012496   Ashok Kumar (Univ Physics Dep, N. Mandal Univ, Laloo Nagar, Madhipura) : Determination of surface impedance of a planar boundary from the remote field measurements. Acta Cienc Indica-Phys 2006, 32(4), 423-8.

A method to determine the surface impedance of a planar boundary from the remote field measurement is described. The surface impedance is recovered from the boundary condition itself which requires knowledge of the field distribution and its derivative on the surface. The measured data is analytically continued to the boundary to obtain the required field expressions.

3 illus, 6 ref

012495   Angelsky O V;Ushenko A G;Ushenko Y A;Ushenko Y G;Tomka Y Y (NO, Chernivtsi National Univ, 2 Kotsyubinsky Str. Chernivtsi, Ukraine, 58012, Email: ushenko-bio@itf.cv.ukrtel.net) : Polarization correlometry of biological tissue speckle-images and diagnostics of their physiological state III. Polarization-correlation structure of speckle-images of biological tissues birefringent nets and their pathological changes diagnostics. Asian J Phys 2006, 25(1), 49-54.

3 illus, 3 tables, 2 ref

012494   Angelsky O V;Ushenko A G;Ushenko Y A;Ushenko Y G;Tomka Y Y (NO, Chernivtsi National Univ, 2 Kotsyubinsky Str. Chernivtsi, Ukraine, 58012, Email: ushenko-bio@itf.cv.ukrtel.net) : Polarization correlometry of biological tissue speckle-images and diagnostics of their physiological state II. Complex degree of mutual polarization (CDMP) of biological tissue speckle-images. Asian J Phys 2006, 25(1), 41-7.

2 illus, 2 tables, 11 ref

012493   Angelsky O V;Ushenko A G;Ushenko Y A;Ushenko Y G;Tomka Y Y (NO, Chernivtsi National Univ, 2 Kotsyubinsky Str., Chernivtsi, Ukraine, 58012) : Polarization correlometry of biological tissue speckle-images and diagnostics of their physiological state. Asian J Phys 2006, 25(1), 29-39.

Investigation of the statistical polarization and correlation structure of speckle-images of biological tissues with different morphological structure. It consists of three parts: first part (I) outlines the results of polarization coordinate mapping and analysis of the statistics of the first-fourth orders of biological tissues polarization azimuth and ellipticities. The second part (II) is directed to study of statistics of the complex degree of mutual polarization of biological tissues speckle-images. In the third part (III) of the paper the diagnostical possibilities of polarization-correlometry of speckle-images which correspond to physiologically normal and degeneratively-dystrophycally changed biological tissues being analyzed.

6 illus, 1 table, 9 ref

012492   Amutha R;Subbarayan A;Sathyamoorthy R (P.G. Physics Dep, Kongunadu Arts & Science College, Coimbatore-641 029) : Structural properties of evaporated ZnTe thin films. Acta Cienc Indica-Phys 2006, 32(4), 445-50.

ZnTe thin films were prepared on the well-cleaned glass substrates under a pressure of bar by vacuum evaporation method. The thickness of the film was measured by multiple interferometer (MBI) technique. The structural characterization was performed by X-fay diffraction method(XRD). The diffractograms show that the films of higher thickness 'exhibit crystalline nature where as those of lower thickness the amorphous structure. The rain (e), grain size (D), and dislocation density ?? were calculated and results are cussed. The surface morphology of the films was studied by scanning electron microscope '(SEM). The average roughness and the root mean square roughness have been calculated using atomic force microscope (AFM).

4 illus, 15 ref

010468   Yadav M;Chauhan D S (Department of Physics, Govt P.G. College, Kotdwara, Pauri Garhwal-246 149) : Propagation of freely propagating weak cylindrical shock waves. Acta Cienc Indica-Phys 2005, 31(4), 525-32.

