Nijo,Varghese; Dr.Kuriakose, V C(Cochin University of Science and Technology, October , 2012)
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Abstract:
This thesis Entitled Studies on Quasinormal modes and Late-time tails black hole spacetimes. In this thesis, the signature of these new theories are probed on the evolution of field perturbations on the black hole spacetimes in the theory. Chapter 1 gives a general introduction to black holes and its perturbation formalism. Various concepts in the area covered by the thesis are also elucidated in this chapter. Chapter 2 describes the evolution of massive, charged scalar field perturbations around a Reissner-Nordstrom black hole surrounded by a static and spherically symmetric quintessence. Chapter 3 comprises the evolution of massless scalar, electromagnetic and gravitational fields around spherically symmetric black hole whose asymptotes are defined by the quintessence, with special interest on the late-time behavior. Chapter 4 examines the evolution of Dirac field around a Schwarzschild black hole surrounded by quintessence. Detailed numerical simulations are done to analyze the nature of field on different surfaces of constant radius . Chapter 5is dedicated to the study of the evolution of massless fields around the black hole geometry in the HL gravity.
Description:
Department of Physics, Cochin University of Scienceand Technology
Bernard Rajeev,S W; Dr.Sarita,Bhat G(Cochin University of Science and Technology, October , 2006)
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Abstract:
A rare horizontal gene transfer event could be traced. The movement of the
SXT element among the Vibrionaceae could be followed. This element was first
reported from Vibrio cholerae and in this study the same could be confirmed in Vibrio
alginolyticus. Events such as these, which take place with respect to other
virulence/virulence associated genes, may lead to the emergence of pathogenic strains
from hitherto non-pathogens or may even give rise to new pathogens.
The results generated in the course of this study paves way for further
characterization and detailed study, especially with respect to those strains which
showed gastric fluid accumulation in the in vivo suckling mouse assay. Antibiotic
resistance pattern shown by a sample population of Vibrios can be used for deciding
treatment options. There is enough scope for further research on these topics towards
generating basic knowledge, which can be of immense significance in human and
aquaculture health.
Description:
Department of Biotechnology,
Cochin University of Science and Technology
Sini, R; Kuriakose, V C(Cochin University of Science & Technology, September , 2008)
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Abstract:
The question of stability of black hole was first studied by Regge
and Wheeler who investigated linear perturbations of the exterior Schwarzschild spacetime. Further work on this problem led
to the study of quasi-normal modes which is believed as a characteristic sound of black holes. Quasi-normal modes (QNMs) describe
the damped oscillations under perturbations in the surrounding geometry of a black hole with frequencies and damping times of oscillations entirely fixed by the black hole parameters.In the present
work we study the influence of cosmic string on the QNMs of various
black hole background spacetimes which are perturbed by a massless
Dirac field.
Description:
Department of Physics,
Cochin University of Science and Technology
Saneesh, Sebastian; Kuriakose, V C(Cochin University of Science And Technology, December , 2014)
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Abstract:
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.
Varsha, G; Dr.Mohammed Yusuff,K K(Cochin University of Science and Technology, May , 2011)
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Abstract:
Schiff base complexes of transition metal ions have played a significant role in coordination chemistry.In the present study we have synthesized some new Mn(II),Co(II) and Cu(II) complexes of Schiff bases derived from 1,8-diaminonaphthalene.Even though we could not isolate theses Schiff bases (as they readily cyclise to form the perimidine compounds),we were able to characterize unequivacally the complexes synthesized from these compounds as complexes of Schiff Bases. We Synthesized three perimidine derivatives ,2-(quinoxalin-2-yl)-2,3-dihydro-1H-perimidine,2-(2,3-dihydro-1H-perimidin-2-yl)-6-methoxyphenol and 4-(2,3-dihyro-1H-perimidin-2-yl)-2-methoxyphenol by the condensation of 1,8-diaminonaphthalene with quinoxaline-2-carboxaldehyde,2- hydroxy-3-methoxybenzaldehyde or 4-hydroxy-3-methoxybenzaldehyde respectively.Theses compounds were used as precursor ligands for the preparation of Schiff base complexes.The complexes were characterized by using elemental analysis ,conductance and magnetic susceptibility measuremets ,infrared and UV-Visible spectroscopy ,thermogravimetric analysis and EPR spectroscopy .We also encapsulated the complexes in zeolite Y matrix and these encapsulated complexes were also characterized. We have also tried theses complexes as catalysts in the oxidation of cyclohexanol and decomposition of hydrogen peroxide.
Description:
Dept.of Applied Chemistry,Cochin University of Science and Technology
Sabu, S; Boopendranath, M R(Cochin University of Science & Technology, August , 2008)
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Abstract:
Trawling, though an efficient method of fishing, is known to be one of the most non-selective methods of fish capture. The bulk of the wild caught penaeid shrimps landed in India are caught by trawling.In addition to shrimps, the trawler fleet also catches considerable amount of non-shrimp resources. The term bycatch means that portion of the catch other than target species caught while fishing, which are either retained or discarded. Bycatch discards is a serious problem leading to the depletion of the resources and negative impacts on biodiversity. In order to minimize this problem, trawling has to be made more selective by incorporating Bycatch Reduction Devices (BRDs). There are several advantages in using BRDs in shrimp trawling. BRDs reduce the negative impacts of shrimp trawling on marine community. Fishers could benefit economically from higher catch value due to improved catch quality, shorter sorting time, lower fuel costs, and longer tow duration. Adoption of BRDs by fishers would forestall criticism by conservation groups against trawling.
