Choudhury T R
019978 Choudhury T R (Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad-211 019, Email: wwwtirth.@hri.res.in) : Analytical models of the intergalactic medium and reionization. Curr Sci 2009, 97(6), 841-57.
Reionization is a process whereby hydrogen (and helium) in the Universe is ionized by the radiation from first luminous sources. Theoretically, the importance of the reionization lies in its close coupling with the formation of first cosmic structures and hence there is considerable effort in modelling the process. Gives a pedagogic overview of different analytical approaches used for modelling reionization. Also discuss different observations related to reionization and show how to use them for constraining the reionization history.
3 illus, 147 ref
Chengalur J N
019977 Chengalur J N (NCRA-TIFR, Pune Univ Campus, Ganeshkhind, Pune-411 003, Email: chengalur@ncra.tifr.res.in) : Low frequency observations of high redshift galaxies. Curr Sci 2009, 97(6), 793-803.
Although our understanding of the evolution of the stellar population of galaxies has improved dramatically in the recent past, ear understanding of the evolution of the neutral atomic gas content in star forming galaxies remains limited. This is largely because of the sensitivity limit of the current generation of radio telescopes. The scenario is changing however, both because of new instrumentation and deeper integrations with the existing telescopes. In this aticle, I review the current status of, and future prospects for, low radio frequency observations of gas in high redshift galaxies. The indications are that the community is moving from an era of fasting to an epoch of feasting.
13 illus, 85 ref
Chauhan P A;Kirankumar A S
019976 Chauhan P A;Kirankumar A S (Space Application Centre, Indian Space Research Organization, Ahmedabad-380 015, Email: prakash@sac.isro.gov.in) : Chandrayaan-1 captures halo around apollo-15 landing site using stereoscopic views from terrain mapping camera. Curr Sci 2009, 97(5), 630-1.
4 illus, 6 ref
Bhattacharyya S
019975 Bhattacharyya S (Astronomy and Astrophysics Dep, Tata Institute of Fundamental Research, Mumbai-400 005, Email: sudip@tifr.res.in) : X-ray views of neutron star low-mass X-ray binaries. Curr Sci 2009, 97(6), 804-20.
A neutron star low-mass X-ray binary is a binary stellar system with a neutron star and a low-mass companion star rotating around each other. In this system the neutron star accretes mass from the companion, and as this matter falls into the deep potential well of the neutron star, the gravitational potential energy is released primarily in the X-ray wavelengths. Such a source was first discovered in X-rays in 1962, and this discovery formally gave birth to 'X-ray astronomy'. In the subsequent decades, our knowledge of these sources has increased enormously by the observations with several X-ray space missions. Here we give a brief overview of our current understanding of the X-ray observational aspects of these systems.
13 illus, 117 ref
Bhattacharya D
019974 Bhattacharya D (NO, Inter-Univ Centre for Astronomy and Astrophysics, Pune-411 007, Email: dipankar@iucaa.ernet.in) : Frontiers in space astronomy. Curr Sci 2009, 97(6), 785-92.
This article reviews the baekground and the current frontier in space astronomy being done at various wavebands. Space-based platforms, free from the absorption and distortions introduced by the Earth's atmosphere, are able to provide both higher resolution and sensitivity over much of the electromagnetic spectrum, and have thus become necessary tools of a professional astronomer. This area of astronomy has seen a steady growth, which is expected to continue well into the future. The space astronomy activities in India are reviewed in this global context.
5 illus, 37 ref
Bharadwaj S
019973 Bharadwaj S (Physics and Meteorology Dep, Theoretical Studies Centre, Indian Institute of Technology Kharagpur-721 302, Email: somnath@phy.iitkgp.ernet.in) : Galaxy surveys. Curr Sci 2009, 97(6), 821-40.
Galaxy surveys provide us with a map of the local universe. They also contain detailed information about galaxy properties. Both these inputs, coming from galaxy surveys, have played a very important role in shaping our present picture of the universe. This article provides an introduction to galaxy surveys. Some of the large optical galaxy surveys carried out till date are described, and a few of the scientific findings of these surveys are highlighted.
17 illus, 4 tables, 112 ref
Raman V V
018674 Raman V V (Physics and Humanities at the, Rochester Institute of Technology, Rochester, New York, 14623, USA, Email: vvrsps@rit.edu) : Darshana jolts, the world above-1. Resonance 2010, 15(10), 954-64.