Using CCW method an attempt has been made to study the propagation of freely propagating weak cylindrical shock waves through rotating and ideal gas at permissible shock front locations for an arbitrary initial, density distribution of the form, say, p₀ = p'log (1 + λr), where p' is the density at the axis of symmetry and λ is non-dimensionalyzing constant. The numerical estimate of the flow variables have been computed at only on those values of propagation distance r which are permitted by the entropy distribution condition. The result obtained has been presented through graphs.

5 illus, 16 ref

010467   Yadav D N P;Prasad R N (NO, , Sahugarh (Hulas Tola), Madhipura, Bihar) : Study of minimum possible antenna qualityfactor. Acta Cienc Indica-Phys 2005, 31(4), 495-7.

The analytical review of minimum possible antenna quality factor for both directional and omnidirectional antennas has been presented. The antenna attains the lowest quality factor if TE_1M in TM_1M modes are equally excited. The existence of a lower bound for antenna Q means that the stored energy around antenna can never be made to zero or arbitrarily small. If the antenna radiates TE modes or TM modes, then their a_n or b_n will be zero and in both cases it can be shown that minimum possible Q is given by Q^TE = min Q^TM = 1/k_a + 1/(k_a)³. For both directional and omnidirectional antennas, the minimized Q is the same as minimum possible Q.

1 illus, 9 ref

010466   Yadav D N P;Prasad R n (NO, , P.O. sahugarh (Hulas Tola), Bihar) : Study of directivity of antenna. Acta Cienc Indica-Phys 2005, 31(4), 445-8.

The directivity of antenna has been presented. Recent interest in communication applications has increased the need of system engineers to measure accurately the directivity of antenna. Authors have derived simple directivities formulas for various practical situations. Many other formulas are limited to special cases. Also authors assume only the knowledge of bandwidth values and the knowledge of the general form of the pattern. When generalized to include unbalanced E- and H-plane bandwidth, it can be used to approximate a variety of antenna patterns. The attraction of this model is that there is simple analytical formula for the directivity. If only the half-power bandwidths in the principal plains are available, the directivity must be estimated using this model. If no sidelobes are present, the desired approximations can be used. For theoretical patterns with perfect nulls and sidelobes decrease away from the main beam.

8 ref

010465   Yadav B S;Nitin Kumar (Molecular Spectroscopy & Bio Physics Lab, D.N. (P.G.) College, Meerut) : Solvent effect on electronic spectra of 2,4, Di nitro-5-fluoro aniline. Acta Cienc Indica-Phys 2005, 31(4), 539-42.

The electronic spectra of 2, 4-di nitro-5-fluoro aniline was recorded in various solvents in the region 190-400 nm. The group sensitive fundamental are compared with those of the similar molecules already reported in the literature.

4 illus, 17 ref

010464   Weber A I (NO, , 303, Brooksby, Village Drive # 321 Peabody, M.A. 01960, U.S.A) : Weber's cataclysmic collision theory. Acta Cienc Indica-Phys 2005, 31(4), 543-7.

2 tables

010463   Vaidya S V (Department of Physics, Saraswati Bhuwan College of Science, Aurangabad-431 001) : Formulation of massive electrodynamics with single potential. Acta Cienc Indica-Phys 2005, 31(4), 517-24.

Dirac-Maxwell's classical electrodynamics is well expressible into tensor and covariant form [1-3] and is very convenient to handle its mathematical details in compact and concise way. Develops such covariant and tensor form for four-component electrodynamics with single potential.

8 ref

010462   Singh N K;Shahabuddin M (University Department of Physics, V.K.S. University, Ara-802 301) : Synthesis, structural and electrical characterization of Gd₂(Ba_0.5W_0.5)₂O₇ ceramics. Acta Cienc Indica-Phys 2005, 31(4), 449-58.

