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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

"Análise comparativa entre sistemas de retenção para próteses auriculares implanto-retidas" / Comparative analyses between retentive systems for implant-retained ear prosthesis

Andréa Alves de Sousa 03 May 2006 (has links)
As próteses auriculares retidas por meio de implantes osseointegráveis proporcionam maior segurança e conforto, melhorando a qualidade de vida dos pacientes. Este trabalho avalia comparativamente a força de resistência à tração dos sistemas de retenção barra/2 clipes, barra/3 clipes, 2 magnetos, e 3 magnetos, empregados para retenção de prótese auricular. Os sistemas de retenção foram submetidos à ciclagem mecânica, com intervalos de 540 ciclos de inserção e remoção para a simulação de períodos de uso clínico, até um total de 3240 ciclos, sendo, a cada intervalo, submetidos ao ensaio mecânico para força de resistência à tração. Os resultados indicam que os sistemas barra/clipes proporcionam maiores retenções do que os sistemas com magnetos e ao mesmo tempo em que a ciclagem mecânica não interfere na relação entre o número de elementos retentores e a retenção proporcionada dentro dos sistemas barra/clip e dos sistemas magnetos. O sistema barra/2 clipes sofre uma perda significantemente maior da capacidade de retenção frente à ciclagem mecânica, sugerindo uma menor longevidade clínica. A relação da capacidade de retenção entre os sistemas não se altera com a ciclagem mecânica uma vez que, a retenção proporcionada pelo sistema barra/3 clipes mantém-se superior, indicando uma maior durabilidade clínica. As retenções proporcionadas pelos sistemas barra/2 clipes e 3 magnetos, bem como aquelas proporcionadas pelos sistemas 2 e 3 magnetos não diferem ao final da ciclagem mecânica, indicando uma durabilidade clínica semelhante. / Placement of osseointegrated implants for retention of ear prosthesis provides greater security and comfort, improving the quality of life of the patients. This work evaluates and compares the retentive mechanical behavior of bar/2 clips, bar/3 clips, 2 magnets, and 3 magnets retention systems, used for implant-retained ear prosthesis. The systems were submitted to mechanical cycling , with intervals of 540 cycles of insertion and removal, for the simulation of clinical periods of function, up to 3240 cycles, being submitted to the mechanical forces essay at each interval. Data were subjected to Tukey-Kramer procedure and the comparative analyses indicate that the bar/clips systems provide different and better retentive forces than the magnet systems and mechanical cycling does not alter the numerical relative performance of the retainer components within the bar/clip or magnet retention system. The bar/2 clips system shows the biggest and statistically significant loss of the retentive forces during mechanical cycling (p<0,05), suggesting a shorter clinical life. The retention provided by the bar/3 clips system remains superior after mechanical cycling, indicating a longer clinical life. The relation between the retention forces presented within the bar/clip systems and magnets systems does change under mechanical cycling. Also, the relation between the bar/2 clips system and 3 magnets system, as well as between 2 and 3 magnets systems do not differ at the end of mechanical cycling , indicating a similar behavior toward clinical life.
32

Development of Metastatic Merkel Cell Carcinoma Following the Excision of Same-Sided Recurrent Auricular Melanoma

Cartwright, Jake K., Snyder, Daniel H., DO, Moreno, Francisco G., MD 06 April 2022 (has links)
Merkel cell carcinoma (MCC) is a rare neuroendocrine malignancy of the skin that is highly aggressive and often metastasizes early. MCC is diagnosed based on histopathological findings and is most commonly treated with surgical resection, which may be accompanied by chemotherapy and/or radiation. This report describes a 55-year-old male with history of recurrent malignant melanoma of the right pinna and subsequent excision. Three years following the excision of melanoma, he presents with a lesion to the right forehead as well as a right-sided neck mass that were found to be metastatic Merkel cell carcinoma. Although there have been reports describing the development of second cancers following the treatment of MCC, the development of MCC after the treatment of other malignancies has not been well-described. Merkel cell carcinoma remains a highly aggressive and frequently metastatic malignancy that should not be overlooked, especially when developed after the diagnosis and treatment of other primary cutaneous malignancies such as melanoma.
33

