due to a combination of the relationship with Britain and the United States, lack of suitable equipment, lack of clear operational concepts in both the RAAF and RAN and the parochial attitude of the most senior commanders of both Services. The study has been based on Department of Navy, Department of Air and Department of Defence documents held in the National Archives of Australia in Canberra and Melbourne. In addition, relevant documents from the Admiralty and Air Ministry related to the development of naval aviation on RAN vessels during World War I, the attitude of the RAF toward the deployment of RAAF units to Singapore, and the negotiations that resulted in the procurement of HMA Ships Sydney and Melbourne, have been perused. Wartime operational records of the RAAF have been examined to obtain data to enable a critical study to be made of the RAAF anti-submarine campaign, torpedo bomber operations and the maritime campaign undertaken from bases in North Western Area during World War II. The influence of the commander of the United States 5th Air Force has also been incorporated in the discussion. The research uncovered procedural and operational variations between the two Services, the diversion of key elements from Australian command and the priority given to the American line of advance that resulted in Australian operations being given a secondary, supportive, status. A conclusion reached as a result of this research has been that the development of a unique Australian maritime aerial capability was restricted by the requirement of Britain to deploy flying units to Singapore in 1940. Similarly, the pressure exerted on the RAN by the Admiralty to purchase the Light Fleet Carriers in the late 1940s was more in the interests of the RN and British foreign policy than that of the RAN. Overall, the relationship with the Britain and the United States masked the real weakness in Australia???s maritime operations and retarded its development.
36

The eagle and the albatross : Australian aerial maritime operations 1921-1971

Wilson, David Joseph, Humanities & Social Sciences, Australian Defence Force Academy, UNSW January 2003 (has links)
The aim of this thesis is to examine the relationship between the Royal Australian Air Force (RAAF) and the Royal Australian Navy (RAN) regarding the operation of aircraft from ships of the RAN and from RAAF shore bases. The effects of the separate intellectual development of maritime doctrine in the RAAF and RAN, and the efforts of the two Australian services to transfer theory into practice will be considered in the pre- (and post) World War II period, with due consideration of the experience of the services in both wars. The thesis will also discuss the problems that were faced by the RAAF and RAN to develop mutually acceptable operational procedures to enable the efficient use of aircraft in a maritime setting. The influence and effect on RAAF and RAN doctrine and equipment procurement, as a result of the special relationships that developed between the Air Force and Navy of Australia and Britain will be critically examined. A similar approach to the post war US/Australian relationship, and its effect on the Australian services, will also be critically examined. The thesis being propounded is that the development of a unique Australian maritime policy was retarded due to a combination of the relationship with Britain and the United States, lack of suitable equipment, lack of clear operational concepts in both the RAAF and RAN and the parochial attitude of the most senior commanders of both Services. The study has been based on Department of Navy, Department of Air and Department of Defence documents held in the National Archives of Australia in Canberra and Melbourne. In addition, relevant documents from the Admiralty and Air Ministry related to the development of naval aviation on RAN vessels during World War I, the attitude of the RAF toward the deployment of RAAF units to Singapore, and the negotiations that resulted in the procurement of HMA Ships Sydney and Melbourne, have been perused. Wartime operational records of the RAAF have been examined to obtain data to enable a critical study to be made of the RAAF anti-submarine campaign, torpedo bomber operations and the maritime campaign undertaken from bases in North Western Area during World War II. The influence of the commander of the United States 5th Air Force has also been incorporated in the discussion. The research uncovered procedural and operational variations between the two Services, the diversion of key elements from Australian command and the priority given to the American line of advance that resulted in Australian operations being given a secondary, supportive, status. A conclusion reached as a result of this research has been that the development of a unique Australian maritime aerial capability was restricted by the requirement of Britain to deploy flying units to Singapore in 1940. Similarly, the pressure exerted on the RAN by the Admiralty to purchase the Light Fleet Carriers in the late 1940s was more in the interests of the RN and British foreign policy than that of the RAN. Overall, the relationship with the Britain and the United States masked the real weakness in Australia???s maritime operations and retarded its development.

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