001058   Khanna K M;Sakwa T W;Chelimo L S;Ayodo K Y (Physics Dep, Moi University, P.O Box 1125 Eldoret, Kenya) : Solid <. Indian J pure appl Phys 2008, 46(12), 857-61.

Under very high pressure, pockets of vacuum may be created around super solid ⁴He crystals. Crystals of ⁴He may flow through pockets of vacuum, one behind the other, and since the flow in vacuum will be frictionless and ⁴He atoms being bosons can swap positions, the flow may appear to be superfluid. Thus, the crystals will not be flowing into each other, but will flow one behind the other, and since they are identical, the flow may appear as superfluidity of solid ⁴He. The thermodynamic properties of the crystal, phase transition in solid ⁴He and supersolid ⁴He, zero-point energy and the size of the region in which the particle is confined under high external pressure, have been studied.

001057   Khamis I;Ghazi N (Nuclear Engineering Dep, Atomic Energy Commission, P.O. Box 6091-Damascus, Syria) : Calculation of power density distribution in miniature neutron source detector using the MTR_PC V2.6 code package. Indian J pure appl Phys 2008, 46(11), 755-60.

Spatial power distribution for the miniature neutron source detector (MNSR) has been calculated and presented as a function of the three coordinates. Accordingly, the MNSR Safety Analysis Report will be amended with the obtained information. The spatial power distribution has shown a maximum value for power density attained in the MNSR and reaches 3.24 w/cm³, located near the core center in case where the control rod is fully withdrawn. The effect of the control rod position on such power space-distribution in all 3-axis and various location of the control rod in the core were analyzed. Total, axial and radial peak power factors have been calculated. Their values were 1.27, 1.14 and 1.116, respectively. The Argentinean MTR_PC V2.6 code package was installed and utilized for various applications, especially, neutronics calculations for nuclear research reactors. Finally, the package was verified and utilized it through the calculations of both delayed neutron fraction and the prompt neutron generation time for the MNSR. The obtained values for these two parameters were 7.8673E-03 and 8.1534E-05 s, respectively. These parameters were calculated using the core calculation code CITVAP i.e. CITATION, having the microscopic cross-section library obtained by the code BORGES based on the cell calculation WIMS code. The presented results are in a very close agreement with the published results.

001056   Katoch A C;Sharma K K (Physics Dep, Shri Atmanand Jain College, Ambala City-134 002, Email: kks@nitham.ac.in) : CKM-favored and -suppressed and meson decays to a pseudoscalar and a tensor meson. Indian J pure appl Phys 2008, 46(10), 685-90.

The two-body and meson decays emitting a pseudoscalar and a tensor meson in the final state, using the factorization hypothesis have been investigated. Employs the Isgur, Scora, Grinstein and Wise quark model to evaluate the form-factors entering the decay amplitudes. Though many decay channels are available for B^- and B^-0 meson decays, the dominant ones are: B^- → Ds^-D_{2^*0, B^-0 → Ds^-D2^*+, B^- → π^-D^*02 and B^-0 →π^-D2^*+ which have the branching ratios (%) of the order of 10^-2. To the next order dominant decays are B^- → D⁰a2^-, B^-0 → D⁰}a_2⁰/D⁰f₂, B^- → η_CK₂^*- and B^-0 → η_CK₂^-*0, B^- → K^-D₂^*0/D^-D₂^*2 and B^- → K^-D₂^*0/D^-D₂^*2 and B^-0 → K^-D₂^*+/D^-D₂^*+, which have branching ratios (%) of the order of 10^-3. Hopes that the calculated branching ratios are within the reach of current experiments.

001055   Joshi B C;Upreti D K;Dhondiyal C C;Khulbey B (Physics Dep, Kumaun University, S S J Campus, Almora (Uttarakhand), Email: dkupreti17@yahoo.co.in) : Energy transfer between optically excited Tb<. Indian J pure appl Phys 2008, 46(10), 702-5.

A study of energy transfer from optically active ions Tb³⁺ to Er³⁺ in zinc phosphate glass has been made. The evidence of non-radiative energy transfer has been noted from the decrease of Tb³⁺ emission with increasing Er³⁺ concentrations. Energy transfer mechanism is mainly found to be electric dipole-dipole in nature. Various parameters such as energy transfer probability, transfer efficiency and average donor-acceptor distances have been computed.

