Common mullein (Verbascum thapsus) is a non-native plant threatening the integrity of natural ecosystems throughout California. Mechanical, chemical, and biological methods have been utilized for control of common mullein. The objective of this study was to determine which of the following treatment cycles is most effective to reduce populations of common mullein at Lava Beds National Monument: annual (once per year), biennial (once every two years), or no treatment. Vegetation type, natural features, site characteristics, and human disturbance were factors considered when analyzing common mullein distribution and abundance. Forty-five pre-existing plots with populations of common mullein were visited during summer 2005. The interrelationship of common mullein with the surrounding high-desert plant communities was assessed by three vegetation sampling methods. Density, cover, and common mullein stages were measured by point-intercept transects, belt transects, and circular macroplots. Simple linear regressions were performed using common mullein density as the dependent variable with multiple independent variables such as shrub, rock, soil, and grass cover. Analysis of variance test showed no significant relationship between density of common mullein and the three treatment cycles (p > 0.05). However, trends observed imply that annual treatment reduces the population of large rosettes and reproductive stalks over no-treatment and biennial treatment. A bivariate correlation test found the circular macroplot to be similar to belt transects for measuring common mullein density (r = 0.84). / Department of Natural Resources and Environmental Management

A erupção histórica de 1580 A.D. ocorreu ao sudoeste da Ilha de São Jorge, Açores recobrindo uma área total de 4 km². Este trabalho teve como objetivo caracterizar as diferentes morfologias de lava de 1580 A.D, juntamente com a definição de padrões petrográficos e geoquímicos. A erupção gerou quatro flow fields: Ribeira do Almeida, Queimada, Ribeira do Nabo I e Ribeira do Nabo II. A descrição detalhada das lavas permitiu identificar spiny, sheet, e slabby pahoehoe e derrames do tipo ‘a´ā. Próximo aos cones, derrames do tipo ‘a´ā são descritos. Com a constante erupção, estas lavas fluem em direção a costa formando deltas de lava ao entrar em contato com a água. Estes deltas geram um relevo sub-horizontal favorecendo a colocação de derrames do tipo sheet pahoehoe. A contínua alimentação interna favorece o espessamento dos derrames, podendo gerar o rompimento da superfície formando derrames slabby pahoehoe. Os estágios finais da erupção são marcados por derrames do tipo ‘a´ā canalizados lateralmente e sobre os derrames do tipo sheet pahoehoe. A variação na superfície dos derrames é controlada pelas taxas de efusão e pela topografia. Petrograficamente, todas as lavas da erupção de 1580 A.D. são olivina basaltos. Os dados geoquímicos indicam uma afinidade magmática alcalina com os termos menos diferenciados localizados na região de Ponta Queimada. Isto pode ser explicado por uma constante recarga de magma mais primitivo na câmara magmática. Os padrões de ETR normalizados sugerem que os basaltos estudados foram gerados a partir de um baixo grau de fusão de uma fonte profunda e enriquecida do tipo OIB. O estudo dos aspectos físicos dos derrames de 1580 juntamente com a petrografia e geoquímica permitiram compreender a história geológica deste evento. / The historic eruption of 1580 A.D. occurred in the southwestern of São Jorge Island, in the central Azores covering a total area of 4 km². This work provides a characterization of the distribution and morphology of the 1580 A.D. lava flows, integrated to petrography and geochemistry. The eruption formed four distinct flows fields: Ribeira do Almeida, Queimada, Ribeira do Nabo I and Ribeira do Nabo II. Detailed geological analysis allowed the identification of spiny, sheet and sllaby pahoehoe and ‘a´ā lava morphotypes. Near the vent, the flow fields are characterized by channelized ‘a´ā flows. With continuous eruption, these lavas flowed downwards forming fan-shaped lava deltas when entering the sea. Sheet pahoehoe flows overlay the ‘a´ā lavas and with continuous inflation the surface of the flows breaks generating slabby pahoehoe surface. The gradual increase in surface fragmentation form rubbly surfaces. In the late stages of the eruption channelized ‘a´ā flows were emplaced, depositing laterally and over the sheet pahoehoe flows. The variations in the lava surface are controlled by the effusion rates and the topography. Petrographically, all lava flows are olivine basalts. The chemistry of the basalts indicate an alkaline nature for the 1580 volcanism. The less-evolved compositions are found in Ribeira do Almeida and this fact can be related to continuous recharge of the magma chamber with more primitive melts. Normalized REE profiles show that the basalts were generated by low volumes of melt of an enriched OIB source. The study of the physical aspects of 1580 lava flows with petrography and geochemistry allowed understand the geologic history of this event.