Darshana is a Sanskrit word which means seeing, knowing, worldview, and philosophy. It also refers to the vision one has of the Divine or of a representation of it. Darshana expresses how the human mind perceives the world of experience. In this series I will be using the term to refer to the revolutionarily new perceptions of the physical world that have arisen as a result of the science of the past four centuries. It is important to recognize these in the current context of India's intellectual history. Because of the unhappy intrusions of the British into India and her political sovereignty for over two centuries, along with the understandable historical rancor against the West, there has also arisen the mistaken notion that modern science is Western in its essence, and needs to be challenged by ancient Indian science. Fortunately, this is ignored by and large by the growing body of Indian scientists. Modern science emerged, evolved, and molded human civilization in unprecedented ways during the past four and odd centuries. By any fair, knowledgeable, and objective reckoning, the centuries from the seventeenth to the twentieth have been among the most significant ones in human history. Many people in the modern world do not realize the dramatic ways in which humanity's worldviews have been shaken and re-formulated. Those who have assimilated the newer worldviews are not always aware of when and how the extraordinary findings of modern science became part of humanity's collective consciousness. Much less is it realized how and when so much new knowledge came to our understanding in the course of these past few centuries. As a result, it is sometimes simplistically claimed that all the complex concepts and results of modern science were known to distant generations in ancient times. In this series I will be presenting some of the major jolts in our darshana of perceived reality that have occurred as a result of the rise of modern science. Philosophical criticisms of science to the effect that scientific knowledge is limited, that science cannot create life, etc., and apologists for ancient worldviews notwithstanding, the fact remains that even the social, political, and ethical bases of human civilization have been drastically transformed, for the good and in some cases for the bad, by the rise of science. (From now on, by science I will mean modern science.
Padmanabhan T
018673 Padmanabhan T (NO, IUCAA, Post Bag 4 Pune Univ Campus, Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in) : Dawn of science 5. the healing art. Resonance 2010, 15(10), 870-4.
It was in the field of surgery that ancient Indian medical practice achieved the most.
5 illus, 2 ref
Narlikar J V
018672 Narlikar J V (NO, Inter-University Centre for Astronomy and Astrophysics, Pune-411 007, Email: jvn@iucaa.ernet.in) : Fred hoyle's universe. Resonance 2010, 15(10), 875-904.
This article recalls some of the seminal contributions to astronomy made by Fred Hoyle. His ideas were thought to be unrealistic at the time they were proposed, but have now been assimilated into mainstream science. A general comment that emerges from such examples is that highly creative individuals who are far ahead of their times do not get the recognition they deserve once their ideas are rediscovered and accepted as standard: for, by the time this happens, they and their contributions are forgotten.
4 illus, 19 ref
Madhusudan H R
018671 Madhusudan H R (NO, J N Planetorium, High Grounds, Bangalore-560 001, Email: pallavimadhusudan@yahoo.co.in) : 1610: the year that improved our 'vision'. Resonance 2010, 15(10), 948-53.
The telescopic observations by Galileo Galilei in 1610 provided compelling evidence of a heliocentric system of the universe, as forwarded by Nicholas Copernicus in the earlier century. Firstly, Galileo established that the Earth was not the only centre of revolution. Therefore, the Earth did not enjoy a special place, as such. Next, his observations of Venus showed that the planet Earth clearly revolved around the Sun.
3 illus, 4 ref
Joseph T V
018670 Joseph T V (NO, Vikram Srabhai Space Centre, ISRO, Thiruvananthapuram-695 022) : Implementation of PLM system for launch vehicle project management. J Instn Engrs-Pt AS 2010, 91(May), 19-22.
A project management information solution is implemented for a new heavy lift launch vehicle project being developed by Indian-Space Research Organisation (ISRO). Launch vehicle project management involves continuous and goal oriented planning, supervision and real-time control of relevant project parameters and requires appropriate communication mechanisms. The objective of the new system is to enable the space organization to save time and project resources through organized creation, capture, updating, storage and access of data. The system is implemented in the areas of product data management, document management, change management, review systems and work break down structure development. The system is expected to deliver substantial gains to the organization by reducing the development cycle time and thus reducing costs.
7 illus, 4 ref
Kashyapi A;Shaha S K;Gulhane P M
003136 Kashyapi A;Shaha S K;Gulhane P M (NO, , Meteorological Office, Pune) : Impact of total solar eclipse on spectral radiance characteristics of various objects and comparision of different vegetation indices. Mausam 2003, 54(2), 483-94.
The division of Agricultural Meteorology, Pune of I.M.D. conducted a study of anomalous radiation environment during the last total solar eclipse period at Principal Evapotranspiration Observatory (PET) Canning, W.B. The spectral radiance characteristics from various objects viz. bare soil G.T.R. calibration plate (coated uniformly with BaSO4), rice crop at late vegetative state and rice crop at panicle (flowering) stage were measured from 23-25 October 1995 to in blue(0.45-0.52μ), red(0.62-0.68μ) and in the portion of near infrared (0.77-0.86μ) wavelengths, by use of multi-band ground truth radiometer(G.T.R.) and different vegetation indices were computed. The minimum values of spectral radiance were observed from all the four objects between 0830 to 0930 hrs IST on the eclipse day. The proportion of drop was the maximum in the portion of near infrared (NIR)band during the eclipse period for both the rice crop.The rice crop at late vegetative stage showed sharp drop in both RVI (ratio vegetation index) and NDVI (normalized difference vegetation index) values between 0830 to 0930 hrs IST, while the rice crop at panicle (flowering) stage showed sharp fall (in both the values) at 0830 hr IST both the RVI and NDVI values for the bare soil showed fluctuations on the eclipse day between 0730 to 1000 hrs IST. The MGVI (modified green vegetation index) values indicated that on the eclipse day during the period of total eclipse, quantity of radiation reflected by a different objects dropped in all the four bands.
