The violation of expectation (VOE) paradigm and related habituation methods are the primary tools used to study higher-level cognition in preverbal infants. A common assumption of the paradigm is that longer looking to impossible events than possible events is indicative of infants' surprise at witnessing the impossible. Experiments can thus be designed to reveal infants' prior expectations for the behaviour of objects in the environment and so forth. This thesis explored the nature of infants' expectations in VOE-type events, and introduces pupil dilation as a novel dependent measure in tests of infant cognition. Chapter 1 reviews the history of, and rationale for, the use of habituation testing in infants, and presents the case for pupil dilation's potential as a viable and useful measure for tests in infancy. Chapters 2, 3 and 4 present four experiments in which infants are habituated to either possible or impossible events, before being tested on all event types, in order to explore the role of online learning in the formation of infants' expectations in VOE tasks. Both looking times and pupil dilation data were used as dependent measures in each of these tasks. In Chapter 5 Baillargeon's (1987; Baillargeon, Spelke, & Wasserman, 1985) influential 'drawbridge' experiments and the many subsequent replications of them are reviewed before a further replication is introduced in which the novel contribution of pupil dilation data is assessed. The discussion focuses on the findings of the empirical work of this thesis, and concludes that it is crucial to incorporate efforts to refute hypotheses into the designs of tests for infant cognition, and also that pupil data is a valuable complementary measure to, and potentially even superior than, looking times.

Thesis (M.H.A.)--University of Michigan, 1967.

Thesis (M.H.A.)--University of Michigan, 1967.

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An increase in blood flow associated shear stress results in an endothelial dependent increase in vessel diameter (flow mediated vasodilation (FMD)). Assessment of FMD can provide an index of endothelial function. The stimulus profiles that have been used to investigate FMD in human conduit arteries fall into two categories: reactive hyperemia and sustained stimuli. Stimulus-response specificity proposes that the stimulus characteristics (e.g. magnitude, pattern) are essential determinants of the response characteristics (e.g. magnitude, mechanisms). Purpose: To investigate four specific aspects of FMD stimulus-response specificity: 1) The relative importance of the peak vs. the duration of reactive hyperemia in determining FMD response magnitude. 2) The nitric oxide (NO) dependence of FMD following different durations of reactive hyperemia. 3) The impact of sustained shear stress stimulus magnitude on FMD response dynamics and magnitude. 4) FMD dynamics and magnitude in response to steady vs. oscillatory shear stress evoked passively or via exercise. Methods: Doppler ultrasound was applied to the brachial or radial artery to measure blood flow velocity. Vessel diameter was measured with automated edge detection software. Shear rate, an estimate of shear stress was calculated as the blood flow velocity/vessel diameter. Results: 1) The duration of reactive hyperemia is an important determinant of peak FMD magnitude while the independent contribution of the peak shear to FMD is minimal. 2) NO is not obligatory to FMD following either a five or a ten minute duration occlusion. 3) FMD in response to a sustained stimulus is characterized by a generally bi-phasic response with a fast first phase followed by a slower final phase. 4) The endothelium transduces the mean shear stress when it is exposed passive or handgrip exercise induced oscillations in shear stress. Conclusions: The results indicate that future reactive hyperemia studies must account for the stimulus duration when interpreting FMD results. Further, they demonstrate that the role of NO in FMD is unclear and caution against oversimplified conceptual models of FMD mechanisms. FMD in response to sustained stimuli provides information distinct from reactive hyperemia investigations and exercise may provide a valuable stimulus creation technique. / Thesis (Ph.D, Kinesiology & Health Studies) -- Queen's University, 2007-08-16 18:11:18.941

Flow-mediated dilation (FMD) can be used to assess the risk of atherosclerosis; however, an inverse relationship between vessel size and FMD has been identified using reactive hyperemia (RH) to create a shear stress (SS) stimulus in human conduit arteries. RH creates a transient and uncontrolled SS stimulus that is inversely related to baseline arterial diameter. It is therefore unclear whether differences in FMD between groups with non-uniform artery sizes are indicative of differences in vascular health or due to the creation of a greater SS stimulus in smaller vessels. Unlike RH, exercise can effectively create sustained and controlled increases in conduit artery SS. The purpose of this study was to compare the FMD responses of two differently sized upper limb arteries (brachial (BA) and radial artery (RA)) to matched graded levels of SS. Using exercise, three distinct sustained shear rate stimuli were created ((SR)=blood flow velocity/vessel diameter; estimate of SS) in the RA and BA. Artery diameter and mean blood flow velocity were assessed with echo and Doppler ultrasound respectively in 15 healthy male subjects (19-25yrs). Data are means ±SE. Subjects performed 6-min each of adductor pollicis and handgrip exercise to increase SR in the RA and BA respectively. Exercise intensity was modulated to achieve uniformity of SR between the RA and BA at three SR targets (40s-1, 60s-1, 80s-1). Three distinct SR levels were successfully created (steady state exercise: 39.8±0.6s-1, 57.3±0.7s-1, 72.4±1.2s-1; p<0.001 between SR levels). The %FMD at the end of exercise was greater in the RA vs. BA (SR40 RA: 5.4±0.8%, BA: 1.0±0.2%; SR60 RA: 9.8±1.0%, BA: 2.5±0.5%; SR80 RA: 15.7±1.5%, BA: 5.4±0.7%; p<0.001). The mean slope of the within-subject FMD-SR dose-response regression lines was significantly greater in the RA (RA: 0.33±0.04, BA: 0.13±0.02; p<0.001) and a strong within-subjects relationship between FMD and SR was observed in both arteries (RA r2: 0.92±0.02; BA r2: 0.90±0.03). These findings suggest that the response to SS is not uniform across differently sized vessels, which is in agreement with previous RH studies. Future research is required to investigate the potential mechanisms that mediate the functional differences observed between differently sized vessels. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2010-09-22 11:01:26.028

