Turing instability in reaction-subdiffusion systems

We determine the conditions for the occurrence of Turing instabilities in activator-inhibitor systems, where one component undergoes subdiffusion and the other normal diffusion. If the subdiffusing species has a nonlinear death rate, then coupling between the nonlinear kinetics and the memory effects of the non-Markovian transport process advances the Turing instability if the inhibitor subdiffuses and delays the Turing instability if the activator subdiffuses. We apply the results of our analysis to the Schnakenberg model, the Gray-Scott model, the Oregonator model of the Belousov-Zhabotinsky reaction, and the Lengyel-Epstein model of the chlorine dioxide-iodine-malonic acid reaction.

Effect of high temperature on Pseudomonas putida NBRI0987 biofilm formation and expression of stress sigma factor RpoS

Pseudomonas is an efficient plant growth-promoting rhizobacteria; however, among the limiting factors for its commercialization, tolerance for high temperature is the most critical one. After screening 2,500 Pseudomnas sp. strains, a high temperature tolerant-strain Pseudomonas putida NBRI0987 was isolated from the drought-exposed rhizosphere of chickpea (Cicer arietinum L. cv. Radhey), which was grown under rain-fed conditions. P. putida NBRI0987 tolerated a temperature of 40 degrees C for < or = 5 days. To the best of our knowledge, this is the first report of a Pseudomnas sp. demonstrating survival estimated by counting viable cells under such a high temperature. P. putida NBRI0987 colony-forming unit (CFU)/ml on day 10 in both the absence and presence of MgSO4 x 7H2O (MgSO4) in combination with glycerol at 40 degrees C were 0.0 and 1.7 x 10(11), respectively. MgSO4 plus glycerol also enhanced the ability of P. putida NBRI0987 to tolerate high temperatures by inducing its ability to form biofilm. However, production of alginate was not critical for biofilm formation. The present study demonstrates overexpression of stress sigma factor sigma(S) (RpoS) when P. putida NBRI0987 is grown under high-temperature stress at 40 degrees C compared with 30 degrees C. We present evidence, albeit indirect, that the adaptation of P. putida NBRI0987 to high temperatures is a complex multilevel regulatory process in which many different genes can be involved.

Acute toxicity levels and ethological responses of Channa striatus to fertilizer industrial wastewater

The present paper deals with the toxicity of fertilizer's industrial wastewater on snake head fish Channa striatus (Bloch) previously named as Ophiocephalus sp., at different concentrations viz., 20, 40, 60, 80 and 100 percent on the behavioural changes and mortality. The exposed fish showed hyperactivity viz., jumping, operculum movement, distance travelling, somersaulting at higher concentration such as 60, 80, and 100 percent within 48 hr. At lower concentrations such as 20 and 40 percent exposed fish showed hyperactivities viz., linear movement and eye movement within 48 hr. The LC50 values of industrial wastewater were also determined viz. 89, 75, 70 and 69 percent at different duration of exposure time i.e. 48, 72, 96 and 120 hr respectively. The obtained data revealed that LC50 value decreased with increase of exposure.

Kinetic equations for reaction-subdiffusion systems: derivation and stability analysis

We derive general kinetic equations for reacting and subdiffusing entities based on a nonlinear continuous time random walk formalism proposed by Vlad and Ross [Phys. Rev. E 66, 061908 (2002)]. Reaction and diffusion processes are separable in a typical reaction-diffusion system, and their combined influence on the evolution of the density of a species is a simple sum. Our derivation shows that this is no longer true for subdiffusive entities undergoing reactions. The strong memory effects in the transport process, i.e., the non-Markovian nature of subdiffusion, results in a nontrivial combination of reactions and spatial dispersal, which we discuss in detail. We carry out a linear stability analysis of the derived reaction-subdiffusion system to understand the effects of memory on pattern formation. We find that the Turing instability persists in the subdiffusive system. However, the memory modifies the Turing threshold and the characteristics of the band of unstable modes close to this threshold.

Assessment of total thrombus load in symptomatic patients with venous thromboembolism

Pulmonary embolism (PE) and Deep vein thrombosis (DVT) are separate but related aspects of the same dynamic process termed as venous thrombembolism (VTE). The existing Asian literature has shown a wide variation in the prevalence of VTE, with very limited data from the Indian subcontinent. Between January 2001 and July 2004, 1,552 patients with clinically suspected lower limb DVT underwent a combined ascending radionuclide venogram and lung perfusion scan for assessment of the total thrombus burden. Of 744 patients with radionuclide venography proven DVT, 294 (40%) had a high probability lung scan. Nearly half of these patients were asymptomatic for pulmonary embolism. The high prevalence of PE in patients with DVT suggests the need for evaluation of thrombus load in the venous as well as pulmonary circulation. A combination radionuclide ascending venography with lung perfusion scan is a useful and reliable single test for this purpose.