6 illus, 10 ref
Javed S;Higuchi H;Nagendran M;Takekawa J T
003135 Javed S;Higuchi H;Nagendran M;Takekawa J T (Wildlife Sciences Dep, Aligarh Muslim University, Aligarh-202 002) : Satellite telemetry and wildlife studies in India: Advantages, options and challenges. Curr Sci 2003, 85(10), 1439-43.
Provides examples of three recent studies in India that have demonstrated and created a widespread appreciation of the use and benefits of satallite telemetry among biologists and managers. Also discusses the future prospects of this technology vis-a-vis benefits and challenges in the Indian subcontinent.
1 illus, 30 ref
Chattopadhyay R;Midya S K;De U K
002192 Chattopadhyay R;Midya S K;De U K (Haripal G.D. Institution, , Khamarchandi, Hooghly-712 405) : Statistical study on the temporal correlation of different solar parameters with OI 6300 Angstrom line intensity over calcutta and its implications. Indian J Radio Space Phys 2003, 32(3), 135-41.
The statistical analysis for the correlation between each of three solar parameters (i.e 10.7 cm solar flux, relative sunspot number and solar flare number) and the airglow OI 6300 Angstrom line intensity at Calcutta is presented. As strong correlations amongst the running averages of monthly mean values of all four parameters are found to exist, both in the descending and peak phases of the 21st solar cycle, empirical equations connecting annual running averages of the OI 6300 Angstrom line intensity with annual running averages of the various solar parameters have been found out. The variable parts of the parameters, which are defined as the original values (raw data) minus the running average value for a particular year, show their periodicity, particularly, in airglow OI 6300 Angstrom line intensity.
4 illus, 2 tables, 37 ref
Finvold R C
001191 Finvold R C (NO, , 4126 Quapaw Avenue, San Diego, California 92117, USA) : Planetary inertial power device. 0000, (NULL), (NULL).
Ramasamy A;Gurudath C S;Gupta P P; Narayanamurthy H
001190 Ramasamy A;Gurudath C S;Gupta P P; Narayanamurthy H (Thermal Systems Group, ISRO Satellite Centre, Bangalore-560 017) : Development of stirling cycle cryocooler for spacecraft applications. J Spacecraft Technol 2003, 13(2), 37-43.
To meet the requirement of cooling the detector of the payload to 80 K with 1W heat load, development work was initiated on a split type Stirling cycle cryocooler comprising a single compressor and a single stage expander. This unit was fabricated at ISRO Satellite Centre as per the design guidelines given by the Indian Institute of Technology, Bombay, Mumbai. Performance of this unit shows that it can provide cooling of one watt load at 80 K for a compressor input power of 33 W. To reduce vibration on the cryotip and the mounting platform, the development of dual opposed piston configuration was taken up and parametric studies are in progress. Preliminary performance test results show that this unit can provide one watt of cooling at 80 K for a compressor input power of 48 W.
6 illus, 2 tables, 4 ref
Ramana D V;Pal S;Shiva Prasad A P
001189 Ramana D V;Pal S;Shiva Prasad A P (Digital and Communication area, ISRO Satelite Centre, Bangalore-560 017) : New window functions suitable for high bit rate data transmission in space communications. J Spacecraft Technol 2003, 13(2), 33-6.
In recent years, the demand for transmission of large data through band-limited channels has been increasing rapidly. Since availability of spectrum is at premium, the need for bandwidth efficient modulation schemes has driven a great deal of research in this area. One such method for bandwidth efficiency is pulse shaping or windowing. By using a window function, one can reduce the power contained in the side lobes and concentrate on the signal near the carrier. Two new window functions have been suggested and studied. Comparisons with existing window functions such as rectangular, triangular are also carried out. Power and bandwidth are the major constraints for wireless applications, particularly in space communication. All the existing windows occupy more bandwidth, but the new suggested windown functions evolved have almost same rectangular window (reference window) function, as the main lobe width but with relatively side lobe levels.
4 illus, 8 ref
Nagaraj B P;Nataraju B S
001188 Nagaraj B P;Nataraju B S (Dynamics and Analysis Division, Spacecraft Mechanisms Group, ISRO Satellite Centre, Bangalore-560 017) : Energy transfer during locking of deployable flexible links. J Spacecraft Technol 2003, 13(2), 19-32.
Spacecraft appendages like solar arrays and antennae are lightweight and flexible. These are stowed during launch and deployed only in orbit. Development of these appendages is powered by pre-loaded torsion springs at joints which have locking mechanisms. The locking mechanism prevents further rotation of a joint when it reaches the predefined angle. During locking the system loses its rotational degree of freedom and, due to the inherent flexibility, vibration is induced in the system. The energy lost due to locking during the deployment of two-link and single-link appendages is estimated. The finite element method with Lagrange's equation is used for deriving the equations of motion, and the momentum balance method to obtain the state variables just after locking. Experiments have been carried out and results of both methematical modeling and experimentation are compared for joint rotation, strain and tip acceleration during motion. Energy transfer after each locking is discussed.
10 illus, 6 tables, 18 ref
Madhavan K N;Suryanarayana Rao K N;Usha V
001187 Madhavan K N;Suryanarayana Rao K N;Usha V (Communication Systems Group, ISRO Satellite Centre, Bangalore-560 017) : PSK demodulator for high bit rate telecommand system. J Spacecraft Technol 2003, 13(2), 13-8.