001054   Jafari A;Moghimi A (Physics Dep, IRIB College, Tehran (Iran)) : Selective pre-concentration and solid phase extraction of mercury(II) from natural water by alumina -loaded bis (2-hydroxylamino) glyoxime phases. Oriental J Chem 2007, 23(1), 129-36.

Alumina phase loaded with bis(2-hydroxyphenylamino) glyoxime were synthesized based on chemical binding and physical adsorption approaches. The stability of a chemically modified bis(2-hydroxyphenylamino) glyoxime especially in concentrated hydrochloric acid which was then used as a recycling and pre-concentration reagent for further uses of alumina immobilized bis(2-hydroxyphenylamino) glyoxime. The application of this alumina for sorption of a series of metal ions was performed by using different controlling factors such as the pH of metal ion solution and the equilibration shaking time by the static technique. This difference was interpreted on the basis of selectivity incorporated in these sulfur containing alumina phases. Hg(II) was found to exhibit the highest affinity towards extraction by these alumina phases. The pronounced selectivity was also confirmed from the determined distribution coefficient (Kd) of all the metal ions, showing the highest value reported for mercury(II) to occur by alumina immobilized bis(2-hydroxyphenylamino) glyoxime phase. The potential applications of alumina immobilized bis(2-hydroxyphenylamino) glyoxime phase for selective extraction of mercury(II) to occur from aqueous solution were successfully accomplished as well as pre- concentration of low concentration of Hg(II) (40 pg ml^-1) from natural tap water with a pre-concentration factor of 200 for Hg(II) off-line analysis by cold vapor atomic absorption analysis.

1 illus, 4 tables, 29 ref

001053   Ilango G;Arivazhagan M;Joseph Prince J; Balachandran V (Physics Dep, M A M College of Engineering, Tiruchirappalli-621 105) : FTIR and FT-Raman spectral investigation of 2-chloro-1,3-dibromo-5-fluorobenzene. Indian J pure appl Phys 2008, 46(10), 698-701.

Normal coordinate calculations of 2-chloro-1,3-dibromo-5-fluorobenzene have been carried out using Wilson's FG matrix mechanism on the basis of General Valence Force Field (GVFF) for both in-plane and out-of-plane vibrations. The potential energy constants obtained in this study are refined using numerical methods.

001052   Hayat S S;Choudhry M A;Ahmad S A;Akhter J I; Hussain A (Physics Dep, The Islamia University of Bahawalpur, Bahawalpur 63120, Pakistan, Email: sikandariub@yahoo.com) : Study of thermal properties of nickel using embedded-atom-method. Indian J pure appl Phys 2008, 46(11), 771-5.

Thermal properties of metals and alloys have been studied for a long due to their importance in the materials design. Molecular dynamics simulation technique is applied to investigate thermal properties of Ni. Semi-empirical potentials based on the Embedded Atom Method (EAM) have been employed to calculate lattice parameter, energy per atom, mean square displacements and radial distribution function. Thermal properties like specific heat, thermal coefficient of linear expansion and melting temperature are deduced from the calculated parameters. The results are found to compare well with the experimental results.

001051   Gunasekaran S;Natarajan R K;Kala A; Jagannathan R (PG and Research Department of Physics, Pachaiyappa's College, Chennai-600 030) : Dielectric studies of some rubber materials at microwave frequencies. Indian J pure appl Phys 2008, 46(10), 733-7.

Studies on dielectric property of natural rubber (NR) and some synthetic rubbers viz., styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM), ethyl vinyl acetate rubber (EVA), PVC nitrile, butyl rubber, silicon rubber, neoprene, chlorosulphonated monomer, polyacrylic, fluorocarbon rubber, reclaimed rubber and polyblends of natural rubber with NBR and EPDM were carried out using microwave test bench system at X-band and K-band microwave frequencies. Analysis of dielectric property is inevitable since they determine the end electrical applications, per se, insulation. Present work is aimed at the determination of dielectric constant by using the method proposed by Robert and Von-Hippel. A systematic analytical approach was adopted in evaluating the data generated on dielectric constants for a variety of rubber materials. Interesting results were obtained by comparing dielectric constant values. The effect of microwave frequency, namely 9.6 GHz and 26GHz, as well as chemical modification brought about by vulcanization and reinforcement on dielectric constant values was probed. It appears from the study that among all samples polyblend of NR with EPDM posses interesting dielectric behaviour making it unique.

