14,032 research outputs found
Counterions at charge-modulated substrates
We consider counterions in the presence of a single planar surface with a
spatially inhomogeneous charge distribution using Monte-Carlo simulations and
strong-coupling theory. For high surface charges, multivalent counterions, or
pronounced substrate charge modulation the counterions are laterally correlated
with the surface charges and their density profile deviates strongly from the
limit of a smeared-out substrate charge distribution, in particular exhibiting
a much increased laterally averaged density at the surface.Comment: 7 page
Micro-bias and macro-performance
We use agent-based modeling to investigate the effect of conservatism and
partisanship on the efficiency with which large populations solve the density
classification task--a paradigmatic problem for information aggregation and
consensus building. We find that conservative agents enhance the populations'
ability to efficiently solve the density classification task despite large
levels of noise in the system. In contrast, we find that the presence of even a
small fraction of partisans holding the minority position will result in
deadlock or a consensus on an incorrect answer. Our results provide a possible
explanation for the emergence of conservatism and suggest that even low levels
of partisanship can lead to significant social costs.Comment: 11 pages, 5 figure
Wigner-Crystal Formulation of Strong-Coupling Theory for Counter-ions Near Planar Charged Interfaces
We present a new analytical approach to the strong electrostatic coupling
regime (SC), that can be achieved equivalently at low temperatures, high
charges, low dielectric permittivity etc. Two geometries are analyzed in
detail: one charged wall first, and then, two parallel walls at small
distances, that can be likely or oppositely charged. In all cases, one type of
mobile counter-ions only is present, and ensures electroneutrality (salt free
case). The method is based on a systematic expansion around the ground state
formed by the two-dimensional Wigner crystal(s) of counter-ions at the
plate(s). The leading SC order stems from a single-particle theory, and
coincides with the virial SC approach that has been much studied in the last 10
years. The first correction has the functional form of the virial SC
prediction, but the prefactor is different. The present theory is free of
divergences and the obtained results, both for symmetrically and asymmetrically
charged plates, are in excellent agreement with available data of Monte-Carlo
simulations under strong and intermediate Coulombic couplings. All results
obtained represent relevant improvements over the virial SC estimates. The
present SC theory starting from the Wigner crystal and therefore coined Wigner
SC, sheds light on anomalous phenomena like the counter-ion mediated
like-charge attraction, and the opposite-charge repulsion
Universal reduction of pressure between charged surfaces by long-wavelength surface charge modulation
We predict theoretically that long-wavelength surface charge modulations
universally reduce the pressure between the charged surfaces with counterions
compared with the case of uniformly charged surfaces with the same average
surface charge density. The physical origin of this effect is the fact that
surface charge modulations always lead to enhanced counterion localization near
the surfaces, and hence, fewer charges at the midplane. We confirm the last
prediction with Monte Carlo simulations.Comment: 8 pages 1 figure, Europhys. Lett., in pres
Irrigated rice area estimation using remote sensing techniques: Project's proposal and preliminary results
The development of a methodology for annual estimates of irrigated rice crop in the State of Rio Grande do Sul, Brazil, using remote sensing techniques is proposed. The project involves interpretation, digital analysis, and sampling techniques of LANDSAT imagery. Results are discussed from a preliminary phase for identifying and evaluating irrigated rice crop areas in four counties of the State, for the crop year 1982/1983. This first phase involved just visual interpretation techniques of MSS/LANDSAT images
Dinâmica da matéria orgânica na recuperação de clareiras da floresta amazônica.
O objetivo deste trabalho foi avaliar a dinâmica da matéria orgânica e da biomassa microbiana em áreas de reflorestamento com 0, 1, 2, 4 e 10 anos de idade realizados na província petrolífera do rio Urucu, localizada no município de Coari, região central do Estado do Amazonas
Production of exotic charmonium in interactions at hadronic colliders
In this paper we investigate the Exotic Charmonium (EC) production in interactions present in proton-proton, proton-nucleus and
nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC) energies as
well as for the proposed energies of the Future Circular Collider (FCC). Our
results demonstrate that the experimental study of these processes is feasible
and can be used to constrain the theoretical decay widths and shed some light
on the configuration of the considered multiquark states.Comment: 7 pages, 2 figures, 3 tables. v2: Revised version published in
Physical Review
- …