Probabilistic structure of an annual extreme rainfall series of a coastal area of the State of São Paulo, Brazil

This study aimed to describe the probabilistic structure of the annual series of extreme daily rainfall (Preabs), available from the weather station of Ubatuba, State of São Paulo, Brazil (1935-2009), by using the general distribution of extreme value (GEV). The autocorrelation function, the Mann-Kendall test, and the wavelet analysis were used in order to evaluate the presence of serial correlations, trends, and periodical components. Considering the results obtained using these three statistical methods, it was possible to assume the hypothesis that this temporal series is free from persistence, trends, and periodicals components. Based on quantitative and qualitative adhesion tests, it was found that the GEV may be used in order to quantify the probabilities of the Preabs data. The best results of GEV were obtained when the parameters of this function were estimated using the method of maximum likelihood. The method of L-moments has also shown satisfactory results.

Be-Fe coupled method for the analysis of 3D elastodynamic problems in the time domain

By coupling the Boundary Element Method (BEM) and the Finite Element Method (FEM) an algorithm that combines the advantages of both numerical processes is developed. The main aim of the work concerns the time domain analysis of general three-dimensional wave propagation problems in elastic media. In addition, mathematical and numerical aspects of the related BE-, FE- and BE/FE-formulations are discussed. The coupling algorithm allows investigations of elastodynamic problems with a BE- and a FE-subdomain. In order to observe the performance of the coupling algorithm two problems are solved and their results compared to other numerical solutions.

Variability and Genetic Structure in Populations of Arrabidaea bilabiata (Sprague) Sandwith in the Amazonas State

Weeds in pastures can intoxicate animals, and Arrabidaea bilabiata is the most important species for herbivores in floodplain areas in the Amazon Basin. Genetic diversity studies in natural populations may contribute to the better understanding of the range of toxicity and the genetic variability organization in this species. The objective of this study was to assess the variability and genetic structure in six populations of A. bilabiata sampled in floodplain areas in three municipalities of the Amazonas State, from the AFLP markers analysis. AFLP markers were efficient to characterize the genetic variability of the 65 individuals analyzed. From four combinations of oligonucleotides, a total of 309 AFLP fragments was obtained, where 304 (98.38%) were polymorphic. By the dendrogram and Bayesian cluster analysis, there was a formation of two isolated groups, the first one comprising individuals from Autazes municipality and the second one comprising individuals from Itacoatiara and Parintins. However, depending on the method to define the most probable cluster number, there was a separation of the six populations, according to their geographical origin. Mantel test confirmed that geographically closer populations are more akin, although low gene flow (0.538) is observed among the sampled populations. The molecular analysis of variance found that 49.29% of the genetic variability are among individuals inside populations and 50.71% among the populations analyzed. The results indicate the possibility that isolated A. bilabiata populations contain plants with different toxicity levels and suggest a strong adaptability of the species.

Spatial variation in the structure and floristic composition of "restinga" vegetation in southeastern Brazil

We examined large-scale spatial variation of structural parameters and floristic composition in open Clusia scrub, a vegetation type of the Brazilian "restingas" (sandy coastal plain vegetation). This vegetation is organized in islands separated by sandy stretches with sparse herbaceous vegetation. We located 12 sample areas on three consecutive beach ridges, lying parallel to the coastline and at different distances from the ocean, in close proximity to two lagoons (Cabiúnas and Comprida). Each sample area was divided into three strips. We used the line intercept method to sample all woody plants ³ 50 cm tall. We used nested ANOVA to verify structural variation between different sampling scales. TWINSPAN analysis was performed to examine the variation in floristic composition between areas. The overall diversity index was 3.07. Six species are repeatedly dominant throughout the entire sampling area. There was homogeneity in relation to diversity and species richness between beach ridges but not within beach ridges. Floristic composition and structural parameters did not vary in relation to distance from the sea but floristic composition did vary as a function of proximity to Cabiúnas or Comprida lagoon. Differences in plant cover between sample areas may be related to the paleoformation of this sandy coastal plain.

Alternative oxidase in the branched mitochondrial respiratory network: an overview on structure, function, regulation, and role

Plants and some other organisms including protists possess a complex branched respiratory network in their mitochondria. Some pathways of this network are not energy-conserving and allow sites of energy conservation to be bypassed, leading to a decrease of the energy yield in the cells. It is a challenge to understand the regulation of the partitioning of electrons between the various energy-dissipating and -conserving pathways. This review is focused on the oxidase side of the respiratory chain that presents a cyanide-resistant energy-dissipating alternative oxidase (AOX) besides the cytochrome pathway. The known structural properties of AOX are described including transmembrane topology, dimerization, and active sites. Regulation of the alternative oxidase activity is presented in detail because of its complexity. The alternative oxidase activity is dependent on substrate availability: total ubiquinone concentration and its redox state in the membrane and O2 concentration in the cell. The alternative oxidase activity can be long-term regulated (gene expression) or short-term (post-translational modification, allosteric activation) regulated. Electron distribution (partitioning) between the alternative and cytochrome pathways during steady-state respiration is a crucial measurement to quantitatively analyze the effects of the various levels of regulation of the alternative oxidase. Three approaches are described with their specific domain of application and limitations: kinetic approach, oxygen isotope differential discrimination, and ADP/O method (thermokinetic approach). Lastly, the role of the alternative oxidase in non-thermogenic tissues is discussed in relation to the energy metabolism balance of the cell (supply in reducing equivalents/demand in energy and carbon) and with harmful reactive oxygen species formation.

