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P.ORTEGA-VERDUGO1 S.GUZMAN-AMSTRONG1 D. COBB1, D.V.DAWSON1, J.KOLKER1, M.HERNANDEZ1, J.WARREN 1University of Iowa, Iowa City, USA. NA

The formulation of log-linear models within the framework of Generalized Linear Models offers new possibilities in modeling categorical data. The resulting models are not restricted to the analysis of contingency tables in terms of ordinary hierarchical interactions. Such models are considered as the family of nonstandard log-linear models. The problem that can arise is an ambiguous interpretation of parameters. In the current paper this problem is solved by looking at the effects coded in the design matrix and determining the numerical contribution of single effects. Based on these results, stepwise approaches are proposed in order to achieve parsimonious models. In addition, some testing strategies are presented to test such (eventually non-nested) models against each other. As a result, a whole interpretation framework is elaborated to examine nonstandard log-linear models in depth.

This thesis deals with regression analysis of experimentally measured data of processed cheese. There is a polynomial regression used. The choice of regressors is based on Stepwise Regression and Mallows's Statistics. The estimation of the mean value is used to find the best mixture of the emulsifying salts with regards to the observed characteristic of the processed cheese. Analysis of the experiment and its results are well documented graphically.

[pt] Um dos principais problemas para a expansão do uso da energia eólica é a escassez de dados. No Brasil, exige-se um histórico de pelo menos 30 anos de produção para a certificação de um parque eólico. No entanto, é muito improvável que esses dados estejam disponíveis. Um recurso frequente é o de utilizar um histórico de medidas locais com uma duração bastante inferior (por exemplo 2 anos) e estendê-lo para 30 anos através do uso de modelos estatísticos. O objetivo dessa dissertação é propor e estudar o desempenho de uma metodologia de extensão de histórico baseada em um modelo de regressão linear. Como ilustração, a metodologia foi aplicada a 4 parques eólicos localizados no nordeste do Brasil. / [en] One of the main problems for the expansion for the use of wind energy is the lack of data. In Brazil, it is required a historic data of at least 30 years of production for the certification of a wind farm. However, is very unlikely that these data is available. A frequent use is to use historic data of local measurements with a short duration (2 years for example) e extend for 30 years through the use of statistical models. The objective of this dissertation is to propose e study the performance of a methodology for the historic data extension based on a linear regression model. As an illustration, the methodology was applied to 4 wind farms located on the northeast of Brazil.

Dans le cadre de cette étude, il est question de prédire les primes de risque de marché pour les États-Unis et le Canada sur un horizon d’un mois en se basant sur les données économiques des 20 dernières années. En se basant sur les modèles élaborés précédemment dans la littérature, ce mémoire a pour but d’effectuer des prévisions plus précises que celles générées précédemment. Ainsi, on observe que l’ensemble des modèles retenus, tant univariés, multivariés ou par agrégation sectorielle obtiennent un pouvoir explicatif supérieur au modèle naïf, et ce tant pour le marché américain que le marché canadien. Pour le marché américain, le modèle multivarié Stepwise Backward obtient la meilleure performance du groupe étudié avec un R[indice supérieur 2] de 0.10714 dans un contexte In-Sample et un R[indice supérieur 2] de 0.22284 dans un contexte Out-Of-Sample selon le test de McCracken (2007). Ce modèle permet donc d’expliquer 22.28% de la variation mensuelle de la prime de risque américaine dans le contexte de l’échantillon observé dans cette étude. Le modèle en question est composé des variables économiques représentant les variations mensuelles au niveau de l’inflation, de la masse monétaire M2, ainsi que du dernier taux journalier du mois observé pour les obligations gouvernementales ayant une échéance de deux ans, cinq ans et dix ans. Pour le marché canadien, le modèle multivarié Stepwise Forward obtient la meilleure performance du groupe étudié dans un contexte In-Sample avec un R[indice supérieur 2] de 0.07760 selon le test de McCracken (2007). Cependant, dans un contexte Out-Of-Sample, le modèle de prévision par agrégation sectorielle élaboré à la section 4.4 obtient de loin la meilleure performance avec un R[indice supérieur 2] de 0.17773 selon le test de McCracken (2007), permettant donc d’expliquer 17.77% de la variation mensuelle de la prime de risque canadienne. La performance accrue des modèles de prévision dans un contexte Out-Of-Sample semble provenir d’une meilleure performance notamment dans les premières années d’observation, (2001 à 2007) grâce à l’exclusion des grandes variations affectant les dernières années de la période d’observation (2008 à 2011).

Carbon skeleton of polysubstituted pyroglutamates with three contiguous asymmetric centers was built up in one base-induced coupling/cyclization reaction of £\-sulfonylacetamide with 2-bromo-2-propenoates and has been used as the key step in the formal synthesis of isoguvacine paroxetine, and psudoheliotridane.

