Concurrence of adenocarcinoma and large-cell neuroendocrine carcinoma of the stomach is a rare condition. Here, we report a case of gastric collision tumour with large-cell neuroendocrine carcinoma and adenocarcinoma. A 71-year-old Peruvian man presented with nausea, epigastric pain, and weight loss for seven months. An Endoscopic evaluation revealed a huge ulcerative and infiltrative mass in the upper and middle third of the stomach. The patient underwent a D2 total gastrectomy. Microscopically, two separated and attached ulcerative lesions were recognised. The proximal to the cardial lesion showed neuroendocrine morphology and immunoreactivity for synaptophysin, and the other a moderated tubular adenocarcinoma Borrmann type III. Both lesions invaded serosa and lymph nodes metastases were found in 17 of 41 lymph nodes retrieved (one lymph node with neuroendocrine metastatic deposits).

De façon générale, la physique des collisions concerne l'étude des phénomènes induits par l'interaction de particules en mouvement. En physicochimie moléculaire et en physique atomique, cadres dans lesquels s'inscrit cette thèse, les interactions mises en jeu sont coulombiennes et les partenaires de la collision sont des espèces atomiques ou moléculaires, neutres ou chargées. Celles-ci sont susceptibles de subir au cours de la collision des modifications importantes de leur cortège électronique, à la source même de processus secondaires variés présentant un grand intérêt, par exemple, dans la modélisation de systèmes complexes tels que les plasmas, les milieux astrophysiques ou biologiques. Notre étude s'appuie sur une description théorique semi-classique non-perturbative des processus multi-électroniques au cours de collisions atomiques et moléculaires, à des énergies telles que la vitesse relative des partenaires est comparable à celle de leur électrons de valence. Dans deux systèmes " benchmark " (H+ - Li , He - H2+), nous avons mis en évidence respectivement l'existence de couplages complexes entre voies de réaction impliquant les électrons internes et de valence du lithium et des phénomènes d'interférences et de diffraction d'ondes de matière. Nous avons également étudié des systèmes de collision plus complexes impliquant le carbone, en analysant tout particulièrement des phénomènes multi-électroniques (collisions C(+) - He) - hors approximation des électrons indépendants - et multi-centriques (collisions proton-graphène). Pour ce dernier système, les résultats obtenus ont permis de mettre en évidence les principes d'une nouvelle technique d'imagerie de matériaux 2D. / In general, the Physics of collisions concerns the study of phenomena induced by the relative motion of interacting particles. In chemical physics and atomic physics, which are the area covered by this PhD, the interactions are Coulombic and the colliding partners are atoms or molecules which can be neutral or charged. During the collision, they are likely to undergo important modifications of their electronic environment, which can be the source of various secondary processes that are of great interest, for example, in the modelling of complex systems such as plasmas or astrophysical and biological media. Our study is based on a close-coupling semi-classical description of the multielectronic processes occurring in the course of atomic and molecular collision at impact energy such as the relative velocity of the partners are of the same order of magnitude than the classical velocity of their valence electrons. We have studied two ?benchmark? systems (H+ - Li , He ? H2+), for which we have respectively highlighted the existence of couplings between channels involving inner and outer-shell electrons of lithium, and, wave matter interferences and diffraction phenomena. We have also studied more complex colliding systems involving the carbon nucleus in analyzing multielectronic (C(+) ? He collisions) and multicentric (proton-graphene collisions) phenomena. For the latter system, the results obtained have allowed us to bring out the principles of a new two-dimensional material imaging technique.

