Spelling suggestions: "subject:"4he eco"" "subject:"ehe eco""
281 |
La dimension réelle du père dans le passage à l'acte dans un contexte de décompensation psychotique et son rapport à la pulsion invocante / The dimension of the Real of the father in the passage to the act, in a context of psychotic decompensation and its relation to the invocative drive / La dimension réal del padre en el pasage al acto, en un momento de descompensación psicotica y su relacion con la pulsión invocanteMedina Tamayo, Olga Lucia 09 December 2017 (has links)
La pulsion invocante traverse l’oeuvre de Jacques Lacan, bien qu’il n’ait jamais vraiment développé ce thème : son objet est la voix, au moment même où cette dernière fait défaut : notre hypothèse est que le sujet passe à l’acte au moment où la voix se tait, il n’y a pas de cogito. Intriquée à la pulsion scopique, la pulsion invocante a pour signature le silence. Le passage à l’acte procède d’un « je ne pense pas », du langage et non des affects que le sujet subirait. Cette thèse envisage la dimension réelle du père dans le passage à l’acte, en cas de décompensation psychotique, dans son rapport à la pulsion invocante. Des lois ont été établies pour différencier les actes des sujets désignés fous, psychotiques, de ceux des autres pauvres, faibles et criminels, ce qui précise le cadre de l’expertise mentale qui n’est pas étranger à notre recherche. Les textes des lois de 1838 et de 1990 ont été modifiés non tant pour assurer une meilleure protection des patients que pour des raisons sécuritaires. Ainsi, les différents modes d’hospitalisation ont été révisés : hospitalisation libre, hospitalisation à la demande d’un tiers (HDT), hospitalisation d’office (HO) … jusqu’à la notion récente de soins sous contrainte. Notre thèse commence par revisiter ces aspects historiques pour situer le contexte des passages à l’acte qui seront ensuite analysés à la lumière de l’enseignement de Lacan. Nous envisageons la voix comme une tentative de substitution à la forclusion duNom du Père, la voix venant suppléer et compléter le silence de l’Autre. Pour ce faire, nous développons plusieurs illustrations cliniques. Dans le cas de Juan, nous montrons comment le travail thérapeutique lui a permis de ne pas entrer dans le silence et de rechercher son nom en s’adressant à nous. Le travail de la parole empêche le passage à l’acte. Le roman de Duras, La pluie d’été, permet d’entendre la pulsion invocante comme l’écho de la voix de l’Autre et sa résonance corporelle. Avec Seth, la voix du père et celle du diable se confondent, pacte d’alliance entre les pères terribles interdicteurs et les figures féminines. Avec Mme X, nous approchons mieux les aspects de la formule de Lacan : dans la psychose, la voix sonorise le regard. Nous pouvons ensuite prendre la mesure de ce qui se passe pour Chris qui ne supporte pas la voix. La question de l’envers de l’auto-punition est abordée avec la patiente Médée. Nous prenons alors appui sur Gabriel Garcia Marquez avec chronique d’une tentative mortifère annoncée. Nous tentons enfin de comprendre le déclenchement de la psychose chez Telfusa, que les voix selon ses dires accompagnent constamment, même quand elle parle. Le traitement se présentera ainsi : non à Juana la folle mais oui à la liberté. Cette thèse tente de mettre en évidence la valeur propre à la parole introduite par la psychanalyse en éclairant la clinique de l’acte dans le champ des psychoses. / The invocative drive goes through the work of Jacques Lacan, although he never really developed this theme: its object is the voice, at the very moment when it is lacking: our hypothesis is that the subject passes to the act when the voice is silenced, there is no cogito. Intricate to the scopic drive, the invocative drive has the silence as a signature. The passage to the act proceeds from a "I do not think", from language and not from affects that the subject would suffer. This thesis considers the dimension of real of the father in the passage to the act, in a psychotic decompensation case, in his relation to the invocative drive. Laws have been established to differentiate the actions of the designated as crazy, psychotic subjects from those of the poor, weak and criminals, which specifies the framework of mental expertise that is not foreign to our research. The texts of the laws of 1838 and 1990 were modified not so much to ensure a better protection of the patients as for security reasons. Thus, the various modes of hospitalization were revised: free hospitalization, hospitalization