Showing papers by "Tata Institute of Fundamental Research published in 1976"
130 citations
118 citations
Journal Article•
TL;DR: In this paper, two additional structures on X have been extensively studied: the Riemannian structure and the triangulation of X giving rise to combinatorial or polyhedral topology.
Abstract: Let X be a C ∞ closed manifold of dimension N. Two additional structures on X have been extensively studied. One is the Riemannian structure giving rise to Riemannian geometry and the other is the triangulation of X giving rise to combinatorial or polyhedral topology.
105 citations
Journal Article•
TL;DR: In this article, a Cohen-Macaulay ring is considered and a maximal ideal of height r is defined, i.e., the "blow up" of the ideal I.
Abstract: Let R be a Cohen-Macaulay ring and let M be its maximal ideal. Let 7 be a radical ideal of height r. Let X (= proj ΣI n ) -> Spec R be the "blow up" of the ideal I.
81 citations
01 Oct 1976
TL;DR: K-Ar ages of a number of samples from Rajmahal and Deccan Traps and from basaltic dykes of Gondwanas have been measured as discussed by the authors.
Abstract: K-Ar ages of a number of samples from Rajmahal and Deccan Traps and from basaltic dykes of Gondwanas have been measured. The results suggest that the Early Rajmahals erupted in the middle of early Cretaceous (∼ 110 my) and probably continued to be active till the end of Cretaceous. Deccan activity started in Gujarat-Kathiawar area in Early Paleocene and spread over almost the entire area in next 5–7 my. However, in the north-eastern region of the traps around Chindwara and Amarkantak, the basalts were laid in the middle of the Eocene (∼ 47 my). The measured ages of Deccan dykes suggest a subdued hypabyssal activity continuing till the end of Eocene or beyond.
43 citations
TL;DR: A new response of cyclic AMP at the cellular level in the moss protonema is described; the results show that it is involved in the differentiation of chloronema cells.
Abstract: CYCLIC AMP evokes or mediates a multitude of responses in animals and microorganisms1,2 Whereas the occurrence and regulatory role of cyclic AMP in these organisms is well established, little is known about its role in plants Cyclic AMP has been reported to mimic certain effects of gibberellins, indoleacetic acid (IAA) and phytochrome in higher plants but in no case has its endogenous presence been unequivocally demonstrated3,4 We describe here a new response of cyclic AMP at the cellular level in the moss protonema; the results show that it is involved in the differentiation of chloronema cells The intracellular level of cyclic AMP in these cells is four- to sevenfold higher as compared with that in caulonema cells In a leaky chloronema-repressed mutant isolated by us, cyclic AMP is shown to enhance the differentiation of chloronema filaments
38 citations
TL;DR: Pyridine ring is affected differently by different substituents for the same substituent and the ring distortion depends upon the position of the substitusent as discussed by the authors. But this is not the case for all substitusents.
33 citations
TL;DR: In this article, it was shown that a primordial tachyon in the big-bang universe cannot survive unless it had very large energy initially, and this time barrier is found to exist even in the quantum-mechanical discussion of tachyons.
Abstract: The propagation of tachyons in an expanding universe is discussed. It is shown that a primordial tachyon in the big-bang universe cannot survive unless it had very large energy initially. In an indefinitely expanding universe, the tachyon trajectory turns back in time. This time barrier is found to exist even in the quantum-mechanical discussion of tachyons. This property is used to set limits on the mass of a tachyon. The possible astronomical checks on the hypothesis that neutrinos or photons may be tachyonic are also discussed.
30 citations
TL;DR: In this paper, the Mossbauer effect at dilute Fe3+ and Fe2+ impurities in LiNbO3 and LiTaO3 has been measured.
Abstract: The Mossbauer effect at dilute Fe3+ and Fe2+ impurities in LiNbO3 and LiTaO3 has been measured. Lattice site substitution and the charge compensating process are discussed.
26 citations
TL;DR: The most sensitive search for quasistable neutral particles with masses approximately-greater-than-2 GeV/c/sup 2 was carried out in this paper, where the particle masses were determined from their flight time and kinetic energy.
