INTRACELLULAR OSMOREGULATION IN THE ESTUARINE MOLLUSC VILLORITA CYPRINOIDES VAR. COCHINENSIS (Mollusca: Bivalvia) Hanley

The present investigation is dedicated to understanding various mechanisms of salinity tolerance in the estuarine clam V. cyprinoides var. cochinensis. Even though V. cyprinoids var. cochinensis and V. cyprinoides are found to coexist in the same area, V. cyprinoids is reported to tolerate higher salinities than variety cochinenesis. Variations in the salinity of sea water may affect the aquatic organisms through specific gravity control and variations in osmotic pressure. The specific gravity of most soft tissues is close to that of normal seawater. Many bottom living forms, both attached and motile, have very high specific gravities eg.villorita cyprinoids. Villorita spp. Occurs abundantly in the reaches of the estuary and backwaters of Kerala. In both marine and estuarine forms, it is observed that mantle employs a lesser quantity of amino acids compared to adductor and foot. The regulation of cell volume is not carried out equally in all types of tissues. The capability of salinity tolerance is an aggregate of both the capabilities of extra cellular anisosmotic and intracellular isosmotic regulations in osmoconforming animals. The ultimate aim of water regulation is to regulate the cell volume.T here are slight changes occur in cell volume even in osmoregulators. These studies can also help in revealing the changes brought about in the cellular organelles like lysosomes, which were found to have a role in the osmoregulatory process. The osmoregulatory machinery of estuarine animals is more streamlined for a successful life in the estuarine regime.

Studies on scattering and thermodynamics of black holes in f(R) theory and Einstein's theory

One of the interesting consequences of Einstein's General Theory of Relativity is the black hole solutions. Until the observation made by Hawking in 1970s, it was believed that black holes are perfectly black. The General Theory of Relativity says that black holes are objects which absorb both matter and radiation crossing the event horizon. The event horizon is a surface through which even light is not able to escape. It acts as a one sided membrane that allows the passage of particles only in one direction i.e. towards the center of black holes. All the particles that are absorbed by black hole increases the mass of the black hole and thus the size of event horizon also increases. Hawking showed in 1970s that when applying quantum mechanical laws to black holes they are not perfectly black but they can emit radiation. Thus the black hole can have temperature known as Hawking temperature. In the thesis we have studied some aspects of black holes in f(R) theory of gravity and Einstein's General Theory of Relativity. The scattering of scalar field in this background space time studied in the first chapter shows that the extended black hole will scatter scalar waves and have a scattering cross section and applying tunneling mechanism we have obtained the Hawking temperature of this black hole. In the following chapter we have investigated the quasinormal properties of the extended black hole. We have studied the electromagnetic and scalar perturbations in this space-time and find that the black hole frequencies are complex and show exponential damping indicating the black hole is stable against the perturbations. In the present study we show that not only the black holes exist in modified gravities but also they have similar properties of black hole space times in General Theory of Relativity. 2 + 1 black holes or three dimensional black holes are simplified examples of more complicated four dimensional black holes. Thus these models of black holes are known as toy models of black holes in four dimensional black holes in General theory of Relativity. We have studied some properties of these types of black holes in Einstein model (General Theory of Relativity). A three dimensional black hole known as MSW is taken for our study. The thermodynamics and spectroscopy of MSW black hole are studied and obtained the area spectrum which is equispaced and different thermo dynamical properties are studied. The Dirac perturbation of this three dimensional black hole is studied and the resulting quasinormal spectrum of this three dimensional black hole is obtained. The different quasinormal frequencies are tabulated in tables and these values show an exponential damping of oscillations indicating the black hole is stable against the mass less Dirac perturbation. In General Theory of Relativity almost all solutions contain singularities. The cosmological solution and different black hole solutions of Einstein's field equation contain singularities. The regular black hole solutions are those which are solutions of Einstein's equation and have no singularity at the origin. These solutions possess event horizon but have no central singularity. Such a solution was first put forward by Bardeen. Hayward proposed a similar regular black hole solution. We have studied the thermodynamics and spectroscopy of Hay-ward regular black holes. We have also obtained the different thermodynamic properties and the area spectrum. The area spectrum is a function of the horizon radius. The entropy-heat capacity curve has a discontinuity at some value of entropy showing a phase transition.