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Neural networks and statistical analysis for classification of corneal videokeratography maps based on Zernike coefficients: a quantitative comparison; Redes neurais e análise estatística para classificação de mapas topográficos da córnea baseados em coeficientes de Zernike: uma comparação quantitativa

CARVALHO, Luis Alberto Vieira de; BARBOSA, Marconi Soares
Fonte: Conselho Brasileiro de Oftalmologia Publicador: Conselho Brasileiro de Oftalmologia
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
55.8%
PURPOSE: The main goal of this study was to develop and compare two different techniques for classification of specific types of corneal shapes when Zernike coefficients are used as inputs. A feed-forward artificial Neural Network (NN) and discriminant analysis (DA) techniques were used. METHODS: The inputs both for the NN and DA were the first 15 standard Zernike coefficients for 80 previously classified corneal elevation data files from an Eyesys System 2000 Videokeratograph (VK), installed at the Departamento de Oftalmologia of the Escola Paulista de Medicina, São Paulo. The NN had 5 output neurons which were associated with 5 typical corneal shapes: keratoconus, with-the-rule astigmatism, against-the-rule astigmatism, "regular" or "normal" shape and post-PRK. RESULTS: The NN and DA responses were statistically analyzed in terms of precision ([true positive+true negative]/total number of cases). Mean overall results for all cases for the NN and DA techniques were, respectively, 94% and 84.8%. CONCLUSION: Although we used a relatively small database, results obtained in the present study indicate that Zernike polynomials as descriptors of corneal shape may be a reliable parameter as input data for diagnostic automation of VK maps...

Sobre o emprego e a análise estatística do delineamento em blocos aumentados no melhoramento genético vegetal.; Application and statistical analysis of augmented block design in plant breeding.

Duarte, João Batista
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/05/2000 Português
Relevância na Pesquisa
65.96%
A presente pesquisa propôs-se a investigar problemas de ordem estatístico-experimental relacionados à aplicação do delineamento de blocos aumentados, em programas de melhoramento genético vegetal. Nesses desenhos experimentais há duas categorias de tratamentos: as testemunhas (repetidas) e os tratamentos adicionais ou novos (normalmente não repetidos). As primeiras usualmente são cultivares comerciais já recomendados, e os outros, os novos materiais genéticos sob avaliação. Sua relação com os delineamentos de blocos em geral, princípios para a sua aplicação e análise estatística, bem como informações correlatas de outros temas aqui investigados (modelos mistos, componentes de variância e análise espacial de experimentos) foram objetos de revisão no Capítulo 1. O material que fundamentou este trabalho foi um conjunto de 41 ensaios de competição de linhagens de soja (genótipos), em gerações de autofecundação nunca inferiores a F5. Os ensaios, assim delineados, fazem parte do Programa de Melhoramento da Soja desenvolvido pelo Setor de Genética Aplicada às Espécies Autógamas, do Departamento de Genética da ESALQ/USP. Foram escolhidos, preferencialmente, os ensaios que dispunham de mapa de campo completo...

A utilização do processo de avaliação on-line como apoio ao ensino presencial: desenvolvimento e análise junto ao laboratório virtual de estatística aplicada à administração - LaViE; Online evaluation process used as support to presencial teaching : development and analysis at the virtual laboratory of statistics applied to business management - LaViE

Marques, Érica Ferreira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/04/2007 Português
Relevância na Pesquisa
55.87%
As dificuldades de aprendizagem sobre estatística e suas aplicações simplesmente em razão da matemática envolvida, principalmente, pelos alunos dos cursos de humanas, fazem dela um desafio para o professor que a ministra e também para o aluno que aprende. Assim, esta tese busca mostrar o quanto à elaboração e o desenvolvimento de uma ferramenta de avaliação tipo teste em um ambiente virtual pode contribuir como apoio ao ensino presencial do estudo de ferramentas estatísticas multivariadas para os alunos de graduação em Administração da FEARP/USP, matriculados na disciplina Estatística Aplicada à Administração II. Este trabalho faz parte do projeto virtual denominado LaViE, que é um ambiente virtual de ensino-aprendizagem de estatística, e que está fundamentado em três dimensões: Pedagogia Virtual, Tecnologia da Comunicação e Processo de Validação. Para a criação dessa ferramenta de avaliação tipo teste online foi necessário, primeiramente, a elaboração de um protocolo para desenvolvimento e implementação desse sistema no LaViE. A metodologia, então, foi baseada em três etapas: 1) elaboração do protocolo fundamentado na pesquisa exploratória de pedagogia virtual com base na teoria sobre processo de ensino-aprendizagem para o desenvolvimento de um conjunto de regras e passos que balizasse a criação de questões testes on-line com níveis diferentes de ?adaptação? pelo aluno para cada módulo apresentado na disciplina em questão. Neste caso...