001050   Gunasekaran S;Anita B (Spectrophysics Research Lab, Pachaiyappa's College, Chennai-600 030, Email: anitabharathan@yahoo.com) : Spectral investigation and normal coordinate analysis of piperazine. Indian J pure appl Phys 2008, 46(12), 833-8.

Piperazine is a secondary amine with the molecular formula C₄N₂H₁₂. A normal coordinate analysis (NCA) has been carried out on this molecule with a systematic set of symmetry coordinates following Wilson's F-G matrix method based on D_2h point group symmetry. The frequency assignments in the FTIR and FTR spectra have been presented. A reasonable set of potential constants evaluated for this molecule has been compared with those of related molecules and are in the characteristic range. The potential energy distribution has been evaluated using the vibrational spectral data. The potential energy distribution value obtained reflects the correctness of the assignment made.

001049   Elsaid M K;Al-Naafa M A;Zugail S A (Physics Dep, College of Sciences, University of Hail, P.O.Box 2440 , Hail,Hail, Saudi Arabia, Email: mkelsaid@uoh.edu.sa) : Ground state properties of two dimensional quantum-dot helium in magnetic field. Indian J pure appl Phys 2008, 46(12), 876-9.

The ground-state properties of two-dimensional quantum-dot helium have been studied. The shifted 1/N expansion method has been used to solve the relative part Hamiltonian of two electrons confined in a quantum in the presence of an applied uniform magnetic field. The spin singlet-triplet transition in the ground state of the QD-helium is also shown. Based on comparisons, the eigen energies obtained by the shifted method are in excellent agreement with both exact and variational methods.

001048   Dhoble S J;Bramhe G V;Sonkawade R G;Moharil S V (NO, Kamla Nehru College, Sakkardara Square, Nagpur-440 009) : Phosphors MMgAl₁₀O₁₇: Eu,Dy (M=Ba,Sr,Ca) irradiated by Cs<. Indian J pure appl Phys 2008, 46(10), 695-7.

The thermoluminescence (TL) of Eu, Dy activated M MgAl₁₀O₁₇[M=Ba,Sr,Ca] phosphors has been reported. These phosphors are prepared by combustion synthesis. TL glow intensity of these phosphors is higher as compared to conventional CaSO₄:Dy TL-phosphor. M MgAl₁₀O₁₇[M=Ba,Sr,Ca] phosphors may be the possible candidate for thermoluminescence dosimetry of ionizing radiations.

001047   Chowdhury M P;Dalui S;Chakraborty B R; Mukherjee A;Pal A K (Instrumentation Science Dep, Jadavpur University, USIC Building, Calcuttta-700 032, , Email: msakp2002@yahoo.co.in) : Effect of carbon content on the mechanical properties of ternary boron-nitrogen-carbon compound. Indian J pure appl Phys 2008, 46(11), 776-82.

BNC films have been deposited on Si (100) and fused silica substrates by inductively coupled plasma chemical vapour deposition (ICP-CVD) technique using a mixture of borane-ammonia, nitrogen and methane as precursor gases. Carbon content in the films is varied by changing the concentration of methane in the precursor gases. The films are amorphous in nature. The films, thus, deposited have been characterized by using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction and Secondary Ion Mass Spectroscopy (SIMS). Microstructural information has been obtained from SEM studies. Microhardness has been seen to decrease with the increase in carbon content and the highest microhardness observed in these films has been found to be~5.3 GPa.

001046   Chopra D;Guru Row T N (Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560 012, Email: ssctng@sscu.ernet.in) : In situ cryocrystallization : pathways to study intermolecular interactions. J Indian Inst Sci 2007, 87(2), 167-211.

