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In this work high-resolution numerical simulation (Large-Eddie Simulation, LES) has been used to study the characteristic factors causing and influencing the development of moist convective clouds. Through this work a 1D cloud-model was derived from first principles to represent the vertical profile of individual convective clouds. A microphysics framework was implemented to ensure identical behaviour in LES and cloud-model integration where the microphysical processes represented are numerically integrated using a novel adaptive step microphysics integration which uses the physical speed at which a process takes place to adjust the integration step size (in space and time). This work also introduces a simple representation of cloud-droplet formation which allows for super-saturation to exist in-cloud and through this provide more physical representation of the in-cloud state. Together with high-resolution simulation of isolated individual and interacting multiple clouds in environmental conditions leading to shallow convection, the 1D cloud-model was used to infer that the principal influence on moist convective clouds is the entrainment of air from a cloud’s immediate environment which is significantly different from the environmental mean state. This suggests that convection parameterisations must represent the influence of moist convective downdrafts to properly predict the vertical structure of convective clouds so as to correctly predict the cloud-top height and vertical transport. Finally it was found that cloud-base radius is not in itself adequate as a means of classification for defining cloud-types as clouds with the same cloud-base radius showed large variation (≈ 600m) in cloud-top height. Based on simulations of individual convective clouds it was found that 3D simulations are necessary to capture the full dynamic behaviour of convective clouds (2D axisymmetric simulations have too little entrainment) and that agreement with the 1D cloud-model could only be found when entrainment was diagnosed from simulation instead of being parameterised by the traditional Morton-Turner model and only for 2D axisymmetric simulations, suggesting that the 1D cloud-model will require further extension or the diagnosis of entrainment improved.

Extratropical cyclones are responsible for a substantial portion of midlatitude climate variability and contribute to widespread impacts. The characteristics of extratropical cyclones, such as their spatial distribution and intensity, are thought to be dependent on the large scale circulation. The relationship between cyclone characteristics and modes of large-scale climate variability has been investigated in previous studies, but interactions between modes of climate variability have largely been ignored. Since extratropical cyclone characteristics may be related to interactions between phases, quantifying these relationships is an important step in improving the climatology of extratropical cyclones. The goal of this study is to quantify relationships between modes of climate variability and characteristics of strong cyclones in the contiguous United States. Using historical sea-level pressure data, cyclone intensity, frequency, and spatial distribution are investigated using a cyclone definition that combines the requirement for low pressure (1000 hPa or lower) and positive (cyclonic) vorticity. The large scale modes of climate variability considered include El Niño Southern Oscillation (ENSO), the Pacific North American (PNA) mode, and the Arctic Oscillation (AO). The analysis is divided into three phases focusing on (1) establishing a background cyclone climatology within the study area, (2) quantifying differences in cyclone characteristics between the positive and negative phases of the individual modes of climate variability, and (3) examining the interactions between the modes of climate variability as they relate to extratropical cyclone characteristics. The results are expected to provide an improved baseline for evaluation of coupled climate models and also have the potential to improve seasonal climate predictability.

