Global ETD Search

11	Optical Scattering Properties of Fat Emulsions Determined by Diffuse Reflectance Spectroscopy and Monte Carlo Simulations Hussain, Moeed January 2010 (has links) To estimate the propagation of light in tissue-like optical phantoms (fat emulsions), this thesis utilized the diffuse reflectance spectroscopy in combination with Monte Carlo simulations. A method for determining the two-parametric Gegenbauer-kernal phase function was utilized in order to accurately describe the diffuse reflectance from poly-dispersive scattering optical phantoms with small source-detector separations. The method includes the spectral collimated transmission, spatially resolved diffuse reflectance spectra (SRDR) and the inverse technique of matching spectra from Monte Carlo simulations to those measured. An absolute calibration method using polystyrene micro-spheres was utilized to estimate the relation between simulated and measured SRDR intensities. The phase function parameters were comparable with previous studies and were able to model measured spectra with good accuracy. Significant differences between the phase functions for homogenized milk and the nutritive fat emulsions were found. Scattering properties fat emulsions optical phantoms Diffuse Reflectance Spectroscopy Monte Carlo Simulations Reverse Monte carlo method Clinoleic Vasolipid Intralipid phase function. NATURAL SCIENCES NATURVETENSKAP
12	Ab initio Structure Inversion for Amorphous Materials Bhattarai, Bishal January 2018 (has links) No description available. Condensed Matter Physics Materials Science Physics Quantum Physics amorphous materials reverse monte carlo structure inversion realistic inversion density functional theory phonon specific heat force enhanced atomic refinement
13	The Mixed Glass Former Effect- Modeling of the Structure and Ionic Hopping Transport Schuch, Michael 11 October 2013 (has links) The origin of the Mixed Glass Former Effect (MGFE) is studied, which manifests itself in a non-monotonic behavior of the activation energy for long-range ion transport as a function of the mixing ratio of two glass formers. Two theoretical models are developed, the mixed barrier model and the network unit trap model, which consider different possible mechanisms for the occurrence of the MGFE. The mixed barrier model is based on the assumption that energy barriers are reduced for ionic jumps in regions of mixed composition. By employing percolation theory it is shown that this mechanism can successfully account for the behavior of the activation energy in various ion conducting mixed glass former glasses. The network unit trap model is based on the fact that a variety of network forming units, the so-called Q(n) species, can be associated with one glass former. Using a thermodynamic approach, the change of the concentration of these units in dependence of ionic concentration and the glass former mixing ratio is successfully predicted for alkali borate, phosphate and borophosphate glasses. In a second step, the charge distribution of the various units is considered and related to it, the binding energies to alkali ions. This gives rise to a modeling of the ionic transport in an energy landscape that changes in a defined manner with the glass former mixing ratio. Kinetic Monte Carlo simulations for alkali borophosphate glasses, which serve as a representative system for the MGFE in the literature, demonstrate that this approach succeeds to predict the behavior of the activation energy. In a further part of the thesis, Reverse Monte Carlo (RMC) simulations for the atomic structure of sodium borophosphate glasses are carried out with X-ray and neutron diffraction data as further input from experiments. Three-dimensional structures could be successfully generated that are in agreement with all experimental and theoretical constraints. Volume fractions of the ionic conduction pathways determined from these structures, however, do not show a substantial relationship to the activation energy, as earlier proposed in the iterature for alkali borate and alkali phosphate glasses. Ionentransport Gläser Ion tranport glasses hopping Reverse Monte Carlo 33.10 - Theoretische Physik: Allgemeines 35.90 - Festkörperchemie 33.66 - Amorpher Zustand, Gläser ddc:530 ddc:540
14	Bioengineered Metal Nanoparticles: Shape Control, Structure, and Catalytic Functionality Ramezani-Dakhel, Hadi 26 May 2015 (has links) No description available. Biochemistry Chemistry Condensed Matter Physics Molecules Nanotechnology metal nanoparticles platinum palladium peptide simulation molecular dynamics shape catalysis structure tetrahedron nanoparticles cubic nanoparticles single twinned nanoparticles pair distribution function reverse Monte Carlo simulation
15	Computational analysis of wide-angle light scattering from single cells Pilarski, Patrick Michael 11 1900 (has links) The analysis of wide-angle cellular light scattering patterns is a challenging problem. Small changes to the organization, orientation, shape, and optical properties of scatterers and scattering populations can significantly alter their complex two-dimensional scattering signatures. Because of this, it is difficult to find methods that can identify medically relevant cellular properties while remaining robust to experimental noise and sample-to-sample differences. It is an important problem. Recent work has shown that changes to the internal structure of cells---specifically, the distribution and aggregation of organelles---can indicate the progression of a number of common disorders, ranging from cancer to neurodegenerative disease, and can also predict a patient's response to treatments like chemotherapy. However, there is no direct analytical solution to the inverse wide-angle cellular light scattering problem, and available simulation and interpretation methods either rely on restrictive cell models, or are too computationally demanding for routine use. This dissertation addresses these challenges from a computational vantage point. First, it explores the theoretical limits and optical basis for wide-angle scattering pattern analysis. The result is a rapid new simulation method to generate realistic organelle scattering patterns without the need for computationally challenging or restrictive routines. Pattern analysis, image segmentation, machine learning, and iterative pattern classification methods are then used to identify novel relationships between wide-angle scattering patterns and the distribution of organelles (in this case mitochondria) within a cell. Importantly, this work shows that by parameterizing a scattering image it is possible to extract vital information about cell structure while remaining robust to changes in organelle concentration, effective size, and random placement. The result is a powerful collection of methods to simulate and interpret experimental light scattering signatures. This gives new insight into the theoretical basis for wide-angle cellular light scattering, and facilitates advances in real-time patient care, cell structure prediction, and cell morphology research. light scattering computational analysis pattern analysis pattern recognition cytometry machine learning image processing image analysis single cells optics medical diagnostics lab on a chip wide-angle light scattering shape recognition biomedical image analysis fourier theory fourier transform cellular optics optical simulation scattering simulation inverse scattering problem inverse analysis computational intelligence mitochondria cell morphology cancer scattering theory iterative methods generate and test reverse monte carlo image parameterization structure prediction 3D structure prediction computer science computer engineering electrical engineering
16	Computational analysis of wide-angle light scattering from single cells Pilarski, Patrick Michael Unknown Date No description available. light scattering computational analysis pattern analysis pattern recognition cytometry machine learning image processing image analysis single cells optics medical diagnostics lab on a chip wide-angle light scattering shape recognition biomedical image analysis fourier theory fourier transform cellular optics optical simulation scattering simulation inverse scattering problem inverse analysis computational intelligence mitochondria cell morphology cancer scattering theory iterative methods generate and test reverse monte carlo image parameterization structure prediction 3D structure prediction computer science computer engineering electrical engineering

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