Diffusion-limited reaction for the one-dimensional trap system

We have previously discussed the one-dimensional multitrap system of finite range and found the somewhat unexpected result that the larger is the number of imperfect traps the higher is the transmission through them. We discuss in this work the effect of a small number of such traps arrayed along either a constant or a variable finite spatial section. It is shown that under specific conditions, to be described in the following, the remarked high transmission may be obtained for this case also. Thus, compared to the theoretical large number of traps case these results may be experimentally applied to real phenomenaComment: 18 pages, 8 PS Figures; 3 former figures were removed, a new section added and the representation is improve

Numerical study of breathers in a bent chain of oscillators with long-range interaction

Most of the studies of breathers in networks of oscillators are limited to nextneighbour interaction. However, long-range interaction becomes critical when the geometry of the chain is taken into account, as the distance between oscillators and, therefore, the coupling, depends on the shape of the system. In this paper we analyse the existence and stability of breathers, i.e. localized oscillations in a simple model for a bent chain of oscillators with long-range interaction.European Union HPRN–CT–1999–0016

Adsorption of Reactive Particles on a Random Catalytic Chain: An Exact Solution

We study equilibrium properties of a catalytically-activated annihilation $A + A \to 0$ reaction taking place on a one-dimensional chain of length $N$ ($N \to \infty$) in which some segments (placed at random, with mean concentration $p$) possess special, catalytic properties. Annihilation reaction takes place, as soon as any two $A$ particles land onto two vacant sites at the extremities of the catalytic segment, or when any $A$ particle lands onto a vacant site on a catalytic segment while the site at the other extremity of this segment is already occupied by another $A$ particle. Non-catalytic segments are inert with respect to reaction and here two adsorbed $A$ particles harmlessly coexist. For both "annealed" and "quenched" disorder in placement of the catalytic segments, we calculate exactly the disorder-average pressure per site. Explicit asymptotic formulae for the particle mean density and the compressibility are also presented.Comment: AMSTeX, 27 pages + 4 figure

Screening of Dirac flavor structure in the seesaw and neutrino mixing

We consider the mechanism of screening of the Dirac flavor structure in the context of the double seesaw mechanism. As a consequence of screening, the structure of the light neutrino mass matrix, m_\nu, is determined essentially by the structure of the (Majorana) mass matrix, M_S, of new super-heavy (Planck scale) neutral fermions S. We calculate effects of the renormalization group running in order to investigate the stability of the screening mechanism with respect to radiative corrections. We find that screening is stable in the supersymmetric case, whereas in the standard model it is unstable for certain structures of M_S. The screening mechanism allows us to reconcile the (approximate) quark-lepton symmetry and the strong difference of the mixing patterns in the quark and lepton sectors. It opens new possibilities to explain a quasi-degenerate neutrino mass spectrum, special ``neutrino'' symmetries and quark-lepton complementarity. Screening can emerge from certain flavor symmetries or Grand Unification.Comment: 27 pages, 3 figures; references added, discussion of the E6 model modifie

Kink propagation in a two-dimensional curved Josephson junction

We consider the propagation of sine-Gordon kinks in a planar curved strip as a model of nonlinear wave propagation in curved wave guides. The homogeneous Neumann transverse boundary conditions, in the curvilinear coordinates, allow to assume a homogeneous kink solution. Using a simple collective variable approach based on the kink coordinate, we show that curved regions act as potential barriers for the wave and determine the threshold velocity for the kink to cross. The analysis is confirmed by numerical solution of the 2D sine-Gordon equation.Comment: 8 pages, 4 figures (2 in color

Robust stationary entanglement of two coupled qubits in independent environments

The dissipative dynamics of two interacting qubits coupled to independent reservoirs at nonzero temperatures is investigated, paying special attention to the entanglement evolution. The counter-rotating terms in the qubit-qubit interaction give rise to stationary entanglement, traceable back to the ground state structure. The robustness of this entanglement against thermal noise is thoroughly analyzed, establishing that it can be detected at reasonable experimental temperatures. Some effects linked to a possible reservoir asymmetry are brought to light.Comment: 8 pages, 6 figures; version accepted for publication on Eur. Phys. J.

