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

Repelling Random Walkers in a Diffusion-Coalescence System

We have shown that the steady state probability distribution function of a diffusion-coalescence system on a one-dimensional lattice of length L with reflecting boundaries can be written in terms of a superposition of double shock structures which perform biased random walks on the lattice while repelling each other. The shocks can enter into the system and leave it from the boundaries. Depending on the microscopic reaction rates, the system is known to have two different phases. We have found that the mean distance between the shock positions is of order L in one phase while it is of order 1 in the other phase.Comment: 5 pages, 1 EPS figure, Accepted for publication in PRE (2008

First Order Phase Transition in a Reaction-Diffusion Model With Open Boundary: The Yang-Lee Theory Approach

A coagulation-decoagulation model is introduced on a chain of length L with open boundary. The model consists of one species of particles which diffuse, coagulate and decoagulate preferentially in the leftward direction. They are also injected and extracted from the left boundary with different rates. We will show that on a specific plane in the space of parameters, the steady state weights can be calculated exactly using a matrix product method. The model exhibits a first-order phase transition between a low-density and a high-density phase. The density profile of the particles in each phase is obtained both analytically and using the Monte Carlo Simulation. The two-point density-density correlation function in each phase has also been calculated. By applying the Yang-Lee theory we can predict the same phase diagram for the model. This model is further evidence for the applicability of the Yang-Lee theory in the non-equilibrium statistical mechanics context.Comment: 10 Pages, 3 Figures, To appear in Journal of Physics A: Mathematical and Genera

The Study of Shocks in Three-States Driven-Diffusive Systems: A Matrix Product Approach

We study the shock structures in three-states one-dimensional driven-diffusive systems with nearest neighbors interactions using a matrix product formalism. We consider the cases in which the stationary probability distribution function of the system can be written in terms of superposition of product shock measures. We show that only three families of three-states systems have this property. In each case the shock performs a random walk provided that some constraints are fulfilled. We calculate the diffusion coefficient and drift velocity of shock for each family.Comment: 15 pages, Accepted for publication in Journal of Statistical Mechanics: Theory and Experiment (JSTAT

Epidemiology and short-term mortality in traumatic patients admitted to Shariati Hospital in Iran between 2012 and 2013

Purpose Trauma is an inevitable part of the health burden in every country. Both the preventive and rehabilitative aspects of traumatic injuries are expensive. Since most of the injuries happen in low- and middle-income developing countries, a judicious allocation of the limited resources to the most cost-efficient strategies is necessary. The present study was designed to report the causes of trauma, injured body regions, trauma severity scores and the one year survival rate of a randomly selected sample of trauma patients in a major referral hospital in Tehran, Iran. Methods We chose and analyzed a random subgroup of traumatic patients admitted during the one-year period of May 2012 to May 2013 to Shariati Hospital, a major University Teaching Hospital in Tehran, Iran. Patients who stayed at the hospital for less than 24 h were excluded. In total, 73 traumatic patients were registered. The mean age was (40.19 ± 20.34) years and 67.1 of them were male. Results In general, the most common cause of injury was falls (47.9), followed by road traffic crashes (RTCs, 40.8). Assault and exposure to inanimate mechanical forces each were only associated with 5.6 of all injuries. The only cause of injury in ages of more than 65 years was fall. The most common cause of injury in ages between 15 and 45 years was RTCs. During the study, two deaths occurred: one was at ICU and the other was at home. The most commonly injured body region was the head (23.8), followed by the elbow and forearm (19), hip and thigh (15.9), and multiple body regions (14.3). The mean abbreviated injury score was 2.23 ± 1.02; injury severity index was 7.26 ± 7.06; and revised trauma score was 7.84, calculated for 38 patients. Conclusion Prevention strategy of traumatic injury should focus on falls and RTCs, which are respectively the most common cause of trauma in older aged people and young males. © 2015 Production and hosting by Elsevier B.V

Relaxation time in a non-conserving driven-diffusive system with parallel dynamics

