Influence of host diet and phylogeny on parasite sharing by fish in a diverse tropical floodplain.

The patterns of parasite sharing among hosts have important implications for ecosystem structure and functioning, and are influenced by several ecological and evolutionary factors associated with both hosts and parasites. Here we evaluated the influence of fish diet and phylogenetic relatedness on the pattern of infection by parasites with contrasting life history strategies in a freshwater ecosystem of key ecological importance in South America. The studied network of interactions included 52 fish species, which consumed 58 food types and were infected with 303 parasite taxa. Our results show that both diet and evolutionary history of hosts significantly explained parasite sharing; phylogenetically close fish species and/or species sharing food types tend to share more parasites. However, the effect of diet was observed only for endoparasites in contrast to ectoparasites. These results are consistent with the different life history strategies and selective pressures imposed on these groups: endoparasites are in general acquired via ingestion by their intermediate hosts, whereas ectoparasites actively seek and attach to the gills, body surface or nostrils of its sole host, thus not depending directly on its feeding habits.

Catch-per-unit-effort: which estimator is best?

In this paper we examine the accuracy and precision of three indices of catch-per-unit-effort (CPUE). We carried out simulations, generating catch data according to six probability distributions (normal, Poisson, lognormal, gamma, delta and negative binomial), three variance structures (constant, proportional to effort and proportional to the squared effort) and their magnitudes (tail weight). The Jackknife approach of the index is recommended, whenever catch is proportional to effort or even under small deviations from proportionality assumption, when a ratio estimator is to be applied and little is known about the underlying behaviour of variables, as is the case for most fishery studies.

Catch-per-unit-effort: which estimator is best? / Captura por unidade de esforço: qual estimador é melhor?

In this paper we examine the accuracy and precision of three indices of catch-per-unit-effort (CPUE). We carried out simulations, generating catch data according to six probability distributions (normal, Poisson, lognormal, gamma, delta and negative binomial), three variance structures (constant, proportional to effort and proportional to the squared effort) and their magnitudes (tail weight). The Jackknife approach of the index is recommended, whenever catch is proportional to effort or even under small deviations from proportionality assumption, when a ratio estimator is to be applied and little is known about the underlying behaviour of variables, as is the case for most fishery studies.

Neste trabalho, examinamos a acurácia e precisão de três índices de captura por unidade de esforço (CPUE). Foram feitas simulações, nas quais foram gerados dados de captura de acordo com seis distribuições de probabilidade (normal, Poisson, lognormal, gama, delta e binomial negativa), três estruturas de variância (constante, proporcional ao esforço e proporcional ao quadrado do esforço), e magnitudes (tail weight). É recomendado o uso do método Jackknife para os índices, sempre que a captura for proporcional ao esforço ou até em casos de pequenos desvios do pressuposto de proporcionalidade, quando se deseja utilizar um estimador de razão e pouco é conhecido sobre o real comportamento das variáveis, como é o caso da maioria dos estudos de pesca.

Larval ecomorphology of 13 Libellulidae (Anisoptera, Odonata) of the Middle Rio Doce Valley, Minas Gerais, Brazil.

In the lakes of the Middle Rio Doce, Minas Gerais (MG), two groups of larval Libellulidae are distinguished by preferences of habitat use: one uses mainly aquatic macrophytes and the other uses the bottom substrate. The goal of this work was to verify if there is a morphological distinction between the two groups of species. Thirteen body measures were taken from the larvae and analyzed. No difference was found between the two groups of species regarding the body size, but shape differences were observed for two morphological variables. The species that use mainly macrophytes tend to have larger relative measures of the labium and smaller measures of the abdomen width. Advantages in resource obtainment and in vulnerability to predation are probably the explanations for the morphological divergence among these larval groups.

Larval ecomorphology of 13 Libellulidae (Anisoptera, Odonata) of the Middle Rio Doce Valley, Minas Gerais, Brazil

In the lakes of the Middle Rio Doce, Minas Gerais (MG), two groups of larval Libellulidae are distinguished by preferences of habitat use: one uses mainly aquatic macrophytes and the other uses the bottom substrate. The goal of this work was to verify if there is a morphological distinction between the two groups of species. Thirteen body measures were taken from the larvae and analyzed. No difference was found between the two groups of species regarding the body size, but shape differences were observed for two morphological variables. The species that use mainly macrophytes tend to have larger relative measures of the labium and smaller measures of the abdomen width. Advantages in resource obtainment and in vulnerability to predation are probably the explanations for the morphological divergence among these larval groups.

