Extensive bounds on the topological entropy of repellers in piecewise expanding coupled map lattices

International audienceBeyond the uncoupled regime, the rigorous description of the dynamics of (piecewise) expanding coupled map lattices remains largely incomplete. To address this issue, we study repellers of periodic chains of linearly coupled Lorenz-type maps which we analyze by means of symbolic dynamics. Whereas all symbolic codes are admissible for sufficiently small coupling intensity, when the interaction strength exceeds a chain length independent threshold, we prove that a large bunch of codes is pruned and an extensive decay follows suit for the topological entropy. This quantity however does not immediately drops off to 0. Instead, it is shown to be continuous at the threshold and to remain extensively bounded below by a positive number in a large part of the expanding regime. The analysis is firstly accomplished in a piecewise affine setting where all calculations are explicit and is then extended by continuation to CML based on $C^1$-perturbations of the individual map

Dynamical complexity of discrete time regulatory networks

Genetic regulatory networks are usually modeled by systems of coupled differential equations and by finite state models, better known as logical networks, are also used. In this paper we consider a class of models of regulatory networks which present both discrete and continuous aspects. Our models consist of a network of units, whose states are quantified by a continuous real variable. The state of each unit in the network evolves according to a contractive transformation chosen from a finite collection of possible transformations, according to a rule which depends on the state of the neighboring units. As a first approximation to the complete description of the dynamics of this networks we focus on a global characteristic, the dynamical complexity, related to the proliferation of distinguishable temporal behaviors. In this work we give explicit conditions under which explicit relations between the topological structure of the regulatory network, and the growth rate of the dynamical complexity can be established. We illustrate our results by means of some biologically motivated examples.Comment: 28 pages, 4 figure

Cellular aspects of wound healing

O processo cicatricial compreende uma sequência de eventos moleculares e celulares que interagem para que ocorra a restauração do tecido lesado. Desde o extravasamento de plasma, com a coagulação e agregação plaquetária até a reepitelização e remodelagem do tecido lesado o organismo age tentando restaurar a funcionalidade tecidual. Assim, este trabalho abrange os diversos aspectos celulares envolvidos no processo cicatricial, bem como os principais medicamentos utilizados no tratamento de patologias relacionadas às deficiências na cicatrização. São abordados também, os aspectos econômicos referentes, sobretudo, às feridas crônicas de pés diabéticos.Wound healing is a dynamic interactive process that involves a sequence of molecular and cellular events. Recent advances in cellular and molecular biology have greatly expanded our understanding of the biological process involved in wound repair and tissue regeneration. From plasma extravasation, with coagulation and platelet aggregation, to reepithelialization and remodeling of injured tissue, the organism acts by trying to restore functionality tissue. Thus, the present study encompasses several cellular aspects involved in the wound healing process, as well as the main drugs used in treating the pathology related to wound healing complications. Economic aspects are also addressed, mainly related to chronic wounds of diabetic feet.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)(FAEPA) Fundação de Apoio ao Ensino, Pesquisa e Assistênci

