No description available.

The Standard Model has been very successful over the last few decades in its agreement with experimental evidence; however there are some remaining puzzles in our understanding of the Universe which have yet to be solved. Even if the Higgs boson and Super Symmetry are discovered, questions still arise, such as why Nature is primarily made of matter when antimatter should have been produced in equal amounts at the beginning of the Universe, why the fundamental particles have the mass hierarchy that they do, what the nature of dark matter is, or whether or not quarks and leptons are themselves made of constituent parts, just to name a few. Theories Beyond the Standard Model attempt to tackle these questions, and also provide alternative explanations for electroweak symmetry breaking in case the Higgs mechanism in the Standard Model contradicts what is observed. The ATLAS detector was built to discover new physics from high-energy proton-proton collisions delivered by the Large Hadron Collider and to probe the electroweak scale with hard interactions at energies near ~1 TeV. While searching for new physics processes occurring at a much higher invariant mass than available at previous colliders, understanding the performance of the detector is crucial, especially during the first few months of running. This thesis presents a motivation for using dimuons to search for new physics in early ATLAS data, a measurement of the Z0/γ ->μμ cross section as a first test of Standard Model theoretical predictions at √s =7 TeVqqμμ, and finally a search for new physics via a four-fermion contact interaction in the dimuon channel (qqμμ) using the full 2010 data set.

Student Number : 9907276D - MSc Dissertation - School of Animal, Plant and Environmental Sciences - Faculty of Science / The broad aim of this study was to measure the ecosystem repair of the Sabie River (which traverses through both the grassland and savanna biomes) riparian environment in Mpumalanga, South Africa, in response to the clearing of alien plants by the Working for Water (WfW) alien plant clearing programme. This was done in order to assess the effectiveness of the WfW clearing on the Sabie River riparian plant community composition and associated environmental factors. Although “effectiveness” can be assessed in various ways, in this study it included determining whether there was a reduction in the invasion intensity (defined as the percentage aerial cover of woody alien plants) after clearing. This broad aim was achieved by studying the impacts of the WfW alien plant clearing programme, as well as the invasion of alien plants, on the plant species composition, diversity and vegetation structure of riparian ecosystems on the Sabie River. Hence, in 2005 40 modified Whittaker nested plots were sampled. The impacts on the Sabie River riparian environment were also assessed by measuring various environmental variables that are likely to change as a result of clearing, such as the ground cover (percentages of exposed soil, rock, litter, herbaceous vegetation and grass), as well as various soil chemical and physical properties. Twenty plots were surveyed along the Sabie River in the Hazeyview region (savanna biome), ten in the Sabie region (grassland biome) and ten in the Graskop region (grassland biome). The response of the Sabie River riparian community to invasive alien plant clearing by WfW (and the alien plant invasion itself) was also assessed over time, by comparing the 2005 study with one done in 1996, which used the same plots. In 2005, a cumulative total of 282 species were found, 222 (79%) of which were indigenous and 60 (21%) alien. The grassland sites had a higher cumulative total of 222 species compared with the 171 species in the savanna sites. A total of 112 (39%) species were common between the biomes, 86 (30%) of which were indigenous and 26 (9%) alien. At the 1000 m2 scale, the indigenous species richness (32.4 ± 1.4 (S.E.)) was significantly higher than the alien species richness (12.0 ± 0.5) (P < 0.001). Of the 60 alien species, 17 (28%) were shrubs and 15 (25%) trees. The grassland sites were more species rich at the 1000 m2 scale (48.8 ± 1.8) and diverse at the 100 m2 scale (Simpson’s index of alpha diversity of 0.90 ± 0.01) than the savanna sites (species richness of 40.0 ± 2.1 and alpha diversity of 0.85 ± 0.02; P = 0.003 for species richness and P = 0.04 for alpha diversity). The Sabie sites