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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.
1

The role of natural image structure in visual detection of photometric changes

Yoonessi, Ali. January 1900 (has links)
Thesis (Ph.D.). / Written for the Dept. of Ophthalmology, Neurology and Neurosurgery. Title from title page of PDF (viewed 2008/03/12). Includes bibliographical references.
2

A study of the pressoreceptive thresholds of human teeth thesis submitted in partial fulfillment ... orthodontics ... /

Lee, James F. January 1965 (has links)
Thesis (M.S.)--University of Michigan, 1965.
3

A study of the pressoreceptive thresholds of human teeth thesis submitted in partial fulfillment ... orthodontics ... /

Lee, James F. January 1965 (has links)
Thesis (M.S.)--University of Michigan, 1965.
4

Identifying pre-operative predictors of post-surgical pain in adolescents using quantitative sensory testing

Plocienniczak, Michal 22 January 2016 (has links)
Objective: Research on the role of acute post-surgical pain in children is extremely important in order to have a positive influence on pre-surgical preparation and post-surgical care and to prevent pain from becoming chronic, which can extend decades into adulthood. This project aims to identify predictors of acute post-surgical pain in adolescents with idiopathic scoliosis undergoing spinal fusion by utilizing sensory thresholds obtained through quantitative sensory testing (QST). Methods: Eligible candidates were Adolescent Idiopathic Scoliosis (AIS) patients ages 10-17 who have been recommended to receive elected spinal fusion surgery at Boston Children's Hospital (BCH). 9 successfully recruited and enrolled participants underwent a full series of QST tests on their palmar thenar eminence (non-surgical site), and their lower back (surgical site). Patients' Light Touch Detection Threshold (LTDT) and Pain Detection Threshold (PDT) scores were determined using Von Frey Hairs. Patients' Pressure-Pain Sensation Threshold (PPST) scores were determined using a pressure algometer. Patients' Warm/Cool and Hot/Cold Pain Detection Thresholds were detected using a calibrated thermode strapped to the skin. Following the full-series of QST tests, and after the patient was discharged from the hospital, a retrospective chart review was conducted to determine the patients': Age at Surgery, Gender, Number of Vertebrae Fused (Fusion Length), Length of Surgery, Pre-Operative Self-Identified Pain Level (NRS 0-10), Average Post-Operative Acute-Phase Self-Identified Pain Level (NRS 0-10), and daily Pain Medication Doses (Opiate Vs. Non-Opiate Vs. Total). Correlation calculations were done between each variable, including those determined through QST as well as retrospective chart review. For every QST test, each patient's individual score was compared to the cohort's median score, which helped determine whether the patient was either hyper- or hyposensitive for that particular test. For each QST test, these hyper- and hyposensitive groups were then compared to see if there were any significant differences in post-operative pain experienced. Results: Due to the low number of participants (N = 9), the results should be considered preliminary. Correlation studies demonstrate that pre-operative pain was significantly positively correlated with post-operative pain (r = 0.81, p <0.05), indicating that patients who are pre-operatively already in pain, will consequently experience the most pain post-operatively. Additionally, fusion length had a strong positive correlation to acute post-operative opiate pain medication administration (r = 0.71, P < 0.05), indicating that patients who had more vertebrae fused were given more opiates. Through the use of QST, we discovered that patients hypersensitive in the LTDT-Spine QST test experienced significantly less pain post-operatively (3.22 NRS 0-10) than that experienced by hyposensitive patients (5.52 NRS 0-10) from the same test. Identical results were discovered in patients determined hyper- and hyposensitive using the PPST-Spine test, respectively. Retrospective chart review data show that these hyposensitive patients were experiencing greater pain pre-operatively (0.75 NRS 0-10) than that experienced by the hypersensitive patients (0 NRS 0-10), which may have contributed to the hyposensitive cohort's greater post-operative pain. Although insignificant, patients hypersensitive in the Hot Pain - Spine QST test experienced greater post-operative pain (4.72 NRS 0-10) than that experienced by hyposensitive patients in the same test (4.06 NRS 0-10). Conclusions: The goal of this study was to determine a substantiated hypothesis to test in the future, using larger pediatric cohorts. Even though it initially appears that the hyposensitive patients, as determined by the LTDT-Spine and PPST-Spine QST tests, experienced greater post-operative pain, one must consider the fact that this hyposensitive group experienced a significantly greater amount of pre-operative pain. Not only has pre-operative pain been proven to have a strong correlation to post-operative pain in this study, it has also been proven in other larger studies as well. Other studies have identified a test similar to the Hot Pain - Spine QST test as a potential predictor of post-operative pain. The present study's results, although insignificant, share the same conclusion that hypersensitive patients determined through Hot Pain - Spine QST test experience greater post-operative pain. Therefore, the hypothesis to test in the future in pediatric cohorts should read: AIS patients with no pre-operative pain who demonstrate increased sensitivity to hot pain on their surgical site via thermal stimulation (QST) will experience greater post-operative pain in the acute-recovery phase.
5