The polycrystalline sample of pyrochlore-type Gd2 (Ba_0.5W_0.5)₂O₇ (GBM) compound was synthesized by solid-state reaction technique. Preliminary, room temperature X-ray studies suggest the formation of single phase desired compound with cell parameters a = 11.691 (2) Angstron, b = 7.023 (5) Angstron and c = 13.864 (2) Angstron in the orthorhombic crystal structure. SEM study with different magnifications provides information on quality of the sample and the uniform grain distribution over the entire surface of the sample. Detailed studies of the dielectric constant (ε) and loss tangent (tan δ) of GBW as a function of frequency (0.1 kHz to 100 kHz) at room temperature (23°C) and as a function of temperature (RT to 350°C) at different frequencies suggest that the compound do not have any dielectric anomaly in the studied frequency and temperature range. Ac conductivity has been studied over a wide range of temperature. Variation of dc resistivity with electric field (0.5-50V/cm) at different temperatures and variation of dc resistivity with temperature (RT-370°C) at constant electric field of 60 V/cm showed the low-activation energy semiconductor characteristics of the material.

8 illus, 2 tables, 18 ref

010461   Singh G;Pawan Kumar;Singh V;Arvind Kumar; Bhattacharya B (Department of Physics, S.G.(P.G.) College, Saroorpur (Khurd), Meerut) : The band edge modulation in chemically grown ZnS nano particles. Acta Cienc Indica-Phys 2005, 31(4), 559-62.

The zinc sulphide nano particles have been prepared chemically in methanolic solution of ZnCl₂. Sulphur exchange was achieved by the controlled reaction of Na₂S. The UV/Visible absorption spectra have been obtained in the range 450 nm to 250 nm. Authors reported that the band gap of the bulk compound gradually increases with the decrease in the size of the particle and finally in merges to the molecular homo-lumo type of structure. A comparison to the result has been made with our earlier reports on CdS nano particles.

010460   Shanker R;Sinha S P;Singh J P;Singh K K; Prasad S N;Mishra L K (Department of Physics, College of Commerce, Patna) : Study of density and quasi-particle excitations and evaluation of dynamical structure factor s(Q, ω) of roton in liquid. Acta Cienc Indica-Phys 2005, 31(4), 473-80.

Using Glyde and Griffin formalism, authors have studied the density and quasi-particle excitations in liquid ⁴He. Authors have also evaluated dynamic structure factor S (Q, ω) of roton as a function of energy at a fixed temperature and momentum transfer k. The evaluated results are in good agreement with those of the other workers and experimental data.

1 table, 32 ref

010459   Shanker R;Sinha S P;Singh J P;Singh K K; Prasad S N;Mishra L K (Department of Physics, College of Commerce, Patna) : Study of density and temperature dependence momentum distribution and evaluation of condensate fraction as a function of density in ligand <. Acta Cienc Indica-Phys 2005, 31(4), 467-72.

Evaluates the condensate fraction n₀ as a function of temperature T at fixed density and n₀ as a function of density at fixed temperature in liquid ⁴He Both-results give same type of behaviour, n₀ is maximum at lower temperature and lower density. This results are consistent with the results of other workers.

2 tables, 44 ref

010458   Rajamannan B;Viruthagiri G;Balachandramohan M;Krishnan A (Department of Physics, Annamalai University, Annamalainagar-608 002) : Use of grog addition as ceramic brick material. Acta Cienc Indica-Phys 2005, 31(4), 577-81.

An attempt has been made to calculate the mechanical property of the fired samples and also to correlate the strength of the samples with the different proportions of the Grog contents.

5 illus, 1 table, 16 ref

010457   Rajamannan B;Krishnan A;Ponnarasan V; Viruthagiri G;Balachandramohan M (Department of Physics, Annamalai University, Annamalainagar-608 002) : Ultrasonic characterization of green and sintered traditional ceramics. Acta Cienc Indica-Phys 2005, 31(4), 555-8.

Presents a study on the influence of porosity level on Young's modulus and Poisson's ratio of green and sintered traditional ceramics. A Non-destructive technique, ultrasonic waves was used to determine the different parameters. Longitudinal and transverse wave velocities are measured by through transmission method at two frequencies namely 0.5 and 5 MHz for green and sintered respectively. The Young's modulus and Poisson's ratio were calculated from the measured velocities.

