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Ali H.A.J.,Islamiah College | Tamilselvi M.,Vv Vanniaperumal College For Women | Sivakumar V.,Director of Research and Conservation
Indian Journal of Geo-Marine Sciences | Year: 2014

V. O. Chidambaram port, formerly Tuticorin port, is one among the 12 major ports in India with regular services to United States, Europe, China, Red sea port and Mediterranean countries and so serving as gateway for bioinvasion. Ascidians belonging to the Class Ascidiacea of sub-Phylum Tunicata are abundant in many ports around the world and most of them are non-indigenous. They are one of the key ecological groups because of their invasive potential and ability to thrive in eutrophic environments. During a survey of the port area over the past three years (2011-2013), sixteen species of ascidians were identified belonging to diverse families: Ascidiidae (4), Styelidae (2), Pyuridae (4), Polycitoridae (2), and Didemnidae (4). Among the identified species, Phallusia nigra, P. arabica, Ascidia gemmata, Microcosmus exasperates, Herdmania pallida, Eudistoma viride, E. laysani, Didemnum psammatode and Diplosoma similis are classified as cryptogenic species while M. squamiger, M. stoloniferus, Styela canopus, A. sydneiensis Didemnum candidum, Lissoclinum fragile and Eusynstyela tincta are invasive species. Presence of large number of cryptogenic and invasive ascidians in this harbour reinforces the need for continued and periodic monitoring of population expansion of these species and also for establishment of control programme. Utilization of non-indigenous ascidians for the betterment of humankind may be considered as one of management strategies of non-indigenous species. © 2014, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.

Azhagu Parvathi A.,Vv Vanniaperumal College For Women | John Peter A.,Government Arts College
Acta Physica Polonica A | Year: 2013

Hydrogenic donor impurity binding energy is obtained in a ZnxCd1-xTe/ZnTe strained quantum dot taking into account the phonon confinement effect. The interaction of the electron and the phonon modes are expressed in terms of the Fröhlich interaction Hamiltonian. The binding energy is obtained for various Zn composition using the Aldrich-Bajaj effective potential. Calculations have been obtained using the Bessel function as an orthonormal basis for different confinement potentials of barrier height considering the internal electric field induced by the spontaneous and piezoelectric polarizations. Polaron induced linear and third-order nonlinear optical absorption coeffcients and the changes of refractive index as a function of incident photon energy are observed. Our results coincide with the recent observations of a hydrogenic impurity binding energy in a CdTe/ZnTe quantum dot solved analytically. It is observed that the potential taking into account the effects of phonon makes the hydrogenic binding energies larger than the obtained results using a Coulomb potential screened by a static dielectric constant and the optical properties of hydrogenic impurity in a quantum dot are strongly affected by the confining potential and the quantum size. It is found that the geometry of the quantum dot, zinc concentration and the effect of phonon have a great influence on the absorption coefficient and refractive index changes of the dot. It is also bserved that the magnitude of the absorption coefficients enhances with the inclusion of phonon effect.

Parvathi A.A.,Vv Vanniaperumal College For Women | Peter A.J.,Government Arts and Science College | Yoo C.K.,Kyung Hee University
Chinese Physics Letters | Year: 2013

Exciton binding energy, interband emission energy, oscillator strength, and some nonlinear optical properties in quantum dots made up of polar semiconductors are computed with the geometrical confinement. The effects of the interaction of charge carriers with the longitudinal optical phonons on the exciton binding energy are included. The anisotropy of the effective masses of holes is incorporated throughout the calculations. Nonlinear optical exciton absorption of II - VI systems based on some polar semiconductors in the presence of LO phonons is discussed. The optical rectification coefficient associated with the intersubband transitions in a quantum dot of polar semiconductors is investigated. Changes of refractive index with the photon energy in a polar quantum dot are found. Our results show that the polar bound excitons in II - VI based polar semiconductors depend on the geometrical confinement, and the nonlinear optical properties strongly depend on the polar materials. © 2013 Chinese Physical Society and IOP Publishing Ltd.

Sumathi M.,Sri Meenakshi Government College for Women | Barani R.,Vv Vanniaperumal College For Women
International Conference on Pattern Recognition, Informatics and Medical Engineering, PRIME 2012 | Year: 2012

Image fusion is the process of combining information from two or more images of a same scene into a single composite image that is more informative and is more suitable for visual perception or computer processing. The main objective of this paper is to implement the various pixel level fusion algorithms and to determine how well the information contained in the source images are represented in the fused images on multimodality and multifocusing images. Experiments and qualitative metrics dictate that Laplacian Pyramid method performs better on both multimodality and multifocusing images. © 2012 IEEE.

Parvathi A.A.,Vv Vanniaperumal College For Women | Peter A.J.,Government Arts and Science College | Yoo C.K.,Kyung Hee University
Journal of Computational and Theoretical Nanoscience | Year: 2014

Cadmium doped zinc oxide powders with different concentrations of cadmium are prepared by wet chemical method. The electronic transitions are investigated by UV transmission spectra and compared with the interband emission energy computed theoretically. The exciton binding energy in the wurtzite strained CdxZn1-xO/ZnO quantum dot, grown along 〈0001〉 polar direction, is computed considering the internal electric field induced by the spontaneous and piezoelectric polarizations. Numerical calculations are carried out using single band effective mass approximation with the variational scheme to compute the exciton binding energy and the optical transition energry. Geometrical effects on optical properties of strained CdxZn 1-xO/ZnO quantum dots are discussed. The nonlinear optical properties are obtained using the compact density matrix approach. The linear, third order non-linear optical absorption coefficients, susceptibility values and the refractive index changes with the photon energy are obtained. Our numerical results are in good agreement with the experimental results. Copyright © 2014 American Scientific Publishers All rights reserved.

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