A Monte Carlo Approach to Measure the Robustness of Boolean Networks

Emergence of robustness in biological networks is a paramount feature of evolving organisms, but a study of this property in vivo, for any level of representation such as Genetic, Metabolic, or Neuronal Networks, is a very hard challenge. In the case of Genetic Networks, mathematical models have been used in this context to provide insights on their robustness, but even in relatively simple formulations, such as Boolean Networks (BN), it might not be feasible to compute some measures for large system sizes. We describe in this work a Monte Carlo approach to calculate the size of the largest basin of attraction of a BN, which is intrinsically associated with its robustness, that can be used regardless the network size. We show the stability of our method through finite-size analysis and validate it with a full search on small networks.Comment: on 1st International Workshop on Robustness and Stability of Biological Systems and Computational Solutions (WRSBS

Breathing synchronization in interconnected networks

Global synchronization in a complex network of oscillators emerges from the interplay between its topology and the dynamics of the pairwise interactions among its numerous components. When oscillators are spatially separated, however, a time delay appears in the interaction which might obstruct synchronization. Here we study the synchronization properties of interconnected networks of oscillators with a time delay between networks and analyze the dynamics as a function of the couplings and communication lag. We discover a new breathing synchronization regime, where two groups appear in each network synchronized at different frequencies. Each group has a counterpart in the opposite network, one group is in phase and the other in anti-phase with their counterpart. For strong couplings, instead, networks are internally synchronized but a phase shift between them might occur. The implications of our findings on several socio-technical and biological systems are discussed.Comment: 7 pages, 3 figures + 3 pages of Supplemental Materia

Critical Cooperation Range to Improve Spatial Network Robustness

A robust worldwide air-transportation network (WAN) is one that minimizes the number of stranded passengers under a sequence of airport closures. Building on top of this realistic example, here we address how spatial network robustness can profit from cooperation between local actors. We swap a series of links within a certain distance, a cooperation range, while following typical constraints of spatially embedded networks. We find that the network robustness is only improved above a critical cooperation range. Such improvement can be described in the framework of a continuum transition, where the critical exponents depend on the spatial correlation of connected nodes. For the WAN we show that, except for Australia, all continental networks fall into the same universality class. Practical implications of this result are also discussed

Directed Random Markets: Connectivity determines Money

Boltzmann-Gibbs distribution arises as the statistical equilibrium probability distribution of money among the agents of a closed economic system where random and undirected exchanges are allowed. When considering a model with uniform savings in the exchanges, the final distribution is close to the gamma family. In this work, we implement these exchange rules on networks and we find that these stationary probability distributions are robust and they are not affected by the topology of the underlying network. We introduce a new family of interactions: random but directed ones. In this case, it is found the topology to be determinant and the mean money per economic agent is related to the degree of the node representing the agent in the network. The relation between the mean money per economic agent and its degree is shown to be linear.Comment: 14 pages, 6 figure

Organização de comunidades de besouros rola-bosta (Coleoptera, Scarabaeidae) em áreas de re-estabelecimento de vegetação em Feira de Santana, Bahia, Brasil