Abstract: We have carried out a search for neutral hadrons with masses approximately-greater-than2 GeV/c/sup 2/ and proper lifetimes approximately-greater-than10/sup -7/ sec in the M4 neutral beam at Fermilab. The particle masses were determined from their flight time and kinetic energy. Our upper limits for the production cross section of such particles are 10/sup -1/ to 10/sup -3/ times those for the production of psi's by protons for comparable kinematic conditions. This is the most sensitive search to date for quasistable neutral particles with masses approximately-greater-than2 GeV/c/sup 2/. (AIP)
24 citations
TL;DR: In this article, the global dimension of a polynomial algebra over a commutative field of characteristic 0.6 was shown to be the same as that of a finite-dimensional nilpotent Lie algebra over k.
Abstract: Let k be a commutative field of characteristic 0. Let g be a Lie algebra over k. Let / be a A> valued 2-cocycle on the \" standard complex\" for g. We set 9(/) = T(Q)/Uf(Q), where T(g) denotes the tensor algebra of the vector space g and Uf(o) the two-sided ideal of T(g) generated by all elements of the form x®y-y® x-[x,y]-f(x,y) for x,ye$. It is known [15] that g(/) is a filtered ^-algebra whose associated graded algebra is isomorphic to a polynomial algebra over k and that every filtered A>algebra with this property is isomorphic to one such. In this paper we determine (§2, Theorem 2.6) the global dimension of g(/), where g is a finite-dimensional nilpotent Lie algebra over k, and deduce some interesting corollaries. In §1 we prove some results which are used in the proof of the main theorem.
TL;DR: In this paper, color effects in unified gauge theories with lepton probes are discussed and quantitatively discussed at energies higher than 50 GeV, and several new results pertaining to these effects are derived.
Abstract: In unified gauge theories with color (excitable by lepton probes), color effects become manifest in the asymptotic region through gluon terms. Several new results pertaining to these are derived and quantitatively discussed. These may be testable at energies higher than 50 GeV now available.
TL;DR: In this paper, it is shown that a tachyon falling radially inwards never reaches the space-time singularity at the origin, instead, it is bounced back at a point inside the Schwarzschild radius.
Abstract: The motion of a tachyon in the empty Schwarzschild solution outside a massm is discussed. It is shown that a tachyon falling radially inwards never reaches the space-time singularity at the origin. Instead, it is bounced back at a point inside the Schwarzschild radius. The causal and non-causal aspects of such a bounce are considered. It is shown that a tachyon dropped from a radial co-ordinate 3.27m always arrives later than its starting time. The more general case of a tachyon with a finite angular momentum is also analyzed. The possible astrophysical consequences of the presence of tachyons near condensed or collapsing objects and black holes are qualitatively discussed.
TL;DR: Human milk samples from American, Hindu and Parsi donors are compared to determine the relative amounts of reverse transcriptase inhibitors present, and the presence of RNase is confirmed, and variations in the level ofRNase are observed in samples from different ethnic groups.
Abstract: WE have compared human milk samples from American, Hindu and Parsi donors with a view to determining the relative amounts of reverse transcriptase inhibitors1–5 present in them. Our intention was to find out whether samples from any specific ethnic group are advantageous for the study of type B virus-like particles in milk2,6–8 and for purification of virus-associated enzymes. We also hoped that when sufficient data become available, such studies would be interesting from an epidemiological point of view, to test whether the inhibitors provide protection from mammary cancer. We have confirmed the presence of RNase in milk samples, and have observed variations in the level of RNase in samples from different ethnic groups. Careful examination has also revealed the presence of a protein factor, associated with plasma membranes in milk samples, that stimulates RNA-directed DNA synthesis (RDDS) in vitro in oncornaviruses.
TL;DR: In this article, the authors extended the results of Mrowka, M. Rajagopalan and T. Soundararajan about compact dispersed spaces and solved several problems for such spaces raised by them.
Abstract: This investigation consolidates and extends known results concerning classes of spaces in which sequential compactness is equivalent to countable compactness. At the same time results of S. Mrowka, M. Rajagopalan and T. Soundararajan about compact dispersed spaces are extended. Several problems for such spaces raised by them are solved. A convecture of Tironi and Isler is dispress.
TL;DR: In this paper, the authors measured the total and differential cross sections of p p → n n in the 700 −760 MeV/c incident momentum region and found that σCE = 10.7 ± 0.2 mb at the average momentum of 730 MeV /c.
