Showing papers by "Indian Institute of Science published in 1974"
01 Jul 1974
TL;DR: Attention has been focused on the norms of behavior of learning automata, issues in the design of updating schemes, convergence of the action probabilities, and interaction of several automata.
Abstract: Stochastic automata operating in an unknown random environment have been proposed earlier as models of learning. These automata update their action probabilities in accordance with the inputs received from the environment and can improve their own performance during operation. In this context they are referred to as learning automata. A survey of the available results in the area of learning automata has been attempted in this paper. Attention has been focused on the norms of behavior of learning automata, issues in the design of updating schemes, convergence of the action probabilities, and interaction of several automata. Utilization of learning automata in parameter optimization and hypothesis testing is discussed, and potential areas of application are suggested.
688 citations
TL;DR: It is shown that the antifungal drug alters the cellular permeability, and thus the exogenous respiration becomes sensitive to the drug.
Abstract: The antifungal drug, miconazole nitrate, inhibits the growth of several species of Candida. Candida albicans, one of the pathogenic species, was totally inhibited at a concentration of approximately 10 μg/ml. Endogenous respiration was unaffected by the drug at a concentration as high as 100 μg/ml, whereas exogenous respiration was markedly sensitive and inhibited to an extent of 85%. The permeability of the cell membrane was changed as evidenced by the leakage of 260-nm absorbing materials, amino acids, proteins, and inorganic cations. The results we present clearly show that the drug alters the cellular permeability, and thus the exogenous respiration becomes sensitive to the drug.
129 citations
TL;DR: The ratio kf/kd (43μM −1), that corresponds to the association constant of complex RC1· ConA4, is higher than that of mannoside · ConA 4 and thereby suggests that protein-protein interaction contributes significantly in stabilising glycoprotein · lectin complexes.
Abstract: A galactose-specific protein (RC1) isolated from Ricinus communis beans was found to give a precipitin reaction with concanavalin A. Its carbohydrate content amounted to 8–9% of the total protein and was found to be rich in mannose. The interaction of RC1 with galactose and lactose was measured in 0.05 M phosphate buffer containing 0.2 M NaCl (pH 6.8) by the method of conventional equilibrium dialysis. From the analysis of the binding data according to Scatchard method the association constant (Ka) at 5°C was calculated as 3.8 mM−1 and 1.2 mM−1 for lactose and galactose, respectively. In both cases the number of binding sites per molecule of RC1 with molecular weight of 120000 was found to be 2. From the temperature-dependent Ka values for the binding of lactose, the values of –5.7 kcal/mol and –4.3 cal × mol−1× K−1 were calculated for ΔH and ΔS, respectively.
The addition of concanavalin A to RC1 or vice versa led to the formation of the insoluble complex RC1· ConA4 containing one molecule of RC1 and one molecule of tetrameric concanavalin A (ConA4) which could be dissociated upon addition of concanavalin A-specific sugars. The complex formation results in a time-dependent appearance of turbidity in the time range from 10s to 10 min. From the measurement of the time-dependent appearance and disappearance of the turbidity the formation (kf) and dissociation (kd) rate constants were calculated as 3 mM−1× s−1 and 0.07 ks−1 respectively. The ratio kf/kd (43μM −1), that corresponds to the association constant of complex RC1· ConA4, is higher than that of mannoside · ConA4 and thereby suggests that protein-protein interaction contributes significantly in stabilising glycoprotein · lectin complexes. The relevance of this finding to the understanding of the chemical specificities that are involved in a model cell-lectin interaction is discussed.
101 citations
TL;DR: In this paper, wear rates of cast graphitic aluminium-silicon-nickel alloys were lower than those of pure Al, Al-Si and AlSi-Ni alloys especially above pressures of 0.02 kg/mm2.
94 citations
TL;DR: In this paper, the seizure resistance of several cast aluminium base alloys has been examined using a standard Hohman Wear Tester, and it was shown that a slight increase in the solute content or the hardness of the primary α-phase leads to a considerable increase in seizure resistance.
68 citations
TL;DR: It was concluded that the dietary phosphatidylcholine is hydrolysed in the intestinal lumen by the pancreatic phospholipase A to 1-acylglycerylphosphorylcholine, which on entering the mucosal cell is partly reacylated to phosphate, and the rest is further Hydrolysed to glycerylPhosphorycholine.
