004297   Maartens R (Relativity and Cosmology Group, School of Computer Science and Mathematics, Portsmouth University, Portsmouth PO1 2EG, Britain, UK) : Cosmological magnetic fields. Pramana J Phys 2000, 55(4), 575-83.

Magnetic fields are observed not only in stars, but in galaxies, clusters, and even high redshift Lyman-α systems. In principle, these fields could play an important role in structure formation and also affect the anisotropies in the cosmic microwave background radiation (CMB). The study of cosmological magnetic fields aims not only to quantify these effects on large-scale structure and the CMB, but also to answar one of the outstanding puzzles of modern cosmology: when and how do magnetic fields originate? They are either primordial, i.e. created before the onset of structure formation, or they are generated during the process of structure formation itself.

30 ref

004296   Dhurandhar S V (NO, Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Post Bag 4, Pune-411 007) : Searching for gravitational waves from rotating neutron stars. Pramana J Phys 2000, 55(4), 545-58.

Rotating neutron stars are one of the important sources of gravitational waves (GW) for the ground based as well as space based detectors. Since the waves are emitted continously, the source is termed as a continuous gravitational wave (CGW) source. The expected weakness of the signal requires long integration times (<126> year). The data analysed problem involves tracking the phase coherently over such large integration times, which makes it the most computationally intensive problem among all GW sources envisaged. The general problem of the data analysis is discussed, and more so, in the context of searching for CGW sources orbiting another companion object. The problem is important because there are several pulsars, which could be deemed to be CGW sources orbiting another companion star. Differential geometric techniques for data analysis are described and used to obtain computational costs. These results are applied to known systems to assess whether such systems are detectable with current (or near future) computing resources.

27 ref

004295   Banerjee A;Tavakol R (Department of Physics, Jadavpur University, Calcutta-700 032) : Workshop IV - cosmology - theoretical models/alternative scenarios. Pramana J Phys 2000, 55(4), 603-7.

003220   Sharma J P;Singh P K (Department of Applied Sciences, M M M Engineering College, Gorakhpur-273 010) : Relativistic structure of white dwarfs. Indian J Phys-Pt B 2000, 74(5), 345-9.

An analytic approach has been used to study the special relativistic features of degenerate configurations, such as the white dwarfs, governed by the equation of state P = Af(x) (A = constant = πm⁴c⁵/3h³). Approximate analytical solutions to the equations of hydrostatic equilibrium, suitable for use in short computer programmes or on small calculators, have been given. Results of calculations for few physical parameters are given in tabular and graphical forms. Approximate analytical results are very close to the previous numerically calculated values.

37 ref

003219   Marhas K K;Goswami J N (Physical Research Laboratory, , Navarangpura, Ahmedabad-380 009) : Boron isotopic composition in early solar system solids. Curr Sci 2000, 78(1), 78-81.

Abundance and isotopic composition of boron (B) are determined in refractory silicate phases from the primitive carbonaceous chondrite Efremovka using an ion microprobe. These refractory phases represent some of the earliest solids to condense from the solar nebula. All the analysed phases (anorthite, melilite and fassaite) have very low B content ranging from 0.1 to 1.3 ppm; anorthite has relatively higher B content than melilite and fassaite. The measured values of the ¹¹B/¹⁰B ratio in anorthite grains are similar and indistinguishable from the normal ratio of 4.04558 within experimental uncertainties. This is at variance with the reported large magnitude B isotopic anomalies within individual meteoritic chondrules whose formation in the nebula postdates refractory silicates. Although B isotopes could have been homogenized during the formation of refractory phases, plausibility considerations suggest that our data are consistent with a uniform distribution of B isotopes of normal composition in the solar nebula.

25 ref

003218   Gothe K S et al (NO, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005) : Automatic computerised telescope orientation system for the VHE gamma ray experiment at Pachmarhi. Indian J pure appl Phys 2000, 38(4), 269-79.

Inexpensive and automatic computerised telescope orientation system (ACTOS) developed in-house has been described, which controls the orientation and tracking of all the old Pachmarhi array of Cerenkov telescopes consisting of 46 parabolic mirrors, mounted on 22 independent equatorial mounts. This PC-based system has a mean pointing accuracy of 0°.1 in both E-W and N-S direction. Earlier the array was controlled by a system of gears, driven by stepper motors one each in East-West (E-W) and North-South (N-S) directions. ACTOS was designed specially for the experiment being conducted at Pachmarhi (India) to search for very high energy (VHE) gamma rays from celestial sources.

001068   Kashyapi A;Shaha S K (NO, Meteorological Office, Pune-411 005) : Total solar eclipse of 1995: observations on plants' phenological behaviour and birds' activity. Mausam 1999, 50(4), 401-3.

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001067   Rawat D K;Agrawal N C;Bais V S (Lab. of Environmental Biology, Department of Zoology, Doctor Harishing Gour Vishwavidyalaya, Sagar-470 003) : Alterations in endosulfan and Triazophos toxicity on Heteropneustes fossilis (Bloch.) in relation to pH and hardness of water. J Nat Conserv 2000, 12(1), 51-6.

