An EM-based Semi-Parametric Mixture Model Approach to the Regression Analysis of Competing-Risks Data

We consider a mixture model approach to the regression analysis of competing-risks data. Attention is focused on inference concerning the effects of factors on both the probability of occurrence and the hazard rate conditional on each of the failure types. These two quantities are specified in the mixture model using the logistic model and the proportional hazards model, respectively. We propose a semi-parametric mixture method to estimate the logistic and regression coefficients jointly, whereby the component-baseline hazard functions are completely unspecified. Estimation is based on maximum likelihood on the basis of the full likelihood, implemented via an expectation-conditional maximization (ECM) algorithm. Simulation studies are performed to compare the performance of the proposed semi-parametric method with a fully parametric mixture approach. The results show that when the component-baseline hazard is monotonic increasing, the semi-parametric and fully parametric mixture approaches are comparable for mildly and moderately censored samples. When the component-baseline hazard is not monotonic increasing, the semi-parametric method consistently provides less biased estimates than a fully parametric approach and is comparable in efficiency in the estimation of the parameters for all levels of censoring. The methods are illustrated using a real data set of prostate cancer patients treated with different dosages of the drug diethylstilbestrol. Copyright (C) 2003 John Wiley Sons, Ltd.

Effect of changing data collection parameters on statistical motor unit number estimates

The effect of number of samples and selection of data for analysis on the calculation of surface motor unit potential (SMUP) size in the statistical method of motor unit number estimates (MUNE) was determined in 10 normal subjects and 10 with amyotrophic lateral sclerosis (ALS). We recorded 500 sequential compound muscle action potentials (CMAPs) at three different stable stimulus intensities (10–50% of maximal CMAP). Estimated mean SMUP sizes were calculated using Poisson statistical assumptions from the variance of 500 sequential CMAP obtained at each stimulus intensity. The results with the 500 data points were compared with smaller subsets from the same data set. The results using a range of 50–80% of the 500 data points were compared with the full 500. The effect of restricting analysis to data between 5–20% of the CMAP and to standard deviation limits was also assessed. No differences in mean SMUP size were found with stimulus intensity or use of different ranges of data. Consistency was improved with a greater sample number. Data within 5% of CMAP size gave both increased consistency and reduced mean SMUP size in many subjects, but excluded valid responses present at that stimulus intensity. These changes were more prominent in ALS patients in whom the presence of isolated SMUP responses was a striking difference from normal subjects. Noise, spurious data, and large SMUP limited the Poisson assumptions. When these factors are considered, consistent statistical MUNE can be calculated from a continuous sequence of data points. A 2 to 2.5 SD or 10% window are reasonable methods of limiting data for analysis. Muscle Nerve 27: 320–331, 2003

Model-based clustering in gene expression microarrays: An application to breast cancer data

In microarray studies, the application of clustering techniques is often used to derive meaningful insights into the data. In the past, hierarchical methods have been the primary clustering tool employed to perform this task. The hierarchical algorithms have been mainly applied heuristically to these cluster analysis problems. Further, a major limitation of these methods is their inability to determine the number of clusters. Thus there is a need for a model-based approach to these. clustering problems. To this end, McLachlan et al. [7] developed a mixture model-based algorithm (EMMIX-GENE) for the clustering of tissue samples. To further investigate the EMMIX-GENE procedure as a model-based -approach, we present a case study involving the application of EMMIX-GENE to the breast cancer data as studied recently in van 't Veer et al. [10]. Our analysis considers the problem of clustering the tissue samples on the basis of the genes which is a non-standard problem because the number of genes greatly exceed the number of tissue samples. We demonstrate how EMMIX-GENE can be useful in reducing the initial set of genes down to a more computationally manageable size. The results from this analysis also emphasise the difficulty associated with the task of separating two tissue groups on the basis of a particular subset of genes. These results also shed light on why supervised methods have such a high misallocation error rate for the breast cancer data.