3 tables, 9 ref

010456   Pandey Munish M S;Singh R P;Jha G C;Mishra L K (Department of Physics, Magadh University, Bodh-Gaya-824 234) : An evaluation surface red <116> (<119>) and Y(<119>) as a function of (<119>)/(<119>p) for metals. Acta Cienc Indica-Phys 2005, 31(4), 459-65.

Surface response function Red<116> (ω) and Y (ω) as a function (ω/ω_p) for metal has been calculated by using Feibelman formalism (Δm). The real part measures the dipole length of the optically induced charge density and the imaginary part is realated to the optical absorption of the surface region. The theretical results are in good agreement with those of the other workers.

2 tables, 45 ref

010455   Nithiyanatham S;Palaniappan L (Department of Physics, Annamalai University, Annamalainagar-608 002) : Ultrasonic study on glucose with α amylase in aquenous media. Acta Cienc Indica-Phys 2005, 31(4), 533-8.

The ultrasonic velocity, density and viscosity at 303 K have been measured in the ternary system of glucose with α-amylase in aqueous medium. The acoustical parameters such as adiabatic compressibility, free length, free volume and internal pressure are calculated. The results are interpreted in terms of molecular interaction between the component of the mixtures. The existence of strong interactions are confirmed by the observed excess values.

4 illus, 2 tables, 23 ref

010454   Mamta Kumari;Rafique S M;Prasad H S (P.G Department of Physics, T.M. Bhagalpur University, Bhagalpur-812 007) : Energetics of pseudopotential calculations: electrical resistivity & Knight shift of liquid metals. Acta Cienc Indica-Phys 2005, 31(4), 481-5.

The more rigorous and less commonly used Harrison's First Principle (HFP) technique has been used to study the liquid electrical resistivity and Knight shift of polyvalent liquid metals with special reference to the energetics of the core electronic states. The role of self consistently computed core energy eigenvalues has been studied in respect of the non-local screened form factor and the computed properties. Reasonable agreement with experiment has been obtained.

1 illus, 2 tables, 20 ref

010453   Kumar S;Verma V K;Mishra L K (Department of Physics, Magadh University, Bodh-Gaya-824 234) : Quantum mechanical study of a chargeless spinning particle in a periodic magnetic field. Acta Cienc Indica-Phys 2005, 31(4), 551-4.

Using the theoretical formalism of Miguel Calvo, authors have studied the quantum mechanics of a chargeless spinning particle in a periodic magnetic field. The study indicates that it is an exactly soluble system and its solution will generate some very interesting physical aspects.

8 ref

010452   Kumar S;Verma V K;Mishra L K (Department of Physics, Magadh University, Bodh Gaya-824 324) : Studies of diamagnetic behaviour of free electron gas in an external helical magnetic field. Acta Cienc Indica-Phys 2005, 31(4), 487-93.

Using the theoretical formalism of Miguel Calvo, studied the diamagnetic behaviour of free electron gas in an external helical magnetic field. The study reveals the fact that at low temperature Fermi energy 'μ' becomes a function of external magnetic field. The susceptibility is negative and decreases as B₀^-4. The results are in good agreement with that of other workers.

16 ref

010451   Kar M;Thakur K;Zadgaonkar A S (NO, Engineering College, Raipur) : Design of low pass fir digital filter using combination of hamming & boxcar window function. Acta Cienc Indica-Phys 2005, 31(4), 513-6.

