The current study addresses the stability of shock waves propagating through dissipative media, analogous to both granular media and molecular gases undergoing endothermic reactions. In order to investigate the stability, a simple molecular dynamics model was developed to observe shock waves and their structures with the inclusion of energy dissipation. For this, an Event Driven Molecular Dynamics model was implemented in a 2D environment, where a molecule is represented by a disk. The simulations addressed the formation of a shock wave in a gas by the sudden acceleration of a piston. Inelastic collisions were assumed to occur only if an impact velocity threshold is surpassed, representing the activation energy of the dissipative reactions. Parametric studies were conducted for this molecular model, by varying the strength of the shock wave, the activation threshold and the degree of inelasticity in the collisions. The resulting simulations showed that a shock structure does indeed become unstable with the presence of dissipative collisions. This instability manifests itself in the form of distinctive high density non-uniformities behind the shock wave, which take the form of convective rolls. The spacing and size of this ``finger-like" unstable pattern was shown to be dependent on the degree of inelasticity, the activation energy, and the strength of the driving piston. The mechanism responsible for the instability was addressed by studying the time evolution of the material undergoing the shock wave compression and further relaxation. It is found that the gas develops the instability on the same time scales as the clustering instability in homogeneous gases, first observed by Goldhirsch and Zanetti in granular gases. This confirmed that the clustering instability is the dominant mechanism.

Neurologically normal individuals show a leftward spatial bias and tend to collide with objects on the right side more frequently than on the left. The upper visual field is associated with extrapersonal space, and mediated by the ventral stream through parvocellular projections. The lower visual field is associated with peripersonal space, and mediated by the dorsal stream through magnocellular projections. Upper and lower visual field differences have been observed in perceptual asymmetries but results have been mixed. Object- and space-based coordinates also both influence the leftward bias; however their relative contributions are unknown as similar spatial conditions are often collapsed across. More left-side collisions emerged on a route following task in the lower visual field and more right-side collisions were seen in the upper visual field (Thomas, Stuckel, Gutwin, & Elias, 2009). Left-handers made more right-side collisions in the central condition, whereas right-handers showed no bias. Leftward biases on the greyscales task were stronger in the lower visual field; however no distance-based differences were observed (Thomas & Elias, 2010). A stronger spatial bias was found on the greyscales task, whereas a stronger object-based bias was found on the object luminosity task (Thomas & Elias, in press). When individual spatial conditions were examined, the image chosen most often was always located in the lower field. Stimulus type and spatial location interacted to determine which coordinate type contributes more strongly to leftward biases. We also found that the leftward bias on the greyscales task was stronger in the lower visual field during prolonged presentation and in the upper visual field during brief presentation. A global motion task was created to preferentially engage magnocellular projections to the dorsal stream. Isoluminant red/green and blue/yellow colour tasks, which preferentially engage parvocellular projections to the ventral stream, were also created. Leftward biases were seen on the greyscales and motion tasks. On an isoluminant colour task, biases were significantly weakened, suggesting leftward biases exhibited by neurologically normal people are mediated by magnocellular projections to the dorsal stream and this preferential processing leads to a lower visual field advantage on the greyscales task.

A measurement of J/\Psi polarization has been performed for 200 GeV proton+proton collisions with the PHENIX Muon Arms at RHIC. The results from the current data show no polarization within the PHENIX acceptance range. The results are consistent with the current model predictions and other experimental measurements.

It has been well established in previous research that driving during rainfall is associated with increased risk of traffic collision involvement. Of particular concern are heavy rain events, which result in elevated risks up to three times higher than those for light rainfalls. As the global climate changes in the coming century, altered precipitation patterns are likely. The primary objective of this thesis is to estimate the potential impacts of climate change on traffic safety in two large Canadian urban regions: the Greater Toronto Area and Greater Vancouver. A secondary objective is to provide a framework or methodology for exploring this question. In accomplishing the primary objective, daily collision and climate records are utilized to establish an empirical estimate of present-day rainfall-related crash risk. This estimate is combined with results of a climate modelling exercise to arrive at a possible traffic safety future for urban Canada over the next 40 years. For the second objective, several important decisions related to data acquisition, compatibility, and completeness are considered, and the tradeoffs are mapped out and discussed, in order to provide guidance for future studies. Results indicate that over the next 40 years, Toronto is likely to see a mean annual increase in rain days of all intensities, resulting in marginally more collisions and casualties each year. Substantially more rainfall days are projected for Vancouver by mid-century, resulting in a small increase in annual incident counts. In both study regions, the greatest adverse safety impact is likely to be associated with moderate to heavy rainfall days (≥ 10 mm); this estimate is consistent with the greater risk increases associated with these conditions today, and suggests that attention should be paid to future changes in the frequency and intensity of extreme rainfall events. Indeed, heavy rain days are likely to account for approximately half of all additional collision and casualty incidents.

