Showing papers by "Jawaharlal Nehru University published in 1989"
TL;DR: This work defines a variant of the model of Bak, Tang, and Wiesenfeld of self-organized critial behavior by introducing a preferred direction and characterize the critical state and determines the critical exponents exactly in arbitrary dimension d.
Abstract: We define a variant of the model of Bak, Tang, and Wiesenfeld of self-organized critial behavior by introducing a preferred direction. We characterize the critical state and, by establishing equivalence to a voter model, determine the critical exponents exactly in arbitrary dimension d. The upper critical dimension for this model is three. In two dimensions the model is equivalent to an earlier solved special case of directed percolation.
232 citations
TL;DR: In this paper, the authors discuss the role of the colonial experience in the growth and acceptance of what are called communal ideologies in post-colonisation Indian society and the need for a continuing dialogue between historians working on these periods.
Abstract: My choice of subject for this lecture arose from what I think might have been a matter of some interest to Kingsley Martin; as also from my own concern that the interplay between the past and contemporary times requires a continuing dialogue between historians working on these periods. Such a dialogue is perhaps more pertinent to post-colonial societies where the colonial experience changed the framework of the comprehension of the past from what had existed earlier: a disjuncture which is of more than mere historiographical interest. And where political ideologies appropriate this comprehension and seek justification from the pre-colonial past, there, the historian's comment on this process is called for. Among the more visible strands in the political ideology of contemporary India is the growth and acceptance of what are called communal ideologies. ‘Communal’, as many in this audience are aware, in the Indian context has a specific meaning and primarily perceives Indian society as constituted of a number of religious communities. Communalism in the Indian sense therefore is a consciousness which draws on a supposed religious identity and uses this as the basis for an ideology. It then demands political allegiance to a religious community and supports a programme of political action designed to further the interests of that religious community. Such an ideology is of recent origin but uses history to justify the notion that the community (as defined in recent history) and therefore the communal identity have existed since the early past.
201 citations
TL;DR: Results demonstrated that S. cerevisiae became more resistant to ethanol with an increase in the degree of unsaturation and that membrane fluidity could be an important determinant of ethanol tolerance.
Abstract: The effect of ethanol on exponential phase cultures of S. cerevisiae has been examined using l-alanine uptake and proton efflux as indices of ethanol tolerance. Preincubation with 2 M ethanol inhibited l-alanine uptake, proton efflux and fermentation rates. However, the effect of ethanol varied in yeast cells enriched with different fatty acyl residues. It was observed that cells enriched with polyunsaturated fatty acids acquired greater tolerance to ethanol as compared to monounsaturated fatty acids. By varying the degree of unsaturation of supplemented fatty acid, a sequential insertion of double bonds in yeast membrane lipid was achieved. Results demonstrated that S. cerevisiae became more resistant to ethanol with an increase in the degree of unsaturation and that membrane fluidity could be an important determinant of ethanol tolerance.
137 citations
TL;DR: In this article, the toxicity of heavy metals on photosystem 2 photochemistry was investigated by monitoring Hill activity, fluorescence, and thermoluminescence properties of pea (Pisum sativum L. cv. QB) chloroplasts.
Abstract: The toxicity of heavy metals on photosystem 2 photochemistry, was investigated by monitoring Hill activity, fluorescence, and thermoluminescence properties of photosystem 2 (PS 2) in pea (Pisum sativum L. cv. Bombay) chloroplasts. In Co2+-, Ni2+- or Zn2+-treated chloroplasts 2,6-dichlorophenolindophenol-Hill activity was markedly inhibited. Addition of hydroxylamine which donates electrons close to PS 2 reaction center did not restore the PS 2 activity. Co2+-, Ni2+ or Zn2+ also inhibited PS 2 activity supported by hydroxylamine in tris (hydroxymethyl)aminomethane (Tris)-inactivated chloroplasts. These observations were confirmed by fluorescence transient measurements. This implies that the metal ions inhibit either the reaction center or the components of PS 2 acceptor side. Flash-induced thermoluminescence studies revealed that the S2Q−A charge recombination was insensitive to metal ion addition. The S2Q−B charge recombination, however, was inhibited with increase in the level of Co2+, Ni2+ or Zn2+. The observed sensitivity of S2−B charge recombination in comparison to the stability of S2Q−A recombination suggests that the metal ions inhibit at the level of secondary quinone electron acceptor. QB. We suggest that Co2+, Ni2+ or Zn2+ do not block the electron flow between the primary and secondary quinone electron acceptor, but possibly, directly modify QB site, leading to the loss of PS 2 activity.
