Crossovers from parity conserving to directed percolation universality

The crossover behavior of various models exhibiting phase transition to absorbing phase with parity conserving class has been investigated by numerical simulations and cluster mean-field method. In case of models exhibiting Z_2 symmetric absorbing phases (the NEKIMCA and Grassberger's A stochastic cellular automaton) the introduction of an external symmetry breaking field causes a crossover to kink parity conserving models characterized by dynamical scaling of the directed percolation (DP) and the crossover exponent: 1/\phi ~ 0.53(2). In case an even offspringed branching and annihilating random walk model (dual to NEKIMCA) the introduction of spontaneous particle decay destroys the parity conservation and results in a crossover to the DP class characterized by the crossover exponent: 1/\phi\simeq 0.205(5). The two different kinds of crossover operators can't be mapped onto each other and the resulting models show a diversity within the DP universality class in one dimension. These 'sub-classes' differ in cluster scaling exponents.Comment: 6 pages, 6 figures, accepted version in PR

Extreme Events Decision Making in Transport Networks: A Holistic Approach Using Emergency Scenarios and Decision Making Theory

This paper proposes a novel method to analyse decision-making during extreme events. The method is based on Decision-making Theory and aims at understanding how emergency managers make decisions during disasters. A data collection framework and an analysis method were conceptualized to capture participant’s behaviour, perception and understanding throughout a game-board simulation exercise, which emulates an earthquake disaster scenario affecting transport systems. The method evaluates the participant’s actions in order to identify decision-making patterns, strengths and weaknesses. A set of case studies has shown two typical patterns, namely: a) Support immediate rescue; b) Support lifelines recovery. Good decision-making practices regard to objective-oriented decision making, understanding of conflicting priorities and appropriate resource management. Weaknesses are associated with comprehending relationships between community/environment and projecting future scenarios. Overall, the case study’s results demonstrate the efficiency and robustness of the proposed method to analyse decision making during disasters

Surface Effects on the Mechanical Elongation of AuCu Nanowires: De-alloying and the Formation of Mixed Suspended Atomic Chains

We report here an atomistic study of the mechanical deformation of AuxCu(1-x) atomic-size wires (NWs) by means of high resolution transmission electron microscopy (HRTEM) experiments. Molecular dynamics simulations were also carried out in order to obtain deeper insights on the dynamical properties of stretched NWs. The mechanical properties are significantly dependent on the chemical composition that evolves in time at the junction; some structures exhibit a remarkable de-alloying behavior. Also, our results represent the first experimental realization of mixed linear atomic chains (LACs) among transition and noble metals; in particular, surface energies induce chemical gradients on NW surfaces that can be exploited to control the relative LAC compositions (different number of gold and copper atoms). The implications of these results for nanocatalysis and spin transport of one-atom-thick metal wires are addressed.Comment: Accepted to Journal of Applied Physics (JAP

Efeito de diferentes substratos e sombreamento na distribuição de biomassa em mudas de Mororó (Bauhinia cheilantha (Bong.) Steud).

Este trabalho foi desenvolvido na Embrapa Semi-¡rido, Petrolina, PE e na Universidade do Estado da Bahia (UNEB), Juazeiro, BA, com o objetivo de avaliar a influência de diferentes substratos e nÌveis de sombreamentos na distribuição de biomassa de mudas de mororó

Comportamento fisiológico de sementes de Quixabeira (Sideroxylon obtusifolium Roem & Schult., Sapotaceae) submetidas a diferentes temperaturas de germinação.

Devido à degradação ambiental, a quixabeira (Sideroxylon obtusifolium (Roem & Schult.) é mais uma espécie ameaçada de extinção, sendo a mesma de grande importância pelas suas propriedades medicinal e madeireira. A fisiologia das sementes de quixabeira é pouco conhecida, bem como os fatores ambientais que influenciam na germinação das mesmas. O experimento foi desenvolvido na Embrapa Semi-Árido, Petrolina – PE., com o objetivo de gerar informações sobre o comportamento germinativo das sementes de quixabeira, submetidas a diferentes temperaturas

Alterações bioquímicas durante a embebição de sementes de baraúna (Schinopsis brasiliensis Engl.).

O objetivo deste trabalho foi obter a curva de embebição e avaliar as alterações bioquímicas que ocorrem nas sementes de baraúna durante a germinação