Modeling Worldwide Highway Networks

This letter addresses the problem of modeling the highway systems of different countries by using complex networks formalism. More specifically, we compare two traditional geographical models with a modified geometrical network model where paths, rather than edges, are incorporated at each step between the origin and destination nodes. Optimal configurations of parameters are obtained for each model and used in the comparison. The highway networks of Brazil, the US and England are considered and shown to be properly modeled by the modified geographical model. The Brazilian highway network yielded small deviations that are potentially accountable by specific developing and sociogeographic features of that country.Comment: 5 pages, 3 figures, 1 tabl

SUBCONTRATAÇÃO E INFORMALIDADE NA CONSTRUÇÃO CIVIL, NO BRASIL E NA FRANÇA

Este artigo apresenta uma análise comparativa do mercado de trabalho do setor da Construção Civil, no Brasil e na França, em um contexto de flexibilização. Fruto de pesquisas de campo em canteiros de obras, nesses dois países, o texto aborda especificidades da informalidade dos contratos de trabalho no setor, que vêm produzindo uma transferência das ilegalidades das grandes para as pequenas empresas. No caso Francês, mediante as agências de temporários. No Brasil, através das pequenas empresas clandestinas, denominadas “gatas”. Enfatizam-se a percepção dos trabalhadores frente às ilegalidades e suas estratégias para se manter no mercado. No caso Francês, ressalta-se o trabalho de imigrantes clandestinos ou portadores de títulos de estadia precários, viabilizados pelas agências de temporários. No Brasil, percebe-se que o setor sempre se organizou com base na informalidade e busca, aos poucos, fidelizar os trabalhadores, ainda que se mantenha predominante o trabalho informal.PALAVRAS-CHAVE: informalidade, subcontratação, construção civil, trabalho, precariedade.SUBCONTRACTING AND INFORMALITY IN CIVIL CONSTRUCTION, IN BRAZIL AND FRANCE Luciano Rodrigues CostaThis paper presents a comparative analysis of the labor market of the construction industry in Brazil and France, in a context of flexibility. This text, being the result of field research on construction sites in these two countries, discusses specifics of the informal labor contracts in the sector, which have produced a transfer of illegalities from large to small businesses. In the French case, through temporary agencies. In Brazil, through small businesses underground, called “kittens. ”The perception of workers against such illegalities and their strategies to stay on the market are emphasized. In the French case, the work of illegal or semi-legal immigrants, made possible by temporary agencies. In Brazil, it is clear that the industry has always been organized based on informality and seeks, gradually, to retain workers, even though informal work remains predominant.KEYWORDS: informality, subcontracting, civil construction, labor, precariousness.SOUS-TRAITANCE ET INFORMALITÉ DANS LA CONSTRUCTION CIVILE, AU BRÉSIL ET EN FRANCE Luciano Rodrigues CostaCet article présente une analyse comparative du marché du travail dans la Construction Civile au Brésil et en France, dans un contexte de flexibilité. Fruit des recherches de terrain effectuées sur des chantiers de construction dans ces deux pays, ce texte aborde les spécificités des contrats de travail informels dans le secteur qui entrainent un transfert d’illégalités des grandes aux petites entreprises. Dans le cas français, ceci se fait par le biais des agences d’intérim, au Brésil, par le biais des petites entreprises clandestines, appelées “gatas”. On y souligne la perception de ces illégalités par les travailleurs et les stratégies utilisées pour rester sur le marché. Dans le cas français, l’accent est mis sur le travail des immigrés clandestins ou porteurs de titres de séjour précaires, rendus possibles par les agences de travail intérimaire. Au Brésil on peut se rendre compte que le secteur a toujours été organisé sur la base de l’informel mais cherche progressivement à fidéliser les ouvriers, même si le travail informel reste prédominant.MOTS-CLÉS: informalité, sous-traitance, construction civile, travail, précarité. Publicação Online do Caderno CRH: http://www.cadernocrh.ufba.br   Publicação Online do Caderno CRH no Scielo: http://www.scielo.br/ccr

Signal Propagation in Cortical Networks: A Digital Signal Processing Approach

This work reports a digital signal processing approach to representing and modeling transmission and combination of signals in cortical networks. The signal dynamics is modeled in terms of diffusion, which allows the information processing undergone between any pair of nodes to be fully characterized in terms of a finite impulse response (FIR) filter. Diffusion without and with time decay are investigated. All filters underlying the cat and macaque cortical organization are found to be of low-pass nature, allowing the cortical signal processing to be summarized in terms of the respective cutoff frequencies (a high cutoff frequency meaning little alteration of signals through their intermixing). Several findings are reported and discussed, including the fact that the incorporation of temporal activity decay tends to provide more diversified cutoff frequencies. Different filtering intensity is observed for each community in those networks. In addition, the brain regions involved in object recognition tend to present the highest cutoff frequencies for both the cat and macaque networks

Seeking for Simplicity in Complex Networks

Complex networks can be understood as graphs whose connectivity deviates from those of regular or near-regular graphs, which are understood as being `simple'. While a great deal of the attention so far dedicated to complex networks has been duly driven by the `complex' nature of these structures, in this work we address the identification of simplicity, in the sense of regularity, in complex networks. The basic idea is to seek for subgraphs exhibiting small dispersion (e.g. standard deviation or entropy) of local measurements such as the node degree and clustering coefficient. This approach paves the way for the identification of subgraphs (patches) with nearly uniform connectivity, therefore complementing the characterization of the complexity of networks. We also performed analysis of cascade failures, revealing that the removal of vertices in `simple' regions results in smaller damage to the network structure than the removal of vertices in the heterogeneous regions. We illustrate the potential of the proposed methodology with respect to four theoretical models as well as protein-protein interaction networks of three different species. Our results suggest that the simplicity of protein interaction grows as the result of natural selection. This increase in simplicity makes these networks more robust to cascade failures.Comment: 5 pages, 3 figures, 1 table. Submitted to Physical Review Letter

Border trees of complex networks

The comprehensive characterization of the structure of complex networks is essential to understand the dynamical processes which guide their evolution. The discovery of the scale-free distribution and the small world property of real networks were fundamental to stimulate more realistic models and to understand some dynamical processes such as network growth. However, properties related to the network borders (nodes with degree equal to one), one of its most fragile parts, remain little investigated and understood. The border nodes may be involved in the evolution of structures such as geographical networks. Here we analyze complex networks by looking for border trees, which are defined as the subgraphs without cycles connected to the remainder of the network (containing cycles) and terminating into border nodes. In addition to describing an algorithm for identification of such tree subgraphs, we also consider a series of their measurements, including their number of vertices, number of leaves, and depth. We investigate the properties of border trees for several theoretical models as well as real-world networks.Comment: 5 pages, 1 figure, 2 tables. A working manuscript, comments and suggestions welcome