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This study was aimed at determination of the beryllium concentration and its temporal variation in stream water and sediment (mud). The metal ion distribution in the stream of length 3.2 km, near the beryllium facility was evaluated. Beryllium in stream water and sediment was estimated by Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS). The beryllium concentration in water and sediment, varied in the range of 0.01–0.2 ng/ml and 600–30,000 ng/g respectively. The distribution coefficient (Kd) calculated for each locations was observed to be in the range of 500–212,500. The variation of the beryllium concentration at sampling locations of stream, selected for the study, with respect to distance may be due to sorption capacity of the matrix and other reactions of the metal ion involved in water and sediments.

The Gamma-ray Burst Monitor consists of 12 sodium iodide and 2 bismuth germanate scintillation detectors designed to enhance the scientific returns from Fermi in the study of γ-ray bursts. It has a fixed non-paralyzing dead time of 2.604 μs for each detected event except for those in the overflow channel of the 12 bit analog to digital converter of each detector, which have a longer dead time of 10.42 μs. At very high counting rates the pulse pile-up effect in the detectors leads to spectral distortions and also to additional event losses. These effects are relevant for the spectral analysis of high-flux astrophysical events such as gamma-ray bursts, soft gamma repeaters and solar flares, as well as terrestrial gamma-ray flashes. In this paper we present the results of post-launch tests using engineering detectors and equipment on the ground, along with detailed simulations of these effects at very high counting rates. The simulations enable us to assess the qualitative and quantitative changes in spectral shapes and event losses at different count rates. The observed spectra at various count rates using high intensity radioactive sources such as Cs137 and Co60 agree well with the simulated spectra. We also re-test the analytical model developed previously to correct for the pulse pile-up effects in GBM detectors. We also study the expected spectral distortions of specific spectral models commonly used in GRB analysis, including the Band model and power-law models with and without a high-energy cutoff.

In the atmospheric Cerenkov technique gamma rays are detected against the abundant background produced by hadronic showers. In order to improve the signal to noise ratio of the experiment, it is necessary to reject a significant fraction of hadronic showers. Traditional background rejection methods based on image shape parameters have been extensively used for the data from imaging telescopes. However, non-imaging Cerenkov telescopes have to develop very different means of statistically identifying and removing cosmic ray events. Some of the parameters which could be potentially important for non-imaging arrays are the temporal and spectral differences, the lateral distributions and density fluctuations of Cerenkov photons generated by gamma ray and hadron primaries. Here we study the differences in fluctuations of Cerenkov photon density in the light pool at the observation level from showers initiated by photons and those initiated by protons or heavier nuclei. The database of simulated events for the PACT array has been used to evaluate the efficiency of the new technique. Various types of density fluctuations like the short range and medium range fluctuations as well as flatness parameter are studied. The estimated quality factors reflect the efficiencies with which the hadrons can be rejected from the data. Since some of these parameters are independent, the cuts may be applied in tandem and we demonstrate that the proton rejection efficiency of about 90% can be achieved. Use of density fluctuations is particularly suited for wavefront sampling observations and it seems to be a good technique to improve the signal to noise ratio.

The study was specifically aimed to obtain concentration of beryllium in various environmental matrices such as air, water and soil in the vicinity of the Beryllium Metal Plant situated at Turbhe, New Bombay. Two analytical techniques – Morin fluorescence method and Atomic Absorption Spectrophotometry using graphite furnace were standardised for beryllium estimation. The beryllium concentration in the natural matrices studied – air, water and soil were in the range of 0.41–0.43 ng m-3, 0.01–0.02 ng mL-1 and 325–767 ng g-1 respectively.

In view of the toxic nature of Beryllium and its compounds the disposal of waste materials containing beryllium needs prior evaluation. The present study was undertaken to obtain information on the leachability and immobilisation of beryllium from solid waste red-mud generated in processing Beryl at the Beryllium Metal Plant at Vashi, New Bombay. The studies showed that 62% of the total beryllium in red-mud can be extracted by water by repeated leaching over a period of 445 d. The mixing of the waste material with cement and casting into cement blocks reduced the leachability of beryllium to 0.11% which got further reduced to 0.02% by thermal curing of cement blocks.

