Exact Solution of a Reaction-Diffusion Model with Particle Number Conservation

We analytically investigate a 1d branching-coalescing model with reflecting boundaries in a canonical ensemble where the total number of particles on the chain is conserved. Exact analytical calculations show that the model has two different phases which are separated by a second-order phase transition. The thermodynamic behavior of the canonical partition function of the model has been calculated exactly in each phase. Density profiles of particles have also been obtained explicitly. It is shown that the exponential part of the density profiles decay on three different length scales which depend on total density of particles.Comment: 7 pages, REVTEX4, Contents updated and new references added, to appear in Physical Review

Working memory replay prioritizes weakly attended events

One view of working memory posits that maintaining a series of events requires their sequential and equal mnemonic replay. Another view is that the content of working memory maintenance is prioritized by attention. We decoded the dynamics for retaining a sequence of items using magnetoencephalography, wherein participants encoded sequences of three stimuli depicting a face, a manufactured object, or a natural item and maintained them in working memory for 5000 ms. Memory for sequence position and stimulus details were probed at the end of the maintenance period. Decoding of brain activity revealed that one of the three stimuli dominated maintenance independent of its sequence position or category; and memory was enhanced for the selectively replayed stimulus. Analysis of event-related responses during the encoding of the sequence showed that the selectively replayed stimuli were determined by the degree of attention at encoding. The selectively replayed stimuli had the weakest initial encoding indexed by weaker visual attention signals at encoding. These findings do not rule out sequential mnemonic replay but reveal that attention influences the content of working memory maintenance by prioritizing replay of weakly encoded events. We propose that the prioritization of weakly encoded stimuli protects them from interference during the maintenance period, whereas the more strongly encoded stimuli can be retrieved from long-term memory at the end of the delay period

Efficient light coupling into a photonic crystal waveguide with flatband slow mode

We design an efficient coupler to transmit light from a strip waveguide into the flatband slow mode of a photonic crystal waveguide with ring-shaped holes. The coupler is a section of a photonic crystal waveguide with a higher group velocity, obtained by different ring dimensions. We demonstrate coupling efficiency in excess of 95% over the 8 nm wavelength range where the photonic crystal waveguide exhibits a quasi constant group velocity vg = c/37. An analysis based on the small Fabry-P\'erot resonances in the simulated transmission spectra is introduced and used for studying the effect of the coupler length and for evaluating the coupling efficiency in different parts of the coupler. The mode conversion efficiency within the coupler is more than 99.7% over the wavelength range of interest. The parasitic reflectance in the coupler, which depends on the propagation constant mismatch between the slow mode and the coupler mode, is lower than 0.6% within this wavelength range.Comment: 11 pages, 7 figures, submitted to Photonics and Nanostructures - Fundamentals and Application

Operator Method for Nonperturbative Calculation of the Thermodynamic Values in Quantum Statistics. Diatomic Molecular Gas

Operator method and cumulant expansion are used for nonperturbative calculation of the partition function and the free energy in quantum statistics. It is shown for Boltzmann diatomic molecular gas with some model intermolecular potentials that the zeroth order approximation of the proposed method interpolates the thermodynamic values with rather good accuracy in the entire range of both the Hamiltonian parameters and temperature. The systematic procedure for calculation of the corrections to the zeroth order approximation is also considered.Comment: 22 pages, 7 Postscript figures, accepted for publication in Journal of Physics

Molecular Diagnosis of Iris Yellow Spot Virus (IYSV) on Onion in Iran

Viral symptoms indicative of Iris yellow spot virus (IYSV) were observed on onion in several fields near Chenaran in Khorasan Razavi Province. Mechanical inoculation of herbaceous hosts with onion sap extracts from symptomatic plants showed similar symptoms to those described for IYSV. The mechanically transmitted virus reacted only with antisera specific to IYSV in DAS-ELISA but not with antisera specific to seven other tospoviruses. In RT-PCR, a DNA fragment approximately 822 bp in size was amplified from infected Nicotiana benthamiana by using primers specific to the nucleocapsid (N) gene of IYSV. After cloning and sequencing, the deduced N protein sequence of two isolates (GenBank accession no. HQ148173 and HQ148174) showed 98% amino acid identity with a Sri Lankan isolate, 96% with a Dutch isolate and 92% with a Brazilian isolate. To our knowledge, this is the first molecular characterization of IYSV in Ira

Microscopic structure of travelling wave solutions in a class of stochastic interacting particle systems

We obtain exact travelling wave solutions for three families of stochastic one-dimensional nonequilibrium lattice models with open boundaries. These solutions describe the diffusive motion and microscopic structure of (i) of shocks in the partially asymmetric exclusion process with open boundaries, (ii) of a lattice Fisher wave in a reaction-diffusion system, and (iii) of a domain wall in non-equilibrium Glauber-Kawasaki dynamics with magnetization current. For each of these systems we define a microscopic shock position and calculate the exact hopping rates of the travelling wave in terms of the transition rates of the microscopic model. In the steady state a reversal of the bias of the travelling wave marks a first-order non-equilibrium phase transition, analogous to the Zel'dovich theory of kinetics of first-order transitions. The stationary distributions of the exclusion process with $n$ shocks can be described in terms of $n$-dimensional representations of matrix product states.Comment: 27 page

Effect of a multivitamin complex and probiotic blend in drinking water before and after vaccination on performance traits, blood biochemistry and humoral immune response of broilers

This study was conducted in order to investigate the effects of a multivitamin complex and probiotic blend in drinking water before and after vaccination on growth performance, carcass traits, blood biochemical parameters and humoral immune response of broiler chickens. A total of 150 one day-old male broiler chicks (Ross 308) were randomly allocated to five treatment groups, with three replicates (10 birds per replicate) in a completely randomized design. Experimental treatments consisted of: 1) a basal diet and drinking water without any additives as control (C); 2) C + drinking water + multivitamin complex from 2 days before vaccination until 3 days after vaccination; 3) C + drinking water + multivitamin complex for 3 days after vaccination; 4) C + drinking water + probiotic blend from 2 days before vaccination until 3 days after vaccination; and 5) C + drinking water + probiotic blend for 3 days after vaccination. In the whole experimental period, feed intake, body and thigh weight and abdominal fat were significantly affected (P<0.05) by dietary treatments. On the contrary, no significant effect was observed on carcass characteristics, feed conversion ratio, blood parameters, antibody production against SRBC and IgG. The titer of IgM was higher in treatment (2) than other treatments at 28 d of age (P<0.05). In conclusion, a multivitamin complex supplied in drinking water for 2 days before vaccination till 3 days after vaccination is enable to improve broiler performance and immunity