at the request of a third party, duty of hospitalization ... until the recent concept of duty of care. Our thesis begins by revisiting these historical aspects to situate the context of passage to the act which will then be analyzed in the light of Lacan's teaching. We envision the voice as a tentative to substitute for the foreclosure of the Name of the Father, the voice supplies and completes the silence of the Other. To do this, we develop several clinical illustrations. In the case of Juan, we show how the therapeutic work allowed him not to go into silence and look for his name by addressing to us. The work of speech prevents the passage to the act. Duras' novel, Summer Rain, allows us to hear the invocative drive as the echo of the voice of the Other and its bodily resonance. With Seth, the voice of the father and the devil are confused, a pact of alliance between the terrible interdicting fathers and the female figures. With Mrs. X, we are getting closer to the aspects of Lacan's formula: in psychosis, the gaze sounds. We can then take inconsideration what happened to Chris who cannot stand the voice. The question of the reverse side of self-punishment is discussed with the patient Medea. We then rely on Gabriel Garcia Marquez with a chronic of a deadly attempt announced. Finally, we try to understand the outbreak of psychosis in Telfusa, whom the voices according to her constantly accompany her, even when she speaks. The treatment will be like this: no to Juana the Crazy but yes to freedom. This thesis attempts to highlight the proper value of the word introduced by psychoanalysis, by illuminating the clinical practice of the passage to the act in the field of psychosis. / La pulsion invocante atraviesa la obra de Jacques Lacan, aunque él nunca desarrolló realmente este tema: su objeto es la voz, en el momento mismo en que ella falta: nuestra hipótesis es que el sujeto pasa al acto cuando la voz se calla, no hay cogito. Intrincada a la pulsión escópica, la pulsión invocante tiene como firma, el silencio. El pasaje al acto procede de un "yo no ienso", del lenguaje, y no de un afecto del cual sufriría el sujeto. Esta tesis considera la dimensión real del padre en el pasaje al acto, en caso de descompensación psicótica, en su relación con la pulsión invocante. Se han establecido leyes para diferenciar los actos de los sujetos designados como locos, psicóticos de los actos de los pobres, débiles y criminales lo que especifica el marco de peritaje psicológico que no es ajeno a nuestra investigación. Los textos de las leyes de 1838 y 1990 se modificaron no tanto para garantizar una mejor protección de los pacientes como por razones de seguridad. Por lo tanto, se revisaron los diversos modos de hospitalización: hospitalización libre, hospitalización por pedido de un tercero (HDT), hospitalización de oficio (HO) ... hasta el concepto reciente de obligación de tratamiento. Nuestra tesis comienza revisando estos aspectos históricos para ubicar el contexto de los pasajes del acto, que luego será analizado a la luz de la enseñanza de Lacan. Vislumbramos la voz como un intento de sustitución a la forclución del Nombre del Padre, la voz que viene a suplir y completar el silencio del Otro. Para hacer esto, desarrollamos varias ilustraciones clínicas. En el caso de Juan, mostramos cómo el trabajo terapéutico le permitió no quedarse en el silencio y buscar su nombre dirigiéndose a nosotros. El trabajo de la palabra impide el paso al acto. La novela de Duras, lluvia de verano, nos permite entender la pulsión invocante como el eco de la voz del Otro y su resonancia corporal. Con Seth, la voz del padre y el diablo se confunden, un pacto de alianza entre los padres terribles que prohíben y las figuras femeninas. Con la Sra. X, nos estamos acercando a los aspectos de la fórmula de Lacan: en la psicosis, la voz sonoriza la mirada. Podemos enseguida tomar en consideración lo que le sucede a Chris que no soporta la voz. La cuestión del reverso del autocastigo la abordamos con la paciente Medea. Nos apoyamos en Gabriel García Márquez con crónica de un intento de muerte anunciado. Finalmente, intentamos de comprender el desencadenamiento de la psicosis en Telfusa, a quien las voces, según ella, la acompañan constantemente, incluso cuando habla. El tratamiento se presenta asi: no a Juana la loca, y si a la libertad. Esta tesis trata de poner en evidencia el valor propio de la palabra introducida por el psicoanálisis, esclareciendo la clínica del acto en el campo de las psicosis.
