Showing papers by "Indian Institute of Science published in 1975"
TL;DR: The intercation between a galactose-specific lectin from Ricinus communis beans and liposomes containing different amounts of monosialoganglioside is studied, and it is found that the latter can be used as a model system for the investigation of agglutination of cells by lectins.
Abstract: A MODEL has been presented showing the contribution of the protein–glycoprotein complex1–3 when transformed cells are agglutinted by lectins4–6. But this has not been possible for the lectin–glycolipid complex because glycolipids form micelles, even at very low concentrations. This difficulty could be overcome by incorporating these glycolipids into lipid vesicles. (Haywood demonstrated that ganglioside incorporated in liposome can provide receptors for sendai virus7.) We have now studied the intercation between a galactose-specific lectin from Ricinus communis beans1,8,9 and liposomes containing different amounts of monosialoganglioside (GM1), and found that the latter can be used as a model system for the investigation of agglutination of cells by lectins.
133 citations
TL;DR: In the coccid insects, imprinting occurs in the egg, at the time of fertilisation; it probably occurs at the same time and site in mammals, and possibly also in Sciara.
Abstract: Chromosome imprinting is the process by which one of two genetically homologous chromosomes is predetermined to function differently from the other at a subsequent stage in development. In the coccid insects, imprinting occurs in the egg, at the time of fertilisation; it probably occurs at the same time and site in mammals, and possibly also in Sciara.
100 citations
TL;DR: In this paper, a branched crack consisting of a main crack and a straight branch starting from one of its tip located in an infinite elastic sheet is considered under the assumptions of two-dimensional theory of Elasticity.
95 citations
TL;DR: It is shown that the points of excitation of the vocal tract can be precisely identified for continuous speech and it is possible to obtain accurate pitch information by this method even for high-pitched sounds.
Abstract: A general theory of epoch extraction of overlapping nonidentical waveforms is presented. The theory is applied to outputs of models of voiced speech production mechanism and to actual speech data. Some typical glottal waveshapes are considered to explain their effect on the speech output. It is shown that the points of excitation of the vocal tract can be precisely identified for continuous speech. It is possible to obtain accurate pitch information by this method even for high-pitched sounds. The epoch extraction has wide applications in speech analysis, speaker verification, speech synthesis, and pitch perception studies.
89 citations
01 May 1975
TL;DR: In this paper, the application of Walsh functions to the time-domain synthesis problem is discussed, i.e., the determination of a suitable internal structure for a system from its prescribed external (input/output) behaviour.
Abstract: The paper deals with the application of Walsh functions to the time-domain-synthesis problem, i.e., the determination of a suitable internal structure for a system from its prescribed external (input/output) behaviour. The method is based on repeated integration, and a new operational matrix, which relates Walsh functions and their integrations, is defined. Examples of transfer-function and state-equation synthesis are used to illustrate the technique.
87 citations
TL;DR: It is concluded on the basis of very well oriented diffraction patterns that the structure of 5′-GMP consists of a continuously hydrogen-bonded helix with 15 nucleotides in four turns.
75 citations
TL;DR: In this article, the authors considered the unsteady laminar compressible boundary-layer flow in the immediate vicinity of a two-dimensional stagnation point due to an incident stream whose velocity varies arbitrarily with time, and the governing partial differential equations involving both time and the independent similarity variable were transformed into new co-ordinates with finite ranges by means of a transformation which maps an infinite interval into a finite one.
Abstract: The unsteady laminar compressible boundary-layer flow in the immediate vicinity of a two-dimensional stagnation point due to an incident stream whose velocity varies arbitrarily with time is considered. The governing partial differential equations, involving both time and the independent similarity variable, are transformed into new co-ordinates with finite ranges by means of a transformation which maps an infinite interval into a finite one. The resulting equations are solved by converting them into a matrix equation through the application of implicit finite-difference formulae. Computations have been carried out for two particular unsteady free-stream velocity distributions: (i) a constantly accelerating stream and (ii) a fluctuating stream. The results show that in the former case both the skin-friction and the heat-transfer parameter increase steadily with time after a certain instant, while in the latter they oscillate, thus responding to the fluctuations in the free-stream velocity.
74 citations
TL;DR: In this paper, an expression for attenuation (insertion loss) of a muffler has been proposed in terms of convective terminal impedances and a velocity ratio, on the lines of the one existing for acoustic filters.
74 citations
TL;DR: Under certain special conditions natural selection can be effective at the level of local populations, or demes, and will favor genotypes that reduce the probability of extinction of their parent population even at the cost of a lowered inclusive fitness.