were more species rich at the 1000 m2 scale (52.6 ± 2.8) than the Graskop sites (45.0 ± 1.4) (P = 0.12). The higher species richness in the Sabie region contributed to the higher total species richness in the grasslands relative to the savanna sites. At the 1000 m2 scale, the overall beta diversity (Sorenson’s coefficient of community) between the biomes was 0.57, and the species complementarity (the Marczewski-Steinhaus distance) between the biomes was 0.60, indicating that the biomes were not that similar in terms of species composition. Even though the grassland was more rich and diverse in terms of species than the savanna, the overall relative abundances of plant species in each biome was very similar (species evenness (Simpson’s measure of evenness), at the 100 m2 scale, of 0.52 ± 0.03 in the grassland and 0.51 ± 0.03 in the savanna; P = 0.74). The savanna tended to have a higher degree of invasion intensity (aerial cover of woody alien plants of 34.4 ± 4.6% compared to 29.4 ± 4.5% in the grassland; P = 0.44), possibly due to its position lower in the catchment, and hence a sink for upstream alien plant propagules. It was hypothesized that higher plant species richness and/or diversity should enhance community resistance to alien plant invasions, in both the grassland and savanna biomes. In the Sabie (grassland) region, there was a negative correlation between the indigenous and alien species richness, thus indicating that the Sabie region plant community may have been more resistant to the invasion of alien plants than the other two regions. Therefore, the hypothesis was not rejected for the Sabie region. On the other hand, in the Graskop (grassland) and Hazeyview (savanna) regions, there were positive correlations between the indigenous and alien species richness, thus indicating that these plant communities may not have been as resistant to the invasion of alien plants. Therefore, the hypothesis was rejected for both the Graskop and Hazeyview regions. When considering the biome scale, the hypothesis was not rejected as the increase in total species richness with increasing invasion intensity in the grassland (which was more diverse than the savanna) indicated that it may have been more resistant to the invasion of alien plants than the savanna, which had a total species richness that decreased with increasing invasion intensity. In 2005, exposed soil, litter and grass covers tended to be slightly higher in the savanna (14.4 ± 1.6%; 43.5 ± 3.0%; 21.8 ± 1.7% respectively) than in the grassland (12.1 ± 2.5%; 43.2 ± 4.2%; 20.1 ± 2.3% respectively) (P = 0.43, 0.96 and 0.56 respectively). Rock and herbaceous covers were higher in the grassland (4.3 ± 1.6% and 20.3 ± 1.7% respectively) than in the savanna (0.8 ± 0.2% and 19.5 ± 2.2% respectively), but only rock cover was significantly different (P = 0.04) (P = 0.76 for herbaceous cover). These patterns in ground cover may have been a response to the slightly higher invasion intensity in the savanna. The hypothesis that the lower the degree of alien plant invasion, the higher the understorey vegetation cover, which may result in reduced cover of exposed soil and litter, in both the grassland and savanna biomes, was not rejected as the grassland tended to have a lower degree of alien invasion (although not significant), a higher cover of herbaceous vegetation, and corresponding lower covers of exposed soil and litter. The biomes (in 2005) did not differ significantly in soil pH (grassland pH: 4.6 ± 0.1; savanna pH: 4.8 ± 0.1; P = 0.34). However, the grassland soils were generally more fertile than the savanna soils, i.e. higher organic matter (4.5 ± 0.2% versus 3.3 ± 0.4%; P = 0.01) and total nitrogen (0.3 ± 0.02% versus 0.2 ± 0.02%; P = 0.03). The concentrations (mg/l) of most of the nutrients were also higher in the grassland. The lower fertility of the savanna soils may have been related to the higher litter cover of the savanna immobilizing a larger amount of available nutrients than the grassland; another possibility may have been slower rates of soil organic matter decomposition in the slightly cooler (higher altitude) grassland regions. The soils of the grassland sites tended to be more compacted (0.8 ± 0.1 kg/cm2) (but not significantly) than those of the savanna sites (0.7 ± 0.1 kg/cm2) (P = 0.43), and the savanna plots were on significantly steeper ground (12.8 ± 1.7º) than the grassland plots (4.8 ± 1.1º) (P < 0.001), which may have