Abstract: 1. The mechanism of absorption of phosphatidylcholine was studied in rats by injecting into the intestine phosphatidylcholine specifically labelled either in the fatty acid or in the glycerol moiety or with 32P, when considerable amounts of 1-acyl-lysophosphatidylcholine were found in the intestinal lumen. 2-([14C]Acyl)phosphatidylcholine gave markedly more radioactive unesterified fatty acids in the lumen, compared with the 1-([14C]acyl) derivative. Some of the radioactivity from either the fatty acid or the glycerol moiety of the injected phosphatidylcholine appeared in the mucosal triacylglycerols. 2. Injection of 32P-labelled phosphatidylcholine or 32P-labelled lysophosphatidylcholine led to the appearance of radioactive glycerylphosphorylcholine, glycerophosphate and Pi in the mucosa. 3. Rat mucosa was found to contain a highly active glycerylphosphorylcholine diesterase. 4. It was concluded that the dietary phosphatidylcholine is hydrolysed in the intestinal lumen by the pancreatic phospholipase A to 1-acylglycerylphosphorylcholine, which on entering the mucosal cell is partly reacylated to phosphatidylcholine, and the rest is further hydrolysed to glycerylphosphorylcholine, glycerophosphate, glycerol and Pi. The fatty acids and glycerophosphate are then reassembled to give triacylglycerols via the Kennedy (1961) pathway.
67 citations
TL;DR: A study of probability distribution function and spectrum of the Airborne total intensity map for an area of 3000 Squ. miles covered by the Bundelkhand granite in India has revealed a close correlation between the Gaussian or non-Gaussian nature of distribution and the shape of the unite value contour on the spectrum plot.
Abstract: A study of probability distribution function and spectrum of the Airborne Total Intensity Map for an area of 3000 Squ. miles covered by the Bundelkhand granite in India has revealed a close correlation between the Gaussian or non-Gaussian nature of distribution and the shape of unite value contour on the spectrum plot. Further studies of radial spectrum plots suggest that the surface magnetic sources are mainly responsible for the non-Gaussian character of the distribution function and as well as for irregular spectrum shape. The histogram of depth values for magnetic sources obtained from radial spectrum plots show three horizons, namely (i) surface (ii) 410 m(1400′) and (iii) 1000 m (3400′). Based on these informations blocks with ferromagnetic composition at the surface can be identified from those which are non magnetic at the surface.
60 citations
TL;DR: The average dimensions of the peptide unit have been obtained from the data reported in recent crystal structure analyses of di- and tripeptides, and these mean values as observed in crystal structures are relevant for model building of peptide chain structures.
57 citations
TL;DR: In this article, the authors measured the static pressure distribution in the separated flow region behind backward-facing steps in a wind tunnel, suitable corrections were applied for the model blockage, which indicated a reasonably well defined similarity in the pressure distribution.
Abstract: Static pressures have been measured in the separated flow region behind backward-facing steps in a wind tunnel, suitable corrections being applied for the model blockage. The results indicate a reasonably well defined similarity in the pressure distribution.
51 citations
01 Sep 1974
TL;DR: In this article, the authors derived the governing equations from the three-dimensional elasticity equations using a MacLaurin series approach, which can be obtained in the form of series and approximate theories of any desired order can be constructed easily by proper truncation.
Abstract: Thick rectangular plates are investigated using the method of initial functions proposed by Vlasov. The governing equations are derived from the three-dimensional elasticity equations using a MacLaurin series approach. As the governing equations can be obtained in the form of series, approximate theories of any desired order can be constructed easily by proper truncation. An exact solution is obtained for an allround simply supported thick plate using a Navier type solution. A Levy type solution for higher order theories is illustrated for the case of a thick plate with two opposite edges simply supported and other two edges clamped. Numerical results obtained are compared with those of classical, Reissner and Srinivas et al. solutions.
50 citations
TL;DR: It has been conclusively shown for the first time that mono-ring substituted carotenoids are also cleaved at the 15,15′-double bond in guinea pig and rabbit enzyme.
TL;DR: In this article, the classical Rayleigh-Ritz method in conjunction with suitable co-ordinate transformations is found to be effective for accurate estimation of natural frequencies of circumferentially truncated circular sector plates with simply supported straight edges.
TL;DR: “Strong” excitants of central neurones such as β N-oxalyl L α,β-diaminopropionic acid, N-methyl-D-aspartic acid, and kainic acid were found to inhibit the high affinity uptake of glutamate and aspartate in synaptosomes isolated from young rat brain.
TL;DR: In this article, a new set of equations describing completely the optical phenomena in a model involving continuous rotation of secondary axes and secondary principal-stress differences are obtained by using the Peano-Baker method.
Abstract: A new set of equations describing completely the optical phenomena in a model involving continuous rotation of secondary axes and secondary principal-stress differences are obtained. These are solved by Peano-Baker method using experimentally determined characteristic parameters for several wavelengths of light. Experimental verifications are obtained for a rectangular bar subjected to combined torsion and tension.
TL;DR: A simple procedure for the state minimization of an incompletely specified sequential machine whose number of internal states is not very large is presented and the concept of a compatibility graph from which the set of maximal compatibles of the machine can be very conveniently derived is introduced.
