A worldwide model for boundaries of urban settlements

The shape of urban settlements plays a fundamental role in their sustainable planning. Properly defining the boundaries of cities is challenging and remains an open problem in the Science of Cities. Here, we propose a worldwide model to define urban settlements beyond their administrative boundaries through a bottom-up approach that takes into account geographical biases intrinsically associated with most societies around the world, and reflected in their different regional growing dynamics. The generality of the model allows to study the scaling laws of cities at all geographical levels: countries, continents, and the entire world. Our definition of cities is robust and holds to one of the most famous results in Social Sciences: Zipf's law. According to our results, the largest cities in the world are not in line with what was recently reported by the United Nations. For example, we find that the largest city in the world is an agglomeration of several small settlements close to each other, connecting three large settlements: Alexandria, Cairo, and Luxor. Our definition of cities opens the doors to the study of the economy of cities in a systematic way independently of arbitrary definitions that employ administrative boundaries

Collaboration networks from a large CV database: dynamics, topology and bonus impact

Understanding the dynamics of research production and collaboration may reveal better strategies for scientific careers, academic institutions and funding agencies. Here we propose the use of a large and multidisciplinar database of scientific curricula in Brazil, namely, the Lattes Platform, to study patterns of scientific production and collaboration. In this database, detailed information about publications and researchers are made available by themselves so that coauthorship is unambiguous and individuals can be evaluated by scientific productivity, geographical location and field of expertise. Our results show that the collaboration network is growing exponentially for the last three decades, with a distribution of number of collaborators per researcher that approaches a power-law as the network gets older. Moreover, both the distributions of number of collaborators and production per researcher obey power-law behaviors, regardless of the geographical location or field, suggesting that the same universal mechanism might be responsible for network growth and productivity.We also show that the collaboration network under investigation displays a typical assortative mixing behavior, where teeming researchers (i.e., with high degree) tend to collaborate with others alike. Finally, our analysis reveals that the distinctive collaboration profile of researchers awarded with governmental scholarships suggests a strong bonus impact on their productivity.Comment: 8 pages, 8 figure

Bound states in the dynamics of a dipole in the presence of a conical defect

In this work we investigate the quantum dynamics of an electric dipole in a $(2+1)$-dimensional conical spacetime. For specific conditions, the Schr\"odinger equation is solved and bound states are found with the energy spectrum and eigenfunctions determined. We find that the bound states spectrum extends from minus infinity to zero with a point of accumulation at zero. This unphysical result is fixed when a finite radius for the defect is introduced.Comment: 4 page

A universal approach for drainage basins

Drainage basins are essential to Geohydrology and Biodiversity. Defining those regions in a simple, robust and efficient way is a constant challenge in Earth Science. Here, we introduce a model to delineate multiple drainage basins through an extension of the Invasion Percolation-Based Algorithm (IPBA). In order to prove the potential of our approach, we apply it to real and artificial datasets. We observe that the perimeter and area distributions of basins and anti-basins display long tails extending over several orders of magnitude and following approximately power-law behaviors. Moreover, the exponents of these power laws depend on spatial correlations and are invariant under the landscape orientation, not only for terrestrial, but lunar and martian landscapes. The terrestrial and martian results are statistically identical, which suggests that a hypothetical martian river would present similarity to the terrestrial rivers. Finally, we propose a theoretical value for the Hack's exponent based on the fractal dimension of watersheds, $\gamma=D/2$. We measure $\gamma=0.54 \pm 0.01$ for Earth, which is close to our estimation of $\gamma \approx 0.55$. Our study suggests that Hack's law can have its origin purely in the maximum and minimum lines of the landscapes.Comment: 20 pages, 6 Figures, and 1 Tabl

Sistema de gestão territorial da faixa de fronteira para a defesa agropecuária.

Os problemas sanitários agropecuários desconhecem fronteiras, principalmente quando há continuidade terrestre, como é o caso de faixa fronteiriça entre e o Paraguai, a Bolívia e o Peru. A Embrapa Monitoramento por Satélite e a Secretaria de Defesa Agropecuária do Ministério da Agricultura, Pecuária e Abastecimento desenvolveram um sistema de gestão territorial da faixa de fronteira para a defesa agropecuária com o objetivo principal de contribuir para a erradicação da febre aftosa. O sistema agrupa, organiza e disponibiliza informações espaciais detalhadas de toda faixa de fronteira internacional, compreendida entre os estados brasileiros do Acre, Rondônia, Mato Grosso e Mato Grosso do Sul e Peru, a Bolívia e o Paraguai. Para seu desenvolvimento, foi utilizada um base iconográfica composta por imagens dos satélites Landsat, CBERS, Eros e Spot. É fato que, ora a aplicação de todas as ferramentas fornecidas pelo sistema, é necessário que os agentes envolvidos percebam sua potencialidade. O sistema sozinho não é capaz de fornecer soluções para a erradicação da febre aftosa, assim como para o controle de outras zoonoses

Determinação automática de parâmetros morfométricos de bacias hidrográficas no município de Campinas - SP.

A bacia hidrográfica se configura atualmente como umas das principais unidades de gerenciamento territorial que dispomos nas atividades agrossilvipastoris, sendo modelada pelas condições geológicas e climáticas locais. Os dados de sensoriamento remoto orbital atendem à necessidade de informação em diversas escalas, representando um meio viável de monitoramento da superfície terrestre através de satélites e seus sensores, e vem servindo de fonte de informações para estudos e levantamentos geológicos, agrícola cartográficos, florestais, urbanos, entre outros. Esta pesquisa tem pretende fornecer um retrato da situação atual dos canais fluviais e pluviais das bacias hidrográficas dos ribeirões Anhumas e Quilombo, e dos rios Capivari, Capivari-Mirim, Jaguari e Atibaia no Município de Campinas, a partir da confecção de um aplicativo em Arc Macro Language (AML) para automatizar a extração de parâmetros morfométricos, possibilitando uma análise temporal da evolução dos canais fluviais, a qual é fundamental para a aplicação de medidas mitigadoras e voltadas para o gerenciamento dos rios

Self-Forces on Electric and Magnetic Linear Sources in the Space-Time of a Cosmic String

In this paper we calculate the magnetic and electric self-forces, induced by the conical structure of a cosmic string space-time, on a long straight wire which presents either a constant current or a linear charge density. We also show how these self-forces are related by a Lorentz tranformation and, in this way, explain what two different inertial observers detect in their respective frames.Comment: 10 pages, LaTeX, to be published in Phys. Rev. D

Processamento de "Pimenta Dedo-de-Moça" (Capsicum baccatum var. pendulum) em conserva.

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