Zygosity Diagnosis in the Absence of Genotypic Data: An Approach Using Latent Class Analysis

For zygosity diagnosis in the absence of genotypic data, or in the recruitment phase of a twin study where only single twins from same-sex pairs are being screened, or to provide a test for sample duplication leading to the false identification of a dizygotic pair as monozygotic, the appropriate analysis of respondents' answers to questions about zygosity is critical. Using data from a young adult Australian twin cohort (N = 2094 complete pairs and 519 singleton twins from same-sex pairs with complete responses to all zygosity items), we show that application of latent class analysis (LCA), fitting a 2-class model, yields results that show good concordance with traditional methods of zygosity diagnosis, but with certain important advantages. These include the ability, in many cases, to assign zygosity with specified probability on the basis of responses of a single informant (advantageous when one zygosity type is being oversampled); and the ability to quantify the probability of misassignment of zygosity, allowing prioritization of cases for genotyping as well as identification of cases of probable laboratory error. Out of 242 twins (from 121 like-sex pairs) where genotypic data were available for zygosity confirmation, only a single case was identified of incorrect zygosity assignment by the latent class algorithm. Zygosity assignment for that single case was identified by the LCA as uncertain (probability of being a monozygotic twin only 76%), and the co-twin's responses clearly identified the pair as dizygotic (probability of being dizygotic 100%). In the absence of genotypic data, or as a safeguard against sample duplication, application of LCA for zygosity assignment or confirmation is strongly recommended.

Systematic characterization of mutations in yeast acetohydroxyacid synthase: Interpretation of herbicide-resistance data

Acetohydroxyacid synthase (AHAS, EC 4.1.3.18) catalyses the first step in branched-chain amino acid biosynthesis and is the target for sulfonylurea and imidazolinone herbicides, which act as potent and specific inhibitors. Mutants of the enzyme have been identified that are resistant to particular herbicides. However, the selectivity of these mutants towards various sulfonylureas and imidazolinones has not been determined systematically. Now that the structure of the yeast enzyme is known, both in the absence and presence of a bound herbicide, a detailed understanding of the molecular interactions between the enzyme and its inhibitors becomes possible. Here we construct 10 active mutants of yeast AHAS, purify the enzymes and determine their sensitivity to six sulfonylureas and three imidazolinones. An additional three active mutants were constructed with a view to increasing imidazolinone sensitivity. These three variants were purified and tested for their sensitivity to the imidazolinones only. Substantial differences are observed in the sensitivity of the 13 mutants to the various inhibitors and these differences are interpreted in terms of the structure of the herbicide-binding site on the enzyme.

Data Mart para apoio ?? capacita????o em gest??o de pol??ticas p??blicas voltado para uma Escola de Administra????o P??blica

Este trabalho consiste num estudo de caso que se destina ao desenvolvimento de um Data Mart que possibilite a Escola Nacional de Administra????o P??blica ??? ENAP conhecer o perfil e o panorama geral da situa????o funcional dos servidores p??blicos federais que se capacitaram na Escola nos ??ltimos 7 anos. O aplicativo foi desenvolvido cruzando o banco de dados do sistema gerenciador dos cursos ministrados pela ENAP, onde est??o armazenadas informa????es sobre os alunos capacitados, os cursos realizados, os resultados alcan??ados, o perfil dos docentes e demais informa????es relativas ??s atividades da Escola, com os dados gerados pelo Sistema Integrado de Administra????o de Recursos Humanos ??? SIAPE, cuja extra????o de dados foi direcionada para os registros sobre a situa????o funcional, cargos, carreiras, fun????es, ??rg??os e alguns dados pessoais dos alunos, servidores p??blicos federais que se encontram registrados no SIAPE

New species of Bakeriella (Hymenoptera, Bethylidae) from the New World and new data on geographic distribution

Bakeriella lata sp. nov. (Brazil, Rondônia), Bakeriella aurata sp. nov. (Brazil, Amazonas) and Bakeriella sulcaticeps sp. nov. (Brazil, Amazonas) are described and illustrated. New geographic records and variation data for B. cristata Evans, 1964, B. floridana Evans, 1964, B. flavicornis Kieffer, 1910, B. incompleta Azevedo, 1994, B. mira Evans, 1997, B. montivaga (Kieffer, 1910), B. olmeca Evans, 1964 and B. subcarinata Evans, 1965 are provided. The male of B. incompleta is described for the first time.

