Estudo Comparativo de gráaficos de probabilidade normal para Anáalise de experimentos fatoriais não replicados

Two-level factorial designs are widely used in industrial experimentation. However, many factors in such a design require a large number of runs to perform the experiment, and too many replications of the treatments may not be feasible, considering limitations of resources and of time, making it expensive. In these cases, unreplicated designs are used. But, with only one replicate, there is no internal estimate of experimental error to make judgments about the significance of the observed efects. One of the possible solutions for this problem is to use normal plots or half-normal plots of the efects. Many experimenters use the normal plot, while others prefer the half-normal plot and, often, for both cases, without justification. The controversy about the use of these two graphical techniques motivates this work, once there is no register of formal procedure or statistical test that indicates \which one is best". The choice between the two plots seems to be a subjective issue. The central objective of this master's thesis is, then, to perform an experimental comparative study of the normal plot and half-normal plot in the context of the analysis of the 2k unreplicated factorial experiments. This study involves the construction of simulated scenarios, in which the graphics performance to detect significant efects and to identify outliers is evaluated in order to verify the following questions: Can be a plot better than other? In which situations? What kind of information does a plot increase to the analysis of the experiment that might complement those provided by the other plot? What are the restrictions on the use of graphics? Herewith, this work intends to confront these two techniques; to examine them simultaneously in order to identify similarities, diferences or relationships that contribute to the construction of a theoretical reference to justify or to aid in the experimenter's decision about which of the two graphical techniques to use and the reason for this use. The simulation results show that the half-normal plot is better to assist in the judgement of the efects, while the normal plot is recommended to detect outliers in the data

An extension of the half-normal distribution

In this paper we introduce a new distribution, namely, the slashed half-normal distribution and it can be seen as an extension of the half-normal distribution. It is shown that the resulting distribution has more kurtosis than the ordinary half-normal distribution. Moments and some properties are derived for the new distribution. Moment estimators and maximum likelihood estimators can computed using numerical procedures. Results of two real data application are reported where model fitting is implemented by using maximum likelihood estimation. The applications illustrate the better performance of the new distribution.

Evaluation of Gap-Graded Asphalt Concrete Mixtures Part II: Statistical Design and Analysis, HR-157, 1973

This report presents the results of a comparative laboratory study between well- and gap-graded aggregates used in asphalt concrete paving mixtures. A total of 424 batches of asphalt concrete mixtures and 3, 960 Marshall and Hveem specimens were examined. The main thrust of the statistical analysis conducted in this experiment was in the calibration study and in Part I of the experiment. In the former study, the compaction procedure between the Iowa State University Lab and the Iowa Highway Commission Lab was calibrated. By an analysis of the errors associated with the measurements we were able to separate the "preparation" and "determination" errors for both laboratories as well as develop the calibration curve which describes the relationship between the compaction procedures at the two labs. In Part I, the use of a fractional factorial design in a split plot experiment in measuring the effect of several factors on asphalt concrete strength and weight was exhibited. Also, the use of half normal plotting techniques for indicating significant factors and interactions and for estimating errors in experiments with only a limited number of observations was outlined,

The exponentiated generalized gamma distribution with application to lifetime data

A four-parameter extension of the generalized gamma distribution capable of modelling a bathtub-shaped hazard rate function is defined and studied. The beauty and importance of this distribution lies in its ability to model monotone and non-monotone failure rate functions, which are quite common in lifetime data analysis and reliability. The new distribution has a number of well-known lifetime special sub-models, such as the exponentiated Weibull, exponentiated generalized half-normal, exponentiated gamma and generalized Rayleigh, among others. We derive two infinite sum representations for its moments. We calculate the density of the order statistics and two expansions for their moments. The method of maximum likelihood is used for estimating the model parameters and the observed information matrix is obtained. Finally, a real data set from the medical area is analysed.

