Experimental Realization of the Fuse Model of Crack Formation

In this work, we present an experimental investigation of the fuse model. Our main goal was to study the influence of the disorder on the fracture process. The experimental apparatus used consisted of an $L\times L$ square lattice with fuses placed on each bond of the lattice. Two types of materials were used as fuses: copper and steel wool wires. The lattice composed only by copper wires varied from a weakly disordered system to a strongly disordered one. The lattice formed only by steel wool wires corresponded to a strongly disordered one. The experimental procedure consisted of applying a potential difference V to the lattice and measuring the respective current I. The characteristic function $I(V)$ obtained was investigated in order to find the scaling law dependence of the voltage and the current on the system size $L$ when the disorder was changed. Our results show that the scaling laws are only verified for the disordered regime.Comment: 4 pages, 8 figures.ep

Vegetable Garden at School

This project began in 2018/2019 due to the interests shown by three classes of the 5th year. Through a brainstorm, we realized that the concern about the lack of green spaces was common to several students of the school. Thus, the vegetable garden would make the school greener and more open to the community. The space for construction was chosen and partnerships were created with the department of environmental management and transport of Odivelas (CMO), and the school parents association. We have privileged collaborative and interdisciplinary work to streamline various activities throughout the school year. The study ofsoil, seeds, autochthonous plants and pollinating insects was done with the help of class teachers and librarian teachers. The days of the native forest and the tree were celebrated with the planting of trees and the holding of a plant fair. At school and throughout the year students disseminated their project through informative posters, school radio and the school's website

Situação atual e perspectivas do ensino, capacitação e pesquisa agroflorestal no Brasil: uma abordagem com ênfase na região amazônica.

Trabalhos apresentados no Congresso Brasileiro de Sistemas Agroflorestais, 4., 2002, Ilhéus

Ensino e capacitação agroflorestal no Brasil: uma abordagem com enfase na região Amazônica.

Cópia de trabalho editado em CD-ROM

Stochastic Quantization of Topological Field Theory: Generalized Langevin Equation with Memory Kernel

We use the method of stochastic quantization in a topological field theory defined in an Euclidean space, assuming a Langevin equation with a memory kernel. We show that our procedure for the Abelian Chern-Simons theory converges regardless of the nature of the Chern-Simons coefficient

The importance of the mixed phase in hybrid stars built with the Nambu-Jona-Lasinio model

We investigate the structure of hybrid stars based on two different constructions: one is based on the Gibbs condition for phase coexistence and considers the existence of a mixed phase (MP), and the other is based on the Maxwell construction and no mixed phase is obtained. The hadron phase is described by the non-linear Walecka model (NLW) and the quark phase by the Nambu-Jona-Lasinio model (NJL). We conclude that the masses and radii obtained are model dependent but not significantly different for both constructions.Comment: 8 pages, 7 figures, 3 table

Critical and Tricritical Points for the Massless 2d Gross-Neveu Model Beyond Large N

Using optimized perturbation theory, we evaluate the effective potential for the massless two dimensional Gross-Neveu model at finite temperature and density containing corrections beyond the leading large-N contribution. For large-N, our results exactly reproduce the well known 1/N leading order results for the critical temperature, chemical potential and tricritical points. For finite N, our critical values are smaller than the ones predicted by the large-N approximation and seem to observe Landau's theorem for phase transitions in one space dimension. New analytical results are presented for the tricritical points that include 1/N corrections. The easiness with which the calculations and renormalization are carried out allied to the seemingly convergent optimized results displayed, in this particular application, show the robustness of this method and allows us to obtain neat analytical expressions for the critical as well as tricritical values beyond the results currently known.Comment: 29 pages, 14 figure