Avaliação da qualidade dos serviços prestados pela Biblioteca Central da UFES utilizando o método Servqual

O presente trabalho objetiva avaliar a qualidade dos serviços prestados pela Biblioteca Central (BC) da Universidade Federal do Espírito Santo (UFES) utilizando o método Servqual. Esta pesquisa é um estudo de caso de natureza quantitativa e qualitativa. A triangulação dos dados foi realizada por meio de uma survey com 363 usuários, entrevista com nove servidores que atuam na Biblioteca e consulta a documentos da universidade que descrevem as características básicas da Biblioteca Central. A survey foi aplicada utilizando-se questionário desenvolvido com base na escala Servqual em pré-teste realizado na Biblioteca Setorial Tecnológica (BST) da UFES. Foram utilizadas duas modalidades de coleta na survey aplicada na BC: presencial e online. Foram coletados 110 questionários presenciais e 253 online. As entrevistas com os servidores da BC foram baseadas nos 116 registros de reivindicações dos usuários, coletados pela BC anteriormente à pesquisa. Além desses documentos, consultaramse informações institucionais divulgadas no catálogo de serviços da BC e em páginas da BC e da UFES na internet. Identificaram-se quatro dimensões da qualidade dos serviços prestados pela BC, com médias negativas, indicando necessidade de melhoria nos serviços prestados. As ações prioritárias recomendadas para a BC são: a) melhorar instalações físicas e equipamentos; e b) capacitar e motivar os trabalhadores para atendimento aos usuários. Essas ações devem conduzir a soluções de problemas relacionados a condições de estudo (iluminação, climatização, água, banheiros, espaço físico, móveis e silêncio) e acesso a informação (internet, autoempréstimo, quantitativo de exemplares, limitação do empréstimo e alerta quanto à data de renovação).

Eu bebo sim e estou vivendo : qualidade de vida, masculinidade, padrões de consumo de álcool e representações sociais de bebida alcoólica para homens usuários de unidade de saúde da família

A Política Nacional de Atenção Integral à Saúde do Homem propõe formas diferenciadas de atuação da equipe de saúde no atendimento da população masculina, uma vez que este público demanda estratégias diferenciadas de serviço. Ao se deparar com a realidade vivenciada pelos homens, surgem várias questões acerca do estereótipo social construído acerca das características masculinas e suas vivências. O objetivo da pesquisa foi compreender alguns aspectos relevantes para as práticas de saúde de homens usuários de Unidade de Saúde da Família, como qualidade de vida, consumo de álcool, representações sociais da bebida alcoólica e características de masculinidade. Foi utilizada uma amostra de 300 homens, frequentadores de Unidade de Saúde da Família, e aplicado um questionário contendo os dados sociodemográficos, o World Health Organization Quality of Life (Whoqol-bref), o Bem Sex-Role Inventory (BSRI), um exercício de evocação sobre bebida alcoólica, o Alcohol Use Disorders Identification Test (Audit) e um bloco para verificar os problemas ocasionados pelo consumo de álcool e a procura por tratamento. Os dados dos instrumentos quantitativos foram analisados com testes estatísticos de comparação de médias e de correlação. Os dados das evocações foram analisados com o software EVOC (Ensemble de Programmes Permettant l’Analyse des Évocations). Na primeira análise, constatou-se adesão mais alta a características femininas, alta percepção de qualidade de vida e padrões de consumo de álcool semelhantes às médias nacionais. Homens que declararam praticar sua religião apresentaram média significativamente menor de consumo de álcool. Apresentaram correlação inversamente proporcional ao consumo de álcool as características femininas de gênero, os domínios físico, social, psicológico e percepção global de qualidade de vida. Na análise das evocações, constatou-se que os elementos com tendência à centralidade são, em sua maioria, de cunho negativo. Os dados da população geral apresentaram o termo gosto como um aspecto positivo e central da bebida alcoólica. O grupo de abstinentes não apresentou avaliação positiva do termo e o grupo de bebedores apresentou o termo diversão na primeira periferia, referindo-se aos aspectos positivos e de socialização da bebida alcoólica. Os resultados indicaram uma qualidade de vida satisfatória, a religião e as características femininas destacaram-se como um fator de proteção ao uso de bebida alcoólica. Apresentaram, ainda, percepção dos problemas associados ao próprio consumo. Apesar de a maioria dos termos relacionados à bebida alcoólica ser negativo, este consumo ainda se dá em um nível considerável. Por isso, se faz necessária a construção de vínculo entre o profissional e o usuário do serviço de saúde a fim de dar oportunidade para que as reais práticas sobre a bebida alcoólica sejam evidenciadas. Esses dados podem ajudar profissionais de Saúde da Família a refletirem sobre as representações sociais que constroem acerca dos homens de classe popular usuários do serviço

