On the relation between Transversal and Longitudinal Scaling in Cities

Given that a group of cities follows a scaling law connecting urban population with socio-economic or infrastructural metrics (transversal scaling), should we expect that each city would follow the same behavior over time (longitudinal scaling)? This assumption has important policy implications, although rigorous empirical tests have been so far hindered by the lack of suitable data. Here, we advance the debate by looking into the temporal evolution of the scaling laws for 5507 municipalities in Brazil. We focus on the relationship between population size and two urban variables, GDP and water network length, analyzing the time evolution of the system of cities as well as their individual trajectory. We find that longitudinal (individual) scaling exponents are city-specific, but they are distributed around an average value that approaches to the transversal scaling exponent when the data are decomposed to eliminate external factors, and when we only consider cities with a sufficiently large growth rate. Such results give support to the idea that the longitudinal dynamics is a micro-scaling version of the transversal dynamics of the entire urban system. Finally, we propose a mathematical framework that connects the microscopic level to global behavior, and, in all analyzed cases, we find good agreement between theoretical prediction and empirical evidence

Irreversible magnetization under rotating fields and lock-in effect on ErBa_2Cu_3O_7 single crystal with columnar defects

We have measured the irreversible magnetization M_i of an ErBa_2Cu_3O_7 single crystal with columnar defects (CD), using a technique based on sample rotation under a fixed magnetic field H. This method is valid for samples whose magnetization vector remains perpendicular to the sample surface over a wide angle range - which is the case for platelets and thin films - and presents several advantages over measurements of M_L(H) loops at fixed angles. The resulting M_i(\Theta) curves for several temperatures show a peak in the CD direction at high fields. At lower fields, a very well defined plateau indicative of the vortex lock-in to the CD develops. The H dependence of the lock-in angle \phi_L follows the H^{-1} theoretical prediction, while the temperature dependence is in agreement with entropic smearing effects corresponding to short range vortex-defects interactions.Comment: 7 pages, 6 figures, to be published in Phys. Rev.

Grain yield adaptability and stability of blackeyed cowpea genotypes under rainfed agriculture in Brazil.

The present study aimed to evaluate the grain yield adaptability and stability of 20 blackeyed cowpea genotypes under rainfed agriculture in North, Northeastern and Central/Western Brazil

Production, breeding and potential of cowpea crop in Brazil.

About 50 years ago cowpea was reported as a relatively minor tropical legume. However, in the last years, it has been emerging as one of the most important food legume of the 21st century (SINGH, 2010). Brazil is not out of this panorama. Brazilian agriculture is undergoing major technological changes and, in addition, globalization in agribusiness has caused impacts on the production chain of several crops, particularly those heavily dependent on the use of a large volume of agricultural inputs, mainly fertilizers and pesticides. Such crops have had a higher production cost each year. On the other hand, this situation has brought new opportunities. Business farmers have sought new alternatives for their production arrangements. In this context cowpea constitutes one of the best options.bitstream/item/85620/1/Doc-216-Production.pd

Variação da densidade de fluxo de seiva e do potencial hídrico foliar nas faces leste e oeste da copa de laranjeira 'Valência'.

O objetivo deste trabalho foi avaliar a influência da variação diurna e sazonal dos fatores ambientais sobre a densidade de fluxo de seiva (DFS) e o potencial hídrico foliar (?f) nas faces leste e oeste da copa de laranjeiras ?Valência? em condições de sequeiro. Foram utilizadas três plantas para as avaliações, cujas linhas de plantio estavam orientadas no sentido norte-sul. As avaliações foram realizadas durante um dia, em cada época do ano: verão, outono, inverno e primavera. Os valores de potencial hídrico medidos antes do amanhecer variaram de -0,31 MPa, no dia 10-12-05, a -1,1 MPa, no dia 30-08-05, porém não houve diferença signifi cativa entre as faces leste e oeste da copa. Já para o potencial hídrico medido às 14h 30, em todas as épocas avaliadas, a face oeste apresentou menores (p<0,05) valores que os da face leste, sendo que os mesmos variaram entre -0,95 e -1,89 MPa, verifi cados nos dias 10-12-05 e 30-08-05, respectivamente. A maior demanda evaporativa que se verifi ca no período da tarde, induz a maior déficit hídrico na face oeste da copa, independentemente da época do ano e, por consequência, maior DFS em plantas bem hidratadas sob condições de dias completamente ensolarados. Em plantas em condições de defi ciência hídrica (indicada por baixos valores de ?f), a face oeste é mais sensível a essa situação, apresentando redução de DFS. Essa redução ocorre no inverno, na região de Cordeirópolis (SP)