Showing papers by "Tata Institute of Fundamental Research published in 1990"
TL;DR: The critical state is characterized, and its entropy for an arbitrary finite lattice in any dimension is determined, and the two-point correlation function is shown to satisfy a linear equation.
Abstract: We study a general Bak-Tang-Wiesenfeld--type automaton model of self-organized criticality in which the toppling conditions depend on local height, but not on its gradient. We characterize the critical state, and determine its entropy for an arbitrary finite lattice in any dimension. The two-point correlation function is shown to satisfy a linear equation. The spectrum of relaxation times describing the approach to the critical state is also determined exactly.
856 citations
TL;DR: The statistical description of a system containing a large number of particles which interact via Newtonian gravity is discussed in this paper, which exhibits several peculiarities due to the long range, unshielded nature of the gravitational interaction.
559 citations
01 Apr 1990-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The L3 experiment as discussed by the authors is one of the six large detectors designed for the new generation of electron-positron accelerators, which is the only detector that concentrates its efforts on limited goals of measuring electrons, muons and photons.
Abstract: The L3 experiment is one of the six large detectors designed for the new generation of electron-positron accelerators. It is the only detector that concentrates its efforts on limited goals of measuring electrons, muons and photons. By not attempting to identify hadrons, L3 has been able to provide an order of magnitude better resolution for electrons, muons and photons. Vertices and hadron jets are also studied. The construction of L3 has involved much state of the art technology in new principles of vertex detection and in new crystals for large scale electromagnetic shower detection and ultraprecise muon detection. This paper presents a summary of the construction of L3.
505 citations
TL;DR: In this paper, a field theoretic formulation for one-dimensional string theory is given by the collective field representation of the matrix model and leads to a physical interpretation of the theory as that of a massless scalar field in two dimensions.
Abstract: We describe a field theoretic formulation for one-dimensional string theory. It is given by the collective field representation of the matrix model and leads to a physical interpretation of the theory as that of a massless scalar field in two dimensions. The additional dimension, coming from the large-N color of the matrix model, has an extent which goes to infinity in the continuum limit. The interactions of the field theory are non-zero only at the boundaries of this additional dimension.
339 citations
TL;DR: Areca nut is confirmed as the most important etiologic factor in oral submucous fibrosis and the relative risks increased with increase in the frequency as well as the duration of chewing habits.
Abstract: A case-control study to elucidate the etiology of oral submucous fibrosis was conducted in Bhavnagar, Gujarat. Sixty consecutively arriving oral submucous fibrosis patients at a dental clinic were selected as cases. An equal number of controls matched for age, sex, religion and socioeconomic status were selected from individuals who did not exhibit any oral mucosal lesion or condition. Among cases, 98% chewed areca nut regularly in one form or the other whereas among controls 35% chewed areca nut, giving an overall relative risk of 109.6. Areca nut chewing was practiced most commonly in the form of mawa: a mixture containing mainly areca nut (over 90% by weight), some tobacco, and a few drops of lime. Mawa chewers and those who chewed mawa along with other chewing habits showed very high relative risks. The relative risks increased with increase in the frequency as well as the duration of chewing habits. In a bivariate analysis the effect of frequency and duration of chewing appeared to be multiplicative. The present findings confirm areca nut as the most important etiologic factor in oral submucous fibrosis.
232 citations
TL;DR: Many of the results of this paper are new in the finite case (i.e., G is a finite-dimensional semisimple group over C) as well.
Abstract: Let G be a Kac-Moody group with Borel subgroup B and compact maximal torus T. Analogous to Kostant and Kumar [Kostant, B. & Kumar, S. (1986) Proc. Nati. Acad. Sci. USA 83, 1543-1545], we define a certain ring Y, purely in terms of the Weyl group W (associated to G) and its action on T. By dualizing Y we get another ring 1, which, we prove, is "canonically" isomorphic with the T-equivariant Ktheory KT(G/B) of GIB. Now KT(G/B), apart from being an algebra over KT(pt.) A(T), also has a Weyl group action and, moreover, KT(G/B) admits certain operators {DW},,w similar to the Demazure operators defined on A(T). We prove that these structures on KT(G/B) come naturally from the ring Y. By "evaluating" the A(T)-module W at 1, we recover K(G/B) together with the above-mentioned structures. We believe that many of the results of this paper are new in the finite case (i.e., G is a finite-dimensional semisimple group over C)
207 citations
TL;DR: In this paper, a nonperturbative formulation of 2D quantum gravity in terms of the large-N limit of matrix models is studied to include the effects of higher order curvature terms.
Abstract: The non-perturbative formulation of 2-dimensional quantum gravity in terms of the large-N limit of matrix models is studied to include the effects of higher order curvature terms. This leads to matrix models whose potential contains a symmetry breaking term of the form Tr ϕAϕA, where A is a given fixed matrix. This is studied in d = 0 dimensions and effectively induces additional terms of the form (Tr ϕk)2 in the one matrix potential. An exact solution to leading order of the potential V(ϕ) = 1/2 Tr ϕ2 + g/N Tr ϕ4 + g′/N2 (Tr ϕ2)2 is presented leading to 3 phases: γ = −1/2 (smooth surfaces), γ = 1/2 (branched polymer) and γ = 1/3 (intermediate phase). Including a Tr ϕ6 term in the potential gives rise to an additional phase with γ = 1/4. It is conjectured that for the general polynomial potential there are phases with γ = 1/n, n = 2, 3, …. The γ > 0 phases may correspond to c > 1 matter coupled to 2-dimensional gravity.
