Reconstructing the Density of States by History-Dependent Metadynamics

We present a novel method for the calculation of the energy density of states D(E) for systems described by classical statistical mechanics. The method builds on an extension of a recently proposed strategy that allows the free energy profile of a canonical system to be recovered within a pre-assigned accuracy,[A. Laio and M. Parrinello, PNAS 2002]. The method allows a good control over the error on the recovered system entropy. This fact is exploited to obtain D(E) more efficiently by combining measurements at different temperatures. The accuracy and efficiency of the method are tested for the two-dimensional Ising model (up to size 50x50) by comparison with both exact results and previous studies. This method is a general one and should be applicable to more realistic model systems

Modelagem e simulação do tráfego de veículos e controle semafórico em um ambiente virtual

Simulate urban traffic realistically in a virtual environment is a complex task to implement, since many characteristics need to be developed. In this paper, we propose the use of different techniques to model and control the interaction of the elements of a simulation. In particular, we present a model physics-based for the vehicles to collisions avoid, an access control policy based on reserves and a model of synchronization of traffic signals using Petri net. The results show that the proposed model reproduces the behavior expected for the simulated contexts.Simular o trânsito de áreas urbanas de maneira realista em um ambiente virtual é uma tarefa complexa de ser implementada, pois muitas características precisam ser desenvolvidas. Neste trabalho, propomos a utilização de diversas técnicas para modelar e controlar a interação dos elementos constituintes de uma simulação. Em particular, apresentamos um modelo baseado em Física para que os veículos evitem colisões, uma política de controle de acesso a cruzamentos baseada em reservas e um modelo de sincronização de semáforos utilizando rede de Petri. Os resultados apresentados demonstram que os modelos propostos reproduzem os comportamentos esperados para os contextos simulados

Exact Curie temperature for the Ising model on Archimedean and Laves lattices

Using the Feynman-Vdovichenko combinatorial approach to the two dimensional Ising model, we determine the exact Curie temperature for all two dimensional Archimedean lattices. By means of duality, we extend our results to cover all two dimensional Laves lattices. For those lattices where the exact critical temperatures are not exactly known yet, we compare them with Monte Carlo simulations.Comment: 10 pages, 1 figures, 3 table

Proposta de um algoritmo de recomendação usando uma rede bayesiana no health simulator

Este artigo apresenta o projeto Health Simulator no contexto de inteligência artificial, no que se refere ao armazenamento do conhecimento especializado na área da saúde e estratégia pedagógica, que permite o auxílio ao aluno no seu processo de aprendizagem. Para tanto é apresentada a teoria de redes bayesianas, sistemas de recomendação, o projeto Health Simulator e a proposta de aplicação das técnicas utilizadas neste ambiente

Desenvolvimento de Um Simulador Controlado por Interface Cérebro- Computador Não Invasiva para Treinamento na Utilização de Cadeira de Rodas

Interface Cérebro-Computador (ICC) é um sistema computacional capaz de estabelecer a comunicação entre a atividade neurofisiológica e uma máquina computacional. Neste contexto, o presente trabalho tem como principal objetivo apresentar o desenvolvimento de um simulador de cadeira de rodas comandada por uma ICC não invasiva, utilizando um eletroencefalograma (EEG) de baixo custo. O simulador será utilizado para treinamento de pessoas com necessidades especiais para que, no momento de uso da cadeira, consigam controlá-la facilmente, evitando acidentes

Papain gel containing methylene blue for simultaneous caries removal and antimicrobial photoinactivation against Streptococcus mutans biofilms

This study intended to evaluate the effects of a papain-gel with a red-light absorbing pigment (methylene blue – MB) to mediate photodynamic therapy (PDT) against Streptococcus mutans biofilms. The PapaMBlue was compared with free MB to generate reactive oxygen species using fluorescence probes (SOSG and HPF). PDT (660-nm light) was carried out against S. mutans biofilms grown on either plastic dishes or on collagen membrane and assayed by CFU, live-dead staining using confocal microscopy, transmission electron microscopy and H&E staining for collagen films. Cytotoxicity and subcellular localization was studied in human fibroblasts. Sponges of bioabsorbable type I collagen membrane were exposed to papain based gel, irradiated with laser and analyzed about their integrity by ATR-FTIR. The PapaMBlue produced higher amounts of singlet oxygen and hydroxyl radicals than free MB, possibly due to better disaggregation of the dye in solution. The PapaMBlue antimicrobial effects on biofilms proved to be capable of reducing the S. mutans. Both MTT and PrestoBlue assays showed higher cell viability and metabolism scores in fibroblasts treated with PapaMBlue and MB, possibly due to stimulation of mitochondrial activity and that collagen triple helix is unaffected. The PapaMBlue is equally effective as MB in destroying S. mutans biofilms growing on plastic or collagen without affecting fibroblasts.National Institutes of Health (U.S.) (Grant R01AI050875