In situ crystallization of a liquid, the subsequent determination of its molecular and crystal structure and consequent study of intermolecular interactions is an area of contemporary interest. This technique has been successfully applied for the structure determination of compounds, which are liquids at room temperature, solvents, low-melting solids, gas hydrates and ionic liquids. Particularly in solvents, the importance of how the molecules pack in the crystal lattice is of relevance in the context of polymorphic modifications and their possible implications in directing other molecules to crystallize. In situ cryocrystallization, i.e. crystallization of compounds in capillaries on the diffractometer, has offered meaningful outputs to understand both intra- and inter-molecular interactions. These offer well defined targets for molecular design, which can be exploited for the design of futuristic materials including areas like drugs, Pharmaceuticals and technologically important materials.

85 illus, 1 table, 26 ref

001045   Beri V K;Nishchal N K;Gupta A K;Rastogi V K (Photonics Div, Instruments Research & Development Establishment, Dehradun, Email: nknishchal@iitg.ernet.in) : Design parameters of hybrid correlator. Indian J pure appl Phys 2008, 46(12), 844-51.

The design issues of a hybrid correlator are discussed. The architecture of the hybrid correlator is similar to the conventional 4-f correlator, with a difference that the first Fourier transformation, filter synthesis and their multiplication are done digitally using a digital signal-processing unit. The input to the correlator is the scene/target captured either through a CCD camera or thermal imager. Wavelet-modified maximum average correlation height filter is used for catering the need of in-plane rotation, out-of-plane rotation and scale invariant target recognition. The product function is displayed over a high-speed spatial light modulator, which when illuminated with a laser light results correlation outputs due to optical Fourier transformation. A chirp function is employed with the filters that helps to capture the desired autocorrelation peak discarding the dc and one of the undesired autocorrelation peaks. The space-bandwidth of the processor and focal length of the required lens are discussed. The requirement of zero padding of the product function is also discussed. Simulation and experimental results are presented.

001044   Badr Y;Battisha I K;Salah A;Salem M A (NO, National Institute of Laser Enhancement Sciences (NILES), Cairo Unive, Egypt, Email: szbasha@yahoo.com) : Up-conversion luminescence application in Er<. Indian J pure appl Phys 2008, 46(10), 706-11.

Sol-gel derived nano-crystalline titanium dioxide films doped with 1 up to 5% Er³⁺ ions were prepared by dip coating sol-gel method. The coating sol was obtained by hydrolysis of Ti(OC₄H₉)₄ in ethanol/HCl solution. The FT-Raman and the X-ray diffraction (XRD) were carried out to determine the crystal structure of the prepared samples. The morphology SEM and the cross - sectional of the film were used to characterize the microstructure and the thickness of the prepared film. It is shown that relative homogeneous, crack-free and transparent film was achieved via dipping process at 500°C.After the excitation with laser diode at wavelength 808 nm, visible (Vis) and infrared (IR) up-conversion emissions were evidenced in the thin film samples under investigation. The up-conversion was found to depend strongly on the Er³⁺ ion concentrations. The visible emission was found to be at 540, 560, 590 and 640 nm for thin film. They are attributed to intra-4f transition of Er³⁺ ions and assigned to the (²H_11/2 + ⁴S_3/2) and ⁴F_9/2, which are populated through excited state absorption (ESA) for 808 nm excitation.

001043   Azooz M A;Abou Aiad T H M;El Batal F H;El Tabii G (Glass Research Dep, National research Center, Dokki, Cairo, Egypt) : Characterization of bioactivity in transition metal doped-borosilicate glasses by infrared reflection and dielectric studies. Indian J pure appl Phys 2008, 46(12), 880-8.

Borosilicate glasses with the addition of one of the 3d-transition metals (TiaCu) (0.1 g/100g glass) have been investigated as possible materials having bioactivity by infrared reflection spectroscopy and electrical properties after the immersion in simulated body fluid (SPF) for different interval of times. The results show obvious effects of the transition metal ions on the bioactivity of the borosilicate glasses. The results are discussed taking into consideration recent achievements that govern the formation of hydroxyapatite surface layer on glass. Also, IR and electrical results are discussed in relation to the glass composition and structure, which confirm the effect of the formation of HAp layer and the possible mixed ionic and electronic mechanisms due to the addition of transition metal oxides.

001042   Arya B S;Aynyas M;Sanyal S P (Physics Dep, Govt. Narmada College, Hoshangabad-461 001, Email: aynyas@rediffmail.com) : High pressure study of structural and elastic properties of barium chalcogenides. Indian J pure appl Phys 2008, 46(10), 722-6.

