Title: Biomechanical response of the knee meniscus to the axial loads Work Title: The quantification of the structural changes in deep layer of the knee meniscus using the standardized axial loading Purpose: Due to the internal structure of the knee joint, the ability to characterize and quantify the dynamic response of the meniscal tissue directly in vivo is highly problematic. The main purpose of this study was to investigate the behavior of the meniscus under loading conditions, using parametric MR imaging. Methods: Subjects with no history of knee pain or meniscal problems were included in the study (mean age 27.8 ± 1.3 years). To obtain values of relaxation times T2* in the meniscus, the vTE sequence was used with 10 echoes ranging from 0.8 to 10.1 ms. This has resulted in minimizing the echo time, which is an advantage when differentiating meniscal tissue from surrounding components. First of all, an unloaded limb was scanned and immediately after, the limb loaded half of the person's weight was measured repeatedly in 4 consecutive scans. A custom - made diamagnetic apparatus was developed to simulate stress conditions on the lower limb in a conventional MR scanner. At each 6:10 min measurement, the knee joint was scanned in 64 sections, each image displaying a 1.3 mm section.The two -...

Investigating past changes in Earth's climate can provide useful information for assessing future climate change scenarios. Planktic foraminifera preserved in marine sediment are commonly used as a tool to reconstruct past environmental change. Here I present a combination of modern census and multinet data from the North Pacific, a new compilation of global census data, a new global calibration for Mg/Ca ratios in Neogloboquadrina pachyderma, and foraminifera assemblage, trace element, and boron isotope data from the North Pacific spanning the last deglaciation. New modern census data from the North Pacific shows that two key sub-polar proxy carrying species, N. pachyderma and Globigerina bulloides, predominantly live between 0-50 m in the water column. Global planktic foraminifera diversity is observed to be driven primarily by sea surface temperature, with upwelling and ocean productivity providing key secondary roles. In the North Pacific, a preservation bias of N. pachyderma over G. bulloides is observed when comparing multinet and core-top samples, highlighting the importance of tracking dissolution during downcore studies. To improve the use of Mg/Ca ratios in N. pachyderma downcore, I produced a new global calibration with a temperature sensitivity of 6 % per °C. This calibration was combined with boron isotope and Mg/Ca data from sediment core MD02-2489 to investigate changes in North Pacific circulation, productivity, and CO₂ during the last deglaciation. Two intervals of high surface CO₂ were observed, the first during Heinrich Stadial 1, where deep ventilation mixed CO₂ and nutrients throughout the water column. The second occurred during the Bølling-Allerød, where stratification pooled nutrients and CO₂ in surface waters, leading to enhanced productivity and CO₂ outgassing. Overall, this thesis improves the use of planktic foraminifera as tools for investigating past climate change and highlights the role of the North Pacific in deglacial CO₂ release.

Accurate measurement of turbine engine compressor inlet total temperature is paramount for controlling engine speed and pressure ratio. Various methods exist for measuring compressor inlet total temperature on turbojet engines with hydromechanical control. One method involves the use of an ejector-diffuser system (eductor) to pull air from the engine inlet in order to measure the incoming total temperature. Analysis of historical test data has revealed that the inlet temperature measurement can be biased at certain flight conditions causing engine mis-scheduling and off-nominal engine operation. This bias is characterized primarily by adverse heat transfer effects and secondly by poor flow quality in the eductor tubing. Alternate eductor system configurations have been proposed to mitigate temperature bias. A one-dimensional engineering model of the eductor system was developed to facilitate the analysis of baseline and alternate eductor configurations. The model is calibrated with results from Computational Fluid Dynamics and validated with ground test data. The validated model is used to quantify the performance of several eductor configurations throughout the range of expected operating conditions and to quantify the amount of compressor inlet temperature measurement bias mitigation each configuration provides.

Determining the distribution of porosity and permeability is one of the main challenges in carbonate petroleum reservoir characterization and requires a thorough understanding of pore type and origin, as well as their spatial distributions. Conventional studies of carbonate reservoirs require interpretation and analysis of cores to understand porosity. This study investigates the use of NMR logs in the determination of pore type and origin. This study is based on the analysis of both thin section petrographic and NMR data from a single well that cored the Lower Cretaceous (Aptian) shelf carbonates belonging to the Shuaiba Formation of the Middle East. Photographs of thin sections were used to determine pore type and origin according to Ahr's genetic classification of carbonate porosity. Descriptive statistics and modeling were used to analyze the NMR T2relaxation time distributions. Descriptive statistical analyses included estimating arithmetic average, standard deviation, skewness, median, mode and 90th percentile. T2modeling was performed by fitting multiple log-normal distributions to the measured T2distribution. Data from thin section petrography and from NMR measurements were then compared using conditional probabilities. As expected, thin section analysis revealed the predominance of mud-supported fabrics and micropores between matrix grains Vugs and dissolved rudistid fragments account for most of the macro porosity. Descriptive statistics showed that the mode and th percentile of the T2distribution had the greatest power to discriminate pores by origin. The first principal component (PC1) of the mode-90th percentile system was then used to compute the probabilities of having each pore origin, knowing that PC1 belongs to a given interval. Results were good, with each origin being predictable within a certain range of PC1. Decomposition of the T2distributions was performed using up to 3 log-normal component distributions. Samples of different pore origin behaved distinctively. Depositional porosity showed no increase in fit quality with increasing number of distributions whereas facies selective and diagenetic porosity did, with diagenetic porosity showing the greatest increase.