also contributed to lower fertility through greater leaching and erosion losses. From the detrended correspondence analysis (DCA) of the species by plot data, there were no distinct plant communities separating out between the biomes and regions. This is probably because the Sabie River riparian environment essentially supports a riparian forest/woodland, rather than reflecting the species typically found in the adjoining (more upland) grasslands and savannas. Hence, the species composition of the riparian environment was fairly uniform throughout the study area. The canonical correspondence analysis (CCA), which also incorporates the environmental variables, showed that altitude, exposed soil cover, soil pH, organic carbon content and slope steepness were the variables that most closely (and significantly) correlated with the species composition, and two of these variables relate directly to soil fertility, and the other three are indirectly related to soil fertility. Of the original “treatments” of the 1996/1997 study, namely (A) biome (grassland versus savanna), (B) invasion intensity (high (> 50%) versus low (< 50%)), and (C) clearing (cleared versus uncleared), the legacy of the latter two did not persist over time, as there was little or no clear overall relationship between the 1996 and 2005 data when analysed by ANCOVA. The cumulative total species richness sampled in the 40 plots increased from 163 species in 1996, to 282 in 2005 (42% increase). Mean species richness (at the 1000 m2 scale) was 24.1 ± 1.0 in 1996 and 44.4 ± 1.5 in 2005 (P < 0.001). Trees increased from 28 species in 1996 to 46 in 2005 (39% increase), shrubs from 44 to 82 (46%), herbaceous plants from 71 to 121 (41%), and grasses from 20 to 33 (39%). However, even though the species richness of each growth form increased over time, the proportion of each growth form remained approximately the same, i.e. in 1996, 17% of the species were trees, 27% shrubs, 44% herbaceous and 12% grasses; whereas in 2005, 16% were trees, 29% shrubs, 43% herbaceous and 12% grasses. The greatest increase over time was for category 1, 2 and 3 weed species, namely 25 in 1996 to 50 in 2005, a 50% increase. Although mean alpha diversity was higher in 2005 (0.9 ± 0.01 compared to only 0.3 ± 0.03 in 1996 (at the 100 m2 scale); P < 0.001), overall beta diversity over time (a change from 1996 to 2005) was relatively low, indicating a small change in overall species composition, despite the increase in species richness. The invasion intensity (percentage aerial cover of woody alien plants) was similar between the years, i.e. 30.0 ± 4.6% in 1996 and 31.9 ± 3.2% in 2005 (P = 0.73). When comparing the invasion intensity between the three original treatments over time, the invasion intensity of the 1996 grassland and savanna plots remained unchanged. The invasion intensity of the 1996 high invaded plots also remained unchanged over time, however the low invaded plots had a significantly higher invasion intensity in 2005 (P = 0.004). The invasion intensity of the 1996 uncleared plots remained unchanged over time, whereas the cleared plots had a significantly higher invasion intensity in 2005 (P = 0.03). These results clearly show that the legacy of the original invasion intensity and clearing treatments measured in the 1996/1997 study did not persist over time, whereas the inherent differences between the biomes did. The hypothesis that higher plant species richness and/or diversity should enhance community resistance to alien plant invasions was rejected, as both the 1996 and 2005 plant communities were not that resistant to the invasion of alien plants, even though there was a significantly higher species richness and diversity in 2005 than in 1996. It is concluded that because of both the similar growth form composition and invasion intensity over time, the WfW clearing efforts are not succeeding in the primary aim of controlling aliens, particularly woody alien species. However, there was a considerable decrease in the aerial cover of large alien plants, namely (a) alien plants > 5 m decreased from 15.8 ± 4.1% in 1996 to 5.8 ± 1.2% in 2005 (P = 0.02), and (b) those between 2 – 5 m tended to decrease from 13.3 ± 2.8% in 1996 to 11.1 ± 2.4% in 2005 (P = 0.55). However, these decreases were balanced by a considerable increase in the aerial cover of alien plants < 2 m in height, which increased from 3.9 ± 1.0% in 1996 to 15.0 ± 2.1% in 2005 (P < 0.001). This