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RISS 인기검색어
- 검색키워드
- 저자 : Wilmer, Jeremy Bennet (검색결과 10 건)
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Wilmer, Jeremy Bennet Harvard University 2006 해외박사(DDOD)
The study of individual differences in vision has much to offer both basic science and the science of group differences. For example, research on individual differences in color vision has taught us about basic functional mechanisms and their underlying genetics while also informing us about color blindness and its differing prevalence between males and females. Despite such utility, individual differences in vision are rarely studied. This dissertation seeks to demonstrate by example the value, to both basic science and the science of differences between groups, of studying individual differences in vision. In paper one, we show evidence for two independent visual motion processing deficits in developmental dyslexia, each associated with a different reading deficit. A consideration of individual differences in this study allows us to establish that these deficits are independent, while providing evidence that our two motion processing measures may rely upon independently varying processes in normal populations as well. In paper two, we report independent associations between individual differences in two types of motion processing and two periods of oculomotor pursuit. There is a clear transition between these two associations at the time of the initial saccade, evidence that the motion signals driving presaccadic pursuit differ from those driving postsaccadic pursuit. This study both informs us about the nature of signals driving smooth pursuit and provides a useful point of departure for clinical investigations involving smooth pursuit. In paper three, we demonstrate a sex difference favoring males in precision of smooth pursuit eye movements, which could underlie male advantages seen in gross visuomotor performance. This sex difference is independent of the associations reported in paper two, and we show evidence that the difference is likely to be one of internal monitoring of eye movement commands, or efference copy. Given extensive knowledge of factors that differentially affect development of men and women, the further investigation of this sex difference could aid our understanding of the development of oculomotor function. We propose that a healthy science of individual differences in vision could lead to insights applicable to both basic science and the science of group differences.
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WILMER, ELIZABETH LEE HARVARD UNIVERSITY 1999 해외박사(DDOD)
We describe the behavior of certain families of Markov chains as they approach their stationary distributions. Prior methods do not work well for these chains, which are non-reversible, have non-uniform stationary distributions, have little symmetry, and are nearly periodic. Only a few families have been analyzed as precisely as we achieve for these chains, which can now serve as test cases for more general bounds. Using a central limit theorem and large deviation bounds to approximate combinatorial expressions for the higher-order transitions of these chains yields local limit theorems. From these we obtain the exact asymptotics of convergence to stationarity, as measured in total variation and related metrics. The time to be near stationarity depends on the number of non-deterministic transitions; in our examples, it ranges from <italic> O</italic>(<italic>n</italic><super>2</super>) to <italic>O</italic>(<italic> n</italic><super>3</super>), where <italic>n</italic> is the size of the state space. These families of chains converge to stationarity gradually; they do not exhibit cut-offs. Our local limit theorems also imply that appropriately scaled embeddings of these chains into <math> <f> <blkbd>R</blkbd></f> </math>/<math> <f> <blkbd>Z</blkbd></f> </math> have finite dimensional distributions approaching those of Brownian motion on <math> <f> <blkbd>R</blkbd></f> </math>/<math> <f> <blkbd>Z</blkbd></f> </math>. We compare our results with bounds from symmetrization and Nash inequalities in a special case. We also describe the asymptotic behavior of the spectrum of a particular family of chains.
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Petroleum filling history of central Alaskan North Slope fields
Masterson, Wilmer Dallam, IV The University of Texas at Dallas 2001 해외박사(DDOD)
The petroleum filling history of the central Alaskan North Slope was reconstructed with burial history models that were calibrated with source rock and oil geochemistry in the area surrounding the Prudhoe Bay, Kuparuk, West Sak, Pt. McIntyre, Tam, and Alpine Fields. Prudhoe Bay and Kuparuk are the two largest currently producing oil fields in the United States. Oil in the Prudhoe Bay Field is interpreted as a mixture co-sourced from three source rocks: Upper Triassic marine carbonate, shale, and phosphorite (Shublik Formation), Lower Cretaceous marine shale (HRZ Formation), and Lower Jurassic marine shale (Kingak Shale). The total expelled oil volume within the Prudhoe Bay Field fetch area of 4,000 square miles is modeled to be 168 billion barrels and consists of 59% Shublik, 28% HRZ, and 13% Kingak source rock contribution. The carbon isotopic composition, API gravity, and sulfur content of the Prudhoe Bay main field oil accumulation closely match the modeled off composition in the Prudhoe Bay fetch area. The estimated 40 to 50 billion barrels of original oil in place in the Prudhoe Bay and West Sak Fields imply a Prudhoe Bay fetch area migration efficiency of 25 to 30%. Spillage of Prudhoe oil into the West Sak Field occurred during post-Eocene uplift and 1–2 degrees of eastward tilting that decreased the hydrocarbon column at Prudhoe Bay Field from 2400 to 1000 feet and created the structural trap at the Prudhoe Bay West End. The Prudhoe Bay main field tar mat formed when gas deasphalted the oil column in Tertiary time, and carbonates in the Carboniferous Lisburne Formation are interpreted as the source of most of the carbon dioxide in the Prudhoe Bay gas cap. Kuparuk Field oils were predominantly sourced from Shublik source rock. The HRZ Formation is interpreted as the primary source for Tarn Field oils and the Kingak Shale is interpreted as the primary source for Alpine Field oils. The West Sak Field accumulation is interpreted as a mixture of moderately biodegraded oil that spilled from the Prudhoe Bay Field and lightly biodegraded gas/condensate that leaked from the underlying Kuparuk Field.