No description available.

No description available.

Determining the distribution of porosity and permeability is one of the main challenges in carbonate petroleum reservoir characterization and requires a thorough understanding of pore type and origin, as well as their spatial distributions. Conventional studies of carbonate reservoirs require interpretation and analysis of cores to understand porosity. This study investigates the use of NMR logs in the determination of pore type and origin. This study is based on the analysis of both thin section petrographic and NMR data from a single well that cored the Lower Cretaceous (Aptian) shelf carbonates belonging to the Shuaiba Formation of the Middle East. Photographs of thin sections were used to determine pore type and origin according to Ahr's genetic classification of carbonate porosity. Descriptive statistics and modeling were used to analyze the NMR T2relaxation time distributions. Descriptive statistical analyses included estimating arithmetic average, standard deviation, skewness, median, mode and 90th percentile. T2modeling was performed by fitting multiple log-normal distributions to the measured T2distribution. Data from thin section petrography and from NMR measurements were then compared using conditional probabilities. As expected, thin section analysis revealed the predominance of mud-supported fabrics and micropores between matrix grains Vugs and dissolved rudistid fragments account for most of the macro porosity. Descriptive statistics showed that the mode and th percentile of the T2distribution had the greatest power to discriminate pores by origin. The first principal component (PC1) of the mode-90th percentile system was then used to compute the probabilities of having each pore origin, knowing that PC1 belongs to a given interval. Results were good, with each origin being predictable within a certain range of PC1. Decomposition of the T2distributions was performed using up to 3 log-normal component distributions. Samples of different pore origin behaved distinctively. Depositional porosity showed no increase in fit quality with increasing number of distributions whereas facies selective and diagenetic porosity did, with diagenetic porosity showing the greatest increase.

No description available.

Solid-state NMR spectroscopy was used to site-specifically investigate the protein-water interface of a seven alpha-helical transmembrane protein, Anabaena sensory rhodopsin (ASR). Water-edited experiments, which employ a T2-filter to select for mobile protons, provided a means to detect residues which appear to be in close contact to water molecules, and to gain insights about the water-protein interface of ASR. First, through the application of Lee-Goldburg homonuclear decoupling, it was determined that polarization transfer across this interface is dominated by through-space interaction mechanisms, as opposed to chemical exchange. A series of two-dimensional experiments were also performed to detect polarization transfer along the backbone and to the sidechains of the protein. Residues located in solvent-accessible regions of the protein, such as the B-C loop, were found to obtain polarization quickly, as expected, and in agreement with previous H/D exchange data. Residues known to be in contact with bound crystal water molecules were also detected. In addition to these, we found new residues which appear to be in contact with water, indicating additional HN-H2O interactions, or additional contacts with bound water molecules. Most of these residues were located beside exchangeable regions of ASR. Sidechains of residues located in the cytoplasmic side of helix F were seen to be in close contact with mobile water molecules, supporting evidence of a hydrophilic chain along the cytoplasmic half of the protein, which is suggested to cause a functional outward tilt of the cytoplasmic half of helix F upon light-activation.

In this thesis, three different types of polymer-based gels are fabricated and characterized for passive and active applications. Silica aerogel is a 3D mesoporous solid material that can be used for thermal insulation or in the biomedical industry. In this thesis, silica aerogel is cross- linked with diisocyanate to improve its strength and flexibility, which greatly opens up the range of applications. Then, soft polymer gel with tissue equivalent characteristics is fabricated to mimic the spin-lattice (T1) and spin-spin (T2) relaxation times for the magnetic resonance imaging (MRI) phantom of a liver with lesions. This study demonstrates a relationship between the composition of a gelling agent, and T1 and T2 modifiers on its dielectric, mechanical and imaging properties. Finally, an ionic electroactive polymer (EAP) that can be actuated on an electric field is fabricated, and its swelling and bending behaviours on design parameters are closely examined.