021738   Kameswara Rao N;Sriram S;Gabriel F; Raghavendra Prasad B;Samson J P A;Jayakumar K;Srinivasan R;Mahesh P K;Giridhar S (Indian Institute of Astrophysics, , Bangalore-560 034) : Fiber-fed echelle spectrometer of the 2.34 meter vainu bappu telescope. Asian J Phys 2004, 13(3-4), 267-76.

The optical design and performance of high resolution fiber-fed echelle spectrometer for the 2.34 meter Vainu Bappu Telescope (VBT) is described. An optical fiber of core 100 μm and length 45 meter is used to link the spectrometer with the telescope. The instrument provides a resolving power of 72,000 (4 Km/s) with a 60 μm slit and provides continuous coverage with gaps for λ <60> 1 μm. The spectrum is recorded on a thinned back-illuminated Marconi 2048 x 4096, 15 μm square pixel, charge coupled device (CCD) detector. The wavelength coverage in a single order varies from roughly 35 Angsturm at X = 4050 Angsturm (range 4030Angsturm- 4065Angsturm) to 70 Angsturm (range 8465 Angsturm - 8535 Angsturm).The present overall efficiency of the spectrometer at 6000 Angstrum is about 10%. The operation of the spectrometer and object acquisition and guiding at the telescope end is described. Some of the observed spectra from VBT are also illustrated.

8 illus, 1 table, 3 ref

021737   Joshi V A (Physics Dep, Nawrosjee Wadia College, Pune 411 001) : Physics of musical instruments physics of the Tanpoora (Tambora). Phys Educ 2004, 21(2), 81-7.

Music itself is a science and therefore the musical instruments that produce it, are also based on scientific principles. In the article, all the aspects of the tanpoora are discussed and underlying scientific facts are given.

2 illus, 1 table, 8 ref

021736   Joshi V (Physics Dep, Nawrosjee Wadia College, Pune-411 001) : Physics of musical instruments, physics of sitar. Phys Educ 2004, 21(2), 143-8.

Among the stringed instruments used for playing melodies. Sitar is perhaps enjoys the most popular one in and outside India. Very intricately designed, the lute has its unique place in the world of music. All the aspects of the Sitar are discussed and the underlying scientific facts are given.

021735   Jagdev Singh;Sakurai T;Ichimoto K (Indian Institute of Astrophysics, , Bangalore-560 034) : Detection of cooler loop-tops in a coronal structure. Asian J Phys 2004, 13(3-4), 245-50.

Obtains off the limb spectroscopic observations covering a coronal region of 200" x 500" in [Fe x] 6374 Angsturm and [Fe xi] 7892 Angsturm emission lines simultaneously. Yohkoh soft X-ray images of the sun showed two independent coronal structures in the observed coronal region on the North-West limb. The structure at 20 ° N, overlying a sunspot group showed anincrease in FWHM of both the lines and increase in the intensity ratio of 7892-Angsturm to 6374Angsturm line with height above the limb, implying an increase in temperature with height in the coronal loops. Whereas the coronal structure at 32 ° N showed decrease in theFWHM of both the lines and also decrease in the intensity ratio with height. These variations with height imply that coronal loop-tops were cooler with respect to the foot points in the coronal structure at 32 μ during the observing period of about 11 hours. The reasonfor such a behaviour of this structure may be absence of an associated sunspot group, or the magnetic field configuration of the underlying region or coronal structure itself, or the beginning of formation of the structure or the decay phase of the structure.

3 illus, 13 ref

021734   Jadhao V G;Parida B K (NO, Regional Institute of Education, Bhopal-462 013) : The concept of force. Phys Educ 2004, 21(2), 99-111.

1 illus, 18 ref

021733   Gupte N;Ramaswamy R;Roy R (Physics Dep, Indian Institute of Technology, Chennai-600 036) : A perspective on nonlinear dynamics. Pramana J Phys 2005, 64(3), 307-13.

Presents a brief report on the conference, a summary of the proceedings, and a discussion on the field of nonlinear science studies and its current frontiers.

32 ref

021732   Gadkar V B;Saligram A D (Department of Physics, New Arts Commerce & Science College, Ahmednagar-411 001) : Development of a simple dip-coater for polymer waveguide fabrication. J Instrum Soc India 2005, 35(1), 122-7.

The Fabrication and Characterization of Polymer thin film integrated optical Waveguide is presented. The polymer films are deposited on microscopic- glass slides. The dip-coat techniques had been used in the fabrication process. Commonly used fabrication techniques are Spin-coating, Pyrolysis, Plasma deposition, Chemical vapor deposition etc. Developed a novel arid simple dip-coating technique. The coating machine has been fabricated in the laboratory using simple low power dc motor and simple pulley arrangements. The different pulling rate of the substrate from the solvent can be obtained with variation of the de voltage in a controlled manner. The Polymer thin films of several materials with different viscosity like PMMA, PC, Ps has deposited for various pulling rates. The variation of the film thickness with the concentration of the solvents has been reported. Optical absorption loss measurement is used for studying film thickness profile of the dip-coated samples. After deposition and curing process, characterization is done using mode excitation using prism couplings. Laser light (633 nm) was coupled in to the film using standard prism coupling techniques. The collected Raman emission is the measure of the guiding properties for the polymer films.

5 illus, 4 ref

021731   Datta S (NO, , 656, "Snehalata", 13th Main, 4th State, T K Layout, Mysore-570 009, Email: somdatta@yahoo.com ) : Magnetism as a relativistic effect. Phys Educ 2004, 21(2), 129-41.