The modern era of particle physics is driven by experimental anomalies. Experimental efforts have become increasingly diverse and are producing enormous volumes of data. In such a highly data-driven scientific environment theoretical models are necessary to understand this data and to help inform the development of new experimental approaches. In this dissertation I present two significant contributions to this effort relevant to the energy, intensity, and cosmic frontiers of modern particle physics research. Part 1 of this dissertation discusses methods to understand modern dark matter direct detection results. In particular I present an analysis under the hypothesis of inelastic dark matter, which supposes that dark matter must scatter inelastically, i.e. that it must gain or loose mass during a collision with atomic nuclei. This hypothesis is attractive because it can alleviate otherwise contradictory results from a number of dark matter detection facilities. The main conclusion of this work is a presentation of the analytical tools, along with a mathematica package that can be used to run the analysis, and the discovery that there are regions of inelastic dark matter parameter space which are consistent with all current experimental results, and constraints. Part 2 of this dissertation discusses a phenomenon of modern interest called kinetic mixing which allows particles from the standard model to spontaneously transform into particles which experience a new, as of yet undiscovered, force. This phenomenon is relatively common and well motivated theoretically and has motivated significant experimental effort. In this work, I present an analysis of a general case of kinetic mixing, called nonabelian kinetic mixing. This work shows that, In general, kinetic mixing predicts the existence of a new particle and that, under certain conditions, this particle could be detected at modern particle colliders. Furthermore, the mass of this particle is related to the strength of kinetic mixing. This relationship suggests novel ways to constrain kinetic mixing parameter space, and if observed would provide a very striking indication that such a model is realized in nature.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Este estudo experimental verificou a eficÃcia do uso de um lacre plÃstico no fechamento do coto distal do cÃlon sigmÃide comparando com sutura manual em plano Ãnico, contÃnuo e extramucoso utilizando fio de polipropileno. Foram utilizados 30 animais (Canis familiaris) fÃmeas, pesando entre 8,0 e 18,0 kg, clinicamente sadios, oriundos do canil da Prefeitura Municipal de Teresina, PiauÃ. Foram distribuÃdos em dois grupos de 15 animais; submetidos a laparotomia com secÃÃo do cÃlon sigmÃide, com fechamento do coto distal com sutura cotÃnua e extramucosa com fio de polipropileno ( Grupo I â Controle) e fechamento do coto distal com lacre plÃstico ( Grupo II- Estudo ). Todos os animais de ambos os grupos foram submetidos à anastomose colo-retal, tÃrmino lateral e avaliados no trans e pÃs-operatÃrio imediato por mÃdico veterinÃrio, sendo a alimentaÃÃo à base de raÃÃo padrÃo e Ãgua, ad libitum, instituÃda quando se observou evacuaÃÃo. Todos os animais foram submetidos à eutanÃsia no 21 DPO apÃs anestesia venosa com Cloridrato de Cetamina e aplicaÃÃo de cloreto de potÃssio 20% via endovenosa ; realizou-se nova laparotomia e avaliaÃÃo da anastomose colo-retal, correspondendo o cÃto distal do sigmÃide ,este segmento foi submetido a teste de rompimento de sutura. Estatisticamente foi realizado teste estatÃstico de VariÃncia aplicando-se o Teste SNK e confirmado com teste Qui-quadrado. Durante realizaÃÃo do teste de tensÃo, ocorreu rompimento do fechamento do coto cÃlico distal em quatro animais de cada grupo, nÃo havendo diferenÃa significativa entre os grupos (p>0.05). O tempo operatÃrio mÃdio foi 27,7 min. E 24,7 min., nos Grupos I e II respectivamente, nÃo havendo diferenÃa estatisticamente significante entre os dois grupos (p=0,09). A pressÃo mÃdia de ruptura foi 145,0mmHg e 195,0mmHg nos Grupos I e II respectivamente, nÃo havendo diferenÃa estatisticamente significante entre eles (p=0,057). O fechamento do cÃlon distal com lacre apresentou a mesma seguranÃa e eficÃcia do fechamento com fio polipropileno 3-0. / The objective of this experimental study was to compare the efficacy of two techniques of distal sigmoid stump closure: plastic zip-tie versus manual, running extramucosal single-layer suture with polypropylene thread. The study included 30 clinically healthy female dogs (Canis familiaris) weighing 8−18 kg supplied by the local municipal dog pound (Teresina, PiauÃ). The animals were distributed in two groups of 15 animals each and submitted to laparotomy, colon resection and closure of the distal sigmoid stump with either running extramucosal suture using 3-0 propylene thread (Group I) or a plastic zip-tie (Group II). All animals were submitted to latero-terminal colorectal anastomosis and were evaluated transoperatively and immediately after surgery by a veterinarian. Standard chow and water was provided ad libitum once evacuation had been observed. On the 21st postoperative day the animals were anesthetized with Cloridrate Cetamina i.v. and euthanized with 20% potassium chloride i.v. A second laparotomy was performed to evaluate the colorectal anastomosis and submit the sigmoid stump to a wound disruption test. Findings were submitted to variance analysis, followed by the Student-Newman-Keuls test and the Chi-square test for confirmation. Wound disruption occurred in four animals from each group, with no statistically significant difference between the groups (p>0.05). The average time of surgery was 27.7 min (Group I) and 24.7 min (Group II), with no statistically significant difference between the groups (p=0.09). The average disruption pressure was 145.0 mmHg (Group I) and 195.0 mmHg (Group II), with no statistically significant difference between the groups (p=0.057). Closure of the sigmoid stump may be as safely performed with plastic zip-tie as with conventional continuous suture using 3-0 polypropylene thread.