A high bit-rate telecommand PSK demodulator that is developed for use in the telecommand receivers of future ISRO satellites has been discussed. It essentially consists of two parts; a Costa's loop PSK demodulator and a PLL-based clock recovery circuit. The costas-loop design is based on analog components such as anlog multipliers, operational amplifers which are available in Hi-rel version. The sub-carrier is provided by either a VCO or VCXO. A PLL-based clock-recovery circuit for NRZ-l telecommand data format is part of the system. The design considerations, basic circuit implementation, a simple mathematical analysis, interfaces and performance evaluation of the system have been considered.
4 illus
Kane R P;Trivedi N B;Tanaka Y;Hajime Y;Pathan B M
001186 Kane R P;Trivedi N B;Tanaka Y;Hajime Y;Pathan B M (NO, Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, SP, Brazil) : Day-to-day variability of the equatorial electrojet strength. Indian J Radio Space Phys 2003, 32(5), 251-60.
The H ranges at the equatorial electrojet locations Ancon, Peru and Trivandrum, India, show substantial periodicities in the 2-20 day range which are absent in solar flux, and hence, should be attributed mainly to planetary wave activity and more so in quiet-sun intervals. However, the results for the two locations differ in details, indicating that these effects may not be global. The variations are seen mostly in the daytime values, indicating their association with the daytime electrojet strength only.
5 illus, 1 table, 34 ref
Dakshayani B P;Rao S V
001185 Dakshayani B P;Rao S V (Flight Dynamics Division, ISRO Satellite Centre, Bangalore-560 017) : Onboard ephemeris representation by a polynomial approach. J Spacecraft Technol 2003, 13(2), 7-12.
Increasing demand for onboard autonomy by present day ISRO missions motivated the development of onboard ephemeris computation by polynomial approach. An onboard emphemeris computation based on evaluation of truncated Fourier power series using the up linked Fourier coefficients with emphasis on reducing the uplinking load has been prsented. Each position component is represented by 23 coefficients, which amounts to 71 for the position vector with 200 m of root mean square error in position. Velocity components are derived from the position coefficients without going for one more set of coefficients, and thus further reducing the up linking load by half. This computational approach is implemented onboard TES (Technology Experiment Satellite). Analysis of the curve-fitting accuracy with the actual data shows that slightly larger error in position components on a few occasions is due to eccentricity variation, and phase shift between the actual and represented motions. This is tackled effectively by suitably shifting the epoch time. This approach of choosing the appropriate epoch does not have any impact on obboard operations and requires minor modifications in the ground software related to onboard ephemeris. This method is found to be well-suited for Indian remote sensing satellites.
5 illus, 7 ref
Annadurai M;Bhagavan H N
001184 Annadurai M;Bhagavan H N (ISRO Satellite Centre, , Bangalore-560 017) : Autonomous mode of spacecraft operations-GSAT-1 experience. J Spacecraft Technol 2003, 13(2), 1-6.
GSAT-1 was launched by first GSLV-D1 flight on 18th April 2001 from Satish Dhawan Space Centre, India, Short fall in the launcher-provided orbital velocity and spacecraft specific propulsion anomalies led to an orbit with a 23 hour period, with a drift rate of about 13° per day. To test and verify many of the new technological payloads, means of maintaining satellite health without RF contact for long durations of nearly two weeks between satellite visibility over GSAT-1 TTC station Hassan had to be devised. The problem was compounded with solar array drive assembly failure to track the sun. After detailed data analysis proper logics were devised and implemented by suitably updating onboard attitude and orbit control (AOCC) software. Proper power and thermal system configurations were arrived at. The autonomous mode of operations covered normal sun-lit period as well as special events such as lunar shadow and eclipse season. The Spacecraft functioned successfully for over a year to enable the verification of the new technology and survived two eclipse seasons.
3 illus, 3 tables, 3 ref
Perumal R V;Narayana Moorthi D;Vedachalam N; Madhavan Nair G
000105 Perumal R V;Narayana Moorthi D;Vedachalam N; Madhavan Nair G (Vikram Sarabhai Space Centre, , Thiruvananthapuram) : Second developmental flight of geosynchronous satellite launch vehicle. Curr Sci 2003, 85(5), 597-601.
The successful orbiting of GSAT-2 spacecraft in the intended Geosynchronous Transfer Orbit by the second developmental flight of Geosynchronous Satellite Launch Vehicle, GSLV-D2, on 8 May 2003 has marked the entry of GSLV into operational arena for 2000 kg-class spacecraft. The second flight of GSLV, in addition to validating the design of the vehicle, has also demonstrated the enhanced payload capability by an additional 300 kg over the first flight through certain improvements implemented. Further flights will gradually augment the payload capability to about 2500 kg.
^iia3 illus, 3 tables, 1 ref
Goswami M;Sucharita B;Arya P
000104 Goswami M;Sucharita B;Arya P (Integrated Test Range, , Balasore-756 025) : Performance evaluation of telemetry stations based on site selection. Def Sci J 2003, 53(3), 233-8.
