Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2016-10-20T18:25:56Z No. of bitstreams: 1 2016 - Cristina Fernandes do Amarante.pdf: 776756 bytes, checksum: 758e9e88a96110176bd0dff013f8c6ac (MD5) / Made available in DSpace on 2016-10-20T18:25:56Z (GMT). No. of bitstreams: 1 2016 - Cristina Fernandes do Amarante.pdf: 776756 bytes, checksum: 758e9e88a96110176bd0dff013f8c6ac (MD5) Previous issue date: 2016-03-03 / CNPq / This study aimed to assess the factors involved in the determination of ecological events, including parasite aggregation, abundance, and dominance, via multivariate analysis using fish as a biological model. For this purpose, we used a database consisting of 3,746 fish specimens collected on the coast of Rio de Janeiro and from the Guandu river and evaluated their characteristics, habits, and associated parasites. Parasites were grouped into seven higher taxa: Nematoda, Monogenea, Cestoda, Trematoda, Acanthocephala, Hirudinea, and Crustacea. Aggregation was calculated using the dispersion index; abundance was determined by calculating the total number of parasites; and dominance was calculated using the Berger-Parker index. Data normality was tested using the Shapiro-Wilk test; group comparisons, when necessary, were performed using the Wilcoxon test or the Kruskal-Wallis test. Adjustments were made in the linear regression models for parasite aggregation in each parasite taxon evaluated and in the mixed-effect models to evaluate abundance and dominance using Poisson and Gaussian distributions, respectively. The factors inherent to the hosts, including sex, size, habitats, formation of schools, eating habits, and aquatic environments, were tested as potential explanatory variables of these ecological events. In addition, the parasite development stage and parasite taxa were included as explanatory variables in the analysis of the determinants of aggregation and dominance, respectively. In the mixed-effects model, the ecological events were considered an outcome variable, and fish species were considered a random variable. Regression coefficients were calculated in the study of aggregation, and parasite dominance and prevalence rate were estimated in the study of abundance. Significance was determined using confidence intervals (CI) and the Wald test. All calculations were performed using R software with a confidence interval of 95%. Statistically significant associations between levels of parasite aggregation and explanatory variables (factors inherent to the host and the percentage of larvae) varied according to the parasite taxon. The coefficient of determination was lower than 60% in all of the adjusted models, indicating that factors other than those analyzed may be associated with the level of parasite aggregation. Parasite abundance was significantly associated with sex, formation of schools, habitats, and host length, which were considered risk factors. The numerical dominance of parasites was significantly associated with host length and the taxa Nematoda, Trematoda, Monogenea, Hirudinea, and Crustacea. In addition, our results indicate that the mixed-effects model was more parsimonious compared with the classical model, underscoring the importance of choosing a statistical model that takes into consideration the nature of the data to avoid spurious results, especially when autocorrelations data were not considered. In general, our results point to the need for developing studies with more comprehensive databases and larger samples of parasite species, in which data on the life cycles of fish species and parasite taxa can be analyzed more thoroughly. / Este trabalho teve como objetivo avaliar fatores envolvidos na determina??o dos eventos ecol?gicos: agrega??o, a abund?ncia e a domin?ncia parasit?ria por meio de an?lises multivariadas, utilizando peixes como modelo biol?gico. Para tanto, foi utilizado um banco de dados composto por 3.746 esp?cimes de peixes, suas caracter?sticas e h?bitos e seus parasitos, provenientes do litoral do Rio de Janeiro e do Rio Guandu. Os parasitos foram agrupados em sete t?xons superiores: Nematoda, Monogenea, Cestoda, Trematoda, Acanthocephala, Hirud?nea e Crust?cea. A agrega??o foi calculada atrav?s do ?ndice de dispers?o; a abund?ncia pela quantidade total de parasitas computados; e a domin?ncia atrav?s do ?ndice de Berger Parker. A normalidade dos dados foi testada pelo teste de Shapiro Wilk e a compara??o de grupos, quando necess?ria, foi realizada pelo teste de Wilcoxon ou Kruskal-Wallis. Foram ajustados modelos de regress?o linear para a agrega??o parasit?ria para cada t?xon parasit?rio estudado e modelos de efeitos mistos para an?lise dos determinantes da abund?ncia e da domin?ncia, com distribui??o de Poisson e gaussiana, respectivamente. Os fatores inerentes aos hospedeiros tais como: sexo, tamanho, habitat, forma??o de cardumes, h?bitos alimentares e ambiente aqu?tico foram testados como poss?veis vari?veis explicativas desses eventos ecol?gicos. Al?m desses, na an?lise dos determinantes da agrega??o e domin?ncia foram inclu?dos os fatores est?dio de desenvolvimento do parasita e os t?xons parasit?rios como vari?veis explicativas, respectivamente. Os eventos ecol?gicos foram considerados vari?veis desfecho e nos modelos mistos a esp?cie de peixe como vari?vel aleat?ria. Foram calculados os coeficientes de regress?o nos estudos de agrega??o e domin?ncia parasit?ria e estimada a raz?o de preval?ncia no estudo de abund?ncia. A signific?ncia foi verificada por meio o intervalo de confian?a (IC) e do teste de Wald. Todos os c?lculos foram realizados utilizando o software R, com um IC de 95%. As associa??es estatisticamente significativas entre o n?vel de agrega??o parasit?ria e as vari?veis explicativas (fatores inerentes ao hospedeiro e propor??o de larvas) variaram conforme o t?xon parasit?rio. O coeficiente de determina??o foi inferior a 60%, em todos os modelos ajustados, indicando que outros, fatores al?m dos analisados, devam estar relacionados ao grau de agrega??o parasit?ria. A abund?ncia parasit?ria mostrou-se associada significativamente ?s vari?veis: sexo, forma??o de cardumes, habitat e comprimento do hospedeiro, que se comportaram como poss?veis fatores de risco. A domin?ncia num?rica de parasitos esteve associada significativamente ao comprimento do hospedeiro e aos t?xons Nematoda, Trematoda, Monogenea, Hirud?nea e Crust?cea. Os resultados mostraram que os modelos mistos foram mais parcimoniosos em rela??o aos modelos cl?ssicos, refor?ando a import?ncia da escolha de um modelo estat?stico mais adequado ? natureza dos dados, evitando-se resultados esp?rios, principalmente quando n?o se leva em conta a autocorrela??o dos dados..De um modo geral, os resultados deste estudo sinalizam para a necessidade de pesquisas com bancos de dados mais abrangentes e com amostras maiores de esp?cies de parasitos, nos quais as caracter?sticas do ciclo biol?gico das esp?cies de peixes e dos t?xons parasit?rios possam ser mais detalhados nas an?lises.