therefore showed that the WfW clearing programme is succeeding, to some extent, in removing most of the larger alien plants but not in controlling the regenerating plants, which recover through post-clearing resprouting and/or newly established seedlings. Exposed soil, rock and litter covers were higher in 2005 (13.3 ± 1.5%; 2.5 ± 0.8%; 43.3 ± 2.5% respectively) than in 1996 (2.1 ± 0.5%; 0.9 ± 0.3%; 16.4 ± 2.7% respectively) (P < 0.001 for soil and litter covers, and 0.07 for rock cover). Herbaceous and grass covers were significantly higher in 1996 (47.8 ± 2.8% and 32.8 ± 2.6% respectively) than in 2005 (20.0 ± 1.4% and 20.9 ± 1.4% respectively) (P < 0.001 for herbaceous and grass covers). These differences in the ground covers between the years may have partially been a response to the major February 2000 flood event, which cleared a large proportion of the vegetation, resulting in much greater rates of erosion and deposition of soils. The WfW clearing operations also removed a significant proportion of the vegetation, and disturbed much that remained, thus modifying the environment. The increase in litter cover may have also been due to the slightly higher invasion intensity in 2005 than in 1996. Soil pH remained unchanged over time (both years had a pH of 4.7 ± 0.1; P = 0.99), indicating that pH was unaffected by the invasion and subsequent clearing of alien plants, as well as the 2000 flood event which moved a tremendous amount of sediment. The hypothesis that the lower the degree of alien plant invasion, the higher the understorey vegetation cover, in both 1996 and 2005, was not rejected as the plots in 1996 had a lower degree of alien invasion (although not significant), a higher cover of herbaceous vegetation, and corresponding lower covers of exposed soil and litter. Along the Sabie River, the alien tree and shrub species with the greatest densities were Rubus cuneifolius (American bramble) (1828 plants/ha), Lantana camara (Lantana) (1760), Solanum mauritianum (Bugweed) (838), Indigofera macrophylla (640), Eucalyptus grandis (Saligna gum) (560), Caesalpinia decapetala (Mauritius thorn) (403), Agrimonia odorata (Agrimonia) (220), Lilium formosanum (St. Joseph’s lily) (218), and Populus x canescens (Grey popular) (125). Focusing the clearing efforts on these species will help to reduce the frequency of re-invasions, reduce costs, and increase ease of clearing. The primary aim of the WfW programme is to increase water supplies by controlling woody alien plants. Therefore, it is concluded that the WfW clearing along the Sabie River has been partially successful, as there has been a significant decrease in the invasion intensity of large (> 5 m) alien trees (which tend to have the highest transpiration rates) over time from 1996 to 2005. In 1996, these large alien trees were represented mainly by Eucalyptus spp. However, the WfW programme was not effective in terms of ecosystem repair, as the invasion intensity increased slightly from 1996 to 2005, largely as a result of the significant increase in the aerial cover of smaller alien shrubs (< 2 m). If left unchecked, these will probably in time result in even higher levels of invasion intensity when the individual plants increase in size and cover. Furthermore, the growth form composition remained relatively unchanged over time, and more than half of the alien species found in 2005 were tree and shrub species. Therefore, little or no ecosystem repair has occurred along the Sabie River. In order to improve the effectiveness of the WfW programme, various detailed recommendations are included, which largely revolve around improvements in follow-up treatments.

A search for new heavy resonances in two-jet final states is described in this thesis. The data were collected by the ATLAS detector proton-proton collisions at sqrt(s) = 7 TeV and correspond to a time-integrated luminosity of 6.1 pb−1. The background-only hypothesis was tested on the observed data using BumpHunter test statistic. Consistency was found between the observed data and the background-only prediction. No resonant features were observed. A Bayesian approach using binned maximum likelihood was used to set upper limits on the product of cross section and detector acceptance for excited-quark (q*) production as a function of q* mass. At 95% credibility level (CL), the q* mass in the interval of 0.50 TeV < mq* < 1.62 TeV is excluded, extending the reach of previous experiments.

