Selven, S; Dr. Rosamma, Philip(Cochin University of Science and Technology, May , 2008)
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Abstract:
Aquaculture has developed to become one of the fastest growing food producing sectors in the world.Today India is one among the major shrimp producing countries in the world.There are extensive and intensive shrimp culture practices. In
extensive shrimp culture, shrimps are stocked at low densities (< 25 PLs m'2)in large ponds or tidal enclosures in which little or no management is exercised or possible. Farmers depend almost entirely on natural conditions in extensive cultures. Intensive shrimp culture is carried out in
high densities (>200 PLs m'2). Much of the world shrimp production still comes from extensive culture.There is a growing demand for fish and marine products for human and animal consumption. This demand has led to rapid growth of
aquaculture, which some times has been accompanied by ecological impacts and economic loss due to diseases. The expansion of shrimp culture always accompanies local environmental degradation and
occurrence of diseases.Disease out breaks is recognised as a significant constraint to aquaculture production. Environmental factors, water quality, pollution due to effluent discharge and pathogenic invasion due to vertical
and horizontal transmission are the main causes of shrimp disease out breaks. Nutritional imbalance, toxicant and other pollutants also account for the onset of diseases.
pathogens include viruses, bacteria, fungi and parasites.Viruses are the most economically significant pathogens of the cultured shrimps world wide. Disease control in shrimp aquaculture should focus first on preventive measures for eliminating disease promoting factors.ln order to design prophylactic and proactive measures against shrimp diseases, it is mandatory to understand the immune make up of the cultivable species,
its optimum culture conditions and the physico chemical parameters of the rearing environment. It has been proven beyond doubt that disease is an end result of complex interaction of environment, pathogen and the host animal. The aquatic environment is abounded with infectious microbes.The transmission of disease in this environment is extremely easy,
especially under dense, culture conditions. Therefore, a better understanding of the immune responses of the cultured animal in relation to its environmental alterations and microbial invasions is essential indevising strategic measures against aquaculture loss due to diseases. This study accentuate the importance of
proper and regular health monitoring in shrimps employing the most appropriate haematological biomarkers for application of suitable prophylactic measures in order to avoid serious health hazards in shrimp culture systems.
Biju,M P; Pyroja,Sulainian; Rajeshkumar,Neelimmathara V; Paulose,C S(Department of Biotechnology, February 15, 2001)
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Abstract:
Gamma aminohutyric acid (GAB A.) receptor tunctionaI status was artaIV se(l in pa It ial hcpatcctoIn ised.II'II). lead
nitrate (LN) induced hyperplastic and N-nifrosodiethylantinc INDEAI treated nctplastic rat Iivers during peak DNA
synthesis. The high-affinity I'HJGALA binding significantly decreased in PII and NDEi\ rats and the receptor affinity
decreased in NDEA and increased in LN rats compared with control . in NDEA. displacement analysis of I'I IIGABA
with muscimol showed loss of low-allinity site and a shill of high-allinity cite towards low-allinity . ' 1 he affinity sites
shifted towards high-affinity in LN rats. 'file number of low-allinity 1'I Ilhicuc)lline receptors decreased cignilic:uttly
in NDEA and I'll whereas it increased in LN rats. (ir\Bi\t receptor :gunist. unrscinrul. disc dependcnllyinhihilcd
epidermal growth factor IEGI--) induced DNA synthesis :uul enhanced the tr:utsfnrnting grmvth )actor (Il I I'(il (tlI
mediated DNA synthesis suppression in prim:uy hepalucvte cultures . Our results suggest that GABA,t reccjhtor act
as an inhibitory signal fur hepatic cell prolifctatiun.