We present the results from CCD photometry in the V, R and I bands, of the 'Dipper Asterism' region of the open cluster M67 based on observations carried out at the prime focus of the 2.3 m Vainu Bappu Telescope of the Vainu Bappu Observatory, Kavalur. The CCD parameters like the system gain and the readout noise are measured using several flatfield frames taken through the standard I filter. The CCD chip is calibrated using the photometric standards in the field and linear colour transformation relations are derived. Also a few new VRI photometric measurements are reported for the members of the cluster.

Mitochondrial DNA (mtDNA) from two breeds of cattle, viz., [Hariana (Bos indicus), Holstein (Bos taurus)] and Indian water buffalo (Bubalis bubalus), was analyzed using 13 restriction endonucleases which recognized an average of about 40 six-base sites. Polymorphism among cattle was detected with six of these enzymes. The two Holstein differed at six sites, whereas the Hariana breed (Bos indicus) did not show any site polymorphism. Surprisingly, the Hariana type differed by only one site from one of the Holstein types. The total size of buffalo mtDNA was estimated to be 16.4 kb. Polymorphism within the Murrah buffalo breed was observed with respect to a Bg/I site. Scarcely any of the restriction fragments of buffalo mtDNA matched those of cattle mtDNA.

GAMMA-RAY bursts (GRBs) vary in duration from hundreds of seconds down to several milliseconds. Early studies1 suggested that bursts with durations of

Cygnus X-3, an X-ray binary with an orbital period 4.8 hr was seen to be emitting γ-rays with the same period at TeV energies by several groups. In addition the Durham group (Chadwicket al. 1985) published their observations on the existence of a pulsar in the Cyg X-3 system, emitting TeV γ-rays with a periodicity of approximately 12.6 ms. We observed this object during 1986 October-November and did not detect any pulsed emission of TeV γ-rays in the range of periods from 12.5850 to 12.5967 ms.

The degree of genetic divergence using Mahalanobis's D(2) statistic and the clustering pattern using canonical variate analysis between Sahiwal and its 39 Friesian grades were studied for 9 characters of economic importance. The records were adjusted for the significant effects due to farms, periods and seasons. Forty grades were grouped into 11 clusters. The results have shown that in cattle when two breeds of diverse origin, one of superior merit and the other relatively inferior, are crossed in a scheme of forward crossing, there is no linear increase in production level above 50% with the increase in genes of the superior parent. It can not be assumed that grading up to a total replacement of genes will lead to higher levels of production at least in cattle. In order to stabilize a breed type from such a crossbred population a breeding plan has been proposed.

An experiment to search massive long-lived, weakly interacting particles (leptons) in cosmic radiation has been conducted at Kolar Gold Fields at a depth of 7.6 hg cm−2 (1 hg cm−2=100 g cm−2) below surface. The apparatus was senstive to sub-relativistic (velocity 0.75 c) by using a water Cerenkov detector. The range of the particle is observed in arrays of neon flash tubes interspersed with iron absorbers. During 3000 hours of observation 28 events were recorded satisfying the trigger and event selection criteria. Bulk of these events were interpreted as due to recoil protons (low energy) from the inelastic scattering of high energy muons in the overhead absorber. The remaining events were interpreted as either atmospheric stopping protons or stopping muons that failed to generate a Cerenkov signal. The observed events are thus consistent with the background and no heavy leptons were seen. From our observations an upper limit of 2.12×10−7 (with 90% confidence level) is set on the ratio of the flux of heavy leptons to that of all muons at this depth.

The Crab pulsar, a source of pulsed photons over a wide range of energies, has been observed in the TeV energy range by several groups using the Atmospheric Cerenkov technique1. Time-averaged phasograms have shown signals on only a few occasions. The Durham University group2 detected pulsed TeV γ-rays during two transients lasting 15 min, each in October, 1981, while the Ooty group3,4 has shown that the transient duration could be on time scales of minutes or even seconds. In our recent observations, we identified a 15-min interval on 23 January 1985 during which pulsed TeV γ-rays were detected at a 5.1 sigma level at the same phase as the radio main pulse. Our inference of transient pulsed emission is strengthened by the absence of a signal in a nearby control telescope tilted 8° away from the pulsar and evidence for signal in another telescope 11 km away. We present here an analysis of the data from our 1984–1985 observations.

We report here the details of an experiment carried out at mountain altitude, at Ootacamund (2.2 km above sea level), India between March 1977 and March 1979, to detect bursts of high energy (∼ 5 × 1013 eV) γ rays from celestial sources. Not having detected any such bursts, we give 99% confidence level upper limits both to their flux and to the primordial mini-black hole explosion rate in the vicinity of the Solar System.