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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Standard model and exotic physics with the top quark at ATLAS

Bernard, Clare Sullivan 12 March 2016 (has links)
The top quark is the most massive fundamental particle in the Standard Model of particle physics. Only experimentally observed in 1995, it can be used as a precise test of Standard Model predictions, and it could lend insight to the problem of what lies beyond the Standard Model. This thesis presents a measurement of top-quark pair production using data collected at a center-of-mass energy √s=7 TeV in 2011, and a search for production of vector-like quarks using data collected at √s=8 TeV in 2012. Both datasets were recorded by the ATLAS detector, a multipurpose proton-proton collider located at the CERN LHC outside of Geneva Switzerland. The top-quark pair production cross-section is measured as a function of four different variables and the results are presented as normalized, differential spectra. The variables considered are the transverse momentum of the top quark, and the mass, rapidity, and transverse momentum of the top-quark pair system. Events are selected in the lepton+jets channel, and the measured spectra are corrected for detector resolution and efficiency. The final results are compared with predictions from various Monte Carlo generators, theoretical calculations and proton parton distribution functions and found to be in reasonable agreement. Data is found to be softer than all predictions, particularly for high values of top-quark transverse momentum and the top-quark pair invariant mass. The search for vector-like quarks focuses on new heavy quarks that decay with a large branching ratio to a Z boson and a third generation Standard Model quark. Events are selected with at least two leptons (electrons or muons), and two of the leptons are required to reconstruct a Z boson with high transverse momentum. No significant excess of events is observed above the Standard Model prediction. Upper limits on the masses of vector-like T and B quarks are derived for various branching ratio hypotheses.
352

Top management commitment and Empowerment of employees in TQM implementation

Litie Njie, Thaddeus, Teku Fon, Linus, Awomodu, Gbolahan January 2008 (has links)
Top management commitment and employees empowerment is one of the most important and vital principle in total quality management, because it is often assumes to have a strong relationship with customer satisfaction. In TQM implementation top management commitment in creating an organizational climate that empowers employees is very imperative. Thus, this can be achieved with top management commitment in training employees and giving employees opportunities to be responsible for the quality of their work. TQM strategy brings about a turn around in corporate culture as compared to the old traditional system of management in which the top management simply give orders and the employees merely obey them. In this study we’ll show that TQM objective of quality improvement and customer satisfaction can be better achieve if the top management are committed to empower employees to be responsible for the quality of their work and also empowerment in relation to decision making authority and process. We’ll as well show that empowerment in TQM brings about a flattened organizational chart where there is a shared responsibility between the managers and the employees. Despite some arguments put forward by some researchers to criticize employee empowerment, we’ll as well show that employees’ empowerment and improved level of job satisfaction can be facilitated by top management leadership and commitment to the goal of customer satisfaction in TQM organization. / Uppsatsnivå: D
353

Evidence for the production of a Higgs boson in association with two top quarks with the ATLAS detector

Raine, John January 2018 (has links)
In this thesis, the search for the production of the Higgs boson in associationwith two top quarks is presented. The main focus of this work is on the analysis optimised for the decay of the Higgs boson to a b-quark pair. The analysis is performed using 36.1 fb−1 of ppcollision data at a centre of mass energy sqrt(s)=13 TeV collected by the ATLAS detector at the Large Hadron Collider during 2015 and 2016. The signal strength of ttH in relation to the Standard Model prediction for a Higgs boson with a mass of 125 GeV is measured to be mu(ttH) = 0.87 +0.64−0.61, with signal strengths greater than 2.0 excluded at the 95% confidence level. The combination of this analysis with searches targeting additional Higgs boson decay modes is subsequently presented. The measured signal strength in relation to the Standard Model prediction is mu(ttH) = 1.2 +/-0.3. This correspondsto an observed (expected) significance for ttH of 4.2sigma (3.8sigma), constituting evidence for the ttH production mode. Finally, a study into the ability to observe and model the colour connection of b-quarks in ttH(bb) and ttbar+jets events is presented. The jet pull angle observable is used to investigate the effect of colour connection on jet substructure. Such an observable is found to be sensitive to the underlying colour structure in events, showing differences between b-quarks which decay from a colour singlet in comparison to a colour octet. However, the effect is found to be small and a larger dataset is required to measure the effect in ttH events.
354

Análise de métodos para criação de vocabulário de gestos para aplicações em superfície multi-toque. / Analysis of methods for creation of vocabulary of gestures for multi-touch surface\'s applications.