A substantial number of whiplash injuries are reported for motor vehicle accidents which produce little or no structural damage to the automobile. These injuries are predominantly associated with rear-end type accidents affecting passengers of the struck vehicle. Since passengers of the striking vehicles are not reporting as many injuries for the same accidents, occupant and vehicle dynamics experienced during low speed-rear impacts were proposed to be a major source of the whiplash claims. A review of previous research revealed that little information exists for this type of accident. In general, vehicle safety research and government regulations have been directed towards occupant mortality - not injury - in frontal collisions. Occupant dynamics research has been limited to sled testing, using modified seat structures, or out-of-date vehicle models. Full scale, rear impact, crash testing has concentrated on high impact speeds (above 30 km/h) where significant structural deformation occurs. A research program was designed to investigate the occupant and vehicle dynamics during low speed - rear impacts. Experimental research was undertaken to document the structural performance of vehicles, noting the impact speeds necessary to initiate the crush mechanisms in the rear portion of the vehicle. To facilitate this testing, a pendulum impactor, based on the government test procedures, was designed and built to consistently reproduce impact speeds below 20 km/h. A total of 56 rear impact tests were conducted with 1977-1982 Volkswagen Rabbits. The vehicle wheels were locked to represent a vehicle stopped in traffic - the most commonly reported whiplash producing accident. An anthropometric test dummy was used to represent a front seat passenger during the tests. High speed video recordings of the tests were digitized to provide kinematic information on the occupant and vehicle response. Accelerometers were incorporated into the last 24 tests to monitor the acceleration levels at the bumper mount, seat mount and within the dummy. Information obtained from this testing suggested that permanent structural damage was only visible when an impact speed between 14 and 15 km/h was experienced by the vehicle. Very little frame deformation occurs for impact speeds below this value. Below this threshold, the vehicle frame can be considered rigid; vehicle response being dominated by the compliance of the bumper and suspension systems as well as sliding of the locked wheels. The accompanying occupant response was a differential rebound of the head and shoulders off the seatback and head restraint. This relative motion between the head and torso was evident in each test and increases the potential for injury. Typical occupant response observed consisted of an initial loading and deflection of the seatback due to the occupant's inertia followed by the release of this stored spring energy as the occupant was catapulted forward. It is this elastic behaviour of the seatback which is the likely cause of whiplash injury. Resulting head velocities were found to be in the order of 1.5 - 2 times the resulting vehicle speed. Initial occupant postures which increased the distance between the torso and seatback tended to increase the dynamic loading experienced by the passenger. Analytical modelling of the vehicle was initiated as the groundwork for full occupant-vehicle simulation. A finite element model of the vehicle frame, bumper, and suspension was created. Previously obtained empirical information suggested that a non-linear bumper and suspension system connected to a rigid frame would be an acceptable approximation. A parametric analysis of bumper stiffness and braking conditions was conducted in a 30 simulation matrix. General kinematic trends of the tests were observed in the simulations, however, limitations in the material properties introduced a much stiffer response than that experimentally observed. Results from this study show that little protection is offered to an occupant during a rear end collision. Impact energy management within the vehicle may not be adequate to prevent injury. Improved occupant protection requires the highly elastic behaviour of the vehicle frame and seatback to be attenuated. This will eliminate the amplification of vehicle motion through the seatback to the occupant. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

The particle-bubble interaction is found in industrial applications with the purpose of selective separation of materials especially in the mining industry. The separation is achieved with the use of bubbles that collect particles depending on their hydrophobicity. There are few experimental studies involving a single interaction between a bubble and a particle. The purpose of this work is to understand this interaction by the study of a single bubble interacting with a single particle. Experiments were conducted using ultra-pure water, glass particles and air bubbles. Single interactions of particles with bubbles were observed using two high speed cameras. The cameras were placed perpendicular to each other allowing to reconstruct the three-dimensional position of the particle, the bubble and the particle-bubble aggregate. A single size of particle was used varying the size for the bubbles. It was found that the attachment of a particle to a bubble depends on its degree of hydrophobicity and on the relative position of the particle and the bubble before they encounter.

In recent years, State Road Route 114 which is located in Montgomery County, Virginia, has gained a bad reputation because of numerous traffic accidents. Most of these accidents resulted in loss of lives and property. Although there are many suggestions and proposals designed to prevent these acidents, to date no actions is taken yet. The focus of this research is to explore a technology-based, low cost solution that will lower or eliminate the risk of accidents on this two-lane rural highway. / Master of Science

Keeping a safe distance from the forward-leading vehicle is an essential feature of modern Advanced Driver Assistant Systems (ADAS), especially for transportation companies with a fleet of trucks. We propose in this thesis a Forward Collision Warning (FCW) system, which collects visual information using smartphones attached for instance to the windshield of a vehicle. The basic idea is to detect the forward-leading vehicle and estimate its distance from the vehicle. Given the limited resources of computation and memory of mobile devices, the main challenge of this work is running CNN-based object detectors at real-time without hurting the performance. In this thesis, we analyze the bounding boxes distribution of the vehicles, then propose an efficient and customized deep neural network for forward-leading vehicle detection. We apply a detection-tracking scheme to increase the frame rate of vehicle detection and maintain good performance. Then we propose a simple leading vehicle distance estimation approach for monocular cameras. With the techniques above, we build an FCW system that has low computation and memory requirements that are suitable for mobile devices. Our FCW system has 49% less allocated memory, 7.5% higher frame rate, and 21% less battery consumption speed than popular deep object detectors. A sample video is available at https://youtu.be/-ptvfabBZWA.