TL;DR: The genetic loci for two enzymes of glycolysis have been established by transductional crosses by identifying a locus affecting the structure of glyceraldehyde 3-P dehydrogenase and a structural determinant for glycerate3-P kinase.
Abstract: The genetic loci for two enzymes of glycolysis have been established by transductional crosses. The eno locus, likely to be the structural gene for enolase maps in the 52-minute region of the Escherichia coli chromosome. A structural determinant for glycerate 3-P kinase (pgk) is located near serA. The map order is speB-pgk-serA-lysA-argA-eno-cysC. In the 35-minute region maps a locus affecting the structure of glyceraldehyde 3-P dehydrogenase.
Journal Article•
TL;DR: In this article, the authors consider a homogeneous space M = G/⌈ where G is a Lie group and ⌈ is a lattice in G, and they define a discrete subgroup of G such that M admits a finite G-invariant Borel measure.
Abstract: Let M = G/⌈ be a homogeneous space where G is a Lie group and ⌈ is a lattice in G, i.e. a discrete subgroup of G such that G/⌈ admits a finite G-invariant Borel measure.
TL;DR: In this article, the microwave spectrum of 3-fluoropyridine has been observed in the frequency range of 8-18 GHz at dry ice temperature and the rotational constants, the centrifugal distortion constants, and the 14 N quadrupole coupling constants were obtained.
TL;DR: In this article, the second-order Doppler shift, recoil-free fraction (f), and hyperfine field (H) are studied for disordered Co49Fe51 and Ni48Fe52 alloys in the temperature range 4.2 to 1000 K.
Abstract: Variation of second-order Doppler (SOD) shift, recoil-free fraction (f), and hyperfine field (H) are studied for disordered Co49Fe51 and Ni48Fe52 alloys in the temperature range 4.2 to 1000 K. The SOD shift and f-factor are analysed in terms of the Debye approximation. The average reduced field for Ni48Fe52 is fitted to a modified Brillouin function. The average reduced field for Co49Fe51 alloy shows a kink around 823 K similar to magnetisation data.
Die Anderung der Dopplerverschiebung zweiter Ordnung (SOD), des ruckstosfreien Anteils (f) und des Hyperfeinfeldes (H) werden fur fehlgeordnete Co49Fe51 und Ni48Fe52- Legierungen im Temperaturbereich von 4,2 bis 1000 K untersucht. Die SOD-Verschiebung und die Werte des f-Faktors werden mit der Debye-Approximation analysiert. Das mittlere reduzierte Feld fur Ni48Fe52 wird an eine modifizierte Brillouin-Funktion angepast. Das mittlere reduzierte Feld fur Co49Fe51- Legierungen zeigt, ahnlich wie die Magnetisierungswerte, bei etwa 823 K einen Sprung.
TL;DR: In this paper, the a.c. conductivity of a -Ge and a -InSb film is found to obey a ω s law with 0.4 s s s and its value goes down as the temperature is lowered.
TL;DR: In this paper, the leading Regge trajectory on which the mesons lie satisfies the equation (a+b), where b is the number of mesons that lie in the plane of the trajectory.
Abstract: It is proposed that the leading Regge trajectory on which ${q}_{i}{\overline{q}}_{j}$ mesons ($i,j=u,d,s,c\dots{}$) lie satisfies the equation ${\ensuremath{\alpha}}_{\mathrm{ij}}(t)=a+\ensuremath{\alpha}_{\mathrm{ij}}^{}{}_{}{}^{\ensuremath{'}}(t\ensuremath{-}b)$ with ${(\ensuremath{\alpha}_{\mathrm{ij}}^{}{}_{}{}^{\ensuremath{'}})}^{2}=\ensuremath{\alpha}_{\mathrm{ii}}^{}{}_{}{}^{\ensuremath{'}}\ensuremath{\alpha}_{\mathrm{jj}}^{}{}_{}{}^{\ensuremath{'}}$. The latter is justified with use of the factorization property of Regge poles. $\frac{J}{\ensuremath{\psi}}$-like states associated with still heavier quarks are predicted to be not narrow if their mass exceeds 5.6 GeV.
TL;DR: The crystal structure of the title compound, [Fe(CS2NBu2)3],C6H6, has been determined at 295 K from diffractometer data and refined by least squares to a residual of 0.071 for 3077 'observed' reflections as mentioned in this paper.