|
282 |
Processus atomiques cohérents appliqués à l'analyse spectrale très large bande de signaux radio fréquenceLavielle, Vincent 04 November 2004 (has links) (PDF)
Dans cette thèse, nous appliquons le phénomène de "hole burning" spectral (SHB), dans des matrices cristallines dopées par des ions terres rares, au traitement optique de l'information. Nous présentons la première démonstration expérimentale d'un analyseur spectral de signaux radio fréquence (RF) à très large bande instantanée, exploitant la sélectivité spectrale de ces matériaux photosensibles. L'utilisation de la technologie SHB, à basse température, permet d'atteindre des performances remarquables en terme de largeur de bande et de produit temps×bande passante. Le principe du spectromètre repose sur la séparation angulaire des composantes spectrales du signal RF préalablement transposé sur une porteuse optique. On grave un ensemble de réseaux de diffraction monochromatiques, multiplexés en longueur d'onde, dans un cristal dopé par des ions terres rares. Le faisceau lumineux, porteur du signal RF, est dirigé vers le cristal. Les différentes composantes spectrales sont alors diffractées et simultanément séparées angulairement à la sortie du cristal. Nous avons ainsi pu démontrer expérimentalement l'analyse spectrale de signaux RF sur une bande passante instantanée de 3,3 GHz avec une capacité de 100 canaux spectraux et une résolution ultime de 500 kHz. Ce dispositif possède une dynamique de 35 dB optique, limitée par la détection. Nous montrons la capacité de zoom spectral dans une région spécifique du domaine total couvert, avec augmentation de la résolution spectrale.
|
283 |
Les représentations de la propagation du son, d'Aristote à l'EncyclopédieBaskevitch, François 20 October 2008 (has links) (PDF)
Entre la théorie de la musique et l'étude de la perception, il y a peu d'espace, dans la science Scolastique, consacré à la physique des sons. La mécanique aristotélicienne ne prévoit pas le mouvement sans transport de matière et cette lacune constitue un blocage. A partir du début du XVIIème siècle, de nombreux savants traitent le sujet, parfois dans des ouvrages entiers, souvent en quelques lignes. Le phénomène est invisible et fugitif, alors on invente des représentations. Parmi elles, la célèbre métaphore des ronds dans l'eau rencontre un succès certain, mais également le flux de corpuscules ou les rayons sonores. La rédaction de l'Encyclopédie est contemporaine de la mathématisation de la propagation des ondes, avec la modélisation par les cordes vibrantes. A travers une Histoire de l'Acoustique Physique, on entreprend ici l'étude de ces représentations et des controverses qu'elles suscitent parmi les différents courants de la pensée scientifique, de l'Antiquité aux Lumières.
