Boolean networks with reliable dynamics

We investigated the properties of Boolean networks that follow a given reliable trajectory in state space. A reliable trajectory is defined as a sequence of states which is independent of the order in which the nodes are updated. We explored numerically the topology, the update functions, and the state space structure of these networks, which we constructed using a minimum number of links and the simplest update functions. We found that the clustering coefficient is larger than in random networks, and that the probability distribution of three-node motifs is similar to that found in gene regulation networks. Among the update functions, only a subset of all possible functions occur, and they can be classified according to their probability. More homogeneous functions occur more often, leading to a dominance of canalyzing functions. Finally, we studied the entire state space of the networks. We observed that with increasing systems size, fixed points become more dominant, moving the networks close to the frozen phase.Comment: 11 Pages, 15 figure

Network of recurrent events for the Olami-Feder-Christensen model

We numerically study the dynamics of a discrete spring-block model introduced by Olami, Feder and Christensen (OFC) to mimic earthquakes and investigate to which extent this simple model is able to reproduce the observed spatiotemporal clustering of seismicty. Following a recently proposed method to characterize such clustering by networks of recurrent events [Geophys. Res. Lett. {\bf 33}, L1304, 2006], we find that for synthetic catalogs generated by the OFC model these networks have many non-trivial statistical properties. This includes characteristic degree distributions -- very similar to what has been observed for real seismicity. There are, however, also significant differences between the OFC model and earthquake catalogs indicating that this simple model is insufficient to account for certain aspects of the spatiotemporal clustering of seismicity.Comment: 11 pages, 16 figure

Renormalization Ambiguities and Conformal Anomaly in Metric-Scalar Backgrounds

We analyze the problem of the existing ambiguities in the conformal anomaly in theories with external scalar field in curved backgrounds. In particular, we consider the anomaly of self-interacting massive scalar field theory and of Yukawa model in the massless conformal limit. In all cases the ambiguities are related to finite renormalizations of a local non-minimal terms in the effective action. We point out the generic nature of this phenomenon and provide a general method to identify the theories where such an ambiguity can arise.Comment: RevTeX, 10 pages, no figures. Small comment and two references added. Accepted for publication in Physical Review

Caracterização comparativa de propriedades que desenvolvem atividade pecuária em assentamentos rurais de Tomé-Açu e Paragominas: manejo das pastagens, acesso as estradas e nível de produtividade.

O presente estudo buscou efetuar a caracterização do manejo das pastagens, bem como as condições das estradas de acesso e o nível de produtividade de propriedades envolvidas com a atividade pecuária em assentamentos rurais de Tomé-Açu e Paragominas, as quais estão localizadas no Nordeste e Sudeste paraense, respectivamente. Noventa e cinco produtores foram entrevistados quanto à presença ou não de áreas de pastagens quando da aquisição das propriedades, assim como quanto à formação de novas áreas, uso do fogo, tipo de gramínea presente na pastagem, período de utilização de um mesmo pasto, vacinação contra febre aftosa, utilização de mistura mineral, produção diária de leite e quanto às condições de trafegabilidade das estradas que dão acesso às propriedades durante o período chuvoso. Foi observado que a atividade pecuária não é viável nas propriedades investigadas em razão da baixa adoção tecnológica e produtividade dos rebanhos. A cobertura vacinal foi insuficiente o que coloca em risco todo o setor produtivo da pecuária. As forrageiras presentes nas propriedades basicamente foram a Brachiaria brizantha cv Marandú e a Brachiaria humidicula, o que revela o risco quanto à incidência de pragas e doenças

Classical and quantum coupled oscillators: symplectic structure

We consider a set of N linearly coupled harmonic oscillators and show that the diagonalization of this problem can be put in geometrical terms. The matrix techniques developed here allowed for solutions in both the classical and quantum regimes.Comment: 27 pages, 6 figure

Specific plasmid patterns and high rates of bacterial co-occurrence within the coral holobiont

Despite the importance of coral microbiomes for holobiont persistence, the interactions among these arenot well understood. In particular, knowledge of the co-occurrence and taxonomic importance of specific members of the microbial core, as well as patterns of specific mobile genetic elements (MGEs), is lacking. We used seawater and mucus samples collected from Mussismilia hispida colonies on two reefs located in Bahia, Brazil, to disentangle their associated bacterial communities, intertaxa correlations, and plasmid patterns. Proxies for two broad-host-range (BHR) plasmid groups, IncP-1 and PromA, were screened. Both groups were significantly (up to 252 and 100%, respectively) more abundant in coral mucus than in seawater. Notably, the PromA plasmid group was detected only in coral mucus samples. The core bacteriome of M.hispidamucus was composed primarily of members of the Proteobacteria, followed by those of Firmicutes. Significant host specificity and co-occurrences among different groups of the dominant phyla (e.g., Bacillaceae and Pseudoalteromonadaceae and the genera Pseudomonas, Bacillus, and Vibrio) were detected. These relationships were observed for both the most abundant phyla and the bacteriome core, in which most of the operational taxonomic units showed intertaxa correlations. The observed evidence of host-specific bacteriome and co-occurrence (and potential symbioses or niche space co-dominance) among the most dominant members indicates a taxonomic selection of members of the stable bacterial community. In parallel, host-specific plasmid patterns could also be, independently, related to the assembly of members of the coral microbiome

Desempenho de cultivares de batata-doce no Distrito federal.

O presente trabalho teve como objetivo avaliar o desempenho agronômico de seis cultivares e três variedades de batata-doce nas condições edafoclimáticas no Recanto das Emas, DF