Shear stress is the frictional force exerted on the vascular wall by blood flowing through an artery. It is a major regulator of endothelial cell function, which is essential for vasoprotection and local regulation of vascular tone. Using handgrip exercise (HGEX) to increase shear stress is an increasingly popular method for assessing brachial artery (BA) endothelial cell function via flow-mediated dilation (FMD, dilation which increases with improved endothelial function). However, different exercise duty-cycles (ratio of handgrip relaxation to contraction in seconds) produce different patterns of BA shear stress with different anterograde and retrograde flow magnitudes. PURPOSE: To determine the impact of HGEX duty-cycle on BA %FMD while maintaining a constant mean shear stress. METHODS: N=16 healthy males. BA diameter (BAD) and blood velocity (BV) were assessed via echo and Doppler ultrasound. Shear stress was estimated as shear rate (SR=BV/BAD) and reported as mean SR during the last minute of baseline (target 10 s 1) and each minute of HGEX (75 s-1). Subjects performed 3 six minute HGEX trials on each of 2 separate days (like trials averaged). Each trial was one of 3 randomly ordered HGEX duty-cycles (1:1, 3:1, 5:1). %FMD was calculated as the increase in BAD from baseline to the end of HGEX and at each minute (subset N=10) during HGEX. RESULTS: Data are means ± SD. As intended, mean SR was similar between duty-cycles (main effect, p=0.835), despite significant differences in anterograde and retrograde SR (P<0.001). There was no impact of duty cycle on blood pressure (p=0.188) or heart rate (p=0.131) responses. End exercise %FMD (4.0 ± 1.3%, 4.1 ± 2.2%, 4.2 ± 1.4%, p=0.860) and minute by minute %FMD (main effect p=0.939; interaction, p=0.545) were also not different between duty-cycles. CONCLUSION: Distinct HGEX duty-cycles create markedly different shear stress patterns in the BA. However, duty cycle had no impact on %FMD magnitude suggesting that mean shear stress is the most important stimulus for FMD in the BA. Using a 5:1 duty cycle may yield the best vessel image and diameter measurement quality due to the long period of arm stability between contractions. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2012-09-06 14:31:50.467

Flow mediated dilation (FMD) is a non-invasive test that assesses endothelial health and nitric oxide bioavailability; it is commonly used to examine changes in vascular health due to disease or de-conditioning. Currently, a wide variety of protocols are being used to assess upper and lower extremity conduit artery health. The current project was embarked upon to gain a better understanding of the FMD protocols currently being used to asses conduit artery FMD and how these results impact our understanding of a participant’s vascular health. More specifically occlusion duration, cuff placement and artery location were examined in three commonly examined conduit arteries. The FMD responses in the brachial artery (BA), superficial femoral artery (SFA), and popliteal artery (PA) of ten healthy men, mean age of 27, after five and/or two-minutes of distal occlusion were examined. When the two-minute protocol was performed on the SFA and PA, low-resistance static calf exercise was added to augment the shear stimulus. It was hypothesized that percent FMD and shear stress responses of the SFA and PA would not be significantly different after five-minutes of occlusion, thereby allowing leg conduit artery FMD to be performed on either artery. It was further hypothesized that there would be no significant differences between the shear stress and percent FMD responses of the leg conduit arteries after five or two-minutes of occlusion; inferring that shorter occlusion durations when combines with ischemic muscle contractions can be used to assess SFA or PA FMD. With regards to comparisons between arm and leg conduit arteries, it was hypothesized that there would be significant between limb differences in baseline diameter, FMD and shear stress post five-minutes of distal occlusion. These differences will be used to better understand the effects of artery location and size on conduit artery FMD IV responses. Limitations with the traditional edge-detection method of determining arterial diameter prompted the creation of a new method of measuring artery diameter, the center-based method. It was hypothesized that there would be no significant differences in the percent FMD and time to FMD after five-minutes of BA occlusion (n=7). The results of the current study demonstrated that five-minutes of calf occlusion elicited a significant PA FMD but not a significant SFA FMD. FMD post two-minutes of PA occlusion with exercise was not significantly different than that produced by five-minutes of occlusion. Conversely, two-minutes of calf occlusion with exercise was unable to elicit a SFA FMD response. Significant differences in shear stress and FMD were reported between arm and leg conduit arteries, demonstrating different responses to five-minutes of distal occlusion due to artery size and location. Finally, no significant differences were noted between FMD and time to FMD when the center-based or edge-detection method was used. This study has demonstrated that the calf occlusion protocol was unable to elicit a FMD response in the SFA FMD; this occlusion location is only able to elicit a PA FMD response. Furthermore, two-minutes of occlusion with one-minute of exercise can be used in place of the five-minute protocol to examine PA FMD but not SFA FMD. Differences between arm and leg conduit arteries are noted and it has been suggested that this is likely due to leg conduit artery adaptations to gravity. Lastly, preliminary data suggest that the center-based method is an appropriate method of measuring conduit artery diameter.

