Studies on the biology of the gyrodactyloidea (monogenea)

PhDThis study has examined the interaction between the viviparous rnonogenean GyrodactYlus and sticklebacks. Six species of Gyrodactylus were collected from Gasterosteus aculeatus and Pungitius pungitius in Britain. Each was narrowly host specific, and was restricted to either the gills or the body surface of the fish. A difference in attachment mechanism was noted between gill parasites (e.g. G. rarus), in which the hamuli were more important, and skin parasites (e.g. G. gasterostei), which relied upon the marginal hooks .. The observed growth rate of G. gasterostei populations upon Gasterosteus aculeatus was considerably slower than the calculated potential rate. In the later stages of infestation the population declined, possibly as a result of an increase in the probability of the ~. parasites becoming detached. This may have been related to an observed increase in the number of goblet mucus cells in the skin of infected fish. Although detached parasites were able to reinfect other fish, infection more frequently resulted from transmission during host-host contact. The abundance of Gyrodactylus spp. in the river Ver, Herts., England, was found to be limited by the annual life cycle of the hosts, which restricted transmission between adults and fry to a short period in midsummer. A comparison was made with the biology of the related Gyrdicotylus gallieni, from the amphibian Xenonus laevis. This parasite, which has a suctorial attachment mechanism, inhabits the mouth of its host, entering this habitat via the nostrils. The slow population growth, and preponderance of older flukes in the population suggests that this parasite may be adapted for persistence in individual hosts. Q. gallieni has a wider host specificity than GyrodactYlus spp., and has been recorded from five species and sub-species of Xenopus. An oviparous monogenean, closely related to the viviparous genera, has been described from the catfish Farlowella amazonum. The origin and evolution of the gyrodactylids from a form similar to this parasite has been discusse

Modelos de pérdidas agregadas (LDA) y de la teoría del valor extremo para cuantificar el riesgo operativo teoría y aplicaciones

El aspecto más relevante desarrollado en el presente trabajo es implementar dos métodos para medir el riesgo operativo: El Valor en Riesgo (VaR) y uno de los modelos Picos sobre un umbral (POT) de la Teoría Básica del Valor Extremo (EVT). Primero se hace una introducción a lo que es el riesgo y riesgo operativo y un poco de contexto histórico de los dos métodos. Segundo se presentan las diferentes distribuciones de probabilidad para los eventos de riesgo (frecuencias y severidad) más usadas, se presenta la forma de estimar los parámetros y como es el generador de procesos para simularlas. Posteriormente se aclaran dos modelos para tratar valores extremos de la Teoría del Valor Extremo el Máximo por bloques y el Picos sobre un umbral (POT) con sus respectivas distribuciones más usadas: la Distribución Generalizada de Pareto y la Distribución de Valor Extremo Generalizada (en el Anexo A, B, y C se presenta también un resumen de las distribuciones: Familia Beta Transformada Familia Gamma Transformada y Distribuciones para grandes pérdidas). Se hace explicita la forma de calcular el VaR y Pérdidas Esperadas y la pérdidas inesperadas que nos permite reservar un capital para proteger una empresa del Riesgo Operativo.134 p.Contenido parcial: Riesgo y riesgo operativo -- Teoría y modelos de valores extremos -- Método de distribución de pérdida agregada (LDA) -- Aplicació

The R Journal (December 2015) 7(2): Complete Issue

Editorial, Bettina Grün Contributed Research Articles Fitting Conditional and Simultaneous Autoregressive Spatial Models in hglm, Moudud Alam, Lars Rönnegård, and Xia Shen VSURF: An R Package for Variable Selection Using Random Forests, Robin Genuer, Jean-Michel Poggi, and Christine Tuleau-Malot zoib: An R Package for Bayesian Inference for Beta Regression and Zero/One Inflated Beta Regression, Fang Liu, and Yunchuan Kong apc: An R Package for Age-Period-Cohort Analysis, Bent Nielsen QuantifQuantile: An R Package for Performing Quantile Regression Through Optimal Quantization, Isabelle Charlier, Davy Paindaveine, and Jérôme Saracco Numerical Evaluation of the Gauss Hypergeometric Function with the hypergeo Package, Robin K. S. Hankin SRCS: Statistical Ranking Color Scheme for Visualizing Parameterized Multiple Pairwise Comparisons with R, Pablo J. Villacorta and José A. Sáez An R Package for the Panel Approach Method for Program Evaluation: pampe, Ainhoa Vega-Bayo BSGS: Bayesian Sparse Group Selection, Kuo-Jung Lee and Ray-Bing Chen ClustVarLV: An R Package for the Clustering of Variables Around Latent Variables, Evelyne Vigneau, Mingkun Chen, and El Mostafa Qannari Working with Multilabel Datasets in R: The mldr Package, Francisco Charte and David Charte PracTools: Computations for Design of Finite Population Samples, Richard Valliant, Jill A. Dever, and Frauke Kreuter ALTopt: An R Package for Optimal Experimental Design of Accelerated Life Testing, Kangwon Seo and Rong Pan abctools: An R Package for Tuning Approximate Bayesian Computation Analyses, Matthew A. Nunes and Dennis Prangle mtk: A General-Purpose and Extensible R Environment for Uncertainty and Sensitivity Analyses of Numerical Experiments, Juhui Wang, Robert Faivre, Hervé Richard, and Hervé Monod treeClust: An R Package for Tree-Based Clustering Dissimilarities, Samuel E. Buttrey and Lyn R. Whitaker mmpp: A Package for Calculating Similarity and Distance Metrics for Simple and Marked Temporal Point Processes, Hideitsu Hino, Ken Takano, and Noboru Murata Open-Channel Computation with R, Michael C. Koohafkan and Bassam A. Younis Generalized Hermite Distribution Modelling with the R Package hermite, David Moriña, Manuel Higueras, Pedro Puig, and María Oliveira Code Profiling in R: A Review of Existing Methods and an Introduction to Package GUIProfiler, Angel Rubio and Fernando de Villar News and Notes The R Consortium and the R Foundation, Martyn Plummer Conference Report: useR! 2015, Torben Tvedebrink News from the Bioconductor Project, The Bioconductor Team Changes in R, The R Core Team Changes on CRAN, Kurt Hornik and Achim Zeilei