Transcutaneous Auricular Vagal Nerve Stimulation (taVNS) as a Potential Treatment for Cardiac, Gastric Motility, and Migraine Disorders

Owens, Misty, Dugan, Laura, Farrand, Ariana, Cooper, Coty, Napadow, Vitaly, Beaumont, Eric 07 April 2022 (has links)
Transcutaneous auricular vagal nerve stimulation (taVNS) is a non-invasive method of activating axons in the auricular branch of the vagus nerve through the concha of the outer ear. taVNS is under investigation as an alternative treatment option for a wide range of disorders. Vagal afferent fibers terminate in the nucleus of the solitary tract (NTS) where information is processed and relayed to higher brain regions influencing sympathetic and parasympathetic systems. Due to extensive neuronal connections, it is likely that taVNS could serve as a treatment option for many disorders, specifically cardiac, migraine, and gastric motility disorders. Human fMRI studies have indicated that taVNS elicits neuronal responses within NTS and spinal trigeminal nucleus (Sp5c). Studies have indicated that caudal NTS (cNTS) has substantial connections with the cardiac system, rostral NTS (rNTS) is relevant for gastric motility, and Sp5c is likely involved in migraine disorders due to meningeal connections. Aberrant neuronal signaling is likely responsible for the development of these disorders, and taVNS has the potential to modulate neuronal activity to reestablish homeostatic signaling. In this study, electrophysiological methods were used to interrogate neuronal activity of 50-70 neurons within cNTS, rNTS, and Sp5c following taVNS. A high-impedance tungsten electrode was placed stereotaxically in 15 male Sprague-Dawley rats anesthetized with chloralose. Changes in neuronal firing rates were investigated during and immediately following taVNS by comparing changes in neuronal activity to baseline levels using the software Spike 2 v9.14. Neurons were classified as negative responders if activity decreased more than 20%, positive responders if activity increased more than 20%, or non-responders if activity changes were less than 20%. Six different taVNS parameters were investigated using three frequencies (20, 100, 250Hz) at two intensity levels (0.5, 1.0mA). Data from this study suggest that taVNS can modulate neuronal activity in a frequency and intensity-dependent manner. The greatest positive activation for all 3 brain regions occurred at 20Hz, 1.0mA stimulation where an average of 46% ± 9% neurons showed increased firing compared to 29% ± 2% positive responders for other paradigms. The greatest negative activation for all 3 regions occurred at 100Hz, regardless of intensity, where an average of 33% ± 1% neurons showed reduced firing compared to 15% ± 2% negative responders for remaining paradigms. Based on what is known about cardiac, migraine, and gastric motility disorders, it is likely that taVNS can be used to modulate activity in NTS and Sp5c to provide beneficial treatment options to patients. Specifically, using paradigms yielding decreased activity in Sp5c could improve migraine symptoms, and paradigms increasing activity in cNTS and rNTS could improve cardiac and gastric motility disorders, respectively.
34

3D PRINTED CHITOSAN: PEGDA SCAFFOLDS FOR AURICULAR CARTILAGE REGENERATION BY STEREOLITHOGRAPHY AT VISIBLE LIGHT RANGE

Nimbalkar, Siddharth V. 02 June 2017 (has links)
No description available.
35

Appetitive Responding and the Female Menstrual Cycle: An Investigation into the Post-Auricular Reflex

Izbicki, Emily Victoria January 2012 (has links)
A multitude of research supports that fluctuations in fertility and hormonal shifts in normally cycling females influence changes in female sexual strategies, preferences, and desires across the menstrual cycle. Evolutionary theory posits that in order to maximize reproductive benefits, near ovulation female responses to sexual stimuli alter and cues of sex are more appealing. The post-auricular reflex (PAR) is a psychophysiological reaction that has been linked to motivation and reward, emotion, and appetitive responding. The PAR responds to pleasant stimuli, including stimuli that are relevant to evolutionary themes. The purpose of the current study was to explore the nature of the post-auricular reflex, and in particular, to examine potential shifts in motivation and reward processing of sexual and emotional stimuli across the female menstrual cycle. Ovulation blunted PAR responses to non-erotic categories in normally cycling females, while responses to erotica did not significantly decrease across phases of the menstrual cycle. Ovulation was also found to affect female self-report of sexual desire. These shifts were not seen in females using hormonal birth control. The study results suggest that ovulation shifts female priorities towards reproduction by increasing desire and also decreasing motivations for non-mate-relevant activities. The study also demonstrates the need for greater investigation of the PAR and the appetitive responding system. / Psychology
36

