Static- and dynamical-phase transition in multidimensional voting models on continua

A voting model (or a generalization of the Glauber model at zero temperature) on a multidimensional lattice is defined as a system composed of a lattice each site of which is either empty or occupied by a single particle. The reactions of the system are such that two adjacent sites, one empty the other occupied, may evolve to a state where both of these sites are either empty or occupied. The continuum version of this model in a Ddimensional region with boundary is studied, and two general behaviors of such systems are investigated. The stationary behavior of the system, and the dominant way of the relaxation of the system toward its stationary state. Based on the first behavior, the static phase transition (discontinuous changes in the stationary profiles of the system) is studied. Based on the second behavior, the dynamical phase transition (discontinuous changes in the relaxation-times of the system) is studied. It is shown that the static phase transition is induced by the bulk reactions only, while the dynamical phase transition is a result of both bulk reactions and boundary conditions.Comment: 10 pages, LaTeX2

Insecticide Toxicity, Synergism and Resistance in Plutella xylostella (Lepidoptera: Plutellidae)

Plutella xylostella has become particularly notorious for its resistance to various insecticides. The toxicities of abamectin, hexaflumuron and indoxacarb to third instar larvae of the pest were assayed using the leaf-dipping method. The results showed that abamectin and indoxacarb with the lowest LC50 values exhibited stronger toxicity to larvae than hexaflumuron. To determine the synergism of PBO, DEM, DEF and TPP on the toxicity of tested insecticides and demonstrating possible biochemical mechanisms, an abamectin-, a hexaflu-muron- and an indoxacarb-resistant strain of P. xylostella were selected under laboratory conditions. After 10 generations of selection, the selected strains developed 14.21, 7.08, and 32.36-fold higher resistance to these insecticides, respectively. Abamectin resistance in abamectin-selected strain was suppressed with the synergists such as DEM and PBO, suggesting the involvement of monooxygeneses and glutathione S-transferase in the development of resistance in P. xylostella. Treatment with PBO and DEF significantly decreased the toxicity of hexaflumuron in the hexaflumuron-selected strain. Also, in indoxacarb-selected strain, the maximum synergism was occurred using PBO and DEF, followed by DEM and TPP. Hexaflumuron and indoxacarb synergism studies indicated in hexaflumuron resistance, monooxygenases and esterases, and in indoxacarb resistance, monooxygenases, esterases and glutathione S-transferae may be involved in the resistance mechanism

Efficiency of some medicinal plant extracts and an entomopathogenic fungus, Metarhizium anisopliae separately and in combination with proteus® against the large cabbage butterfly, pieris brassicae L.

Pieris brassicae (Lepidoptera: Pieridae) causes great qualitative and quantitative damage to cabbage crops. The present research was conducted to assess the synergistic/antagonistic interactions of Satureja hortensis, Trachyspermum ammi, Ziziphora tenuior, Cuminum cyminum, and Foeniculum vulgare methanolic extracts with Metarhizium anisopliae and Proteus® against P. brassicae pupae under laboratory conditions. The tested methanolic extracts when combined with M. anisopliae and Proteus® possessed synergistic efficacy (except for M. anisopliae + ammi). Probit analysis of extracts revealed S. hortensis as the most effective extract with LC50 value equivalent to 43.49 ppm. Proteus® also exhibited a high efficacy (LC50=48.88). The results support the potential of cumin, fennel, savory and ziziphora methanolic extracts to improve the efficacy of M. anisopliae. Results demonstrated that all tested extracts integrated with Proteus® provide more effective control of P. brassicae than Proteus® alone

Non-Douglas-Kazakov phase transition of two-dimensional generalized Yang-Mills theories

In two-dimensional Yang-Mills and generalized Yang-Mills theories for large gauge groups, there is a dominant representation determining the thermodynamic limit of the system. This representation is characterized by a density the value of which should everywhere be between zero and one. This density itself is determined through a saddle-point analysis. For some values of the parameter space, this density exceeds one in some places. So one should modify it to obtain an acceptable density. This leads to the well-known Douglas-Kazakov phase transition. In generalized Yang-Mills theories, there are also regions in the parameter space where somewhere this density becomes negative. Here too, one should modify the density so that it remains nonnegative. This leads to another phase transition, different from the Douglas-Kazakov one. Here the general structure of this phase transition is studied, and it is shown that the order of this transition is typically three. Using carefully-chosen parameters, however, it is possible to construct models with phase-transition orders not equal to three. A class of these non-typical models are also studied.Comment: 11 pages, accepted for publication in Eur. Phys. J.

