O objetivo desta dissertação foi desenvolver um método para implementação e acompanhamento de atividades a distância em disciplinas de Estatística, por meio de ambientes virtuais de aprendizagem. O método inclui alguns recursos comumente encontrados em ambientes virtuais, como materiais de leitura, fórum, chat, correio eletrônico, FAQ, links, espaço compartilhado de trabalho e quadro de notas. O método foi aplicado a uma disciplina semipresencial do curso de graduação em Administração da FEA-RP/USP. Este trabalho se configura como uma pesquisa qualitativa e descritiva, com delineamento por estudo de caso único, cuja coleta de dados ocorreu por meio de observação participante (nos processos de tutoria), entrevistas do tipo focus group, relatórios de acessos dos alunos ao ambiente e um survey sobre o perfil da turma. O gerenciamento do curso ocorreu conjuntamente com o processo de tutoria da disciplina, o que permitiu acompanhar os acessos dos alunos a cada recurso do ambiente e o seu desempenho nas atividades propostas. Observou-se que alguns recursos não foram utilizados da forma planejada pelo método. A análise de regressão revelou que, durante a primeira fase da disciplina, as discussões no fórum e o desempenho nos trabalhos práticos influenciaram positivamente o desempenho do aluno na prova. Na segunda fase, apenas o trabalho prático e o fórum influenciaram na nota da prova. A análise de cluster identificou quatro grupos de alunos com desempenho: excelente, bom, mediano e insatisfatório. Os resultados indicam que outras variáveis, além das atividades a distância, determinam o desempenho do aluno na disciplina. / The objective of this dissertation was to develop a method for distance activities introduction and attendance in Statistics subjects through learning virtual environments. The method includes some resources commonly found in virtual environments, such as reading materials, forum, chat, electronic mail, FAQ, links, shared work space, and table of notes. The method was applied to a subject semi-presence of the Administration graduation course of FEARP/ USP. This work is a qualitative and descriptive research, with an outline by a single casestudy, of which data collection occurred through present observation (in the tutorial processes), interviews like focus group, reports of students accesses to the environment and a survey about the group profile. The management of the course occurred together with the subject tutorial process, which allowed attending the students\' accesses to each environment resource and their development in the proposed activities. It was observed that some resources were not used in the planned way by the method. The regression analysis revealed that, during the first stage of the subject, the discussions in the forum and the development in the practical works influenced positively the student\'s development in the test. In the second stage just the practical work and the forum influenced in the test\'s grade. The cluster analysis identified four groups of students with excellent, good, medium, and unsatisfactory developments. The results indicate that other variables, besides the distance activities, determine the student\'s development in the subject.

[pt] A competição no setor de telefonia celular tem apresentado forte acirramento nos últimos anos, levando a uma tendência de queda no faturamento médio por usuário nas empresas. Os serviços de valor adicionado vêm cumprindo importante papel no esforço de aumento do faturamento das empresas com seus clientes. A mídia tem sido adotada por executivos do setor como instrumento de marketing para promover o uso de alguns serviços e, conseqüentemente, melhorar o faturamento médio por usuário. Neste contexto, o presente estudo tenta avaliar a relevância da mídia para o desempenho dos serviços de valor adicionado. Para tal, foram realizadas análises estatísticas no esforço de identificar a correlação entre volume de mídia e o tráfego de um determinado serviço de valor adicionado. Recorre-se a uma revisão bibliográfica de disciplinas de marketing de serviços, mídia e estatística aplicada. Também é conduzido um estudo de caso do serviço visando um melhor entendimento do contexto de negócios em que o mesmo está inserido, pois entende-se como fundamental para uma resposta mais consistente ao problema da pesquisa. Os resultados apontam para a relevância da mídia e também para outros aspectos importantes para o desempenho do serviço, tais como as características de uso do produto e o modelo comercial adotado entre os provedores do serviço e a empresa de mídia. / [en] The competition in the telephony sector has become harder in the last years, leading to a decrease in the average revenue per user of the companies. The value added services have been developing an important role in the effort of revenue increase by the companies with its users. Media has been adopted as a marketing tool by its executives to promote the usage of some services and, consequently, improve the average revenue per user. In this scenario, this study evaluates the media relevance to the performance of value added services. To conclude that, some statistical analysis were conducted in the effort to identify correlation between media volume and traffic of some value added services. A bibliographic revision was made in disciplines of marketing services, media and applied statistics. A case study was conducted aiming a better understanding of the service´s business context, as it is fundamental to a more consistent answer of the research problem. The results present the relevance of media and other aspects that are also important to the service performance, such as the products use characteristics and the business model adopted among the service providers and the media company.