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Henao, Wilmer ProQuest Dissertations & Theses University of Mich 2019 해외박사(DDOD)
Radiation therapy treatments for cancer aim to deliver a toxic dose of radiation to malignant tumors, while controlling the dose to healthy tissues and organs. In external beam therapy, radiation is delivered by a linear accelerator, and a Multileaf Collimator (MLC) is used to change the shape of the beam opening, or aperture. A treatment plan for each patient is designed by specifying the apertures and timing and source intensity decisions for each beam angle used in the treatment. Mathematical optimization models are commonly used in modern radiation treatment planning, and rely on mathematical models of the dose distribution delivered to the patient by the portions of the beams exposed by the apertures.Volumetric Modulated Arc Therapy (VMAT) and Tomotherapy are two of the highly utilized forms of external-beam radiation therapy, each with unique features of the MLCs. For both modalities, the current standard treatment planning methodology is prone to creating a discrepancy between the doses that are intended, and the doses that are actually delivered to the patient. The goal of our research is to develop improved treatment planning strategies that reduce this divergence.In tomotherapy, the MLC consists of binary leaves alternating between fully open and closed states, while the beam traces a helicoidal trajectory around the patient. Dosimetric discrepancies in tomotherapy have been attributed to the lack of accurate models of leaf motion and dose delivery during leaf transitions between states, with their impact exacerbated by short leaf open times (LOTs). Moreover, the discretization of beam motion currently used for dose calculations is relatively coarse, which also contributes to the dosimetric errors. We propose a new treatment planning delivery and modeling paradigm for tomotherapy that allows us to impose lower bounds on minimum and average LOTs, while allowing for arbitrarily finer discretization of beam motion --- both features absent from existing approaches.VMAT treatments use a rectangular MLC, with leaves that can open and close partially, creating complex two-dimensional aperture shapes, while the beam moves along pre-specified trajectories, or arcs. Current VMAT treatment planning approaches tend to create plans with complex and irregular apertures with small areas and excessive edge lengths. The dose delivery models for such apertures are less accurate than for apertures with simpler, rounder shapes; therefore discrepancies between planned and delivered dose are frequently observed in VMAT treatments as well. Our proposed optimization model for VMAT treatment planning considers a tradeoff between the quality of the planned treatment with respect to the clinical goals and a penalty on irregularly-shaped apertures. This model extends and combines a VMAT planning model with a new edge metric penalty with favorable mathematical properties compared to penalties studied in the literature. Due to the complexities of VMAT delivery, the resulting optimization models require development of heuristic solution approaches. We develop a significant extension of a heuristic algorithm for VMAT treatment planning applicable to the new model.We test the models and algorithms proposed in this thesis on clinical cases, demonstrating improvements in treatment characteristics of the resulting treatment plans --- LOTs and discretization levels in tomotherapy and aperture shape metrics in VMAT. While the precise reductions in dosimetric discrepancies resulting from these changes will need to be confirmed by dosimetric studies, these favorable characteristics should lead to clinical treatments that are more effective and safer for the patients.
