Dakshinamurti,K; Paulose,C S; Viswanathan,M; Siow,Y L(Department of Biotechnology, 1988)
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Abstract:
Veuruenducrim lri v j p .rim,
deficienc:v. NEUROSCI BIOBEHAV REV 12(3/4) 189-193. 1988.- Dihydroxyphenylalanine decarboxvlase and
5-hydroxytryptophan decarboxvlase respectively have high and low affinities for pyridoxal phosphate. In the pyridoxinedeficient
animal. hypothalamic serotonin content is significantly reduced without any change in catecholamine levels.
Hypothalamic neurotransmitters affect the hvpothalamo-pituitary-end organ axes. Specifically, the decrease in hypothalamic
serotonin in the pyridoxine-deficient rat results in tertiary hypothyroidism. In addition. pineal function is affected in
deficient animals due to decreased synthesis of melatonin.
Viswanathan,M; Siow,Y L; Paulose,C S; Dakshinamurti,K(Department of Biotechnology, May 24, 1988)
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Abstract:
Pvridoxine deficiency causes physiologically significant decrease in brain serotonin (5-HT) due to decreased decarboxylation of 5-
hvdroxvtrvptophan (5-HTP). We have examined the effect of pyridoxine deficiency on indoleamine metabolism in the pineal gland, a
tissue with high indoleamine turnover. Adult male Sprague-Dawley rats were fed either a pyridoxine-supplemented or pyridoxinedeficient
diet for 8 weeks. Pyridoxine deficiency did not alter the pattern of circadian rhythm of pineal 5-HT. 5-hvdroxvindoleacetic
acid (5-HIAA), V-acetvlserotonin (NAS). and melatonin. However the levels of these compounds were significantly lower in the
pineal glands of pyridoxine-deficient animals. Pineal 5-HTP levels were consistently higher in the pyridoxine-deficient animals and a
conspicuous increase was noticed at 22.00 h. Increase in pineal NAS and melatonin levels caused by isoproterenol (5 mg kg at 17.00 h)
were significantly lower (P < 0.05) in the pyridoxine-deficient animals. Treatment of pyridoxine-deficient rats with pvridoxine restored
the levels of pineal 5-HT, 5-HIAA. NAS. and melatonin to values seen in pyridoxine-supplemented control animals. These results
suggest that 5-HT availability could be an important factor in the regulation of the synthesis of pineal NAS and melatonin.
Ravisankar, M; Reghunath, A T; Sathianandan, K; Nampoori, V P N(Optical Society of America, September 15, 1988)
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Abstract:
The split-pulse laser method is used to reinvestigate the optical attenuation of distilled water in the region from 430 to 630 nm. The studies are then extended to ionic solutions of NaCl, MgCl2, and Na2SO4, these salts forming the major constituents of seawater. The effect of the concentration of these constituents on optical attenuation is investigated. Further, optical attenuation studies are carried out for the region from 430 to 630 nm for an aqueous solution prepared with all the major constituents in the same proportions as in natural seawater. These values are then compared with values obtained for natural seawater. The relative role of dissolved salts and suspended particles on optical attenuation in seawater is discussed. The lowest attenuation is observed at ~450 nm for all solutions and is found to coincide with that for distilled water.
Harikrishnan, K P; Nandakumaran, V M(Elsevier, November 21, 1988)
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Abstract:
We analyse numerically the bifurcation structure of a two-dimensional noninvertible map and show that different periodic cycles are arranged in it exactly in the same order as in the case of the logistic map. We also show that this map satisfies the general criteria for the existence of Sarkovskii ordering, which supports our numerical result. Incidently, this is the first report of the existence of Sarkovskii ordering in a two-dimensional map.
Reethamma, Thomas; Nampoori, V P N(Elsevier, December , 1988)
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Abstract:
Photoluminescence, thermoluminescence and phosphorescence studies of cerium and copper doped BaS phosphors are attempted. Cu+ centres in BaS lattice activate red emission while Ce3+ sensitize the blue emission. Results are explained on the basis of superposition theory involving monomolecular kinetics. In Randall and Wilkins model, the decay and TL studies are found to corelate each other.
Jayaraj, M K; Vallabhan, C P G(IOP Publishing, 1989)
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Abstract:
The method of preparation of ZnS phosphors doped with praseodymium and copper is given. The electroluminescence (EL) spectrum of ZnS:Pr,Cl has two broad bands at 470 and 570 nm. ZnS:Cu,Pr,Cl gives white emission with spectral peaks at 470, 520, 570 and 640 nm. The EL spectra of both types of phosphor exhibit a conspicuous colour shift as the frequency of the excitation voltage is varied. Detailed investigations show that the relative intensities of spectral peaks are strongly dependent on the frequency of the excitation voltage. The colour shift is explained on the basis of the Schon-Klasens model.