Activation patterns in atrial fibrillation: contributions of body surface potential mapping

Guillem Sanchez, Maria De La Salud 07 January 2009 (has links)
La fibrilación auricular (FA) es una de las arritmias cardiacas más comunes, afectando a alrededor del 10 % de los mayores de 70 años. A pesar de su alta incidencia en la población, los mecanismos que desencadenan y mantienen la FA son inciertos. Aunque existen diversos tratamientos quirúrgicos y farmacológicos, el éxito de los tratamientos contra la FA es muy bajo. La causa de esta baja tasa de éxito de las diferentes terapias es que no existen criterios de selección de pacientes que permitan pronosticar qué terapia puede ser más efectiva para cada paciente. Una de las formas que se han propuesto para determinar el grado de gravedad de la arritmia en cada paciente y, por tanto, poder predecir qué tratamiento es el más apropiado es la medida de la organización auricular. Esta tesis doctoral se enmarca dentro de la determinación no invasiva del grado de organización espacial de la activación del miocardio auricular a partir del estudio de registros multiderivación del electrocardiograma de superficie (ECG). El ECG es una representación simplificada del campo eléctrico del corazón basada en las proyecciones de este campo eléctrico en 8 ejes. Esta simplificación es considerada como aceptable en el caso de ritmos no fibrilantes en los que la activación miocárdica puede ser modelada como un dipolo. Sin embargo, su validez no ha sido demostrada para el caso de ritmos fibrilantes en los cuales la asunción de un modelo dipolar es cuestionable. Uno de los objetivos de esta tesis ha sido la evaluación del electrocardiograma de superficie para la obtención de parámetros espaciales de las ondas de FA. Se compararon las representaciones tridimensionales de las ondas de FA registradas a partir de tres derivaciones ortogonales con las representaciones tridimensionales estimadas a partir del ECG, llegando a la conclusión de que estas representaciones estimadas no son fieles a las representaciones registradas. Los resultados de nuestro estudio ponen de manifiesto que la falta de d / Guillem Sanchez, MDLS. (2008). Activation patterns in atrial fibrillation: contributions of body surface potential mapping [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/3922
37

Modelización y evaluación de factores que favorecen las arritmias auriculares y su tratamiento mediante técnicas quirúrgicas. Estudio de simulación

Tobón Zuluaga, Catalina 07 June 2010 (has links)
Las arritmias auriculares, como es la fibrilación auricular, la taquicardia reentrante o focal y el flúter auricular, son las arritmias cardiacas más frecuentes en la práctica clínica, constituyendo uno de los principales problemas sanitarios actuales. Diferentes trabajos experimentales han demostrado que los mecanismos electrofisiológicos subyacentes a las arritmias auriculares son muy variados, destacando las reentradas anatómicas y funcionales, los focos ectópicos y la existencia de ondas espirales. Adicionalmente, se ha demostrado que las taquicardias inducen alteraciones en las propiedades auriculares que las perpetúan, estos cambios son llamados remodelado auricular. A pesar de los numerosos estudios experimentales realizados, la naturaleza de las anormalidades estructurales y celulares que promueven y perpetúan las arritmias auriculares no han sido determinadas con claridad, debido fundamentalmente, a las limitaciones de dichos estudios experimentales. Un adecuado diagnóstico de los mecanismos que generan y mantienen las arritmias permitiría un tratamiento fármaco-quirúrgico selectivo más optimizado que, aumentando su eficacia, provocará menores daños secundarios sobre el paciente. Actualmente, la modelización matemática y simulación computacional, se han convertido en una potente herramienta de estudio, que puede incluso, sugerir nuevos estudios experimentales o clínicos y nuevas terapias. En esta tesis doctoral, se plantea simular y caracterizar arritmias auriculares, evaluar diferentes factores que favorecen su iniciación y mantenimiento; proponer y evaluar un nuevo método para la localización de fuentes reentrantes y focales, y por último, simular y evaluar la eficacia de diferentes patrones de ablación, sobre la terminación de arritmias auriculares simuladas. La modelización se obtiene a través de ecuaciones diferenciales, las cuales representan las diferentes corrientes que participan en la actividad eléctrica de las células auriculares. / Tobón Zuluaga, C. (2010). Modelización y evaluación de factores que favorecen las arritmias auriculares y su tratamiento mediante técnicas quirúrgicas. Estudio de simulación [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8388
38

