Characterization in bi-parameter space of a non-ideal oscillator

The authors thank scientific agencies CAPES, CNPq (112952/2015-1), and FAPESP (2011/ 19269-11). M. S. Baptista also thanks EPSRC (EP/I03 2606/1).Peer reviewedPostprin

Electron Spin Resonance of defects in the Haldane System Y(2)BaNiO(5)

We calculate the electron paramagnetic resonance (EPR) spectra of the antiferromagnetic spin-1 chain compound Y(2)BaNi(1-x)Mg(x)O(5) for different values of x and temperature T much lower than the Haldane gap (~100K). The low-energy spectrum of an anisotropic Heisenberg Hamiltonian, with all parameters determined from experiment, has been solved using DMRG. The observed EPR spectra are quantitatively reproduced by this model. The presence of end-chain S=1/2 states is clearly observed as the main peak in the spectrum and the remaining structure is completely understood.Comment: 5 pages, 4 figures include

Statistical Signs of Social Influence on Suicides

Certain currents in sociology consider society as being composed of autonomous individuals with independent psychologies. Others, however, deem our actions as strongly influenced by the accepted standards of social behavior. The later view was central to the positivist conception of society when in 1887 \'Emile Durkheim published his monograph Suicide (Durkheim, 1897). By treating the suicide as a social fact, Durkheim envisaged that suicide rates should be determined by the connections (or the lack of them) between people and society. Under the same framework, Durkheim considered that crime is bound up with the fundamental conditions of all social life and serves a social function. In this sense, and regardless of its extremely deviant nature, crime events are somehow capable to release certain social tensions and so have a purging effect in society. The social effect on the occurrence of homicides has been previously substantiated (Bettencourt et al., 2007; Alves et al., 2013), and confirmed here, in terms of a superlinear scaling relation: by doubling the population of a Brazilian city results in an average increment of 135 % in the number of homicides, rather than the expected isometric increase of 100 %, as found, for example, for the mortality due to car crashes. Here we present statistical signs of the social influence on the suicide occurrence in cities. Differently from homicides (superlinear) and fatal events in car crashes (isometric), we find sublinear scaling behavior between the number of suicides and city population, with allometric power-law exponents, $\beta = 0.836 \pm 0.009$ and $0.870 \pm 0.002$, for all cities in Brazil and US, respectively. The fact that the frequency of suicides is disproportionately small for larger cities reveals a surprisingly beneficial aspect of living and interacting in larger and more complex social networks.Comment: 7 pages, 4 figure

Complementary action of chemical and electrical synapses to perception

Acknowledgements This study was possible by partial financial support from the following agencies: Fundação Araucária, EPSRC-EP/I032606/1, CNPq No. 441553/2014-1, CAPES No. 17656-12-5 and Science Without Borders Program— Process Nos. 17656125, 99999.010583/2013-00 and 245377/2012-3.Peer reviewedPostprin

Sampling system for wheat (Triticum aestivum L) area estimation using digital LANDSAT MSS data and aerial photographs

A procedure to estimate wheat (Triticum aestivum L) area using sampling technique based on aerial photographs and digital LANDSAT MSS data is developed. Aerial photographs covering 720 square km are visually analyzed. To estimate wheat area, a regression approach is applied using different sample sizes and various sampling units. As the size of sampling unit decreased, the percentage of sampled area required to obtain similar estimation performance also decreased. The lowest percentage of the area sampled for wheat estimation with relatively high precision and accuracy through regression estimation is 13.90% using 10 square km as the sampling unit. Wheat area estimation using only aerial photographs is less precise and accurate than those obtained by regression estimation