Bioassay tests for the determination of LC50 values of an organochlorine (Endosulfan) and an organophosphate pesticide (Triazophos) were commenced on a cat fish, H. fossilis (Bloch) using 10 cocentrations of each pesticide at different pH (7.5 and 10.0 unit) and hardness levels (100 and 200 mg/l of water) The results were observed after 24, 48, 72 and 96 hrs. Dramatical changes in the physical behaviour of fish were recorded in each of pesticide when the concentration, exposure period and pH and harness of test water were concerned.

24 ref

021394   Sengupta S (Department of Gology and Geophysics, Indian Institute of Technology, Kharagpur) : Mapping of forest cover using remote sensing. Res Innovation 2002, 8, 13-16.

Present investigation is to prepare a base map of this area showing the administrative divisions, cultural features, road network and drainage patterns. Also generation of a map showing forest types and species from two season satellite image is attempted.

3 illus

020337   Vishwanath P R (Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400 005) : European sightings of the crab supernova. Curr Sci 2001, 81(11), 1394-5.

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020336   Singh R N (Department of Applied Physics, Institute of Technology Banaras Hindu University, Varanasi-221 005) : On the probable existence of life on mars. Curr Sci 2001, 81(11), 1400-01.

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020335   Sharma S;Narayan A (Department of Mathematics, Bhilai Institute of Technology, Durg (C.G.)-491 001, ) : Effect of solar radiation pressue on the motion and stability of inter-connected satellites system in orbit. Indian J pure appl Math 2002, 33(5), 609-623.

Effects of the Earth shadow on the motion and stability of two satellites connected by light flexible and inextensible string in the central graviational field of the Earth, under the influence of solar pressure has been studied. The equations of motion of the system have been deduced with respect to the centre of mass of the system, which is assumed to move along Keplerian elliptic orbit (in particular Circular). The osculating plane of the orbit of the centre of mass has been supposed to be inclined at a constant angle with respect to the plane of the ecliptic. It has been established that the particular solutions of the nonlinear, non-autonomous and non-homogenous differential equations of relative motion, remain stable, if the parameter of solar pressure lies within a certain limit.

4 illus, 3 tables, 22 ref

020334   Bhattacharya P M;Majumdar R K;Kayal J R (Central Geophysics Division, Geological Survey of India, 27, Chowringhee Road, Lp;lata-700 016) : Fractal dimension and b-value mapping in northeast India. Curr Sci 2002, 82(12), 1486-91.

The statistical characteristics of seismicity, fractal dimension and b-values are mapped in the NE India region using permanent microearthquake network data and teleseismic data. The maps revealed the seismogenic structures and the crustal heterogeneities, which are useful for earthquake risk evaluation.

4 illus, 31 ref

019327   Satyanarayana M;Veerabuthiran S;Ramakrishna Rao D;Presennakumar B;Sreelatha P;Appu K S (Space Physics Laboratory, Vikram Sarabhai Space Centre, , Trivandrum-695 022) : Solar eclipse induced changes in aerosol extinction profiles : a case study of 11 Aug. 1999 solar eclipse using lidar at a tropical station Trivandrum, India. Indian J Radio Space Phys 2002, 31(2), 82-7.

Experiment has been conducted to understand the 11 Aug. 1999 solar eclipse induced changes in the aerosol extinction coefficient in the troposphere and the lower stratosphere using the multiwavelength lidar system designed and developed in-house at a tropical station Trivandrum (8° 33'N, 77° E). Results of the measurements reveal an increase in aerosol extinction coeffient in the troposphere and a decrease in the lower stratosphere compared to control day. Six high altitude baloon ascents with 1680 MHZ radiosonde were conducted from Thumba to study the eclipse induced variations in winds and temperature of the lower atmosphere. The study clearly reveales the cooling of the entire troposphere layers with maximum of 5°C occurring below 15 km altitude. The changes in the temperature and the relative humidity during the eclipse are the key factors contributed for the observed aerosol extinction coefficient.

3 illus, 15 ref

019326   Rastogi R G;Stening R J (Department of Physics, Gujarat University, Ahmedabad-380 009) : Eastward geomagnetic field variations at electrojet stations. Indian J Radio Space Phys 2002, 31(2), 67-74.

Describes the daily and seasonal variations of declination (or eastward geomagnetic field) at five equatorial electrojet observatories operating during 1958. The daily variation of declination in Central Asian sectors (Addis-Ababa and Trivandrum) showed a completely opposite character between the two solstices. The daily variation of declination at Huancayo showed a strong daytime peak during any of the seasons and at Jarvis during March and December. These abnormalities are suggested to be due to the different ionospheric electric conductivity profiles and due to complex dynamics caused by varying interaction between geographic and magnetic equators at different longitudes.

7 illus, 1 table, 31 ref

019325   Lakshmi D R;Reddy B M (National Physical Laboratory, , New Delhi-110 012) : Space weather issues relevant to India. Proc Indian Natn Sci Acad-Pt A 2002, 68(1), 1-19.

Dependence on sophisticated space based technological systems is increasing rapidly not only in communications, but also in a number of critical applications. All of these space based systems are vulnerable to changing conditions in space environment. It is essential to understand and if possible to predict the rapid changes in these conditions presently known as `Space Weather'. There is a need to know both on long term and short term scales the limitations imposed by space weather fluctuations on the efficacy of operation of satellites and satellite based systems. While there has been a significant understanding of solar origin of such events as CMEs, magnetic storms and Solar particle events; the coupling between the solar induced events and various terrestrial atmospheric regions is little understood. Such ignorance is exemplified by the recent discovery of very large O⁺ ion content in the ring current during intense magnetic storms where acceleration mechanisms of eV range ionospheric ions to MeV range challenges the existing theories. The review briefly outlines the development of this subject during the recent decades.

