Showing papers by "Tata Institute of Fundamental Research published in 1969"
TL;DR: An epidemiologic house‐to‐house survey of oral cancer and lcukoplakia among 50,915 adult villagers in 4 states of India which were selected according to various types of chewing and smoking habits showed variations in the type of hyperkeratosis which may depend upon habits.
Abstract: Results of an epidemiologic house-to-house survey of oral cancer and leukoplakia among 50915 adult villagers in 4 states of India which were selected according to various types of chewing and smoking habits are presented. 26 oral cancer cases were found in the survey. There was a predominance of men. Leukoplakias were already observed in the 15-24 year old age group and a considerable number were in the 25-34-year age group. Intra-oral locations of the leukoplakias were found to vary within the 4 states depending on the chewing and smoking habits prevailing. The leukoplakias were analyzed with regard to intra-oral locations and correlation with habits. Special habits such as hookli smoking and reverse smoking were associated with leukoplakias on the labial mucosa and on the palate respectively. The histologic analysis of biopsies from 723 leukoplakias showed variations in the type of hyperkeratosis which may depend on habits. The prevalence of epithelial atypia ranged from 3-12.4% in the 4 states. Epithelial atypia was seen in 8.4% of homogeneous leukoplakias but in 59.1% of speckled leukoplakias.(BJB (AU. MOD.))
206 citations
TL;DR: New techniques considerably extend the usefulness of meteoritic minerals in the study of the composition of prehistoric cosmic radiation as mentioned in this paper, and they can be used in the analysis of meteorite meteorites.
Abstract: New techniques considerably extend the usefulness of meteoritic minerals in the study of the composition of prehistoric cosmic radiation.
133 citations
TL;DR: Fossil tracks in several silicate crystals present in the dark phases of gas-rich meteorites (Kapoeta and others) show that they were irradiated at low temperatures as individuals in a very low density atmosphere by corpuscular radiation of cosmic composition as mentioned in this paper.
Abstract: Fossil tracks in several silicate crystals present in the dark phases of gas-rich meteorites (Kapoeta and others) show that they were irradiated at low temperatures as individuals in a very low density atmosphere by corpuscular radiation of cosmic composition.
78 citations
01 Jan 1969
TL;DR: In this article, the concentrations of dissolved uranium and radium isotopes have been determined in the waters of several Indian rivers, and the concentration of uranium (U-238) is found to vary between 0·01 −7·0 micrograms/litre, depending primarily on the terrain through which the river flows.
Abstract: The concentrations of dissolved uranium and radium isotopes have been determined in the waters of several Indian rivers. The concentration of uranium (U-238) is found to vary between 0·01–7·0 micrograms/litre, depending primarily on the terrain through which the river flows. From the available data on the activity ratios, U-234/U-238, concentration of U-238 in rivers and the amount of uranium depositing on the ocean floor, a material balance calculation has been attempted. This shows that the supply of uranium to sea by rivers based on above measurements, is inadequate to explain the observed concentrations of U-238 and U-234 in the oceans.
48 citations
TL;DR: In this paper, the effects of geological annealing of fission tracks in muscovite are compared with those produced in the laboratory at high temperatures, and their influence on dating by fission track method examined.
48 citations
TL;DR: In this article, lower bounds on the ratio of the rate of a two-photon intermediate state with the absorptive part of the amplitudes were obtained. But the lower bound was only for the amplitude amplitudes.
Abstract: Using a model in which the decays ${K}_{S,L}\ensuremath{\rightarrow}l\overline{l}$ occur through a two-photon intermediate state, and considering only the absorptive part of the amplitudes, we obtain lower bounds on the ratios $\frac{\mathrm{Rate}({K}_{S,L}\ensuremath{\rightarrow}l\overline{l})}{\mathrm{Rate}({K}_{S,L}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})}$.
46 citations
01 Jan 1969
TL;DR: In this article, the authors measured several radionuclides lighter than Ni, with half-life ≥ 2 weeks and rare gas isotopes of He, Ne, Ar, Kr (including 2 × 105 year 81Kr), and Xe have been measured in two samples from the amphoterite Saint-Severin.