Aimed to design a low pass FIR digital filter using new window function. This is nothing but combination of Hamming window function and Boxcar window function. Digital filter is a digital system that can be used to filter discrete time signals. Digital filters are classified either as finite duration unit impulse response (FIR) filters or infinite duration unit pulse response (IIR). Proposed low pass FIR filter designing. There are numerous methods available for designing of Low pass FIR filters, window techniques is one of them. There are mostly six types of window technique i.e. Rectangular (Boxcar) window function, Hamming window function, Hamming window function, Blackman window function, Bartlett window function, Kaiser-Bessel window function. Designed FIR filter using MATLAB Software. One of the main characteristics of MATLAB is the availability of a set of toolboxes almost ready to be used in the design of filters. MFILTERS is organized around the MATLAB signals toolbox. The idea behind MFILTERS is to take advantage of the expertise already available in this toolbox. The advantage of designing filters in this way is twofold: first, we do not have to program each and every equation. That could take a considerable length of time to do and second, by using this well proven toolbox, we guarantee that there are new errors introduced by programming everything ourselves. It is observed that there is increase in the pass band width of low pass FIR filter using the new window function. The characteristics of fixed window function Hamming and Boxcar, are compared with new proposed window function i.e. combination of Hamming and Boxcar. Thus it is concluded that this new window function will have a better response in the pass band edge, and also the ripple are less.

3 illus, 2 tables, 4 ref

010450   Jha V K;Jha G K;Jha H K (University Department of Physics, L.M.N.U., Darbhanga) : Study of new model for rain-drop size distribution. Acta Cienc Indica-Phys 2005, 31(4), 509-11.

A new model for the rain-drop size distribution has been presented. A negative exponential rain drop size distribution model, suitable for the user in tropical and climatic environment has been developed. The model applicable in the frequency band of 10-40 GHz and can be used for communication links employing horizontal, vertical & circular polarization. The model has been developed on the basis of data collected and T-matrix computation of total extinction cross sections of raindrops. Plots of rain attenuation versus rain rate for selected frequency has also been presented.

2 illus, 6 ref

010449   Jha R K;Chaudhary N N (Department of Physics, M.L.S.M. College, Darbhanga) : Critical analysis of multilayered broad-band microstrip antenna. Acta Cienc Indica-Phys 2005, 31(4), 563-6.

Microstrip antennas possess many advantages such as mass production, small volume, low profile and light weight. Thus, they have attracted the attention of modem engineers and researchers to investigate these types antennas of various configurations to meet various practical applications. But such type of antennas have the narrow bandwidth which is one of the important features that restricts the development and practical use of this type of antenna in modern communication processes. A simple and practical method for the design of broad-band microstrip antenna has been presented. Utilizing this design technique, several two-layered microstrip antennas have been proposed. Used simulation method to calculate the different characteristic parameters of the proposed microstrip antenna. The simulated results show that the proposed antennas have a bandwidth of upto 26 percent. Also, the method proposed is applicable to the design of other types of multilayered planar antennas.

2 illus, 7 ref

010448   Jha B K;Mahto D;Jha G K;Thakur B;Prasad U (University Department of Physics, L.N.M.U., Darbhanga) : Theoretical calculation of average binding energy per necleon using linked cluster perturbation series expansion. Acta Cienc Indica-Phys 2005, 31(4), 567-9.

Calculates moments in the unit of Fermi momentum, energies in the unit of Fermi energy, lengths in the unit of inverse of Fermi momentum and velocity of zero sound mode in the unit of Fermi energy. Finds expression for E₀ (k_c) in a dimensionless form for the calculation of binding energy per nucleon using modified values of some parameters. Also calculates the average binding energry per nucleon using Linked cluster perturbation series expansion which is very close to the experimental values found in literature.

1 illus, 8 ref

010447   Jha A K;Alam S (Department of Physics, J.M.D.P.L. College, Madhubani, Bihar) : Study of scattering for dielectric cylinder. Acta Cienc Indica-Phys 2005, 31(4), 441-4.

A method for reconstructing the shape and the permittivity of a penetrable homogeneous cylinder has been described. A low-frequency approximation is used to determine an initial guess. Then, a rigorous boundary integral method permits us to reconstruct arbitrary shapes and complex permittivities. It is based on an iterative conjugate gradient algorithm requiring to solve two direct diffraction problems only. A simple and original regularization scheme has been presented, that ensures the robustness of the algorithm. Numerical examples with lossy embedding media and additional random noise for both E// and H// polarizations have been presented.