A erupção histórica de 1580 A.D. ocorreu ao sudoeste da Ilha de São Jorge, Açores recobrindo uma área total de 4 km². Este trabalho teve como objetivo caracterizar as diferentes morfologias de lava de 1580 A.D, juntamente com a definição de padrões petrográficos e geoquímicos. A erupção gerou quatro flow fields: Ribeira do Almeida, Queimada, Ribeira do Nabo I e Ribeira do Nabo II. A descrição detalhada das lavas permitiu identificar spiny, sheet, e slabby pahoehoe e derrames do tipo ‘a´ā. Próximo aos cones, derrames do tipo ‘a´ā são descritos. Com a constante erupção, estas lavas fluem em direção a costa formando deltas de lava ao entrar em contato com a água. Estes deltas geram um relevo sub-horizontal favorecendo a colocação de derrames do tipo sheet pahoehoe. A contínua alimentação interna favorece o espessamento dos derrames, podendo gerar o rompimento da superfície formando derrames slabby pahoehoe. Os estágios finais da erupção são marcados por derrames do tipo ‘a´ā canalizados lateralmente e sobre os derrames do tipo sheet pahoehoe. A variação na superfície dos derrames é controlada pelas taxas de efusão e pela topografia. Petrograficamente, todas as lavas da erupção de 1580 A.D. são olivina basaltos. Os dados geoquímicos indicam uma afinidade magmática alcalina com os termos menos diferenciados localizados na região de Ponta Queimada. Isto pode ser explicado por uma constante recarga de magma mais primitivo na câmara magmática. Os padrões de ETR normalizados sugerem que os basaltos estudados foram gerados a partir de um baixo grau de fusão de uma fonte profunda e enriquecida do tipo OIB. O estudo dos aspectos físicos dos derrames de 1580 juntamente com a petrografia e geoquímica permitiram compreender a história geológica deste evento. / The historic eruption of 1580 A.D. occurred in the southwestern of São Jorge Island, in the central Azores covering a total area of 4 km². This work provides a characterization of the distribution and morphology of the 1580 A.D. lava flows, integrated to petrography and geochemistry. The eruption formed four distinct flows fields: Ribeira do Almeida, Queimada, Ribeira do Nabo I and Ribeira do Nabo II. Detailed geological analysis allowed the identification of spiny, sheet and sllaby pahoehoe and ‘a´ā lava morphotypes. Near the vent, the flow fields are characterized by channelized ‘a´ā flows. With continuous eruption, these lavas flowed downwards forming fan-shaped lava deltas when entering the sea. Sheet pahoehoe flows overlay the ‘a´ā lavas and with continuous inflation the surface of the flows breaks generating slabby pahoehoe surface. The gradual increase in surface fragmentation form rubbly surfaces. In the late stages of the eruption channelized ‘a´ā flows were emplaced, depositing laterally and over the sheet pahoehoe flows. The variations in the lava surface are controlled by the effusion rates and the topography. Petrographically, all lava flows are olivine basalts. The chemistry of the basalts indicate an alkaline nature for the 1580 volcanism. The less-evolved compositions are found in Ribeira do Almeida and this fact can be related to continuous recharge of the magma chamber with more primitive melts. Normalized REE profiles show that the basalts were generated by low volumes of melt of an enriched OIB source. The study of the physical aspects of 1580 lava flows with petrography and geochemistry allowed understand the geologic history of this event.