113 citations
TL;DR: Six X-linked loci which specify olfaction in Drosophila melanogaster are identified using a behavioral genetic approach and two groups of olfC alleles fall into two phenotypic classes according to their responses to different acetate esters.
Abstract: We have used a behavioral genetic approach to identify six V-linked loci which specify olfaction in Drosophila melanogasier. Mutations in five of these genes lead to partial anosmias affecting responses either to aldehydes (olfA, olfB, olfE and olfF) or to acetate esters (olfC). Only one of the mutants obtained in our screening (olfD) resulted in a insensitivity to several different odorants. olfA, olfE and olfC map close together in a small region of the chromosome between 7C and 7D. The alleles at the olfC locus fall into two phenotypic classes according to their responses to different acetate esters. The two groups of olfC alleles interact in-trans.
107 citations
TL;DR: In this article, it was shown that the string field theories formulated around these two different conformal field theories are actually the same theory, and that these two conformal fields may be regarded as different classical solutions of this string field theory.
105 citations
84 citations
TL;DR: In this article, it is shown that the goal of space valorization cannot be considered without relational investment between the partners and their accumulated background, and that the capacity of the territory to solve these problems will depend closely on the richness of the network and co-operations which it shelters or it will suggest.
TL;DR: In this article, a search for the neutral Higgs boson using the processes Z 0 → H 0 e + e −, Z0 → H ε + ε, Z ε → H τ + τ −, Zε → ε v v, and Z 0→ H 0 q q q, is performed on data collected by the ALEPH detector corresponding to about 11 550 events of Z0→ hadrons.
TL;DR: In this paper, a precise measurement of the cross section for e+e−→Z0→hadrons with the L3 detector at LEP was made, covering the s range from 88.28 to 95.04 GeV.
TL;DR: Although the decrease in the incidence in the intervention cohort was not statistically significant, the results underscored the causal role of areca nut chewing and indicated the potential for primary prevention of oral submucous fibrosis.
Abstract: Incidence of oral submucous fibrosis was calculated from a 10-yr prospective intervention study of 12,212 individuals with a strong component of health education on tobacco and area nut chewing Based on 11 new cases among 6341 chewers, the annual incidence was 80 per 100,000 among men and 290 for women An earlier 10-yr follow-up study, with no intervention component, served as control Based on 11 new cases among 3,809 chewers, the annual incidence was 213 per 100,000 for men and 457 for women controls Although the decrease in the incidence in the intervention cohort was not statistically significant due to small number of cases, the results underscored the causal role of areca nut chewing and indicated the potential for primary prevention of oral submucous fibrosis
TL;DR: In this paper, the expected flux of ultra-high-energy (> 10{sup 18}eV) protons in the present epoch due to a process which involves collapse or multiple self-intersections of a special class of closed cosmic string loops in the universe is estimated.
TL;DR: In this paper, it was shown that in the limit when the background ψcl is weak, QB can be identified with the BRST charge of a new conformal field theory (CFT) which is obtained by perturbing the orginal conformal fields theory (CTF) by a marginal operator.
TL;DR: In this article, the authors measured the properties of Z0 → b b decays using a sample of 944 inclusive muon events, corresponding to 18 000 hadron events obtained with the L3 detector at LEP.
03 Apr 1990
TL;DR: The use of an acoustic subword unit (ASWU)-based speech recognition system for the recognition of isolated words is discussed and it is shown that the use of a modified k-means algorithm on the likelihoods derived through the Viterbi algorithm provides the best deterministic-type of word lexicon.
Abstract: The use of an acoustic subword unit (ASWU)-based speech recognition system for the recognition of isolated words is discussed. Some methods are proposed for generating the deterministic and the statistical types of word lexicon. It is shown that the use of a modified k-means algorithm on the likelihoods derived through the Viterbi algorithm provides the best deterministic-type of word lexicon. However, the ASWU-based speech recognizer leads to better performance with the statistical type of word lexicon than with the deterministic type. Improving the design of the word lexicon makes it possible to narrow the gap in the recognition performances of the whole word unit (WWU)-based and the ASWU-based speech recognizers considerably. Further improvements are expected by designing the word lexicon better. >
TL;DR: The relationship between the Kac-Moody and Virasoro central charges was studied in this article for rational conformal field theories, showing that the residues of the characters at the pole in z correspond to the central charges for the c < 1 minimal models.
TL;DR: In this paper, the finite temperature transition in QCD with four flavors of dynamical quarks was studied on an 8×16 3 lattice for quarks of mass ma = 0.01.