One of the consequences of the postulates of relativity is Lorentz transformation which also leads to the correct rule for the force transformation as one switches from one inertial frame S to another one S' which is moving with velocity v with respect to the former. An immediate fallout is the transformation of a velocity-independent force into a velocity dependent force from one frame to another. This velocity dependent force has the form of the magnetic force as defined by the Lorentz force equation. It now follows that a statinary distribution of electric charges Q which exerts only electrostatic force qE on a test charge q with now exert, when moving, also a magnetic force qv x B on the same test charge.

3 illus, 12 ref

021730   Dana S K;Chakraborty S;Ananthakrishna G (Instrument Division, Indian Institute of Chemical Biology, Kolkata-700 032) : Homoclinic bifurcation in Chua's circuit. Pramana J Phys 2005, 64(3), 443-54.

Reports the experimental observations of the Shil'nikov-type homoclinic chaos in asymmetry-induced Chua's oscillator. The asymmetry plays a crucial role in the related homoclinic bifurcations. The asymmetry is introduced in the circuit by forcing a DC voltage. For a selected asymmetry, when a system parameter is controlled, and observed transition from large amplitude limit cycle to homoclinic chaos via a sequence of periodic mixed-mode oscillations interspread by chaotic states. Moreover observed two intermediate bursting regimes. Experimental evidences of homoclinic chaos are verified with PSPICE simulations.

12 illus, 23 ref

021729   Chattopadhyay R (NO, Haripal G D Institution, Khamarchandi-712 405, Hooghly) : Teaching physical concepts through experiment. Phys Educ 2004, 21(2), 89-92.

An experiment performed by class XII students which concerns the verification of the inverse - square law of magnetic force (Coulomb's law) using friction along an inclined plane is presented.

2 illus, 1 table

021728   Chandre C;Uzer T (Centre de Physique Theorique, , CNRS Luminy, Case 907, F-13288 Marseille Cedex 9, France, Email: turgay.uzer@physics.gatech.edu) : Instantaneous frequencies of a chaotic system. Pramana J Phys 2005, 64(3), 371-9.

The structure and geometry of high-dimensional, complex dynamical systems is usually hidden under a profusion of numerical data. Shows that time-frequency analysis allows one to analyze these data regardless of the number of degress of freedom. The method takes snapshots of the system in terms of its instantaneous frequencies defined as ridges of the time-frequence landscape. Using the wavelet transform of a single trajectory, it can characterize key dynamical properities like the extent of chaos, resonance transitions and trappings.

5 illus, 18 ref

021727   Bratu I;Veiga F;Fernandes C;Hernanz A (National R&D Institute of Isotopic and Molecular Technologies, , P O Box 700, R-3400 Cluj-Napoca 5, Romania) : FTIR spectroscopic investigation of tolbutamide/β-cyclodextrin and tolbutamide/hydroxypropyl-<98>-cyclodextrin inclusion complexes. Asian J Spectrosc 2004, 8(2), 55-62.

Based on a detailed analysis of FTIR spectra of inclusion complexes of tolbutamide with β-cyclodextrin and hydroxypropyl-β-cyclodextrin one can distinguish different mechanisms of complexation. The intermolecular hydrogen bonds between tolbutamide molecules are broken out in the case of tolbutamide/β-cyclodextrin system. The tolbutamide/hydroxypropyl-β-cyclodextrin inclusion complex presents a possible dissociation of the intermolecular hydrogen bonds in the tolbutamide crystal lattice replaced by weaker forces in the complexed materials. A complementary mechanism that can be identifed is based on the expelling of water molecules and consequently a change of the hydrogen bonding network during the complexation processes.

4 illus, 14 ref

021726   Bhanisana Devi R K;Nandakumar Sarma H; Arunachalam J;Sanjiv Kumar (Department of Physics, Manipur University, Canchipur, Imphal-795 003, Email: hnksarma@rediffmail.com) : Trace element analysis of some medicinal plants of Manipur using PIXE and PIGE techniques. Indian J Phys 2005, 79(4), 417-20.

Nineteen medicinal plants of Manipur have been investigated by Proton Induced X-ray Emission (PIXE) and by Proton Induced Gamma ray Emission (PIGE) techniques. Out of these, twelve medicinal plants were analysed by both PIXE and PIGE techniques. The elements K, Ca, Mn, Fe, Cu and Zn are present in varying concentrations (ppm level and above) in all samples analysed by PIXE. Ti, V, As, Se, Br, Cr and Ni are also present in many of the medicinal plants (below ppm level). The elements F, Na, Mg, Al and P are also detected in all medicinal plants analysed by PIGE technique. The concentrations of K, Ca, Mg and P are high in all samples; Mn, Fe, Cu, Zn, Na and Al are also present at much lesser quantities and F at least quantity.

2 illus, 1 table, 20 ref

021725   Bayrakceken F (Electronics Engineering Dep, Yeditepe Univ, Istanbul-34755, Turkey) : Spectroscopic study of an optical antenna. Asian J Spectrosc 2004, 8(2), 73-81.

M-xylene sensitized biacetyl fluorescence and phosphorescence has been investigated and photosensitized fluorescence and phosphorescence lifetimes of biacetyl in the vapor phase has been determined. Attempts to detect the triplet of biacetyl by its absorption spectrum were unsuccesful, due to primarily, it is believed, to the low extinction coefficients of the triplet, and the low triplet concentrations produced by the optical pumping device at room temperature.