Darwin wasps: a new name heralds renewed efforts to unravel the evolutionary history of Ichneumonidae

The parasitoid wasp family Ichneumonidae is arguably one of the groups for which current knowledge lags most strongly behind their enormous diversity. In a five-day meeting in Basel (Switzerland) in June 2019, 22 researchers from 14 countries met to discuss the most important issues in ichneumonid research, including increasing the speed of species discovery, resolving higher-level relationships, and studying the radiation of these parasitoids onto various host groups through time. All agreed that it is time to advertise ichneumonid research more broadly and thereby attract young talents to this group for which specialists are sorely lacking, as well as increase public awareness about their exciting biology and ecological impact. In order to popularize the group, we here suggest a new vernacular name for the family, “Darwin wasps”, to reflect the pivotal role they played in convincing Charles Darwin that not all of creation could have been created by a benevolent god. We hope that the name catches on, and that Darwin wasps start buzzing more loudly across all disciplines of biology

Upscaling numérico baseado em uma metodologia multiescala para a simulação de escoamentos em reservatórios de petróleo heterogêneos e anisotrópicos / Numerical upscaling based on a multiscale methodology for simulating flows in heterogeneous and anisotropic oil reservoirs

This work aims to develop a scale transfer methodology in highly heterogeneous and anisotropic porous media, that makes it possible to solve elliptical problems with accuracy and low computational cost. A scale transfer method is developed that uses the Multiscale Finite Volume Method (MSFVM) to perform a flow based numerical upscaling of absolute permeability. The transmissibility matrix was built in the coarse mesh over the projection and restriction operators obtaining permeability in the coarse scale. This allows to solve only local problems in the coarse mesh volumes and to use pressure multiscale solution in the fine mesh. The permeability field can be obtained by different strategies, and enabling simulations directly on the coarse mesh, controlling the accuracy of the solutions and also with the possibility of updating the permeability field over the recalculated locally conservative multiscale solution. 

Cashew gum (Anacardium occidentale) as a potential source for the production of tocopherol-loaded nanoparticles: formulation, release profile and cytotoxicity

Every year, more than thirty thousand tons of Cashew gum (Anacardium occidentale, family: Anacardiaceae) are produced in Brazil; however, only a small amount is used for different applications in foodstuff and in pharmaceutical industries. As a raw material for the production of drug delivery systems, cashew gum is still regarded as an innovative compound worth to be exploited. In this work, cashew gum was extracted from the crude exudate of cashew tree employing four methodologies resulting in a light brown powder in different yields (40.61% to 58.40%). The total ashes (0.34% to 1.05%) and moisture (12.90% to 14.81%) were also dependent on the purification approach. FTIR spectra showed the typical bands of purified cashew gum samples, confirming their suitability for the development of a pharmaceutical product. Cashew gum nanoparticles were produced by nanoprecipitation resulting in particles of low polydispersity (<0.2) and an average size depending on the percentage of the oil. The zeta potential of nanoparticles was found to be below 20 mV, which promotes electrostatic stability. Encapsulation efficiencies were above 99.9%, while loading capacity increased with the increase of the percentage of the oil content of particles. The release of the oil from the nanoparticles followed the KorsmeyerPeppas kinetics model, while particles did not show any signs of toxicity when tested in three distinct cell lines (LLC-MK2, HepG2, and THP-1). Our study highlights the potential added value of using a protein-, lignans-, and nucleic acids-enriched resin obtained from crude extract as a new raw material for the production of drug delivery systems.This research received funding from the Coordenação Aperfeiçoamento de Pessoal de Nivel Superior (CAPES), Fundação de Ámparo à Pesquisa do Estado de Sergipe (FAPITEC) (PROCESSO: 88887.159533/2017-00 extração, encapsulação e caracterização de bioativos para o interesse biotecnologico) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq 301964/2019-0 Chamada 06/2019, and Chamada CNPq nº 01/2019), from Portuguese Foundation for Science and Technology (FCT/MEC) through national funds, and co-financed by FEDER, under the Partnership Agreement PT2020 for the project UIDB/04469/2020.info:eu-repo/semantics/publishedVersio