Abstract: Several radionuclides lighter than Ni, with half-life ≥ 2 weeks and rare gas isotopes of He, Ne, Ar, Kr (including 2 × 105 year 81Kr), and Xe have been measured in two samples from the amphoterite Saint-Severin. The concentration of low-energy products 26Al, 22Na, 21Ne, 53,54Mn, and 83Kr are lower than are normally encountered in stone meteorites of this size, whereas the high-energy products 10Be and 38Ar (in the troilite phase) occur in normal concentrations, suggesting that the samples analyzed (from stone D) were situated in a region where the secondary cosmic radiation is only slightly developed. A comparison with calculated production rates indicates that the samples were, on the average, located at about 3–4 cm from the preatmospheric surface of the meteorite. This conclusion is further supported by high 22Ne/21Ne and 78Kr/83Kr ratios as well as the high track density of heavy cosmic radiation (Z> 24) in hypersthene grains from these samples, and the small calculated neutron density. The cosmic-ray exposure age of this meteorite as calculated from the various pairs of nuclides is (11.2 ± 1.0) × 106 years. It is shown that the relative spallation mass yields of Kr depend on the energy spectrum of cosmic rays.
40 citations
TL;DR: In this article, the foundations of geometry are investigated in the context of geometry foundations, and the authors propose a framework for their work, which is based on CMA-ARTICLE-1969-001.
Abstract: Keywords: foundations of geometry Reference CMA-ARTICLE-1969-001doi:10.1007/BF02564531 Record created on 2008-12-16, modified on 2016-08-08
38 citations
34 citations
01 Jan 1969
TL;DR: In this article, the depth variation of fossil-track densities in the hypersthene and oligoclase crystals sampled from several cores taken from the least ablated regions of the meteorite Saint-Severin was investigated.
Abstract: We present here experimental data on the depth variation of fossil-track densities in the hypersthene and oligoclase crystals sampled from several cores taken from the least ablated regions of the meteorite Saint-Severin. The implications of these results (and of those in the Patwar meteorite) to the extent of atmospheric/preatmospheric ablation, and to the time-averaged flux and energy spectrum of cosmic-ray iron-group nuclei during the last 10–50 × 106 years, are discussed.
28 citations
TL;DR: No malignant transformation of leukoplakia lesion was reported after a 5-year follow-up study, and no lesions diagnosed as clinical leukplakia were found to be carcinoma in situ.
TL;DR: In this article, it was shown that nuclear interaction of these particles would also produce fluxes of secondary neutrons and gamma rays detectable at the earth, and a comparison of the expected intensities of these secondaries with the present upper limit intensities during solar flares was made.
Abstract: It has previously been suggested that the energy for the optical emission of solar flares was provided by ionization losses of accelerated particles in the flares. We show that nuclear interaction of these particles would also produce fluxes of secondary neutrons and gamma rays detectable at the earth. A comparison of the expected intensities of these secondaries with the present upper limit intensities during solar flares shows that such an origin from the optical emission energy is consistent with the measured limits.
TL;DR: A stochastic model based on tape theory of mRNA function is developed and theoretical consequences of the model such as decay of mRNA and its relationship with protein synthesis, size-distribution of polyribosomes, sedimentation profile of rapidly labelled RNA, association of nascent protein with poly ribosomes and bacterial enzyme induction are discussed.
TL;DR: The intensity of the new microwave radiation observed by Shivanandan, Houck, and Harwit as discussed by the authors was sufficient to produce, by Compton scattering on cosmic-ray electrons, the flux and distribution of \ensuremath{\sim}100-MeV $\ENSuremath{gamma}$ rays reported by Clark, Garmire, and Kraushaar.
Abstract: The intensity of the new microwave radiation observed by Shivanandan, Houck, and Harwit is adequate to produce, by Compton scattering on cosmic-ray electrons, the flux and distribution of \ensuremath{\sim}100-MeV $\ensuremath{\gamma}$ rays reported by Clark, Garmire, and Kraushaar.
TL;DR: In this article, a free volume model was developed to describe the experimentally observed I 2 − τ 2 correlation in molecular materials and phase changes were interpreted in terms of this model.
TL;DR: It is shown that [unk], the fundamental domain omega for an arbitrary lattice in a real rank one, real simple Lie group, is finitely presentable and is almost always rigid.
Abstract: We construct a fundamental domain ω for an arbitrary lattice [unk] in a real rank one, real simple Lie group, where ω has finitely many cusps (i.e., is a finite union of Siegel sets) and has the Siegel property (i.e., the set {γ [unk] [unk]|ωγ [unk] ω [unk] ϕ} is finite). From the existence of ω we derive a number of consequences. In particular, we show that [unk] is finitely presentable and is almost always rigid.