6 illus, 2 tables, 25 ref

021724   Balaraman G S;Ananthkrishnan N (School of Physics, Georgia Inst of Technol, , Atlanta GA 30332-0430, USA, Email: gtg112n@mail.gatech.edu) : Synchronization a heuristic approach. Resonance 2005, 10(5), 15-25.

The article introduces the concept of synchronization with the help of simple examples of oscillators.

4 illus

021723   Ananthakrishna G (Materials Research Centre and Centre for Condensed Matter Theory, Indian Institute of Science, Bangalore-560 012, Email: garani@mrc.iisc.ernet.in) : On the dynamical mechanism of cross-over from chaotic to turbulent states. Pramana J Phys 2005, 64(3), 343-52.

The Portevin-Le Chatelier effect is one of the few examples of organization of defects. Here the spatio-temporal dynamics emerges from the cooperative behavior of the constituent defects, namely dislocations and point defects. Recent dynamical approach to the study of experimental time series reports an intriguing cross-over phenomenon from a low dimensional chaotic to an infinite dimensional scale invariant power-law regime of stress drops in experiments on CuAl single crystals and AlMg polycrystals, as a function of strain rate. Shows that an extension of a dynamical model due to Ananthakrishna and coworkers for the Portevin-Le Chatelier effect reproduces this cross-over. At low and medium strain rates, the model shows chaos with the structure of the attractor resembling the reconstructed experimental attractor. At high strain rates, the model exhibits a power-law statistics for the magnitudes and durations of the stress drops as in experiments Concomitantly, the largest Lyapunov exponent is zero. In this regime, there is a finite density of null exponents which itself follows a power law. This feature is similar to the Lyapunov spectrum of a shell model for turbulence. The marginal nature of this state is visualized through slow manifold approach.

6 illus, 25 ref

021722   Anandarao B G;Nandakumar M S (NO, Physical Research Laboratory, Ahmedabad-380 009) : A near-infrared spectroscopic and photometric investigation of a sample of young stellar objects. Asian J Phys 2004, 13(3-4), 193-204.

Presents an infrared spectroscopic and photometric investigation to understand the nature of a sample of eight well-known Young Stellar Objects with Keplerian disks. Presents K band spectra(2.1-2.4 μm) from Mt. Abu observatory and archival photometric data in the near-infrared and far-infrared regions. The spectra are in agreement with the interpretation of veiling by continuum emission by dust enshrouding the objects. In the case of FS Tau that shows molecular hydrogen emission line at 2.121 μm, suggests the possibility of an infrared companion. DG Tau shows evidence for yet another phase of disk emission variation; while the CO overtone bands observed in emission in GM Aur indicate their origin in an optically thick accretion disk. The spectral energy distributions of the objects from infrared photometry show flat distribution, indicative of Class II pre-main sequence phase for most of the sample objects. SED model fits suggest inner disk temperatures of 1100-2000 K, except in GM Aur that shows a much colder disk. The J,H,K color-color plots indicate FS Tau is in an earlier evolutionary stage than the others; while GM Aur appears to be closer to the Class III phase than the others.

3 illus, 2 tables, 53 ref

021721   Amritkar R E;Jalan S (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009, Email: amritkar@prl.ernet.in) : Synchronization of coupled chaotic dynamics on networks. Pramana J Phys 2005, 64(3), 455-64.

Reviews some recent work on the synchronization of coupled dynamical systems on a variety of networks. When nodes show synchronized behaviour, two interesting phenomena can be observed. First, there are some nodes of the flating type that show intermittent behaviour between getting attached to some clusters and evolving independently. Secondly, two different ways of cluster formation can be identified, namely self-organized clusters which have mostly intra-cluster couplings and driven clusters which have mostly inter-cluster couplings.

3 illus, 33 ref

021720   Almulhem A (Department of Physics, King Faisal University, P O Box 9149, Al-Ahssa, 31982, Saudi Arabia, Email: aalmulhem@kfu.edu.sa) : Charge fraction for positron auger neutralization of metal surface. Indian J Phys 2005, 79(4), 429-31.

The theory for Auger neutralization of positrons at metal surfaces was developed in an earlier work. Transition rate was calculated as a function of distance from surface. It was shown to decay exponentially with distance from surface. The charged fraction for positrons scattered in front of a metal surface and going through Auger neutralization is calculated in this work. The charge fraction for energetic positrons from aluminum surface is found to be very high, implying a low probability of neutralization for these energetic positrons. For positrons with velocity in the parallel direction less than 0.05 atomic units, the charge fraction almost diminishes.

1 illus, 23 ref

021719   Al Awfi S;Bowaaneh M;Elabbar A (Department of Physics, Taibah University, Madina Munwarah, Saudi Arabia, Email: alawfi99@hotmail.com) : Theoretical analysis of channeling atom through a mono-mode hallow optical fiber. Indian J Phys 2005, 79(4), 385-91.

Atom location, atom dipole polarisation and the order of excited mode are the principal factors governing the structure influences in a hollow optical fiber such as, enhancement or complete suppression of dipole emission rate in presence of the structure mode. In a hole diameter of the optical fiber of the order of 2-10 μm, only the fundamental mode with cut-off frequency 0.3 PHz can exist. This means that the system operates as an exact mono-mode optical fiber and the atom propagation maintains coherence. In the slow atom approach, the electric dipole moment vector is strained by the structure mode to ensure the electric field vector at the instantaneous position of the dipole. Therefore, the polarisation gradient of slow atom controls every effect emerging in the presence or absence of the structure mode. The influence of the slow atom approach is examined with reference to certain cases, involving sodium atoms in hollow mono-mode optical fiber. The role of the fundamental mode in the atomic motions is considered.

