Master Operators Govern Multifractality in Percolation

Using renormalization group methods we study multifractality in percolation at the instance of noisy random resistor networks. We introduce the concept of master operators. The multifractal moments of the current distribution (which are proportional to the noise cumulants $C_R^{(l)} (x, x^\prime)$ of the resistance between two sites x and $x^\prime$ located on the same cluster) are related to such master operators. The scaling behavior of the multifractal moments is governed exclusively by the master operators, even though a myriad of servant operators is involved in the renormalization procedure. We calculate the family of multifractal exponents ${\psi_l}$ for the scaling behavior of the noise cumulants, $C_R^{(l)} (x, x^\prime) \sim | x - x^\prime |^{\psi_l /\nu}$, where $\nu$ is the correlation length exponent for percolation, to two-loop order.Comment: 6 page

Avaliação genômica de Piper yellow mottle virus da pimenteira do reino (Piper nigrum L.).

Edição dos resumos do 44º Congresso Brasileiro de Fitopatologia, 2011, Bento Gonçalves. Resumo 776

Chaotic dynamics in billiards using Bohm’s quantum mechanics

The dynamics of a particle in square and circular billiards is studied within the framework of Bohm’s quantum mechanics. While conventional quantum mechanics predicts that the system shows no indication of chaotic behavior for these geometries from either the eigenvalue spectra distribution or the structure of the eigenfunctions, we find that in Bohm’s quantum mechanics these systems exhibit both regular and chaotic behavior, depending on the form of the initial wave packet and on the particle’s initial position

Comment on “Inelastic Collapse of a Randomly Forced Particle” by Cornell et al.

A Comment on the Letter by Stephen J. Cornell, Michael R. Swift, and Alan J. Bray, Phys. Rev. Lett. 81, 1142 (1998). The authors of the Letter offer a Reply

Quantum chaos in a double square-well: An approach based on Bohm\u27s view of quantum mechanics

We study the dynamics of a quantum particle in a double square-well potential within a deterministic framework using Bohm’s quantum mechanics. Phase portraits, Fourier spectral analysis, Poincaré sections, and Lyapunov exponents clearly indicate that the particle undergoes periodic, quasiperiodic, and chaotic motions depending on the initial form of the wave packet. We also make a detailed comparison between the predictions of the present approach and those of conventional quantum mechanics for the same problem

Interplay between magnetic anisotropy and interlayer coupling in nanosecond magnetization reversal of spin-valve trilayers

The influence of magnetic anisotropy on nanosecond magnetization reversal in coupled FeNi/Cu/Co trilayers was studied using a photoelectron emission microscope combined with x-ray magnetic circular dicroism. In quasi-isotropic samples the reversal of the soft FeNi layer is determined by domain wall pinning that leads to the formation of small and irregular domains. In samples with uniaxial magnetic anisotropy, the domains are larger and the influence of local interlayer coupling dominates the domain structure and the reversal of the FeNi layer

Weakly Coupled Motion of Individual Layers in Ferromagnetic Resonance

We demonstrate a layer- and time-resolved measurement of ferromagnetic resonance (FMR) in a Ni81Fe19 / Cu / Co93Zr7 trilayer structure. Time-resolved x-ray magnetic circular dichroism has been developed in transmission, with resonant field excitation at a FMR frequency of 2.3 GHz. Small-angle (to 0.2 degree), time-domain magnetization precession could be observed directly, and resolved to individual layers through elemental contrast at Ni, Fe, and Co edges. The phase sensitivity allowed direct measurement of relative phase lags in the precession oscillations of individual elements and layers. A weak ferromagnetic coupling, difficult to ascertain in conventional FMR measurements, is revealed in the phase and amplitude response of individual layers across resonance.Comment: 22 pages, 6 figures submitted to Physical Review

Direct Observation of Massless Domain Wall Dynamics in Nanostripes with Perpendicular Magnetic Anisotropy

Domain wall motion induced by nanosecond current pulses in nanostripes with perpendicular magnetic anisotropy (Pt/Co/AlO$_x$) is shown to exhibit negligible inertia. Time-resolved magnetic microscopy during current pulses reveals that the domain walls start moving, with a constant speed, as soon as the current reaches a constant amplitude, and no or little motion takes place after the end of the pulse. The very low 'mass' of these domain walls is attributed to the combination of their narrow width and high damping parameter $\alpha$. Such a small inertia should allow accurate control of domain wall motion, by tuning the duration and amplitude of the current pulses

Especificidade dos primers PAS-R/PAS3-D e PAS-R/PAS-D na detecção de isolados de Xanthomonas axonopodis pv. passiflorae do estado do Pará.

A mancha bacteriana (Xanthomonas axonopodis pv. passiflorae) destaca-se entre as doenças da cultura do maracujazeiro. Ocorre sob condições de umidade e temperaturas altas e se encontra disseminada no Estado do Pará. O objetivo deste trabalho foi avaliar a especificidade dos pares de primers Pas-R/Pas3-D e Pas-R/Pas-D na detecção de 29 isolados de X. axonopodis pv. passiflorae provenientes de diferentes regiões produtoras de maracujá do Estado. Verificou-se que os primers Pas-R e Pas3-D amplificaram 2 fragmentos de aproximadamente 750pb e 250pb nos isolados de X. axonopodis pv. passiflorae. Enquanto que os primers Pas-R e Pas-D amplificaram 1 fragmento de aproximadamente 1000pb