We introduce a two-state non-conserving driven-diffusive system in one-dimension under a discrete-time updating scheme. We show that the steady-state of the system can be obtained using a matrix product approach. On the other hand, the steady-state of the system can be expressed in terms of a linear superposition Bernoulli shock measures with random walk dynamics. The dynamics of a shock position is studied in detail. The spectrum of the transfer matrix and the relaxation times to the steady-state have also been studied in the large-system-size limit.Comment: 10 page

Microbial and biochemical characteristics of fermented fish sausage from common carp (Cyprinus carpio) mince by application of Pediococcus pentasaceus at different incubation temperatures

Fermented sausage is a favorite kind of meat-product that has allocated great proportions of meat consumption in the world. For the first time in Iran in this study the production of Fermented sausage from minced meat of common carp was assessed by means of lactic acid bacteria at different incubating temperatures as 15, 25, and 35˚C. To prepare the fish sausage, common carp mince was grounded and mixed with NaCl (3%), glucose (3%) and lactic acid bacteria at 5 log CFU/g and afterward were incubated for 48 h. During the incubation of fish sausage, microbiological tests, moisture and protein content, and TVB-N were measured. According to the results, the higher temperature of 35˚C stimulated the rapid growth of lactic acid bacteria, resulting in a rapid decline in pH, and consequently suppressed the growth of pseudomonas, Micrococcaceae and Enterobacteriacea

Quality characteristics of common carp (Cyprinus carpio) surimi and kamaboko and the role of sarcaoplasmic proteins

This study was carried out to determine the characteristics of common carp surimi. In Australia, common carp (Cyprinus carpio) is an environmental pest, strongly coloured (dark-muscle fish), large (2-3 kg), low cost (AUD 2.5/kg) and not highly valued as it is every where else. Surimi could add value to carp, but the colour would have to be modified as surimi manufacturers prefer white coloured flesh. So, firstly the efficiency of Hydrogen peroxide (H2O2; 1-3% v/v) solution at alkaline side of pH (7.0-11.5) on whitening of light fillets of common carp was examined. The whiteness (L*-3b*) of surimi produced from treated (3% H2O2, pH 8.2) common carp light fillets was significantly (p less than 0.05) greater than that of threadfin bream surimi and was not significantly different to that of Alaska pollock. Based on a temperature sweep test, a similar pattern in G of tested surimi wa s observed which started at ca. 47?C and was completed at ca. 73-74?C. However, threadfin bream kamaboko showed better texture profile characteristics (hardness and gel strength) than that of the other kamaboko tested. To improve the quality of common carp surimi and kamaboko, alternative methods were applied such as modified conventional method (MCM), alkaline-aided method (AAM) and pH modified method (PMM) and the resultant surimi and kamaboko were compared with those produced by the traditional method (TM). In MCM each washing cycle was followed by a centrifugation step for a more effective dewatering and removal of sarcoplasmic proteins (Sp-P). Kamaboko prepared from MCM was whiter and had significantly (p less than 0.05) improved textural characteristics (hardness and gel strength) than that from TM, AAM and PMM. Furthermore, SEM of surimi and kamaboko showed higher number of polygonal structure/mm2 in the gel matrix of MCM kamaboko, as a result of more cross-linking of the myofibrillar proteins, than that recorded for TM, AAM and PMM samples tested. Finally, this study examined the effect of adding common carp sarcoplasmic proteins (Sp-P) on the gel characteristics of threadfin bream surimi and kamaboko. Based on the temperature sweep test, the depths of the valley in the G thermograph of the gels decreased as the concentration of added Sp-P increased from 5% to 35%. Storage modulus (G) of the gels showed greater elasticity in the samples with added Sp-P compared with the control samples without added Sp-P. Furthermore, the breaking force and breaking distance and consequently gel strength of the resultant kamaboko were improved, significantly (p less than 0.05) with added Sp-P. Thus, added Sp-P did not interfere with the gelling of myofibrillar proteins during sol-gel transition phase and was associated with textural quality enhancement for the resultant kamaboko. However, the addition of freeze-dried Sp-P from the dark muscle of the carp decreased the whiteness of the resultant surimi. Furthermore, the gel strength could not be associated with either the number of polygonal structures/mm2 or the area of the polygonal structures