6 illus, 24 ref

021718   Acharya S;Mohanty G C (NO, , Friends Colony, Side of Dr G Roy House, P O Buxi Bazar, Cuttack-753 001, Email: swaroop_acharya 2000@yahoo.co.in) : Dipolar association in binary system - acetyl acetone (HAA) in carboxylic acids. Indian J Phys 2005, 79(4), 421-4.

Dielectric constant of binary mixtures of acetyl acetone (HAA) with butyric acid, propionic acid and acetic acid has been measured at temperature 303. 16 K and frequency 455 kHz. The data of dielectric constant has been utilised to evaluate mutual correlation factor, excess molar polarization and excess Gibbs free energy to elucidate the molecular interaction. The study reveals that interaction is maximum in butyric acid + HAA system and microheterogeneous β-clusters with antiparallel orientation of dissimilar molecules predominate in it.

3 illus, 1 table, 16 ref

020722   Zhang B;Zeng Q;Wen Q (College of Electronic Information, Sichuan Univ, Chengdu-610 064, PR China, Email: zhangbinff@sohu.com) : Propagation of flat-topped beams passing through a paraxial ABCD optical system with an without aperture. J Optics 2004, 33(1), 13-19.

Making use of the new model of flat-topped beams (FTBs) proposed by Li recently, the analytical expressions for the field distributions of FTBs passing through a paraxial ABCD optical system has been derived, were both unapertured and apertured cases have been considered. The lens system is taken as a typical example for the ABCD optical system. The closed-form expressions for the focused field distributions of FTBs are given. The focusing properties have been studied in detail.

4 illus, 19 ref

020721   Udupa D V;Shukla R P;Das N C;Mantravadi M V (Spectroscopy Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Theory of a holographic lens with a high efficiency. J Optics 2004, 33(2), 49-66.

Two element holographic lens is proposed for obtaining high efficiency in a holographic lens. The two element holographic lens is made up of an off-axis holographic lens and a plane holographic grating. The proposed holographic lens can be used for the correction of chromatic aberration in an achromatic doublet. The theory of the holographic lens and the V-value of the holographic lens are given. The formulae for longitudinal chromatic aberration, transverse chromatic aberration present in a simple holographic lens and a two element holographic lens are derived. It is observed that the expressions for longitudinal chromatic aberration is the same for both the conventional holographic lens and the two element holographic lens proposed. It is also observed that the expression for the transverse chromatic aberration is the same for both the conventional holographic lens and the two element holographic lens. The two element holographic lens may find application for designing large size achromatic doublet in combination with a glass lens for magnifying purpose.

14 illus, 11 ref

020720   Sudha G F;Palanivelu T G (Pondicherry Engineering College, , Pondicherry-605 014) : Imaging subsurface tissue using polarized light numerical results. J Optics 2004, 33(2), 67-79.

Tissue images obtained at deeper depths lack significant contrast. To enhance the contrast of these images and to increase the visibility of subsurface tissues, a method is proposed. This technique is based on the principle that photons at longer wavelengths penetrate deeper than photons at shorter wavelengths. In this technique, images in the original and orthogonal polarized states are recorded with the source illumination in linear polarized state in two different wavelengths. Image subtraction of a fraction of the copolarized image from the perpendicular polarized state is done on the images obtained at the two wavelengths. The images obtained after the first processing are subjected to the next image subtraction where the lower wavelength image is subtracted from the higher wavelength image. Monte Carlo simulations show that image has marked contrast upto 3 optical depths.

8 illus, 1 table, 15 ref

020719   Singh A K (Mathematics Dep, V.S.S.D. College, Kanpur-208 002) : Three dimensional free convection flow of a viscous fluid through porous medium with time dependent suction velocity. J Energy Heat Mass Transfer 2003, 25(4), 315-31.

Paper deals with study of three-dimensional unsteady free convection flow of an incompressible, viscous fluid past an infinite vertical porous plate subjected to a time dependentsuction velocity embedded with highly porous medium. The problem becomes three-dimensional due to variation of suction velocity in transverse direction to the plate. A series expansion method is used to solve the governing equations. Solutions for temperature field, main flow and cross flow velocity fields are obtained. The expressions for skin-friction and heat transfer are also obtained. The results obtained are discussed with the help of graphs and tables.

6 illus, 3 tables, 13 ref

020718   Shukla R P;Sanjiva Kumar;Sinha A K;Mallick M; Thakur S;Sahoo N K;Das N C (Spectroscopy Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : A simple method of calibration for multichannel spectrograph using charge coupled device (CCD) as a detector for Raman spectroscopy. J Optics 2004, 33(2), 87-107.