Sensor-driven agenda for intelligent home care of the elderly

The exponential increase of home-bound persons who live alone and are in need of continuous monitoring requires new solutions to current problems. Most of these cases present illnesses such as motor or psychological disabilities that deprive of a normal living. Common events such as forgetfulness or falls are quite common and have to be prevented or dealt with. This paper introduces a platform to guide and assist these persons (mostly elderly people) by providing multisensory monitoring and intelligent assistance. The platform operates at three levels. The lower level, denominated ‘‘Data acquisition and processing’’performs the usual tasks of a monitoring system, collecting and processing data from the sensors for the purpose of detecting and tracking humans. The aim is to identify their activities in an intermediate level called ‘‘activity detection’’. The upper level, ‘‘Scheduling and decision-making’’, consists of a scheduler which provides warnings, schedules events in an intelligent manner and serves as an interface to the rest of the platform. The idea is to use mobile and static sensors performing constant monitoring of the user and his/her environment, providing a safe environment and an immediate response to severe problems. A case study on elderly fall detection in a nursery home bedroom demonstrates the usefulness of the proposal.

A Platform to Emulate Ambient Assisted Living Environments

According to the opinion of clinicians, emerging medical conditions can be timely detected by observing changes in the activities of daily living and/or in the physiological signals of a person. To accomplish such purpose, it is necessary to properly monitor both the person’s physiological signals as well as the home environment with sensing technology. Wireless sensor networks (WSNs) are a promising technology for this support. After receiving the data from the sensor nodes, a computer processes the data and extracts information to detect any abnormality. The computer runs algorithms that should have been previously developed and tested in real homes or in living-labs. However, these installations (and volunteers) may not be easily available. In order to get around that difficulty, this paper suggests the making of a physical model to emulate basic actions of a user at home, thus giving autonomy to researchers wanting to test the performance of their algorithms. This paper also studies some data communication issues in mobile WSNs namely how the orientation of the sensor nodes in the body affects the received signal strength, as well as retransmission aspects of a TDMA-based MAC protocol in the data recovery process.

The need for standardized tests to evaluate the reliability of data transport in wireless medical systems

Wireless medical systems are comprised of four stages, namely the medical device, the data transport, the data collection and the data evaluation stages. Whereas the performance of the first stage is highly regulated, the others are not. This paper concentrates on the data transport stage and argues that it is necessary to establish standardized tests to be used by medical device manufacturers to provide comparable results concerning the communication performance of the wireless networks used to transport medical data. Besides, it suggests test parameters and procedures to be used to produce comparable communication performance results.

A brief survey on online analysis of movement data

The increasing availability of mobility data and the awareness of its importance and value have been motivating many researchers to the development of models and tools for analyzing movement data. This paper presents a brief survey of significant research works about modeling, processing and visualization of data about moving objects. We identified some key research fields that will provide better features for online analysis of movement data. As result of the literature review, we suggest a generic multi-layer architecture for the development of an online analysis processing software tool, which will be used for the definition of the future work of our team.

GUIsurfer: A Reverse Engineering Framework for User Interface Software

GUIsurfer: A Reverse Engineering Framework for User Interface Software