Use of cultivar resistance and crop rotation with Bacillus subtilis for clubroot control in canola

Non-Peer ReviewedThis study was conducted to assess additional strategies potentially complimentary to cultivar resistance or biocontrol in control of clubroot. New granular Bacillus subtilis formulations and a seed dressing method were developed to facilitate biofungicide delivery in field trials. The granular formulations were applied in furrow during seeding at 50 kg/ha to a clubroot resistant (CR) and susceptible (CS) canola cultivar, respectively, in three field trials. The seed dressing applied approximately 1×105 to 5×106 cfu/seed doses of the biocontrol agent, and was evaluated on the CS cultivar seeded to different crop-rotation scenarios where the plots had a 1-year, 3-year, or 11-year break from last canola crop. Clubroot disease pressure was high at all trial sites with disease severity indexes (DSI) ranging from 69% to 98% on the CS cultivar. None of the granular formulations reduced clubroot substantially, whereas the CR cultivar showed a high effect, reducing DSI to below 15% and doubling the yield over that of CS cultivar. Plots of varying rotation showed a pattern of clubroot pathogen pressure, with those of 1-year break from canola being the highest. The DSI for all rotational scenarios was high, reaching 100% in short-rotation plots. Biofungicide seed dressing did not reduce DSI, but longer crop rotation often reduced gall size slightly, showed much milder above-ground damage, and increased the yield significantly relative to short rotation in two separate trials. Even a 3-year break from canola was highly beneficial, with the yield doubled as opposed to that with only 1-year break from canola

Entangled light in transition through the generation threshold

We investigate continuous variable entangling resources on the base of two-mode squeezing for all operational regimes of a nondegenerate optical parametric oscillator with allowance for quantum noise of arbitrary level. The results for the quadrature variances of a pair of generated modes are obtained by using the exact steady-state solution of Fokker-Planck equation for the complex P-quasiprobability distribution function. We find a simple expression for the squeezed variances in the near-threshold range and conclude that the maximal two-mode squeezing reaches 50% relative to the level of vacuum fluctuations and is achieved at the pump field intensity close to the generation threshold. The distinction between the degree of two-mode squeezing for monostable and bistable operational regimes is cleared up.Comment: 7 pages, 4 figures; Content changed: more details added to the discussion. To be published in Phys. Rev.

Regular and stochastic behavior of Parkinsonian pathological tremor signals

Regular and stochastic behavior in the time series of Parkinsonian pathological tremor velocity is studied on the basis of the statistical theory of discrete non-Markov stochastic processes and flicker-noise spectroscopy. We have developed a new method of analyzing and diagnosing Parkinson's disease (PD) by taking into consideration discreteness, fluctuations, long- and short-range correlations, regular and stochastic behavior, Markov and non-Markov effects and dynamic alternation of relaxation modes in the initial time signals. The spectrum of the statistical non-Markovity parameter reflects Markovity and non-Markovity in the initial time series of tremor. The relaxation and kinetic parameters used in the method allow us to estimate the relaxation scales of diverse scenarios of the time signals produced by the patient in various dynamic states. The local time behavior of the initial time correlation function and the first point of the non-Markovity parameter give detailed information about the variation of pathological tremor in the local regions of the time series. The obtained results can be used to find the most effective method of reducing or suppressing pathological tremor in each individual case of a PD patient. Generally, the method allows one to assess the efficacy of the medical treatment for a group of PD patients.Comment: 39 pages, 10 figures, 1 table Physica A, in pres

Theory of coherent acoustic phonons in InGaN/GaN multi-quantum wells

A microscopic theory for the generation and propagation of coherent LA phonons in pseudomorphically strained wurzite (0001) InGaN/GaN multi-quantum well (MQW) p-i-n diodes is presented. The generation of coherent LA phonons is driven by photoexcitation of electron-hole pairs by an ultrafast Gaussian pump laser and is treated theoretically using the density matrix formalism. We use realistic wurzite bandstructures taking valence-band mixing and strain-induced piezo- electric fields into account. In addition, the many-body Coulomb ineraction is treated in the screened time-dependent Hartree-Fock approximation. We find that under typical experimental conditions, our microscopic theory can be simplified and mapped onto a loaded string problem which can be easily solved.Comment: 20 pages, 17 figure