A wavelength calibration procedure has been devised for measuring the wavelength in the multichannel spectrograph using a single wavelength of radiation for calibration which can be obtained from commonly available lamps such as mercury spectral lamp, cadmium lamp, sodium lamp and thallium lamp. This wavelength calibration procedure has been incorporated in a multichannel Czerny-Turner type of spectrograph using CCD as a detector developed indigenously. The spectrograph uses a plane grating of frequency 1200 grooves/mm, concave spherical mirror of focal length 0.523 m as a collimating element and concave spherical mirror of focal length 0.5 m as a focusing element. The linear dispersion of the spectrograph varies from 2.519 pixel/Angsturm to 2.686 pixel /Angstrum. The spectrum is recorded on the CCD array of pixels 1024 x 256. The pixel size is 26 micron x 26 micron. The accuracy of wavelength measurement is found to be about 1 Angstrum. The instrument works in the wavelength region from 4000 Angstrum to 7000 Angstrum. Raman spectrum of benzene has been recorded by irradiating the sample with an intense beam of a diode-pumped green laser (λ = 532 nm) of power variable from 1 mW to 200 mW. The measured values of wavelengths of Raman lines of benzene using the multichannel spectrograph agree well with the values of the Raman lines reported in the literature. The multichannel spectrograph is found to be useful for Raman spectroscopic applications.

10 illus, 4 tables, 14 ref

020717   Shankar A;Tanwar L S;Sirohi R S (Precision Industrial Metrology Lab, NSIT, Sec-03, Dwarka, New Delhi) : A grating scale for noise free natural interference fringe suitable for compact displacement measuring grating interferometer. J Optics 2004, 33(2), 119-27.

A state of the art grating interferometer using the natural interference pattern from first order diffraction beams whose fringe periodicity changes half of the grating pitch whose movement or phase information gives the desired displacement measurement. In order to use such fringe it is essential to suppress zero and even order diffraction order beams which is done, generally by introducing a half wave path difference from two phase zones on each grating element zone in the binary phase grating with 50% fill factor. The presence of 3rd order beam restricts the placement of detector closer to the grating scale and so putting restriction on compactness of interferometer. A grating element groove structure is proposed which eliminates intensities in even 3rd and 6th order enabling placement of detector far closer to increase compactness of set-up.

4 illus, 2 tables, 15 ref

020716   Saminadan V;Meenakshi M (School of Electronics and Communication Engineering, Anna Univ, Chennai-25, Email: meena68@annauniv.edu) : Optimal wavelength converter placement in wavelength-routed optical networks by simulated annealing. J Optics 2004, 33(1), 1-11.

Wavelength-routed all-optical networks have emerged as a popular architectural solution for wide area networks and are being conceived for future broad-band communications. Call connection probability in such networks depend on the number of WDM wavelengths employed and on the capability for wavelength conversion at network nodes. Equipping all the network nodes with wavelength converters to reduce the blocking probability is not a cost effective solution due to the high cost of wavelength converters. Hence only some of the nodes are to be equipped with wavelength converters. The objective is to address the optimal placement of wavelength converters among the network nodes. "Placement" refers to providing a network node with wavelength conversion capability. The paper uses simulated annealing to determine Here the location of the converters in order to achieve minimum blocking probability. It is observed that this method significantly reduces the number of blocking probability calculations and has been applied to a six hop path and to the 14-nodes NSFNET. The results are verified with the published literature. This method achieves optimal and near-optimal solutions at low computational expense and minimum programming requirement.

5 illus, 1 table, 9 ref

020715   Nayak A K;Sawhney I K (NO, M/s SSP Limited (R&D Centre), 13 Mile Stone, Mathura Road, Faridabad-121 003) : Thermal conductivity of chhana measurement and correlations. Indian J Dairy Sci 2004, 57(4), 241-5.

Thermal conductivity of chhana at different temperatures and composition with regard to moisture, fat and protein content in chhana has been determined. Thermal conductivity of chhana varied from 0.331 to 0.442 w/m°C under the experimental range. It increased with increase in temperature, moisture and protein content in chhana. The effect of protein content on thermal conductivity of chhana was, however, not significant. An inverse correlation was observed between fat content and thermal conductivity. The experimental values of thermal conductivity of chhana at different compositions and temperatures of measurement were statistically analysed to develop prediction model for the thermal conductivity of chhana.

5 illus, 1 table, 14 ref

020714   Goswami A S;Ahmed G A;Choudhury A (Physics Dep, Tezpur Univ, Tezpur, Assam) : Super resolution and better contrast in second harmonic scanning optical microscope with low power laser beam. J Optics 2004, 33(1), 29-35.

Designing of a second harmonic scanning optical microscope has been reported. The presented results prove that even low power laser excitation beam can produce second harmonic image with super resolution and better contrast.

6 illus, 15 ref

020713   Chowdhury K R;Mukhopadhyay S (Physics & Technophysics Dep, Vidyasagar Univ, Midnapore-721 102, Email: r_kuladeep@rediffmail.com) : An all optical binary comparator using non-linear material. J Optics 2004, 33(2), 81-5.

Data comparison is an essential task in data processing systems. In the traditional electronic methods more than 100 GHz operational speed is not achievable at-all. This situation can be managed by introducing photon as information carrier where THz range of operational speed can be adopted easily. One bit all-optical binary comparison scheme is proposed. The scheme is developed by the proper use of optical non-linear material, acting as an optical switching device.

3 illus, 7 ref

020712   Chatterjee S;Hazra L N (Applied Physics Dep, Calcutta Univ, 92 A P C Road, Calcutta-700 009) : Optimum values for genetic operators in evolutionary optimization of structural design of cemented doublets. J Optics 2004, 33(2), 109-18.

Reports results of investigations on the effects of variation in values for genetic operators, namely, the crossover probability, the mutation probability and the threshold genetic diversity in acceptable populations, on evolutionary optimization of structural design of cemented doublets. It is observed that the convergence of the optimization run to the desired goals depends significantly on the choice of values for the genetic operators. Optimum values for avoiding undue stagnation and for enhancing speed of convergence are reported.