In a test range, selection of sites for deployment of mobile telemetry stations plays a crucial role for acquiring and tracking any airborne vehicle under test. Efforts have been made to correlate the tracking performance of the auto track stations based on site selection for various test flights conducted from different launching pads. Some of the tracking methodologies discussed are single channel amplitude comparison monopulse (SCACMP) technique and E-SCAN technique. Also, the performance of a simple telemetry data acquisition system using helical antenna is compared with these auto track stations.
^ssc6 illus, 5 ref
Balachandra Rao S;Uma S K;Venugopal P
023833 Balachandra Rao S;Uma S K;Venugopal P (Bhavan's Gandhi Centre of Science and Human Values, , Bangalore) : Mean planetary positions according to Grahalaghavam. Indian J Hist Sci 0039, (NULL), 441-66.
The procedure for computations of the mean positions of the Sun, the Moon and the five planets (ta ra grahas) according the Grahalaghavam (GL) of Ganesa Daivajna is presented. The special features of GL in simplifying mathematical computations, finding the ahargana and determination of mean planetary positions are explained. Illustrative examples from the commentator Visvanatha are provided.
8 tables, 12 ref
Abhyankar K D
023832 Abhyankar K D (5-76, Vivekananda Nagar, Habshiguda St. No. 8/26, , Hyerabad 500 007) : Origin of the moving eccentric circle planetary model in India. Indian J Hist Sci 0039, (NULL), 429-39.
It is argued that the moving eccentric circle model of planetary motions might have been first put forward in India for explaining the planetary phenomena. Using the Rgvedic data about synodic periods of planets it is demonstrated how it gives rise to 7-tiered cosmos consisting of 7 regions (lokas).
3 illus, 4 tables, 9 ref
Verma P K;Dwivedi D K;Khanna K N
022822 Verma P K;Dwivedi D K;Khanna K N (Dep of Phys, V S S D Coll, Kanpur) : Extending Wertheim's perturbation theory to aperiodic solids. Indian J pure appl Phys 2005, 43(4), 265-9.
A theoretical study of two-dimensional hard homonuclear dumbbell-shaped aperiodic molecular system with a high anisotropy parameter d* = 0.924 employing Wertheim's first-order perturbation theory has been reported. The thermodynamic state of the aperiodic molecular solid known as DC-crystalline phase has been presented. The equation of state of two-dimensional dumbbell shaped molecules in fluid, HB and DC crystalline phases has been compared.
1 illus, 1 table, 23 ref
Sujatha S;Babu G S D;Ananthamurthy S
022821 Sujatha S;Babu G S D;Ananthamurthy S (NO, M P Birla Inst of Fundamental Res, Bangalore-560 001) : UBVRI CCD photometric studies of open cluster berkeley 15, Czernik 18 and NGC 2401. Bull Astr Soc India 2004, 32(4), 295-309.
CCD photometric observations of three open clusters Berkeley 15 (= OC1 414), Czernik 18 (= OC1 426) and NGC 2401 (= OC1 588), obtained for the first time in UBVRI filters down to V = 20 mag, are presented here. They are located at distances of 1259, 955 and 3467 parsecs with their respective ages estimated as
6 illus, 6 tables, 10 ref
Schmidt B P
022820 Schmidt B P (Res Sch of Astronomy and Astrophys, The Australian Natn Univ Mount Stromlo Obs, Cotter Road, Weston Creek, ACT 2611, Australia) : Measuring global curvature and cosmic acceleration with supernovae. Bull Astr Soc India 2004, 32(4), 269-81.
5 illus, 35 ref
Ravan S;Dixit A M;Mathur V B
022819 Ravan S;Dixit A M;Mathur V B (Cent for Dev of Advd Computing, , Pune University Campus, Pune-411 007, Email: arunmdixit@rediffmail.com) : Spatial analaysis for identification and evaluation of forested corridors between two protected areas in central India. Curr Sci 2005, 88(9), 1441-8.
Central Indian forested lands, biologically one of the most diverse regions in India, are facing the serious problem of habitat fragmentation both at small and large scales. While the entire conservation programme in this region revolves around a network of protected areas (PAs), safeguarding the genetic exchanges amongst wildlife populations, located in spatially separated but biologically rich PAs, is a prerequisite for the longevity of these conservation areas. Presents the results of a new methodological framework that evaluates the potential of forested tracts for functioning as viable corridoes between Kanha Tiger Reserve and Achanakmar Wildlife Sanctuary located in the states of Madhya Pradesh and Chhattisgarh respectively. Use 1:250,000 scale Indian remote sensing (IRS LISS-I) data to generate a detailed landuse map. The landscape suitability model is developed in GIS domain and is essentially based on two spatial characteristics of the landscape, viz. interspersion and juxtaposition, using landuse map. The landscape suitability model was refined by overlaying the human pressure map. The model underlines that a combination of moderate and highly suitable habitats can establish habitat connectivity between the two PAs. The model results are also substantiated by ground information collected from about 200 sample points across the forested landscape. Author also identified a few forest patches and various management strategies that are critical for the viability of the
3 illus, 4 tables, 34 ref
Ranade A;Gupta R;Ashok N M;Singh H P
022818 Ranade A;Gupta R;Ashok N M;Singh H P (NO, IUCAA, Post Bag 4, Ganeshkhind, Pune-411 007) : A near-infrared stellar spectral library: I. H-band spectra. Bull Astr Soc India 2004, 32(4), 311-33.