Análise comparativa das alterações da sensibilidade cutânea após abdominoplastias / Comparative analysis of the alterations of cutaneous sensibility after abdominoplasties

Fels, Klaus Werner 31 July 2008 (has links)
A abdominoplastia é uma das cirurgias plásticas mais realizadas. A associação entre a lipoaspiração e o descolamento reduzido trouxe uma nova perspectiva em relação à maior preservação da inervação cutânea sensitiva. Novos métodos de avaliação de sensibilidade têm permitido melhor quantificação e uma análise mais completa da evolução pós-operatória. Foi realizado um estudo do tipo caso-controle comparando-se um grupo controle de pacientes não operadas, um grupo de pacientes que realizou abdominoplastia convencional e um grupo que realizou abdominoplastia associada a lipoaspiração e descolamento reduzido. Para a avaliação da sensibilidade, utilizou-se o PSSD (dispositivo específico de sensibilidade de pressão), testes para sensibilidade térmica e dolorosa (agulhas). O PSSD foi aplicado em nove regiões da parede abdominal anterior para determinação do limiar cutâneo de pressão (LCP) em duas modalidades sensoriais: um ponto estático (1PE), para avaliação de fibras de adaptação lenta, e um teste dinâmico (1PD), para avaliação de fibras de adaptação rápida. Quanto maior o LCP, menor a sensibilidade na região. Foram incluídas 46 pacientes nos três grupos. O grupo controle continha 10 pacientes, cujos limiares cutâneos de pressão (LCP) variaram de 0,82 a 0,84 e de 0,77 a 0,79 g/mm2 para 1PE e 1PD, respectivamente. O grupo de abdominoplastia convencional (AC) continha 14 pacientes com medidas em dois momentos de pós-operatório, precoce (5,75 meses) e tardio (17,36 meses). Os resultados demonstraram LCPs entre 1,02 e 39,94 para a medida precoce e 0,79 e 20,07 g/mm2 para a medida tardia. O grupo de abdominoplastia associada a lipoaspiração (LA) continha 22 pacientes com acompanhamento de 5,72 meses (precoce) e 14,91 meses (tardio). Os resultados demonstraram LCPs entre 0,62 e 4,98 para a medida precoce e 0,67 e 1,91 g/mm2 para a medida tardia. A análise estatística usou método de análise de variância com medidas repetidas. O nível de significância adotado foi de 0,05. A análise estatística para a medida de 1PE revelou redução da sensibilidade significante no grupo AC em todas as regiões (precoce e tardia). No grupo LA, houve redução da sensibilidade apenas nas regiões de mesogastro e hipogastro na medida precoce com regularização total na análise tardia. Entretanto, a análise estatística para 1PD revelou, no grupo AC, redução na medida precoce em todas as regiões e redução apenas das regiões centrais (mesogastro e hipogastro) na análise tardia. Já no grupo LA, todas as medidas estavam normalizadas na análise precoce e tardia. A análise da sensibilidade térmica e dolorosa revelou reduções centrais, especialmente nas regiões de mesogastro e hipogastro no grupo AC. O grupo LA revelou áreas de anestesia térmica e dolorosa apenas em pequena área do hipogastro. Concluiu-se que as três modalidades sensoriais (tátil, térmica e dolorosa) são mais preservadas no grupo LA que no grupo AC. A recuperação da medida 1PD é mais rápida que a medida de 1PE / Abdominoplasties are common plastic surgery procedures. New techniques associating lipoaspiration with selective undermining are bringing new perspectives with regard to the preservation of cutaneous sensibility. New methods of evaluation of cutaneous sensibility have allowed researchers to do a more complete analysis. This is a case-control study comparing a control group of patients non operated with one group submitted to conventional abdominoplasty and another group submitted to abdominoplasty associating lipoaspiration with selective undermining. The abdominal surface was divided into nine regions for sensibility evaluation. Superficial tactile sensibility was tested using the Pressure Specified Sensory Device (PSSD) which allows the determination of the cutaneous pressure threshold (static and moving). Tests of pain and thermal sensibility were also performed. A total of 46 patients were divided in three groups. In the control group, with 10 patients, the cutaneous pressure thershold (CPT) oscilated from 0.82 to 0.84 and from 0.77 to 0.79 g/mm2 for one point static and one point moving sensibility evaluations, respectively. The group of patients submitted to conventional abdominoplasty (AC), with 14 patients, was evaluated in two moments of follow-up: early (mean of 5.75 months after surgical procedure) and late (17.36 months). The results showed CPTs betwen 1.02 and 39.94 in the early follow-up, versus 0.79 to 20.07 g/mm2 in the late follow-up. The group submitted to abdominoplasty associated with lipoaspiration and selective underminig (LA) had 22 patients, with a mean follow-up period of 5.75 (early) and 14.91 (late) months. The results showed CPTs betwen 0.62 and 4.98 (early) and 0.67 and 1.91 g/mm2 (late). The statistical analysis was conducted with the analysis of variance with repeated measurements. The level of significance adopted was p < 0.05. The estatistical analysis for one point static showed significant reduction of sensibility in the group AC in all abdominal regions (in the early and late follow-up periods). The group LA presented reduced CPT only in the mesogastric and hypogastric in the early evaluation; the late evaluation was normal. On the other hand, the analisis of one point moving showed, in the group AC, a reduction of early evaluation measurement in all abdominal regions and a reduction only in central regions (mesogastric and hypogastric) in the late. The LA group presented normal in all measurements. The analysis of pain and thermal sensibility shows that the centermost regions of the abdomen, mesogastric and hypogastric, presented the highest anesthesia index in the AC group. The LA group showed just some islands in the hipogastric regions. The recuperation of the 1PD evaluation was faster than the 1PE. In conclusion, the three sensibilities (tactile, thermal and pain) were more preservated in the LA group. Abdominoplasty with lipoaspiration could be considered a better choice than conventional abdominoplasty considering the preservation of cutaneous sensibility
6