6 illus 1 table, 20 ref

020711   Chakraborty B (Research and Development Div, MECON Limited, Ranchi-834 002) : Color variation of polarized polychromatic beam passing through a birefringent medium. J Optics 2004, 33(1), 21-7.

When a polarized polychromatic beam passes through a birefringent medium, the constituent spectral components suffer different change in its state of polarization. As a result, when the beam passes through an analyzer, the color of the resultant beam changes depending on the orientation of the analyzer, state of polarization of the input beam, spectral intensity distribution of the source and the polarizing properties of the birefringent medium. Color variation of the resulting beam in CIELAB space is observed with the variation of the azimuthal angle of the analyser for both film-type chromatic and prism-type achromatic quarter wave retarder.

3 illus, 10 ref

020710   Anbarasan P M;Mohan S (Kanchi Mamunivar Centre for Post Graduate Studies, , Pondicherry-605 008, Email: anbarasanpm@rediffmail.com) : Theoretical and experimental study on coupling property of distributed-index microlenses in micro-optics. J Optics 2004, 33(1), 37-45.

An investigation on the performance of distributed-index microlenses as coupling elements has been analysed in terms of phase representation of ray tracing method for characterising mode distribution in micro-optical devices. The trajectory of rays in each microlens of the branching cricuit can be expressed in phase space derived from ray equations and the initial condition of the input rays. The coupling efficiency can be calculated as the ratio entering the collimating microlens as depicted with the associated configurations. The value of coupling efficiency for rod and planar microlenses have been determined from the respective phase space configurations due to the lateral offset of coupling elements. Computed coupling efficiency was in good agreement with the experimental ones.

7 illus, 1 table, 13 ref

019654   Vaidya R;Dave M;Patel S G;Jani A R (Physics Dep, Sardar Patel Univ, Vallabh Vidyanagar-388 120) : Growth and characterization of NbSe₂B> single crystals. Indian J Phys 2005, 79(1), 85-7.

Single crystals of niobium diselenide (NbSe₂) having a layered structure were grown by chemical vapour transport technique. (CVT) using iodine as transporting agent. The energy dispersive analysis by X-ray (EDAX) gives the confirmation about the stoichiometry of the grown single were a=3.49 ± 0.0.058 Angstrum and c=6.28± 0.058 Angstrum. The NbSe₂ single crystals possess hexagonal crystal structure. The X-ray density was found to be 6.2869gm/cm³ and volume was calculated about 66.24 (Angstrum)^{3. The resistivity measurements of the grown crystals wer e carried out within the temperature range of 300 K to 423 K. The crystals were found to exhibit semiconducting nature in this range. The behaviour of the resistance under pressure is thoroughly sudied using Bridgman anvil set upto 6.5 GPa. The resistance found decreasing as the pressure increases upto 6.5 GPa. The crystal shows semiconducting behaviour.}

2 illus, 4 tables, 26 ref

019653   Tiwari M;Singh V;Dhoble S J;Dubey R N (Physics Dep, Regional Institute of Education, Bhopal-462 013) : Thermoluminescence studies of CaS phosphors activated by Ce<. Indian J Phys 2005, 79(1), 65-8.

Thermoluminescence (TL) of Ce³⁺, Na⁺ and Ag⁺ activated CaS phosphors has been studied. The TL intensity decreases by the addition of monovalent activator (Na⁺) in CaS: Ce³⁺ phosphor. This may be due to the formation of Ce⁴⁺ ions during γ-irradiation, which do not participate in the TL process. Only one type of defect is formed in CaS due to its exposure to γ-radiation. Doping with Ce³⁺ or Ag⁺ ions in the CaS forms new defects, which are responsible for the additional TL peaks observed in these samples.

2 illus, 1 table, 12 ref

019652   Srivastava S K (NO, , 4525, Defence Colony, Jind-126 102, Email: sanjeevsrivastava1980@rediffmail.com) : Relationship between isothermal bulk modulus and volume expansion ratio for ionic solids. Indian J Phys 2005, 79(1), 47-50.

The different relationships between K_T and (V/V₀) for ionic solids viz. NaCl, KCl, MgO and CaO have been analyzed. The analysis is based on the experimental data reported by Anderson and extrapolated by Singh and Chauhan. It is found that the relationship 1n K_T = B(V/V₀) + constant, may be used to understand the thermoelastic behaviour of solids assuming that the isothermal bulk modulus varies linearly with temperature. The communication reveals that the Anderson Gruneisen parameter increases with temperature.

2 illus, 4 tables, 20 ref

019651   Singh V;Tiwari M (Physics Dep, Sadhu Vaswani College, Bairagarh, Bhopal-462 030) : Ce<. Indian J Phys 2005, 79(1), 51-3.

Sulphide based phosphors activated with Ce and Tb ions, were prepared by solid state diffusion method. Emission and excitation spectra were recorded at room temperature for CaS:Ce, CaS:Tb and CaS:Tb, Ce phosphors with the aim of studying their photoluminescence characterization as well as the energy transfer process. Photoluminescence study of phosphors shows the energy transfer from Tb³⁺ to Ce³⁺.

2 illus, 19 ref

019650   Salehi H (Physics Dep, Shahid Chamran Univ, Ahvaz, Iran, Email: salehi_h@cua.ac.ir) : Ab initio studies on band structure of CaTiO₃. Indian J Phys 2005, 79(1), 25-9.