121 citations
TL;DR: The history of accretion of discrete crustal terranes resembles those of Phanerozoic convergent margins and thus suggests that plate tectonics operated on Earth by 2500 Ma.
Abstract: The Archean Kolar Schist Belt, south India, is a suture zone where two gneiss terranes and at least two amphibolite terranes with distinct histories were accrted. Amphibolites from the eastern and western sides of the schist belt have distinct incompatible element and isotopic characteristics sugesting that their volcanic protoliths were derived from dint mantle sources. The amphibolite and gneiss terranes were juxtaposed by horizontal compression and shearing between 2530 and 2420 million years ago (Ma) along a zone marked by the Kolar Schist Belt. This history of accretion of discrete crustal terranes resembles those of Phanerozoic convergent margins and thus suggests that plate tectonics operated on Earth by 2500 Ma.
91 citations
TL;DR: The multiple copies of the beta-lactamase gene do not seem to be present on a single chromosome, as evident from the fragment obtained by digestion of cellular DNA with the appropriate restriction endonuclease, which indicates the presence of multiple chromosomes in A. vinelandii.
Abstract: The number of copies of the genes leuB, nifH, nifD, and nifK per cell of Azotobacter vinelandii has been determined to be about 80. A beta-lactamase gene was integrated into the A. vinelandii chromosome by single-point crossover. Subsequently, we have been able to detect nearly 80 copies of this beta-lactamase gene per cell of A. vinelandii when cultured for a large number of generations in the presence of ampicillin. The multiple copies of the beta-lactamase gene do not seem to be present on a single chromosome, as evident from the fragment obtained by digestion of cellular DNA with the appropriate restriction endonuclease. The kinetics of renaturation of DNA of A. vinelandii is suggestive of complexity similar to that of Escherichia coli. The DNA content of A. vinelandii, however, is 40 times that of E. coli. All these indicate the presence of multiple chromosomes, possibly as many as 80, in A. vinelandii.
69 citations
66 citations
TL;DR: The results suggest that the Re-Os system may have only limited utility for geochronologic applications in regions for which postcrystallization noble metal mineralization is evident as discussed by the authors.
60 citations
TL;DR: According to the National Energy Plan (NERP), annual production of 1.2 × 109 t by 1989 and 1.91 × 109 T by the year 2000 are anticipated as mentioned in this paper, which appears reasonable to expect an increase in the percentage as well as the number of coal-fired power plants.
Abstract: Among traditional fossil fuel sources, coal exists in quantities capable of supplying a large portion of our future energy needs. According to the President's National Energy Plan, annual productions of 1.2 × 109 t by 1989 and 1.91 × 109 t by the year 2000 are anticipated. It appears reasonable to expect an increase in the percentage as well as the number of coal‐fired power plants. The increased use of coal will produce additional quantities of fly ash, one of the waste products of burning pulverized coal. Fly ash constitutes about 70% of the total amount of residue generated in coal‐fired power plants equipped with electrostatic precipitators or bag filters. Fly ash contains various substances of which trace metals, although present in a small fraction, are of special interest due to their cumulative build up, long life, and high toxicity to man, plants, and animals through air, water, and soil. Several estimates made by the Bureau of Mines suggest that the fly ash released into the atmosphere appears t...
59 citations
TL;DR: The structural and nt homologies between the two Clc operons, tfdCDEF and clcABD, suggest their relatedness and the predicted N-terminal aa sequences of the two hydrolase-encoding genes, t FDD and tfdE, show homology.
