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The angular resolution of an imaging system is sharply bounded by the diffraction limit, a fundamental property of electromagnetic radiation propagation. In order to increase resolution and see finer details of remote objects, the sizes of telescopes and cameras must be increased. As the size of the optics increase, practical problems and costs increase rapidly, making sparse aperture systems attractive for some cases. The method of Intensity Correlation Imaging (ICI) provides an alternative method of achieving high angular resolution that allows a system to be built with less stringent precision requirements, trading the mechanical complexity of a typical sparse aperture for increased computational requirements. Development of ICI has stagnated in the past due to the inadequacies of computational capabilities, but the continued development of computer technologies now allow us to approach the image reconstruction process in a new, more e ffctive manner. This thesis uses estimation methodology and the concept of transverse phase diversity to explore the modern bounds on the uses of ICI. Considering astronomical observations, the work moves beyond the traditional, single-parameter uses of ICI, and studies systems with many parameters and complex interactions. It is shown that ICI could allow significant new understanding of complex multi-star systems. Also considered are exoplanet and star-spot measurements; these are less promising due to noise considerations. Looking at the Earth imaging problem, we find significant challenges, particularly related to pointing requirements and the need for a large field-of-view. However, applying transverse phase diversity (TPD) measurements and a least-squares estimation methodology solves many of these problems and re-opens the possibility of applying ICI to the Earth-imaging problem. The thesis presents the TPD concept, demonstrates a sample design that takes advantage of the new development, and implements reconstruction techniques. While computational challenges remain, the concept is shown to be viable. Ultimately the work presented demonstrates that modern developments greatly enhance the potential of ICI. However, challenges remain, particularly those related to noise levels.

Neurovascular models have played an important role in understanding neuronal function or medical conditions. In the past few decades, only small volumes of neurovascular data have been available. However, huge data sets are becoming available with high throughput instruments like the Knife-Edge Scanning Microscope (KESM). Therefore, fast and robust tracing methods become necessary for tracing such large data sets. However, most tracing methods are not effective in handling complex structures such as branches. Some methods can solve this issue, but they are not computationally efficient (i.e., slow). Motivated by the issue of speed and robustness, I introduce an effective and efficient fiber tracing algorithm for 2D and 3D data. In 2D tracing, I have implemented a Moving Window (MW) method which leads to a mathematical simplification and noise robustness in determining the trace direction. Moreover, it provides enhanced handling of branch points. During tracing, a Cubic Tangential Trace Spline (CTTS) is used as an accurate and fast nonlinear interpolation approach. For 3D tracing, I have designed a method based on local maximum intensity projection (MIP). MIP can utilize any existing 2D tracing algorithms for use in 3D tracing. It can also significantly reduce the search space. However, most neurovascular data are too complex to directly use MIP on a large scale. Therefore, we use MIP within a limited cube to get unambiguous projections, and repeat the MIP-based approach over the entire data set. For processing large amounts of data, we have to automate the tracing algorithms. Since the automated algorithms may not be 100 percent correct, validation is needed. I validated my approach by comparing the traced results to human labeled ground truth showing that the result of my approach is very similar to the ground truth. However, this validation is limited to small-scale real-world data due to the limitation of the manual labeling. Therefore, for large-scale data, I validated my approach using a model-based generator. The result suggests that my approach can also be used for large-scale real-world data. The main contributions of this research are as follows. My 2D tracing algorithm is fast enough to analyze, with linear processing time based on fiber length, large volumes of biological data and is good at handling branches. The new local MIP approach for 3D tracing provides significant performance improvement and it allows the reuse of any existing 2D tracing methods. The model-based generator enables tracing algorithms to be validated for large-scale real-world data. My approach is widely applicable for rapid and accurate tracing of large amounts of biomedical data.