The discovery of exoplanets represents one of the greatest scientific revolutions in history, and exoplanetary science has rapidly become uniquely positioned to address profound questions about the origins of life, and about humanity's place (and future) in the cosmos. Since the discovery of the first exoplanet over two decades ago, the radial velocity (RV) method has been one of the most productive techniques for discovering new planets. It has also become indispensable for characterising exoplanets detected via other techniques, notably transit photometry. Unfortunately, signals intrinsic to stars themselves - especially magnetic activity signals - can induce RV variations that can drown out or even mimic planetary signals. Modelling and thus mitigating these signals is notoriously difficult, which represents a major obstacle to using next-generation instruments to detect lower mass planets, planets with longer periods, and planets around more magnetically-active stars. Enter Gaussian processes (GPs), which have a number of features that make them very well suited to the joint modelling of stochastic activity processes and dynamical (e.g. planetary) signals. In this thesis, I leverage GPs to enable the study of smaller planets around a wider variety of stars than has previously been possible. In particular, I develop a principled and sophisticated Bayesian framework, based on GPs, for modelling RV time series jointly with ancillary activity-sensitive proxies, thus allowing activity signals to be constrained and disentangled from genuine planetary signals. I show that my framework succeeds even in cases where existing techniques would fail to detect planets, e.g. the case of a weak planetary signal with period identical to its host star's rotation period. In a first application of the framework, I demonstrate that Alpha Centauri Bb - until 2016, thought to be the closest exoplanet to Earth, and also the lowest minimum-mass exoplanet around a Sun-like star - was, in fact, an astrophysical false positive. Next, I use the framework to re-characterise the well-studied Kepler-10 system, thereby resolving a mystery surrounding the mass of planet Kepler-10c. I also use the framework to help discover or characterise various exoplanets. Finally, the activity modelling framework aside, I also present in outline form a few promising applications of GPs in the context of modelling stellar signals and studying exoplanets, viz. GPs for (i) enhanced characterisation of stellar rotation; (ii) generating realistic synthetic observations, and modelling in a systematic way the effects of an observing window function; and (iii) ultra-precise extraction of RV shifts directly from observed spectra, without requiring template cross-correlation.

O objetivo desta dissertação foi desenvolver um método para implementação e acompanhamento de atividades a distância em disciplinas de Estatística, por meio de ambientes virtuais de aprendizagem. O método inclui alguns recursos comumente encontrados em ambientes virtuais, como materiais de leitura, fórum, chat, correio eletrônico, FAQ, links, espaço compartilhado de trabalho e quadro de notas. O método foi aplicado a uma disciplina semipresencial do curso de graduação em Administração da FEA-RP/USP. Este trabalho se configura como uma pesquisa qualitativa e descritiva, com delineamento por estudo de caso único, cuja coleta de dados ocorreu por meio de observação participante (nos processos de tutoria), entrevistas do tipo focus group, relatórios de acessos dos alunos ao ambiente e um survey sobre o perfil da turma. O gerenciamento do curso ocorreu conjuntamente com o processo de tutoria da disciplina, o que permitiu acompanhar os acessos dos alunos a cada recurso do ambiente e o seu desempenho nas atividades propostas. Observou-se que alguns recursos não foram utilizados da forma planejada pelo método. A análise de regressão revelou que, durante a primeira fase da disciplina, as discussões no fórum e o desempenho nos trabalhos práticos influenciaram positivamente o desempenho do aluno na prova. Na segunda fase, apenas o trabalho prático e o fórum influenciaram na nota da prova. A análise de cluster identificou quatro grupos de alunos com desempenho: excelente, bom, mediano e insatisfatório. Os resultados indicam que outras variáveis, além das atividades a distância, determinam o desempenho do aluno na disciplina. / The objective of this dissertation was to develop a method for distance activities introduction and attendance in Statistics subjects through learning virtual environments. The method includes some resources commonly found in virtual environments, such as reading materials, forum, chat, electronic mail, FAQ, links, shared work space, and table of notes. The method was applied to a subject semi-presence of the Administration graduation course of FEARP/ USP. This work is a qualitative and descriptive research, with an outline by a single casestudy, of which data collection occurred through present observation (in the tutorial processes), interviews like focus group, reports of students accesses to the environment and a survey about the group profile. The management of the course occurred together with the subject tutorial process, which allowed attending the students\' accesses to each environment resource and their development in the proposed activities. It was observed that some resources were not used in the planned way by the method. The regression analysis revealed that, during the first stage of the subject, the discussions in the forum and the development in the practical works influenced positively the student\'s development in the test. In the second stage just the practical work and the forum influenced in the test\'s grade. The cluster analysis identified four groups of students with excellent, good, medium, and unsatisfactory developments. The results indicate that other variables, besides the distance activities, determine the student\'s development in the subject.