TL;DR: In this article, the authors present the results from a search for the light neutral scalar Higgs boson h° and the pseudoscalar higgs Boson A° of the minimal super-symmetric standard model.
TL;DR: In this paper, a table is presented showing all close pairs of QSOs and galaxies that were found in a computer-aided search of catalogs of the QSO and bright galaxies and an extensive search of the literature.
Abstract: A table is presented here listing all close pairs of QSOs and galaxies that were found in a computer-aided search of catalogs of QSOs and bright galaxies and an extensive search of the literature. There is a large excess of pairs with separations of 2 arcmin or less, or about 60 kpc, over the numbers expected if the configurations were accidental. The angular separation for 392 pairs adds to the evidence for physical association, and it is shown that selection effects are not important. A general rule is stated that QSOs tend to lie in the vicinity of normal galaxies much more often than is expected by chance whether or not the galaxies and the QSOs have the same redshifts. It is emphasized that this rule cannot be explained in terms of gravitational microlensing, and it is concluded that some part of the redshift of all classes of active nuclei is not associated with the expansion of the universe. 120 refs.
TL;DR: In this paper, the authors studied the existence and location theorems for the eigenvalues of a mathematical model of a tube bundle immersed in an inviscid compressible fluid and proved that the original eigenvalue problem is equivalent to that of determining the characteristic values of a linear, compact, selfadjoint operator.
Abstract: In this paper, we study some existence and location theorems for the eigenvalues of a mathematical model that describes the eigenfrequencies and eigenmotions of a tube bundle immersed in an inviscid compressible fluid. The model is a non-standard eigenvalue problem because it involves a non-local boundary condition, and the eigenvalues of the problem appear in two places: namely, in the equations and in this non-local boundary condition. The problem is treated by using methods from functional analysis. First, the existence of eigenvalues is stated by proving that the original eigenvalue problem is equivalent to that of determining the characteristic values of a linear, compact, selfadjoint operator. Next, the location theorems are established by obtaining explicit bounds for the eigenvalues. While some of these bounds are derived by applying general location theorems of the theory of compact selfadjoint operators, others are deduced by homotopy and continuity arguments.
TL;DR: In this article, it was shown that in the case of a monomial curve defined by a sequence of positive integers somee−1 of which form an arithmetic sequence, μO ≤ 2e − 3 and μ(P)≤e(e − 1)/2.
Abstract: LetO be a curve in the affine algebroide-space over a fieldK of characteristic zero. LetD be the module ofK-derivations andP the relation ideal ofO. Generators forD andP are computed in several cases. It is shown in particular that in the case of a monomial curve defined by a sequence ofe positive integers somee−1 of which form an arithmetic sequence, μO ≤ 2e - 3 and μ(P)≤e(e−1)/2.
TL;DR: In this paper, consistent quantization determines the renormalization of couplings in a quantum field theory coupled to gravity in two dimensions, where the dynamical degree of freedom of the two-dimensional metric plays the role of time in target space.
Abstract: We show how consistent quantization determines the renormalization of couplings in a quantum field theory coupled to gravity in two dimensions. The special status of couplings corresponding to conformally invariant matter is discussed. In string theory, where the dynamical degree of freedom of the two-dimensional metric plays the role of time in target space, these renormalization group equations are themselves the classical equations of motion. Time independent solutions, like classical vacuua, correspond to the situation in which matter is conformally invariant. Time dependent solutions, like tunnelling configurations between vacuua, correspond to special trajectories in theory space. We discuss an example of such a trajectory in the space containing the c < 1 minimal models. We also discuss the connection between this work and the recent attempts to construct non-perturbative string theories based on matrix models.
01 Dec 1990
TL;DR: In this paper, the existence and non existence of positive solution for the critical Sobolev exponent problem was studied and it was shown that Ω is a bounded domain in ℝn(n ≥ 4).
Abstract: In this paper we study the existence and non existence of positive solution for the critical Sobolev exponent problem − Δu =u(n + 2)/(n − 2) +λα(x)u) in Ω\(\frac{{\partial u}}{{\partial v}} = 0 on \partial B\), where Ω is a bounded domain in ℝn(n ≥ 4).
TL;DR: In this article, a homomorphism h: ker(Cores:, Br(S) +,Br(R)) + Pic(RjCores Pit(S), whose kernel consists precisely of classes of Azumaya S-algebras which support commuting involutions of both kinds was constructed.
01 Apr 1990
TL;DR: In this article, the expected flux of ultra-high-energy (> 10{sup 18}eV) protons in the present epoch due to a process which involves collapse or multiple self-intersections of a special class of closed cosmic string loops in the universe is estimated.
Abstract: We estimate the expected flux of ultrahigh-energy (> 10{sup 18}eV) protons in the present epoch due to a process which involves collapse or multiple self-intersections of a special class of closed cosmic string loops in the universe. We compare this flux with the observed flux of ultrahigh-energy cosmic rays, and discuss the implications. 19 refs., 1 fig.
TL;DR: In this paper, the authors measured the partial widths of the Z 0 into lepton pairs, and the forward-backward charge asymmetry for the process e + e − → μ + μ − using the L3 detector at LEP.