In the study of sound identification, land animals such as birds and bats have been well investigated, and so are their habitats. On the other hand, sound making creatures in the ocean are much less researched. In this research, the stress calls of three Holocentridaes, Neoniphon sammara, Myripristis murdjan, and Sargocentron spinosissimum, who are commonly found in coral reefs, were recorded in water tank for analysis of sound characteristics. The averaged characteristic parameters of single pulse among three is around 410 Hz for the peak frequency, 100 Hz for the bandwidth, 0.07 dB/Hz for the slope, and duration of 0.05 s. As for the impulse train, averaged peak frequency is 415 Hz, 55 Hz for the bandwidth, 0.07 dB/Hz for the slope, and duration of 0.5 s. These parameters were first checked by the Kolmogorov-Smirnov Test to identify if each parameter follows normal distribution; the slopes of ascending and descending frequency and the total duration are not in normal distribution. The three parameters were later transferred so as to concentrate variances. Next, analysis of variance was applied on all characteristics to extract the significant parameters (including non transferred and transferred data), which were then tested by Stepwise Discriminat and Back-propagation Network. The identification rate of for single pulse with and without data transfer is 63% and 82% while pulse train is 57% and 73%. Both identification rates were raised up approximately 20% due to the data transfer. Both methods provide an reliable tool for marine sound identification, and the whole process of the study may be applied to another biological identification.

Namaqualand is world renowned for its mass displays of annual wildflowers occurring in highly disturbed areas. Leysera gnaphalodes is a short-lived perennial shrub that encroaches into this wildflower display, lessening the aesthetic appeal. For this reason populations of L. gnaphalodes need to be kept as small as possible. This is usually achieved by tilling the area regularly, but a less disruptive method would be preferable. Alternatives to this approach are explored. The effect of many interacting factors needed to be examined over long periods of time so that alternative management strategies could be evaluated. Ecological modelling was used as it is ideally suited to this purpose. A review of modelling and its application in ecology is given, which includes a description of the modelling process and a discussion of different types of models and their applications. It was hypothesised that grazing and low rainfall, in addition to tilling, could control the population size of L. gnaphalodes. Data was used from an eight-year study conducted to determine the effects of tilling, grazing and environmental factors on the seedbank and population size of L. gnaphalodes. A rule-based mechanistic mathematical model based on the logistic growth curve was constructed to describe the population dynamics of this species. The model-fit was evaluated using Pearson’s correlation coefficients and graphs, and it proved to be a good model. Tilling and low rainfall were both found to be effective in reducing populations of L. gnaphalodes but grazing had no reducing effect. Simulations based on the model were run to test three different basic management strategies under stochastic rainfall conditions. The management strategy, which most effectively controlled the population was to till the lands whenever the population of L. gnaphalodes reaches of exceeds a relative frequency of 45%. Multivariate statistical models were constructed to determine the effects of all of these factors on the population of L. gnaphalodes. Tilling was confirmed to be effective in reducing the population, but grazing was found to have no effect. Low rainfall was also effective in controlling the population but has the disadvantages of being out of management control and also affecting the desirable wildflowers. / Dissertation (MSc (Botany))--University of Pretoria, 2005. / Plant Science / unrestricted

With a large number of unidentified skeletal remains found in South Africa, the development of osteometric standards to determine sex from various bones is crucial. It is imperative that a forensic anthropologist have access to a variety of techniques both morphological and metric, which can be used to establish accurate demographic profiles from complete, fragmentary and/or commingled remains. Standards for South African populations are available for the cranium, humerus, pelvis, femur, tibia, calcaneus, and talus. No research has been done on bones of the forearm, even though they are known through international studies to exhibit sexual dimorphism. The purpose of this research was to develop discriminant function formulae to determine sex from the radius and ulna for a South African population. The sample consisted of 200 male and 200 female skeletons from the Pretoria Bone (University of Pretoria) and Raymond A. Dart (Witwatersrand University) collections. Sixteen standard anthropometric measurements were taken from the radius (9) and ulna (7) and subjected to stepwise and direct discriminant function analysis. Distal breadth, minimum midshaft diameter and maximum head diameter were the best discriminators of sex in the radius, while minimum midshaft diameter and olecranon breadth were selected for the ulna. Classification accuracy for the forearm ranged from 76% to 86%. In summary, the radius and ulna can be considered moderate discriminators for determining sex in a South African group. However, it is advised that whenever possible these formulae are used in conjunction with visual methods to determine sex from skeletal remains. Copyright 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Barrier, ILO 2007, Sex determination from the bones of the forearm in a modern South African sample, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-08052008-090115 / > E961/ag / Dissertation (MSc)--University of Pretoria, 2008. / Anatomy / unrestricted