|
284 |
Parameter and State Estimation with Information-rich SignalsEvestedt, Magnus January 2007 (has links)
<p>The complexity of industrial systems and the mathematical models to describe them increases. In many cases, point sensors are no longer sufficient to provide controllers and monitoring instruments with the information necessary for operation. The need for other types of information, such as audio and video, has grown. These are examples of information-rich signals for which suitable applications range in a broad spectrum from micro-electromechanical systems and bio-medical engineering to paper making and steel production.</p><p>Recursive parameter estimation algorithms are employed to identify parameters in a mathematical model from measurements of input and output signals. For accurate parameter estimation, the input signal must be <i>persistently exciting, i.e.</i> such that important features of the modelled system are reflected in the output over a sufficient period of time.</p><p>The Stenlund-Gustafsson (SG) algorithm, a Kalman filter based method for recursive parameter estimation in linear regression models, that does not diverge under lack of excitation, is studied. The stationary properties of the algorithm and the corresponding Riccati equation are formulated in terms of the excitation space spanned by the regressor vectors.</p><p>Furthermore, it is shown that the Riccati equation of the studied algorithm can be solved element-wise. Convergence estimates for the elements of the solution to the Riccati equation are provided, directly relating convergence rate to the signal-to-noise ratio in the regression model. An element-wise form of the parameter update equation is also given, where the connection to specific elements of the solution to the Riccati equation is apparent.</p><p>The SG-algorithm is employed for two applications with audio signals. One is in an acoustic echo cancellation setting where its performance is shown to match that of other well-known estimation techniques, such as the normalized least mean squares and the Kalman filter. When the input is not sufficiently exciting, the studied method performs best of all considered schemes.</p><p>The other application is the Linz-Donawitz (LD) steel converter. The converter consists of a vessel with molten metal and foam is produced to facilitate chemical reactions. A common problem, usually referred to as slopping, arises when the foam rises above the limits of the vessel and overflows. A warning system is designed, based on the SG-algorithm and change detection methods, to give alarms before slopping occurs. A black-box model relates different sensor values of which one is the microphone signal picked up in the area above the converter. The system detected slopping correctly in 80% of the blows in field studies at SSAB Oxelösund.</p><p>A practical example of a vision-based system is provided by cavity form estimation in a water model of the steel bath. The water model is captured from the side by a video camera. The images together with a non-linear model are used to estimate important process parameters, related to the heat and mass transport in the LD-converter.</p>
|
285 |
Parameter and State Estimation with Information-rich SignalsEvestedt, Magnus January 2007 (has links)
The complexity of industrial systems and the mathematical models to describe them increases. In many cases, point sensors are no longer sufficient to provide controllers and monitoring instruments with the information necessary for operation. The need for other types of information, such as audio and video, has grown. These are examples of information-rich signals for which suitable applications range in a broad spectrum from micro-electromechanical systems and bio-medical engineering to paper making and steel production. Recursive parameter estimation algorithms are employed to identify parameters in a mathematical model from measurements of input and output signals. For accurate parameter estimation, the input signal must be persistently exciting, i.e. such that important features of the modelled system are reflected in the output over a sufficient period of time. The Stenlund-Gustafsson (SG) algorithm, a Kalman filter based method for recursive parameter estimation in linear regression models, that does not diverge under lack of excitation, is studied. The stationary properties of the algorithm and the corresponding Riccati equation are formulated in terms of the excitation space spanned by the regressor vectors. Furthermore, it is shown that the Riccati equation of the studied algorithm can be solved element-wise. Convergence estimates for the elements of the solution to the Riccati equation are provided, directly relating convergence rate to the signal-to-noise ratio in the regression model. An element-wise form of the parameter update equation is also given, where the connection to specific elements of the solution to the Riccati equation is apparent. The SG-algorithm is employed for two applications with audio signals. One is in an acoustic echo cancellation setting where its performance is shown to match that of other well-known estimation techniques, such as the normalized least mean squares and the Kalman filter. When the input is not sufficiently exciting, the studied method performs best of all considered schemes. The other application is the Linz-Donawitz (LD) steel converter. The converter consists of a vessel with molten metal and foam is produced to facilitate chemical reactions. A common problem, usually referred to as slopping, arises when the foam rises above the limits of the vessel and overflows. A warning system is designed, based on the SG-algorithm and change detection methods, to give alarms before slopping occurs. A black-box model relates different sensor values of which one is the microphone signal picked up in the area above the converter. The system detected slopping correctly in 80% of the blows in field studies at SSAB Oxelösund. A practical example of a vision-based system is provided by cavity form estimation in a water model of the steel bath. The water model is captured from the side by a video camera. The images together with a non-linear model are used to estimate important process parameters, related to the heat and mass transport in the LD-converter.