The morphological image processing can modify the shapes of objects very efficiently by structure elements. Thus, the morphology processing has recently been applied to industry auto-inspection and medical image processing successfully. In this thesis, we incestigate the efficient processing of morphological image processing by two approaches: quadtree approach and paralell approach. By the quadtree decomposition, any binary image can be decomposed into black and white square blocks with some fixed size of power of 2. Thus, dilation of the whole image can be accomplished by dilating individual decomposed square blocks. On the other hand, any binary image can be presented by bit per pixel basis. Thus, we can exploit the parallel on a personal computer to speed up the set oriented morphological image processing. Experiments have revealed that both approach are much faster than the direct method. The quadtree approach are most advantageous for large structure elements. Whereas, the parralel approach are the fastest for the usual applications.

Flow mediated dilation (FMD) is a non-invasive test that assesses endothelial health and nitric oxide bioavailability; it is commonly used to examine changes in vascular health due to disease or de-conditioning. Currently, a wide variety of protocols are being used to assess upper and lower extremity conduit artery health. The current project was embarked upon to gain a better understanding of the FMD protocols currently being used to asses conduit artery FMD and how these results impact our understanding of a participant’s vascular health. More specifically occlusion duration, cuff placement and artery location were examined in three commonly examined conduit arteries. The FMD responses in the brachial artery (BA), superficial femoral artery (SFA), and popliteal artery (PA) of ten healthy men, mean age of 27, after five and/or two-minutes of distal occlusion were examined. When the two-minute protocol was performed on the SFA and PA, low-resistance static calf exercise was added to augment the shear stimulus. It was hypothesized that percent FMD and shear stress responses of the SFA and PA would not be significantly different after five-minutes of occlusion, thereby allowing leg conduit artery FMD to be performed on either artery. It was further hypothesized that there would be no significant differences between the shear stress and percent FMD responses of the leg conduit arteries after five or two-minutes of occlusion; inferring that shorter occlusion durations when combines with ischemic muscle contractions can be used to assess SFA or PA FMD. With regards to comparisons between arm and leg conduit arteries, it was hypothesized that there would be significant between limb differences in baseline diameter, FMD and shear stress post five-minutes of distal occlusion. These differences will be used to better understand the effects of artery location and size on conduit artery FMD IV responses. Limitations with the traditional edge-detection method of determining arterial diameter prompted the creation of a new method of measuring artery diameter, the center-based method. It was hypothesized that there would be no significant differences in the percent FMD and time to FMD after five-minutes of BA occlusion (n=7). The results of the current study demonstrated that five-minutes of calf occlusion elicited a significant PA FMD but not a significant SFA FMD. FMD post two-minutes of PA occlusion with exercise was not significantly different than that produced by five-minutes of occlusion. Conversely, two-minutes of calf occlusion with exercise was unable to elicit a SFA FMD response. Significant differences in shear stress and FMD were reported between arm and leg conduit arteries, demonstrating different responses to five-minutes of distal occlusion due to artery size and location. Finally, no significant differences were noted between FMD and time to FMD when the center-based or edge-detection method was used. This study has demonstrated that the calf occlusion protocol was unable to elicit a FMD response in the SFA FMD; this occlusion location is only able to elicit a PA FMD response. Furthermore, two-minutes of occlusion with one-minute of exercise can be used in place of the five-minute protocol to examine PA FMD but not SFA FMD. Differences between arm and leg conduit arteries are noted and it has been suggested that this is likely due to leg conduit artery adaptations to gravity. Lastly, preliminary data suggest that the center-based method is an appropriate method of measuring conduit artery diameter.