Electromagnetic structure and weak decay of pseudoscalar mesons in a light-front QCD-inspired model

We study the scaling of the $^3S_1-^1S_0$ meson mass splitting and the pseudoscalar weak decay constants with the mass of the meson, as seen in the available experimental data. We use an effective light-front QCD-inspired dynamical model regulated at short-distances to describe the valence component of the pseudoscalar mesons. The experimentally known values of the mass splittings, decay constants (from global lattice-QCD averages) and the pion charge form factor up to 4 [GeV/c]$^2$ are reasonably described by the modelComment: 27 Pages, 7 eps figures,use revtex

Biofouling in water systems

The paper describes the mechanisms in the development of biofouling layers (initial surface conditioning, microbial transport and attachment, mass transfer of nutrients to the biofilm surface and through the microbial layer, cell metabolism, and detachment of cells and of larger parts of the biofilm) and summarizes the effects of several factors on the buildup and stability of biofilms (nutrient availability, fluid velocity and turbulence, temperature, surface condition, and nonliving particles). Mass transfer within biofilms is treated in more detail. A biofouling model applied to the development of biofilms in heat exchangers is presented. Finally, references are made to biofouling control methods (biocide and the proper design and operation of heat exchangers) and to future research needs in this area

Weak decay constant of pseudscalar meson in a QCD-inspired model

We show that a linear scaling between the weak decay constants of pseudoscalar and the vector mesons masses is supported by the available experimental data. The decay constant scale as $f_m/f_{pi}=M_V/M_{\rho}$ (f_m is decay constant and M_V vector meson ground state mass). This simple form is justified within a renormalized light-front QCD-inpired model for quark-antiquark bound states.Comment: 4 pages, use revtex style. To appear "Brazilian Journal of Physics (2003)

Desenvolvimento de uma metodologia baseada na técnica fotoacústica para determinar porosidades em membranas vítreas porosas.

Este trabalho trata do desenvolvimento de um método fotoacústico para a determinação da porosidade de membranas vítreas, as quais são utilizadas como meios filtrantes. As membranas foram produzidas com diferentes porcentagens de poros: 10%, 20%, 30% e 40%, através da técnica de preenchimento. Após a sinterização das membranas, dois diferentes processos independentes foram realizados para a eliminação do material inerte e uniformização da espessura: i) membranas primeiro lavadas e depois lixadas; ii) membranas primeiro lixadas e depois lavadas. As medidas fotoacústicas das membranas com diferentes porosidades foram obtidas nas condições de varredura de freqüência de modulação de 12 a 500 Hz e utilizando-se a luz branca. O desenvolvimento da metodologia consiste em utilizar dois tipos de suporte de amostra, um denominado por "branco" e outro por "preto", para as medidas fotoacústicas. Para cada amostra nos suportes citados, as amplitudes dos sinais fotoacústicos foram diferentes durante a varredura de freqüência de modulação da luz. Estas amplitudes foram relacionadas entre si e normalizadas pela massa da membrana. Todo este procedimento foi aplicado a todas as membranas, possibilitando a distinção entre aquelas de diferentes porosidades.bitstream/CNPDIA/8124/1/BPD01_2002.pd

A MILP model for an extended version of the Flexible Job Shop Problem

A MILP model for an extended version of the Flexible Job Shop Scheduling problem is proposed. The extension allows the precedences between operations of a job to be given by an arbitrary directed acyclic graph rather than a linear order. The goal is the minimization of the makespan. Theoretical and practical advantages of the proposed model are discussed. Numerical experiments show the performance of a commercial exact solver when applied to the proposed model. The new model is also compared with a simple extension of the model described by \"Ozg\"uven, \"Ozbakir, and Yavuz (Mathematical models for job-shop scheduling problems with routing and process plan flexibility, Applied Mathematical Modelling, 34:1539--1548, 2010), using instances from the literature and instances inspired by real data from the printing industry.Comment: 15 pages, 2 figures, 4 tables. Optimization Letters, 201