Abstract: A simple yet efficient method for the minimization of incompletely specified sequential machines (ISSM's) is proposed. Precise theorems are developed, as a consequence of which several compatibles can be deleted from consideration at the very first stage in the search for a minimal closed cover. Thus, the computational work is significantly reduced. Initial cardinality of the minimal closed cover is further reduced by a consideration of the maximal compatibles (MC's) only; as a result the method converges to the solution faster than the existing procedures. "Rank" of a compatible is defined. It is shown that ordering the compatibles, in accordance with their rank, reduces the number of comparisons to be made in the search for exclusion of compatibles. The new method is simple, systematic, and programmable. It does not involve any heuristics or intuitive procedures. For small- and medium-sized machines, it can be used for hand computation as well. For one of the illustrative examples used in this paper, 30 out of 40 compatibles can be ignored in accordance with the proposed rules and the remaining 10 compatibles only need be considered for obtaining a minimal solution.
TL;DR: It is shown that ODAP does not inhibit the glutamate uptake by the high affinity system, which is significant in view of the neurotransmitter function of glutamate, which seems to be neuroexcitory as well as neurotoxic.
Abstract: THE unusual amino acid β-N-oxalyl-L-α, β-diaminopropionic acid (ODAP), isolated from the seeds of Lathyrus sativus is a potent neurotoxin1–3. It produces biochemical changes in the brain typical of an excitant amino acid and is implicated in the aetiology of human neurolathyrism caused by eating the seeds of L. sativus4–6. It may act as a glutamate antagonist: ODAP inhibits glutamate oxidation7 possibly by inhibiting glutamate uptake in bovine brain mitochondria; it also acts as a competitive inhibitor of glutamate uptake in certain strains of yeast8, and a similar process might occur at the synaptic level. Any effect of ODAP on glutamate uptake at synapses is significant in view of the neurotransmitter function of glutamate, which seems to be neuroexcitory as well as neurotoxic9–12. But Balcar and Johnston13 have shown with rat brain slices that ODAP does not inhibit the glutamate uptake by the high affinity system.
TL;DR: In this article, the rotational effects of stressed photoelastic medium can be determined experimentally using a linear retarder model with a pure rotator of power 2 and the principal axis at azimuth 1.
Abstract: Any stressed photoelastic medium can be reduced to an optically equivalent model consisting of a linear retarder, with retardation 1 and principal axis at azimuth 1, and a pure rotator of power 2. The paper describes two simple methods to determine these quantities experimentally. Further, a method is described to overcome the problem of rotational effects in scattered-light investigations. This new method makes use of the experimentally determined characteristic parameters
TL;DR: The main results of the X-ray crystallographic investigations of the cyclic tripeptides L-Pro-L-Pro -L- pro and L- pro-L -Pro- L-Hyp (hereafter called CTP 1 and CTP 2) are reported.
Abstract: MANY cyclic peptides have interesting biological functions and the details of their molecular structure and conformation have been the subject of extensive investigations. Cyclic dipeptides such as diketopiperazine have been synthesised and shown to occur with the peptide units in the cis configuration1,2. In the case of a tripeptide, cyclisation can take place only if all three units are in the cis configuration3. In cyclic peptides with four units also, cis peptides are found4,5. As the number of the peptide units increases, the more stable trans configuration is generally more common6,7. We report here the main results of our X-ray crystallographic investigations of the cyclic tripeptides L-Pro-L-Pro-L-Pro and L-Pro-L-Pro-L-Hyp (hereafter called CTP 1 and CTP 2, respectively). CTP 1 was synthesised by Rothe et al. 8 and its derivatives have been prepared by Blout and his collaborators9.
TL;DR: Governing equations in the form of simultaneous ordinary differential equations have been derived for natural vibration analysis of isotropic laminated beams as mentioned in this paper, which includes significant secondary effects such as transverse shear and rotatory inetia.
TL;DR: In this article, a parallel reaction scheme was used to form maleic anhydride and carbon dioxide from furfural by using vanadium pentoxide catalyst in an isothermal flow reactor in the temperature range of 220-280°C.
TL;DR: In this paper, the authors generalized the Marcinkiewicz theorem to probability distribution functions of many variables and probability distribution functionals when the stochastic variables are both commuting and anticommuting (Fermi).
Abstract: The Marcinkiewicz theorem states that the characteristic function of a probability distribution function cannot be an exponential of a polynomial of degree larger than 2. This theorem is generalized in the present paper to (i) probability distribution functions of many variables and to (ii) probability distribution functionals when the stochastic variables are both commuting (Bose) and anticommuting (Fermi). The consequences of this theorem to certain approximation schemes in many-particle physics, involving truncation of hierarchical equations, are pointed out. These follow when one observes that the hierarchical equations such as those of many-particle Green's functions can be generated from a single equation for a Green's functional whose structure is that of a characteristic functional of a probability distribution functional. The theorem implies that this would exhibit a nonpositive behavior when certain truncation schemes are employed. Specific examples illustrating our results are drawn from the theory of an electron gas, turbulence theory, and quantum optics.