Caracterização de tecidos mamários através de modelos estatísticos utilizando o espalhamento de raios-x".; Breast Tissue Characterization by Statistical Models Using X-Ray Scattering

Cunha, Diego Merigue da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: dissertação de mestrado Formato: application/pdf
Publicado em 24/03/2006 Português
Relevância na Pesquisa
55.95%
Em um exame mamográfico, quando os fótons de raios-X incidem sobre a mama, uma parte destes fótons é transmitida sem ser desviada da trajetória inicial (radiação transmitida primária), permitindo a formação da imagem mamográfica, e outra é dispersa de sua trajetória inicial pelo tecido (radiação espalhada), atuando de forma deletéria na imagem mamográfica. Entretanto, recentes investigações têm demonstrado que a radiação espalhada pode ser útil na caracterização de tecidos. O objetivo deste trabalho é desenvolver um modelo de diagnóstico de alterações no tecido mamário utilizando as informações presentes na distribuição angular da radiação espalhada (perfil de espalhamento). Os perfis de espalhamento de 40 amostras de tecidos mamários foram obtidos utilizando um difractômetro comercial SIEMENS D5005, operando em modo reflexão na energia de 8,04 keV e variando o detector da posição angular de 5º a 150º, correspondendo a um intervalo de x de 0,03Å-1 a 0,62 Å-1. As amostras de tecido foram previamente classificadas histopatologicamente como tecidos normais, fibroadenomas (neoplasias benignas) e diferentes tipos de carcinomas (neoplasias malignas). Neste trabalho, três modelos de diagnóstico baseados na análise estatística dos perfis de espalhamento foram desenvolvidos. O primeiro...

Otimização das colunas de absorção da recuperação de acetona na produção de Filter Tow por meio de estudos fenomenológicos e análise estatística.; Optimization of the absorption columns in the acetone recovery at the Filter Tow production by phenomenological studies and statistical analysis.

Nasser Junior, Roberto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 13/11/2009 Português
Relevância na Pesquisa
65.93%
A absorção é a etapa determinante da recuperação de acetona no Filter Tow, por reduzir a emissão de acetona e trazer melhorias à economia. Por isso, ela constitui o objeto deste estudo, que inclui desde a revisão dos conceitos fenomenológicos, considerando a escolha do melhor modelo de equilíbrio líquido-vapor, passando pela execução dos balanços coerentes de massa e o estabelecimento da Fotografia da situação original, relatando um caso complexo de transposição de pratos para recheios. Contudo, a operação das colunas de absorção é influenciada por outras variáveis de caráter desconhecido, ruídos em relação à fenomenologia, o que se pretende avaliar, justificando-se desenvolver estudo para avaliar seus efeitos. Com o objetivo geral de otimizar absorção, uma análise estatística foi executada a partir do levantamento de dados operacionais, utilizando todas suas variáveis, sejam as fenomenológicas, como os ruídos, com o objetivo específico de obter modelos empíricos que complementem as simulações fenomenológicas, aumentando sua abrangência. Para a execução da análise estatística, os conjuntos de dados históricos foram levantados e validados pelos balanços coerentes de massa e pela Fotografia...

Morphometric study by image analysis of Ag-stained nucleoli in thyroids bearing proliferating lesions

Abdo-Banhos, C. R.; Cordeiro, J. A.; Rosa, C. S.; Bicudo, H. E M C
Tipo: Artigo de Revista Científica Formato: 37-43
Português
Relevância na Pesquisa
55.9%
The Ag-NOR staining technique and image analysis were used to evaluate morphological parameters (area, perimeter and axis ratio) in nucleoli from normal thyroids and from thyroids bearing proliferating lesions (carcinomas, adenomas and hyperplasias). Regions with normal appearance located close to adenomatous and carcinomatous regions, in the thyroid of every patient, were also analyzed for comparison with the respective pathological regions and with normal thyroids. Statistical analysis of data for the nucleolar area and perimeter allowed the separation of adenomas and carcinomas from hyperplasias and normal tissue but not the two components in each of these two groups. However, if we look at the numbers, a sequence of increasing nucleolar mean areas in the order: normal, hyperplasia, adenoma and carcinoma may be observed, indicating the sequence of increasing rRNA requirements in these different kinds of cells. The axis ratio that denotes the nucleolar shape (round or oblong) did not show significant differences among tissues, suggesting that shape is not important in the characterization of these pathologies. Differences in nucleolar areas and perimeter between normal and affected regions from each patient were statistically significant for adenomas and carcinomas. When these normal regions were compared with the normal thyroids...