L'ablation par radiofréquence constitue un des traitements des tachycardies ventriculaires, en association avec les drogues anti-arythmiques et l’implantation d'un défibrillateur. L’objectif principal de cette thèse est de mieux comprendre le substrat arythmogène non seulement à l’aide d'imagerie cardiaque (IRM et scanner) de haute résolution et de cartographie de haute densité, en utilisant des cathéters multipolaires. Cela nous permettra d'analyser la relation structure-fonction. Nous avons étudié cette relation sur différents types de substrats (ICM, NICM, DAVD, et myocardites). Nous avons ainsi prouvé la supériorité de la cartographie de haute densité obtenue à partir de cathéters multipolaires, comparativement aux données recueillies par l’imagerie, dans l’identification de la cicatrice arythmogène et la détection des LAVA. La deuxième partie de cette thèse concerne l’étude du substrat arythmogène épicardique. Nous avons ainsi décrit la technique de cartographie par voie percutanée antérieure, puis démontré l'efficacité des procédures uniquement avec abord épicardique. La segmentation du nerf phrénique et des artères coronaires ont permis de diminuer le taux de complications théoriquement liés à cet abord. Nous avons poursuivi ce travail avec l’analyse des sites d'intérêt de l'ablation des TV: les LAVA. Après une description de la stratégie d’élimination des LAVA, nous avons tenté de trouver des prédicteurs permettant de localiser les sites de LAVA, à partir des données d'imagerie. Quand l'imagerie montre une cicatrice intraseptale ou intramurale, les LAVA ne peuvent pas être enregistrés avec la cartographie et des alternative techniques d'ablation sont nécessaires comme une ablation bipolaire, l'alcoolisation intra coronaire et l'ablation avec l'aiguille irriguée. Le dernier chapitre est une revue sur le futur de l'imagerie, de la cartographie et de l’ablation des tachycardies ventriculaires. Une meilleure compréhension du substrat arythmogène pourrait améliorer l'efficacité et la sécurité des ablations de tachycardie ventriculaire. / Radiofrequency (RF) catheter ablation is an effective treatment strategy for scar-related ventricular tachycardia (VT), resistant to anti-arrhythmic drugs and intracardiac defibrillator (ICD) placement. The goal of this thesis was to better understand and characterize the arrhythmogenic VT substrate in different cardiomyopathic processes: ischaemic cardiomyopathy (ICM), non-ischaemic cardiomyopathy (NICM), arrhythmogenic right ventricular cardiomyopathy (ARVC) and myocarditis. For this purpose, we combined high resolution imaging including different modalities and high resolution electrical mapping to better understand the structure-function relationship. We focused on multiple different aspects of VT ablation as outlined below. The first part of this thesis focuses on the role of multipolar mapping catheters and imaging to analyze their structural and functional relationship. We demonstrated superiority of high density mapping with multipolar mapping on conventional mapping in detection of scar, channels, local abnormal ventricular activity (LAVA) and sensitivity for near field signals. The second part of this thesis focuses on ablation of epicardial VT substrate. We demonstrated the efficacy and safety of epicardial only procedures in a highly selected population. We used imaging to have access to the exact anatomy of the heart, to image the substrate but also to increase the safety of ablation procedures by imaging the phrenic nerve and the coronary artery system. The third part of this thesis focuses on analysis of the mapping and ablation of potential targets for scar-related VT ablation. Within this context, we identified predictors of interesting ablation (LAVA) sites based on preprocedural imaging. We also analyzed the role of alternative strategies such as bipolar ablation, ethanol ablation and irrigated needle ablation to ablate intramural and intraseptal substrate, 18 often resistant ablation targets. Overall, we demonstrate that novel imaging, mapping and ablation techniques potentially improve the outcome of VT ablation.