Pain, its assessment and treatment using sensory stimulation techniques : methodological considerations /

Lund, Iréne, January 2006 (has links)
Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 5 uppsatser.
7

The limits to absolute visual sensitivity /

Field, Gregory Darin, January 2004 (has links)
Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 91-102).
8

Análise comparativa das alterações da sensibilidade cutânea após abdominoplastias / Comparative analysis of the alterations of cutaneous sensibility after abdominoplasties

Klaus Werner Fels 31 July 2008 (has links)
A abdominoplastia é uma das cirurgias plásticas mais realizadas. A associação entre a lipoaspiração e o descolamento reduzido trouxe uma nova perspectiva em relação à maior preservação da inervação cutânea sensitiva. Novos métodos de avaliação de sensibilidade têm permitido melhor quantificação e uma análise mais completa da evolução pós-operatória. Foi realizado um estudo do tipo caso-controle comparando-se um grupo controle de pacientes não operadas, um grupo de pacientes que realizou abdominoplastia convencional e um grupo que realizou abdominoplastia associada a lipoaspiração e descolamento reduzido. Para a avaliação da sensibilidade, utilizou-se o PSSD (dispositivo específico de sensibilidade de pressão), testes para sensibilidade térmica e dolorosa (agulhas). O PSSD foi aplicado em nove regiões da parede abdominal anterior para determinação do limiar cutâneo de pressão (LCP) em duas modalidades sensoriais: um ponto estático (1PE), para avaliação de fibras de adaptação lenta, e um teste dinâmico (1PD), para avaliação de fibras de adaptação rápida. Quanto maior o LCP, menor a sensibilidade na região. Foram incluídas 46 pacientes nos três grupos. O grupo controle continha 10 pacientes, cujos limiares cutâneos de pressão (LCP) variaram de 0,82 a 0,84 e de 0,77 a 0,79 g/mm2 para 1PE e 1PD, respectivamente. O grupo de abdominoplastia convencional (AC) continha 14 pacientes com medidas em dois momentos de pós-operatório, precoce (5,75 meses) e tardio (17,36 meses). Os resultados demonstraram LCPs entre 1,02 e 39,94 para a medida precoce e 0,79 e 20,07 g/mm2 para a medida tardia. O grupo de abdominoplastia associada a lipoaspiração (LA) continha 22 pacientes com acompanhamento de 5,72 meses (precoce) e 14,91 meses (tardio). Os resultados demonstraram LCPs entre 0,62 e 4,98 para a medida precoce e 0,67 e 1,91 g/mm2 para a medida tardia. A análise estatística usou método de análise de variância com medidas repetidas. O nível de significância adotado foi de 0,05. A análise estatística para a medida de 1PE revelou redução da sensibilidade significante no grupo AC em todas as regiões (precoce e tardia). No grupo LA, houve redução da sensibilidade apenas nas regiões de mesogastro e hipogastro na medida precoce com regularização total na análise tardia. Entretanto, a análise estatística para 1PD revelou, no grupo AC, redução na medida precoce em todas as regiões e redução apenas das regiões centrais (mesogastro e hipogastro) na análise tardia. Já no grupo LA, todas as medidas estavam normalizadas na análise precoce e tardia. A análise da sensibilidade térmica e dolorosa revelou reduções centrais, especialmente nas regiões de mesogastro e hipogastro no grupo AC. O grupo LA revelou áreas