Paramagnetic particles and mixing in micro-scale flows

Mixing in microscale flows with rotating chains of paramagnetic particles can be enhanced by adjusting the ratio of viscous to magnetic forces so that chains dynamically break and reform. Lattice Boltzmann (LB) simulations were used to calculate the interaction between the fluid and suspended paramagnetic particles under the influence of a rotating magnetic field. Fluid velocities obtained from the LB simulations are used to solve the advection diffusion equation for massless tracer particles. At relatively high Mason numbers, small chains result in low edge velocities, and hence mixing is slower than at other Mason numbers. At low Mason numbers, long, stable chains form and produce little mixing toward the center of the chains. A peak in mixing rate is observed when chains break and reform. The uniformity of mixing is greater at higher Mason numbers because more small chains result in a larger number of small mixing areas.

Dynamics of rotating paramagnetic particles simulated by lattice Boltzmann and particle dynamics methods

Novel biochemical sensors consisting of rotating chains of microscale paramagnetic particles have been proposed that would enable convenient, sensitive analyte detection. Predicting the dynamics of these particles is required to optimise their design. The results of lattice Boltzmann (LB) and particle dynamics (PD) simulations are reported, where the LB approach provides a verified solution of the complete Navier-Stokes equations, including the hydrodynamic interactions among the particles. On the other hand, the simpler PD approach neglects hydrodynamic interactions, and does not compute the fluid motion. It is shown that macroscopic properties, like the number of aggregated particles, depend only on the drag force and not on the total hydrodynamic force, making PD simulations yield reasonably accurate predictions. Relatively good agreement between the LB and PD simulations, and qualitative agreement with experimental data, are found for the number of aggregated particles as a function of the Mason number. The drag force on a rotating cylinder is significantly different from that on particle chains calculated from both simulations, demonstrating the different dynamics between the two cases. For microscopic quantities like the detailed force distributions on each particle, the complete Navier-Stokes solution, here represented by the LB simulation, is required.

Successful pregnancy in untreated limited Wegener's granulomatosis

A thirty four year old female presented with upper and lower respiratory symptoms in the third trimester of pregnancy. After the delivery of a healthy baby, the symptoms progressed to involve multiple organ systems and eventually a diagnosis of limited Wegener's Granulomatosis (Carrington-Liebow syndrome) was made. The extremely rare combination of WG and pregnancy, especially the onset of disease in late pregnancy is discussed. The successful outcome of pregnancy even without treatment of WG is the highlight of the case.

Prevalence of parenterally transmitted hepatitis viruses in clinically diagnosed cases of hepatitis

Hepatitis B virus (HBV) is the most important causative agent of blood borne hepatitis in humans. Hepatitis D Virus (HDV) infection occurs either as a coinfection or superinfection in HBV carriers. Hepatitis C virus (HCV) is the major cause of transfusion non-A, non-B hepatitis and continues to be a major cause of human liver disease throughout the world. The present study was conducted on 70 clinically diagnosed cases of viral hepatitis to study the prevalence of parenterally transmitted viral hepatitis. The serum samples were tested for HBsAg, HBeAg, IgM anti-HBc, anti-HBe, anti-HCV and anti-HDV using separate ELISA kits. Of the 70 serum samples tested, 28 (40%) were positive for HBsAg out of which 3 (4.28%) were positive for HBeAg also. Five (7.1%) of the HBsAg positive cases tested positive for IgM anti-HBc also. HBsAg alone was found in 17 (24.28%) cases. The prevalence of anti-HCV was 3 (4.28%) in 70 cases. Thus early screening of clinically diagnosed cases of viral hepatitis is essential for establishing diagnosis and treatment to prevent long term sequelae.

Interaction of Ising-Bloch fronts with Dirichlet boundaries

We study the Ising-Bloch bifurcation in two systems, the complex Ginzburg Landau equation (CGLE) and a FitzHugh Nagumo (FN) model in the presence of spatial inhomogeneity introduced by Dirichlet boundary conditions. It is seen that the interaction of fronts with boundaries is similar in both systems, establishing the generality of the Ising-Bloch bifurcation. We derive reduced dynamical equations for the FN model that explain front dynamics close to the boundary. We find that front dynamics in a highly nonadiabatic (slow front) limit is controlled by fixed points of the reduced dynamical equations, that occur close to the boundary.