Abstract: Under certain special conditions natural selection can be effective at the level of local populations, or demes. Such interpopulation selection will favor genotypes that reduce the probability of extinction of their parent population even at the cost of a lowered inclusive fitness. Such genotypes may be characterized by altruistic traits only in a viscous population, i.e., in a population in which neighbors tend to be closely related. In a non-viscous population the interpopulation selection will instead favor spiteful traits when the populations are susceptible to extinction through the overutilization of the habitat, and cooperative traits when it is the newly established populations that are in the greatest danger of extinction.
63 citations
TL;DR: In this article, conditions for obtaining 2 -5 μm thick continuous coatings of copper on 2 -200 μm diameter graphite particles using aqueous and supersaturated copper sulphate solution by cementation processes have been optimised.
59 citations
TL;DR: The enzyme was shown to be homogeneous by electrophoretic and immunological criteria, had a molecular weight of 220000 and appears to be a hexamer with identical subunits, and follows typical Michaelis-Menten kinetics with a Km value of 1.73 mM for arginine.
Abstract: Arginine decarboxylase which makes its appearance in Lathyrus sativus seedlings after 24 h of seed germination reaches its highest level around 5–7 days, the cotyledons containing about 60% of the total activity in the seedlings at day 5. The cytosol enzyme was purified 977-fold from whole seedlings by steps involving manganese chloride treatment, ammonium sulphate and acetone fractionations, positive adsorption on alumina C-γ gel, DEAE-Sephadex chromatography followed by preparative disc gel electrophoresis. The enzyme was shown to be homogeneous by electrophoretic and immunological criteria, had a molecular weight of 220000 and appears to be a hexamer with identical subunits. The optimal pH and temperature for the enzyme activity were 8.5 and 45 °C respectively. The enzyme follows typical Michaelis-Menten kinetics with a Km value of 1.73 mM for arginine. Though Mn2+ at lower concentrations stimulated the enzyme activity, there was no dependence of the enzyme on any metal for the activity. The arginine decarboxylase of L. sativus is a sulfhydryl enzyme. The data on co-factor requirement, inhibition by carbonyl reagents, reducing agents and pyridoxal phosphate inhibitors, and a partial reversal by pyridoxal phosphate of inhibition by pyridoxal · HCl suggests that pyridoxal 5'-phosphate is involved as a co-factor for the enzyme. The enzyme activity was inhibited competitively by various amines including the product agmatine. Highest inhibition was obtained with spermine and arcain. The substrate analogue, l-canavanine, homologue l-homoarginine and other basic amino acids like l-lysine and l-ornithine inhibited the enzyme activity competitively, homoarginine being the most effective in this respect.
TL;DR: Steady-state rates of phenylalanine ammonia-lyase reaction in the presence of inhibitors have shown that only one molecule of each type of inhibitor binds to a molecule of the enzyme, suggesting the involvement of negative homotropic interactions in phenylAlanine ammonia -lyase.
Abstract: 1. Phenylalanine ammonia-lyase (EC 4.3.1.5) was purified to homogeneity from the acetone-dried powders of the mycelial felts of the plant pathogenic fungus Rhizoctonia solani. 2. A useful modification in protamine sulphate treatment to get substantial purification of the enzyme in a single-step is described. 3. The purified enzyme shows bisubstrate activity towards L-phenylalanine and L-tyrosine. 4. It is sensitive to carbonyl reagents and the inhibition is not reversed by gel filtration. 5. The molecular weight of the enzyme as determined by Sephadex G-200 chromatography and sucrose-density-gradient centrifugation is around 330000. 6. The enzyme is made up of two pairs of unidentical subunits, with a molecular weight of 70000 (alpha) and 90000 (beta) respectively. 7. Studies on initial velocity versus substrate concentration have shown significant deviations from Michaelis-Menten kinetics. 8. The double-reciprocal plots are biphasic (concave downwards) and Hofstee plots show a curvilinear pattern. 9. The apparent Km value increases from 0.18 mM to as high as 5.0 mM with the increase in the concentration of the substrate and during this process the Vmax, increases by 2-2.5-fold. 10. The value of Hill coefficient is 0.5. 11. Steady-state rates of phenylalanine ammonia-lyase reaction in the presence of inhibitors like D-phenylalanine, cinnamic, p-coumaric, caffeic, dihydrocaffeic and phenylpyruvic acid have shown that only one molecule of each type of inhibitor binds to a molecule of the enzyme. These observations suggest the involvement of negative homotropic interactions in phenylalanine ammonia-lyase. 12. The enzyme could not be desensitized by treatment with HgCl2, p-chloromercuribenzoic acid or by repeated freezing and thawing.
