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Aguirre, C., & Mendes, R. V. (2012). Signal recognition and adapted filtering by non-commutative tomography. Computing Research Repository, abs/1211.5986.
Abstract: Tomograms, a generalization of the Radon transform to arbitrary pairs of non-commuting operators, are positive bilinear transforms with a rigorous probabilistic interpretation which provide a full characterization of the signal and are robust in the presence of noise. Tomograms based on the time-frequency operator pair, were used in the past for component separation and denoising. Here we show how, by the construction of an operator pair adapted to the signal, meaningful information with good time resolution is extracted even in very noisy situations.
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Tatarova, E., Henriques, J. P., Felizardo, E., Lino da Silva, M., Ferreira, C. M., & Gordiets, B. (2012). Microwave plasma source operating with atmospheric pressure air-water mixtures. Journal of Applied Physics, 112(9), 093301.
Abstract: The overall performance of a surface wave driven air-water plasma source operating at atmospheric pressure and 2.45 GHz has been analyzed. A 1D model previously developed has been improved in order to describe in detail the creation and loss processes of active species of interest. This model provides a complete characterization of the axial structure of the source, including the discharge and the afterglow zones. The main electron creation channel was found to be the associative ionization process N + O -> NO+ + e. The NO(X) relative density in the afterglow plasma jet ranges from 1.2% to 1.6% depending on power and water percentage, according to the model predictions and the measurements. Other types of species such as NO2 and nitrous acid HNO2 have also been detected by mass and Fourier Transform Infrared spectroscopy. The relative population density of O(P-3) ground state atoms increases from 8% to 10% in the discharge zone when the input microwave power increases from 200 to 400W and the water percentage from 1% to 10%. Furthermore, high densities of O-2(a(1)Delta(g)) singlet delta oxygen molecules and OH radicals (1% and 5%, respectively) can be achieved in the discharge zone. In the late afterglow the O-2(a(1)Delta(g)) density is about 0.1% of the total density. This plasma source has a flexible operation and potential for channeling the energy in ways that maximize the density of active species of interest. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4762015]
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Mendes, R. V., & Aguirre, C. (2012). Cooperation, Punishment, Emergence of Government, and the Tragedy of Authorities. Complex Systems, 20(4), 363–374.
Abstract: Under the conditions prevalent in the late Pleistocene epoch (small hunter-gatherer groups and frequent inter-group conflicts), coevolution of gene-related behavior and culturally transmitted group-level institutions provides a plausible explanation for the parochial altruistic and reciprocator traits of most modern humans. When, with the agricultural revolution, societies became larger and more complex, the collective nature of the monitoring and punishment of norm violators was no longer effective. This led to the emergence of new institutions of governance and social hierarchies. The transition from an egalitarian society and the acceptance of the new institutions may have been possible only if, in the majority of the population, the reciprocator trait had become an internalized norm. However, the new ruling class has its own dynamics, which in turn may lead to a new social crisis. Using a simple model inspired by previous work by Bowles and Gintis, these effects are studied here.
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Mendes, R. V. (2012). A laboratory scale fundamental time? The European Physical Journal C, .
Abstract: The existence of a fundamental time (or fundamental length) has been conjectured in many contexts. However, the “stability of physical theories principle” seems to be the one that provides, through the tools of algebraic deformation theory, an unambiguous derivation of the stable structures that Nature might have chosen for its algebraic framework. It is well-known that c and h are the deformation parameters that stabilize the Galilean and the Poisson algebra. When the stability principle is applied to the Poincaré-Heisenberg algebra, two deformation parameters emerge which define two time (or length) scales. In addition there are, for each of them, a plus or minus sign possibility in the relevant commutators. One of the deformation length scales, related to non-commutativity of momenta, is probably related to the Planck length scale but the other might be much larger and already detectable in laboratory experiments. In this paper, this is used as a working hypothesis to look for physical effects that might settle this question. Phase-space modifications, resonances, interference, electron spin resonance and non-commutative QED are considered.
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Lech Jakubowski, V. V. P., Marek J. Sadowski Jaroslaw Zebrowski Karol Malinowski Marek Rabinski Horatio Fernandes Carlos Silva Paulo Duarte Marcin Jakubowski. (2012). ISTTOK runaway electrons energies estimation by Cherenkov-type probe with modified AlN radiators. Nukleonika, 57(2), 177–181.
Abstract: Measurements of fast electrons, as performed during recent few years in small tokamaks, demonstrated that<p>detectors based on the Cherenkov effect are very useful tools for such studies. The modernized measuring heads, which<p>were equipped with miniature aluminum-nitride (AlN) radiators, enabled to determine locations and instants of the<p>fast electrons emission and to estimate their energy. A comparison of four measuring channels showed that in ISTTOK<p>the most important role was played by electrons of energy < 90 keV
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