Nos lagos do Médio Rio Doce (MG), dois grupos de larvas de Libellulidae apresentam diferenças no uso do habitat: um utiliza preferencialmente macrófitas aquáticas e o outro utiliza a superfície do fundo. O objetivo deste trabalho foi verificar se existe uma distinção morfológica entre estes dois grupos. Treze medidas morfológicas foram tiradas das larvas e analisadas. Nenhuma diferença, com relação ao tamanho corporal, foi encontrada entre os dois grupos, embora diferenças de forma tenham sido observadas com relação a duas variáveis morfológicas. As espécies que usam principalmente macrófitas tendem a possuir maiores medidas relativas do lábio e menores medidas da largura do abdome, o oposto ocorrendo com as larvas habitantes do fundo. Vantagens na captura de presas e na vulnerabilidade à predação são provavelmente as explicações para a divergência morfológica observada entre os dois grupos de larvas.

Shape of attractors for three-dimensional dissipative dynamical systems

We introduce a method to bound attractors of dissipative dynamical systems in phase and parameter spaces. The method is based on the determination of families of transversal surfaces (surfaces crossed by the flow in only one direction). This technique yields very restrictive geometric bounds in phase space for the attractors. It also gives ranges of parameters of the system for which no chaotic behavior is possible. We illustrate our method on different three-dimensional dissipative systems.

A statistical analysis of sequences of cardiac interbeat intervals does not support the chaos hypothesis.

Series of cardiac interbeat intervals were recorded in 34 mice and described using an original technique. The different intervals were divided into six classes according to their lengths. The different successions of pairs of intervals were counted with the help of a software programme devoted to lexical analysis. Most of the mice showed a very similar pattern of repeated sequences of interbeat intervals, statistically different from a random distribution. One-, two- or three-dimensional chaotic discrete maps were used to generate series that were then analyzed in the same way. They failed to give a distribution pattern of repeated sequences similar to the biological ones. On the contrary, series generated using a random component, and limited in amplitude by a feed-back correction occurring when the intervals reached a lower or an upper threshold, gave distributions of values very similar to biological ones. Moreover, the natural diversity observed between mice was easily reproduced by fluctuation of these different parameters. It is suggested that a very simple process, not completely deterministic, could better explain interbeat interval regulation in normal mice than did chaotic phenomena, which need complex biological processes.

Health conditions in Argentina: facing the twenty-first century.

This paper describes the state of health in Argentina. As in other countries in the Latin American region, the public sector and the role of the state in Argentina are in the midst of structural transformation. Public policy has been formulated with the aim of improving economic efficiency in the long term, often at the cost of basic services, such as health, education and safety. Provision of health care services to a population characterized by high levels of poverty and unemployment, which is also rapidly growing and ageing, needs to be addressed when major policies are decided. Otherwise, a large group of inhabitants in Argentina will not be able to reach the universally proposed minimum levels of health by the year 2000.

Epidemic of cholera among the aborigines of northern Argentina.

In February 1992, an epidemic of cholera began in Argentina. The first known case appeared in an aborigine population living by the Pilcomayo river on the Bolivian border. By the end of that year, 551 cases and 15 deaths were reported to the health authorities. Epidemiological analysis helped identify the pattern of transmission of the disease in this region of South America. Polluted watercourses and little pools, formed after the rainy season, were identified as the single source of infection for subsequent cases. Then, the epidemic adopted a person-to-person pattern of transmission and was propagated over a long course with weekly occurrence. Anthropological, cultural, and other factors that contributed to the origin and spread of cholera in northern Argentina are described in this study.

Sistema de información perinatal: Historia clínica perinatal base / Perinatal onformation system: Perinatal clinical history bases

A pesar de que la Historia Clínica es una pieza fundamental para un sistema de información adecuado y para un mejor ardenamiento de los servicios de salud, son notorias las deficiencias de que ésta adolece en la mayoría de los países de Latinoamérica. Como respuesta a ese problema, a inicios de la década de los ï70, el Centro Latinoamericano de Perinatología y Desarrollo Humano (CLAP) con sede en Montevideo, propuso un modelo de Historia Clínica Perinatal (HCPB) adoptado luego por varios países del Continente. Despues de dos años de trabajo, el equipo técnico del CLAP elaboró el Sistema Informático Perinatal. En esta tarea intervinieron obstetras, neonatólogos, sanitaristas, enfermeras, ingenieros de sistemas, bioestadístas y otros profesionales