Heterotrophic bacterial flora of Pmonadon from an apparently healthy hatchery system as well as a pool with heavy mortality were isolated and studied. In the
healthy systems comparatively higher generic diversity with Pseudomonas, Acinetobacter, Bacillus, Micrococcus, members of the family Enterobacteriaceae
and coryneform group in the diminishing order of dominance was recorded. Meanwhile from the moribund larvae and rearing water Aeromonas and Pseudomonas
could be isolated in almost equal proportions. Strikingly, Aeromonas could not be isolated from the apparently healthy larval rearing system and its exclusive
occurrence in the sick culture system in comparatively higher percentage suggested its possible role in the mortality. They were found to be highly halophilic
exhibiting growth at 10% NaCl. On testing their sensitivity to twenty antibiotics, four of them (Streptomycin, Gentamycin, Methamine mandelate and
Cloramphenicol) were found to be effective on all the isolates of Aeromonas and Pseudomonas suggesting their possible application in the hatchery system in
times of emergency. While doing so, Streptomycin would do comparatively better than the others as the minimum inhibitory dose required was comparatively
lower (200ppm) within a period of 24 hours
Hamsakutty, V; Dr. Mathew, K T(Cochin University of Science and Technology, March , 2007)
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Abstract:
In this thesis, the author proposes a new geometry DR antenna-the Hexagonal Dielectric Resonator Antenna(HDRA)-capable of multiple frequency operation on a single feed of excitation.This avoids the conventional use of miniaturizes the structure.The properties of the HDRA on microstrip as well as coaxial feeding have been studied.The analysis of radiation characteristics indicates a gain comparable with other shapes.The antenna is capable of providing efficiency around 98%.The simulation using HFSS also yields results in conformity with the experimental results.Mode analysis is carried out and the modes are identified.The determination of the reflection characteristics through theoretical analysis using FDTD validates the multifrequency operation of the antenna,The antenna finds application in DCT,PCS and WLAN bands.
Description:
Department of
Electronics, Cochin University of Science and Technology
Vimalkumar, T V; Dr. Vijayakumar, K P(Cochin University of Science & Technology, August , 2011)
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Abstract:
In the present work we report the preparation details studies on ZnO thin films. ZnO
thin films are prepared using cost effective deposition technique viz., Chemical Spray
Pyrolysis (CSP). The method is very effective for large area preparation of the ZnO thin
film. A new post-deposition process could also be developed to avoid the adsorption of
oxygen that usually occurs after the spraying process i.e., while cooling. Studies were done
by changing the various deposition parameters for optimizing the properties of ZnO thin
film. Moreover, different methods of doping using various elements are also tried to
enhance the conductivity and transparency of the film to make these suitable for various
optoelectronic applications.
Description:
Department of Physics,
Cochin University of Science and Technology
A new group of compounds with composition (Ba5-xSrx) Nb4015, having high
permittivity and low loss have been prepared and characterized in the microwave
frequency region . X-ray diffraction studies showed that monophase compound
existed for all values of x from 0 to 5. Microwave dielectric properties such as
and c f showed smooth variation with x , while the unloaded quality factor (Qu)
showed remarkable improvement with x
Thomas, Baby; Sathianandan, K; Nampoori, V P N; Vallabhan, C P G; Ramachandran, T(American Institute of Physics, September , 1991)
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Abstract:
A high power Nz laser of the double-Blumlein type having a modified gas flow system,
electrode configuration, and discharge geometry with minimum inductance is described. By
incorporating a triggere’d-pressurized spark gap switch, arc-free operation was achieved
for a wide E/P range. The device gives a peak power in excess of 700 kW with a FWHM of
3 ns and an efficiency of 0.51%, which is remarkably high for a pulsed nitrogen laser
system. The dependence of output power on parameters such as operating pressure, voltage,
and repetition rate are discussed.
Sasi Kumar, P R; Harilal, S S; Nampoori, V P N; Vallabhan, C P G(Pramana, March , 1994)
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Abstract:
High resolution optogalvanic spectrum of the (11, 7) band in the first positive system
of nitrogen molecule has been recorded from 17179 to 17376 cm- 1. Assignment of 432 rotational
lines belonging to the 27 branches of this band has been carried out.
Sasi Kumar, P R; Ambadi, B; Nampoori, V P N; Vallabhan, C P G(Springer, February , 1993)
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Abstract:
Doppler limited high resolution spectrum in the wavelength region 17224 to 17236 cm−1 of the first positive system (B 3Π g −A 3Σ u + ) of the N2 molecule is recorded by optogalvanic spectroscopic technique using a single mode ring dye laser. It is observed that the intensity and line width of the rotational line increase with the discharge current. Dependence of the collision broadening coefficient on the current was also evaluated.
Subhadra, V K; Syamaprasad, U; Vallabhan, C P G(American Institute of Physics, 1983)
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Abstract:
Results of axiswise measurements of the electrical conductivity (dc and ac) and dielectric constant of NH4H2PO4 confirm the occurrence of the recently suggested high‐temperature phase transition in this crystal (at 133 °C). The corresponding transition in ND4D2PO4 observed here for the first time takes place at 141.5 °C. The mechanism involved in these transitions and those associated with the electrical conduction and dielectric anomalies are explained on the basis of the motional effects of the ammonium ions in these crystals. Conductivity values for deuterated crystals give direct evidence for the predominance of protonic conduction throughout the entire range of temperatures studied (30–260 °C).