Development of new signal analysis methods as preoperative predictors of the Cox-Maze procedure outcome in atrial fibrillation

Hernández Alonso, Antonio 06 November 2017 (has links)
[EN] Atrial fibrilation (AF) is the most common cardiac arrhythmia, however, the knowledge about its causes and mechanisms is still uncompleted. Several studies suggest that atrial structural and electrophysiological remodeling are directly related to its development and perpetuation. To this respect, ECG and preoperative clinical data have been studied to analyze different aspects of atrial remodeling. Nonetheless, there is a lack of studies using ECG parameters to provide valuable clinical information in the study of AF aggressive treatments, such as the Cox-Maze surgery. In this work, ECG parameters such as fibrillatory (f) waves organization and amplitude are studied to predict patient's rhythm from the discharge after the Cox-Maze surgery until a twelve months follow up period. On the other hand, widely used clinical parameters such as age, AF duration and left atrial size (LA size) are studied to assess electrocardiographic results. In addition, clinical information known as a risk factor to develop AF such as weight and body mass index has also been analyze. After assess the individual indices, classification models were created in order to optimize the prediction capability. The results obtained reported that the ECG indices outperform the cinical indices. Nevertheless, the information contained in both types of indices is complementary as the generation of a classification model combining the indices shows. This model exceeded 90% accuracy in each period analyzed. In conclusion, studying the AF information contained in an ECG could provide new data to understand the AF and also could help to develop a reliable method to predict preoperatively the Cox-Maze outcome. / [ES] La fibrilación auricular (FA) es la arritmia cardiaca más comúnmente encontrada en la práctica clínica diaria, sin embargo, todavía no se comprenden completamente los mecanismos fisiológicos que causan el inicio y la perpetuación de la FA. Diversos estudios sugieren que el remodelado estructural y electrofisiológico de la aurícula está relacionado directamente con el desarrollo y perpetuación de la FA. En este sentido, se ha estudiado el ECG e información clínica preoperatoria para analizar distintos aspectos del remodelado. Sin embargo, hay una falta de estudios usando parámetros electrocardiográficos para proporcionar información clínica valiosa en el estudio de tratamientos agresivos de la FA como la cirugía Cox-Maze. En este trabajo, se estudian parámetros electrocardiográficos como la organización de las ondas fibrilatorias y su amplitud para predecir el ritmo de los pacientes desde el momento del alta, tras la cirugía Cox-Maze hasta 12 meses después de la operación. Por otro lado, para evaluar la capacidad de dichos índices, se han utilizado parámetros clínicos ampliamente utilizados como la edad, el tamaño de la aurícula izquierda y el tiempo en FA. Además, se han estudiado también parámetros clínicos conocidos como factores de riesgo para desarrollar FA como son el peso y el índice de masa corporal. Tras analizar la capacidad predictiva de los índices individualmente, éstos se han combinado mediante la generación de modelos de predicción para optimizar la precisión de las predicciones. Los resultados obtenidos señalan que la información contenida en el ECG obtuvo resultados estadísticamente significativos y predicciones más precisas que los índices clínicos. No obstante, el desarrollo de modelos de predicción combinando ambos tipos de índices superó al uso de éstos por separado, con resultados por encima del 90% en todos los períodos estudiados. En conclusión, el análisis del ECG podría aportar nuevos enfoques a la hora de estudiar la FA, y su uso como herramienta de predicción podría ayudar a desarrollar tratamientos más eficientes y personalizados. / [CA] La fibril·lació auricular (FA) és l'arítmia cardíaca més comunament trobada en la pràctica clínica diària, no obstant això, encara no es comprenen completament els mecanismes fisiològics que causen l'inici i la perpetuació de la FA. Diversos estudis suggerixen que el remodelat estructural i electrofisiològic de l'aurícula està relacionat directament amb el desenrotllament i perpetuació de la FA. En este sentit, s'ha estudiat l'ECG i informació clínica preoperatòria per a analitzar distints aspectes del remodelat. No obstant això, hi ha una falta d'estudis usant paràmetres electrocardiográficos per a proporcionar informació clínica valuosa en l'estudi de tractaments agressius de la FA com la cirurgia Cox-Maze. En este treball, s'estudien paràmetres electrocardiográficos com l'organització de les ones fibrilatorias i la seua amplitud per a predir el ritme dels pacients des del moment de l'alta, després de la cirurgia Cox-Maze fins a 12 mesos després de l'operació. Per un altre costat per a avaluar la capacitat dels dits índexs, s'han utilitzat paràmetres clínics àmpliament utilitzats com l'edat, la grandària de l'aurícula esquerra i el temps en FA. A més, s'han estudiat també paràmetres clínics coneguts com a factors de risc per a desenrotllar FA com són el pes i l'índex de massa corporal. Després d'analitzar la capacitat predictiva dels índexs individualment, estos s'han combinat per mitjà de la generació de models de predicció per a optimitzar la precisió de les prediccions. Els resultats obtinguts assenyalen que la informació continguda en l'ECG va obtindre resultats estadísticament significatius i prediccions més precises que els índexs clínics. No obstant això, el desenrotllament de models de predicció combinant ambdós tipus d'índexs va superar a l'ús d'estos per separat, amb resultats per damunt del 90% en tots els períodes estudiats. En conclusió, l'anàlisi de l'ECG podria aportar nous enfocaments a l'hora d'estudiar la FA, i el seu ús com a ferramenta de predicció podria ajudar a desenrotllar tractaments més eficients i personalitzats. / Hernández Alonso, A. (2017). Development of new signal analysis methods as preoperative predictors of the Cox-Maze procedure outcome in atrial fibrillation [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90491
39