Made available in DSpace on 2014-12-17T14:57:49Z (GMT). No. of bitstreams: 1 JaniaraFA.pdf: 946913 bytes, checksum: 7a2683c43f2b9a59eaca617cf3e52563 (MD5) Previous issue date: 2008-11-13 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The production of roof tiles in the state of Rio Grande do Norte accounts for around 60% of the total of ceramic pieces produced. There is a need for investment to improve quality and productivity, thereby promoting technological innovations. Accordingly, the aim of this study is to determine the effect of kaolin, potassium feldspar and quartz in two standard formulations, as well as the effect of sintering temperature on the technological properties of linear firing shrinkage, water absorption and bending rupture stress, by fitting the statistical model and using multiple linear regression to assess the relationship between technological properties and independent variables. The raw materials were characterized using the following techniques: X-ray fluorescence (XRF), X-ray diffraction (XRF), rational analysis (RA), differential thermal analysis (DTA) and granulometric analysis (GA). The test specimens were compacted by uniaxial pressure (25 MPa), dried in a stove at 110 ?C for 24 hours and sinterized at 850 ?C, 950 ?C and 1050 ?C and held isothermal for 30 minutes. The results obtained indicate that the addition of kaolin to two standard formulations (M and R) promoted a reduction in water absorption values and an increase in bending rupture stress values. The sintering temperatures for group M that resulted in the lowest linear firing shrinkage and water absorption values were 850 ?C and 950 ?C, respectively, and the highest bending rupture stress values were reached at a temperature of 950 ?C. In the case of group R, the sintering temperature that obtained the lowest water absorption and linear firing shrinkage values was 850 ?C, and the highest bending rupture stress values were attained at a temperature of 1050 ?C. This work explains the statistical approach used to fit the model that describes the relationship between the technological properties and percentage of kaolin, quartz and feldspar, as well as the models that enable predictions, provided that the lower and upper limits of the percentage of clay minerals, flux and quartz used in this study are respected. Statistica 6 software was used and results were obtained by stepwise forward regression / A produ??o de telha no Estado do Rio Grande do Norte representa cerca de 60 % do total de pe?as cer?micas produzidas. Percebe-se a necessidade de investimento na melhoria da qualidade e da produtividade, promovendo assim inova??es tecnol?gicas. Neste contexto, o objetivo geral deste trabalho ? verificar o efeito da adi??o de caulim, feldspato pot?ssico e quartzo em duas formula??es padr?o, assim como o efeito da temperatura de sinteriza??o nas propriedades tecnol?gicas de retra??o linear de queima, absor??o de ?gua e tens?o de ruptura ? flex?o, atrav?s do ajuste do modelo estat?stico, sendo utilizada a regress?o linear m?ltipla para avaliar a rela??o entre as propriedades tecnol?gicas e as vari?veis independentes. As mat?rias-primas foram caracterizadas atrav?s das seguintes t?cnicas: fluoresc?ncia de raios X (FRX), difra??o de raios X (DRX), an?lise racional (AR), an?lise t?rmica diferencial (DTA) e an?lise granulom?trica (AG). Os corpos-de-prova foram compactados por prensagem uniaxial (25 MPa), e na sequ?ncia secos em estufa a 110 ?C por 24 horas, em seguida sinterizados a 850 ?C, 950 ?C e 1050 ?C, com isoterma de 30 minutos. Os resultadosobtidos indicaram que a adi??o de caulim, em duas formula??es padr?o (M e R) promoveu redu??o nos valores de absor??o de ?gua e aumento nos valores de tens?o de ruptura ? flex?o. As temperaturas de sinteriza??o para o grupo M que proporcionaram os menores valores para a retra??o linear de queima e absor??o de ?gua foram 850 ?C e 950 ?C, respectivamente, e os maiores valores para a tens?o de ruptura ? flex?o foram alcan?ados na temperatura de 950 ?C. No caso do grupo R a temperatura de sinteriza??o que proporcionou os menores valores para absor??o de ?gua e retra??o linear de queima, foi a de 850 ?C, e os maiores valores para a tens?o de ruptura ? flex?o foram atingidosna temperatura de 1050 ?C. Este trabalho descreve a abordagem estat?stica para ajustar o modelo de regress?o linear m?ltipla e apresenta o ajuste do modelo que descreve a rela??o entre as propriedades tecnol?gicas e a porcentagem de caulim, quartzo e feldspato, assim como os modelos que possibilitam a realiza??o de predi??es, desde que n?o sejam ultrapassados os limites inferiores e superiores da porcentagem de argilominerais, fundente e quartzo utilizados neste trabalho. Para isto utilizou-se o software Statistica vers?o 6, obtendo resultados atrav?s da regress?o stepwise forward