Spontaneous eye blink analysis in the normal individual

Schellini, Silvana Artioli; Sampaio Jr., Amilton A.; Hoyama, Erika; Cruz, Antônio A. V.; Padovani, Carlos R.
Tipo: Artigo de Revista Científica Formato: 239-242
Português
Relevância na Pesquisa
55.89%
Purpose: Spontaneous eye blink activity in the primary eye position and its relationship to age and gender were assessed using digital image processing techniques to quantify blink opening and closing time. Methods: One hundred-and-eighty healthy volunteers (90 males and 90 females), divided into the age groups 0-3, 4-12, 13-20, 21-40, 41-60 and ?60 years old, were evaluated prospectively. They were videotaped digitally in a standard setting and the images were transferred to a personal computer (Macintosh 400) and processed with the iMovie software. Blink opening and closing time were measured at 30 frames/second. The data were then subjected to statistical analysis. Results: The closing time was significantly longer than the opening time for all ages and both genders. Elderly individuals (?41 years old) and women had significantly longer closing times. Conclusion: Image processing techniques made possible the observation of differences in spontaneous eye blink opening and closing time in relation to age and gender. Copyright © 2005 Taylor & Francis LLC.

A statistical analysis of loss factor to determine the energy losses

De Oliveira, M. E.; Boson, D. F A; Padilha-Feltrin, A.
Tipo: info:eu-repo/semantics/conferencepaper
Português
Relevância na Pesquisa
65.85%
Given that the total amount of losses in a distribution system is known, with a reliable methodology for the technical loss calculation, the non-technical losses can be obtained by subtraction. A usual method of calculation technical losses in the electric utilities uses two important factors: load factor and the loss factor. The load factor is usually obtained with energy and demand measurements, whereas, to compute the loss factor it is necessary the learning of demand and energy loss, which are not, in general, prone of direct measurements. In this work, a statistical analysis of this relationship using the curves of a sampling of consumers in a specific company is presented. These curves will be summarized in different bands of coefficient k. Then, it will be possible determine where each group of consumer has its major concentration of points. ©2008 IEEE.

Aplicação das metodologias de analise estatistica e de Analise do Custo do Ciclo de Vida (ACCV) para o estabelecimento de padrões de eficiencia energetica : refrigeradores brasileiros; Application of the methodology of statistical analysis and of life cycle cost analysis (LCCA) to the establishment energy efficiency standards brazilian refrigerators

Herculano Xavier da Silva Junior
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: dissertação de mestrado Formato: application/pdf
Publicado em 28/07/2005 Português
Relevância na Pesquisa
55.99%
o objetivo desta dissertação é discutir a aplicação das metodologias de Análise do Custo do Ciclo de Vida (ACCV) e de Análise Estatística como ferramentas para propor padrões de eficiência energética, complementares às etiquetas (selos) voluntárias já existentes, nos refrigeradores brasileiros de uma porta. Um outro objetivo é estudar o papel desses instrumentos (Selos e Padrões de Eficiência Energética) como meios de fornecer subsídios técnicos para o estabelecimento de níveis máximos de consumo de energia elétrica para equipamentos consumidores de eletricidade comercializados no Brasil. As metodologias ACCV e Análise Estatística permitem avaliar os impactos do aumento de eficiência energética nesses equipamentos, resultando em economias (de energia, financeiras, redução na emissão de dióxido de carbono, etc.) importantes para os consumidores e para o País. Os resultados alcançados nesse estudo apresentam importantes dados para subsidiar discussões mais aprofundadas com os fabricantes e governo para estipular padrões mínimos de eficiência energética para os refrigeradores brasileiros. Uma das importantes conclusões é que, apesar de existirem outras metodologias como a Análise Estatística, a ACCV que leva em conta os custos tecnológicos permite que se conheça melhor o mercado (custos...