Marylia Gutierrez 11 March 2015 (has links)
Este trabalho apresenta um estudo na área de mesas interativas e uso de gestos como forma de entrada. Primeiramente é analisado um conjunto representativo de métodos de elicitação existentes que geram um vocabulário de gestos para aplicações de superfícies multitoque, como mesas interativas. Algumas das características analisadas são: custos, clareza de informações e se avalia o vocabulário final criado. São obtidos, assim, os pontos positivos e negativos dos métodos. Em seguida, as informações obtidas na análise feita, juntamente com outras informações e definições na área, permitiram a criação de um metamétodo. Esse metamétodo pode ser utilizado como base para criação de métodos, pois define desde a escolha de quais usuários utilizar nos testes até o desenvolvimento da aplicação utilizando o vocabulário de gestos criado. / This work details a study in the area of interactive tables and the use of gestures as input. First, a representative set of elicitation methods that create a vocabulary of gestures for multitouch surface application, such as interactive tables, are analyzed. Some of the characteristics analyzed are: costs, clarity of informations and whether the final vocabulary of gestures is evaluated afterwards. This way the pros and cons of the methods are established. The insights obtained in the analysis, along with other information and definitions on the area, allowed the creation of a metamethod. This metamethod can be used as a basis for creating other methods, since it defines all the steps required, from the selection of users for the test to the development of the application that will use the vocabulary of gestures created.
355

Efici?ncia da recupera??o ambiental de ?reas antropizadas pela minera??o de ferro do Complexo Caraj?s - PA / Efficiency of environmental rehabilitation of areas disturbed by mining iron Complex Caraj?s - PA

GON?ALVES, Fernando Soares 16 April 2012 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-04-11T20:50:25Z No. of bitstreams: 1 2012 - Fernando Soares Gon?alves.pdf: 1312529 bytes, checksum: f74571a02ea2e60ea594e27896515023 (MD5) / Made available in DSpace on 2017-04-11T20:50:25Z (GMT). No. of bitstreams: 1 2012 - Fernando Soares Gon?alves.pdf: 1312529 bytes, checksum: f74571a02ea2e60ea594e27896515023 (MD5) Previous issue date: 2012-04-16 / CAPES / Mining activities have a direct influence on economic development, which directly affects the gross domestic product (GDP), mainly in developing countries. The environmental interference provided by the mining activities can vary in intensity according to the mineral exploited, but they are always punctual activities. This study was conducted in the mineral province of Caraj?s, PA, in areas revegetated post mining iron ore, and to evaluate the processes of vegetation arising from revegetation of barren slopes, starting from the initial hypothesis that signed the revegetation of slopes of waste in the mining of iron using cocktails of seed species in the rainforest and savanna Metal?fila can act as facilitators of natural succession and conditioners as the substrate. The second hypothesis is that signed the removal, storage and return of surface soil organic horizon ("topsoil") after the operation by open pit mines have an essential role in the revegetation process, because they already provide quantitative and qualitative characteristics that reflect the communities previously existing in the area. In this work were highlighted four areas of study, three areas undergoing revegetation and an area with the presence of primary forest. The variables analyzed were phytosociology, photosynthetically active radiation, chemical quality of the stock of litter, soil fauna and soil fertility. The results indicate that the revegetation processes used, promoted the formation of a plant community which facilitates the process of succession over time, as many of the species used in the cocktail of seeds of the CCI and workshop areas are being replaced by species more adapted to conditions of each site. In the area called Hoppe, the herbaceous species that colonized the area are being replaced by shrub and tree species. The quality of the provided information able to litter cluster areas of studies according to the nutrients present in the litter, the areas being divided into Workshop CCI and the concentrations of lignin, cellulose, P and Mg, while areas were grouped Hoppe and Mata as a function of P and N fractions present in the twigs and leaf litter. But the use of soil fauna indicated that the groups Collembola and Formicidae will be extremely important for monitoring the quality of sites over time. From these results it was concluded that the use of biotic and abiotic indicators in studies of recovery of mined areas should be thoroughly studied and documented, they offer attributes able to understand developments in the recovery process. / As atividades de minera??o t?m influencia direta sobre o desenvolvimento econ?mico, afetando diretamente o produto interno bruto (PIB), principalmente dos pa?ses em desenvolvimento. As interfer?ncias ambientais proporcionadas pelas atividades de minera??o podem variar de intensidade de acordo com o mineral explorado, mas sempre s?o atividades pontuais. O presente estudo foi realizado na prov?ncia mineral de Caraj?s-PA, em ?reas revegetadas p?s minera??o de min?rio de ferro, tendo como objetivo avaliar a forma??o vegetal oriunda dos processos de revegeta??o de taludes de est?ril, partindo da primeira hip?tese firmada que a revegeta??o dos taludes de est?ril em ?rea de minera??o de ferro utilizando coquet?is de sementes de esp?cies pertencentes a savana metal?fila e floresta ombr?fila podem agir como facilitadores da sucess?o natural e como condicionadores do substrato. A segunda hip?tese firmada ? que a retirada, armazenamento e retorno do horizonte org?nico superficial do solo (?topsoil?) ap?s a explora??o por minera??es a c?u aberto t?m fundamental papel no processo de revegeta??o, por j? apresentar caracter?sticas quantitativas e qualitativas que refletem as comunidades anteriormente existentes na ?rea. Neste trabalho foram demarcadas quatro ?reas de estudo, sendo tr?s ?reas em processo de revegeta??o e uma ?rea com presen?a de mata prim?ria. As vari?veis analisadas foram fitossociologia, radia??o fotossinteticamente ativa, qualidade qu?mica do estoque de serrapilheira, fauna do solo e fertilidade do solo. Os resultados obtidos apontam que os processos de revegeta??o utilizados, promoveram a forma??o de uma comunidade vegetal que viabilize o processo sucessional ao longo do tempo, pois muitas das esp?cies utilizadas no coquetel de sementes das ?reas CCI e Oficina est?o sendo substitu?das por esp?cies mais adaptadas ?s condi??es de cada s?tio. Na ?rea denominada Hoppe, as esp?cies herb?ceas que colonizaram a ?rea est?o sendo substitu?das por esp?cies arbustivas e arb?reas. A qualidade da serrapilheira forneceu subs?dios capazes de agrupar as ?reas de estudos em fun??o dos nutrientes presentes na serrapilheira, sendo as ?reas CCI e Oficina agrupadas em fun??o das concentra??es de lignina, celulose, P e Mg, enquanto que as ?reas Hoppe e Mata ficaram agrupadas em fun??o do Ca e N presente nas fra??es galhos e folhas da serrapilheira. J? a utiliza??o da fauna do solo indicou que os grupos Collembola e Formicidae ser?o de extrema import?ncia para o acompanhamento da qualidade dos s?tios ao longo do tempo. A partir destes resultados foi poss?vel concluir que a utiliza??o de indicadores bi?ticos e abi?ticos em estudos de recupera??o de ?reas mineradas devem ser amplamente estudados e documentados, pois oferecem atributos capazes de compreender a evolu??o nos processos de recupera??o.
356