Effects of structural factors on upwelling fouling community, Southeast Brazil

To assess the successional pattern of fouling organisms three hypotheses were tested: 1) a thermocline is caused by seasonal upwelling events, and therefore, depth influences the successional trajectory of the fouling community; 2) a reduction in the intensity of natural light of the substrate influences the fouling composition and the successional trajectory; 3) fish predation influences the community composition and its successional trajectory. During one year, up-facing and down-facing PVC panels on open, partially caged or fully caged, and placed at depths of 1.5 and 3.5 meters were monthly sampled by digital photograph to determine the community composition and by contact point to estimate the percent coverage of organisms. The upwelling impact provided different water masses, and light intensity was also a determining factor of the overall successional trajectory of the fouling community. After the installation of full and partial cages, differences were identified in the respective successional trajectories. The results of this study suggest that each physical factor or biological process can change the successional trajectory of the community, and the successional model (e.g., convergent, divergent, parallel, or cyclic) depends on the magnitudes of the determinants that act on the community at each stage of its trajectory.Para avaliar o padrão sucessional de organismos incrustantes, três hipóteses foram testadas: 1) uma termoclina é causada por eventos de ressurgência e, portanto, a profundidade influencia na trajetória sucessional da comunidade incrustante; 2) a redução na intensidade de luz natural no substrato influencia a composição da comunidade e a trajetória sucessional; 3) a predação por peixes influencia a composição da comunidade e sua trajetória sucessional. Durante um ano, faces inferiores e superiores de painéis de PVC em gaiolas abertas, parcial e totalmente fechadas em profundidades de 1,5 e 3,5 metros foram amostradas mensalmente por fotografia digital para determinar a composição da comunidade por ponto-contato e estimar a porcentagem de cobertura dos organismos. Diferentes massas de água resultantes da ressurgência e diferentes intensidades de luz foram fatores determinantes na trajetória sucessional da comunidade. Após a instalação de gaiolas parcial e totalmente fechadas, foram identificadas diferenças nas respectivas trajetórias. O resultado deste estudo sugere que cada fator físico ou processo biológico pode alterar a trajetória de desenvolvimento de uma comunidade, e o modelo sucessional (ex. convergente, divergente, paralelo ou cíclico) depende da magnitude dos fatores determinantes que atuam em cada etapa de sua trajetória

Successional trajectory of the fouling community on a tropical upwelling ecosystem in southeast Rio de Janeiro, Brazil

Resumo O presente estudo descreve a trajetória sucessional da comunidade incrustante na região de ressurgência de Cabo Frio no sudeste do Rio de Janeiro, Brasil. Durante 12 meses, cinco painéis de PVC foram amostrados mensalmente por fotografia subaquática para registrar a porcentagem de cobertura dos organismos incrustantes, permitindo a avaliação do processo sucessional através de grupos funcionais. A variabilidade na composição da comunidade incrustante aumentou ao longo de toda a trajetória sucessional, criando um padrão de mosaico. A identificação de duas associações após um ano de observação, sendo uma caracterizada por algas filamentosas, Hydrozoa e Cirripedia, e outra principalmente por algas calcáreas articuladas, evidencia que diferentes trajetórias podem ser observadas inclusive quando iniciadas sob mesmas condições ambientais. Como um importante fator sazonal das características oceanográficas locais, os eventos de ressurgência favoreceram uma heterogeneidade ambiental, rejeitando o clássico modelo sucessional ordenado e direcional.Abstract The present study describes the successional trajectory of the fouling community in the upwelling region of Cabo Frio in southeastern Rio de Janeiro, Brazil. For 12 months, five PVC panels were sampled monthly by underwater photography to record the percent cover of fouling organisms, which allowed for the evaluation of the successional process through functional groups. The variability in the composition of the fouling community increased throughout the successional trajectory, creating a mosaic pattern. The identification of two associations after a year of observation, with one characterized by filamentous algae, Hydrozoa and Cirripedia and another mainly by articulated calcareous algae, shows that divergent trajectories can be observed even under the same environmental conditions. As an important seasonal factor of the local oceanographic characteristics, the upwelling events allowed for an environmental heterogeneity, and rejecting the classic orderly and directional succession model

Semantic Search of Mobile Applications Using Word Embeddings

This paper proposes a set of approaches for the semantic search of mobile applications, based on their name and on the unstructured textual information contained in their description. The proposed approaches make use of word-level, character-level, and contextual word-embeddings that have been trained or fine-tuned using a dataset of about 500 thousand mobile apps, collected in the scope of this work. The proposed approaches have been evaluated using a public dataset that includes information about 43 thousand applications, and 56 manually annotated non-exact queries. Our results show that both character-level embeddings trained on our data, and fine-tuned RoBERTa models surpass the performance of the other existing retrieval strategies reported in the literature