de anestesia térmica e dolorosa apenas em pequena área do hipogastro. Concluiu-se que as três modalidades sensoriais (tátil, térmica e dolorosa) são mais preservadas no grupo LA que no grupo AC. A recuperação da medida 1PD é mais rápida que a medida de 1PE / Abdominoplasties are common plastic surgery procedures. New techniques associating lipoaspiration with selective undermining are bringing new perspectives with regard to the preservation of cutaneous sensibility. New methods of evaluation of cutaneous sensibility have allowed researchers to do a more complete analysis. This is a case-control study comparing a control group of patients non operated with one group submitted to conventional abdominoplasty and another group submitted to abdominoplasty associating lipoaspiration with selective undermining. The abdominal surface was divided into nine regions for sensibility evaluation. Superficial tactile sensibility was tested using the Pressure Specified Sensory Device (PSSD) which allows the determination of the cutaneous pressure threshold (static and moving). Tests of pain and thermal sensibility were also performed. A total of 46 patients were divided in three groups. In the control group, with 10 patients, the cutaneous pressure thershold (CPT) oscilated from 0.82 to 0.84 and from 0.77 to 0.79 g/mm2 for one point static and one point moving sensibility evaluations, respectively. The group of patients submitted to conventional abdominoplasty (AC), with 14 patients, was evaluated in two moments of follow-up: early (mean of 5.75 months after surgical procedure) and late (17.36 months). The results showed CPTs betwen 1.02 and 39.94 in the early follow-up, versus 0.79 to 20.07 g/mm2 in the late follow-up. The group submitted to abdominoplasty associated with lipoaspiration and selective underminig (LA) had 22 patients, with a mean follow-up period of 5.75 (early) and 14.91 (late) months. The results showed CPTs betwen 0.62 and 4.98 (early) and 0.67 and 1.91 g/mm2 (late). The statistical analysis was conducted with the analysis of variance with repeated measurements. The level of significance adopted was p < 0.05. The estatistical analysis for one point static showed significant reduction of sensibility in the group AC in all abdominal regions (in the early and late follow-up periods). The group LA presented reduced CPT only in the mesogastric and hypogastric in the early evaluation; the late evaluation was normal. On the other hand, the analisis of one point moving showed, in the group AC, a reduction of early evaluation measurement in all abdominal regions and a reduction only in central regions (mesogastric and hypogastric) in the late. The LA group presented normal in all measurements. The analysis of pain and thermal sensibility shows that the centermost regions of the abdomen, mesogastric and hypogastric, presented the highest anesthesia index in the AC group. The LA group showed just some islands in the hipogastric regions. The recuperation of the 1PD evaluation was faster than the 1PE. In conclusion, the three sensibilities (tactile, thermal and pain) were more preservated in the LA group. Abdominoplasty with lipoaspiration could be considered a better choice than conventional abdominoplasty considering the preservation of cutaneous sensibility
9