Abstract: The crystal structure of the title compound, [Fe(CS2NBu2)3],C6H6, has been determined at 295 K from diffractometer data and refined by least squares to a residual of 0.071 for 3077 'observed' reflections. Crystals are orthorhombic, Pncn, a = 23.660(9), b = 17.331(7), c = 10.349(9) A. Unlike the unsolvated derivative, the present compound has a magnetic moment of 3.6 B.M. at 295 K. Its molecular symmetry is 2, (FeS) being 2.34, A. The role of the benzene solvent, at a lattice site, is not indicative of any strong intermolecular interaction.
TL;DR: In this paper, the significance of accelerator searches for the new particles discovered in the Kolar Gold Mine experiments depends on the characteristics of the models of these particles, and models that could give cosmic ray neutrinos a great advantage over accelerator Neutrinos are presented.
TL;DR: In this article, the effect of absorption by the intergalactic medium in general, and of the above type in particular, on the measurement of the deceleration parameter q 0 of the expanding universe is discussed.
Abstract: In a recent attempt to explain the cosmic microwave background without the big bang, a thermalization mechanism involving intergalactic whisker grains of graphite was proposed. The effect of absorption by the intergalactic medium in general, and of the above type in particular, on the measurement of the deceleration parameterq
0 of the expanding universe is discussed. Its effect is shown to be comparable in magnitude but opposite to that of the luminosity evolution in galaxies. A consequential selection effect is also discussed.
TL;DR: In this paper, a U3 gauge theory of weak and electromagnetic interactions is proposed, which makes use of six flavors of quarks (Charm, taste and grace plus the three old SU3 flavours), each in three colours, and correspondingly six lepton-types.
Abstract: Motivated by a desire to attempt a unified description of some recently observed phenomena such as the unusual events in the deep underground experiments at Kolar, the dilepton events initlated by high energy laboratory neutrino beams, the possible production of a new heavy lepton ine+e− annihilation along with the conventional weak interaction processes, a U3 gauge theory of weak and electromagnetic interactions is proposed. The theory makes use of six flavours of quarks (Charm, Taste and Grace plus the three old SU3 flavours), each in three colours, and correspondingly six lepton-types. The introduction of the corresponding fermions, and their assignment to representations of the proposed U3 group, is dictated by the stringent requirements of attaining an anomaly free renormalizable gauge theory and of ensuring that the neutral currents turn out strangeness-preserving. A spontaneous gauge symmetry breaking mechanism is employed to generate the mechanical masses of the vector gauge-bosons of the theory (other than the photon) and of the quarks and the leptons. Diagonalisation of the quark mass matrix so generated enables a natural introduction of mixing angles including the Cabibbo-angle.
TL;DR: In this article, the g-factor of the 659 keV, 3/2+ state was measured using time differential perturbed angular correlation technique in an external field of 20·2 kG.
Abstract: We have measured theg-factor of the 659 keV, 3/2+, state in117In, using time differential perturbed angular correlation technique. The spin precession of this state was measured in an external field of 20·2 kG. The values of the Larmor precession frequencyω and theg-factor are obtained to be (60·1±0·3)106 rads/sec and 0·625±0·007 respectively.
TL;DR: In this article, the properties of high-spin states in /sup 209/At have been studied with the /sup 206/Pb(/sup 6/Li, 3n..gamma..)/sup 209 /At reaction.
Abstract: The properties of high-spin states in /sup 209/At have been studied with the /sup 206/Pb(/sup 6/Li, 3n..gamma..)/sup 209/At reaction. In-beam measurements with Ge(Li) detectors of ..gamma..-ray excitation functions, ..gamma..-..gamma.. coincidences, ..gamma..-ray angular distributions, and pulsed beam-..gamma.. timing were made to establish decay schemes, level energies, spin-parity assignments, isometric lifetimes, and magnetic moments. High-spin states involving three valence protons in the 1h/sub 9/2/, 2f/sub 7/2/, or 1i/sub 13/2/ orbitals were identified. The electromagnetic properties observed in /sup 209/At were compared with those in the closed-neutron core nucleus /sup 211/At to examine the influence of the two neutron holes on the proton structure; microscopic calculations of this influence were carried out in perturbation theory. (AIP)