TL;DR: In this paper, the spin relaxation effects in the antiferromagnetically ordered system in a wide temperature range (100 to 289 °K) below the Neel temperature was found to be almost linear from 10 °K onward.
Abstract: The study of Mossbauer spectra of the solid solution 0.905 Cr2O3—0.035 Fe2O3 at different temperatures in the range 10 to 293 °K has revealed spin relaxation effects in this antiferromagnetically ordered system in a wide temperature range (100 to 289 °K) below the Neel temperature (289 °K). The variation of the hyperfine field with temperature is found to be almost linear from 10 °K onward. Above 100 °K the hyperfine field calculated from the total splitting is more than that obtained from ground state splitting. The observed results are compared with the existing spin-flip theory based on a stochastic model.
TL;DR: In this paper, the authors report the observation of sudden changes in the intensity of Sco X-1 by a factor of about 3 recorded in the energy interval 29.9 −52.3 keV on December 22, 1968 between 04 h 27 m and 05 h 53 m UT.
Abstract: In this note we wish to report briefly the observation of sudden changes in the intensity of Sco X-1 by a factor of about 3 recorded in the energy interval 29.9–52.3 keV on December 22, 1968 between 04 h 27 m and 05 h 53 m UT. The observation was made with an X-ray telescope flown in a balloon from Hyderabad, India. The balloon was launched at 0200 hr UT and reached the ceiling of 7.5 g/cm2 of residual atmosphere at 0435 hr UT. The X-ray telescope consisted of a NaI (T1) crystal with an area of 97.3 cm2 and thickness 4 mm, surrounded by both active and passive collimators. The telescope was mounted on an oriented platform which was programmed to look in four specified directions successively, of azimuths, o = 0°, 110°, 180° and 310° (o=0° being North and o=90°, West), spending about 4 min in each direction during a cycle of period of about 16 min The axis of the telescope was inclined at an angle of 32° with respect to the zenith. A pair of crossed flux gate magnetometers provided information every 8.2 sec on the azimuth of the telescope. The pulse heights from the X-ray detector were sorted into several channels extending from 10 to 120 keV. An Am241 source came into the field of view of the telescope once in 15 min for about 30 sec to provide in-flight calibration of the detector. The meridian transit of Sco X-1 was at 0454 hr UT. Just before the balloon reached the ceiling Sco X-1 was in the field of view of the telescope for 3 min and 41 sec. After the balloon reached ceiling, Sco X-1 was in the field of view of the telescope on five occasions between 0443 and 0553 hr UT. During the last observation, however, the balloon had lost altitude by about 1 g/cm2.
TL;DR: Pais and Treiman as discussed by the authors studied the implications of the possibility of real intermediate states in the decay of this decay and showed how their results are modified when account is taken of the real intermediate state in this decay.
Abstract: Pais and Treiman have studied the implications of $\mathrm{CP}$ and $\mathrm{CPT}$ invariance for the decay ${K}_{L}\ensuremath{\rightarrow}l\overline{l}$ We indicate how their results are modified when account is taken of the possibility of real intermediate states in this decay
TL;DR: In this article, the effect of wavelength dependent polarizabilities on Rayleigh scattering cross-sections has been investigated and the importance of Rayleigh scatterometry vis-a-vis pure absorption has been discussed.
Abstract: The Rayleigh scattering cross-sections of He, C, N and 0 have been computed by quantum defect method. Fairly good agreement has been obtained between the results of dipole length and dipole velocity formalisms. The wavelength independent part of the polarizabilities obtained in the calculation have been compared with the static polarizabilities given by others. At large wavelengths, the Rayleigh scattering cross-sections of He, C, N and 0 relative to H, have been found to be approximately in the ratio of 0.1 : 7.9 : 4.I : 1.4. The effect of wavelength dependent polarizabilities on Rayleigh scattering cross-sections has also been investigated. The importance of Rayleigh scattering vis-a-vis pure absorption has been discussed.
TL;DR: In this paper, the parameters of Bethe's density-dependent effective interaction suggested by Bethe are determined from restricted Hartree-Fock calculations in 4 He, 16 O, 40 Ca and infinite nuclear matter.
