Optimization of hierarchical structures of information flow

The efficiency of a large hierarchical organisation is simulated on Barabasi-Albert networks, when each needed link leads to a loss of information. The optimum is found at a finite network size, corresponding to about five hierarchical layers, provided a cost for building the network is included in our optimization.Comment: Draft of 6 pages including all figure

Extensão universitária discente

Trabalho apresentado no II Congresso Nacional do PROJETO RONDON, realizado em Florianópolis, SC, no período de 23 a 25 de setembro de 2015 - Universidade Federal de Santa Catarina.Base do Ensino Superior, a extensão universitária, assim como ensino e pesquisa, além de fechar o ciclo do conhecimento científico, ainda estimula o voluntariado, desenvolvendo a sensibilidade no aluno, imprescindível para a sua evolução profissional. Na medida em que o mercado esta saturado de profissionais de notável saber acadêmico, mas completamente insensíveis no trato com as pessoas, incapazes de se colocar no lugar do outro. Tão importante quanto o conhecimento profissional é o conhecimento de si mesmo, da capacidade em relacionar-se com as pessoas, pois é exatamente na qualidade das relações entre as pessoas que se encontra a utilidade da profissão. Hodiernamente o mercado não deixa de considerar a razão do conhecimento profissional técnico e científico, mas paulatinamente vem reconhecendo a importância do autoconhecimento. O equilíbrio emocional nas relações pessoais tem sido o fator decisivo tanto nas contratações quanto nas promoções. E o campo fértil para o desenvolvimento da sensibilidade do acadêmico, é a extensão universitária, a exemplo do que significa o Projeto Rondon para o estudante do ensino superior, onde o aluno enxerga o Brasil com ele é, e não como deveria ser. O caminho para o Brasil que queremos começa na sua realidade. E essa realidade precisa ser conhecida na sua fonte, por aqueles que pretendem mudá-la, fazendo acontecer cidadania na vida das pessoas. Contudo, apesar das dificuldades de toda ordem, a posição das Instituições de Ensino Superior, em relação à extensão universitária vem passo a passo melhorando, ainda não é o ideal, mas é inegável a mudança de perfil dos alunos das IES. E o motivo dessa mudança é a política do Governo Federal de inclusão dos alunos dos setores de baixa renda. Essa ocupação oxigenou o pensamento acadêmico, levantando novos questionamentos sobre a função social dos cursos superiores na vida das comunidades carentes. O que é bom para o ensino e a pesquisa, e melhor ainda para a extensão universitária. Aglutinar as bases do ensino superior no Brasil, ainda é um desafio a ser superado por alunos e professores. A falta de investimentos significativos em extensão universitária é uma tentativa clara de colocar preço na educação, o que por óbvio é inadmissível. O conhecimento não tem limite, assim como também, não tem preço

Hermitian Dirac Hamiltonian in time dependent gravitational field

It is shown by a straightforward argument that the Hamiltonian generating the time evolution of the Dirac wave function in relativistic quantum mechanics is not hermitian with respect to the covariantly defined inner product whenever the background metric is time dependent. An alternative, hermitian, Hamiltonian is found and is shown to be directly related to the canonical field Hamiltonian used in quantum field theory.Comment: 9 pages, final version, to appear in Class. Quant. Gra

Finite-size effects in roughness distribution scaling

We study numerically finite-size corrections in scaling relations for roughness distributions of various interface growth models. The most common relation, which considers the average roughness $$as scaling factor, is not obeyed in the steady states of a group of ballistic-like models in 2+1 dimensions, even when very large system sizes are considered. On the other hand, good collapse of the same data is obtained with a scaling relation that involves the root mean square fluctuation of the roughness, which can be explained by finite-size effects on second moments of the scaling functions. We also obtain data collapse with an alternative scaling relation that accounts for the effect of the intrinsic width, which is a constant correction term previously proposed for the scaling of$$. This illustrates how finite-size corrections can be obtained from roughness distributions scaling. However, we discard the usual interpretation that the intrinsic width is a consequence of high surface steps by analyzing data of restricted solid-on-solid models with various maximal height differences between neighboring columns. We also observe that large finite-size corrections in the roughness distributions are usually accompanied by huge corrections in height distributions and average local slopes, as well as in estimates of scaling exponents. The molecular-beam epitaxy model of Das Sarma and Tamborenea in 1+1 dimensions is a case example in which none of the proposed scaling relations works properly, while the other measured quantities do not converge to the expected asymptotic values. Thus, although roughness distributions are clearly better than other quantities to determine the universality class of a growing system, it is not the final solution for this task.Comment: 25 pages, including 9 figures and 1 tabl

Spatial patterns and biodiversity in off-lattice simulations of a cyclic three-species Lotka-Volterra model

Stochastic simulations of cyclic three-species spatial predator-prey models are usually performed in square lattices with nearest neighbor interactions starting from random initial conditions. In this Letter we describe the results of off-lattice Lotka-Volterra stochastic simulations, showing that the emergence of spiral patterns does occur for sufficiently high values of the (conserved) total density of individuals. We also investigate the dynamics in our simulations, finding an empirical relation characterizing the dependence of the characteristic peak frequency and amplitude on the total density. Finally, we study the impact of the total density on the extinction probability, showing how a low population density may jeopardize biodiversity.Comment: 5 pages, 7 figures; new version, with new title and figure

The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio

The $\textrm{A}^1\Pi-\textrm{X}^1\Sigma^+$ band system of carbon monoxide, which has been detected in six highly redshifted galaxies ($z=1.6-2.7$), is identified as a novel probe method to search for possible variations of the proton-electron mass ratio ($\mu$) on cosmological time scales. Laboratory wavelengths of the spectral lines of the A-X ($v$,0) bands for $v=0-9$ have been determined at an accuracy of $\Delta\lambda/\lambda=1.5 \times 10^{-7}$ through VUV Fourier-transform absorption spectroscopy, providing a comprehensive and accurate zero-redshift data set. For the (0,0) and (1,0) bands, two-photon Doppler-free laser spectroscopy has been applied at the $3 \times 10^{-8}$ accuracy level, verifying the absorption data. Sensitivity coefficients $K_{\mu}$ for a varying $\mu$ have been calculated for the CO A-X bands, so that an operational method results to search for $\mu$-variation.Comment: 7 pages (main article), 3 figures, includes supplementary materia

Comment on Bress et al. Effect of Intensive Versus Standard Blood Pressure Treatment According to Baseline Prediabetes Status: A Post Hoc Analysis of a Randomized Trial. Diabetes Care 2017;40:1401-1408.

info:eu-repo/semantics/publishedVersio

Thermal dependence of the zero-bias conductance through a nanostructure

We show that the conductance of a quantum wire side-coupled to a quantum dot, with a gate potential favoring the formation of a dot magnetic moment, is a universal function of the temperature. Universality prevails even if the currents through the dot and the wire interfere. We apply this result to the experimental data of Sato et al.[Phys. Rev. Lett. 95, 066801 (2005)].Comment: 6 pages, 3 figures. More detailed presentation, and updated references. Final version