10 illus, 70 ref

014031   Majumdar D (Theory Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700 064) : SNO results and neutrino magnetic moment solution to the solar neutrino problem. Pramana J Phys 2002, 58(1), 135-45.

Analyses the solar neutrino data obtained from chlorine, gallium and Super-Kamiokande (SK) experiment (1258 days) and also the new results that came from Sudbury Neutrino Observatory (SNO) charge current (CC) and elastic scattering (ES) experiments considering that the solar neutrino deficit is due to the interactio of neutrino transition magnetic moment with the solar magnetic field. Also analyses the moments of the spectrum of scattered electrons at SK. Another new feature in the analysis is that for the global analysis is replacement of the spectrum by its centroid.

2 tables, 18 ref

014030   Chakraborty S (Department of Mathematics, Jadavpur University, Kolkata-700 032) : Quantum cosmology in Ashtekar variables with non-minimally coupled scalar-tensor theory. Pramana J Phys 2002, 58(1), 1-12.

Using non-minimally coupled scalar-tensor theory in homogenous and isotropic cosmological model, quantum cosmology has been developed for Ashtekar variables. The wave function has been evaluated by solving the Wheeler-Dewitt (WD) equation and also using path integral formulation. Semi-classical limit using WKB approximation has also been discussed. Finally, the quantum Bohmian trajectories has been studied in detail.

16 ref

012918   Vasundhara R;Jayakumar K;Velu C;Appakutty M; Paranjpye A;Kulkarni H;Nitsure P;Prabhunne M;Shah K (Indian Institute of Astrophysics, , Bangalore-560034) : Observations of occultation of HIP 66446 by (423) diotima on 2001 March 15 from India - Detection of a companion to the star. Bull Astr Soc India 2001, 29(4), 577-84.

Observations of the occultation of the star HIP 66446 by (423) Diotima on 2001 March 15 made by the team at the Vainu Bappu Observatory and three mobile teams at Ganeshgudi, Londa and the CES Field Research Station at Sirsi are presented. Makes a preliminary estimate of 186 km X 149 km for the projected size of the asteroid. The immersion and emersion events occurred in two stages revealing the binary nature of the star for the first time. The derived integrated brightness ratio of the stars from the two step immersion and the emersion events is found to be 1.33 ± 0.27. The projected separation between the two components along the track, i.e. along the direction 115° from North, is found to be 28 km or 0.018 ± 0.002 arcsec.

2 illus, 2 tables, 17 ref

012917   Vasundhara R et al (Indian Institute of Astrophysics, , Bangalore-560 034) : CCD observations of mutual events of jovian satellites from VBO during 1997. Bull Astr Soc India 2001, 29(4), 511-18.

CCD observations of the mutual events of the Galilean satellites of Jupiter from the Vainu Bappu Observatory during 1997 are presented. The derived times of close approach of the geometric centers of the satellites (satellite & shadow center) for the mutual occultations (mutual eclipses) are compared with the predictions. The residuals in observed times can be directly used to derive the relative longitude corrections of the two satellites involved in the mutual event. In the data set, the (O-C) in longitudes of the 3O2 and 3E2 events indicate a delay in longitude of Europa or Ganymede by ≈ 19 km.

1 illus, 2 tables, 13 ref

012916   Sagar R;Naidu B N;Mohan V (Indian Institute of Astrophysics, , Bangalore-560 034) : A deep VI CCD photometric study of the neglected galactic star cluster NGC 6631. Bull Astr Soc India 2001, 29(4), 519-30.

Presents the VI CCD photometric observations of about 5500 stars up to a limiting magnitude of V <126> 20 in an area of <126> 16' X 16' around the cluster NGC 6631. The cluster parameters determined for the first time by fitting the theoretical isochrones in the V, (V-I) diagram of the cluster stars are E(V - I)=0.60±0.05 mag, distance = 2.6<145>0.5 kpc, age = 400±100 Myr and metallicity, Z = 0.05. The cluster diameter determined from the radial density profile is 4.8±0.5 pc. The mass function of the cluster has a slope of 2.1±0.5.

6 illus, 4 tables, 13 ref

012915   Nagarjaa Naidu B;Srinivasan R;Mohan V;Sagar R (NO, Indian Institute of Astrophysics, Bangalore-560034) : Performance of the IIA mosaic CCD camera system. Bull Astr Soc India 2001, 29(4), 545-6.

Evaluates performance of the 4K X 4K mosaic CCD camera system developed at the Indian Institute of Astrophysics using four Thomson CCDs in a buttable configuration. The camera system consists of a mosaic CCD dewar developed to mount the four CCDs and an electronics controller designed to control the mosaic configuration. A window based data acquisition software is used to configure the controller and acquire images from the camera. The calibration measurements indicate that all 4 CCDs have similar characteristics with a gain of about 3.9e/ADU, rms noise of <126> 19 e, full-well capacity of <126> 57000 ADU, non-linearity of <126> 0.4% aand peak quantum efficiency of <126> 40% in the red region. The problem of cross-talk is faced in this multi-readout system and a solution is offered. The performance of the mosaic CCD camera has been found satisfactory at the telescope.

