Group testing has long been considered as a safe and sensible relative to one-at-a-time testing in applications where the prevalence rate p is small. In this thesis, we applied Bayes approach to estimate p using Beta-type prior distribution. First, we showed two Bayes estimators of p from prior on p derived from two different loss functions. Second, we presented two more Bayes estimators of p from prior on π according to two loss functions. We also displayed credible and HPD interval for p. In addition, we did intensive numerical studies. All results showed that the Bayes estimator was preferred over the usual maximum likelihood estimator (MLE) for small p. We also presented the optimal β for different p, m, and k.

What is the probability that in a fair coin toss game (a simple random walk) we go bankrupt in n steps when there is an initial lead of some known or unknown quantity $m? What is the distribution of the number of steps N that it takes for the lead to vanish? This thesis explores some of the features of this first passage to the origin (FPO) distribution. First, we explore the distribution of N when m is known. Next, we compute the maximum likelihood estimators of m for a fixed n and also the posterior distribution of m when we are given that m follows some known prior distribution.

The work aimed at identifying indicators for the adaptation of the virtual learning environment Mobile Learning Engine Moodle (MLE Moodle) to the cognitive styles of students through a system created to diagnose learning styles (SEDECA), developed to support the proposed adjustment. The research presented had as an objective to gather data about the main categories, predominating cognitive styles of the participants and their actions on the virtual learning environment MLE Moodle. The analysis of these categories allowed the definition of indicators, which made possible the adaptation of the virtual learning environment MLE Moodle to the different cognitive styles utilizing the adaptive hypermedia. The validation of the system was done in two groups where a course on educational softwares was taught. The materials and activities proposed on the adapted environment were presented according to the four most present cognitive styles in the research: Holist, Serialist, Divergent and Reflexive. Results show that the AVA MLE MOODLE with environment and content adapted to the different cognitive styles has influenced positively on the students learning process and also on their cognitive structure. This work stands out because it implements SEDECA integrated to the mobile virtual learning environment MLE Moodle accessed on a mobile device as well as on a desktop. / O trabalho desenvolvido objetivou identificar indicadores para a adaptação do Ambiente Virtual de Aprendizagem Mobile Learning Engine Moodle (MLE Moodle) ao estilo cognitivo do aluno por meio do Sistema criado para diagnosticar estilos de aprendizagem (SEDECA), desenvolvido para dar suporte à adaptação proposta. A pesquisa apresentada teve por objetivo realizar um levantamento de dados sobre principais categorias, estilos cognitivos predominantes dos participantes e ação dos mesmos no ambiente virtual de aprendizagem MLE Moodle. A análise dessas categorias permitiu definir indicadores, que possibilitaram a adaptação do ambiente virtual de aprendizagem MLE Moodle a esses diferentes estilos cognitivos utilizando a hipermídia adaptativa. A validação do sistema foi realizada em duas turmas, onde foi ministrado um Curso sobre Softwares Educativos. Os materiais e atividades propostas no ambiente adaptado foram apresentados de acordo com os quatro Estilos cognitivos que mais se destacaram na pesquisa: Holista, Serialista, Divergente e Reflexivo. Os resultados inferidos mostram que o AVA Mle Moodle adaptado (adaptação do ambiente e conteúdo) aos diferentes estilos cognitivos influenciou positivamente no processo de aprendizagem dos alunos e consequentemente na sua estrutura cognitiva. Este trabalho diferencia-se por implementar o SEDECA integrado ao ambiente virtual de aprendizagem móvel MLE Moodle acessado via dispositivo móvel, como também, ao ambiente Moodle acessado via desktop.

It is widely recognised that parents play an important role in children’s emotional and intellectual development, including their success at school. Recently, there has been a growing awareness of the potential of parents to support and enhance children’s English foreign language learning, especially since English learning resources are easily accessible through electronic media. In appreciation of this, there has been an increased interest in recent years in finding ways to harness parental potential through the creation of home-school partnerships in many parts of the world, including in the field of teaching English as an additional language. An important point of departure for developing effective home-school dialogues is an informed understanding of what parents are already doing to support their children’s learning, as an awareness of this can help schools and governments provide parents with targeted input to assist and improve their efforts. However, to date, this remains under researched. Of the limited research that has been undertaken, very little has examined parental efforts to support their children’s learning at home in non-western settings, and research into parental support for children’s foreign language learning is virtually non-existent. In order to address this research gap, the study reported in this thesis examines parental support for young children’s foreign language learning in Saudi Arabia with respect to English T.V. viewing. Drawing upon Vygotsky’s concepts of mediation and the ZPD, it aims to examine the extent and the ways in which parents currently mediate their children’s viewing of English T.V. programmes in Saudi Arabia, the factors which impact on their mediation practices, and how this is seen to contribute to their children’s experience of English language learning. The study is comprised two stages. The first stage entails the distribution of a questionnaire to 500 parents of children aged 6-8, who are currently learning English in a number of private schools in Jeddah, in Saudi Arabia in order to gain a global overview of parental perspectives on mediation. This is followed by stage 2, which aims to examine the features and quality of parent-child mediational dialogues. This is achieved by collecting recordings of the dialogues of two parent-child dyads watching DVDs of English T.V. programmes over a four-week period as well as interviewing parents and their children on the experience. The results of the study show that parents believe in the importance and value of supporting their children’s learning (both in general and with regard to their EFL learning). Moreover, they show that they are actively engaged in trying to do so. However, they also highlight a number of ways in which their mediational practices could be improved so that these are less directive and more responsive to their children’s learning needs and growing ability to self-regulate. More broadly, they highlight the need to engage with the complexity of parental mediation as an activity system in discussions of the quality of mediational practice. That is, to understand that parental efforts to mediate need to be considered alongside task, sociocultural setting and, most importantly, the child’s engagement with parental efforts. A number of implications are drawn from the results of the study. Chief among these is that research into parental mediation should look at the inter-relationship between the different elements of the parental mediational system identified and that this provides richer in-depth understandings of parental efforts to support their children than are currently available from those who seek to understand this merely as parental scaffolding. In addition, it is argued that the picture this in-depth analysis revealed provides valuable information which can be used to inform the need for home-school partnerships and the support parents need to make sure they engage in these effectively in settings such as Saudi Arabia where there is currently little appreciation of the importance of parental involvement and the concept of home school partnerships remains in its infancy. In line with the emphasis on the complex multidimensional understanding of mediation as activity as illustrated by the results of the study, it is argued that efforts to promote parental involvement should primarily focus on how parents can help promote quality learning experiences for their children.

