Sharp upper estimates for the first eigenvalue of a Jacobi type operator

Our purpose in this article is to obtain sharp upper estimates for the first positive eigenvalue of a Jacobi type operator, which is a suitable extension of the linearized operators of the higher order mean curvatures of a closed hypersurface immersed either in the Euclidean space or in the Euclidean sphere.Brazilian National Research Council (CNPq): grant 303977/2015-9 y grant 308757/2015-7.peerReviewe

Sharp upper estimates for the first eigenvalue of a Jacobi type operator

Our purpose in this article is to obtain sharp upper estimates for the first positive eigenvalue of a Jacobi type operator, which is a suitable extension of the linearized operators of the higher order mean curvatures of a closed hypersurface immersed either in the Euclidean space or in the Euclidean sphere.Brazilian National Research Council (CNPq): grant 303977/2015-9 y grant 308757/2015-7.peerReviewe

Significance Of Assessment Experiences During Initial Teacher Training In Physical Education

This study investigates how students in the final semester of their teacher training program (licensure) at the Center of Physical Education and Sports (CEFD), Espírito Santo Federal University, Brazil, (re)interpret their assessment experiences, an integral component of their teacher training. It employs the narrative as a theoretical and methodological perspective, and it utilizes student portfolios, as well as focus groups and semi-structured individual interviews as inputs for data generation. Ten students in their eighth, or final, semester participated in this study. These were the total respondents to a "call for volunteers" among the 2014 graduating class. The results suggest that the students believe the assessment processes of their teaching practices in physical education are disjointed. They feel that the disciplines that allow them to review their own performance during teacher training are more efficient and play a stronger role in their education.221627

Habitat specialization and phylogenetic structure of tree species in a coastal Brazilian white-sand forest

Aims The coastal Brazilian rainforest on white-sand (restinga) ranks among the most fragmented forest types in the tropics, owing to both the patchy distribution of sandy soils and widespread coastal development activities. Here we study the environmental and evolutionary determinants of a forest tree assemblage at a single restinga forest in Southeastern Brazil. We also explore the ability of competing hypotheses to explain the maintenance of species diversity in this forest type, which includes contrasting extremes of edaphic conditions associated with flooding stress. Methods The study was conducted in a white-sand forest permanent plot of 10.24 ha on the coastal plain of Southeastern Brazil. This plot was divided into 256 quadrats of 20×20 m, which were classified into two main edaphic habitats (flooded and drained). Trees with a diameter ≥1cm at breast height were identified. We assembled DNA sequence data for each of the 116 morphospecies recognized using two chloroplast markers (rbcL and matK). A phylogenetic tree was obtained using the maximum likelihood method, and a phylogenetic distance matrix was produced from an ultrametric tree. We analyzed similarity in floristic composition and structure between habitats and related them to cross-plot distances using permutation procedures. Null model torus shift simulations were performed to obtain a statistical significance level for habitat association for each species. The phylogenetic structure for the two habitats and for each 20×20 m quadrat was calculated using the mean phylogenetic distance weighted by species abundance and checked for significance using the standardized effect size generated by 5000 randomizations of phylogenetic tip labels. Important Findings Our results indicate that partitioning among edaphic habitats is important for explaining species distributions and coexistence in restinga forests. Species distributions within the plot were found to be non-random: there was greater floristic similarity within than between habitats, and >40% of the more abundant species were positively or negatively associated with at least one habitat. Patterns of habitat association were not independent of phylogenetic relatedness: the community was overdispersed with respect to space and habitat type. Closely related species tended to occur in different habitats, while neighboring trees tended to belong to more distantly related species. We conclude that habitat specialization is important for the coexistence of species in restinga forests and that habitat heterogeneity is therefore an essential factor in explaining the maintenance of diversity of this unique but fragile and threatened type of forest. © 2014 The Author