Age Estimation from the Auricular Surface of the Ilium: A Revised Method

Buckberry, Jo, Chamberlain, A. January 2002 (has links)
No / A revised method for estimating adult age at death using the auricular surface of the ilium has been developed. It is based on the existing auricular surface aging method of Lovejoy et al. ([1985] Am. J. Phys. Anthropol. 68:15-28), but the revised technique is easier to apply, and has low levels of inter- and intraobserver error. The new method records age-related stages for different features of the auricular surface, which are then combined to provide a composite score from which an estimate of age at death is obtained. Blind tests of the method were carried out on a known-age skeletal collection from Christ Church, Spitalfields, London. These tests showed that the dispersion of age at death for a given morphological stage was large, particularly after the first decade of adult life. Statistical analysis showed that the age-related changes in auricular surface are not significantly different for males and females. The scores from the revised method have a slightly higher correlation with age than do the Suchey-Brooks pubic symphysis stages. Considering the higher survival rates of the auricular surface compared with the pubic symphysis, this method promises to be useful for biological anthropology and forensic science.
40

Forensic age estimation based on the trabecular bone changes of the pelvic bone using post-mortem CT.

Villa, C., Hansen, M.N., Buckberry, Jo, Cattaneo, C., Lynnerup, N. January 2013 (has links)
Yes / We analyzed the trabecular bone changes in the pubic bone (PB) and in the auricular surface (AS) of the ilium using 319 CT scans of cadavers to estimate the age. Although the sharpness of the trabecular structure decreases in CT images when soft tissues are present, we identified four phases for the changes in PB and five in AS; a juvenile trait in PB and a senile trait in AS helped narrow the age range. High correlation with age was identified for both sexes in PB (F 0.89; M 0.75) and in AS (F 0.85; M 0.71) used independently or combined (F 0.91; M 0.78). The old adults (>60 years) could be evaluated with better accuracy and discriminated in several phases. We found low inter-observer error and low inaccuracy (about 6 years, mean for all age ranges). The method is robust with respect to slice thickness, display window and kernel within the tested ranges.

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