Statistical analysis of compressive strength of concrete specimens

Aguiar, J. L. Barroso de; Veiga, E.; Oliveira, Pedro
Fonte: Elmaarefa Printing House Publicador: Elmaarefa Printing House
Tipo: info:eu-repo/semantics/conferenceobject
Publicado em //2003 Português
Relevância na Pesquisa
65.89%
This paper presents the statistical analysis of compressive strength of concrete specimens delivered in a laboratory of Northern of Portugal. Three types of concretes were analyzed defined as C20, C25 and C30. In the study we used the results of three years, 1995 to 1997. The one-sample Kolmogorov-Smirnov Test was used to verify the normal distribution of the strength results. The results presented in this paper are important for predicting the performance of structural elements and for calculating resistance factors for limit state design codes. As concrete is made in majority on site, conformity is more difficult than for other construction materials produced on factories. For the first analysis the concrete applied on the different sites were separated in groups. A total of 82 groups of concrete produced in 20 sites, were analyzed. We verified that in about 32% of the groups the characteristic compressive strength established for the design was not achieved. For the second analysis the total results were considered, without separation by site or by group. When the exigency was classes C20 or C25, the characteristic compressive strength was below the exigency. On the contrary, for the concrete mentioned as C30, the characteristic compressive strength was above the exigency.

Statistical analysis and modeling of optical transport networks; Análise estatística e modelação de redes óticas de transporte

Routray, Sudhir Kumar
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
65.99%
Statistical analysis and modeling of networks is now an integral part of network science and engineering. In case of optical transport networks (OTNs), it can be used for the planning and dimensioning when the complete information is not available or is difficult to process. The core networks around the world today are almost optical and they form the backbone of the Internet. Therefore, the statistical characteristics of these networks must be studied to understand their nature and to estimate their parameters. In science and technology, network analysis and modeling are used for several purposes such as the analysis of their stability, reliability and long term evolution. Knowledge of the statistical models helps in the estimation of several critical parameters of the networks. The work presented in this thesis is focused on the analysis and modeling of link lengths and shortest path lengths in OTNs. The parameters used in the models presented in this thesis can be estimated from the very basic information of the networks such as the coverage area and the number of nodes, both of which can be found from the node locations. These models can be applied to estimate key parameters of the networks. In this thesis, we have shown that the link lengths of the OTNs follow general extreme value distribution. The parameters of the proposed distribution can be estimated from the average link lengths of the networks. We develop expressions for the average link lengths of OTNs which can be estimated with an average error of just 11%. We apply the developed model to estimate link length dependent parameters in OTNs. We show that the shortest path lengths of the OTNs follow Johnson SB distribution. We estimate the parameters of the developed model from the convex area and the number of nodes of the network. We also apply this model to estimate several shortest path-dependent parameters in OTNs.; A análise estatística e modelação de redes é atualmente uma parte integrante da ciência e engenharia de redes. No caso das redes óticas de transporte (OTN)...

Average mass scan of the total ion chromatogram versus percentage chemical composition in multivariate statistical comparison of complex volatile mixtures

Radulovi?,Niko S.; Blagojevi?,Polina D.; Skropeta,Danielle
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 Português
Relevância na Pesquisa
55.94%
The analysis of complex volatile mixtures by gas chromatography-mass spectrometry (GC-MS) is a time-consuming process. It involves separation and identification of the components based on their retention times and fragmentation patterns, followed by determination of their relative percentages from integration of their peak areas. Herein we show that multivariate statistical analysis of the relative abundances of the m/z values obtained from the average mass scans (AMS) of the complex mixture is a faster and potentially more reliable method of assessing these mixtures. To achieve this, 15 model complex mixtures, were prepared comprising varying amounts of 10 different constituents. The AMS profile and chemical composition of each mixture were compared to one another using agglomerative hierarchical cluster analysis and principal component analysis. The results obtained strongly suggest that multivariate statistical analysis of AMS profiles is a promising, time saving and reliable tool for analyzing complex volatile mixtures, in particular essential oils.