13 illus, 3 tables, 9 ref

012914   Murthy J;Henry R C;Paxton L J;Price S D (Indian Institute for Astronomy, , Koramangala, Bangalore-560 034) : MSX observations of diffuse UV emission in orion. Bull Astr Soc India 2001, 29(4), 563-75.

Observed intense diffuse radiation in the UV (1400 Angstrom - 2600 Angstrom) from three fields around M42 in Orion. Intensities of 20000 photons cm^-2 sr^-1 s^-1 Angstrom^-1 were observed to the east and west of M42 with 8000 photons cm^-2sr^-1S^-1 Amgstrom^-1 south of the nebula. Enhanced emission, perhaps associated with a nearby complex of molecular clouds observed in CO, was detected in one of the fields. The IRAS 100 μm emission in that region is highly correlated with the UV intensity with a UV-IR ratio of 40 photons cm^-2 sr^-1s^-1 Angstrom^-1 (MJy sr^-1)^-1. In the other two fields there was no structure in the diffuse emission nor was there any correlation with the IRAS emission.

7 illus, 2 tables, 9 ref

012913   Joshi Y C;Pandey A K;Narasimha D;Sagar R (State Observatory, , Manora Peak, Naini Tal-263 129) : Search for microlensing events towards M31 galaxy. Bull Astr Soc India 2001, 29(4), 531-44.

M31, the prominent galaxy of the Local Group, is located at a distance of about 700 kpc. Due to its convenient orientation, it is an alluring target for gravitational microlensing to search for massive astrophysical compact halo objects (MACHOs), in both the Galactic halo and its own halo. Carries out the observations of the suburb of M31 galaxy using the 104-cm Sampurnanand Telescope of the State Observatory, Naini Tal, India. The observations have been accumulated for about hundred nights spanning over 800 days during 1998-2001. After the initial tests and preliminary analysis of the first two years data have detected some possible M31 Cepheid variables of period between 10 to 85 days. Also using pixel method have got an irregular variable and further analysis is in progress to detect the lensing events in the observed region.

6 illus, 2 tables, 22 ref

008657   Rekhesh Mohan;Dwarakanath K S;Srinivasan G; Chengalur J N (NO, Raman Research Institute, Bangalore-560 080) : GMRT observations of interstellar clouds in the 21cm line of atomic hydrogen. J Astrophys Astr 2001, 22(1), 35-50.

Nearby interstellar clouds with high (<157>v<157> ≥ 10 km s^-1) random velocities although easily detected in NaI and CaII lines have hitherto not been detected (in emission or absorption) in the HI 21cm line. Describes deep Giant Meterwave Radio Telescope (GMRT) HI absorption observations toward radio sources with small angular separation from bright O and B stars whose spectra reveal the presence of intervening high random velocity CaII absorbing clouds. In 5 out of the 14 directions searched, detected HI 21cm absorption features from these clouds. The mean optical depth of these detections is <126> 0.09 and FWHM is <126> 10 km s⁰¹, consistent with absorption arising from CNM clouds.

6 illus, 3 tables, 19 ref

008656   Kantharia N G;Anantharamaiah K R (NO, National Centre for Radio Astrophysics (TIFR), Pune-411 007) : Carbon recombination lines from the galactic plane at 34.5 and 328 MHz. J Astrophys Astr 2001, 22(1), 51-80.

Present the results of a search for carbon recombination lines in the Galaxy at 34.5 MHz (C575α) made using the dipole array at Gauribidanur near Bangalore. Observations made towards 32 directions resulted in detections of lines in absorption at nine positions. Followup observations at 328 MHz (C272α) using the Ooty Radio Telescope detected these lines in emission. A VLA D-array observation of one of the positions at 330 MHz yielded no detection implying a lower limit of 10' for the angular size of the line forming region. The longitude-velocity distribution of the observed carbon lines indicate that the line forming regions are located mainly between 4 kpc and 7kpc from the Galactic centre. It has been found that the angular size of the line forming regions is ≥ 4°, then the range of parameters that fit the data are: T_e = 20 - 40 K, n_e % 0.1 - 0.3 cm^-3 and pathlengths <126> 0.07 - 0.9 pc which may correspond to thin photodissociated regions around molecular clouds. On the other hand, if the line forming regions are <126> 2° in extent, then warmer gas (T_e <126> 60 - 300 K) with lower electron densities (n_e <126> 0.03 - 0.05 cm^-3 extending over several tens of parsecs along the line of sight and possibly associated with atomic Hi gas can fit the data.

5 illus, 8 tables, 47 ref

008655   Griffin R F (Observatories, , Madingley Road, Cambridge CB3 OHA, England) : Spectroscopic binaries near the north galactic pole paper 23: HD 111154. J Astrophys Astr 2001, 22(1), 121-30.

HD 111154 is a member of the Coma Cluster. It is here shown to be a somewhat unequal pair of stars of approximately solar type. They are in an orbit that has a period of just under 27 days and quite a high eccentricity (0.442). Although the minimum masses (1.08 and 1.00 M.) are large enough to encourage a search for eclipses, no such events have been detected.