The structural and elastic properties of barium chalcogenides (BaX; X = S, Se, Te) under high pressure have been investigated by using a two body inter-ionic potential approach with modified ionic charge (Zm^e). The equation of states in NaCl type to CsCl type structural phases for BaX has been depicted and found that the volume collapses at the phase transition pressures. The phase transition pressures 7.2 GPa, 6.1 GPa, 5.0 GPa respectively for BaS, BaSe, and BaTe obtained by us, are in close agreement with experimental data (6.5 GPa, 6.0±0.2 GPa, 4.8±0.3 GPa). The bulk modulus, pressure derivatives, second order elastic constants (SOEC) and third order elastic constants (TOEC) at high pressure have been calculated, which show predominantly ionic nature of these compounds. The variation of second order elastic constants (C₁₁, C₄₄) with pressure has been presented.

001041   Acharya B S;Nayak B B (NO, Regional Research Laboratory, Bhubaneswar-75101, Email: bsacharya @ gmail.com) : Microstructural studies of nanocrystalline thin films of V₂O₅-MoO₃ using X-ray diffraction, optical absorption and laser micro Raman spectroscopy. Indian J pure appl Phys 2008, 46(12), 866-75.

Compound thin and thick films of V₂O₅-MoO₃ system deposited on plane glass and conducting glass by electron beam and vacuum deposition have been studied by X-ray diffraction, optical absorption, high temperature in-situ X-ray diffraction and laser micro Raman spectroscopy. The films were also subjected to hydrogen insertion through plasma technique. The band gaps of these films were found to lie in the range 2.26-2.84 eV and the variation in the band gaps of these compound thin films does not follow a linear relationship with the composition. This non-linear variation of the band gap has been explained on the basis of pseudo potential approach advocated by Philips and bond order length strength (BOLS) effect in nano crystalline semiconducting thin films. The interference pattern obtained in the transmission spectra has been utilized to calculate the film thickness which agrees well with that of the value obtained by weight difference method. Laser micro Raman spectra were studied for the films. Several bands observed for these thin films have been explained on the basis of different bending, stretching and lattice phonon vibration modes occurring in the films.

000131   Yadav B S;Sharma R;Ali I (Molecular Spectroscopy and Biophysics Laboratory, D.N. College, Meerut-250 002) : Vibrational spectral study of 2-chloro-6-methoxy pyridine. Oriental J Chem 2007, 23(2), 747-50.

The FTIR and Laser Raman spectra of 2-chloro-6- methoxy pyridine have been recorded in the region 4000-400 cm^-1 and 4000-100 cm ¹ respectively. The bands observed in the FTIR spectra and Laser Raman spectra are discussed by assuming the compound under C_s point group symmetry. The probable assignments of the above molecule are based on group frequency approach together with the data available for similar molecules.

3 illus, 1 table, 12 ref

000130   Singh S;Rawat B S;Tayahi M B;Hanf M;Furth S; Gessner T (Electrical Engineering Dep, University of Nevada, Reno, NV 89557, USA, Email: rawat@ee.unr.edu) : Micro mirror based Hadamard transform spectrometer. Asian J Phys 2008, 17(2), 203-12.

Hadamard transform spectrometer (HTS) is realized using micro mirror array of 48 micro mirrors. These micro mirrors are fabricated using MOEMS technology. The array is actuated by applying digital signal based on the Hadamard matrices. Thus, the wavelength associated with the micro mirror is encoded using the Hadamard matrices. The spectrum results of the known filters are determined using the spectrometer and compared with the known results. Any discrepancy in the obtained results from the known results are discussed.

10 illus, 10 ref

000129   Singh J (Applied Research Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, Email: jxs46@psu.edu) : Novel nanomaterials synthesis by laser-liquid-solid interaction. Asian J Phys 2008, 17(2), 225-40.

A novel laser-liquid-solid interaction (LLSI) technique has been developed that is highly flexible and allows engineering nanomaterials in the form of particles, rods and tunes from liquid precursors. Synthesis reaction takes place in a molecular level, and the reaction rate is controlled by laser energy input, precursor solution chemistry and other processing parameters including interaction time, and thermal conductivity of solid that is spinning in the solution. By the proper selection of liquid precursor, mono-dispersed silver nanoparticles were produced with average particle size of 7-10 nm. Alloys of Ag and Ni were produced in the form of nanoparticles and nanotubes with an average diameter of 40 nm. HRTEM of nanorod exhibited that Ag acted as seed for the synthesis of immiscible of Ag-Ni alloy. Laser writing of silver exhibited 50% lower electrical resistivity, and eliminated many intermediate steps involved as compared to conventional silver patterning process.