Densidade populacional de raposa-do-campo Lycalopex vetulus (Carnivora, Canidae) em áreas de pastagem e campo sujo, Campinápolis, Mato Grosso, Brasil

Diante da crescente descaracterização do Bioma Cerrado em função da expansão da fronteira agropecuária na região central do Brasil, torna-se importante avaliar a capacidade de adaptação das espécies ao ambiente antropizado. Neste sentido, este trabalho foi desenvolvido com o objetivo de estimar e comparar a densidade populacional da raposa-do-campo Lycalopex vetulus (Lund, 1842) em duas áreas com diferentes graus de alteração, pastagem e campo sujo, em Campinápolis, Mato Grosso. Para tanto, no período entre agosto a novembro de 2005, foram efetuados censos noturnos ao longo de transectos lineares, totalizando percursos de 129,8 km na área de campo sujo e 62,08 km na área de pastagem. Estimativas de densidade populacional foram geradas utilizando o programa Distance 5.0, sendo que o modelo e ajuste mais adequados aos dados foram half-normal + hermite. Foram obtidas 23 e 52 detecções de raposas-do-campo nas áreas de campo sujo e pastagem, respectivamente. A densidade populacional de raposa-do-campo na área de pastagem (D=4,28 indivíduos/km²; IC=2,69 - 6,82) foi maior que na área de campo sujo (D=1,21 indivíduos/km²; IC=0,73 - 2,01), fato que deve estar relacionado, principalmente, com a disponibilidade de alimento e redução de potenciais predadores. Por apresentar uma dieta composta principalmente de cupins, especialmente os dos gêneros Syntermes e Cornitermes, a raposa-do-campo encontra na área de pastagem uma base alimentar abundante e estável. Além disto, a simplificação ambiental, em função da implantação de pastagens acaba por reduzir, ou até mesmo eliminar, animais que são potenciais predadores de raposas-do-campo, como Chrysocyon brachyurus (Illiger, 1815), favorecendo o aumento da densidade populacional da espécie neste tipo de ambiente. Por fim, características adaptativas apresentadas pela raposa-do-campo têm permitido que esta espécie sobreviva, inclusive apresentando elevada densidade populacional, em áreas de pastagem utilizadas para a criação de gado, em Campinápolis, Mato Grosso, onde a vegetação original era Cerrado.

Effects of phthalic acid esters on the liver and thyroid

The effects, over periods from 3 days to 9 months of administration, of diets containing di-2-ethylhexyl phthalate are very similar to those observed in rats administered diets containing hypolipidemic drugs such as clofibrate. Changes occur in a characteristic order commencing with alterations in the distribution of lipid within the liver, quickly followed by proliferation of hepatic peroxisomes and induction of the specialized P-450 isoenzyme(s) catalyzing omega oxidation of fatty acids. There follows a phase of mild liver damage indicated by induction of glucose-6-phosphatase activity and a loss of glycogen, eventually leading to the formation of enlarged lysosomes through autophagy and the accumulation of lipofuscin. Associated changes are found in the kidney and thyroid. The renal changes are limited to the proximal convoluted tubules and are generally similar to changes found in the liver. The effects on the thyroid are more marked. Although the levels of thyroxine in plasma fail to about half normal values, serum triiodothyronine remains close to normal values while the appearance of the thyroid varies, very marked hyperactivity being noted 7 days after commencement of treatment, this is less marked at 14 days, but even after 9 months treatment there is clear cut evidence for hyperactivity with colloid changes which indicate this has persisted for some time. Straight chain analogs of di-2-ethylhexyl phthalate, di-n-hexyl phthalate and di-n-oxtyl phthalate differ entirely in their short-term effects on the liver and kidney but have similar effects on the thyroid. The short-term in vivo hepatic effects of the three phthalate esters can be reproduced in hepatocytes in tissue culture. All three phthalate esters, as well as clofibrate, have early marked effects on the metabolism of fatty acids in isolated hepatocytes. The nature of these changes is such as to increase storage of lipid in the liver. A hypothesis is presented to explain the progress from these initial metabolic effects to the final formation of liver tumors.

A New Class of Non Negative Distributions Generated by Symmetric Distributions

In this article, we study a new class of non negative distributions generated by the symmetric distributions around zero. For the special case of the distribution generated using the normal distribution, properties like moments generating function, stochastic representation, reliability connections, and inference aspects using methods of moments and maximum likelihood are studied. Moreover, a real data set is analyzed, illustrating the fact that good fits can result.

von Willebrand factor-mediated platelet adhesion is critical for deep vein thrombosis in mouse models

