Status of heavy metal pollution in the Lunawa lagoon

Distribution offive types of heavy metals in the Lunawa Lagoon (Colombo District) was investigatedfrom April to June 2006. Water and bottom sludge samples were obtained at fortnight intervals fromnine sampling stations of the lagoon including three drains (Northern, Eastern and Uyana). Watersamples were preserved by adding Cone. HNOJ (Analytical Grade) to adjust the pH to < 2 andbottom sludge samples were treated by 'Wet Ashing Method' before analysis. Concentrations of Cu, Zn, Pb, Cd and Cr were determined by Atomic Absorption Spectrophotometry. Cu, Zn, Pb and Crwere found both in water and bottom sludge samples of all sites, while Cd was not recorded from anyof the sites. Significantly higher concentrations of heavy metals (Mean ± SEM: Cu 120.75 ug/g ±8.43; Zn 570.98 ug/g ± 11.53; Pb 204.37 flg/g ± 7.50; Cr 52.50 ug/g ± 4.36: One- way ANOYA;P<O.OI) were found in bottom sludge of the Southern lagoon than the Northern lagoon and the threedrains. This is possible because the Southern lagoon is situated away from the sea outfall and theintensity offlushing by sea water is relatively less in this sector. Heavy metal concentrations in waterin different sites did not differ significantly, however, water in the Southern lagoon contained a relativelyhigher concentrations ofCu (0.049 ppm ± 0.002) and Pb (0.096 ppm ± 0.006) while the highest levelof Cr (0.035 ppm ± 0.020) and Zn (0.151 ppm ± 0.017) were recorded from the Eastern Drain.Bottom sludge contained significantly higher concentrations of all heavy metals than in water (P<O.OOI)indicating accumulation of metal ions in the sludge for a long period of time. Lagoon water could havebeen contaminated by point sources (such as Automotive Workshops and Textile Factories) and nonpointsources (such as Service Stations along the Galle Road) of heavy metal pollutants

BEHAVIOUR OF JUVENILE ASIAN ELEPHANTS IN Panicum maximum DOMINA TED GRASSLANDS IN THE UDA WALA WA NATIONAL PARK.

Guinea grass (Panicum maximum) dominated grasslands, a major habitat typein the Udawalawa National Park, is frequently occupied by wild elephants.Behaviour of juvenile elephants (4-6 years old) inhabiting the habitat wasstudied from April 2004 to March 2005. Focal animal sampling was employedto quantify behaviour and total time of observation was 3100 minutes.The activity budget of the juveniles comprised of ten behaviour patterns;feeding (44%), resting (24%), locomotion (19%), play (5%), comfort (5%),drinking, social, exploratory, agonistic and anxious. Maximum feeding (55%)and minimum resting (13%) were recorded during late afternoons (1500-1800hrs) whilst maximum resting (37%) and minimum feeding (29%) wererecorded during late mornings (0900-1200 hrs). Locomotion and otherbehaviour patterns did not significantly vary with time. Time spent on feedingwas higher in wet months (47%) than in dry months (39%). Resting wasrelatively higher in dry period (27%) than in wet (21 %). P. maximum was themajor food type consumed throughout the year while they fed on native grassesand herbs to a lesser extent (21-29%). Significant correlations between ambienttemperature and time spent on feeding (r= -0.716) and resting (r = +0.751)were evident.The Department of Wildlife Conservation and the Born Free Foundation, UKare acknowledged.

Allotransplanted Neurons Used to Repair Peripheral Nerve Injury Do Not Elicit Overt Immunogenicity

A major problem hindering the development of autograft alternatives for repairing peripheral nerve injuries is immunogenicity. We have previously shown successful regeneration in transected rat sciatic nerves using conduits filled with allogeneic dorsal root ganglion (DRG) cells without any immunosuppression. In this study, we re-examined the immunogenicity of our DRG neuron implanted conduits as a potential strategy to overcome transplant rejection. A biodegradable NeuraGen® tube was infused with pure DRG neurons or Schwann cells cultured from a rat strain differing from the host rats and used to repair 8 mm gaps in the sciatic nerve. We observed enhanced regeneration with allogeneic cells compared to empty conduits 16 weeks post-surgery, but morphological analyses suggest recovery comparable to the healthy nerves was not achieved. The degree of regeneration was indistinguishable between DRG and Schwann cell allografts although immunogenicity assessments revealed substantially increased presence of Interferon gamma (IFN-γ) in Schwann cell allografts compared to the DRG allografts by two weeks post-surgery. Macrophage infiltration of the regenerated nerve graft in the DRG group 16 weeks post-surgery was below the level of the empty conduit (0.56 fold change from NG; p<0.05) while the Schwann cell group revealed significantly higher counts (1.29 fold change from NG; p<0.001). Major histocompatibility complex I (MHC I) molecules were present in significantly increased levels in the DRG and Schwann cell allograft groups compared to the hollow NG conduit and the Sham healthy nerve. Our results confirmed previous studies that have reported Schwann cells as being immunogenic, likely due to MHC I expression. Nerve gap injuries are difficult to repair; our data suggest that DRG neurons are superior medium to implant inside conduit tubes due to reduced immunogenicity and represent a potential treatment strategy that could be preferable to the current gold standard of autologous nerve transplant

Review on computational methods for Lyapunov functions

Lyapunov functions are an essential tool in the stability analysis of dynamical systems, both in theory and applications. They provide sufficient conditions for the stability of equilibria or more general invariant sets, as well as for their basin of attraction. The necessity, i.e. the existence of Lyapunov functions, has been studied in converse theorems, however, they do not provide a general method to compute them. Because of their importance in stability analysis, numerous computational construction methods have been developed within the Engineering, Informatics, and Mathematics community. They cover different types of systems such as ordinary differential equations, switched systems, non-smooth systems, discrete-time systems etc., and employ di_erent methods such as series expansion, linear programming, linear matrix inequalities, collocation methods, algebraic methods, set-theoretic methods, and many others. This review brings these different methods together. First, the different types of systems, where Lyapunov functions are used, are briefly discussed. In the main part, the computational methods are presented, ordered by the type of method used to construct a Lyapunov function

NECESSARY AND SUFFICIENT CONDITIONS FOR NONINTERACTING CONTROL WITH STABILITY FOR A CLASS OF NONLINEAR SYSTEMS

In this paper we address the problem of noninteracting control with stability for a class of nonlinear square systems for which noninteraction can be achieved (without stability) by means of invertible static state-feedback. The use of both static state feedback and dynamic state-feedback is investigated. We prove that in both cases the asymptotic stabilizability of certain subsystems is necessary to achieve noninteraction and stability. We use this and some recent results to state a complete set of necessary and sufficient conditions in order to solve the problem

Noninteracting control with stability for a class of nonlinear systems

In this paper nonintearcting control with stability in a global coordinatee-free settin

Stabilization of globally noninteractive nonlinear systems via dynamic state-feedback

In this paper noninteracting control with stability in a global coordinate-free settin