A search for new heavy resonances in two-jet final states is described in this thesis. The data were collected by the ATLAS detector proton-proton collisions at sqrt(s) = 7 TeV and correspond to a time-integrated luminosity of 6.1 pb−1. The background-only hypothesis was tested on the observed data using BumpHunter test statistic. Consistency was found between the observed data and the background-only prediction. No resonant features were observed. A Bayesian approach using binned maximum likelihood was used to set upper limits on the product of cross section and detector acceptance for excited-quark (q*) production as a function of q* mass. At 95% credibility level (CL), the q* mass in the interval of 0.50 TeV < mq* < 1.62 TeV is excluded, extending the reach of previous experiments.

This thesis aims to analyse different Monte Carlo methods when applied to the problem of option pricing. Closer attention is paid to three variance reduction techniques, namely control variathes, importance sampling and antithetic variables, and two different approaches, least-squares Monte Carlo and quasi-Monte Carlo methods. The detailed analysis of the differences and improvements is done on a problem of plain vanilla option pricing. At the end the methods are each applied to valuation of different exotic options.

No description available.

The Fremont tradition developed on the northern Colorado Plateau and eastern Great Basin between A.D. 1 and A.D. 1350 (Talbot 2000a). Research on exotics in the Fremont area, specifically turquoise and Olivella shell, has been sporadic until recently (Hughes and Bennyhoff 1986; McDonald 1994; Janetski 2002). In this thesis, I present new data on Olivella and turquoise artifacts found throughout the Fremont region, including the Parowan Valley sites, Nephi Mounds, and Kay's Cabin, as well as a spatial distribution of Olivella and turquoise in the Fremont area. I performed microprobe analysis on blue-green artifacts from Kay's Cabin and found most are turquoise, although other minerals including variscite, azurite, malachite, and possibly chrysocolla are also present. Also, various experimental methods were used to chemically characterize a turquoise artifact from Parowan Valley (see Appendix A). I analyzed over 350 Olivella artifacts (see Appendix B) and examined modern Olivella shells; therefore, I provide a discussion of the details and differences between the O. biplicata and O. dama species. Through testing Janetski's (2002) trade fair model, I readdress the question of whether or not Olivella and turquoise were distributed across the Fremont region via directional or down-the-line exchange. My research supports Janetski's model and shows that Fremont exotic exchange moved directionally, with Olivella and turquoise artifacts concentrated at central sites on the Fremont landscape. I also explore the possibility that the exchange of Olivella and turquoise to the Fremont area was conducted through different networks. It appears, based on high numbers of turquoise at certain sites and high frequencies of Olivella artifacts at other sites, that these ornaments were not traded together. I examine whether exotic artifacts were differentially distributed among sites in Parowan Valley and within the specific sites and I observed that Olivella and turquoise are most often associated with living areas.

A atividade de restauração florestal é freqüentemente realizada em áreas degradadas, ocupadas por gramíneas exóticas invasoras, e o controle destas plantas é fator determinante no sucesso da restauração. Esta pesquisa tem o objetivo de testar intervenções para controle da gramínea exótica invasora Urochloa decumbens Stapf. em área de restauração florestal, com plantio de mudas nativas em área total. O delineamento utilizado foi o de blocos com parcelas subdivididas. Os tratamentos aplicados nas parcelas foram: 1. Não inversão de solo (R) e 2. Com inversão de solo por gradagem (G). Os tratamentos aplicados nas subparcelas foram: 1. Aplicação de herbicida na instalação e nas manutenções (H), 2. Plantio de feijão de porco (Canavalia ensiformes DC.) com aplicação de herbicida na instalação e nas manutenções só roçagem (H+FP), 3. Plantio de feijão de guandu (Cajanus cajan L.) com aplicação de herbicida na instalação e nas manutenções só roçagem (H+FG), 4. Plantio de feijão de porco (Canavalia ensiformes DC.) na instalação e nas manutenções só roçagem (FP), 5. Plantio de feijão de guandu (Cajanus cajan L.) na instalação e nas manutenções só roçagem (FG), 6. Roçagem na instalação e nas manutenções (sem aplicação de herbicida e sem plantio de adubos verdes) (s/Hs/AV). O desenvolvimento da gramínea