Neurologically normal individuals show a leftward spatial bias and tend to collide with objects on the right side more frequently than on the left. The upper visual field is associated with extrapersonal space, and mediated by the ventral stream through parvocellular projections. The lower visual field is associated with peripersonal space, and mediated by the dorsal stream through magnocellular projections. Upper and lower visual field differences have been observed in perceptual asymmetries but results have been mixed. Object- and space-based coordinates also both influence the leftward bias; however their relative contributions are unknown as similar spatial conditions are often collapsed across. More left-side collisions emerged on a route following task in the lower visual field and more right-side collisions were seen in the upper visual field (Thomas, Stuckel, Gutwin, & Elias, 2009). Left-handers made more right-side collisions in the central condition, whereas right-handers showed no bias. Leftward biases on the greyscales task were stronger in the lower visual field; however no distance-based differences were observed (Thomas & Elias, 2010). A stronger spatial bias was found on the greyscales task, whereas a stronger object-based bias was found on the object luminosity task (Thomas & Elias, in press). When individual spatial conditions were examined, the image chosen most often was always located in the lower field. Stimulus type and spatial location interacted to determine which coordinate type contributes more strongly to leftward biases. We also found that the leftward bias on the greyscales task was stronger in the lower visual field during prolonged presentation and in the upper visual field during brief presentation. A global motion task was created to preferentially engage magnocellular projections to the dorsal stream. Isoluminant red/green and blue/yellow colour tasks, which preferentially engage parvocellular projections to the ventral stream, were also created. Leftward biases were seen on the greyscales and motion tasks. On an isoluminant colour task, biases were significantly weakened, suggesting leftward biases exhibited by neurologically normal people are mediated by magnocellular projections to the dorsal stream and this preferential processing leads to a lower visual field advantage on the greyscales task.

Over the last few decades, the Standard Model (SM) of particle physics has been used as a means of understanding the world around us. However, there is an increasing amount of data that suggests the SM of particle physics only describes nature up to energies of the electroweak scale. Extensions to the SM have been developed as a means of explaining experimental observation. If these extensions are indeed the correct mathematical descriptions of nature, the Large Hadron Collider (LHC), located at the European Center for Nuclear Research (CERN) near Geneva, Switzerland, is expected to produce new and exciting physics signatures that can shed light on the evolution of our universe since the early hypothesized Big Bang. Of particular interest are models that may lead to events with highly energetic tau lepton pairs. In this dissertation, focus is placed on a possible search for new heavy gauge bosons decaying to highly energetic tau pairs using a data sample corresponding to an integrated luminosity of 36 pb^-1 of proton-proton collisions at sqrt(s) = 7 TeV collected with the CMS detector at the CERN LHC. The number of observed events in the data is in good agreement with the predictions for SM background processes. In the context of the Sequential SM, a Z0 with mass less than 468 GeV/c^2 is excluded at 95 percent credibility level, exceeding the sensitivity by the Tevatron experiments at the Fermi National Accelerator Laboratory.

Deer-vehicle collisions (DVCs) along a 5.6-km segment of United States Highway 1 (US 1) on Big Pine Key (BPK), Florida responsible for approximately 26% of endangered Florida Key deer (Odocoileus virginianus clavium) annual mortalities. The Florida Department of Transportation (FDOT) constructed a 2.6-km long system of fencing, 2 underpasses, and 4 experimental deer guards to address DVCs along a portion of the US 1 roadway in 2001–2002. I evaluated the effectiveness of the project in reducing Key deer mortality by comparing (1) survival of radio-collared deer, (2) deer-vehicle collisions on US 1, and (3) determining the ability of deer to access the fenced segment. I found no significant difference in male or female survival. Key deer-vehicle collisions were reduced by 83–92% inside the fenced segment. However, overall US 1 Key deer-vehicle collisions did not change. Key deer entry into the fenced segment was minimized to 8 deer during the first-year resulting in 2 deer mortalities. I also assessed the potential impacts of the US 1 corridor project to Key deer movements by comparing (1) radio-collared Key deer annual ranges (2) radio-collared deer corridor movements, and (3) assessing Key deer underpass and corridor use. Female and male ranges and core areas did not change (P > 0.05). Deer movements within the US 1 corridor were comparable pre- (6 of 23 radio-collared deer crossed the corridor) and post-project (4 of 16). Infrared-triggered camera data indicate underpass movements increased over time. Collectively, post-project telemetry and camera data indicates US 1 highway improvements have not restricted Key deer movements. Hourly Key deer movement and US 1 traffic patterns were compared to annual US 1 DVCs. Hourly deer movements showed a positive correlation (P = 0.012, r = 0.505) to hourly DVCs for the full circadian period. Hourly US 1 traffic showed a significant positive relationship (P = 0.012, r = 0.787) with DVCs only during the night period. Evaluation of hourly deer movements and hourly traffic volume on US 1 found hourly DVCs to be the result of a combination between both variables.

