Emergence of robustness against noise: A structural phase transition in evolved models of gene regulatory networks

We investigate the evolution of Boolean networks subject to a selective pressure which favors robustness against noise, as a model of evolved genetic regulatory systems. By mapping the evolutionary process into a statistical ensemble and minimizing its associated free energy, we find the structural properties which emerge as the selective pressure is increased and identify a phase transition from a random topology to a "segregated core" structure, where a smaller and more densely connected subset of the nodes is responsible for most of the regulation in the network. This segregated structure is very similar qualitatively to what is found in gene regulatory networks, where only a much smaller subset of genes --- those responsible for transcription factors --- is responsible for global regulation. We obtain the full phase diagram of the evolutionary process as a function of selective pressure and the average number of inputs per node. We compare the theoretical predictions with Monte Carlo simulations of evolved networks and with empirical data for Saccharomyces cerevisiae and Escherichia coli.Comment: 12 pages, 10 figure

Superdiffusion of massive particles induced by multi-scale velocity fields

We study drag-induced diffusion of massive particles in scale-free velocity fields, where superdiffusive behavior emerges due to the scale-free size distribution of the vortices of the underlying velocity field. The results show qualitative resemblance to what is observed in fluid systems, namely the diffusive exponent for the mean square separation of pairs of particles and the preferential concentration of the particles, both as a function of the response time.Comment: 5 pages, 5 figures. Accepted for publication in EP

Adaptações em colhedora automotriz para a colheita mecanizada de sementes de capim bufel (Cenchrus ciliaris L.).

O trabalho teve por objetivo estudar a possibilidade de utilizar uma colhedora automotriz, na colheita de sementes de capim bufel (Cenchrus ciliaris L.), uma gramínea de grande expressão econômica para a região semi-árida do Nordeste brasileiro. Trata-se de uma tecnologia adaptável às colhedoras automotrizes convencionais, com plataformas flexíveis utilizadas na colheita de soja ou trigo, desde que adotados alguns procedimentos como modificações do tubo de descarga de sementes, cobertura do caracol (inferior) situado no interior do graneleiro, peneiras de trilha e retrilha, sistema de circulação de ar, ajuste da altura da lâmina de corte e velocidade adequada de deslocamento do conjunto automotriz. O rendimento operacional depende do estado de maturação e da quantidade de sementes na área de capim a ser colhida. A tecnologia surge como um avanço tecnológico para a colheita mecanizada de sementes de capim bufel em grandes áreas, pois até então a colheita era efetuada manualmente ou com equipamentos semimecanizados (colhedoras manuais) de baixo rendimento operacional

A new approach to implement a customized anatomic insole in orthopaedic footwear of lower limb orthosis

This paper concerns the development of a new approach for orthopaedic footwear to apply in KAFO orthosis (acronym for Knee Ankle Foot Orthosis). This procedure starts with full characterization of the problem with the purpose to characterize a plantar of a patient’s foot with polio. A 3D Scanner was used to collect their feet's data to produce an anatomic insole. After this step, the patient performs a study of his gait using a static and dynamic study with the aim of characterizing the parameters to improve quality in the footwear. The insole was produced using a 3D printing technology. It was essential to optimize manufacturing processes and it was developed a footwear prototype with innovative characteristics, which is 25% lighter, allowing the user to consume less energy in daily routines.This work is supported by FEDER funding on the COMPETE program and by national funds through FCT-Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER- 007136 and UID/CTM/00264.info:eu-repo/semantics/publishedVersio

Tutorial TaxTools.

A ferramenta TaxTools foi desenvolvida pelo Laboratório de Inteligência Computacional (Labic) do Instituto de Ciência Matemática e de Computação (ICMC) da Universidade de São Paulo (USP), campus de São Carlos, SP, com o objetivo de auxiliar no processo de mineração de textos. Atualmente, ela tem sido mantida e evoluída pelo Laboratório de Inteligência Computacional (LabIC) da Embrapa Informática Agropecuária. Esse tutorial abrange apenas as opções disponíveis na TaxTools, que completam o processo de obtenção de uma taxonomia de tópicos (MOURA et al., 2008); como clusterização, cálculos de medidas intercluster e de joinability, métodos de podas, métodos de visualização de resultados e algumas opções auxiliares.bitstream/item/30572/1/doc104.pd

Leachate treatment process at a municipal stabilized landfill by catalytic ozonation: an exploratory study from Taguchi orthogonal array

Catalytic ozonation has been recognized in the scientific community as an efficient technique, reaching elevated rates of recalcitrant organic material mineralization, even at the presence of scavenger species of hydroxyl free radicals. This study presents the most significant factors involving the leachate treatment stabilized by the municipal landfill of the city of Guaratinguetá, State of São Paulo, Brazil, by using a catalytic ozonation activated by metallic ions Fe3+, Zn2+, Mn2+, Ni2+ and Cr3+. The Taguchi L16 orthogonal array and its associated statistical methods were also used in this study. Among the researched ions, the most notable catalysis was obtained with ferric ion, statistically significant in the reduction of COD with a confidence level of 99.5%.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Symmetry aspects of fermions coupled to torsion and electromagnetic fields

We study and explore the symmetry properties of fermions coupled to dynamical torsion and electromagnetic fields. The stability of the theory upon radiative corrections as well as the presence of anomalies are investigated.Comment: 9 pages, LaTe

The Network of Epicenters of the Olami-Feder-Christensen Model of Earthquakes

We study the dynamics of the Olami-Feder-Christensen (OFC) model of earthquakes, focusing on the behavior of sequences of epicenters regarded as a growing complex network. Besides making a detailed and quantitative study of the effects of the borders (the occurrence of epicenters is dominated by a strong border effect which does not scale with system size), we examine the degree distribution and the degree correlation of the graph. We detect sharp differences between the conservative and nonconservative regimes of the model. Removing border effects, the conservative regime exhibits a Poisson-like degree statistics and is uncorrelated, while the nonconservative has a broad power-law-like distribution of degrees (if the smallest events are ignored), which reproduces the observed behavior of real earthquakes. In this regime the graph has also a unusually strong degree correlation among the vertices with higher degree, which is the result of the existence of temporary attractors for the dynamics: as the system evolves, the epicenters concentrate increasingly on fewer sites, exhibiting strong synchronization, but eventually spread again over the lattice after a series of sufficiently large earthquakes. We propose an analytical description of the dynamics of this growing network, considering a Markov process network with hidden variables, which is able to account for the mentioned properties.Comment: 9 pages, 10 figures. Smaller number of figures, and minor text corrections and modifications. For version with full resolution images see http://fig.if.usp.br/~tpeixoto/cond-mat-0602244.pd

Kinetics of fluorene biodegradation by a mixed culture

The present study intended to determine the kinetics of biological degradation of fluorene by a mixed culture of microorganisms. Batch experiments were performed, being the inoculum an enriched mixed culture from a contaminated wastewater. Fluorene was quantified in the aqueous phase by solid phase micro-extraction (SPME), and analyzed in a GC-FID. The mixed culture was able to degrade fluorene and experimental results showed that biosorption had no influence on fluorene removal. The kinetic parameters, maximum reaction rate (kmax) and half saturation constant (Ks), respectively, 3.20×10–4 h–1 ± 0.93×10–4 h–1 and 126 μg L–1, were calculated