foi avaliado pela altura e porcentagem de cobertura no solo e o desenvolvimento das mudas pela altura, área de copas e mortalidade. As analises estatísticas foram realizadas pelo pacote estatístico SAS. O experimento permitiu concluir que, no período entre plantio e a primeira manutenção (realizada 3 meses após o plantio) as coberturas vivas na interação R(H+FP) e R(H+FG) diminuíram a porcentagem de cobertura no solo de U. decumbens em relação ao tratamento R(s/Hs/AV) e os tratamentos (H+FP) e (H+FG) diminuíram a altura da U. decumbens no primeiro mês em relação ao tratamento (s/Hs/AV). Após a primeira manutenção, apenas o tratamento (H) diminuiu a porcentagem de cobertura no solo de U. decumbens e a altura desta gramínea em relação a todos os demais. Nas variáveis referentes ao desenvolvimento das mudas, apenas a variável área de copas apresentou diferença significativa nas interações entre os tratamentos R(H) e R(s/Hs/AV) 7 meses após o plantio e R(H) em relação a todos os demais 9 meses após o plantio, sendo que o R(H) apresentou maior área de copas. Neste experimento, o uso de adubos verdes em área de restauração florestal não melhorou o desenvolvimento das mudas plantadas. O tratamento que promoveu menor porcentagem de cobertura no solo de U. decumbens, menor altura de Urochloa decumbens Stapf. e mudas com maior área de copas foi o que teve aplicação de herbicida na instalação e nas manutenções (H). / The activity of forest restoration is often performed in areas covered by exotic grasses. In this way, the weed control of these plants is a determining factor in the success of restoration. This project aims to test different interventions for Urochloa decumbens Stapf. control in an area of forest restoration with seedlings planting in total area. The design adopted was split plot treatments divided in blocks, with each plot with different kind of soil tillage systems: 1. tillage (no soil movement) and 2. Harrowing (ground motion); and subplots with: 1. herbicide application in the installation and during maintenance (H); 2. herbicide application and planting of bean (Canavalia ensiformis DC.) in the installation and maintenance on mowing (FP + H); 3. herbicide application and planting beans (Cajanus cajan L.) in the installation and maintenance on mowing (H + FG); 4. planting bean (Canavalia ensiformis DC.) in the installation and maintenance on mowing (FP), 5. planting bean (Cajanus cajan L.) in the installation and maintenance on mowing (FG); and 6. no herbicide application nor planting green manure in the installation and the maintenance on mowing (s / Hs / AV). The grass height and percentage of occupation in of the soil was measured, as well the height, canopy area and mortality of seedlings, all of them analyzed by the SAS statistical package. In the period between planting and first maintenance (3 months), the living roofs in the interaction R (H + FP) and R (H + FG) controlled the percentage of invasive exotic grasses in the soil, and the treatments (H + FP) and ( H + FG) controlled the height of grasses in the first month. After the first maintenance, only the treatment (H) controlled the grasses in percentage of occupancy in the soil and height. Regarding the variables referred to the seedlings, only the canopy area showed a significant difference between treatments (H) and (s / Hs / AV) 7 months after planting and the (H) treatment showed a difference among all others, 9 months after planting,, as well its showed the biggest area. In this experiment the use of green manure in the area of forest restoration did not improve seedling growth. The (H) treatment was the one that promotes the Urochloa decumbens Stapf. control for a longer time and the seedlings with the largest canopy area.

A flora of the 3800 ha Rocky Fork Tract in northeast Tennessee produced 749 species of which 19 were on the Tennessee Rare Plant List and 34 were on the Cherokee National Forest Species Viability List with 87 county records from Greene County and 217 from Unicoi County. Rare species were particularly numerous in the Cyperaceae and Orchidaceae. The tract serves as a refuge for several regionally uncommon species by supporting either large populations or metapopulations of these species. Exotic species comprised 15% of the flora and were most common in the Fabaceae and Poaceae. The most unique habitat was a heath bald dominated by Rhododendron catawbiense with abundant Xerophyllum asphodeloides in the herbaceous layer. While species richness was relatively high compared to regional sites of comparable area, diversity was limited by the absence of high elevation spruce-fir communities and the paucity of wetlands.