Diagnosing dementia and normal aging: clinical relevance of brain ratios and cognitive performance in a Brazilian sample

The main objective of the present study was to evaluate the diagnostic value (clinical application) of brain measures and cognitive function. Alzheimer and multiinfarct patients (N = 30) and normal subjects over the age of 50 (N = 40) were submitted to a medical, neurological and cognitive investigation. The cognitive tests applied were Mini-Mental, word span, digit span, logical memory, spatial recognition span, Boston naming test, praxis, and calculation tests. The brain ratios calculated were the ventricle-brain, bifrontal, bicaudate, third ventricle, and suprasellar cistern measures. These data were obtained from a brain computer tomography scan, and the cutoff values from receiver operating characteristic curves. We analyzed the diagnostic parameters provided by these ratios and compared them to those obtained by cognitive evaluation. The sensitivity and specificity of cognitive tests were higher than brain measures, although dementia patients presented higher ratios, showing poorer cognitive performances than normal individuals. Normal controls over the age of 70 presented higher measures than younger groups, but similar cognitive performance. We found diffuse losses of tissue from the central nervous system related to distribution of cerebrospinal fluid in dementia patients. The likelihood of case identification by functional impairment was higher than when changes of the structure of the central nervous system were used. Cognitive evaluation still seems to be the best method to screen individuals from the community, especially for developing countries, where the cost of brain imaging precludes its use for screening and initial assessment of dementia.

Study of the comprehension of the scientific method by members of a university health research laboratory

In Brazil, scientific research is carried out mainly at universities, where professors coordinate research projects with the active participation of undergraduate and graduate students. However, there is no formal program for the teaching/learning of the scientific method. The objective of the present study was to evaluate the comprehension of the scientific method by students of health sciences who participate in scientific projects in an academic research laboratory. An observational descriptive cross-sectional study was conducted using Edgar Morin complexity as theoretical reference. In a semi-structured interview, students were asked to solve an abstract logical puzzle - TanGram. The collected data were analyzed using the hermeneutic-dialectic analysis method proposed by Minayo and discussed in terms of the theoretical reference of complexity. The students’ concept of the scientific method is limited to participation in projects, stressing the execution of practical procedures as opposed to scientific thinking. The solving of the TanGram puzzle revealed that the students had difficulties in understanding questions and activities focused on subjects and their processes. Objective answers, even when dealing with personal issues, were also reflected on the students’ opinions about the characteristics of a successful researcher. Students’ difficulties concerning these issues may affect their scientific performance and result in poorly designed experiments. This is a preliminary study that should be extended to other centers of scientific research.

Ultrasound method applied to characterize healthy femoral diaphysis of Wistar rats in vivo

A simple experimental protocol applying a quantitative ultrasound (QUS) pulse-echo technique was used to measure the acoustic parameters of healthy femoral diaphyses of Wistar rats in vivo. Five quantitative parameters [apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), time slope of apparent backscatter (TSAB), integrated reflection coefficient (IRC), and frequency slope of integrated reflection (FSIR)] were calculated using the echoes from cortical and trabecular bone in the femurs of 14 Wistar rats. Signal acquisition was performed three times in each rat, with the ultrasound signal acquired along the femur's central region from three positions 1 mm apart from each other. The parameters estimated for the three positions were averaged to represent the femur diaphysis. The results showed that AIB, FSAB, TSAB, and IRC values were statistically similar, but the FSIR values from Experiments 1 and 3 were different. Furthermore, Pearson's correlation coefficient showed, in general, strong correlations among the parameters. The proposed protocol and calculated parameters demonstrated the potential to characterize the femur diaphysis of rats in vivo. The results are relevant because rats have a bone structure very similar to humans, and thus are an important step toward preclinical trials and subsequent application of QUS in humans.

Effect of modified clays on the structure and functional properties of biofilms produced with zein

The purpose of this study was to evaluate changes in the structure and some functional properties of biofilms added with modified clays (Cloisite® 15A and Cloisite® 30B) prepared by the casting method. The analysis of the microstructure of the films, scanning electron microscopy (SEM), Optical microscopy (MO), and Infrared Spectroscopy (FTIR) indicated that the addition of clay in the films resulted in the formation of a heterogeneous microstructure, microcomposite or tactoid. Due to the formation of a microcomposite structure, functional properties of the films added with both clays such as opacity, solubility, and permeability to water vapor (PVA), were not better than those of the control film. Thus, it was concluded that although it is possible to produce a film added with modified clays using the casting method, it was not possible to obtain intercalation or exfoliation in a nanocomposite, which would result in improved functional properties.