14 illus, 4 tables, 24 ref

000128   Singh A K;Prabhu C M R (Faculty of Engineering and Technology, Multimedia University, Melaka, Malaysia, Email: c.m.prabu@unu.edu.my) : Design of low power SRAM cell for write/read operations. Asian J Phys 2008, 17(2), 273-8.

A new design approach for SRAM cell is proposed to reduce the power consumption/dissipation during write/read operation. Mainly used two tail transistors, one n-MOS and other p-MOS, in the respective inverter to avoid the charging or discharging of the respective nodes. The proposed circuit is simulated with the help of MICROWIND3 and DSCH 3 in advanced MOSIS technology for different size and power supplies. Our designed SRAM cell consumes approximately 50% less power than the conventional SRAM. Power dissipation is also found to be lower than the conventional SRAM. Most of the write operation is '0' and our circuit shows a better stability in the write '0' operation. In the read operations, power consumption is approximately the same as the conventional cell. The only drawback of our circuit is that it uses two extra transistors than the conventional one.

4 illus, 3 tables, 15 ref

000127   Rahman M;Choudhury P K (Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor, Malaysia, Email: pkchoudehury@yahoo.com) : Particle physics with extra dimensions: state-of-the-art. Asian J Phys 2008, 17(2), 263-72.

Extra dimensions (EDs), if they exist, have many implications in particle physics beyond the standard model (SM). They may solve the hierarchy problem without relying on supersymmetry or technicolor. The validity of string theory largely relies on the existence of EDs. Therefore, searches for EDs constitute a promising direction in particle physics. In the present article we review the state-of-the-art of the research in both theoretical and experimental arena.

41 ref

000126   Pathmanathan S S;Abdul-Rashid H A;Choudhury P K (Faculty of Engineering, Multimedia University, Cyberjaya-63100, Setangor,Malaysia, Email: pkchoudhury@yahoo.com) : An experimental investigation of double-pass erbium-doped optical amplifier with tunable band-pass filter. Asian J Phys 2008, 17(2), 241-4.

Presents an experimental investigation of the performance characteristics of a double pass erbium-doped fiber amplifier (DFA) with tunable band-pass filter (TBFs). The TBF is essentially used to suppress the undesired amplified spontaneous emission (ASE). Both co- and counter- 1480 nm pumpings are considered. Gain and noise figure of the EDFA are measured. The results show that the signal achieves a higher gain in the case of double-pass amplification with TBF. No significant improvement is achieved when co- and counter-pumpings are employed.

4 illus, 17 ref

000125   Misra D K (Electrical Engineering and Computer Science Dep, University of Wisconsin - Milwaukee, P.O. Box 784, Milwaukee, WE53201, USA, Email: misra@csd.uwm.edu) : A survey of the techniques for nondestructive electrical characterization of materials at microwave frequencies. Asian J Phys 2008, 17(2), 193-202.

Nondestructive methods for the electrical characterization of materials are desired in many industrial and scientific applications. It includes in-vivo characterization of biological mediums, in-situ measurements of various structures, and non-contact testing of disbands in composites. These methods are based on the measurement of reflection and/or transmission of electromagnetic signals interacting with the sample material. A radio frequency or microwave signal is applied to the material-under-test via a suitable sensor that is sometimes placed near the sample medium. The same sensor may be used to collect the echo signal carrying the characteristics of the sample material. Rectangular as well as circular aperture waveguides, coaxial lines, microstrip lines, coplanar waveguides, and dipole antennas have been employed for such measurements. These techniques require an electrical equivalent model of the sensor to extract the sample characteristics. Free-space methods have been used mostly at the millimeter waves and optical range where the signal beam incident on the sample is monitored to find the material properties. This paper reviews the current status of these techniques including a summary of recent admittance models of the sensor. Selected experimental and computational results are included along with the limitations of the technique.