1 illus, 6 ref

010446   Biswal S;Pradhan M;Sahoo P K (Department of Physics, Nayagarh College, Nayagarh-752 069) : Transmission of thermal energy in magneto-hydrodynamic unsteady free connective flow of mercury and liquid sodium past in infinite porous flat plate in presence of heat absorbing sinks with constant suction. Acta Cienc Indica-Phys 2005, 31(4), 571-6.

The computational analysis of heat transfer in the unsteady free connective flow of mercury and liquid sodium past an infinite vertical plate with constant suction and heat absorbing sinks has been carried out in presence of an external transverse magnetic field. Approximate solutions have been derived for the velocity and temperature fields, mean skin-friction and mean rate of heat transfer. It is observed that increase in magnetic field strength decreases the mean skin-friction and mean rate of heat transfer both for mercury and liquid sodium.

3 illus, 1 table, 15 ref

010445   Apte V M (NO, , ) : Understanding gravity and geodesy for navigation and precise targeting. Indian Surveyor 2006, 60(1), 51-7.

Introduces the role of Eaerth's gravity on the selection of geodetic datums, and its eventual impact on mapping/charting and precise targeting of weapons. Thereafter a three-point approach to solving the problem of precise targeting has been described.

4 illus

010444   Anil Kumar;Shiv Singh;Rakesh Kumar (Department of Physics, Hindu College, Moradabad) : Quasi positive delta sequences for wavelet packets. Acta Cienc Indica-Phys 2005, 31(4), 499-507.

Wavelet is a tool for analyzing and manipulation of signals. First the definition of a multiresolution analysis is given and how wavelet fit into it, is shown. Introduces a technique to form wavelet packets using quadrature mirror filters. By using orthonormal wavelet packets, we shall study the pointwise convergence properties and some results regarding quasi positive delta sequences have been studied.

13 ref

009371   Wahiddin M R B;Abdel Aty M;Abdel Hameed H F; Obada A S F (Centre for Computational and Theoretical Sciences, Kulliyyah of Scienc, International Islamic University Malaysia, 53100, Kuala Lumpur, Malaysia) : Mixedness and entanglement of an analytically solvable time-dependent ion-field interaction. Indian J Phys 2006, 80(5), 449-62.

A theoretical investigation of the interaction between trapped ions and an external laser field beyond the Lamb-Dicke regime taking into account the time-dependent ion-field coupling is reported. At exact resonances the time-dependent ion-field interaction is analytically solvable. Focuses on the role of different parameters in the phenomenon of collapses and revivals of the Rabi oscillations. In the case of an initial pure state, we account for a number of interesting phenomena including revivals which are determined by the initial photon-number distribution. Starting with an initial coherent state for the center-of-molion quantized modes, and the ion in its upper state, we demonstrate the existence of super-revivals. Briefly explains the statistical basis of the measures of mixedness and entanglement. The general results are illustrated using pure and mixed state density matrices of the composite system. Some applications are provided and discussed in detail, bringing to light the feasibility and the wide potentiality of the different forms of the entanglement measures. It is found that the time evolution of the quantum linear entropy systematically captures the corresponding collapse and revival features in the atomic inversion. Also shows that the degree of entanglement of the ion-field system, for the initial mixed state, can be completely quantified by the quantum mutual entropy. The analysis shows that the entanglement degree due to the quantum mutual entropy exhibits new features in the time-dependent case.

10 illus, 65 ref

009370   Thapa R K;Gurung S R;Das G;Bhattacharjee R (Department of Physics, Mizoram University, Tanhril-796 009, Mizoram) : Calculation of photocurrent in Al and Be by using the free electron potential model for the crystal. Indian J Phys 2006, 80(4), 361-6.

Uses free electron model potential in the calculation of photocurrent from metals like aluminium and beryllium by using a spatially dependent vector potential. The results had been compared with the one calculated by using the dielectric model as proposed by Bagchi and Kar.

6 illus, 24 ref

009369   Tamuly T;Baruah G D (Department of Physics, Dibrugarh University, Dibrugarh-786 004) : Comparative study between autler-townes splitting and quenching of spontaneous emission. Indian J Phys 2006, 80(5), 531-5.