The present study was undertaken to determine the effects of varying light intensities on the morphology and physiology of the soft coral Pachyclavularia violacea. The soft corals P. violacea were treated by LED light and the illumination ranged from 50 to 200 £gmol photon m-2 s-1, i.e. high light (200 £gmol photon m-2 s-1), medium light (140 £gmol photon m-2 s-1), medium-low light (100 £gmol photon m-2 s-1 and low light (50 £gmol photon m-2 s-1). The theca length, the density of zooxanthellae and the concentrations of chlorophyll a and proteins were measured to evaluate the response of P. violacea to different light intensities. A significant longer theca length was found in the group of medium-low light (5¡V 9mm) than the groups of high and low light intensities (1-2mm) (p<0.001). And, the theca length in the groups of medium and medium-low was more close to their source population. Over the 6-month experimental periods, the densities of zooxanthellae in the groups of medium and medium-low were in the range of 1.5 ~3.8 x 105 (N/mg) which were significantly higher than other groups (p<0.01). The concentrations of chlorophyll a in the low light group were 0.5~ 2.0 (ng/mg) during the experimental periods which were significantly higher than other groups (p<0.05). In the fifth and sixth months, the concentrations of chlorophyll a per zooxanthellae in the group of medium-low were in the range of 0.4~5.8 Chl. a ¡Ñ 10-5 (ng/zoox.) which were significantly higher than other groups (p<0.01). The protein content in the group of low light was significantly lower than other groups in the fifth month. And, the protein contents were decreased significantly in all groups in the sixth month. Based on the results, it is concluded that theca length and the density of zooxanthellae were sensitive responses to light adaptation. The light intensity about 100 £gmol photon m-2 s-1 might be an appropriate range to culture the soft coral P. violacea because the theca length in the group was close to its source population.

The laser-induced holographic grating technique was employed to study the dynamic of the intensity grating formation in the azo-dye doped liquid crystals. The liquid crystal material in this study has several mesomorphic phases: Smectic C, Smectic A, Nematic and Isotropic. The first order of diffraction in the mesomorphic phases have been investigated by changing the polarizations of the probe beam.

The goal of this research was to extend the investigation into a method to represent and analyze the stress field around two parallel edge cracks in a finite body. The Westergaard-Schwarz method combined with the local collocation method was used to analyze different cases of two parallel edge cracks in a finite body. Using this method a determination of when two parallel edge cracks could be analyzed as isolated single edge cracks was determined Numerical experimentation was conducted using ABAQUS. It was used to obtain the coordinate and stress information required in the local collocation method. The numerical models were created by maintaining one crack at a fixed length while varying the length of the second crack as well as the separation distance of the two cracks. The results obtained through the local collocation method were compared with the finite element obtained J-Integrals to verify the accuracy of the results. The results obtained in the analysis showed that the major factor in determining when the second crack’s stress field has to be considered was the crack separation distance. It was found that a reduction in the second crack’s length did not have a significant effect on overall stress intensity factors of the fixed crack. A larger change in the opening mode stress intensity factor can be seen by varying the crack separation distance. As well as seeing a steady reduction in shear mode stress intensity factors as the crack separation was increased. The results showed that after a certain crack separation distance the two cracks could be analyzed separately without introducing significant error into the stress field calculations.

