New Approach of Deterministic Key Pre-distribution Scheme Using Triangle Free Quasi Symmetric Designs

A wireless sensor network (WSN) consists of tiny autonomous sensor nodes with some constraints. There are organizations having moderately necessitates of these kind of networks. So, security become an indispensable concern in WSN, due to potential adversaries. To overcome the security problem, keys are pre-loaded to the nodes before deployment. Among all key distribution schemes, deterministic key pre-distribution scheme (KPS) using combinatorial design is efficient regarding security aspect. In this paper, a deterministic approach, based on combinatorial design, for key assignment before the network deployment has been presented. Here the quasi-symmetric design which is of triangle-free is being used to present the new KPS for sensor networks. Due to this approach each sensor node either will contain a key-chain or will communicate through a key-path. This will improve the resiliency and achieve the sufficient level of security in the network. This design can also be used when a large number of nodes are being deployed in WSN

BRAZILIAN ARCHIVES OF BIOLOGY AND TECHNOLOGY A N I N T E R N A T I O N A L J O U R N A L Hepatic Cytochrome P450 as Biomarkers of Cypermethrin Toxicity in Freshwater Teleost, Channa punctatus (Bloch)

ABSTRACT In this study, Channa punctatus was treated with sub-lethal concentration of cypermethrin (6.

Dynamics of asymmetric intraguild predation with time lags in reproduction and maturation

A three dimensional (3D) stage-structured predator–prey model is proposed and analyzed to study the effect of intraguild predation with harvesting of the adult species. Time lags in reproduction and maturation of the organism are introduced in the system and conditions for local asymptotic stability of steady states of delay differential forms of the ODE model are derived. The length of the delay preserving the stability is also estimated. Moreover, it is shown that the system undergoes a Hopf bifurcation when the time lags cross certain critical values. The stability and direction of the Hopf bifurcations are determined by applying the normal form method and the center manifold theory. Computer simulations have been carried out to illustrate various analytical results

Potential effects of invasive Pterois volitans in coral reefs

The invasion of predatory lionfish (Pterois volitans) represents a major threat to the western Atlantic coral reef ecosystems. The proliferation of venomous, fast reproducing and aggressive P. volitans in coral reefs causes severe declines in the abundance and diversity of reef herbivores. There is also widespread cannibalism amongst P. volitans populations. A mathematical model is proposed to study the effects of predation on the biomass of herbivorous reef fishes by considering two life stages and intraguild predation of P. volitans population with harvesting of adult P. volitans. The system undergoes a supercritical Hopf bifurcation when the invasiveness of P. volitans crosses a certain critical value. It is observed that cannibalism of P. volitans induces stability in the system even with high invasiveness of adult P. volitans. The dynamic instability of the system due to higher invasiveness of P. volitans can be controlled by increasing the rate of harvesting of P. volitans. It is also proven that P. volitans goes extinct when the harvest rate is greater than some critical threshold value. These results indicate that the dynamical behaviour of the model is very sensitive to the harvesting of P. volitans, which in turn is useful in the conservation of reef herbivores

Hepatic Cytochrome P450 as Biomarkers of Cypermethrin Toxicity in Freshwater Teleost, Channa punctatus (Bloch)

In this study, Channa punctatus was treated with sub-lethal concentration of cypermethrin (6.6 µg/L) for 5, 10 and 15 days and its effect on total CYP 450 and the activity of hepatic CYP450 isoforms measured. Total CYP450 content and CYP1A mediated EROD activity was significantly induced (p<0.05) in all three treated groups compared to control whereas only 15 days treated group showed significant induction in CYP2B mediated N,Ndimethylaniline demethylase activity. CYP2E1 mediated aniline hydroxylase activity showed only a marginal increase while there was inhibition of CYP3A4 mediated erythromycin demethylase activity. Liver somatic index (LSI) also showed a marginal increase in all the treated groups. Results showed differential induction of CYP1A, CYP2B, CYP2E1 and inhibition of CYP3A4 isoform due to cypermethrin treatment in C. punctatus. The study clearly showed CYP1A isoform as the most responsive and important biomarker for monitoring the aquatic pollution

Herbivore harvesting and alternative steady states in coral reefs

summary:Coral reefs can undergo relatively rapid changes in the dominant biota, a phenomenon referred to as phase shift. Degradation of coral reefs is often associated with changes in community structure towards a macroalgae-dominated reef ecosystem due to the reduction in herbivory caused by overfishing. We investigate the coral-macroalgal phase shift due to the effects of harvesting of herbivorous reef fish by means of a continuous time model in the food chain. Conditions for local asymptotic stability of steady states are derived. We have shown that under certain conditions the system is uniformly persistent in presence of all the organisms. Moreover, it is shown that the system undergoes a Hopf bifurcation when the carrying capacity of macroalgae crosses certain critical value. Computer simulations have been carried out to illustrate different analytical results