The present work refers to the study of colonization of four vegetation physiognomies considered as succession stages by Scarabaeidae beetles in Feira de Santana, Brazil. The four environments present structures of 1) herbs, 2) herbs and bushes, 3) bushes, and 4) bushes and trees. The last one has similar vegetation elements to the original vegetation of the area (Caatinga, in transition with deciduous forest). Beetles’ richness was not statistically different in the three structurally simpler habitats, the composition, as well as the abundance structure of the communities of the four sites were very similar. Guild structure changed in number and proportion of specimens, with an increase in the number of tunnelers as the vegetation grew in complexity. The positive/negatives effects on the composition and beetles’s community structure were related to the interference with the dissemination of odor plumes or maintenance of sources of resources (vertebrates). The organization of the functional structure in the beetles’ community should be related to the time needed for the establishment of complex ecological connections.O presente trabalho refere-se ao estudo de colonização de quatro fisionomias de vegetação consideradas como estágios sucessionais, em Feira de Santana, Brasil, por besouros Scarabaeidae. Os quatro ambientes possuem estruturas: 1) herbácea, 2) herbácea/arbustiva, 3) arbustivo/arbórea e 4) arbórea. Esta última com elementos de vegetação similares à vegetação original da área (Caatinga, em transição com floresta decídua). A riqueza de besouros não foi estatisticamente diferente nos três ambientes estruturalmente mais simples, e tanto a composição quanto a estrutura de abundância das comunidades dos quatro sítios foram muito semelhantes. A estrutura de guildas mudou em número e proporção de espécies, com aumento no número de “escavadores” com o aumento na complexidade estrutural da vegetação, cujos efeitos positivos / negativos sobre a composição e estrutura da comunidade de besouros foi relacionado à interferência sobre a disseminação de plumas de odor ou manutenção de fontes de recursos (vertebrados). A organização da estrutura funcional da comunidade de besouros deve ser relacionada ao tempo necessário para o estabelecimento de conexões ecológicas complexas.O presente trabalho refere-se ao estudo de colonização de quatro fisionomias de vegetação consideradas como estágios sucessionais, em Feira de Santana, Brasil, por besouros Scarabaeidae. Os quatro ambientes possuem estruturas: 1) herbácea, 2) herbácea/arbustiva, 3) arbustivo/arbórea e 4) arbórea. Esta última com elementos de vegetação similares à vegetação original da área (Caatinga, em transição com floresta decídua). A riqueza de besouros não foi estatisticamente diferente nos três ambientes estruturalmente mais simples, e tanto a composição quanto a estrutura de abundância das comunidades dos quatro sítios foram muito semelhantes. A estrutura de guildas mudou em número e proporção de espécies, com aumento no número de “escavadores” com o aumento na complexidade estrutural da vegetação, cujos efeitos positivos / negativos sobre a composição e estrutura da comunidade de besouros foi relacionado à interferência sobre a disseminação de plumas de odor ou manutenção de fontes de recursos (vertebrados). A organização da estrutura funcional da comunidade de besouros deve ser relacionada ao tempo necessário para o estabelecimento de conexões ecológicas complexas

Efeito da densidade do solo na incidência de Fusarium spp.

O objetivo deste trabalho foi avaliar o efeito da densidade do solo resultante de dois sistemas de manejo e seis rotações de culturas na população de Fusarium spp

Infusão de antibiótico via veia digital palmar em cavalos da raça Puro-Sangue-Inglês

O artigo não apresenta resumo

Similarities and Differences in the Peripheral Actions of Thyroid Hormones and Their Metabolites

Thyroxine (T4) and 3,5,3'-triiodothyronine (T3) are secreted by the thyroid gland, while T3 is also generated from the peripheral metabolism of T4 by iodothyronine deiodinases types I and II. Several conditions like stress, diseases, and physical exercise can promote changes in local TH metabolism, leading to different target tissue effects that depend on the presence of tissue-specific enzymatic activities. The newly discovered physiological and pharmacological actions of T4 and T3 metabolites, such as 3,5-diiodothyronine (3,5-T2), and 3-iodothyronamine (T1AM) are of great interest. A classical thyroid hormone effect is the ability of T3 to increase oxygen consumption in almost all cell types studied. Approximately 30 years ago, a seminal report has shown that 3,5-T2 increased oxygen consumption more rapidly than T3 in hepatocytes. Other studies demonstrated that exogenous 3,5-T2 administration was able to increase whole body energy expenditure in rodents and humans. In fact, 3,5-T2 treatment prevents diabetic nephropathy, hepatic steatosis induced by high fat diet, insulin resistance, and weight gain during aging in Wistar male rats. The regulation of mitochondria is likely one of the most important actions of T3 and its metabolite 3,5-T2, which was able to restore the thermogenic program of brown adipose tissue (BAT) in hypothyroid rats, just as T3 does, while T1AM administration induced rapid hypothermia. T3 increases heart rate and cardiac contractility, which are hallmark effects of hyperthyroidism involved in cardiac arrhythmia. These deleterious cardiac effects were not observed with the use of 3,5-T2 pharmacological doses, and in contrast T1AM was shown to promote a negative inotropic and chronotropic action at micromolar concentrations in isolated hearts. Furthermore, T1AM has a cardioprotective effect in a model of ischemic/reperfusion injury in isolated hearts, such as occurs with T3 administration. Despite the encouraging possible therapeutic use of TH metabolites, further studies are needed to better understand their peripheral effects, when compared to T3 itself, in order to establish their risk and benefit. On this basis, the main peripheral effects of thyroid hormones and their metabolites in tissues, such as heart, liver, skeletal muscle, and BAT are discussed herein