|
286 |
Effects of ionospheric conductance in high-latitude phenomenaBenkevitch, Leonid V 09 February 2006
In this thesis, the relationship between several high-latitude phenomena and the ionospheric conductance in both hemispheres is studied theoretically and experimentally. </p>Theoretically, the high-latitude electrodynamics is studied by considering currents in the magnetosphere-ionosphere system resulting from the ionospheric sheet current redistribution between the conjugate ionospheres. It is shown that strong flow between the conjugate ionospheres, the interhemispheric currents (IHC), can be set up if the conductance distribution is asymmetric in the conjugate ionospheric regions. Such conditions are typical for solstices owing to the differences in the solar illumination. Analytical and numerical modeling shows that IHCs can appear in the regions of strong conductance gradient, more specifically around the solar terminator line, and that the intensity of the IHCs can be comparable to the intensity of the well known Region 1/Region 2 currents. The effect of IHC excitation on observable magnetic perturbations on the ground is investigated. It is shown that in the vicinity of the solar terminator line, the pattern of magnetic perturbation can be such that an apparent equivalent current vortex can be detected. In addition, strong conductance gradients are shown to affect significantly the quality of the ionospheric plasma flow estimates from the ground-based magnetometer data. </p>Experimentally, the effect of the nightside ionospheric conductance on occurrence of substorms, global storm sudden commencement and radar auroras is investigated. To characterize substorm occurrence, new parameters, the derivatives of the classical AE and AO indices, are introduced. It is shown that the seasonal and diurnal variations of these parameters are controlled by the total nightside ionospheric conductance in the conjugate regions. The substorm onsets preferentially occur at low levels of the total conductance, which is consistent with the idea of the substorm triggering through the magnetosphere-ionosphere feedback instability. It is hypothesized that the total conductance affects the global storm onsets as well. To check this idea, the 33-year sudden storm commencement (SSC) data are considered. The semiannual, annual, semidiurnal, and diurnal variations in the SSC occurrence rate are found to be significant and these components exhibit a strong relationship with the total conductance of the high-latitude ionospheres. Finally, the SuperDARN midnight echo occurrence is shown to correlate, for some radars, with the total conductance minima and presumably with electric field maxima, which is consistent with general expectation that the F-region irregularities occur preferentially during times of enhanced electric fields. The gradients of the high-latitude conductance can also lead to significant errors in the plasma convection estimates from the ground-based magnetometers, and to investigate this effect a statistical assessment of the difference between the true plasma convection (SuperDARN) and the magnetometer-inferred equivalent convection direction is performed. The largest differences are found for the transition region between the dark and sunlit ionospheres and in the midnight sector where strong conductance gradients are expected due to particle precipitation. Consideration of regular conductance gradients due to solar illumination improves the agreement between the radar and magnetometer data. Finally, an attempt is made to demonstrate the effects of conductance upon the properties of traveling convection vortices (TCVs). Joint SuperDARN and magnetometer data reveal that there is resemblance between the magnetometer and radar inferred TCV images on a scale of thousands of kilometers. However, on a smaller scale of hundreds of kilometers, significant differences are observed.
|
287 |
Sistema automatizado de detección de defectos en piezas metálicas mediante ensayos no destructivos con ultrasonidosRodríguez González, Cristina 05 July 2012 (has links)
Esta Tesis Doctoral presenta un sistema automatizado de inspección no destructiva de materiales usando ultrasonidos para la detección de heterogeneidades en piezas metálicas, en concreto, de acero al carbono de tipo S275JR. Para ello, se han utilizado guías lineales que se han automatizado con motores paso a paso cuyos movimientos se controlan desde el computador, mediante una aplicación gráfica diseñada específicamente para este trabajo.
Una vez detectados los defectos, se permite una posterior clasificación de los defectos según morfología, posición y tamaño con programas que utilizan algoritmos basados en Reconocimiento de Patrones. Tras su ejecución se obtienen los informes de resultados indicando la estimación de los datos buscados. / This Thesis presents an automated system to the inspection of materials using ultrasounds to the detection of heterogeneities in metallic pieces, in particular, carbon steel S275JR. For that, it used linear guides that have been automated with stepper motors, whose movements are controlled from the computer using a graphic application designed specifically to this research.