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Scherder, Curtis Wilmer Iowa State University 2008 해외박사(DDOD)
Soybean [Glycine max (L.) Merr.] lines with increased levels of oleate content may be useful for the food industry. Iowa State University has used the mutant soybean line, M23, developed by Saga University in Japan, to develop lines that contain mid-oleate content combined with 10 g kg -1 linolenate (MO/LLN), low saturated fatty acids (MO/LS), and both low saturated fatty acids and 10 g kg-1 linolenate (MO/LS/LLN). The first objective of the research was to determine the stability of oleate content across four Iowa environments and one Missouri environment in two years for the three types of lines. For environmental stability based on either the evaluation of the range of oleate content over the environments or a regression on an environmental index, the MO/LLN lines on average were the most stable followed by the MO/LS/LLN lines and the MO/LS lines. When stability was based on the frequency with which a line would exceed 500 g kg-1 oleate, the lines with the highest mean oleate in each type had the greatest stability. The second objective of this research was to determine the effect of the ol allele that controls increased oleate content in M23 on agronomic and seed characteristics. The performance of 27 MO/LLN lines from each of three populations was compared to that of 27 lines with conventional oleate content (CO/LLN) from the same population. The MO/LLN lines had 12% lower yield on average than the CO/LLN lines. For the other traits, many of the MO/LLN lines were comparable to the CO/LLN lines indicating that it would be possible to develop MO/LLN cultivars with similar agronomic and seed characteristics as CO/LLN cultivars. The third objective of this research was to evaluate a mutated population of soybean for polymorphisms in the FAD2-1B gene. A total of 1452 M2 families were screened and 32 M2 families were selected that could potentially have changes in the FAD2-1B gene. When M3 progeny from the 32 families were evaluated in the field, none of them had elevated oleate content and they had the same sequence for the FAD2-1B gene as Williams 82, the wild-type progenitor.
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Pacheco Dominguez, Wilmer Javier North Carolina State University 2014 해외박사(DDOD)
Distillers dried grains with solubles (DDGS) is the co-product that remains after fermenting the starch fraction of grains to produce ethanol. Previous research studies have shown that the main limitations for using DDGS in poultry and swine diets were reduced pellet quality and increased nutrient variability. Our working hypothesis was that further grinding of DDGS would improve pellet quality and live performance in poultry and swine and that the optimum dietary inclusion would depend upon feed formulation strategies. The first study (Chapter 2) was designed to evaluate the effect of inclusion level and particle size of DDGS as well as soybean meal (SBM) particle size on pellet durability index (PDI). Diets containing DDGS exhibited improved (P≤0.05) PDI relative to diets without DDGS. Further grinding of SBM in diets with DDGS also improved (P≤0.05) PDI. Adding 30% DDGS to corn-soy diets improved PDI and further grinding of SBM, but not DDGS, improved pellet quality. The second study (Chapter 3) evaluated the effect of particle size and DDGS inclusion on pellet quality and live performance of broilers fed diets formulated on a digestible amino acid (AA) basis. Birds fed diets with fine DDGS consumed more feed (P≤0.05) and exhibited greater BW (P≤0.05) at 42 d than birds fed diets with coarse DDGS with no difference in feed efficiency. Birds fed pelleted diets with fines removed exhibited greater BW at 35 and 42 d than birds fed pelleted diets with 50% fines. Birds fed diets containing 30% DDGS consumed more feed ( P≤0.05) but exhibited poorer feed efficiency (P≤0.05) at 42 d than birds fed 15% DDGS with no differences in BW. The results observed on this experiment demonstrated that broilers exhibited improved live performance when fed finely ground DDGS (482 mum) with no fines in the feed and that up to 30% DDGS could be fed when diets were formulated on a digestible AA basis. The third study (Chapter 4) evaluated the effect of dietary DDGS inclusion and the method of crude fat analysis on pellet quality, nutrient digestibility, incidence of footpad lesions, and broiler live performance in diets formulated on a total AA basis. Increasing dietary inclusion of DDGS to 30% reduced pellet quality, BW, and protein digestibility as well as increased footpad lesions. Feed efficiency was also poorer. Evidently, broilers can be fed up to 15% DDGS in diets formulated on total AA basis while the method of estimating crude fat had a marginal effect on live performance. The final experiment (Chapter 5) evaluated the effect of DDGS particle size and percentage fines on grower-finisher pig performance. Particle size of DDGS and percentage fines in the feed did not impact (P≤0.05) daily gain, daily feed intake, or feed efficiency. It was determined that the particle size of DDGS did not improve overall live performance so DDGS did not need to be further ground upon receipt at the feed mill. In addition, up to 25% pellet fines could be fed without affecting grower-finisher pig performance. Based on the results of these 4 studies, it was concluded that: (1) further grinding DDGS did not influence pellet quality and grower-finisher pig live performance; (2) grinding SBM improved pellet quality; (3) feed containing up to 25% fines could be fed to broilers or grower-finisher pigs without adverse effects on live performance; (4) and use of digestible AA values during feed formulation allowed for higher DDGS inclusion.
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