TL;DR: In this paper, a reasonably quantitative explanation for the grain size dependence of apparent activation volume measurements is given for polycrystalline cadmium as an example and by utilizing the predicted temperature or strain rate-dependence of the (Hall-Petch) stress-grain size parameters.
Abstract: Taking polycrystalline cadmium as an example and by utilizing the predicted temperature or strain rate-dependence of the (Hall-Petch) stress-grain size parameters, a reasonably quantitative explanation is given for the grain size dependence of apparent activation volume measurements. The explanation involves the theoretical relation of these measurements to single-crystal measurements.
01 Mar 1974
TL;DR: In this paper, the optimal maintenance policies for a machine with degradation in performance with age and subject to failure are considered, and the optimal policies are generally of a bang-coast nature, except in the case where the probability of machine failure is a function of maintenance.
Abstract: Optimal maintenance policies for a machine with degradation in performance with age and subject to failure are considered. The optimal policies are shown to be generally of a bang-coast nature, except in the case where the probability of machine failure is a function of maintenance. It is also shown, in the case where machine failure is not taken into account, that a high depreciation rate tends to reverse this policy to coast-bang. The results obtained here extend and unify the recent results for this problem.
TL;DR: In this article, the presence of 2-methylthioribosylzeatin in 35S labled nucleosides prepared from tRNA of Pseudomonas aeruginosa by phosphocellulose column chromatography and thin layer chromatography was revealed.
TL;DR: In this paper, the CS2 + CH3NO2 system showed Iµ=0.315±0.004 over 10-6
Abstract: The system CS2 + CH3NO2 shows I²=0.315±0.004 over 10-6
TL;DR: It is demonstrated, by means of the membrane-filtration assay, that anti-isopentenyladenosine antibodies produced by the ;periodate procedure' are much more reactive with the periodate-oxidized form of the nucleoside than with the parent compound.
Abstract: The method of conjugation of a nucleoside or related compound to a carrier protein may have a significant effect on the specificity of the antibodies elicited. It is demonstrated, by means of the membrane-filtration assay, that anti-isopentenyladenosine antibodies produced by the `periodate procedure' are much more reactive with the periodate-oxidized form of the nucleoside than with the parent compound. In addition, the simplicity and specificity of the assay used suggests its use as a sensitive radioimmunoassay for this multifunctional nucleoside.
TL;DR: The antitumour protein from the α-endotoxin of Bacillus thuringiensis var.
TL;DR: Rat brain particulate fractions were shown to acylate [32P]1‐alkyl‐sn‐glycero‐3‐phosphorylethanolamine (GPE) and the acyl transferase activity was completely dependent on added ATP and CoA and it was localized mainly in the microsomal fraction.
Abstract: Rat brain particulate fractions were shown to acylate [32P]1-alkyl-sn-glycero-3-phosphorylethanolamine (GPE). While the main product is 1-alkyl-2-acyl GPE, about 12 per cent of the radioactivity was also found in 1-alkenyl-2-acyl GPE. The acyl transferase activity was completely dependent on added ATP and CoA and it was localized mainly in the microsomal fraction. A comparative study of acyl transferase activities to 1-alkyl-, 1-alkenyl-, and 1-acyl GPE by crude mitochondrial fraction and microsomes of 10, 16 and 22-day-old rat brains showed a progressive increase in activity with development. In the 22-day-old rat brain the order of activity towards the three substrates is as follows: 1-acyl GPE ± 1-alkenyl GPE ± 1-alkyl GPE with a crude mitochondrial fraction and 1-acyl GPE ± 1-alkyl GPE ± 1-alkenyl GPE with microsomes.
01 Nov 1974
TL;DR: Optimal preventive maintenance policies, for a machine subject to deterioration with age and intermittent breakdowns and repairs, are derived using optimal control theory and are shown to be of bang-bang nature.
Abstract: Optimal preventive maintenance policies, for a machine subject to deterioration with age and intermittent breakdowns and repairs, are derived using optimal control theory. The optimal policies are shown to be of bang-bang nature. The extension to the case, when there are a large number of identical machines and several repairmen in the system, is considered next. This model takes into account the waiting line formed at the repair facility and establishes a link between this problem and the classical 'repairmen problem'. An example is presented in detail illustrating, the procedure to obtain the optimal maintenance policy and the optimum number of repairmen for a system consisting of two machines. The results obtained here extend and unify several recent results for the problem.