Wilson,K J; Vallabhan, C P G(IOP Publishing, 1989)
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Abstract:
A simple and inexpensive linear magnetic field sweep generating system suitable for magnetic resonance experiments is described. The circuit, utilising a modified IC bootstrap configuration, generates field sweep over a wide range of sweep durations with excellent sweep linearity.
Paulose,C S; Thliveris,J A; Dakshinamurti,K; Viswanathan,M(Department of Biotechnology, 1989)
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Abstract:
We have studied testicular function in the biotin-
deficient rat biochemically and morphologically.
Serum testosterone and luteinizing hormone (LH) levels
were decreased significantly in the deficient rats. Administration
of biotin or gonadotropins to the deficient rats
reversed this decrease in serum testosterone. There was no
difference in the serum cholesterol level between the control
and biotin-deficient rats. A significant degree of sloughing
of seminiferous tubule germinal epithelium was noticed
in the biotin-deficient rat testes. Biotin treatment of biotindeficient
rats reversed this condition whereas testosterone
treatment was without any effect. The development and
maintenance of morphological and functional integrity of
the seminiferous tubules appears to require a biotin-mediated
step in addition to testosterone.
Navil Kumar, R; Vallabhan, C P G(IOP Publishing, 1989)
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Abstract:
DC and AC electrical conductivity measurements in single crystals of diammonium hydrogen phosphate along the c axis show anomalous variations at 174, 246 and 416 K. The low-frequency dielectric constant also exhibits peaks exactly at these temperatures with a thermal hysteresis of 13 degrees C for the peak at 416 K. These specific features of the electrical properties are in agreement with earlier NMR second-moment data and can be identified with three distinct phase transitions that occur in the crystal. The electrical conductivity values have been found to increase linearly with impurity concentration in specimens doped with a specific amount of SO42- ions. The mechanisms of the phase transition and of the electrical conduction process are discussed in detail.
Padmaja, G; Ravi Kumar, A V; Vidyalal, V; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(IOP Publishing, 1989)
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Abstract:
In order to characterise the laser ablation process from high-Tc superconductors, the time evolution of plasma produced by a Q-switching Nd:YAG laser from a GdBa2Cu3O7 superconducting sample has been studied using spectroscopic and ion-probe techniques. It has been observed that there is a fairly large delay for the onset of the emission from oxide species in comparison with those from atoms and ions of the constituent elements present in the plasma. Faster decay occurs for emission from oxides and ions compared with that from neutral atoms. These observations support the view that oxides are not directly produced from the target, but are formed by the recombination process while the plasma cools down. Plasma parameters such as temperature and velocity are also evaluated.
Lalaja, V; Nampoori, V P N; Pratap, R(Kluwer Academic Publishers, February , 1989)
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Abstract:
The theory of deterministic chaos is used to study the three rings A, B, and C of Saturn and the French and Cassini divisions in between them. The data set comprises Voyager photopolarimeter measurements. The existence of spatially distributed strange attractors is shown, implying that the system is open, dissipative, nonequilibrium, and non-Markovian in character.
Padmaja, G; Ravi Kumar, A V; Vidyalal, V; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(Springer, May , 1989)
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Abstract:
Laser induced plasma emission spectra from highT c superconducting samples of YBa2Cu3O7 and GdBa2Cu3O7 obtained with 1.06µm radiation from a Q switched Nd:YAG laser beam has been analysed. The results clearly show the presence of diatomic oxides in addition to ionized species of the constituent metals in the plasma thus produced.
Abdul Rasheed, T M; Moosad, K P B; Nampoori, V P N; Sathianandan, K(Springer, September , 1989)
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Abstract:
Vibrational overtone spectra of styrene (liquid) and polystyrene (solid), studied by the laser-induced thermal lens (for ΔV=6) and the conventional near infrared absorption (for ΔV=3–5) techniques, are reported. For polystyrene, the overtone energy-bond length correlation predicts that the aryl CH bonds are ∼0.0005 Å longer than that in benzene, while no such conclusions could be drawn on styrene. Thesp 3 CH overtones in polystyrene are observed on the low energy side of the aryl CH overtones.