Description:
Faculty of Marine Sciences
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
COCHIN-682 022
Jisha, C P; Dr.Kuriakose, V C(Cochin University of Science & Technology, March , 2008)
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Abstract:
This thesis deals with the study of light beam propagation through different
nonlinear media. Analytical and numerical methods are used to
show the formation of solitonS in these media. Basic experiments have
also been performed to show the formation of a self-written waveguide in a
photopolymer. The variational method is used for the analytical analysis
throughout the thesis. Numerical method based on the finite-difference forms of the original partial differential equation is used for the numerical
analysis.In Chapter 2, we have studied two kinds of solitons, the (2 + 1) D
spatial solitons and the (3 + l)D spatio-temporal solitons in a cubic-quintic
medium in the presence of multiphoton ionization.In Chapter 3, we have studied the evolution of light beam through a
different kind of nonlinear media, the photorcfractive polymer. We study
modulational instability and beam propagation through a photorefractive
polymer in the presence of absorption losses. The one dimensional beam
propagation through the nonlinear medium is studied using variational and
numerical methods. Stable soliton propagation is observed both analytically
and numerically.Chapter 4 deals with the study of modulational instability in a photorefractive
crystal in the presence of wave mixing effects. Modulational
instability in a photorefractive medium is studied in the presence of two
wave mixing. We then propose and derive a model for forward four wave
mixing in the photorefractive medium and investigate the modulational
instability induced by four wave mixing effects. By using the standard
linear stability analysis the instability gain is obtained.Chapter 5 deals with the study of self-written waveguides. Besides
the usual analytical analysis, basic experiments were done showing the
formation of self-written waveguide in a photopolymer system.
The formation of a directional coupler in a photopolymer system is
studied theoretically in Chapter 6. We propose and study, using the
variational approximation as well as numerical simulation, the evolution
of a probe beam through a directional coupler formed in a photopolymer system.
Description:
Department of Physics,
Cochin University of Science and Technology
This thesis deals with some aspects of the Physics of the early universe, like phase transitions, bubble nucleations and premodial density perturbations which lead to the formation structures in the universe. Quantum aspects of the gravitational interaction play an essential role in retical high-energy physics. The questions of the quantum gravity are naturally connected with early universe and Grand Unification Theories. In spite of numerous efforts, the various problems of quantum gravity remain still unsolved. In this condition, the consideration of different quantum gravity models is an inevitable stage to study the quantum aspects of gravitational interaction. The important role of gravitationally coupled scalar field in the physics of the early universe is discussed in this thesis. The study shows that the scalar-gravitational coupling and the scalar curvature did play a crucial role in determining the nature of phase transitions that took place in the early universe. The key idea in studying the formation structure in the universe is that of gravitational instability.
Bindhu, S G; Dr.Kuriakose, V C(Cochin University of Science and Technology, January , 2000)
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Abstract:
Nonlinearity is a charming element of nature and Nonlinear Science has now become one of the most important tools for the fundamental understanding of the nature. Solitons— solutions of a class of nonlinear partial differential equations — which propagate without spreading and having particle— like properties represent one of the most striking aspects of nonlinear phenomena. The study of wave propagation through nonlinear media has wide applications in different branches of physics.Different mathematical techniques have been introduced to study nonlinear systems. The thesis deals with the study of some of the aspects of electromagnetic wave propagation through nonlinear media, viz, plasma and ferromagnets, using reductive perturbation method. The thesis contains 6 chapters
Description:
Department
of Physics, Cochin University of Science and Technology
Mathew, E J; Dr.Mohammed Yusuff,K K(Cochin University of Science & Technology, November , 1990)
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Abstract:
The thesis deals with our studies on the synthesis and
elucidation of structure of some metal complexes of dithio
ligands, such as the dithiocarbamates, xanthates and
2-aminocyclopent-1-ene-1-dithiocarboxylate and its N-alkyl
derivatives.2-Aminocyclopent-1-ene-1-dithiocarboxylate (ACDA) is an
interesting ligand, because of its potential dual capability of
bonding between the metal and the ligand. Since the earlier
reports on the complexes of ACDA contain contradictory ideas on
the nature of its bonding, it was thought worthwhile to undertake
a detailed and systematic study of these type of complexes. As
the ACDA complexes have very low solubilities in solvents like
chloroform, we have used the isopropyl derivative of ACDA as the
ligand. The increased solubility of these complexes have made it
possible to investigate their NMR and solution electronic spectra.The complexes of this ligand have not yet been reported in the
literature.We have synthesised some new mixed ligand complexes of
dithiocarbamates by reacting bis(dithiocarbamato)-µ-dichloro
dicopper complexes (obtained by the reaction of mixed benzoic
dithiocarbamic anhydride and copper(II) chloride) with ACDA or its
N-alkyl derivatives.Interactions of metal halides with the mixed anhydrides
formed from benzoylchloride and xanthates have also been
investigated. Novel complexes of the type, [Cu2(RXant)CI]
(R=i-Bu, i-Pr, n-Bu or n-Pr)) have been isolated from the reaction
of copper(II) chloride and the mixed anhydride, and these
reactions appear to be like the clock reactions reported in the
literature.It also deal with the characterisation of
the complexes of the type [Hg(R2d t c )X] (X=Cl, Br or 1),[Cu3(R2dtc)6][Cu2Br6] and [Cu(R2dtc)Cl2](R2=Me2,Et2,Pip,Morph or Pyrr)respectively, synthesised by simple and novel routes,
different from those reported earlier.
Description:
Department of Applied Chemistry, Cochin
University of Science and Technology