The paper presents the H band near-infrared (NIR) spectral library of 135 solar type stars covering spectral types O5-M3 and luminosity classes I-V as per MK classification. The observations were carried out with 1.2 meter Gurushikhar Infrared Telescope (GIRT), at Mt. Abu, India using a NICMOS3 HgCdTe 256 x 256 NIR array based spectrometer. The spectra have a moderate resolution of 1000 (about 16 A) at the H band and have been continuum shape corrected to their respective effective temperatures. This library and the remaining ones in J and K bands once released will serve as an important database for stellar population synthesis and other applications in conjunction with the newly formed large optical coude feed stellar spectral library of Valdes et al. (2004). The complete H-Band library is available online at: http://vo.iucaa.ernet.in/
9 illus, 6 tables, 19 ref
Qaiyum A
022817 Qaiyum A (Phys Dep, AMU, Aligarh-202 002) : Intensities of CII and CO lines and emissions from interstellar dust. Bull Astr Soc India 2004, 32(4), 283-94.
A comparative study of Weingartner and Draine (2001). (here-inafter referred as WD) and Bakes and Tielens (1994) (hereinafter referred as BT) models of photoelectric heating efficiencies of gas shows that for neutral medium WD model of photoelectric heating dominates over the BT model but in a medium where grains are positively charged BT is higher by many factors as compared to WD. WD model predicts a maximum photoelectric heating efficiency of the gas ε
6 illus, 1 table, 14 ref
Lata S;Mohan V;Sagar R
022816 Lata S;Mohan V;Sagar R (NO, Aryabhatta Res Inst of Observational Sci, Manora Peak, Naini Tal 263 129) : CCD photometry of the galactic star clusters Be 15, Be 71 and King 1. Bull Astr Soc India 2004, 32(4), 371-83.
Authors has present UBV RI CCD photometry of three open star clusters Be 15, Be 71 and King 1 for the first time. Base on these data, optical colour-magnitude diagrams (CMDs) for the stars in the clusters down to V = 22 mag are studied. There are 1408, 1887 and 2485 stars located in the regions of Be 15, Be 71 and King 1 respectively. Authors has also provide estimates of their fundamental parameters such as radius, reddening, distance and age. The radius values for the clusters Be 15, Be 71 and King 1 are 4.5, 3.0 and 4.0 arcmin respectively. The corresponding distances are 3.0±0.3, 3.9±0.4 and 1.9±0.2 kpc respectively while the ages are log (age)=8.5±0.1, 8.8±0.1 and 9.2±0.1 respectively. The red giant clump is clearly visible in the CMDs of cluster King 1.
6 illus, 6 tables, 17 ref
Green D A
022815 Green D A (Cavendish Laboratory, Mullard Radio Astronomy Obs, Madingley Road, Cambridge CB3 OHE, United Kingdom) : Galactic supernova remnants: an undated catalogue and some statistics. Bull Astr Soc India 2004, 32(4), 335-70.
A catalogue of 231 Galactic supernova remnants (SNRs) is presented, and the selection effects applicable to the identification of remnants at radio wavelengths are discussed. In addition to missing low surface brightness remnants, small angular size - i.e. young but distant - remnants are also missing from the current catalogue of Galactic SNRs. Several statistical properties of Galactic SNRs are discussed, including the surface-brightness/diameter (Σ-D) relation. It is concluded that the wide range of intrinsic properties of Galactic remnants with known distances, together with the observational selection effects, means that use of the Σ-D relation to derive diameters and hence distances for individual SNRs, or for statistical studies, is highly uncertain. The observed distribution of bright SNRs, which are thought to be largely free from selection effects, is also used to derive a simple model for the distribution of SNRs with Galactocentric radius.
14 illus, 3 tables, 121
Dwivedi B N;Mohan A
022814 Dwivedi B N;Mohan A (Appl Physic Dep, BHU, Varanasi-221 005) : The sun's mysteries from space. Resonance 2005, 10(1), 6-16.
5 illus
Das A K;Mukhopadhyay S
022813 Das A K;Mukhopadhyay S (Dep of Phys and Technophysics, Vidyasagar Univ, Midnapore(West)-721 102, Email: das_archan2@rediffmail.com) : All-optical system for wide range decimal multiplexing. Indian J pure appl Phys 2005, 43(4), 253-8.
In all optical parallel information processing, data computation and in optical communication, multiplexing and demultiplexing have a very strong role. Many multiplexing schemes in digital optical processing are already proposed. A new type of all-optical digital multiplexing system with only two triggering channels has been reported. Any input channel can be multiplexed here out of any number of such input channels with only those two triggering channels.
8 illus, 11 ref
Barai P;Krishna G;Osterman M A;Wiita P J
022812 Barai P;Krishna G;Osterman M A;Wiita P J (Dep of Phys & Astronomy, P O Box 4106 Georgia St Univ, Atlanta, CA 30302-4106, USA) : Expansion of radio galaxies in a cosmologically evolving medium: possible implications for the cosmic star-formation history. Bull Astr Soc India 2004, 32(4), 385-94.