2 illus, 2 tables, 15 ref

008654   Dwarakanath K S;Owen F N (NO, Raman Research Institute, Bangalore-560 080) : GMRT detection of HI 21 cm-line absorption from the peculiar galaxy in abell 2125. J Astrophys Astr 2001, 22(1), 1-8.

Giant Meterwave Radio Telescope 4 has been used to detect the HI 21 cm-line absorption from the peculiar galaxy C 153 in the galaxy cluster Abell 2125. The HI absorption is at a redshift of 0.2533, with a peak optical depth of 0.36. The full width at half minimum of the absorption line is 100 km s^-1. The estimated column density of atomic hydrogen is 0.7x10²² (T_s/100) cm^-2. The HI absorption is redshifted by <126> 400 km s<>^>-1 compared to the [OIII] emission line from this system. Attributed this to an infalling cold gas, or to an out-flowing ionised gas, or to a combination of both as a consequence of tidal interactions of C153 with either a cluster galaxy or the cluster potential.

2 illus, 14 ref

008653   Ashoka Kumar B N;Babu V C;Seetha S;Girish V; Gupta S K;Ramsagar;Joshi S;Narang P (NO, ISRO, Satellite Center, Airport Road, Bangalore-560 017) : Development of a three channel photometer for UPSO, Naini Tal. J Astrophys Astr 2001, 22(1), 131-44.

The design and performance of a portable three channel photometer installed at the Uttar Pradesh State Observatory (UPSO), Nainital is described. The photometer is modular and the whole unit can be disassembled as individual channels such that the system can also be used as a single channel or two channel photometer. The system also has provision to monitor a guide star. The instrument was put into operation since November 1999 on the 1m Sampurnanand telescope at UPSO, Nainital. Since then, it is used extensively for the `Survey of rapidly oscillating Ap (roAp) stars in the northern sky' from UPSO. observational results using this new photometer in its initial phase of operation are discussed. The advantage of having continuous sky measurement is demonstrated.

3 illus, 7 ref

008652   Anish Roshi D;Anantharamaiah K R (National Centre for Radio Astrophysics, TIFR, Pune) : Hydrogen recombination lines near 327 MHz - II. a galactic plane survey with a 2° x 6' beam. J Astrophys Astr 2001, 22(1), 81-119.

Present the results of a higher resolution (2° x 6') survey of RRLs from seven 2°-wide fields and two 6°-wide fields in the same longitude range. Observations were made using the Ooty Radio Telescope (ORT). A total of 252 spectra that were obtained are presented. RRLs were detected in almost all the individual positions within the fields with l <60> 35° and at several individual positions within the fields in the longitude range l = 35° to 85°. Detailed analysis of the data towards the field centered at G45.5+0.0, shows that the line emission consists of discrete zones of ionized gas. The angular extent of these zones are likely to be one degree or more corresponding to a linear size of <62> 110 pc at the kinematic distance.

19 illus, 4 tables, 31 ref

006638   Yousuf Zai M A K;Quamar J (NO, Institute of Space and Planetary Astrophysics (ISPA), University of Ka, Karachi-75270) : Study of phenomenon of ozone layer depletion as a physical process. Indian J Phys-Pt B 2001, 75(4), 307-14.

Ozone (O3) is the most important trace constituent of the stratosphere. Incidents such as the industrial emissions of CFCs, supersonic transports and volcanic eruptions provide a most visible example of global unbalance in our natural ecology. Among other scientific and socio-economic fallouts from this, the aggravation of the phenomenon of ozone layer depletion (OLD) is particularly disturbing. Events like 1987 Montreal Protocol explain the magnitude of the threatening status of the OLD. For OLD analysis, to overcome doubts of the effectiveness of the mathematical formulation against the empirical relation, this work studies the formulation of the phenomenon of OLD as a physical process, with special reference to the stratospheric region of Pakistan. Establishes the results of preliminary calculation reported elsewhere, confirming quantitatively the phenomenon of OLD.

8 illus, 37 ref

006637   Singh A K (Department of Physics, Maharaja College, V.K.S. University, Arrah-802 301) : Study of ionosphere - magnetosphere coupling using whistler data. Indian J Phys-Pt B 2001, 75(4), 321-5.

Whistler mode wave propagation through the magnetosphere is facilitated by the formation of ducts caused by latitudinal variation (enhancement) of electron density through the process of interchange of flux tube or perturbation produced by electric field. The enhanced electron density decays by the process of diffusion across and along the magnetic field. Charged particles have much greater mobility along the magnetic field lines as compared to that across the field line and hence diffuse along the field line from the magnetosphere to the ionosphere and as a result, coupling of magnetosphere to the ionosphere is established. Whistler data is used to calculate the equatorial electron density and total electron content in a flux tube of unit cross section at the reference height. The time of development of electron flux yields downwards/upward movement of flux. The transported flux during geomagnetically disturbed and quiet condition is evaluated. The whistler data recorded at Indian station Varanasi and Gulmarg are used in the study. The refilling of ionosphere by the flux transported from the plasmasphere is discussed in the light of other available measurements.