TL;DR: By using the perturbation technique, a Kortewege-de-Vries (K-dV) equation for a multicomponent plasma with negative ions and isothermal electrons has been derived.
Abstract: By using the perturbation technique, a Kortewege-de-Vries (K-dV) equation for a multicomponent plasma with negative ions and isothermal electrons has been derived. We have discussed the stationary solutions of K-dV equation and it has shown that in the presece of multiple ions, the amplitude of solitons exhibits interesting behaviour, especiallY when the negative ions are present.
TL;DR: In this article, peroxidase from Mycobacterium tuberculosis H37Rv was purified to homogeneity, and the homogeneous protein exhibits catalase and Y (Youatt's)-enzyme activities.
Abstract: Peroxidase from Mycobacterium tuberculosis H37Rv was purified to homogeneity. The homogeneous protein exhibits catalase and Y (Youatt's)-enzyme activities in addition to peroxidase activity. Further confirmation that the three activities are due to a single enzyme was accomplished by other criteria, such as differential thermal inactivation, sensitivity to different inhibitors, and co-purification. The Y enzyme (peroxidase) was separated from NADase (NAD+ glycohydrolase) inhibitor by gel filtration on Sephadex G-200. The molecular weights of peroxidase and NADase inhibitor, as determined by gel filtration, are 240000 and 98000 respectively. The Y enzyme shows two Km values for both isoniazid (isonicotinic acid hydrazide) and NAD at low and high concentrations. Analysis of the data by Hill plots revealed that the enzyme has one binding site at lower substrate concentrations and more than one at higher substrate concentration. The enzyme contains 6g-atoms of iron/mol. Highly purified preparations of peroxidases from different sources catalyse the Y-enzyme reaction, suggesting that the nature of the reaction may be a peroxidatic oxidation of isoniazid. Moreover, the Y-enzyme reaction is enhanced by O2. Isoniazid-resistant mutants do not exhibit Y-enzyme, peroxidase or catalase activities, and do not take up isoniazid. The Y-enzyme reaction is therefore implicated in the uptake of the drug.
01 Feb 1975
TL;DR: A fractional weighted number system, based on Hensel’s code, is proposed for constructing a unique code for rational numbers in a certain range, which combines the best features and advantages of both thep-ary and residue number systems.
Abstract: A fractional weighted number system, based on Hensel’sp-adic number system, is proposed for constructing a unique code (called Hensel’s code) for rational numbers in a certain range. In this system, every rational number has an exact representation. The four basic arithmetic algorithms that use the code for the rational operands, proceed in one direction, giving rise to an exact result having the same code-wordlength as the two operands. In particular, the division algorithm is deterministic (free from trial and error). As a result, arithmetic can be carried out exactly and much faster, using the same hardware meant forp-ary systems.
TL;DR: The present study indicates that the nonplanar distortions at the nitrogen atom of the peptide unit may have to be taken into consideration, in addition to the variation in the dihedral angles (ϕ,ψ), in working out polypeptide and protein structures.
Abstract: The possible nonplanar distortions of the amide group in formamide, acetamide, N-methylacetamide, and N-ethylacetamide have been examined using CNDO/2 and INDO methods. The predictions from these methods are compared with the results obtained from X-ray and neutron diffraction studies on crystals of small open peptides, cyclic peptides, and amides. It is shown that the INDO results are in good agreement with observations, and that the dihedral angles N and defining the nonplanarity of the amide unit are correlated approximately by the relation N = -2 , while C is small and uncorrelated with . The present study indicates that the nonplanar distortions at the nitrogen atom of the peptide unit may have to be taken into consideration, in addition to the variation in the dihedral angles ( , ), in working out polypeptide and protein structures.
TL;DR: It is suggested that by using antisera raised in humans to ovine LH, this method may be developed as a fertility control measure in humans.
TL;DR: In this paper, the authors investigated the thermal decomposition of strontium titanyl oxalate tetrahydrate (SITO) and calcium titanyl Oxalate hexahydrate using TG, DTA, gas and chemical analysis.
01 Apr 1975
TL;DR: In this paper, the peristaltic motion of a micropolar fluid is studied for small amplitudes of peristalic waves under low Reynolds number analysis, and the effect of pressure gradient on the secondary motion reveals many interesting and useful results.
Abstract: Peristaltic motion of a micropolar fluid is studied for small amplitudes of peristalic waves under low Reynolds number analysis. The effect of pressure gradient on the secondary motion reveals many interesting and useful results. The critical value of the pressure gradient ensuing the reversal effect in both velocity field and microrotation is evaluated and discussed.