When defects are detected, it allows the later classification of defects according to their morphology, size and position with programs that use algorithms based on Pattern Recognition. After execution of the programs, results reports provide an optimal estimation of expected data.
|
288 |
Effects of ionospheric conductance in high-latitude phenomenaBenkevitch, Leonid V 09 February 2006 (has links)
In this thesis, the relationship between several high-latitude phenomena and the ionospheric conductance in both hemispheres is studied theoretically and experimentally. </p>Theoretically, the high-latitude electrodynamics is studied by considering currents in the magnetosphere-ionosphere system resulting from the ionospheric sheet current redistribution between the conjugate ionospheres. It is shown that strong flow between the conjugate ionospheres, the interhemispheric currents (IHC), can be set up if the conductance distribution is asymmetric in the conjugate ionospheric regions. Such conditions are typical for solstices owing to the differences in the solar illumination. Analytical and numerical modeling shows that IHCs can appear in the regions of strong conductance gradient, more specifically around the solar terminator line, and that the intensity of the IHCs can be comparable to the intensity of the well known Region 1/Region 2 currents. The effect of IHC excitation on observable magnetic perturbations on the ground is investigated. It is shown that in the vicinity of the solar terminator line, the pattern of magnetic perturbation can be such that an apparent equivalent current vortex can be detected. In addition, strong conductance gradients are shown to affect significantly the quality of the ionospheric plasma flow estimates from the ground-based magnetometer data. </p>Experimentally, the effect of the nightside ionospheric conductance on occurrence of substorms, global storm sudden commencement and radar auroras is investigated. To characterize substorm occurrence, new parameters, the derivatives of the classical AE and AO indices, are introduced. It is shown that the seasonal and diurnal variations of these parameters are controlled by the total nightside ionospheric conductance in the conjugate regions. The substorm onsets preferentially occur at low levels of the total conductance, which is consistent with the idea of the substorm triggering through the magnetosphere-ionosphere feedback instability. It is hypothesized that the total conductance affects the global storm onsets as well. To check this idea, the 33-year sudden storm commencement (SSC) data are considered. The semiannual, annual, semidiurnal, and diurnal variations in the SSC occurrence rate are found to be significant and these components exhibit a strong relationship with the total conductance of the high-latitude ionospheres. Finally, the SuperDARN midnight echo occurrence is shown to correlate, for some radars, with the total conductance minima and presumably with electric field maxima, which is consistent with general expectation that the F-region irregularities occur preferentially during times of enhanced electric fields. The gradients of the high-latitude conductance can also lead to significant errors in the plasma convection estimates from the ground-based magnetometers, and to investigate this effect a statistical assessment of the difference between the true plasma convection (SuperDARN) and the magnetometer-inferred equivalent convection direction is performed. The largest differences are found for the transition region between the dark and sunlit ionospheres and in the midnight sector where strong conductance gradients are expected due to particle precipitation. Consideration of regular conductance gradients due to solar illumination improves the agreement between the radar and magnetometer data. Finally, an attempt is made to demonstrate the effects of conductance upon the properties of traveling convection vortices (TCVs). Joint SuperDARN and magnetometer data reveal that there is resemblance between the magnetometer and radar inferred TCV images on a scale of thousands of kilometers. However, on a smaller scale of hundreds of kilometers, significant differences are observed.
|
289 |
Radar Observations of MJO and Kelvin Wave Interactions During DYNAMO/AMIE/CINDY2011DePasquale, Amanda Michele 16 December 2013 (has links)
The Madden-Julian Oscillation (MJO), a tropical phenomenon that exists on the time scale of 30-90 days, commonly initiates over the Indian Ocean and slowly propagates into the western Pacific as a series of convective events, which have time scales on the order of hours or days. These events and the overall MJO convective envelope may interact with convectively coupled waves such as Kelvin waves that propagate more rapidly eastward with time scales of 3-5 days. Radar and sounding data collected during the DYNAMO/AMIE/CINDY2011 field campaign from October 2011 to February 2012 in the central Indian Ocean are used to study the interaction between Kelvin waves and the MJO in terms of atmospheric and cloud properties. The focus is on characterizing the precipitation characteristics, convective cloud spectrum, and atmospheric profiles of Kelvin waves during the active and suppressed phases of the MJO to gain insight on MJO initiation.