5 illus, 14 ref

006636   Sharma A K;Chandra S;Behere S H (NO, School of Physical Sciences, S.R.T.M. University, Nanded-431 606) : Calculation of potential curve of A<. Indian J Phys-Pt B 2001, 75(5), 477-80.

On calculating the RKR potential energy curve for A¹Σ⁺ state of ⁷LiH, by using the Dunham coefficients. Finds an unsual situation that around v' = 14, the vlaue of rmin starts to increase.

^ssc3 tables, 7 ref

006635   Saha S K;Maitra D (NO, Indian Institute of Astrophysics, Bangalore-560 034) : Auto-correlation of binary stars. Indian J Phys-Pt B 2001, 75(5), 391-5.

Speckle interferometric techniques is used to record a series of short exposure images of several close binary stads with subarcsecond separation through a narrow band filter centred at Hα at the Cassegrain focus of the 2.34 meter (m) Vainu Bappu telescope (VBT), situated at Vainu Bappu Observatory (VBO), Kavalur. The auto-correlation method is developed under Image Reduction Analysis Facility (IRAF). Wiener filter is included in the programme to eliminate spurious high frequency contributions; a few sets of data provide the optimised results. The auto-correlated image of these stars gives the separation of the binary components.

1 illus, 25 ref

006634   Saha S K (NO, Indian Institute of Astrophysics, Bangalore-560 034) : Observation of a magnetic sub-storm event in the equatorial thermosphere-suggestion for interpretation. Indian J Phys-Pt B 2001, 75(4), 285-9.

Equatorial peak atomic oxygen density in the lower thermosphere (around 100 km) is seen to be moderately enhanced following a magnetic sub-storm using data obtained from the ground based observations. The temperature of the mesopause obtained from OH(7-2) night airglow observation has shown a rise similar to the positive bay of the magnetic field intensity (horizontal component) during the said disturbance. There is no enhancement of OI(6300) intensity around 300 km compared to the OI(5577) rise. The implication of these observation is discussed in the light of the extra-ionospheric current, increasing the recombination rate.

4 illus, 38 ref

006633   Neerja;Gupta G P;Tripathi A N;Msezane A Z (Department of Physics, University of Roorkee, Roorkee-247 667) : Energy levels, oscillator strengths and lifetimes in Cl VI. Indian J Phys-Pt B 2001, 75(5), 407-11.

Energy levels have been calculated with oscillator strengths and transition probabilities for all dipole-allowed transitions among the 24 terms belonging to the (1s²2s²2p⁶)3s3p, 3p², 3s², 3s3d, 3s4s, 3p3d, 3s4p, 3s4f and 3p4s configurations of Cl VI in the LS coupling scheme. Included fairly large number of configurations in the configuration-interaction expansions to ensure convergence. The calculated energy levels are in close agreement with laboratory measurements. From transition probabilities, have also calculated radiative lifetimes of 12 singlet and 10 triplet states in Cl VI. Results are compared with the other available theoretical results.

3 tables, 20 ref

006632   Mehra M;Bhatnagar K B (Department of Mathematics, A.R.S.D. College, New Delhi) : Ground trace of a satellite moving under the gravitational forces of the sun, the moon, the earth and the solar radiation pressure. Indian J pure appl Math 2001, 32(6), 827-44.

Theory for the ground trace of a satellite moving under the gravitational forces of the sun, the moon, the earth (including ellipticity of the earth's equator) and the solar radiation pressure has been developed. The ground trace has been drawn in the cases orbit in the reference plane and orbit in the equatorial plane. Both the above cases have been studied for J⁽²⁾2 = 0, q = 1, J⁽²⁾2 = 0, q = 1, J⁽²⁾2 = 0, q # 1, J⁽²⁾2 # 0, q # 1 (J⁽²⁾2 = equatorial ellipticity of the earth, q = solar radiation parameter). It is shown that the graphs take the shape of crossing the equator twice, due to earth's equatorial ellipticity (<157> <**> <157> = 90°, q = 1) alone or the solar radiation pressure (q = 0.9) alone or taking into account both the effects, the ground trace shrinks itself in the direct of the latitude of the satellite and this change is more due to solar radiation pressure than due to earth's equatorial ellipticity.

14 illus, 6 tables, 6 ref

006631   karki B P;Sinha S K (Department of Physics, L S College, B B A Bihar University, Muzaffarpur-842 001) : Theory for transport properties of molecular fluids of non-spherical molecules. Indian J Phys-Pt B 2001, 75(4), 327-32.

Effective diameter hard sphere theory is employed to estimate the transport properties of molecular fluids of non-spherical molecules interacting via the hard Gaussian overlap and Gaussian overlap with constant energy (GOCE) potentials. The transport properties (TP's) of the molecular fluids are expressed in terms of a hard sphere (HS) fluid of properly chosen effective hard sphere diameter. The explicit expressions for the shear viscosity and thermal conductivity for the HS fluid are given. The theory is applied to estimate the TP's fluid of the hard ellipsoid of revolution N2 and C6H6. The agreement is found to be fairly good.

4 illus, 17 ref

006630   Gupta S V (National Physical Laboratory, , New Delhi-110 012) : New water density table at ITS 90. Indian J Phys-Pt B 2001, 75(5), 427-32.