Deep vein thrombosis (DVT) and its complication, pulmonary embolism, are frequent causes of disability and mortality. Although blood flow disturbance is considered an important triggering factor, the mechanism of DVT initiation remains elusive. Here we show that 48-hour flow restriction in the inferior vena cava (IVC) results in the development of thrombi structurally similar to human deep vein thrombi. von Willebrand factor (VWF)-deficient mice were protected from thrombosis induced by complete (stasis) or partial (stenosis) flow restriction in the IVC. Mice with half normal VWF levels were also protected in the stenosis model. Besides promoting platelet adhesion, VWF carries Factor VIII. Repeated infusions of recombinant Factor VIII did not rescue thrombosis in VWF(-/-) mice, indicating that impaired coagulation was not the primary reason for the absence of DVT in VWF(-/-) mice. Infusion of GPG-290, a mutant glycoprotein Ib?-immunoglobulin chimera that specifically inhibits interaction of the VWF A1 domain with platelets, prevented thrombosis in wild-type mice. Intravital microscopy showed that platelet and leukocyte recruitment in the early stages of DVT was dramatically higher in wild-type than in VWF(-/-) IVC. Our results demonstrate a pathogenetic role for VWF-platelet interaction in flow disturbance-induced venous thrombosis.

Cognitive-Behavioural Analysis System of Psychotherapy (CBASP), a drug, or their combination: differential therapeutics for persistent depressive disorder: a study protocol of an individual participant data network meta-analysis.

INTRODUCTION Despite important advances in psychological and pharmacological treatments of persistent depressive disorders in the past decades, their responses remain typically slow and poor, and differential responses among different modalities of treatments or their combinations are not well understood. Cognitive-Behavioural Analysis System of Psychotherapy (CBASP) is the only psychotherapy that has been specifically designed for chronic depression and has been examined in an increasing number of trials against medications, alone or in combination. When several treatment alternatives are available for a certain condition, network meta-analysis (NMA) provides a powerful tool to examine their relative efficacy by combining all direct and indirect comparisons. Individual participant data (IPD) meta-analysis enables exploration of impacts of individual characteristics that lead to a differentiated approach matching treatments to specific subgroups of patients. METHODS AND ANALYSIS We will search for all randomised controlled trials that compared CBASP, pharmacotherapy or their combination, in the treatment of patients with persistent depressive disorder, in Cochrane CENTRAL, PUBMED, SCOPUS and PsycINFO, supplemented by personal contacts. Individual participant data will be sought from the principal investigators of all the identified trials. Our primary outcomes are depression severity as measured on a continuous observer-rated scale for depression, and dropouts for any reason as a proxy measure of overall treatment acceptability. We will conduct a one-step IPD-NMA to compare CBASP, medications and their combinations, and also carry out a meta-regression to identify their prognostic factors and effect moderators. The model will be fitted in OpenBUGS, using vague priors for all location parameters. For the heterogeneity we will use a half-normal prior on the SD. ETHICS AND DISSEMINATION This study requires no ethical approval. We will publish the findings in a peer-reviewed journal. The study results will contribute to more finely differentiated therapeutics for patients suffering from this chronically disabling disorder. TRIAL REGISTRATION NUMBER CRD42016035886.

A nova família de distribuições odd log-logística: teoria e aplicações

Neste trabalho, foi proposta uma nova família de distribuições, a qual permite modelar dados de sobrevivência quando a função de risco tem formas unimodal e U (banheira). Ainda, foram consideradas as modificações das distribuições Weibull, Fréchet, half-normal generalizada, log-logística e lognormal. Tomando dados não-censurados e censurados, considerou-se os estimadores de máxima verossimilhança para o modelo proposto, a fim de verificar a flexibilidade da nova família. Além disso, um modelo de regressão locação-escala foi utilizado para verificar a influência de covariáveis nos tempos de sobrevida. Adicionalmente, conduziu-se uma análise de resíduos baseada nos resíduos deviance modificada. Estudos de simulação, utilizando-se de diferentes atribuições dos parâmetros, porcentagens de censura e tamanhos amostrais, foram conduzidos com o objetivo de verificar a distribuição empírica dos resíduos tipo martingale e deviance modificada. Para detectar observações influentes, foram utilizadas medidas de influência local, que são medidas de diagnóstico baseadas em pequenas perturbações nos dados ou no modelo proposto. Podem ocorrer situações em que a suposição de independência entre os tempos de falha e censura não seja válida. Assim, outro objetivo desse trabalho é considerar o mecanismo de censura informativa, baseado na verossimilhança marginal, considerando a distribuição log-odd log-logística Weibull na modelagem. Por fim, as metodologias descritas são aplicadas a conjuntos de dados reais.