A multivariate statistical analysis of the QSAR of 2-(substituted phenyl)indan-1,3-diones with hypolipidemic activity

Silva,Aluizio G. da; Ramos,Mozart N.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2012 Português
Relevância na Pesquisa
65.89%
Electronic descriptors obtained from AM1 molecular orbital calculations were employed, along with the empirical parameters log P and ?, in a multivariate statistical analysis of the quantitative structure-activity relationships (QSAR) in a group of sixteen 2-(substituted phenyl)indan- 1,3-diones possessing hypolipidemic activities. AM1 descriptors were obtained both for the isolated molecule model and, to simulate the solvent effect, for the COSMO model (conductor-like screening model) in our QSAR analysis. From sixteen studied derivatives, three were excluded from the set of molecules used in the model building stage in order to serve as a test set. In general, the results obtained from this test set validated our quantitative models, which were based on linear regressions and principal component analysis (PCA). From these results, new derivatives were predicted to be more potent hypolipidemic agents than the indan-1,3-diones for which experimental activities were determined. For instance, our results suggest that 2-(ortho-hydroxy-phenyl)indan-1,3-dione is a potential candidate for new experimental screening studies for reducing serum cholesterol and triglyceride levels.

A multivariate statistical analysis of the QSAR of 2-(substituted phenyl)indan-1,3-diones with hypolipidemic activity

Silva,Aluizio G. da; Ramos,Mozart N.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2012 Português
Relevância na Pesquisa
65.89%
Electronic descriptors obtained from AM1 molecular orbital calculations were employed, along with the empirical parameters log P and ?, in a multivariate statistical analysis of the quantitative structure-activity relationships (QSAR) in a group of sixteen 2-(substituted phenyl)indan- 1,3-diones possessing hypolipidemic activities. AM1 descriptors were obtained both for the isolated molecule model and, to simulate the solvent effect, for the COSMO model (conductor-like screening model) in our QSAR analysis. From sixteen studied derivatives, three were excluded from the set of molecules used in the model building stage in order to serve as a test set. In general, the results obtained from this test set validated our quantitative models, which were based on linear regressions and principal component analysis (PCA). From these results, new derivatives were predicted to be more potent hypolipidemic agents than the indan-1,3-diones for which experimental activities were determined. For instance, our results suggest that 2-(ortho-hydroxy-phenyl)indan-1,3-dione is a potential candidate for new experimental screening studies for reducing serum cholesterol and triglyceride levels.

Sisvar: a computer statistical analysis system

Ferreira,Daniel Furtado
Fonte: Editora da Universidade Federal de Lavras Publicador: Editora da Universidade Federal de Lavras
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 Português
Relevância na Pesquisa
55.92%
Sisvar is a statistical analysis system, first released in 1996 although its development began in 1994. The first version was done in the programming language Pascal and compiled with Borland Turbo Pascal 3. Sisvar was developed to achieve some specific goals. The first objective was to obtain software that could be used directly on the statistical experimental course of the Department of Exact Science at the Federal University of Lavras. The second objective was to initiate the development of a genuinely Brazilian free software program that met the demands and peculiarities of research conducted in the country. The third goal was to present statistical analysis software for the Brazilian scientific community that would allow research results to be analyzed efficiently and reliably. All of the initial goals were achieved. Sisvar gained acceptance by the scientific community because it provides reliable, accurate, precise, simple and robust results, and allows users a greater degree of interactivity.

Evaluation via multivariate techniques of scale factor variability in the rietveld method applied to quantitative phase analysis with X ray powder diffraction

Oliveira,Terezinha Ferreira de; Avillez,Roberto Ribeiro de; Epprecht,Eugenio Kahn; Queiroz,Joaquim Carlos Barbosa
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2006 Português
Relevância na Pesquisa
55.82%
The present work uses multivariate statistical analysis as a form of establishing the main sources of error in the Quantitative Phase Analysis (QPA) using the Rietveld method. The quantitative determination of crystalline phases using x ray powder diffraction is a complex measurement process whose results are influenced by several factors. Ternary mixtures of Al2O3, MgO and NiO were prepared under controlled conditions and the diffractions were obtained using the Bragg-Brentano geometric arrangement. It was possible to establish four sources of critical variations: the experimental absorption and the scale factor of NiO, which is the phase with the greatest linear absorption coefficient of the ternary mixture; the instrumental characteristics represented by mechanical errors of the goniometer and sample displacement; the other two phases (Al2O3 and MgO); and the temperature and relative humidity of the air in the laboratory. The error sources excessively impair the QPA with the Rietveld method. Therefore it becomes necessary to control them during the measurement procedure.