Maternal trauma is the leading non-obstetric cause of maternal and fetal death. Because the anatomy of a pregnancy is distinct, and highly transient, the pregnant woman and her fetus are both susceptible to injuries which are not seen in the typical trauma patient. The pregnant uterus, the placenta, and the fetus are all relatively poorly supported, as compared with non-transient abdominal or thoracic organs, which can lead to injuries such as uterine rupture, placental abruption, and fetal trauma or death. The leading cause of maternal trauma is automotive collision, and other common causes include violence, falls, and other accidents. Automotive collision is often researched with more traditional physical experiments such as post-mortem crash testing, but this form of study is exceedingly difficult with the pregnant subject due to ethical and logistical issues. Computational simulations of automotive collisions have received much attention as a method of performing experiments without the use of physical specimens, and have been successful in modeling trauma. These simulations benefit from constitutive relationships which effectively describe the biomechanical and structural behaviors of biological tissues. Internal state variable models driven by microstructural data offer the potential for capturing a myriad of material behaviors intrinsic to many biological tissues. The studies presented include many advances in the existing research of maternal trauma. These studies include advanced biomechanical and microstructural characterization of the placenta, the organ commonly injured in maternal trauma, to capture stress state and strain rate dependencies, as well as microstructural evolution across stress states. The studies also describe the construction of a finite element mesh of a near-term pregnant woman and fetus from medical images. This finite element mesh was implemented in a simulation of maternal trauma based on one of the only post mortem studies of pregnant cadavers ever reported in the literature. The results are a significant advancement for trauma simulation research.

As UASs (Uncrewed Aerial System) are further integrated into operations, the need for on-board environmental perception and sensing is necessitated. An accurate and reliable creation of a 3D map resembling an aircraft's surrounding is crucial for accurate collision avoidance and path planning. Consumer UASs are now being equipped with sensors to fulfill such a requirement – but no system has been proven as capable of being fully relied upon. With many sensing options available, there are several constraints regarding size, weight, and cost that must be considered when developing a sensing solution. Additionally, the robustness of the system must not be diminished when moving to a system that minimizes size, weight, or cost. An analysis of different sensing technologies that small rotary-wing aircraft (below 25kg) can be outfitted with for collision avoidance is performed. Several sensing technologies are initially compared through technology analyses and controlled experiments. The topmost systems were then further integrated onto a small low-cost quadcopter for flight testing and data acquisition. Ultimately, a fusion between stereo vision imagery and radar was deemed the most reliable method for providing environmental data needed for collision avoidance. / Master of Science / As drones become further integrated in several industries, it is important that their operations are conducted in a safe manner. Most drones today have a limited ability to sense and react to the environment around them. This results in the risk of the drone colliding with people or obstacles such as buildings, trees, light poles, etc. Thus, an accurate and reliable creation of a 3D map resembling a drone's surrounding is crucial for collision avoidance. This would allow for the avoidance of people and obstacles during automated flights where the drone may encounter obstacles during flight. With many sensing options available, there are several constraints regarding size, weight, and cost that must be considered when developing a sensing solution. Additionally, the reliability of the system must be of the topmost priority to ensure safe operations. An analysis of different sensing technologies that small rotary-wing aircraft (below 25kg) can be outfitted with for collision avoidance is performed. Rotary-wing aircraft are a specific subset of drones that are capable of vertical takeoff, landing, and hover (i.e not planes). An analysis regarding the several sensing technologies was first conducted to select the three topmost solutions. These solutions were then integrated onto a small low-cost quadcopter for data collection and flight testing. Ultimately, a combination of stereo vision imagery and radar was deemed the most reliable method for collecting collision avoidance data.

No description available.