49 citations
TL;DR: The inhibition of genotoxicity by coffee was observed in bone-marrow cells sampled 24, 48 or 68 hr after injecting cyclophosphamide, and Freshly brewed coffee extract, standard instant coffee, decaffeinated instant coffee and freeze-dried home-brew coffee all exerted inhibitory effects.
TL;DR: In this paper, it was shown that copper inhibits chlorophyll variable fluorescence (F v ) at room temperature in the presence and absence of DCMU, with the apparent I 50 value being 25 μM and 30% of F v remains insensitive to copper at a concentration which inhibits electron transport completely.
TL;DR: Leaf extracts and leaf leachates ofProsopis juliflora and Prosopis cineraria showed the allelopathic compounds to be phenolic in nature in both the species, suggesting accumulation of toxic substances in soil layers, inhibiting growth of other species.
Abstract: The allelopathic effects ofProsopis juliflora were studied both in the laboratory and in nature and compared with that ofProsopis cineraria to understand the chemical nature of allelochemics. Both species occupy the same habitats butP. cineraria does not appear to have any toxic effect on other plants under its canopy.P. juliflora is highly allelopathic and does not allow the growth of any other species. Leaf extracts and leaf leachates ofP. juliflora were inhibitory. Decaying leaves were also inhibitory at early stages of decomposition. Live roots were not found to be inhibitory in cogermination and interplanting of seeds. Chemical investigation of the extracts showed the allelopathic compounds to be phenolic in nature in both the species. Slow decomposition and heavy accumulation of leaf litter belowP. juliflora may possibly result in accumulation of toxic substances in soil layers, inhibiting growth of other species.
TL;DR: In this paper, the authors compare migration of talent to brain drain and conclude that India does not completely lose its investment in education when professionals migrate since the migrants still contribute to knowledge and also send remittances to relatives in India.
Abstract: 2 views on "brain drain" exist: 1) LDCs lose their enormous investments on higher education when skilled people migrate to other countries and 2) LDCs are exaggerating the problem and only a few skilled people migrate at 1 time. India does not completely lose its investment in education when professionals migrate since the migrants still contribute to knowledge and also send remittances to relatives in India. Unemployed educated people would cause a greater drain on Indias resources than educated migrants. The author prefers the phrase migration of talent to brain drain since the former indicates a 2-way movement. Most migrants from LDCs are students. About 11000 university graduates leave India every year for advanced study and/or work. A conservative estimate is that 2500 will remain abroad permanently. Most professionals who migrate go to the US and Canada. Factors promoting migration include 1) unemployment 2) immigration rules 3) colonial links 4) financial incentives and material benefits 5) pursuit of higher education 6) improvement of working conditions and facilities 7) avoidance of excessive bureaucratic procedures and 8) compensation for the mismatch between Indian education and employment. Reasons for returning to India include 1) deference to wives who were unable to adjust to a foreign way of life 2) contributing to Indian development and 3) racial discrimination. It will probably not be possible to lure back migrants who left for material reasons. Attractive job offers could entice back those who left for advanced training. To encourage the return of those who left to pursue high quality research India must 1) increase expenditure on research and development possibly through the private industrial sector 2) promote travel to other countries for professional enrichment and 3) improve conditions of research work. The article concludes with an analysis of migration of talent from 3 perspectives: 1) the individual 2) the nation-state and 3) the world as a whole.
TL;DR: In this paper, water quality of the snout of the Chhota-Shigri glacier, Eastern Lahul Valley, India, was analyzed for major cations and anions.
TL;DR: In this article, the composition of bed, core and suspended sediments collected from Krishna River sediments were studied and the observations are discussed in the light of other Indian rivers, world's average river suspended particles, surficial rock and soils.
TL;DR: Only unprocessed areca nuts, at high doses, displayed a very weak carcinogenicity, while the other preparations, including ripe‐uprocessedsundried nut and ripe‐unprocessed‐undried‐water‐soaked nut, displayed very weak cancericity.
