Hyperbolic Voronoi Percolation

In this thesis, we studied the behaviour of the critical probability for percolation of Voronoi cells in the hyperbolic plane. There are profound differences between this model of percolation in the hyperbolic plane and the Euclidean plane. Most notably, the critical probability is a function of the intensity

Cigarette Taxes and the Social Market

Previous researchers have argued that the social market for cigarettes insulates its participants from policies designed to curb youth smoking. Using state Youth Risk Behavior Survey data, we examine whether recent changes in state cigarette taxes affected how young smokers obtained their cigarettes. Our estimates suggest that tax increases reduce youth smoking participation primarily through their effect on third-party purchase, although there is evidence that they are negatively related to borrowing among younger teenagers and negatively related to direct purchase among older teenagers.youth smoking, cigarette taxes

Evaluation of Corn Condensed Distillers Solubles in Beef Cattle Diets and Grazing Double-Cropped Forages Following Corn Harvest

Corn condensed distillers solubles (CDS) is a protein and energy dense by-product from dry-milled production of ethanol. Recent oil extraction has posed modifications to the nutrient profile of CDS, suggesting that de-oiled CDS needs to be re-evaluated in beef cattle diets. Three experiments were conducted to evaluate the effects of CDS in high-concentrate diets, forage-based diets, as well as evaluate the effects of CDS on diet digestibility and rumen fermentation parameters in forage-based diets. Feeding CDS in high-concentrate diets up to 20% of the diet DM or in combination with wet distillers grains plus solubles (WDGS) improved performance and resulted in greater energy value compared to corn. Feeding values of 20% CDS or the combination of 16% CDS and 20% WDGS were 147 and 129% compared to corn, respectively. Feeding CDS in forage-based diets up to 40% of the diet DM diminished performance and resulted in a lesser energy value compared to corn. Linear decreases were observed in total tract digestibility of NDF and the acetate to propionate ratio in rumen fluid. Double-cropped forages following corn harvest offer livestock producers an opportunity to extend their grazing season on high quality forage in the fall. Additionally, crop producers may benefit from the implementation of grazing animals due to added soil nutrients and removal of residue. Therefore, an experiment was conducted to evaluate the effects of double-cropped oats following corn silage (CS) or high-moisture corn (HMC) on calf gains, forage production, and subsequent cash crop yields. Oats seeded after CS produced more forage biomass than oats seeded after HMC. Both treatments produced high quality oats (22% CP, 39% NDF, and 24% ADF averaged across treatments). Calf gains were greater grazing oats following CS compared to HMC at 1.10 and 0.84 kg / d, respectively. Across 1-yr of data, subsequent cash crop yields were not different for HMC and soybeans with increased CS yields in both covered/grazed and non-covered/non-grazed treatments compared to the covered/non-grazed treatment. Advisor: James C. MacDonal

Temperature and Polarization CMB Maps from Primordial non-Gaussianities of the Local Type

The forthcoming Planck experiment will provide high sensitivity polarization measurements that will allow us to further tighten the f_NL bounds from the temperature data. Monte Carlo simulations of non-Gaussian CMB maps have been used as a fundamental tool to characterize non-Gaussian signatures in the data, as they allow us to calibrate any statistical estimators and understand the effect of systematics, foregrounds and other contaminants. We describe an algorithm to generate high-angular resolution simulations of non-Gaussian CMB maps in temperature and polarization. We consider non-Gaussianities of the local type, for which the level of non-Gaussianity is defined by the dimensionless parameter, f_NL. We then apply the temperature and polarization fast cubic statistics recently developed by Yadav et al. to a set of non-Gaussian temperature and polarization simulations. We compare our results to theoretical expectations based on a Fisher matrix analysis, test the unbiasedness of the estimator, and study the dependence of the error bars on f_NL. All our results are in very good agreement with theoretical predictions, thus confirming the reliability of both the simulation algorithm and the fast cubic temperature and polarization estimator.Comment: 14 pages, 9 figures, revised version accepted by PRD, minor changes and acknowledgements adde

The critical probability for Voronoi percolation in the hyperbolic plane tends to 1/2

We consider percolation on the Voronoi tessellation generated by a homogeneous Poisson point process on the hyperbolic plane. We show that the critical probability for the existence of an infinite cluster tends to $1/2$ as the intensity of the Poisson process tends to infinity. This confirms a conjecture of Benjamini and Schramm.Comment: 15 pages, 6 figures, to be published in Random Structures and Algorithms, very minor corrections since the last versio

Poisson-Voronoi percolation in the hyperbolic plane with small intensities

We consider percolation on the Voronoi tessellation generated by a homogeneous Poisson point process on the hyperbolic plane. We show that the critical probability for the existence of an infinite cluster is asymptotically equal to $\pi \lambda/3$ as $\lambda\to0.$ This answers a question of Benjamini and Schramm.Comment: 70 pages, 11 figures, various corrections made compared to the last versio