To understand the function of the cardiovascular system, the propagation of waves in arteries has to be investigated, since they carry information which can be used for the prevention and diagnosis of cardiovascular diseases. The main goal of this thesis is to improve the understanding of wave propagation in central and peripheral arteries studying the local hemodynamics of the ascending aorta, the carotid artery and the femoral artery by analysing human, animal and in vitro data. Also, another aim is to introduce a technique for non-invasive determination of the local arterial distensibility, the wave speed, and wave intensities. Arterial hemodynamics is here studied using wave intensity analysis, a time domain technique based on pressure and velocity measurements that is derived from the 1D theory of wave propagation in elastic tubes. Also, variations of this technique were used, such as (i) the non-invasive wave intensity analysis that relies on diameter and velocity measurements and (ii) the reservoir-wave approach in which pressure is considered the sum of a pressure due to the elastic properties of the arteries and a pressure due to the travelling wave. To identify the correct analysis to describe the wave propagation in the ascending aorta using pressure and velocity measurements, the hemodynamics of the canine ascending aorta was studied invasively using the traditional wave intensity (or waveonly) analysis and the reservoir-wave approach in both control condition and during total aorta occlusions in order to provide clear reflection sites. The models produced a remarkably similar wave intensity curves, although the intensity magnitudes were different. The reservoir-wave model always yielded lower values for all hemodynamic parameters studied. Both models led to the conclusion that distal occlusions have little or no effect on hemodynamics in the ascending aorta. Since the ascending aorta is not an accessible vessel its examination in clinical routine is challenging. More superficial arteries, such as carotid, radial, brachial and femoral arteries, might be easier to examine, in particular using ultrasound equipment that is normally available in the clinic. These considerations led to the second study of this thesis that is the introduction of a new technique for the non-invasive determination of arterial distensibility, local wave speed and wave intensities to study arterial hemodynamics in humans. The technique relies only on diameter and velocity measurements that can be obtained using ultrasound. In particular, the technique was used for the first time to study the hemodynamic of the carotid and femoral arteries in a large population of healthy humans to investigate the changes with age and gender. The carotid artery was more affected by the aging process than the femoral artery, even in healthy subjects. Local wave speed, distensibility and hemodynamic wave intensity parameters (except the reflection index) had strong correlations with age at the carotid artery. The mechanical properties and hemodynamic parameters of the femoral artery were not significantly age-dependent, but local wave speed, distensibility and forward wave intensity were significantly gender-dependent. The findings of the first and second studies contributed to the design of the third study. The carotid artery is an elastic artery relatively close to the heart and thus the hemodynamics of this vessel is related to left ventricular function. For this reason, the carotid hemodynamics of the same healthy population was investigated for the first time using the reservoir-wave approach. Pressure and velocity measurements were separated into their reservoir and excess components and the effects of age and gender on these parameters were studied. It was found that in the carotid artery reservoir and excess components are strongly affected by the ageing process. From the above studies some questions about the hemodynamics of central arteries remained unsolved. For this reason it was decided to carry out in vitro experiments in a mock circulatory system to investigate the effects of variation of compliance and stroke volume on the reservoir and excess pressure components of the ascending aorta. This allows for the study of different physiological and pathological conditions, such as age, hypertension, atherosclerosis and ventricular dysfunction in relation to vascular compliance and stroke volume. The reservoir and excess components of the measured pressure wave were both significantly related to aortic compliance and stroke volume, but the reservoir pressure had a stronger relationship with aortic compliance compared with the excess pressure and its magnitude increased more significantly when the aorta became stiffer. Wave speeds, calculated using measured and excess pressures, followed the same pattern, but the one calculated using excess pressure was smaller than the other. Wave speed was strongly related to aortic compliance, but not to the change of stroke volume. In conclusion, the use of the wave-only and the reservoir-wave models led to different values of wave speed and intensities that can be explained considering the anatomy of the arterial system. Notably, elastic and muscular arteries are differently affected by age and gender. The hemodynamics of the carotid artery are strongly related to age also in healthy subjects. Pressure and flow velocity in the carotid artery can be separated into their reservoir and excess components. The new non-invasive technique based on diameter and velocity measurements could be relevant in clinical practice as a screening tool.