Abstract: Areca nut has been used as a masticatory since antiquity and it is estimated that more than 10% of the world population chews it in a variety of forms. We have evaluated the carcinogenicity of different preparations of areca nut: ripe-unprocessed-sundried nut (R-UP-SD), ripe-processed-sundried nut (R-P-SD), unripe-processed-sundried nut (UR-P-SD), ripe-unprocessed-sundried-water-soaked nut (R-UP-SD-WS) and ripe-unprocessed-undried-water-soaked nut (R-UP-UD-WS) in mice following diet-feeding or oral feeding for 12 months. Only unprocessed areca nuts (R-UP-SD, R-UP-SD-WS and R-UP-UD-WS), at high doses, displayed a very weak carcinogenicity.
TL;DR: In this article, Narayanaswami et al. studied the Kolar schist belt and found that the sulfide lodes contain 5 to 30 vol percent sulfides which include dominantly pyrrhotite and arsenopyrite.
Abstract: The Kolar schist belt, one of the auriferous Archean schist belts in the Dharwar craton, includes two types of gold deposits: (1) a stratiform sulfide type, associated with amphibolites and banded ferruginous quartzite, and (2) a gold quartz-carbonate vein type associated with light rare earth element (LREE)-enriched komatiitic and tholeiitic amphibolites on the eastern part of the belt. Many lodes of the former are banded and show deformation similar to that of their host rocks. The latter type consists of veins localized within shear zones. Both types have only a few inches of altered border rock characterized dominantly by biotite with minor diopside and garnet.The sulfide lodes contain 5 to 30 vol percent sulfides which include dominantly pyrrhotite and arsenopyrite. The lodes also contain variable amounts of magnetite and ilmenite. No systematic variation in ore minerals is discernible among the lodes of the entire belt. However, in the Kolar gold fields area, a set of four parallel sulfide lodes exhibit certain textural and mineralogical zoning. Ore minerals show metamorphic equilibrium textures and the temperature of final equilibration of sulfides is 500 degrees C or higher.Sulfide lodes have low but variable abundances of base metals. No correlation among total sulfide contents, sulfide minerals, and abundances of base metals and gold is observed. Nor is there any geochemical coherence between gold and arsenopyrite in the several lodes studied. Major oxides, particularly Al 2 O 3 , TiO 2 , and K 2 O also show a large variation. The REE abundances of the sulfide lodes vary widely, but their patterns are similar, with enrichment in both light REE and heavy REE. Normalized Eu shows strong to negligible enrichment. The REE patterns are similar to those of the banded ferruginous quartzite or iron-formation. Samples with high REE abundances also have high base metals, Al 2 O 3 , TiO 2 , and K 2 O abundances and low arsenopyrite contents. Based on these observations and limited Nd and O isotope data it is suggested that the sulfide lodes were originally auriferous, complex interflow sediments formed from submarine hydrothermal exhalations, seawater, and detrital sediments.The vein-type mineralization has only trace amounts of sulfides with galena as the dominant phase (Narayanaswami et al., 1960). The veins consist dominantly of quartz with minor amounts of calcite and alkali feldspar and trace amounts of scheelite and tourmaline. The gold content of the veins is generally > 10 ppm. The veins are also unusually enriched in Cr and Ni. These observations and the fluid inclusion studies on vein quartz (Santosh, 1986) suggest the presence of CO 2 -bearing ore fluids.One sample of the ore vein has a strongly fractionated, light REE-enriched pattern with an epsilon Nd value of +2.8 at 2,600 Ma. Galena from the ore samples have Pb isotope ratios, reported by Venkatasubramanian et al. (1977) and Chernyshev et al. (1980), that are similar to those of the 2,600-Ma intrusive granodioritic gneisses present on the west side of the schist belt (Krogstad et al., 1989). The delta 18 O of vein quartz is 11.6 + or - 0.7 per mil (Golding, 1982). These geochemical data suggest that the gold quartz veins were formed dominantly from magmatic fluids derived from the crystallization of granitic rocks. A contribution from metamorphic fluids is also conceivable as indicated by the abundance of Ni and Cr in the veins.