01 Jan 1969
TL;DR: In this article, radio-chemical analysis of near-surface materials from the amphoterite Saint-Severin was carried out in two successive stages: regions of least ablation are pin-pointed by measurements of the density of cosmic-ray fossil tracks made visible by chemical etching of hypersthene and oligoclase crystals; results of nondestructive analyses for total Al26 + Na22, as well as for Al26 and Na22 separately in two samples are presented.
Abstract: The work presented here provides, for the first time, conclusive evidence for the presence of an appreciable flux of low-energy particles (10
TL;DR: In this article, an upper bound of 1.2 × 10-2 neutrons cm-2 sec-1 was obtained for a flare of importance 2B for neutrons of energy 15-150 MeV.
Abstract: On the basis of solar flare forecasts, balloon flights were made from Hyderabad, India (vertical geomagnetic threshold rigidity of 16.9 GV), to detect the possible emission of high energy neutrons during solar flares. The detector comprised of a central plastic scintillator, completely surrounded by an anticoincidence plastic scintillator shield. The instrument responds to neutrons of about 15–150 MeV and gamma rays of about 5–30 MeV with about the same efficiency. The detector was flown to an atmospheric depth of 25 g cm-2 on February 26, 1969; while the balloon was at ceiling a flare of importance 2B and one of 1N occurred. No perceptible flare associated increase in the counting rate was observed. Using the observed counting rates, an upper limit of 1.2 × 10-2 neutrons cm-2 sec-1 is obtained for the first time for a flare of importance 2B for neutrons of energy 15–150 MeV. The corresponding upper limit for gamma rays of energy 5–30 MeV is found to be ∼ 10-2 photons cm-2 sec-1. The neutron flux limits are compared with the recent calculations of Lingenfelter.
TL;DR: In this article, the shape of the spectrum of cosmic ray electrons in the 100 GeV range and beyond can provide information about a variety of problems in cosmic ray astrophysics, and an investigation was designed to determine the electron spectrum beyond 200 GeV.
Abstract: THE shape of the spectrum of cosmic ray electrons in the 100 GeV range and beyond can provide information about a variety of problems in cosmic ray astrophysics. The differential energy spectrum between a few GeV and about 100–200 GeV can be reliably represented1 by a single power law with an index of −2.62. We now describe an investigation designed to determine the electron spectrum beyond 200 GeV.
01 Jan 1969
TL;DR: In this article, a correlation was observed between the lifetime and two-photon annihilation intensity by pick-off process of ortho-positronium in molecular materials, and an empirical model, in terms of free volume, was developed to explain this correlation.
Abstract: A correlation is observed between the lifetime and two-photon annihilation intensity by pick-off process of ortho-positronium in molecular materials. An empirical model, in terms of free volume, is developed to explain this correlation. The variation in lifetime and intensity with change of temperature and pressure, and due to melting of crystals, and glass-transition in polymers is considered, on the basis of this model.
TL;DR: Radon concentrations have been measured in the surface air over the Indian Ocean and the Arabian Sea as discussed by the authors, indicating a gradual mixing between the lower maritime air and the continental air aloft, indicating a significant contribution of moisture to the monsoon current by evaporation over the east Arabian Sea.
TL;DR: In this article, a simple procedure was described for the preparation of carrier-free copper-64,67 nuclides from a zinc target exposed to fast neutrons, where the irradiated target was dissolved in water, and the pH of the solution was adjusted to about six.
Abstract: A simple procedure is described for the preparation of carrier-free copper-64,67 nuclides from a zinc target exposed to fast neutrons. The irradiated target is dissolved in water, and thepH of the solution is adjusted to about six. Radioactive copper nuclides are then extracted with a 1% solution of resacetophenone oxime in cyclohexanone. Zinc is not extracted under these conditions. Radiocopper is back-extracted by shaking the organic phase with dilute mineral acid. About 5 mCi of carrier-free64Cu can be obtained from 1 g of zinc.
TL;DR: In this article, a fully antisymmetrized cluster-model wave function for 6Li is used for calculating the matrix element of the reaction6Li(p, pd)4He.
Abstract: A fully antisymmetrized cluster-model wave function for6Li is used for calculating the matrix element of the reaction6Li(p, pd)4He. The calculations are carried out in plane-wave impulse approximation and the effect of the various terms arising from antisymmetrization is discussed.
TL;DR: In this article, the g-factor of the 321 keV 9 2 − state of 125Te has been measured to be g = −0.58±0.24 from the rotation ωτ of the angular correlation pattern of the 204.3−176.7 keV gamma ray cascade in externally applied fields.