Authors has compare earlier estimates of the volumes filled by lobes of radio galaxies during the quasar era based upon non-evolving ambient media with new ones assuming a strong cosmological evolution of the ambient medium. If the sources remain active for over 108 years the volumes filled by them are found to be comparable for the two scenarios. This strengthens our earlier inference that much of the cosmic web of gaseous filaments, the site of galaxy formation, was probably permeated by radio lobes during the quasar era and this could have triggered extensive star formation and made large contributions to the spread of magnetic fields and metals through the universe by z
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Thomas R M C;Gangadhara R T
021717 Thomas R M C;Gangadhara R T (Indian Institute of Astrophysics, , Bangalore-560 034, Email: mathew@iiap.res.in) : Influence of rotation on pulsar emission. Asian J Phys 2004, 13(3-4), 233-44.
Analyzes the motion of charged particles in rotating pulsar magnetosphere using the equation of motion, which was proposed earlier. Considers the projected magnetic field lines onto a 2Dplane perpendicular to the rotation axis, and derive the particle trajectory valid over a radial distance of about 10% of the light cylinder radius. The motive behind considering this model is to elucidate some of the effects of rotation on pulsar profiles. For example, the asymmetry in the observed pulse shapes can be explained by considering the aberration-retardation effects. The single sense circular polarization that has been observed in many pulsars, might be due to the relative orientation of sight line with respect to the plane of particle trajectory.
5 illus, 25 ref
Sundara Raman K;Ramesh K B;Selvendran R
021716 Sundara Raman K;Ramesh K B;Selvendran R (NO, Indian Institute of Astrophysics, Kodaikanal-624 103) : Evolution of the active region NOAA 10570 associated with the flares. Asian J Phys 2004, 13(3-4), 297-304.
The structure and evolution of the photospheric magnetic field observed in the active region NOAA 10570 are analyzed using Kodaikanal photoheliogram and spectroheliogram data. It is attempted to evaluate the shear angle changes by carefully observing the prominent umbrae belonging tothe active region. These changes in the orientation of the umbrae infer the rotational motion developed in the sunspot group. It is found that the flux and shear angle changes observed in the sunspot configurations are related to triggering of flares in the active region NOAA 10570.
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Srinivasa Rao M;Varghese B A
021715 Srinivasa Rao M;Varghese B A (Indian Institute of Astrophysics, , Bangalore-560 034) : Irradiation effects in close binary stars. Asian J Phys 2004, 13(3-4), 259-66.
Studies the reflection effect in 2-dimensional geometry to see how the field will change if we calculate the reflected radiation by the transfer equation in a close binary system. The reflected radiation is calculated from the extended surface of the components of a close binary system assuming 3-dimensional Cartesian coordinate geometry and circular orbits. The specific intensity of the radiation field is estimated along the line of sight for an observer at infinity. It appears that radiation field changes depending upon the position of the secondary component.
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Singh K P
021714 Singh K P (Astronomy and Astorphysics Dep, Tata Inst of Fundamental Res, Homi Bhabha Road, Mumbai-400 005, Email: singh@tiifr.res.in) : Techniques in X-ray astronomy. Resonance 2005, 10(6), 15-23.
X-ray astronomy has benefited enormously with the deployment of imaging X-ray telescopes in space, leading to a veritable revolution. Such telescopes require distortion free focusing of X-rays and the use of position sensitive X-ray detectors. In the article has described the importance of X-ray imaging, the optical principles behind the creastion of images and the instruments based on these principles. The various techniques used to fabricate such X-ray telescopes are described briefly.
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Saha S K;Yeswanth L
021713 Saha S K;Yeswanth L (Indian Institute of Astrophysics, , Koramangala, Bangalore-560 034, Email: sks@iiap.res.in) : Micro-fluctuations of fried's parameter (τo. Asian J Phys 2004, 13(3-4), 227-32.
The atmospheric coherence is a highly variable parameter depending upon the high velocity wind.The size of the atmospheric coherence length widely known as, Fried's parameter, τ0, has been computed during night at the Cassegrain focus of the 2.34 meter Vainu Bappu Telescope (VBT), Vainu Bappu Observatory (VBO), Kavalur, India, using the speckle interferometric technique. The variation of τ0 value at a different intervals during thenight is also computed. Measurements of τ0 at a step of
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Ramesh R;Kathiravan C;Satya Narayanan A
021712 Ramesh R;Kathiravan C;Satya Narayanan A (Centre for Research and Education in Science & Technology, Indian Institute of Astrophysics, Hosakote, Bangalore-562 114) : Seismology of the solar corona through observations of metric type IV radio burst emission. Asian J Phys 2004, 13(3-4), 277-84.