Au travers de cette thèse, nous nous intéressons à la problématique de la détection des collisions au sein d'environnements virtuels, notamment dans le cadre de simulations interactives consistant en la manipulation de scènes complexes. Nos recherches se sont particulièrement orientées vers la mise en oeuvre de techniques d'optimisation dans ce contexte. Aussi, la principale contribution issue des travaux réalisés dans le cadre de cette thèse réside dans l'élaboration d'un algorithme fondé sur une approche évolutionniste. Baptisé ESPIONS, cet algorithme peut se voir utilisé de différentes manières. On peut cependant le définir comme un processus visant à identifier des champs de distances minimum locales entre des objets virtuels de natures diverses. Nous proposons également une étude expérimentale visant à caractériser l'influence des paramètres d'ESPIONS sur son comportement général, ceci dans le but d'identifier différents critères destinés à faciliter l'établissement de jeux de paramètres pertinents en fonction des problèmes considérés. Enfin, plusieurs implémentations de l'algorithme sont présentées en vu d'illustrer les différents modes opératoires introduits et d'évaluer les apports et limites de l'approche proposée.

Nous avons étudié la relaxation des polaritons dans une cavité contenant un gaz d'électrons de densité contrôlable. Dans un premier temps, la densité d'électrons a été mesurée. Elle peut être variée entre 0 et 10^11 cm-2. Nous avons ainsi pu étudier un nouveau mécanisme de relaxation : la relaxation par collisions polariton-électron, qui était encore mal connu auparavant. Ce mécanisme permet d'augmenter d'un ordre de grandeur les facteurs d'occupation dans les états de polariton proches de k//=0. La comparaison avec la relaxation par collisions polariton-polariton montre cependant que les deux mécanismes de collisions sont aussi efficaces l'un que l'autre, contrairement à ce qui avait été proposé théoriquement. La différence observée entre théorie et expérience est discutée dans le manuscrit. Enfin, nous avons étudié la photoluminescence résolue en temps des polaritons et montré que les modifications observées sont en grande partie dues aux mécanismes de formation des excitons.

The Department of Energy Oak Ridge Reservation (ORR) and the nearby adjoining City of Oak Ridge, Tennessee had experienced a rise in deer-vehicle collisions (DVCs) to the point where safety for employees and residents became a concern. I investigated the effect of hunting, land cover, road mileage, season, lunar phase, sex, and change in traffic patterns that coincide with work shifts on DVCs from 1975 - 2008. The study area was divided into grids of 1.5 km² each for administration and data recording by managing agencies. Statistical analyses were performed on the ORR (121 grids) and GIS analyses were performed on the entire study area that included ORR and the city of Oak Ridge (190 grids). The number of DVCs in 1975 was 16 and reached a high of 273 in 1985. Therefore, managers initiated a hunting program in 1985 and recorded deer harvest numbers by grid each year. Deer harvest has been occurring from 1985 until present, except when hunting was cancelled due to security concerns after the September 11 terrorist attacks in 2001. By 2008, the number of DVCs had decreased to 100 per year. When hunting first started in 1985, they harvested 926 deer. By 2008, that number was down to 481. I used GIS mapping to record DVCs, deer harvest per grid, landcover types, and mileage per grid to determine factors affecting DVCs on the smaller landscape. Following the initiation of annual hunts, both the annual deer harvest and the number of DVC’s have fallen, presumably because the overall deer population has declined from high pre-hunting levels. Deer harvest appears to be related to landcover characteristics, as a higher percentage of deer were harvested from forested areas than from other landcover types, as forested areas were most prominent. The months of October, November, and December had the highest DVC numbers. Increased traffic during starting and leaving shift times seem to increase the number of DVCs as well. Lunar phases only seem to significantly increase DVCs during the gestation and fawning seasons. Does are involved more frequently with DVCs than bucks during gestation, fawning and prerut, but not during the rutting season. I expect managers can use this data to guide intensive local management aimed at reducing DVCs by increasing the number of deer harvested and increased public education.