The electronic structure, energy band structure, total density of states (DOS) and electronic density in cubic crystal CaTiO₃ are studied using WIEN2k package. This employs the full potential - linearized augmented plan wave (FP - LAPW) method in the framework of the density functional theory (DFT) with the generalized gradient approximation (GGA). The results show an direct band gap of 2.6eV at the Γ point in the Brillouin zone. The calculated band structure and density of states of CaTiO₃ agree with the previous experimental and theoretical results, as do the charge distribution and the prediction of the nature of the chemical bonding. Like other perovskite ABO₃, ferroelectrics, there is a hybridization between Ti 3d and O 2p, which is responsible for the tendency to ferroelectricity.

7 illus, 18 ref

019649   Safari R (Nuclar Physics Dep, Faculty of Physics, Tabriz Univ, Tabriz, Iran) : A local potential with analytical distorted wave approximation model for elastic scattering of pions from a nucleus. Indian J Phys 2005, 79(1), 89-92.

The ordinary equivalent local form of Kisslinger type optical potential together with an analytical distorted wave approximation (ADWA) is explained to discuss the elastic scattering of pions with intermediate energies from a nucleus. Calculation of angular distribution of the scattering of negative pion on ²⁰⁸₈₂Pb using Born approximation gives an acceptable fit to the data. The possible values for the potential parameters and ADWA parameters are obtained by comparison of data with the theoretical formula.

2 illus, 2 tables, 11 ref

019648   Ramachandran E;Natarajan S (Physics Dep, Thiruvalluvar College, Papanasam-627 425) : XRD, thermal and FTIR studies on gel-grown gypsum crystals. Indian J Phys 2005, 79(1), 77-80.

Gypsum is a very common inorganic mineral of wide industrial applications in the production of cement, ceramic, fertilizer, pottery, panels and plaster of Paris. Gypsum also occurs rarely as a bio-mineral. It crystallizes in the urine of humans due to acidic reaction. Hemihydrate of gypsum is found in statoliths. Gypsum is crystallized in silica gel under suitable pH conditions by reaction method. X-ray powder diffraction (XRD), thermogravimetric analysis (TGA/DTA), Fourier transform infrared spectrpscopy (FTIR) and density measurement studies of the gel grown gypsum crystals were made.

4 illus, 2 tables, 20 ref

019647   Rajnikant;Dinesh;Mousmi;Varghese B;Sharma B (Condensed Matter Physics Group, Jammu Univ, Jammu Tawi-180 006, Email: rkantverma@rediffmail.com) : X-ray structural analysis of 1H, 4H-terahydroquinolizino-(9, 9a,1gh) coumarin. Indian J Phys 2005, 79(1), 73-5.

The crystal structure of 1 H,4H-terahydroquinolizino-(9, 9a, 1gh) coumarin (C₁₅ H₁₅ NO₂) has been determined by X-ray crystallographic techniques. The compound crystallizes in monoclinic space group P2₁/n with a - 8.115(3), b = 19.067(10), c = 8.383(6) Angstrum, β = 115.45(15)° Z = 4. The structure has been solved by direct methods and refined to reliability index of 5.9%. The fused benzene and pyrone rings are planar. The piperidine ring C of the molecule adopts a distorted sofa conformation whereas the piperidine ring D exists in distorted chair conformation. The crystal structure is stabilized by intermolecular C-H...O hydrogen bonds.

3 illus, 3 tables, 17 ref

019646   Rajkhowa R;Sarma J K (Physics Dep, Tezpur Univ, Napaam, Tezpur-784 028) : Particular solution of DGLAP evolution equation in next-to leading order and x-distributions of deuteron structure functions at low-x. Indian J Phys 2005, 79(1), 55-64.

Author present particular solutions of singlet and non-singlet Dokshitzer Gribov Lipatov Altarelli Parisi (DGLAP) evolution equations in next-to-leading order (NLO) at low-x . Author obtain x-evolutions of deuteron structure functions at low-x from DGLAP evolution equations. The results of x-evolutions are compared with NMC low-x and low-Q² data and with those of leading order (LO) solutions of DGLAP evolution equations.

6 illus, 23 ref

019645   Mahesh M J;Gopalakrishna G S;Ashamanjari K G; Shashidhara Prasad J (Studies in Geology Dep, Mysore Univ, Mysore-570 006) : Hydrothermal synthesis and characterization of cobalt (III) hydrated pyrophosphate crystals: 2(CoHP₂O₇. Indian J Phys 2005, 79(1), 37-40.

2(CoHP₂ O₇) crystals were synthesized by hydrothermal technique in the form of single crystals and characterized by DTA, FTIR and X- ray diffraction method. 2(CoHP₂ O₇) crystals crystallized in monoclinic systems with cell parameter of a = 9.1609, b = 12.6764,c= 9.6868 A, <97> = γ = 90°, β = 106.7705 °, v = 1077.06 (15) Angstrum³ with space group P2₁/C₁ and paramagnetic nature. Solubility studies indicate that this compound shows positive coefficient of solubility.

7 illus, 13 ref

019644   Mahendran M (Physics Dep, Thiagarajar College of Engineering, Madurai-625 015, Email: mmahend@rediffmail.com) : Frustrated magnetic moments in small metal clusters. Indian J Phys 2005, 79(1), 69-71.