This dissertation consists of three manuscripts that will be submitted for publication. All three of these examine various aspects of the evolution of the India-Asia suture zone in southern Tibet after the India-Asia collision. Continent-continent collision is one of the basic tectonic plate boundary types, has occurred repeatedly throughout geologic history, and represents one of the principle mechanisms responsible for the formation of high elevation plateaus and orogens. Uplift within these zones has also drastically changed the earth's climate and atmospheric circulation, and erosion from continental collision has resulted in some of the thickest accumulations of sediment in the world (Curray, 1991; Einsele et al., 1996). However, despite the global significance of continental collision, much of the fundamental geodynamic and geologic processes governing these events remain enigmatic. This is the result of several factors. First and foremost, intense deformation and uplift of rocks, often from mid crustal levels, over very short periods of time (Hodges and Silverberg, 1988; Seward and Burg, 2008; Zeitler et al., 2014) results in the erosive removal of much of the geologic record of a collision zone. Second, because the best modern example of continental collision is the Tibet-Himalayan system, the study of continental collision in general has been hampered by high elevations, remoteness, difficult working conditions, and political unrest. The work presented here represents a step toward better understanding the geology, geologic history, and geodynamic evolution of the Tibetan Plateau, the Himalaya, and the India-Asia collision. This has been accomplished through study of two of the post-collisional sedimentary basins which formed near or within the India-Asia suture zone. Appendix A addresses the structure, sedimentology, age, and provenance of the Liuqu Conglomerate. The key conclusions of this section are: 1) The Liuqu Conglomerate was deposited in north flowing, stream dominated alluvial fans. These were located situated in a wedge-top position within a system of north verging thrust faults likely associated with the Great Counter Thrust, and sediment was accommodated via burial beneath thrust structures. 2) The age of the Liuqu Conglomerate has been refined to ~20 Ma based on detrital zircon U-Pb and fission track dating, ⁴⁰Ar/³⁹Ar dating of biotite from a cross-cutting dike, re-analysis of previously published pollen data, regional structural considerations, and oxygen isotope composition of paleosol carbonates. 3) Sand-sized and finer-grained sediment eroded from the southern margin of Asia prior to collision was transported southwards across the Xigaze forearc basin, deposited within the subduction trench, and then accreted within the subduction complex mélange. After collision, this sediment was eroded from the mélange and shed northward into the India-Asia suture zone. Appendix B focuses on the abundant paleosols preserved within the Liuqu Conglomerate. This study uses major element geochemistry of these paleosols and stable isotope analyses of paleosol carbonates to constrain the degree and type of chemical weathering, and thus the paleoclimate and paleoelevation, of the Liuqu Conglomerate. The key conclusions of this paper are: 1) at ~20 Ma, the India-Asia suture zone experienced warm and wet conditions that promoted intense chemical weathering of soils exposed in the inactive portions of alluvial fans. Paleorainfall is estimated at ~1500 mm/yr, and weathering intensity was similar to soils formed in the Neogene Siwalik Group of India, Nepal, and Pakistan, which formed under wet, semitropical, and low elevation conditions. 2) The India-Asia suture zone experienced these conditions at ~20 Ma despite extensive deformation and crustal thickening which has been documented within the Tethyan Himalayan and Himalayan thrust belts. This crustal thickening should have resulted in the (surface) uplift of the entire India-Asia collision zone, and there is evidence that at least some portion of the Himalayan crest was at or near modern elevations by ~17 Ma. Our results require either that the Tethyan Himalaya and India-Asia suture zone were not uplifted despite as much as 40 million years of intense crustal shortening or that these regions attained high elevation prior to ~20 Ma, and then lost elevation around this time before being immediately re-uplifted. The viability of these two scenarios cannot be explicitly tested with the data presented in this chapter; however, based on the data presented in Appendix C, I strongly favor the second scenario. Appendix C focuses on the Kailas Formation, exposed ~20 km north of the Liuqu Conglomerate within the India-Asia suture zone. The Kailas Formation is exposed along ~1300 km of the India-Asia suture zone. For this study, I present new sedimentologic, provenance, and geochronologic data for the Kailas Formation. Key findings of this study are that 1) the Kailas Formation is younger in the center of the suture zone, near 90°E, and becomes progressively older to the west; preliminary data suggest that these rocks are older to the east as well, but additional age constraints are required. 2) The pattern of sedimentation documented for the Kailas Formation is nearly identical to the spatio-temporal pattern of adakitic and ultrapotassic rocks in southern Tibet. These rocks have been attributed to rollback and breakoff of the Indian continental slab. Sedimentation within the Kailas basin has also been attributed to rollback of the Indian slab (DeCelles et al. 2011), and this idea is corroborated by the agreement of the sedimentary and magmatic records. 3) This presents an interesting possibility for explaining the existence of low elevations within the India-Asia suture zone at ~20 Ma, as documented in Appendix B. High elevation topography produced by crustal shortening and thickening likely remained intact until slab rollback and breakoff started around 30 Ma and caused the India-Asia suture zone to experience large scale extension and subsidence. The Kailas Formation was deposited in the resulting basin, which opened first in the west, and propagated eastward. After slab breakoff occurred, contractional deformation would have resumed, and the area would have been quickly uplifted to its modern elevations.