Exactly solvable models through the generalized empty interval method: multi-species and more-than-two-site interactions

Multi-species reaction-diffusion systems, with more-than-two-site interaction on a one-dimensional lattice are considered. Necessary and sufficient constraints on the interaction rates are obtained, that guarantee the closedness of the time evolution equation for $E^{\mathbf a}_n(t)$'s, the expectation value of the product of certain linear combination of the number operators on $n$ consecutive sites at time $t$.Comment: 10 pages, LaTe

Slat Cove Unsteadiness Effect of 3D Flow Structures

Previous studies have indicated that 2D, time accurate computations based on a pseudo-laminar zonal model of the slat cove region (within the framework of the Reynolds-Averaged Navier-Stokes equations) are inadequate for predicting the full unsteady dynamics of the slat cove flow field. Even though such computations could capture the large-scale, unsteady vorticity structures in the slat cove region without requiring any external forcing, the simulated vortices were excessively strong and the recirculation zone was unduly energetic in comparison with the PIV measurements for a generic high-lift configuration. To resolve this discrepancy and to help enable physics based predictions of slat aeroacoustics, the present paper is focused on 3D simulations of the slat cove flow over a computational domain of limited spanwise extent. Maintaining the pseudo-laminar approach, current results indicate that accounting for the three-dimensionality of flow fluctuations leads to considerable improvement in the accuracy of the unsteady, nearfield solution. Analysis of simulation data points to the likely significance of turbulent fluctuations near the reattachment region toward the generation of broadband slat noise. The computed acoustic characteristics (in terms of the frequency spectrum and spatial distribution) within short distances from the slat resemble the previously reported, subscale measurements of slat noise

Exactly solvable reaction diffusion models on a Cayley tree

The most general reaction-diffusion model on a Cayley tree with nearest-neighbor interactions is introduced, which can be solved exactly through the empty-interval method. The stationary solutions of such models, as well as their dynamics, are discussed. Concerning the dynamics, the spectrum of the evolution Hamiltonian is found and shown to be discrete, hence there is a finite relaxation time in the evolution of the system towards its stationary state.Comment: 9 pages, 2 figure

Exactly solvable models through the empty interval method

The most general one dimensional reaction-diffusion model with nearest-neighbor interactions, which is exactly-solvable through the empty interval method, has been introduced. Assuming translationally-invariant initial conditions, the probability that $n$ consecutive sites are empty ($E_n$), has been exactly obtained. In the thermodynamic limit, the large-time behavior of the system has also been investigated. Releasing the translational invariance of the initial conditions, the evolution equation for the probability that $n$ consecutive sites, starting from the site $k$, are empty ($E_{k,n}$) is obtained. In the thermodynamic limit, the large time behavior of the system is also considered. Finally, the continuum limit of the model is considered, and the empty-interval probability function is obtained.Comment: 12 pages, LaTeX2

A family of discrete-time exactly-solvable exclusion processes on a one-dimensional lattice

A two-parameter family of discrete-time exactly-solvable exclusion processes on a one-dimensional lattice is introduced, which contains the asymmetric simple exclusion process and the drop-push model as particular cases. The process is rewritten in terms of boundary conditions, and the conditional probabilities are calculated using the Bethe-ansatz. This is the discrete-time version of the continuous-time processes already investigated in [1-3]. The drift- and diffusion-rates of the particles are also calculated for the two-particle sector.Comment: 10 page

Flow-Field Investigation of Gear-Flap Interaction on a Gulfstream Aircraft Model

Off-surface flow measurements of a high-fidelity 18% scale Gulfstream aircraft model in landing configuration with the main landing gear deployed are presented. Particle Image Velocimetry (PIV) and Laser Velocimetry (LV) were used to measure instantaneous velocities in the immediate vicinity of the main landing gear and its wake and near the inboard tip of the flap. These measurements were made during the third entry of a series of tests conducted in the NASA Langley Research Center (LaRC) 14- by 22-Foot Subsonic Tunnel (14 x 22) to obtain a comprehensive set of aeroacoustic measurements consisting of both aerodynamic and acoustic data. The majority of the off-body measurements were obtained at a freestream Mach number of 0.2, angle of attack of 3 degrees, and flap deflection angle of 39 degrees with the landing gear on. A limited amount of data was acquired with the landing gear off. LV was used to measure the velocity field in two planes upstream of the landing gear and to measure two velocity profiles in the landing gear wake. Stereo and 2-D PIV were used to measure the velocity field over a region extending from upstream of the landing gear to downstream of the flap trailing edge. Using a special traverse system installed under the tunnel floor, the velocity field was measured at 92 locations to obtain a comprehensive picture of the pertinent flow features and characteristics. The results clearly show distinct structures in the wake that can be associated with specific components on the landing gear and give insight into how the wake is entrained by the vortex at the inboard tip of the flap