The magnetic properties of small antiferromagnetic clusters with nearest neighbour interaction containing atoms upto 561 have been studied. The magnetic moments of small antiferromagnetic clusters have been investigated as a function of size, temperature and magnetic field. The calculations for icosahedral and cuboctahedral clusters have been carried out self-consistently by assuming that the clusters undergo super paramagnetic relaxation. The effective magnetic moment (μ_eff) per atom of icosahedral clusters increases with magnetic field but decreases with increasing temperature. It is observed that μ_eff of icosahedral clusters reaches saturation value with magnetic field while that of cuboctahedral clusters remains unchanged with the magnetic field for N = 13 and 55 atoms in a cluster. It has been analyzed in both icosahedral and cuboctahedral clusters that μ_eff increases linearly with cluster size before saturating at larger size.

9 illlus, 4 ref

019643   Karan S;Sen Gupta S P (Materials Science Dep, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032) : Observations of dislocation behaviour of different crystallographic faces of solution-grown sodium sulphate single crystals by chemical etching. Indian J Phys 2005, 79(1), 11-17.

Solution-grown anhydrous Sodium Sulphate (SS) single crystals with chemical formula Na₂SO₄ are analyzed by X-ray powder diffraction and chemical etch techniques. X-ray diffraction reveals the lattice structure belonging to orthorhombic system with lattice parameter values, in good agreement with the reported ones. Optical microscopic observations of dislocation behaviour in several crystallographic faces namely {011), (111), {101} and {010} of SS by chemical etch technique are reported with greater details. The main features observed are the pyramidal pits, square pits, octagonal pits, low angle tilt boundary, extended rows of triangular pits, liquid inclusions, edge and screw dislocations etc. It is found that solvents in presence of an additive, form well-defined dislocation pits. The results are briefly analyzed from Cabrera's thermodynamic theory. In very few cases, Scanning Electron Microscopy shows a good correspondence between dislocation characteristics and observed etch pattern.

5 illus, 1 table, 33 ref

019642   Jha A;Shen S;Huang L H;Joshi P (The Institute for Materials Research, Leeds Univ, Houldsworth Buildings, Clarendon Road, Leeds, LS2 9JT, UK, Email: a.jha@leeds.ac.uk) : Spectroscopic properties of rare earth metal ion doped Tellurium oxide glasses and fibres. J Optics 2004, 33(3), 157-70.

The tellurium oxide (TeO₂) glasses are unique for their exceptionally large solubility for rare-earth metal ions. Paper discusses various structural thermal, and spectroscopic properties, essential for fibre and waveguide design. Low-loss fibre fabrication requires an understanding of a relationship between the glass structure, thermal properties, e.g the glass transition crystallisation, and melting temperatures, and the viscous relaxation. The properties of tellurium oxide glasses modified by the addition of sodium and zinc oxides, and their vibrational properties are characterised by Raman and infrared spectroscopy. The Raman spectra of these glasses show a range of structural units, namely TeO₃, TeO_3+δ, and TeO₄. The processes of tellurite glass preform and fibre fabrication are described in detail. The spectroscopic properties of rare-earth metal ion dopants (Er³⁺ , Tm³⁺, and Nd³⁺) are specially discussed for designing broadband fibre and waveguide amplifiers, covering nearly 400 nm wavelength for both coarse (C-) and dense (D-) wavelength division multiplexing (WDM) systems. The usefulness of such fibres in designing ultra-short fibre waveguide amplifiers, which are capable of yielding large gain, e.g. in Er³⁺-ion doped tellurite fibres larger than 30 dB internal (or relative) gain in the small-signal regime is possible in the C-band region.

6 illus, 3 tables, 39 ref

019641   Hasegawa A (Solitoncommunication, , Koto, Japan, Email: solitoncomm.com) : Application of optical solitons for information transfer in fibers. J Optics 2004, 33(3), 145-56.

Manuscript presents a tutorial review of application of optical solitons for information transfer in optical fibers. Starting with introducing of fundamental concept of dielectric response, dispersive and nonlinear effects in fibers, it derives the master equation, the nonlinear Schrodinger equation (NLSE) that describes information transfer in fibers and soliton solution. The dispersion managed soliton and Lagrangian approach for solving NLSE will also be presented as a practical application of soliton concept for ultra-high speed optical communications.

2 illus

019640   Harun S W;Ahmad H (Physics Dep, Malaya Univ, 50603 Kuala Lumpur, Malaysia, Email: wadi72@yahoo.com) : Effect of recycling a backward ASE of performance of double pass L-band EDFA. J Optics 2004, 33(3), 181-6.

A new double pass long wavelength band erbium-doped fibre amplifer (L-band EDFA) with a further improved gain is demonstrated using an un-pumped erbiumdoped fibre, (EDF) section. The wasted conventional band (C-band) backward amplified spontaneous emission (ASE) is used as a secondary pump source for the un-pumped EDF. A gain enhancement of 2 to 3.5 dB was observed without degradation in noise figure for the configuration where only the reverse propagated signal enters the un-pumped EDF. A high gain enhancement as high as 16 dB was observed especially at low pump powers for the configuration where the signal propagates twice through the un-pumped EDF. However, it degrades the noise figure severely.

4 illus, 5 ref

019639   Ghatak A (Physics Dep, Indian Institute of Technology, Delhi, New Delhi-110 016, Email: ajoykghatak@yahoo.com) : The optical fiber: A historical perspective. J Optics 2004, 33(3), 131-43.

An attempt has been mode to provide a historical perspective to the development of the field of fiber optics. Starting with Daniel Colladon's experiment demonstrating guidance of light within a water jet in the late nineteenth century, it traces various important milestones in the rise and rise of fiber optics that was witnessed in recent years to absorb the huge growth in bandwidth demand for Internet access and data transfer.

10 illus, 12 ref