Observation of the Standard Model Higgs boson produced in association with a pair of top quarks at $\sqrt{s} = 13 \, \text{TeV}$ with the ATLAS experiment at the LHC with emphasis on the decay of the Higgs boson into a $b\bar{b}$-pair in the single-lepton channel

Mellenthin, Johannes Donatus 21 August 2019 (has links)
No description available.
357

READ 180 Evaluation: Balanced Literacy in a Low-Income, Underperforming Urban High School

Lombardi, Daniel 01 January 2015 (has links)
This study investigated the effectiveness of the READ 180 balanced literacy program in addressing the problem of low reading achievement among urban minority high school students. Research has shown low reading achievement to negatively impact academic and economic success. Holdaway's theory of natural literacy, which suggests reading instruction should be purposeful and realistic, supports READ 180 as a remedial intervention. The specific purpose of the study was to evaluate READ 180 in relation to improving classroom reading achievement, standardized language arts test scores, and graduation rates among students in a low-income, high-minority urban high school. Subjects were 2 cohorts of students consisting of 619 enrolled in READ 180 during the school year of 2007-2008 and 358 students enrolled in READ 180 during the school year of 2010-2011 at an urban high school in New Jersey. Following a goals-based program evaluation design, a paired difference t test was used to evaluate classroom reading achievement; a chi-square test was used to evaluate graduation rates; and a multiple regression analysis controlling for initial status was used to evaluate performance on the standardized language arts test. Findings indicated moderate improvement in classroom reading achievement, no improvement in graduation rates, and strong improvement in standardized test scores only for English learners. Results suggested that a balanced literacy program such as READ 180 may provide effective reading remediation for English learners in low-income urban areas, thereby promoting social change through increased academic success and upward economic mobility.
358

The Red Top Model: A Landscape-Scale Integrodifference Equation Model of the Mountain Pine Beetle-Lodgepole Pine Forest Interaction