Statistical analysis of acoustic emission signals generated during turning of a metal matrix composite

Mukhopadhyay,C. K.; Jayakumar,T.; Raj,Baldev; Venugopal,S.
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 Português
Relevância na Pesquisa
65.89%
Acoustic emission technique (AET) has been used to monitor the progress of tool wear during turning of silicon carbide (20 wt.%) dispersed Al alloy metal matrix composite. Acoustic emission (AE) signals generated beyond a specific cutting distance increase abruptly. Statistical analysis based on assumed ? distribution of AE energy showed that skewness and kurtosis vary with cutting time. Comparison of these results with bparameter of amplitude distribution of AE hits presented in an earlier investigation has shown that while b-parameter is useful for monitoring tool wear up to 0.4 mm, skewness and kurtosis can better monitor the wear beyond that. Uncertainty measurement of AE energy for different cutting distances was determined as per ISO GUM. The combined uncertainty for the measurement of AE energy lies in the range of 0.38 to 1.69, with higher values for the cutting distance between 213.8 mm and 454.5 mm. Different parameters such as skewness and kurtosis of the statistical distribution, b-parameter of amplitude distribution and uncertainties can be used in a complimentary manner for comprehensive evaluation of tool wear.

Normality Tests for Statistical Analysis: A Guide for Non-Statisticians

Ghasemi, Asghar; Zahediasl, Saleh
Fonte: Kowsar Publicador: Kowsar
Tipo: text
Português
Relevância na Pesquisa
55.89%
Statistical errors are common in scientific literature and about 50% of the published articles have at least one error. The assumption of normality needs to be checked for many statistical procedures, namely parametric tests, because their validity depends on it. The aim of this commentary is to overview checking for normality in statistical analysis using SPSS.

Statistical tools to uncover genetic architecture of tick resistance using highdensity oligonucleotide gene expression microarrays.

CARDOSO, F. F.; GIACHETTO, P. F.; YAMAGISHI, M. E. B.; HIGA, R. H.
Fonte: In: SÃO PAULO ADVANCED SCHOOL OF SCIENCE, 1., 2011, São Carlos, SP. Advances in the knowledge of parasite resistance of ruminant hosts and parasites: proceedings. São Carlos, SP: Embrapa Pecuária Sudeste, 2011. Publicador: In: SÃO PAULO ADVANCED SCHOOL OF SCIENCE, 1., 2011, São Carlos, SP. Advances in the knowledge of parasite resistance of ruminant hosts and parasites: proceedings. São Carlos, SP: Embrapa Pecuária Sudeste, 2011.
Tipo: artigo em anais de congresso (alice) Formato: p. 34-38.
Português
Relevância na Pesquisa
55.85%
The aim of this paper is to present procedures and tools used for quality control and statistical analysis of high-density microarray (Affymetrix GeneChip®) to search for genes that may be differentially expressed and that may provide clues to unravel parasite resistance.; 2011

Application of public-domain statistical analysis software for evaluation and comparison of comet assay data

Verde, Pablo Emílio; Monserrat, Laura Alicia Geracitano; Amado, Lílian Lund; Rosa, Carlos Eduardo da; Bianchini, Adalto; Monserrat, José María
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
55.97%
A novel approach for statistical analysis of comet assay data (i.e.: tail moment) is proposed, employing public-domain statistical software, the R system. The analytical strategy takes into account that the distribution of comet assay data, like the tail moment, is usually skewed and do not follow a normal distribution. Probability distributions used to model comet assay data included: the Weibull, the exponential, the logistic, the normal, the log normal and log-logistic distribution. In this approach it was also considered that heterogeneity observed among experimental units is a random feature of the comet assay data. This statistical model can be characterized with a location parameter mij, a scale parameter r and a between experimental units variability parameter ?. In the logarithmic scale, the parameter mij depends additively on treatment and random effects, as follows: log(mij) = a0 + a1xij + bi, where exp(a0) represents approximately the mean value of the control group, exp(a1) can be interpreted as the relative risk of damage with respect to the control group, xij is an indicator of experimental group and exp(bi) is the individual risk effects assume to follows a Gamma distribution with mean 1 and variance ?. Model selection is based on Akaike’s information criteria (AIC). Real data coming from comet analysis of blood samples taken from the flounder Paralichtys orbignyanus (Teleostei: Paralichtyidae) and from samples of cells suspension obtained from the estuarine polychaeta Laeonereis acuta (Nereididae) were employed. This statistical approach showed that the comet assay data should be analyzed under a modeling framework that take into account the important features of these measurements. Model selection and heterogeneity between experimental units play central points in the analysis of these data.