The chromatic selectivity of visual crowding

Kennedy, Graeme J., Whitaker, David J. January 2010 (has links)
Precortical vision is mediated by three opponent mechanisms that combine receptoral outputs to form a luminance channel (L + M) and two chromatic channels, red-green (L/M) and blue-yellow (S/L + M). Here we ask the extent to which these basic color opponent mechanisms interact in the phenomenon of crowding, where nearby targets interfere with the processing of a central test target. The task was to identify the orientation of a Gabor patch while an annular plaid surrounded the patch. The radius of the annulus was varied in order to produce different separations of the test and flanker. The chromatic content of the Gabor and the annulus could be varied independently along the (L + M), (L/M), and (S/L + M) cardinal axes. For all targets, when the target and flanker shared the same chromaticity, performance decreased with decreasing separation of the target and annulus, i.e., a typical crowding effect was seen. When the test and flanker isolated different chromatic mechanisms, very little crowding was observed, even at the minimum separation of test target and annulus. In addition to this, intermediate chromaticities were found to produce intermediate levels of crowding. Finally, crowding effects using "half-wave rectified" stimuli suggest a locus for crowding effects beyond the level of color opponent mechanisms.
10

Avaliação da confiabilidade interexaminador dos testes sensoriais quantitativos em estruturas mastigatórias / Evaluation of interrater reliability of quantitative sensory testing in the masticatory structures

Araújo Junior, Everardo Napoleão Santana de 29 March 2018 (has links)
Este estudo estimou a confiabilidade interexaminador e a concordância da avaliação somatossensorial realizada na região do músculo masseter e da articulação temporomandibular (ATM) em um grupo de voluntários saudáveis do sexo feminino e masculino. Quarenta participantes saudáveis (20 homens e 20 mulheres) foram avaliados em duas sessões por dois examinadores diferentes. Os testes aplicados foram limiar de detecção ao frio (CDT, siglas em inglês), limiar de detecção ao calor (WDT), limiar sensorial térmico (TSL), limiar de dor ao frio (CPT), limiar de dor ao calor (HPT), limiar de detecção mecânica (MDT), limiar de dor mecânica (MPT) Razão da somação temporal (WUR) e o limiar de dor a pressão (PPT). ANOVA, coeficiente de correlação intraclasse (ICC) e erro padrão de mensuração (SEM) foram computados ( = 5%). O intervalo de confiança de 95% sem sobreposição (IC 95%) dos valores de ICC foi considerado significativamente diferente. Setenta e sete por cento dos valores de ICC de todas as medidas do QST variaram entre razoável a excelente (ICCs: 0,47-0,97). No entanto, a confiabilidade do WDT, TSL e HPT do masseter foi significativamente maior do que da ATM, enquanto que a confiabilidade de MDT da ATM foi maior do que do músculo masseter. Além disso, a seguinte combinação de teste/sítio apresentou os menores valores de ICC nas mulheres: HPT e MDT da ATM e MPT de ambos os sítios ATM e masseter. Para o erro padrão de mensuração, os maiores valores foram apresentados no CPT e MPT. A avaliação somatossensorial geral das estruturas de mastigatórias realizadas por dois examinadores pode ser considerada suficientemente confiável para discriminar os participantes. No entanto, as possíveis influências do sitio e do sexo nos parâmetros de reprodutibilidade devem ser levadas em consideração para uma interpretação e aplicação clínica apropriadas. / This study estimated the interrater reliability and agreement of the somatosensory assessment performed at masseter and temporomandibular joint (TMJ) region in a group of healthy female and male participants. Forty healthy participants (20 men and 20 men) were evaluated in two sessions by two different examiners. Cold detection threshold (CDT), warm detection threshold (WDT), thermal sensory limen (TSL), cold pain threshold (CPT), heat pain threshold (HPT), mechanical detection threshold (MDT), mechanical pain threshold (MPT), wind-up ratio (WUR) and pressure pain threshold (PPT) were assessed on the skin overlying masseter body and TMJ. Mixed ANOVA, Intraclass Correlation Coefficients (ICC) and standard error of measurement (SEM) were applied to the data (=5%). Non-overlapping 95% confidence intervals (95% CI) of ICC values were considered significantly different. The ICC values of 77% of all QST measurements were considered fair to excellent (ICCs: 0.47-0.97). However, the reliability of WDT, TSL and HPT of masseter was significantly higher than TMJ, whereas the MDT reliability of TMJ was higher than masseter. In addition, the following combination of test/sites presented significantly lower ICCs for women: HPT, MDT of TMJ and MPT of both TMJ and masseter. Finally, the highest SEM values were presented for CPT and MPT. The overall somatosensory assessment of the masticatory structures performed by two examiners can be considered sufficiently reliable to discriminate participants. Nevertheless, possible site and sex influences on the reproducibility parameters should be take into account for an appropriate interpretation and clinical application.

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