Heavilin, Justin 01 May 2007 (has links)
Under normative conditions the mountain pine beetle (Dendroctonus ponderosae Hopkins) has played a regulating role in healthy lodgepole pine (Pinus contorta) forests. However, recently eruptive outbreaks that result from large pine beetle populations have destroyed vast tracts of valuable forest. The outbreaks in North America have received a great deal of attention from both the timber industry and government agencies as well as biologists and ecologists. In this dissertation we develop a landscape-scaled integrodifference equation model describing the mountain pine beetle and its effect on a lodgepole pine forest. The model is built upon a stage-structured model of a healthy lodgepole pine forest with the addition of beetle pressure in the form of an infected tree class. These infected trees are produced by successful beetle attack, modelled by response functions. Different response functions reflect different probabilities for various densities. This feature of the model allows us to test hypotheses regarding density-dependent beetle attacks. To capture the spatial aspect of beetle dispersal from infected trees we employ dispersal kernels. These provide a probabilistic model for finding given beetle densities at some distance from infected trees. Just as varied response functions model different attack dynamics, the choice of kernel can model different dispersal behavior. The modular nature of the Red Top Model yields multiple model candidates. These models allow discrimination between broad possibilities at the land scape scale: whether or not beetles are subject to a threshold effect at the lands cape scale and whether or not host selection is random or directed. We fit the model using estimating functions to two distinct types of data: aerial damage survey data and remote sensing imagery. Having constructed multiple models, we introduce a novel model selection methodology for spatial models based on facial recognition technology. Because the regions and years of aerial damage survey and remote sensing data in the Sawtooth National Recreation Area overlap, we can compare the results from data sets to address the question of whether remote sensing data actually provides insight to the system that coarser scale but less expensive and more readily available aerial damage survey data does not.
359

Exploring selections across channels in Dark Matter searches with top quarks at the ATLAS experiment of the LHC

Sunneborn Gudnadottir, Olga January 2019 (has links)
Current estimates put Dark Matter to 26% of the energy-matter content of the universe, but very little is known about it other than its gravitational interactions. Eorts to learn more about Dark Matter include searching for it at high energy particle colliders. The lack of information about the nature of Dark Matter makes this a complicated task, and many searches are performed in dierent channels, and considering dierent theoretical models. In this thesis, I explore two such analyses, performed in the ATLAS collaboration using data from the ATLAS detector at the Large Hadron Collider at CERN: the tW+MET (missing transverse energy) nal state and the tt+MET nal state. I have made a generation-level study of the overlap between the signal regions used, and come to the conclusion that there is some. I have also compared the models used in these analyses, the 2HDM+a and the simplied spin-0 pseudoscalar model. Given the simplications made in my study, however, more sophisticated approaches should be used before anything conclusive can be said.
360

Board characteristics and firm performance: evidence from New Zealand

Bathula, Hanoku January 2008 (has links)
Due to various corporate scandals and failures, there has been a renewed interest on the role of boards in the performance of firms. This thesis examines the relationship between the key board characteristics and firm performance. Unlike most studies on boards which predominantly use only financial variables affecting governance, I take a different approach by combining them with non-financial variables. This combined set of variables is used for theoretical and empirical modelling. Based on the extant literature, I develop a conceptual framework and a set of hypotheses to examine the relationship between board characteristics and firm performance. Board characteristics considered in this research include board size, director ownership, CEO duality, gender diversity, educational qualification of board members and number of board meetings. Additionally, I use board size as a moderating variable to examine how the effect of other board characteristics is contingent on board size. Firm performance is measured by return on assets. I test my hypotheses on a longitudinal sample of 156 firms over a four year period from 2004 to 2007. My sample includes all firms listed on New Zealand stock exchange as on November 2007. Empirical analysis is undertaken using Generalised Least Squares analyses. The findings of the study show that board characteristics such as board size, CEO duality and gender diversity were positively related with firm performance, where as director ownership, board meetings and the number of board members with PhD level education was found to be negatively related. Board size was found to be moderating some of these relationships, indicating the critical role being played by board size in the design and role of corporate boards. The findings also provide partial evidence to different governance theories, further indicating the need for theoretical pluralism to gain insights into boards’ functioning. The study contributes to the understanding of board-performance link by examining both the traditional variables such as board size, CEO duality, and number of board meetings as well as other organisational attributes such as gender diversity and competence variables represented by women and PhD holders, respectively. The theoretical framework and the findings of my thesis are expected to stimulate scholars for further research to identify the contingency conditions upon which the board characteristics and firm performance may be dependent.

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