Characteristics of waves identified using different satellite thresholds and filtering methods are compared. Composites of the radar and sounding observations are calculated for a total of ten Kelvin waves and three MJO events that occurred during the field campaign. Analyzed radar products include convective-stratiform classification of rain rate, rain area, and echo-top heights, as well as cloud boundaries. Sounding data includes profiles of wind speed and direction and relative humidity.
Kelvin waves that occur during the suppressed MJO are convectively weaker than Kelvin waves during the active MJO, but display previously documented structure of low-level convergence and a moist atmosphere prior to the wave passage. During the active MJO, Kelvin waves have stronger convective and stratiform rain, and the entire event is longer, suggesting a slower moving wave. The Kelvin wave vertical structure is somewhat overwhelmed by the convective envelope associated with the MJO. When the MJO is developing, the Kelvin wave displays a moisture-rich environment after the passage, providing deep tropospheric moisture that is postulated to be important for the onset of the MJO.
The convective cloud population prior to MJO initiation shows increased moisture and a population of low- to mid-level clouds. The moisture precedes shallow convection, which develops into the deep convection of the MJO, supporting the discharge-recharge theory of MJO initiation. Additionally, enhanced moisture after the passage of the pre-MJO Kelvin wave could also support the frictional Kelvin-Rossby wave-CISK theory of MJO initiation. With a better understanding of the interaction between the initiation of the MJO and Kelvin waves, the relationships between the environment and the onset of the convection of the MJO can be improved.
|
290 |
Magnetic resonance imaging for improved treatment planning of the prostateVenugopal, Niranjan 11 January 2012 (has links)
Prostate cancer is the most common malignancy afflicting Canadian men in 2011. Physicians use digital rectal exams (DRE), blood tests for prostate specific antigen (PSA) and transrectal ultrasound (TRUS)-guided biopsies for the initial diagnosis of prostate cancer. None of these tests detail the spatial extent of prostate cancer - information critical for using new therapies that can target cancerous prostate. With an MRI technique called proton magnetic resonance spectroscopic imaging (1H-MRSI), biochemical analysis of the entire prostate can be done without the need for biopsy, providing detailed information beyond the non-specific changes in hardness felt by an experienced urologist in a DRE, the presence of PSA in blood, or the “blind-guidance” of TRUS-guided biopsy. A hindrance to acquiring high quality 1H-MRSI data comes from signal originating from fatty tissue surrounding prostate that tends to mask or distort signal from within the prostate, thus reducing the overall clinical usefulness of 1H-MRSI data. This thesis has three major areas of focus: 1) The development of an optimized 1H-MRSI technique, called conformal voxel magnetic resonance spectroscopy (CV-MRS), to deal the with removal of unwanted lipid contaminating artifacts at short and long echo times. 2) An in vivo human study to test the CV-MRS technique, including healthy volunteers and cancer patients scheduled for radical prostatectomy or radiation therapy. 3) A study to determine the efficacy of using the 1H-MRSI data for optimized radiation treatment planning using modern delivery techniques like intensity modulated radiation treatment. Data collected from the study using the optimized CV-MRS method show significantly reduced lipid contamination resulting in high quality spectra throughout the prostate. Combining the CV-MRS technique with spectral-spatial excitation further reduced lipid contamination and opened up the possibility of detecting metabolites with short T2 relaxation times. Results from the in vivo study were verified with post-histopathological data. Lastly, 1H-MRSI data was incorporated into the radiation treatment planning software and used to asses tumour control by escalating the radiation to prostate lesions that were identified by 1H-MRSI. In summary, this thesis demonstrates the clinical feasibility of using advanced spectroscopic imaging techniques for improved diagnosis and treatment of prostate cancer.
|
Page generated in 0.0636 seconds