TL;DR: Intracellular pH (pHi) was determined during arrest and recovery of temperature sensitive-cell division cycle mutants of Saccharomyces cerevisiae; but when the mutants were released from arrest a rapid increase in pHi ensued in only cdc28- and cdc37-arrested cells.
Abstract: Intracellular pH (pHi) was determined during arrest and recovery of temperature sensitive-cell division cycle mutants of Saccharomyces cerevisiae. In all mutants, pHi decreased during arrest; but when the mutants were released from arrest a rapid increase in pHi ensued in only cdc28- and cdc37-arrested cells. Both of these mutations cause arrest at 'start', the sole regulatory point in the S. cerevisiae cell cycle. In cells with cdc4 or cdc7 mutations, which arrest past start, pHi remained constant and exhibited a decrease, respectively, upon recovery of growth. The activity of plasma membrane ATPase decreased during the first 30 min of recovery of cdc28-arrested cells, concomitant with the rise in pHi. During the same period, there was no significant change in activity in cdc4-bearing cells, whereas an increase was observed for cdc7-bearing cells. Increase in pHi may be used as a specific signal by S. cerevisiae for start traversal and commitment to a new cycle.
TL;DR: In this article, the authors consider the dynamics of defect tunnelling between two trap sites in a metal and calculate the structure factor for inelastic neutron scattering, which is shown to merge into a single quasi-elastic peak at higher temperatures.
Abstract: The authors consider the dynamics of a defect tunnelling between two trap sites in a metal. The interaction with conduction electrons is shown to influence strongly the defect motion at low temperatures. They calculate the structure factor for inelastic neutron scattering. The inelastic scattering peaks found at very low temperatures are shown to merge into a single quasi-elastic peak at higher temperatures. The width of the quasi-elastic peak narrows as the temperature is increased further. This behaviour results from the damping of the defect motion through the non-adiabatic response of the screening cloud. The present paper extends the authors previous results for symmetric two-state systems to the asymmetric case.
TL;DR: The results suggest that amino acids play a regulatory role in Brassica morphogenesis which can be correlated with the activity of threonine deaminase.
Abstract: The effect of amino acids has been investigated with respect to the capacity ofBrassica cultures to undergo proliferation and differentiation. Hormone medium without any amino acid resulted in 6% shoot formation. Addition of optimal concentrations of L-leucine and L-isoleucine enhanced shoot formation upto 30% and 60%, respectively. L-methionine, L-threonine and pyruvic acid supported only proliferation but no differentiation. Amino acids had a marked effect on the activity of enzyme threonine deaminase (TD), bothin vivo andin vitro. TD in proliferating callus cultures was 3-fold higher than in differentiating cultures. Amino acids which induced cell proliferation increased TD while those which supported differentiation repressed it. Amino acids which did not alter TD activity had no effect on morphogenesis. The results suggest that amino acids play a regulatory role inBrassica morphogenesis which can be correlated with the activity of threonine deaminase.
TL;DR: In this article, a trade-off emerges between positive effects of permanent contracts on productivity and the costly seasonal idleness of permanent labour, and conditions are derived for each solution, including the Mirrlees-Bliss-Stern-Stiglitz solution and the Leibenstein-Mazumdar solution.
TL;DR: In this paper, it was shown that exposure of isolated Amaranthus chloroplasts to elevated temperatures (>25 °C for 5 min) induced a stimulation of photosystem I catalyzed electron transport rates only with reduced-dichlorophenolindophenol but not with -tetramethylparaphenylenediamine or -diaminodurene as electron donors.
TL;DR: It is inferred that DHEA inhibits MCA-induced cervical carcinogenesis and the inhibitory action is dependent upon the dose of the drug.
TL;DR: In this article, a model of urbanization based on the "replacement hypothesis" is presented, empirically validated from cross-sectional time-series data from eleven countries and the fits are found to be extremely good.
Abstract: A model of urbanization based on the ‘replacement hypothesis’ is presented. The model is empirically validated from cross-sectional time-series data from eleven countries and the fits are found to be extremely good. Intercountry variations in the growth of urbanization are explained on the basis of the structure of the economy as reflected in the sectoral composition of the national output. The phenomenon of urbanization exhibits remarkable resilience in its growth trajectory. The model is also used to make projections of urbanization for the countries studied.
