Seasonal variation of some limnological factors of lagoa do Guarana : a varzea lake of the High Rio Parana, state of Mato Grosso do Sul, Brazil

Le lac de Guarana présente de fortes variations saisonnières des conditions physico-chimiques du milieu. Celles-ci sont attribuées à deux causes principales : d'une part, le régime hydrologique du Parana qui provoque des modifications de niveau dans le lac et l'inondation de la varzea et, d'autre part, les pluies qui augmentent les apports de carbone organique (composés humiques) et des nutriments par les petits affluents tributaires. (Résumé d'auteur

On certain homological invariant and its relation with Poincaré duality pairs

Let G be a group, S = {Sᵢ, i ∊ I} a non empty family of (not necessarily distinct) subgroups of infinite index in G and M a Z₂G-module. In [4] the authors defined a homological invariant E*(G, S,M), which is “dual” to the cohomological invariant E(G, S,M), defined in [1]. In this paper we present a more general treatment of the invariant E*(G, S,M) obtaining results and properties, under a homological point of view, which are dual to those obtained by Andrade and Fanti with the invariant E(G, S,M). We analyze, through the invariant E*(G, S,M), properties about groups that satisfy certain finiteness conditions such as Poincaré duality for groups and pairs

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

Dynamical Chern-Simons modified gravity, Godel Universe and variable cosmological constant

We study the condition for the consistency of the G\"{o}del metric with the dynamical Chern-Simons modified gravity. It turns out to be that this compatibility can be achieved only if the cosmological constant is variable in the space.Comment: 8 pages, references adde

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

The effect of Zr and Sn additions on the microstructure of Ti-Nb-Fe gum metals with high elastic admissible strain

An open challenge on structural biomaterials is to obtain low-cost Ti-alloys with high elastic admissible strength (the ratio of yield strength to modulus). To reach this goal, we designed and characterized three quaternary alloys from the Ti-Nb-Fe system with additions of Zr and Sn. The samples were solution-treated and tested under two conditions: water-quenched and aged at 450 °C. Microstructures were analyzed with aid of scanning and transmission electron microscopy. Tensile tests performed at room-temperature confirmed a remarkable yield strength of 1271 MPa with an elastic modulus close to 90 GPa among aged Ti-19Nb-2.5Fe-6Sn (wt%) samples. Solution-treated Ti-19Nb-2.5Fe-10Zr samples presented a good combination of yield-strength and elastic modulus (1027 MPa and 69 GPa, respectively), displaying an elastic admissible strength close to 1.5. Although Zr and Sn are equally distributed between matrix and precipitates, the diffusion of Nb and Fe seem to be inhibited by the presence of Sn. As a result, Sn allows higher yield-strengths and more refined secondary α-phase, while Zr has a stronger effect on reducing the elastic modulus. In the end, a materials selection chart is presented to help designers to select materials for orthopedic implants considering the elastic admissible strain and cost as major guidelines16011861195CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão tem2014/24449-0; 2016/22714-3; 2016/24693-3Funding: This work was supported by FAPESP (São Paulo State Research Foundation, grants numbers 2014/24449-0, 2016/22714-3 and 2016/24693-3) and CNPq (National Council for Scientific and Technological Development). The authors gratefully acknowledge Prof. Hamish Fraser for the use of experimental facilities at the Center for Electron Microscopy and Analysis (CEMAS), at the Ohio State University, USA, and thank CBMM Co. for the Nb supply. The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. Data will be made available upon reques

Optical Absorption Measurements In A New Composite Material By Combined Photoacoustic And Beam Transmission Techniques

The absorption coefficient of a highly absorbing (β>105 cm-1) new composite produced in our laboratory, namely manganese dioxide surface-impregnated polyethylene (MnO2-PE) film, has been measured in the visible range. We have employed a combination of concurrently taken photoacoustic and beam transmission data. This combination proved to be an effective means for the optical evaluation of highly absorptive samples which dispenses with the need for prior knowledge of the sample reflectivity. Theoretical interpretation of MnO2-PE absorption profile, with due account of the processes underlining the photoacoustic signal generation, reveals a semiconductor behavior with an estimated effective gap wavelength of 8050 Å. Technical implications of the availability of these highly absorptive flexible films are briefly considered.5794431443