Modification of spontaneous emission is an active research topic in quantum optics. The three-peak spectrum of resonance fluorescence was one of the first development in the area. Cavity electrodynamics has made possible the enhancement and suppression of spontaneous emission from an atom via a tailoring of the mode density. Eliminations of resonance fluorescence from a driven three-level atom was proposed in. Dynamical suppression has also been achieved from a driven, cavity-confined, two-level atom. Furthermore, it has been predicted and experimentally demonstrated that three level atoms can exhibit a narrowing of spectral linewidth on one transition controlled by coherent driving another transition. The coherent preparation of atomic state essential for this can be realized via Autler-Townes splitting. Works out a correlation between Autler-Townes splitting and quenching of spontaneous emission via quantum interference. It is believed that the present correlation will be helpful in understanding the process of lasing without inversion.

2 illus, 28 ref

009368   Talukdar B (Department of Physics, Visva-Bharati, Santineketan-731 235, Email: binoy123@sancharnet.in) : Inverse variational problem for nonlinear equation in optics. Indian J Phys 2006, 80(5), 501-4.

Based on certain crucial observations on the symmetries of the Lagrangian and those of the corresponding equation of motion, an uncomplicated method is derived to deal with inverse problem of variational calculus. It is pointed out that the present approach will play a significant role in the study of pulse propagation through fibers. Some useful results are obtained for envelope equations in nonlinear couplers.

6 ref

009367   Syal V K;Chauhan A;Chauhan S (Department of Chemistry, H.P. University, Summer Hill, Shimla-171 005, Email: vijay_syal@indiatimes.com) : Solutions of poly (vinylpyrrolidone) in binary mixtures of DMSO+H_2O at different temperatures by ultrasonic velocity measurements. Indian J Phys 2006, 80(4), 377-85.

The ultrasonic velocities and densities of solutions of poly (vinylpyrrolidone) i.e. (PVP) (Mol. wt ≅ 40.000) have been measured in water and its binary mixtures with dimethylsulphoxide (DMSO) containing DMSO at 25 mol % intervals at 25°C,35°C and 45°C. From velocity and density values, various acoustical parameters such as acoustical impedance (Z), adiabatic compressibilily (β), intermolecular free length (L_f), relative association (R_Λ), molar sound velocity(R), Wada's constant (W), solvation number (S_n) and apparent molar adiabatic compressibilty (φ_SA) have been evaluated. All these parameters have been discussed separately in terms of polymer -polymer and polymer- solvent interactions as a function of solvent composition and temperature.

2 illus, 5 tables, 16 ref

009366   Singh R P;Roychowdhury S;Jaiswal V K (Division of Quantum Optics and Quantum Information, Physical Research, , Navrangpura, Ahmedabad-380 009) : Optical vortices produced by forked holographic grating and sign of their topological charge. Indian J Phys 2006, 80(5), 491-4.

Produces optical vortices using a computer generated hologram (CGH) having a forked grating. Proposes to use free space trajectory of the vortex produced for assigning sign to topological charge associated with the vortex. Finds experimental trajectory of the vortex that is matched with theoretical trajectory for negative as well as positive charge obtained with Collins integral formalism for vortex propagation. This match is used to determine the sign of the vortex charge unambiguously.

6 illus, 17 ref

009365   Sharma S;Ghoshal S K;Devendra Mohan (NO, Guru Jambheshwar University, Hisar-125 001, Email: Sun_phy2003@yahoo.com) : Damping effect on power loss in optical fibers due to higher order nonlinear term. Indian J Phys 2006, 80(5), 523-6.