The outcome of a production process might not only deviate from a theoretical maximum due to inefficiency, but also because of non-controllable influences. This raises the issue of reliability of Data Envelopment Analysis in noisy environments. I propose to assume an i.i.d. data generating process with bounded noise component, so that the following approach is feasible: Use DEA to estimate a pseudo frontier first (nonparametric shape estimation). Next apply a ML-technique to the DEA-estimated efficiencies, to estimate the scalar value by which this pseudo-frontier must be shifted downward to get the true production frontier (location estimation). I prove, that this approach yields consistent estimates of the true frontier. (author's abstract) / Series: Department of Economics Working Paper Series

<p>In Drosophila melanogaster, where males are XY and females are XX, dosage compensation is acheived by approximately two-fold upregulation of transcription of the single male X chromosome. This upregulation is mediated by the dosage compensation complex (DCC), which is assembled in a sequential manner on the male X chromosome and is composed of the two noncoding roX (RNA on the X) RNAs and at least five proteins, including the RNA helicase Maleless (MLE). MLE contains two highly conserved double stranded RNA binding domains (DRBDs) at the N terminus. We investigated the roles of the roX RNAs and MLE helicase through experiments using classical genetic methods to generate and analyze the effects of mutants and mutant transgenes, immunolocalization experiments to study MSL protein and roX RNA to chromosomes. For the first time in vivo, we demonstrate that MLE associates with double stranded RNA in a sequence non-specific manner that is independent of other DCC components. Importantly, we find that the DSRBDs of MLE are essential for dosage compensation but are not required for MLE localization to the male X chromosome. We propose that although the DSRBDs are not essential for ds RNA binding, they may act synergistically with other domains of MLE or other MSLs to associate with RNA in vivo. We propose that a MLE/ roX RNA association involving secondary structure formed by the roX RNAs may be involved in the assembly, stabilization, or function of the DCC.</p> / Dissertation

Most recorded data are rounded to the nearest decimal place due to the precision of the recording mechanism. This rounding entails errors in estimation and measurement. In this paper, we compare the performances of three types of estimators based on rounded data from time series models, namely A-K corrected estimator, approximate MLE and the SOS estimator. In order to perform the comparison, the A-K corrected estimators for the MA(1) model are derived theoretically. To improve the efficiency of the estimation, two types of variance-reduction estimators are further proposed, which are based on linear combinations of aforementioned three estimators. Simulation results show the proposed variance reduction estimators significantly improve the estimation efficiency.

Surgeon operation time is a useful and important information for hospital management, which involves operation time estimation for patients under different diagnoses, operation room scheduling, operating room utilization improvements and so on. In this work, we will focus on studying the operation time distributions of thirteen operations performed in the gynecology (GYN) department of one major teaching hospital in southern Taiwan. We firstly investigate what types of distributions are suitable in describing these operation times empirically, where log-normal and mixture log-normal distribution are identified to be acceptable statistically in describing these operation times. Then we compare and characterize the operations into different categories based on the operation time distribution estimates. Later we try to illustrate the possible reason why distributions for some operations with large data set turn out to be mixture of certain log-normal distributions. Finally we end with discussions on possible future work.

This thesis presents how to estimate the length of a power cable using the MaximumLikelihood Estimate (MLE) technique by using Matlab. The model of the power cableis evaluated in the time domain with additive white Gaussian noise. The statistics havebeen used to evaluate the performance of the estimator, by repeating the experiment fora large number of samples where the random additive noise is generated for each sample.The estimated sample variance is compared to the theoretical Cramer Raw lower Bound(CRLB) for unbiased estimators. At the end of thesis, numerical results are presentedthat show when the resulting sample variance is close to the CRLB, and hence that theperformance of the estimator will be more accurate.

Binomial group testing has been long recognized as an efficient method of estimating proportion of subjects with a specific characteristic. The method is superior to the classic maximum likelihood estimator (MLE), particularly when the proportion is small. Under the group testing model, we assume the testing is conducted without error. In the present research, a new Bayes estimator will be proposed that utilizes an additional piece of information, the proportion to be estimated is small and within a given range. It is observed that with the appropriate choice of the hyper-parameter our new Bayes estimator has smaller mean squared error (MSE) than the classic MLE, Burrows estimator, and the existing Bayes estimator. Furthermore, on the basis of heavy Monte Carlo simulation we have determined the best hyper-parameters in the sense that the corresponding new Bayes estimator has the smallest MSE. A table of these best hyper-parameters is made for proportions within the considered range.