5 illus, 2 tables, 70 ref

000124   Lakhtakia A;Polo J A (Engineering Science & Mechanics Dep, Pennsylvania State University, University Park, PA 16802, USA, Email: akhlesh@psu.edu) : Morphological influence on surface- wave propagation at the planar interface of a metal film and a columnar thin film. Asian J Phys 2008, 17(2), 185-91.

The selection of a higher vapor deposition angle when growing a columnar thin film (CTF) leads to surface-wave propagation at a planar metal-CTF interface with phase velocity of lower magnitude and shorter propagation range. Acordingly, a higher angle of plane-wave incidence is required to excite that surface wave in a modified Kretschmann configuration.

2 illus, 2 tables, 15 ref

000123   Joshi P S (NO, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005, Email: psj@tifr.res.in) : On the genericity of spacetime singularities. Pramana J Phys 2007, 69(1), 119-35.

Considers the genericity aspects of spacetime singularities that occur in cosmology and in gravitational collapse. The singularity theorems (that predict the occurrence of singularities in general relativity) allow the singularities of gravitational collapse to be either visible to external observers or covered by an event horizon of gravity. It is shown that the visible singularities that develop as final states of spherical collapse are generic. Some consequences of this fact are discussed.

27 ref

000122   Inderjit Singh;Kumar U;Kesari V;Jain P K;Basu B N (School of Electrical Sciences, Vellore Institute of Technology, Vellore, Email: pkjain_vns@hotmail.com) : Electromagnetic analysis of ohmic quality factor for the tapered gyrotron cavity. Asian J Phys 2008, 17(2), 289-96.

A simple electromagnetic method has been presented, by dividing the input- and output-taper sections of cavity into numbers of non-tapered circular steps, to calculate the ohmic quality factor of tapered cavity of a gyrotron. The energy stored in cavity and power loss on cavity-wall, have been estimated in sinusoidal field profile. For the typically chosen non-tapered cavity, the calculated value of ohmic quality factor, in the present paper, was found within 4% of the results calculated using two of previously published expressions. The validation/ comparison of results against simulation software: MAGIC have been made and found within 3%. Further, the effect of structure dimensions, namely, length of mid-section of the cavity, input-taper angle and output-taper angle, on value of the ohmic quality factor for a tapered gyrotron cavity have been studied. It is found that the ohmic quality factor for a tapered gyrotron cavity, other parameters remaining constant, increases with decrease of length of mid-section and input-taper angle, and with increase of output-taper angle. Out of input- and output-taper angles, the latter was found more sensitive controlling parameter for the ohmic quality factor and hence frequency selectivity as well as ohmic heating in a tapered cavity. Furthermore, the contours of length of mid-section and ohmic quality factor were plotted to provide flexibility to the designer in optimising the structure parameters of tapered cavity of a gyrotron.

4 illus, 22 ref

000121   Hossain N;Mishra V;Hasnayeen M A;Faidz A R (Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor, Malaysia, Email: faidzrahman@mmu.edu.my) : Modeling of the power budget of remotely pumped long haul OFCS incorporated with pre-EDFA and DRA. Asian J Phys 2008, 17(2), 253-62.

Focuses on the modeling of the power budget of remotely pumped long haul optical fiber communication system (OFCS) incorporated with an Erbium doped fiber amplifier in the pre-length (Pre-EOFA) and distributed Raman amplifier (DRA). Signal loss in the post- and pre-length as well as signal gain by the Pre-EOFA and ORA are simulated to determine the maximum achievable transmission distance of a remotely pumped long haul OFCS incorporated with pre-EDFA and ORA. Design parameters of pre-EOFA are optimized using the numerical simulation of EOFA rate equation model in order to optimize the pre-EOFA. ORA mathematical model is solved numerically to analyze the signal propagation characteristics through the pre-length due to ORA. The results obtained from the numerical simulation of EDFA and DRA mathematical model are used in the modeling of the power budget of remotely pumped long haul OFCS incorporated with pre-EOFA and ORA. The developed model can be used to design and analyze the performance of a long haul OFCS link and to optimize the system performance.

7 illus, 2 tables, 14 ref

000120   Dixit M;Lakhtakia A (CATMAS - Computational & Theoretical Materials Sciences Group, Enginee, Pennsylvania State University, University Park, PA 16802-6812, USA, Email: akhlesh@psu.edu) : Electrically controlled Bragg resonances of an ambichiral electro-optic structure: oblique incidence. Asian J Phys 2008, 17(2), 213-23.