Different expressions, for relative density of water versus temperature, used by various researchers since 1890 have been reviewed. Recently, a good amount of work for determination of absolute or relative density of water as a function of temperature, with clear understanding of the effects of isotopic composition and air saturation on density of water, has been carried out. The results have been fitted into a fairly variety of functions. This has added to confusion to user scientist. To circumvent this problem, a harmonized expression for relative density of water satisfying the available data, has been derived. The internationally agreed value, of maximum density and the temperature at which it is maximum are respectively. 999.974950 kg/m³ and 3.983035°C. As the isotopic composition of water from various sources varies, the isotopic composition of standard Mean Ocean Water (SMOW) has been specified. A unique expression giving the difference in density of SMOW and sample water has been stated. The decrease in density due to different air saturation and temperature has been derived. Water density table for SMOW using internationally agreed values of various parameters and ITS 90 has been constructed from 0 to 41°C in steps of 0.1°C.

1 table, 26 ref

006629   Dwivedi A K;Varma P;Tiwari M S (Department of Physics, Dr H S Gour University, Sagar-470 003) : Kinetic alfven wave with general loss-cone distribution function in the presence of ion and electron beam. Indian J Phys-Pt B 2001, 75(5), 447-53.

Dispersion relation, current and growth rate with marginal instability criteria of the kinetic Alfven wave with general loss-cone distribution function in a low β inhomogeneous plasma in the presence of ion and electron beam, have been obtained by evaluating the trajectories of the charged particles. The whole plasma is considered to consist of resonant and non-resonant particles. It is assumed that non-resonant particles support the oscillatory motion of kinetic Alfven wave while the resonant particles participate in the energy exchange with the wave. The effects of steepness of loss-cone distribution in the presence of ion and electron beam are discussed on the dispersion relation, current and growth-rate of the instability. The applicability of the investigation is discussed for auroral phenomena during the substorm periods.

6 illus, 29 ref

006628   De Matos C J;Tajmar M (NO, , ESA-ESTEC, Postbus 299, NL-2200 AG NOordwijk, The Netherlands) : Gravitomagnetic Barnett effect. Indian J Phys-Pt B 2001, 75(5), 459-61.

Using the linearized theory of general relativity, the gravitomagnetic analogue of the Barnett effect is derived. Further theoretical and experimental investigations are recommended, due to the microscopic values the equivalent gravitomagnetic field involved in this effect and to the constraints which would appear on quantum theories of gravity, currently under development, in case of non-detection of the predicted phenomena.

1 illus, 8 ref

006627   Choudhury S;Dutta Majumder D (Machine Intelligence Unit, Indian Statistical Institute, 203, B.T. Road, Kolkata-700 035) : Impact of pre-monsoon thunderstorm on tropospheric VHF propagation. Indian J Phys-Pt B 2001, 75(4), 297-305.

Thunderstorms which occur during the pre-monsoon season are the most common kind of storms over the eastern region of India. Onset and departure of these storms bring large scale changes in the thermodynamic state of the lower atmosphere. Studies the impact of these pre-monsoon thunderstorms on tropospheric propagation of 188 MHz TV signal over a 70 km path situated between Satkhira TV station in Bangladesh and Electronics and Communication Science Unit of Indian Statistical Institute, Kolkata (India). The propagation characteristics of 188 MHz TV signal observed on stormy days are compared with those which observed during the normal days of the same season. It is observed that these pre-monsoon thunderstorm bring a noticable change in fading characteristics of the 188 MHz VHF signal. In addition to this, SODAR observations and radiosonde data are analysed to study the radioclimatology during these stormy days and obtained results are compared with that observed during the normal days of the same season.

16 illus, 11 ref

006626   Choudhury S (Machine Intelligence Unit, Indian Statistical Institute, 203 B B.T. Road, Kolkata-700 035) : Tropospheric VHF signal level variation : estimation of monthly and seasonal behavior of scintillation index. Indian J Phys-Pt B 2001, 75(4), 291-6.

Fluctuations in the signal strength of 188 MHz TV signal (transmitted regularly from Satkhira TV station Bangladesh from 1630 hours to 2230 hours) have been recorded at Electronics and Communication Science Unit of Indian Statistical Institute of investigate the propagation characteristics of radiowaves over the eastern region of India. Recorded VHF signal levels are analyzed to estimate the percentage occurrence of scintillation index (SI) (which in turn, provide information regarding the change in refractive index of the propagating medium) for the different months and seasons over this region. In addition to this, the distribution of average value of VHF scintillation index with respect to period of observation for all the twelve months and four different seasons over the site of experiment is also estimated. The obtained results show a significant discrepancy in monthly and seasonal behaviour of scintillation of VHF signal. Attempt has been made to explain these discrepancies on the basis of radioclimatological condition over the eastern coastal region of India.

7 illus, 19 ref

004477   Cucka P;Duric Z;Rivlin E;Rosenfeld A (Computer Vision Laboratory, Center for Automation Research, University of Maryland, College Park, MD 20742-3275 (USA)) : Qualitative description of camera motion and scene depth from histograms of normal flow. Proc Indian Natn Sci Acad-Pt A 2001, 67(2), 145-56.