Purposes: The purpose of this study was threefold. First, to examine how both the effectiveness of valsartan centric regimens and the patient-related factors affect the control rates of the Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP) and combined SBP/DBP; specifically for Belgian patients with a history of failed or intolerant anti-hypertensive treatment. Secondly, to assess the effectiveness of valsartan treatment groups and the related factors concerning a patients' total cardiovascular risk (TCVR) residuals. Lastly, to attempt to estimate the cost avoidance factor associated with taking varying levels of valsartan treatment doses. Methodology: This research took the form of a secondary-data analysis study, focusing on the analysis of data collected primarily from seven prospective studies conducted between 2004 and 2009, covering different regimens of valsartan. The variants of valsartan doses given to patients included: valsartan monotherapy (80mg or 160 mg); a combination of valsartan with hydrochlorothiazide (HCTZ) (80 mg and 12.5mg, 160mg and 12.5 mg, or 160mg and 25mg); and a combination of valsartan with amlodipine (80mg and 5mg, 160mg and 5mg, or 160mg and 10mg). We applied Bailey's approach, using Kaplan-Meier curves to estimate the distribution of treatment intensity at which the target rates of SBP, DBP and SBP/DBP were achieved. The treatment intensity was calculated by dividing the daily dose prescribed to a patient by the maximum daily recommended dose of that particular drug variant. The outcomes provided by Bailey's approach included the control rates of SBP, DBP and combined SBP/DBP, in addition to the reduction in TCVR residuals. Another aspect of our methodology was the use of a simulation method to estimate the cost avoidance by using valsartan treatment groups. We used OCED data to compare health indicators between the US and Belgium in order to estimate the ratio enabling us to calculate the cost of hypertension per patient per year. This cost was then used in the simulation method to calculate the cost avoidance of using varying levels of the treatment intensity of valsartan regimens. Results: A total of 17,683 patients were included in this study, contributed to by 3,434 physician-investigators. The mean age of the population was 63.63 + 11.83 years, with a mean BMI of 28.45 + 3.13 kg/m^2 and 47.7% of the population was male and the vast majority of the total population was Caucasian (98%). As a baseline the total population who had controlled SBP, DBP and combined SBP/DBP were 1358, 5301 and 1091 respectively. The total population who were categorized as low added risk TCVR, moderate added risk TCVR, high added risk TCVR, and very high added risk TCVR were 192; 3,721; 3,888 and 9,362 respectively. Overall, there was a statistically significant increase in the proportion of patients with controlled SBP, DBP and combined SBP/DBP after 90 days of starting on valsartan-centric regimens (p<0.001). Both older age and the presence of diabetes were associated with a lower control rate of SBP, DBP and combined SBP/DBP (P<0.05). High adherence to valsartan-centric regimens was associated with an increase in the control rates of blood pressure. Substantial reductions in total cardiovascular risk, particularly in the very high added-risk category was observed 5,852 times (33.1%) (P<0.001) and an increase in the low added risk TCVR 3,331 times (18.9%) (p<0.001). The associated cost avoidance with varying levels of treatment intensity were dose related. The cost avoidance associated with the treatment intensity levels of 0.25, 0.5, 0.75, 1.0 and 1.5 were $261,164; $2,403,188; $6,384,142; $8,702,272 and $10,230,321, respectively. Conclusion: The different levels of the treatment intensity of valsartan-centric regimens were effective in increasing the control rates of SBP, DBP and combined SBP/DBP in the real practice for patients whose prior treatment failed. Not only did valsartan regimens improve the BP control rate, they also reduced the TCVR residuals. Additionally, substantial cost avoidance was found to be associated with the use of higher levels of treatment intensity. These results may support the idea that intensive anti-hypertensive treatment may be associated with higher clinical and economic benefits for both patients and payers. However, more research might be needed to validate our results and to address the questions of adverse effects that may be associated with intensive anti-hypertensive therapy and the economic consequences of treating any such effects.

PURPOSE: To compare the effects of recovery intensity on performance of a bicycle sprint task and blood La⁻ clearance. METHODS: On three separate days twelve trained male subjects (27.4 ± 3.9 yrs) performed three supramaximal exercise (SE) bouts at 120% of maximum aerobic power (MAP) for 60% of the time to exhaustion (TTE). Bouts were separated by 5 mm of passive recovery (PR), active recovery (AR) or combined active recovery (CAR). The third bout was followed by a 14 mm recovery. Recovery intensities were: PR (rest), AR at 50% of the workload difference between the individual anaerobic threshold (IAT) and the individual ventilatory threshold (IVT) below the IVT ( ₋50%ΔT), or CAR at the IAT workload for 5 mm and at the ₋50%ΔT workload for 9 mm. Five 10 s sprints were performed 2 mm post-recovery. Blood lactate (La⁻) concentration, power parameters (Peak Power (PP), Mean Power (MP), Fatigue Index (Fl), and Total Work (TW)), Heart Rate (HR), and Oxygen Uptake (VO₂‚‚) were compared using repeated-measures ANOVA. Pairwise comparisons and dependent T-tests were performed to analyze differences. RESULTS: Mean La⁻ values for AR and CAR were lower than PR (9.7 ± 3.5, 9.5 + 3.5, 11.7 + 3.6, respectively, p≤0.05). La⁻ was significantly lower with CAR versus PR at the 3rd, 6th, 9th, and 14th mm of recovery (p≤0.05). AR versus PR La⁻ was lower at the 3rd, 6th, 9th, and 14th min of recovery (p≤0.05). Mean MP was greater in the AR group compared to the PR group (800.1 ± 114.5 vs 782.2 ± 111.7 W, p≤0.05). TW during AR was greater than PR (p≤0.05) but not CAR (p≤0.05, 40003.3 ± 5110.2, 39108.3 ± 4852.9, 39335.8 ± 5022.6 J, respectively). CONCLUSIONS: AR and CAR both demonstrated improved La⁻ clearance when compared to PR, but differences in La⁻ clearance did not determine performance on the sprint task. AR resulted in more TW than PR and greater maintenance of power over the sprints.