Jayaraj, M K; Vallabhan, C P G(Elsevier, October , 1989)
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Abstract:
The dielectric properties of vacuum-deposited europium oxide films have been investigated in the frequency range from 1 kHz to 1 MHz at various temperatures (300-543 K). The dielectric constant is found to depend on film thickness and it attains a constant value beyond 1000 Å. Films deposited at higher substrate temperatures (above 423 K) exhibit improved dielectric properties owing to the recovery of stoichiometry. The frequency variation of the loss factor exhibits a minimum which increases with rise in temperature. The breakdown field strength (about 106V cm-1) is found to be thickness dependent and it varies in accordance with the Forlani-Minnaja relation. The films exhibit ohmic conduction with an activation energy of 0.86 eV at low electric fields but at higher fields the conductivity becomes space charge limited. X-ray studies show that the films are amorphous in nature. The a.c. conductivity is proportional to ω at low frequency, whereas a square law dependence is observed at higher frequencies. The optical constants n, α and k and optical band gap are calculated from the UV-visible-near-IR spectra.
Ravi Kumar, A V; Padmaja, G; Nampoori, V P N; Vallabhan, C P G(Springer, November , 1989)
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Abstract:
Absorption spectra of formaldehyde molecule in the gas phase have been recorded using photoacoustic (PA) technique with pulsed dye laser at various power levels. The spectral profiles at higher power levels are found to be different from that obtained at lower laser powers. Two photon absorption (TPA) is found to be responsible for the photoacoustic signal at higher laser power while the absorption at lower laser power level is attributed to one photon absorption (OPA) process. Probable assignments for the different transitions are given in this paper.
Viswanathan,M; Paulose,C S; Lal,K J; Sharma,S K; Dakshinamurti,K(Department of Biotechnology, November 27, 1989)
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Abstract:
Moderate pyridoxine deficiency in adult male Sprague-Dawley rats results in significant hypertension,
associated with a general sympathetic stimulation , including an increase in the turnover of norepinephrine
in the heart. Treatment of these rats with pyridoxine reversed blood pressure to normal within 24 h. Treatment
of pyridoxine-deficient rats with clonidine or x-methyl dihydroxyphenylalanine (x-methyl DOPA)
also reduced the blood pressure of these animals to normal . There was also a significant increase in the
Bma, of high and low affinity [3H]p-amino-clonidine binding to crude synaptosomal membrane preparations
of the brain stem of deficient rats indicating chronic underexposure of)(, adrenoreceptors to endogenous
norepinephrin.
Sreekumar, J; Nandakumaran, V M(Springer, December , 1989)
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Abstract:
The dynamics of saturated two-dimensional superfluid4He films is shown to be governed by the Kadomtsev-Petviashvili equation with negative dispersion. It is established that the phenomena of soliton resonance could be observed in such films. Under the lowest order nonlinearity, such resonance would happen only if two dimensional effects are taken into account. The amplitude and velocity of the resonant soliton are obtained.
Harikrishnan, K P; Nandakumaran, V M(Elsevier, December 25, 1989)
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Abstract:
This is a sequel to our earlier work on the modulated logistic map. Here, we first show that the map comes under the universality class of Feigenbaum. We then give evidence for the fact that our model can generate strange attractors in the unit square for an uncountable number of parameter values in the range μ∞<μ<1. Numerical plots of the attractor for several values of μ are given and the self-similar structure is explicity shown in one case. The fractal and information dimensions of the attractors for many values of μ are shown to be greater than one and the variation in their structure is analysed using the two Lyapunov exponents of the system. Our results suggest that the map can be considered as an analogue of the logistic map in two dimensions and may be useful in describing certain higher dimensional chaotic phenomena.
Ramachandran, A; Rajendra, Badonia; Viswanathan Nair, P G(Society of fisheries Technologists (India), 1990)
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Abstract:
Effect of delayed icing on the microbial quality and shelf-life of Hilsa toll was studied
. Fish iced in rigor condition had a shelf-life of 11 days irrespective of the state
of rigor . Fish procured from the landing centre had a shelf-life of only 8 days . It
showed the presence of coagulase positive staphylococci, faecal streptococci and E. coli.
Total bacterial count was low in all the samples and it increased after spoilage
Ramachandran, A; Sankar, T V(Society of Fisheries Technologists (India), 1990)
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Abstract:
The whale shark (Rhiniodon typus Smith) is an under exploited species and it is
mainly caught for its liver oil . The processing of shark fin for rays is reported here .
The fins have a high content of rays . The yield of fin rays from undried fins ranged
from 0 .53 to 4 .40 percent with maximum ray content in the lower lobe of caudal fin .
The physical and chemical characteristics of the rays are reported . The total nitrogen
content is about 15 to 16 percent (dry weight basis)