Time-varying histogram can be used to derive qualitative information about the observer's motion - for example, whether it is (primarily) translational or rotational, and whether the direction of translation or axis of rotation is (roughly) parallel or perpendicular to the camera axis. This is illustrated using flow histograms obtained from a variety of real image sequences. If the motion is translational, qualitative information about the scene depth can also be obtained from the flow histograms-for example, whether the scene depth is unimodal or bimodal. This is illustrated for real scenes containing a layer of vegatation seen against a textured background, or two layers of vegetation.

14 illus, 30 ref

001155   Lortan D B;Maharaj S D;Dadhich N K (NO, School of Mathematical and Statistical Sciences, University of Natal, Durban-4041, South Africa) : Inheriting geodesic flows. Pramana J Phys 2001, 56(6), 715-22.

Investigates the propagation equations for the expansion, vorticity and shear for perfect fluid space-times which are geodesic. It is assumed that space-time admits a conformal Killing vector which is inheriting so that fluid flow lines are mapped conformally. Simple constraints on the electric and magnetic parts of the Weyl tensor are found for conformal symmetry. For homothetic vectors the vorticity and shear are free; they vanish for nonhomothetic vectors. proves a conjecture for conformal symmetries in the special case of inheriting geodesic flows : there exist no proper conformal Killing vectors (ψab ≠ 0) for perfect fluids except for Robertson - Walker space-times. for a nonhomothetic vector field the propagation of the quantity in (Rabu^au^b) along the integral curves of the symmetry vector is homogeneous.

21 ref

000040   Singh K P (Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005) : Peering into the hearts of galaxies. Curr Sci 2001, 81(1), 25-31.

Composed of hundreds of billions of stars and swirling masses of gas and dust bound together in different shapes, galaxies are truly majestic objects in the sky. Contained in their hearts or nuclei are perhaps the most powerful engines in the universe. In some galaxies, the central nucleus out-shines the whole surrounding galaxy. Such galaxies are known as Seyfert or active galaxies. The knowledge gained from the studies of recent images, spectra and rapid variations in the light output (X-ray, optical, etc.) from the nuclei of galaxies has led to the current paradigm for the nuclear regions of different classes of active galaxies. Briefly describes the current observational knowledge about different types of galaxies, focusing on the activity emanating from the nuclear regions or the hearts of the galaxies.

30 ref

000039   Rastogi R G;James M E (Department of Physics and Space Sciences, Gujarat University, Ahmedabad-380 009) : Geomagnetic field variations at the equatorial electrojet observatory, Etaiyapuram. Indian J Radio Space Phys 2001, 30(5), 221-32.

Extent of the effect of electromagnetic induction in sub-surface has been investigated using geomagnetic data for the period 1980-1986 from a station Etaiyapuram situated between Trivandrum and Kodaikanal and away from the sea-coast, but close to the magnetic equator. The station Etaiyapuram exhibits forenoon maximum and afternoon minimum in Z component for all seasons, similar to that for Trivandrum, contrary to the expectations from Chapman's theory of equatorial electrojet. Daily variation of Z shows characteristic features for Trivandrum during the years when sun is active, but characteristic features for Kodaikanal when sun is calm suggesting that the latitudinal extent of anomalous induction in Palk Strait decrease with decreasing solar activity. The daily variation of disturbance in geomagnetic Z field does not indicate any abnormal effect due to induction, but storm time Dst(Z) variation shows clearly the induction effects. Similarly, the amplitude of storm sudden commencement (SSC) in ΔZ at Etaiyapuram is found to be affected byelectrojet as well as by the sub-surface currents.

000038   Ghosh S;Bandyopadhyay T K;Pant C;Sen D K; Rajawat R S (NO, , 15 & B Kyd St, Calcutta-700 016) : Devri-Khera: a new L6 chondrite. Meteoritics 2001, 36(9S), A241-5.

Devri-Khera meteorite fell on 1994 October 30 in the Jhalwar district of Rajasthan, northwestern India. The texture, mineralogy and mineral and bulk compositions show that Devri-Khera is an L6 chondrite of shock facies S4.

9 ref

000037   Chakrabarti S K;Nandi A (S N Bose National Centre for Basic Sciences, , JD Block, Salt Lake, Sector-III, Calcutta-700 098) : Fundamental states of accretion/jet configuration and the black hole candidate GRS1915+105. Indian J Phys-Pt B 2000, 75(1), 1-4.

Advective disk paradign of black hole accretion includes self-consistent formation of shocks and outflows from post-shock region. Applies this paradign to understand rich variation of the light curve of the black hole candidate GRS1915+105. Author propose that out of five possible fundamental states the black hole candidate GRS1915+105 moves around among three of them creating all possible observed light curves.

17 ref

000036   Bose S K;Bhattacharya A B (Department of Physics, Kalyani University, Kalyani-741 235) : Local time dependence of decametric radio emission from Jupiter observed from earth stations at different solar activity. Indian J Radio Space Phys 2001, 30(5), 233-42.

Investigates the local time dependence of decametric radio emission from Jupiter observed from earth stations and examines the phenomenon at different solar activity conditions. The results exhibit that, at different solar activity periods, all non-Io sources show high occurrence probability of decametric radio emission corresponding to high polar coronal hole size, and at the time of crossing of interplanetary magnetic field sector boundary to the Jovian magnetosphere, occurrence probability shows high intensity. The results have been critically interpreted by considering the interaction of solar wind with the Jovian magnetosphere.