Master of Science / Department of Human Nutrition / Kadri Koppel / Understanding the physiological activation and genetic variation of the sweet taste receptor (T1R) can improve formula optimization for products intended for a population of genetically diverse people. Computer modeling and cell culture techniques have thoroughly described the structure and binding sites of the T1R. The structure contains two subunits (T1R2 and T1R3) with multiple domains where sweet molecules can interact. The interaction takes place between individual molecules and amino acid residues of the T1R. The residues with which individual molecules interact differs between sweeteners. Person-to-person differences in the residue sequence of the T1R can arise from variation in the genes that encode the T1R (TAS1R), potentially effecting the function of the receptor. As a result of the specificity of binding interactions, genetic variation may affect sensitivity to some sweeteners, while sensitivity to other sweeteners remains normal. Therefore, it can be hypothesized that the level of person-to-person sweetness sensitivity variation may differ for each sweetener depending on the binding site of the molecule and site of T1R variation. The T1R structure, binding sites, and genetic variation will be reviewed, as well as potential parameters to predict the degree of sensitivity variation and formulation strategies to minimize the effects of sensitivity variation.

No description available.

The display of an Airy function via an optical image processing technique is demonstrated. Using a two-dimensional object with a cubic amplitude transmittance, one can observe a Fourier transformed image of which intensity variation is identical to that of the Airy function. A lens system is used to achieve the Fourier transformation of the object which is a two-dimensional binary filter. A set of computer simulations are performed prior to the optical experiments. Using the same method of optical display, the transient wave propagation in a dispersive medium is optically displayed based on the analogous relationship found between two equations: One is the Fourier form of a transient wave field propagating in a dispersive medium and the other is an equation of the diffraction pattern of an object constructed with two juxtaposed two-dimensional filters. A theoretical analysis is provided along with computer simulations. The use of a Spatial Light Modulator is proposed as the source of the input object in the optical experiment. / Master of Science

Deep soil mixing to construct stiff columns is one of the methods used today to improve performance of loose ground and remediate liquefaction problems. This research adopts a numerical approach to study seismic performance of soil-cement columnar reinforcements in loose sandy profiles. Different constitutive models were investigated in order to find a model that can properly predict soil behavior during seismic excitations. These models included NorSand, Dafalias-Manzari, Plasticity Model for Sands (PM4Sand) and Pressure-Dependent-Multi-Yield-02 (PDMY02) model. They were employed to predict behavior of soils with different relative densities and under different confining pressures during monotonic and cyclic loading. PDMY02 was identified as the most suitable model to represent soil seismic behavior for the system studied herein. The numerical aspects of the finite element approach were investigated to minimize the unintended numerical miscalculations. The focus was put on convergence tolerance, solver time-step, constraint definition, and, integration, material and Rayleigh damping. This resulted in forming a robust numerical configuration for 3-D nonlinear models that were later used for studying behavior of the reinforced grounds. Nonlinear finite element models were developed to capture the seismic response of columnar reinforced ground during dynamic centrifuge testing. The models were calibrated with results from tests with unreinforced profiles. Thereafter, they were implemented to predict the response of two reinforced profiles during seismic excitations with different intensities and liquefaction triggering. Model predictions were compared with recordings and the possible effects from the reinforcements were discussed. Finally, parametric studies were performed to further evaluate the efficiency of the reinforcements with different extension depths and area replacement ratios. The results collectively showed that the stiff elements, if constructed appropriately, can withstand seismic excitations with different intensities, and provide a firm base for overlying structures. However, the presence of the stiff elements within the loose ground resulted in stronger seismic intensities on the soil surface. The columns were not able to considerably reduce pore water pressure generation, nor prevent liquefaction triggering. The reinforced profiles, comparing to the free-field profiles, had larger settlements on the soil surface but smaller settlements on the columns. The results concluded that utilization of the columnar reinforcements requires great attention as these reinforcements may result in larger seismic intensities at the ground surface, while not considerably reducing the ground deformations. / Ph. D.