The Pockels effect can increase the effective birefringence of ambichiral, electro-optic rejection filters made of maªterials with a 42m point group symmetry, when a de electric field is applied parallel to the axis of non homogeneity. The reflectances and the transmittances of such an ambichiral structure for obliquely incident plane waves are solvable through a boundary-value problem that is formulated using the frequency-domain Maxwell equations, the constitutive equations that contain the Pockels effect, and standard algebraic techniques for handling 4x4 matrix ordinary differential equations. The Bragg resonance peaks, for different circular-polarized-incidence conditions, blueshift as the angle of incidence increases. These blueshifts are unaffected by the sign of the dc electric field.

7 illus, 12 ref

000119   Das S R (Physics and Astronomy Dep, University of Kentucky, Lexington, KY 40506, USA, Email: das@pa.uky.edu) : String theory and cosmological singularities. Pramana J Phys 2007, 69(1), 93-108.

In general relativity space-like or null singularities are common: they imply that 'time' can have a beginning or end. Well-known examples are singularities inside black holes and initial or final singularities in expanding or contracting universes. In recent times, string theory is providing new perspectives of such singularities which may lead to an understanding of these in the standard framework of time evolution in quantum mechanics. Describes some of these approaches.

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000118   Chaubey V K (Electical & Electronics Engineering Group, Birla Institute of Technology and Sciences, Pilani-333 031, Email: vke@bits-pilani.ac.in) : Modeling and simulation of all-optical intelligent routed networks under traffic control protocols. Asian J Phys 2008, 17(2), 245-52.

The network protocol and efficient node architecture increases the data transport capability of an optical wavelength division multiplexed system. Presents a simple analytical model for an optical router capable of implementing specific routing algorithm controlled by efficient protocols. The router is modeled as a processor to implement the instructions through appropriate optical hardware components to support packet stacking, switching or routing the bursty traffic. An analytical node model has been developed to simulate the traffic throughput under the appropriate link and node operating conditions. The node performance for the source initiated and the destination initiated protocols has been reported to show the superiority of the performance through bandwidth utilization via reservation control protocols. The simulation results validate their analytical model and show that the network performance is well-controlled by the Implemented protocols and network design parameters.

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000117   Brill D;Khetarpal P;Kaul V (Physics Dep, University of Maryland, College Park, MD 20782, USA, Email: brill@physics.umd.edu) : Horizons in 2+1-dimensional collapse of particles. Pramana J Phys 2007, 69(1), 109-18.

A simple, geometrical construction is given for three-dimensional spacetimes with negative cosmological constant that contain two particles colliding head-on. Dependªing on parameters like particle masses and distance, the combined geometry will be that of a particle, or of a black hole. In the black hole case the horizon is calculated. It is found that the horizon typically starts at a point and spreads into a closed curve with corners, which propagate along spacelike caustics and disappear as the horizon passes the particles.

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000116   Ashtekar A (Institute for Gravitational Physics and Geommetry, Physics Dep, Penn State University, University Park, PA 16802, USA) : Black hole dynamics in general relativity. Pramana J Phys 2007, 69(1), 77-92.

Basic features of dynamical black holes in full, non-linear general relativity are summarized in a pedagogical fashion. Qualitative properties of the evolution of various horizons follow directly from the celebrated Raychaudhuri equation.

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000115   Ahmadi N;Nouri-Zonoz M (Physics Dep, University of Tehran, North Karegar Ave., Tehran 14395-547, Iran, Email: nahmadi@ut.ac.ir) : Raychaudhuri equation in quantum gravitational optics. Pramana J Phys 2007, 69(1), 147-57.

The equation of Raychaudhuri is one of the key concepts in the formulation of the singularity theorems introduced by Penrose and Hawking. Taking into account QED vacuum polarization, studies the propagation of a bundle of rays in a background gravitational field through the perturbative deformation of Raychaudhuri's equation. In a sense, this could be seen as another semiclassical study in which geometry is treated classically but matter (which means the photon here) is allowed to exhibit quantum characteristics that are encoded in its coupling to the background curvature.

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