O comprimento descritivo mínimo na amostragem por transectos lineares

Apresenta·se um breve resumo histórico da evolução da amostragem por transectos lineares e desenvolve·se a sua teoria. Descrevemos a teoria de amostragem por transectos lineares, proposta por Buckland (1992), sendo apresentados os pontos mais relevantes, no que diz respeito à modelação da função de detecção. Apresentamos uma descrição do princípio CDM (Rissanen, 1978) e a sua aplicação à estimação de uma função densidade por um histograma (Kontkanen e Myllymãki, 2006), procedendo à aplicação de um exemplo prático, recorrendo a uma mistura de densidades. Procedemos à sua aplicação ao cálculo do estimador da probabilidade de detecção, no caso dos transectos lineares e desta forma estimar a densidade populacional de animais. Analisamos dois casos práticos, clássicos na amostragem por distâncias, comparando os resultados obtidos. De forma a avaliar a metodologia, simulámos vários conjuntos de observações, tendo como base o exemplo das estacas, recorrendo às funções de detecção semi-normal, taxa de risco, exponencial e uniforme com um cosseno. Os resultados foram obtidos com o programa DISTANCE (Thomas et al., in press) e um algoritmo escrito em linguagem C, cedido pelo Professor Doutor Petri Kontkanen (Departamento de Ciências da Computação, Universidade de Helsínquia). Foram desenvolvidos programas de forma a calcular intervalos de confiança recorrendo à técnica bootstrap (Efron, 1978). São discutidos os resultados finais e apresentadas sugestões de desenvolvimentos futuros. ABSTRACT; We present a brief historical note on the evolution of line transect sampling and its theoretical developments. We describe line transect sampling theory as proposed by Buckland (1992), and present the most relevant issues about modeling the detection function. We present a description of the CDM principle (Rissanen, 1978) and its application to histogram density estimation (Kontkanen and Myllymãki, 2006), with a practical example, using a mixture of densities. We proceed with the application and estimate probability of detection and animal population density in the context of line transect sampling. Two classical examples from the literature are analyzed and compared. ln order to evaluate the proposed methodology, we carry out a simulation study based on a wooden stakes example, and using as detection functions half normal, hazard rate, exponential and uniform with a cosine term. The results were obtained using program DISTANCE (Thomas et al., in press), and an algorithm written in C language, kindly offered by Professor Petri Kontkanen (Department of Computer Science, University of Helsinki). We develop some programs in order to estimate confidence intervals using the bootstrap technique (Efron, 1978). Finally, the results are presented and discussed with suggestions for future developments.

Resident tissue macrophages within the normal rat iris lack immunosuppressive activity and are effective antigen-presenting cells

Despite extensive study of the numerous immunoregulatory mechanisms that contribute to the immune-privileged nature of the anterior chamber (AC) of the eye, little is known of the functional nature of antigen-presenting cells (APC) present in the tissues adjoining the AC. In the present study, we have compared the antigen-presenting capacity of dendritic cells (DC) and macrophages isolated from the normal rat iris. Whereas iris DC exhibited a potent ability to stimulate resting allogeneic T cells in MLR cultures (an in-vitro correlate of the ability to induce primary T cell responses), resident iris macrophages displayed negligible MLR-stimulatory capacity. Significantly, iris macrophages could efficiently elicit proliferation of primed antigen-specific T cells (an in-vitro correlate of the ability to act as local APC in secondary responses). This antigen-presenting activity was approximately half that of fully mature iris DC and considerably greater than that of freshly isolated iris DC. A key contributor to the effectiveness of resident iris macrophage antigen presentation was considered to be the absence of lymphocytostatic control of T cell proliferation exerted by these cells. The results indicate dichotomous but complementary roles for DC (immune surveillance) and macrophages (local antigen presentation in secondary responses) in this tissue.

Tooth-wear patterns in subjects with Class II Division 1 malocclusion and normal occlusion