TL;DR: In this paper, the vanadyl ion was analyzed in paramagnetically dilute form in K2Zn(SO4)2·6H2O and K2Mg(SO 4)2 ·6H 2O at room temperature at X-band.
TL;DR: In this paper, the similarity solution for the steady incompressible laminar boundary layer flow of a micropolar fluid past an infinite wedge was presented, and the governing equations have been solved numerically using fourth order Runge-Kutta-Gill method.
Abstract: This paper presents the similarity solution for the steady incompressible laminar boundary layer flow of a micropolar fluid past an infinite wedge. The governing equations have been solved numerically using fourth orderRunge-Kutta-Gill method. The results indicate the extent to which the velocity and microrotation profiles, and the surface shear stress are influenced by coupling, microrotation, and pressure gradient parameters. The important role played by the standard length of the micropolar fluid in determining the structure of the boundary layer has also been discussed.
TL;DR: In this paper, the thermal decomposition of barium titanyl oxalate has been studied and the sigmoidal (α, t) curves obey a power law equation followed by first order decay.
TL;DR: Characterization indicated six different types of Pseudomonas strains, one of which belonged to the genus Alcaligenes hitherto never reported to degrade oxalate, which differed physiologically from strains already known.
Abstract: Forty-one cultures degrading and assimilating oxalate were isolated from chicken dung Characterization indicated six different types One of these belonged to the genusAlcaligenes hitherto never reported to degrade oxalate Three groups ofPseudomonas strains differed physiologically from strains already known
TL;DR: In this article, the thermal decomposition of ammonium perchlorate (AP) in cubic modification has been studied in the temperature range 300-390°C and two distinct regions of temperature dependence are observed for the rate constants of the decomposition.
TL;DR: The root and shoot portions of the embryo-axis also exhibited a similar relationship between changes in DNA, RNA and protein and all the above amines during development, however, the polyamine content of the shoots was relatively higher than those of the roots during the growth period.
01 Nov 1975
TL;DR: Computer procedures are described for error-free matrix computations, using thep-adic arithmetic, and the exact solution of a highly ill-conditioned linear system of equations is obtained by using the Gaussian elimination method.
Abstract: Computer procedures are described for error-free matrix computations, using thep-adic arithmetic. As an example, the exact solution of a highly ill-conditioned linear system of equations is obtained, by using the Gaussian elimination method.
TL;DR: The binding of chromomycin A3, an antitumour antibiotic, to various DNA and chromatin isolated from mouse and rat liver, mouse fibrosarcoma and Yoshida ascites sarcoma cells was studied spectrophotometrically and differences may be taken to indicate structural difference in nucleoprotein complexes caused by neoplasia.
TL;DR: It is suggested that LH plays a critical role in the maintenance of CL of early pregnancy in the hamster and that deprivation of LH, even for periods as short as 3 h, significantly influences steroid production.
Abstract: The effect of luteinizing hormone antiserum (LH A/S) on sterol and steroid levels in luteal and non-luteal ovarian compartments, and on serum steroid levels of pregnant hamsters, was studied Injection (ip) of 01 ml of LH A/S on day 7 caused termination of pregnancy and morphological regression of the corpus luteum (CL) within 18-20 h of treatment, whereas LH-free non-immune serum had no effect Within 3 h of administration of LH A/S the luteal progesterone levels fell from a control value of 360 +/- 24 to 156 +/- 34 ng/mg, and estrogen from a control value of 208 +/- 34 to 122 +/- 15 pg/mg By 12 h progesterone had dropped to 73 +/- 03 ng/mg whereas estrogen was undetectable by radioimmunoassay Serum progesterone fell in 3 h from 553 +/- 039 to 315 +/- 026 ng/ml whereas estrogen fell from 172 +/- 26 to 123 +/- 9 pg/ml The progesterone content of non-luteal ovarian tissue dropped in 3 h from 106 +/- 001 to 047 +/- 006 ng/mg and estrogen from 1150 +/- 15 to 110 +/- 065 pg/mg Both progesterone and estrogen were undetectable at 24 h In the CL, free cholesterol concentration did not change significantly after A/S treatment, while esterified cholesterol increased from 282 +/- 014 to 414 +/- 025 mug/mg within 6 h and 552 +/- 017 mug/mg by 12 h The results suggest that LH plays a critical role in the maintenance of CL of early pregnancy in the hamster and that deprivation of LH, even for periods as short as 3 h, significantly influences steroid production The accumulation of cholesterol esters following LH-deprivation suggests that loss of cholesteryl esterase activity could be one of the events leading to luteolysis