Presents metric radio observations of a transient, quasi-periodic type IV burst emission from the solar corona following the hard X-ray/H α flare of November 23, 2000. The radio event lasted for about 121 s, and the measured mean period was 14.7 ± 2.5 s.The source region of the observed radio emission was found to be located at a height of 0.18 ± 0.03 R. above the solar photosphere. The Alfven speed (νA) at that location was estimated to be 1185 ± 181 km s-1. Combinedwith the plasma density corresponding to the observing frequency (109 MHz), this gives a magnetic field (B) of 7.2 ± 1.1 G for the above region. We also estimated the speed of the disturbance propagating through the solar atmosphere in the aftermath of the flare, and is ≤ 755 km s-1.
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Namboodiri P M S
021711 Namboodiri P M S (NO, Indian Institute of Astrophysics, Bangalore-560 034, Email: pmsn@iiap.ernet.in) : Remnants of closely interacting galaxies. Asian J Phys 2004, 13(3-4), 215-26.
Merging and non-merging collisions of galaxies have been performed by numerical simulations. The galaxies are modelled as equal mass spherical systems and the density distribution closely follows the Plummer model. The simulations use a set values for the distance of closest approach in the range 0
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Anasooya Ashok;Satya Narayanan A;Ramesh R; Kathiravan C
021710 Anasooya Ashok;Satya Narayanan A;Ramesh R; Kathiravan C (Dep of Physics, Univ of Calicut, Calicut-673 635, ) : Global sausage and kink modes in coronal loops. Asian J Phys 2004, 13(3-4), 285-92.
MHD Oscillations and their presence in the solar corona is known both from theoretical predictions and observations such as TRACE (Transition Region And Coronal Explorer) and SOHO (Solar andHeliospheric Observatory). These modes have interesting consequences in coronal seismology, forexample in determining the strength of the magnetic field. Magnetic field structures (with strong gradients) are known to exist in the corona and they are often referred to as coronal loops.We model the loop to be made up of a cylindrical tube of constant cross-section. The magnetic field, pressure and density are assumed to be different both inside and outside the tube. The tube admits modes such as sausage (symmetric), kink (asymmetric), surface and body modes. The dispersion relation of the modes for a cylindrical tube which is compressible, infinitely conducting with uniform flows is presented. Limiting cases are discussed briefly. The phase speed of the kink mode is used as a diagnostic for determining the magnetic field of the corona. For different values of the coronal parameters, the magnetic field ranges from a few Gauss to 25 Gauss. The sausage mode does not exist for all wavenumbers. The condition for this mode to exist is todo with the ratio of the length of the loop to its diameter, which in turn depends on the density ratio. An example of quasi-periodic pulsations from radio observations found in the literature is presented.
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Zheng Y;Zhao Y;Dong F;Yao J;Hurle K
020709 Zheng Y;Zhao Y;Dong F;Yao J;Hurle K (NO, Institute of Plant Protection, Chinese Academy of Agricultural Scien, Beijing-100 094, China, Email: yqzheng62@sina.com) : Relationship of DIMBOA content in wheat seedlings and its resistance to plant pathogens. Allelopathy J 2005, 15(1), 137-44.
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Seshadri T R
020708 Seshadri T R (Phys and Astrophys Dep, Univ of Delhi, Delhi-110 007, Email: trs@physics.du.ac.in) : Fractal analysis of galaxy surveys. Bull Astr Soc India 2005, 33(1), 1-9.
Fractal analysis is a powerful tool to study the nature of galaxy distribution. The use of multifractal analysis of the galaxy distribution for the investigation of the transition to homogeneity in the Universe is reviewd. This analysis shows that the Universe is homogeneous over scales larger than about 80h-1 to 100h-1 Mpc.
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Saikia D J
020707 Saikia D J (NO, , ) : Discovery of a candidate microlensing event using the 104-cm Sampurnanand optical telescope at ARIES, Nainital. Bull Astr Soc India 2005, 33(1), 35-47.
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Kariyappa R;Satya Narayanan A;Dame L
020706 Kariyappa R;Satya Narayanan A;Dame L (NO, Indian Inst of Astrophys, Bangalore-560 034, Email: rkari@iiap.res.in) : Period-brightness relationship in chromospheric bright points. Bull Astr Soc India 2005, 33(1), 19-26.
Chromospheric bright points are sites where intense heating takes place by 3-min period waves. A 35-min-long time series of photographic spectra obtained in CaII H-line on a quiet region at the center of the solar disk under high spatial, spectral, and temporal resolution at the Vacuum Tower Telescope (VTT) of the Sacramento Peak Observatory has been analyzed to show that the period of intensity oscillations associated with bright points in the interior of the supergranular cells is independent of their intensity enhancements. Authors has found evidences for a constant period of oscillations in bright points, independent of their peak brightness, and different from the period of network oscillations. This suggests that the heating mechanism may be identical (by 3-min period waves) in any class of bright points while in the case of network elements it may be an entirely different mechanism (by 5-7 min period waves). In addition, it is shown that the amplitudes of the main and the follower pulses of bright points decay exponentially with time and the decay rate is constant with their brightness in any class of bright points.
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Das T K;Sarkar H;Manna A
020705 Das T K;Sarkar H;Manna A (NO, Cent for Space Phys, 43, Chalantika, Garia Station Road, Kolkata-700 084, Email: tukada2@vsnl.net) : Studies on Hα and SXR flares in relation to Type III metric bursts. Bull Astr Soc India 2005, 33(1), 11-18.
A study was made on H
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