[pt] Esta pesquisa analisou os possíveis impactos na rentabilidade de empresas que tiveram seus principais executivos presos após o início da operação Lava- Jato. A operação Lava-Jato foi deflagrada pela Polícia Federal, buscou e busca investigar contratos nos quais empreiteiras corrompiam os dirigentes por trocas de contratos com as empresas apontadas nesse estudo, e repassavam propinas aos partidos políticos. Os atos investigados na operação enquadram-se na categoria de crimes corporativos. Para esta análise utilizou-se um estudo de evento a fim de identificar retornos anormais nos preços das ações das empresas em questão. A amostra analisada compreendeu as três empresas de capital aberto e os preços diários de suas ações em um intervalo de dez dias antes e dez dias depois das datas das respectivas prisões. A partir desta análise foi possível chegar a uma conclusão sobre como as prisões dos executivos impactaram a rentabilidade das empresas. / [en] This research examined the possible impact on the profitability of companies who had their main executives arrested after the beginning of operação Lava-Jato. The operação Lava-Jato was triggered by Polícia Federal and deems to investigate the contracts on which the contractors bribed the directors in exchange of contracts with the companies mentioned in this study and repaid it to political parties. The acts mentioned under the scope of operação Lava-Jato are classified as corporate crimes. To accomplish this, there was an event study to identify the existence of abnormal returns in the stock prices of the mentioned companies. The sample comprised the three companies and their respective daily stock prices on an interval of ten days before and ten days after the arrest dates. From this analysis it was possible to conclude in relation to how the arrest of main executives impacted the companies profitability.

Subduction zone volcanoes are a major natural hazard, frequently endangering lives and livelihoods. The eruptive history of many subduction zone volcanoes includes the extrusion of blocky, silicic lava that forms domes or flows, but we do not yet understand what determines the duration of dome-forming behaviour, what path magma may take to the surface, or how these systems may change over time. This thesis presents an investigation of the Santiaguito complex of lava domes and flows in Guatemala, which has been erupting continuously since its inception in 1922. The Santiaguito lavas are predominantly dacitic to andesitic, with a gradual reduction in SiO2 content from ~66 wt% in the 1920s, to ~62 wt% in 2002. This is consistent with a ~15% decrease in the extent of fractional crystallization over that time. The compositions of plagioclase phenocryst cores indicate a diminished role for magma mixing after the 1940s. I model the Santiaguito system as progressively extracting magma from an extensive, chemically-stratified storage zone. Petrological data are consistent with a storage zone extending from ~25 to ~12 km depth, and magma storage temperatures of ~940 to ~980°C. Phenocryst-hosted apatites suggest melt in this storage zone contained 401 to 1199 ppm S, 600 to 1300 ppm F, and 4100 to 6200 ppm Cl. Ascending magma may pass slowly through a conduit bottleneck, or plug, at shallow depths; groundmass texture suggests that melt rigidifies at or near the base this plug. Pre-eruptive melt volatile concentrations suggest time-averaged fluxes of 40 to 263 Mg d-1 SO2, 32 to 145 Mg d-1 HF, and 247 to 708 Mg d-1 HCl, giving ratios of 0.6 to 0.8 HF/SO2, and 2.7 to 6.2 HCl/SO2. These results are consistent with the few direct measurements of SO2 at Santiaguito, and with measured halogen emissions from other silicic dome-forming systems.