TL;DR: A significant increase in the GST activity in the liver of mice exposed to BHA or mace was found and there was a significant increase to the SH content in the Liver of mice fed on 1% BHA and 2% mace diets.
TL;DR: The photoreversibility showed that P FR regulates GDH activity in vivo and neither anticalmodulin drugs nor addition of calmodulin had any effect on nitrate re-ductase activity.
Abstract: Regulation by the active form of phytochrome (P FR ) and the effect of Ca 2+ and calmodulin was examined with glutamate dehydrogenase (GDH) of Zea mays. A brief irradiation (5 min) to 5 day old plants with red light resulted in 5-6 fold increase in GDH activity. This effect was nullified when red light was followed immediately by far-red light. The photoreversibility showed that P FR regulates GDH activity in vivo. To the enzyme extract obtained after EGTA treatment, when Ca 2+ was added in vitro, GDH was activated by 6 fold. The maximum response by Ca 2+ was obtained at 80 μM. Both P AR and Ca 2+ effects were found to be age dependent. The enzyme activity was inhibited by compound 48/80 in partially purified extracts and the effect was reversed by calmodulin. The purified GDH, however, was not activated directly by calmodulin; it required the presence of another protein factor which was separated by gel permeation column by HPLC. Neither anticalmodulin drugs nor addition of calmodulin had any effect on nitrate re-ductase activity.
TL;DR: The effects of arecoline on lymphoid organs, which may be due to its direct action or through the elevation of corticosterone, are demonstrated.
Abstract: Arecoline, a suspected carcinogenic/cocarcinogenic alkaloid was screened to explore in detail its immunomodulatory influence in murine model system. The oral LD50 value for male mice was 371 mg/kg bw whereas it was 309 mg/kg bw for female mice. The subcutaneous LD50 value for both sexes was 97 mg/kg bw. Only a marginal difference was observed in intraperitoneal LD50 values between male (120 mg/kg bw) and female (109 mg/kg bw) mice. Arecoline was administered subcutaneously to male mice at subtoxic dose levels (5, 10, and 20 mg/kg bw) for 1, 2 and 3 weeks on a daily basis. In groups where significant decreases in body weight were present (at 20 mg/kg bw for both sexes), reductions in thymus weight were also noted. Spleen, mesenteric lymph nodes (MLN), liver, and kidney showed moderate reductions in their weights. Histopathological effects at 20 mg/kg bw included lymphocyte depletion of the thymic cortex, and the B and T lymphocyte areas in spleen and MLN. In concordance with the zona fasciculate hy...
Journal Article•
TL;DR: In these experiments, BHA has a chemopreventive action against DMBA-induced transplacental and transmammary carcinogenesis in mice and its modulation by butylated hydroxyanisole (BHA) is shown.
Abstract: We discuss the transplacental and transmammary carcinogenicity of 7,12-dimethylbenz[a]anthracene (DMBA) in Swiss albino mice and its modulation by butylated hydroxyanisole (BHA). Transmission of the carcinogen by either route elicits the development of tumour in F1 individuals, and in either situation the incidence of tumours is dependent upon the dose of DMBA administered to gestating or lactating mothers or foster mothers. However, for a given dose of carcinogen, its transplacental carcinogenicity is much greater than its transmammary carcinogenicity. Transmammary carcinogenicity is evident in F1 progeny whether they are nursed by DMBA-exposed mothers, syngenic foster mothers (Swiss albino strain) or allogenic foster mothers (C57BL/6 strain), but the incidence of tumours is appreciably lower when allogenic females are the foster mothers. DMBA administered to females during gestation appears to remain as a residue, then to find its way through the transmammary route into normal F1 individuals being foster-nursed, and to produce tumours. We have also shown the influence of age, but not of parity, of foster mothers on DMBA-induced transmammary carcinogenesis in F1 individuals. In these experiments, BHA has a chemopreventive action against DMBA-induced transplacental and transmammary carcinogenesis in mice.