Introduction: The aim of this study was to investigate the prevalence of tooth wear in adolescents with Class II malocclusion, compared with those with normal occlusion. Methods: The sample consisted of dental casts obtained from 310 subjects, divided into 3 groups: group 1, 110 subjects with normal occlusion (mean age, 13.51 years); group 2, 100 complete Class II Division 1 patients (mean age, 13.44 years); and group 3, 100 half-cusp Class II Division 1 patients (mean age, 13.17 years). Dental wear was assessed by using a modified version of the tooth-wear index. The 3 groups were compared by means of the Kruskal-Wallis and Dunn tests, considering the frequency and the severity of wear on each surface of each group of teeth. The level of statistical significance was set at 5%. Results: The normal occlusion group had statistically greater tooth wear on the palatal surfaces of the maxillary central incisors and the incisal surfaces of the maxillary canines than the corresponding surfaces in both Class II malocclusion groups. The complete and half-cusp Class II Division 1 malocclusion groups had statistically greater tooth wear on the occlusal surfaces of the maxillary second premolar and first molar, the occlusal surfaces of the mandibular premolars, and the buccal surfaces of the mandibular posterior teeth compared with the normal occlusion group. The half-cusp Class II Division 1 malocclusion group had significantly greater tooth wear on the incisal surfaces of the mandibular incisors compared with the complete Class II Division 1 malocclusion group. Conclusions: Subjects with normal occlusion and complete or half-cusp Class II Division 1 malocclusions have different tooth-wear patterns. Tooth wear on the malocclusion subjects should not be considered pathologic but rather consequent to the different interocclusal tooth arrangement. (Am J Orthod Dentofacial Orthop 2010; 137: 14. e1-14.e7)

Determination of reference values for glucose tolerance, insulin tolerance, and insulin sensitivity tests in clinically normal cats

Objective-To determine reference values and test variability for glucose tolerance tests (GTT), insulin tolerance tests (ITT), and insulin sensitivity tests (IST) in cats, Animals-32 clinically normal cats. Procedure-GTT, ITT, and IST were performed on consecutive days. Tolerance intervals tie, reference values) were calculated as means +/- 2.397 SD for plasma glucose and insulin concentrations, half-life of glucose (T-1/2glucose), rate constants for glucose disappearance (K-glucose and K-itt), and insulin sensitivity index (S-l). Tests were repeated after 6 weeks in 8 cats to determine test variability. Results-Reference values for T-1/2glucose, K-glucose, and fasting plasma glucose and insulin concentrations during GTT were 45 to 74 minutes, 0.93 to 1.54 %/min, 37 to 104 mg/dl, and 2.8 to 20.6 muU/ml, respectively. Mean values did not differ between the 2 tests. Coefficients of variation for T-1/2glucose, K-glucose, and fasting plasma glucose and insulin concentrations were 20, 20, 11, and 23%, respectively. Reference values for K-itt were 1.14 to 7.3%/min, and for S-l were 0.57 to 10.99 x 10(-4) min/muU/ml. Mean values did not differ between the 2 tests performed 6 weeks apart, Coefficients of variation for K-itt and S-l were 60 and 47%, respectively. Conclusions and Clinical Relevance-GTT, ITT, and IST can be performed in cats, using standard protocols. Knowledge of reference values and test variability will enable researchers to better interpret test results for assessment of glucose tolerance, pancreatic beta -cell function, and insulin sensitivity in cats.

Dietary chromium tripicolinate supplementation reduces glucose concentrations and improves glucose tolerance in normal-weight cats

The effect of dietary chromium supplementation on glucose and insulin metabolism in healthy, non-obese cats was evaluated. Thirty-two cats were randomly divided into four groups and fed experimental diets consisting of a standard diet with 0 ppb (control), 150 ppb, 300 ppb, or 600 ppb added chromium as chromium tripicolinate. Intravenous glucose tolerance, insulin tolerance and insulin sensitivity tests with minimal model analysis were performed before and after 6 weeks of feeding the test diets. During the glucose tolerance test, glucose concentrations, area under the glucose concentration-time curve, and glucose half-life (300 ppb only), were significantly lower after the trial in cats supplemented with 300 ppb and 600 ppb chromium, compared with values before the trial. Fasting glucose concentrations measured on a different day in the biochemistry profile were also significantly lower after supplementation with 600 ppb chromium. There were no significant differences in insulin concentrations or indices in either the glucose or insulin tolerance tests following chromium supplementation, nor were there any differences between groups before or after the dietary trial. Importantly, this study has shown a small but significant, dose-dependent improvement in glucose tolerance in healthy, non-obese cats supplemented with dietary chromium. Further long-term studies are warranted to determine if the addition of chromium to feline diets is advantageous. Cats most likely to benefit are those with glucose intolerance and insulin resistance from lack of exercise, obesity and old age. Healthy cats at risk of glucose intolerance and diabetes from underlying low insulin sensitivity or genetic factors may also benefit from long-term chromium supplementation. (C) 2002 ESFM and AAFP.