Geóloga / El Complejo Volcánico Lonquimay (CVL) se encuentra en la Zona Volcánica Sur (38°). Ha estado activo principalmente durante el Holoceno, y ha generado productos esencialmente andesíticos. El CVL está compuesto por un estratovolcán principal, de un volumen cercano a los 20 km3, que se encuentra dividido en cinco unidades, donde las lavas más antiguas presentan longitudes de hasta 15 km, con morfologías de tipo aa, mientras que las coladas más jóvenes, tienen longitudes de hasta solo 3 km, y morfologías de tipo bloques. El Cordón Fisural Oriental (CFO, 10 km de largo), corresponde un sistema de fisuras ubicado en sector este del CVL, compuesto por numerosos conos piroclásticos en orientación NE. Las coladas del CFO presentan longitudes de hasta 10 km de largo, con morfologías de tipo bloques. En esta zona es donde han ocurrido las erupciones históricas del complejo. La petrografía de todas las unidades del CVL, se mantiene muy uniforme en el tiempo. Los parámetros eruptivos que controlaron la formación de estas coladas de lava no históricas fueron determinados gracias a un estudio detallado de sus morfologías, dimensiones y petrografía, obteniendo variaciones de estos valores en el tiempo a partir de mediciones y muestreos a diferentes distancias de la fuente de emisión. Esto se realizó con análisis dimensional de las coladas de lava, basado en un flujo de tipo Herschel-Bulkley, Los resultados obtenidos indican que las coladas de lava más antiguas del cono principal presentaron altas tasas eruptivas (hasta 433 m3 s-1), lo que junto al alto volumen emitido (~0,1 km3), permitieron la formación de largas coladas; estos valores habrían ido disminuyendo, a medida que se formó el estratovolcán, hasta el punto en que las últimas coladas solo alcanzan un par de kilómetros de largo, con tasas eruptivas del orden de 2 m3 s-1, y volúmenes de solo 0,01 km3. De acuerdo a las variaciones observadas, las dimensiones de las coladas estarían estrictamente ligadas a la tasa eruptiva y a los volúmenes emitidos. Estos parámetros estarían, a su vez, determinados por la presión que ejerce la masa de material acumulado sobre la cámara magmática, debido a la formación del estratovolcán: cuando mayor es el volumen del volcán, menores serán las tasas eruptivas y volúmenes generados. Por lo que luego de la superposición de las últimas unidades en el estratovolcán, los magmas habrían perdido la capacidad de ascender por el conducto principal, por lo que la actividad volcánica reciente se estaría llevando a cabo en el CFO, por las facilidades que presenta el sistema de fallas.

No description available.

Effusive volcanic eruptions repave landscapes rapidly with lava flows, resetting the underlying landscape and ecosystem. The unique physical properties of lava pose interesting challenges for recovery, as lava flows can be highly permeable while lava itself is dense, sterile, and generally inhospitable towards life. This dissertation examines two aspects of landscape recovery following lava flow emplacement: (1) hydrologic adaptation of surface and groundwater to recent volcanism and (2) plant colonization of young lava flows. I examine two sites in the central Oregon Cascades: the c. 3 ka Sand Mountain volcanic field (SMVF), located in the headwaters of the McKenzie River, a critical water resource for the state of Oregon, and the c. 1.5 ka Collier Cone lava flow, originating on the north flanks of North Sister volcano. My investigation of the SMVF and upper McKenzie River watershed reveals a complex volcanic history with profound impacts on the configuration and short-term discharge of the McKenzie River: lava flows from the SMVF and other Holocene vents have buried, dammed, and altered the path of the McKenzie River. Moreover, given the large groundwater contribution from the SMVF to the McKenzie River, I estimate that SMVF activity caused McKenzie River discharge in present-day Eugene, Oregon to decrease by up to 20% for days to months at a time; future regional mafic volcanic activity could have a similar impact. The SMVF and the Collier Cone lava flow are notable for the juxtaposition of barren exposed lava and mature forests on the same or similarly aged lava flows. I use a combination of LiDAR analysis, field observations, and soil characterization to examine soil and vegetation at these two sites and find that the presence of an external soil source greatly facilitates plant establishment, growth, and survival. Here, external soil sources are syn- or post-eruptive tephra (SMVF) or flood-borne deposits (Collier Cone lava flow). External soil appears to provide a substrate for plants to grow in along with key nutrients and sufficient moisture; overall, external soil sources are key for the initial recovery following an effusive volcanic disturbance. This dissertation includes co-authored material submitted for publication.

No description available.