Un cross-over entre la matière nucléaire ordinaire et le plasma de quarks et gluons (PQG) est prédit par la QCD sur réseau à bas PB et haute température. Expérimentalement les collisions d'ions lourds ultrarelativistes sont utilisées pour étudier cet état dense et chaud. Produits lors d'un processus dur en début de collision, un parton de grande énergie en perd dans le milieu avant de fragmenter en une gerbe de hadrons appelée jet. Une étude de la modification de la structure et de la fragmentation du jet dans le milieu par rapport au vide permet d'améliorer notre connaissance du PQG. Les fonctions de fragmentation (FF) d'un jet décrivent les distributions en impulsion des hadrons dans ce dernier. Dans les collisions proton-proton (pp), leur mesure est importante pour comprendre les mécanismes de fragmentation de partons. Dans les collisions noyau-noyau, elle permet d'étudier les mécanismes de perte d'énergie. Cependant, la présence d'un important bruit de fond qui fluctue rend la mesure complexe. Il a alors été suggéré de mesurer les moments des FF qui y seraient moins sensibles. Le détecteur ALICE au LHC a des capacités de trajectométrie uniques permettant la mesure des particules chargées jusqu'à des impulsions de 150 MeV/c rendant possible une étude fine de la structure du jet et de ses FF. Les calorimètres électromagnétiques (EMCal et DCal) peuvent aussi être utilisés pour améliorer la mesure de l'énergie du jet. Nous présentons les mesures des FF des jets chargés et les premières études des moments des FF dans les collisions pp à .s=2.76 TeV dans ALICE. Une partie du travail est aussi dédiée à l'implémentation de la géométrie de DCal dans le logiciel d'analyse. / A cross-over between ordinary nuclear matter and a state of deconfined quarks and gluons, the Quark Gluon Plasma (QGP), is predicted by lattice QCD at low PB and high temperature. Experimentally, ultra-relativistic heavy ion collisions are used to produce and to study the hot and dense QGP medium. Produced in a hard scattering at the early stage of the collision a highly energetic parton is expected to lose energy in the medium before fragmenting into a spray of hadrons called jet. A study of the modification of the jet structure and of its fragmentation pattern in medium compared to the vacuum case should provide insights into the QGP properties. The jet fragmentation functions (FF) describe the momentum distribution of hadrons inside a jet. In proton-proton (pp) collisions their measurement is important for understanding the mechanisms of parton fragmentation while it can shed light on the energy loss mechanisms in nucleus-nucleus (AA) collisions. However, the presence of a large fluctuating background in AA makes the measurement a challenging task. The use of FF moments has been proposed to overcome this difficulty. The ALICE detector at the LHC has unique tracking capabilities enabling to measure charged particles down to transverse momenta of 150 MeV/c. This allows assessing possible modifications of the jet structure and FF. The electromagnetic calorimeters (EMCal and DCal) can also be used to improve the measurement of the jet energy. We present the measurements of charged-jet FF and the first studies of FF moments in pp collisions at .s=2.76 TeV in ALICE. Part of the work is also dedicated to the implementation of the DCal geometry in the ALICE offline software.