The nonlinear response of optical fiber based on anharmonic oscillator model is investigated analytically and numerically. The response of the fifth order nonlinear refractive index with the frequency of LASER at 1.33μm is examined. The work is motivated from a number of theoretical and experimental studies on power loss in optical fiber. The power loss due to imaginary part of fifth order nonlinear refractive index for Pure Silica Core Fiber, Dispersion Shifted fiber and Dispersion Compensating Fiber is calculated. The variation of power loss with damping constant is also calculated at 2 mW. Finds a finite contribution due to fifth order anharmonic term. Controlling such nonlinearity is very important for technological applications.

5 illus, 3 tables, 5 ref

009364   Sen B;Mandal S (Department of Physics, Visva Bharati, Santimketan-731 235, Email: swapanvb@rediffmail.com) : Nonclassical photon statistics in spontaneous Raman and in stimulated Raman processes. Indian J Phys 2006, 80(5), 545-9.

The equations of motion of the field operators corresponding to the spontaneous and stimulated Raman processes give rise to the coupled nonlinear differential equations. The solutions of these coupled differential equations involving field operators are used to calculate the second order correlation function for zero time delay and hence the photon-bunching, photon-antibunching and nonclassical photon statistics of the input coherent light.

1 illus, 27 ref

009363   Selvanayagam S;Velmurugan D;Yamane T (Department of Crystallography and Biophysics, University of Madras. Guindy Campus, Chennai-600 025, Email: d_velu@yahoo.com) : Direct phasing of one-wavelength anomalous scattering data: a high throughput tool in structural genomics. Indian J Phys 2006, 80(4), 347-55.

The available macromolecular sequence information exceeds far in number the available three-dimensional structures. High throughput techniques are hence necessary to unravel the three-dimensional structures of selected macromolecular sequences in the area of Structural Genomics in a short time. The structure solution program SHELXD is useful for locating the anomalous scatterers from SIR, SAS, S1RAS or MAD data. SHELXE estimates the native phases and the weights from SHELXD. OASIS is a computer program for breaking phase ambiguity in one wavelength anomalous scattering data. The phases obtained from SHELXE and OASIS are of superb quality to allow automated model building to be carried out in ARP/wARP. Attempts are here made in extending the applications to the high throughput structure elucidation of thermolysin of approximately 34 kDa molecular weight using 1.7 Angstron single wavelength anomalous scattering (SAS) data and 2 Angstron truncated data and also of glucose isomerase of approximately 44 kDa molecular weight using 1.45 Angstron SAS data.

2 illus, 2 tables, 11 ref

009362   Sarkar U;Chattaraj P K (Department of Chemistry, Indian Institute of Technology, Kharagpur-721 302) : Dynamic reactivity profiles of helium and neon atoms interacting with an intense laser field. Indian J Phys 2006, 80(5), 463-70.

Time evolution of various reactivity parameters like chemical potential, hardness, electrophilicity, phase volume etc. has been studied for the helium and neon atoms when they interact with an external intense laser field, within a quantum fluid density functional framework. The tug-of-war between the classical nuclear Coulomb potential and the potential due to the external field is clearly manifested. Corresponding Rydberg state dynamics of helium atom provides important insights into the associated chaotic ionization.

19 illus, 24 ref

009361   Saha S K (NO, Indian Institute of Astrophysics, Bangalore-560 034) : Laser guide artificial star for high resolution imaging. Indian J Phys 2006, 80(5), 505-9.

A large telescope encodes the information about the source, but is unable to get the diffraction-limited informations. Due to the inhomogeneity of the propagating medium that carries the light to the Earth's surface, the image of a point source (unresolved stars) cannot be smaller than a limit at the focal plane of the telescope. In order to estimate the point spread function of both the atmosphere and the telescope, observation of a bright unresolved star is needed. Astronomers do face difficulties in locating such an object within isoplanatic patch. Over the years, several observatories have developed the laser guide artificial star in order to palliate the limitations of low sky coverage (the probability of finding a suitable reference star within isoplanatic patch). This article discusses the utility of such an instrument.

3 illus, 16 ref

009360   Rajamohan R;Satya Narayanan A (NO, Indian Institute of Astrophysics, Koramangala, Bangalore-560 034, Email: satya@iiap.res.in) : On the rate of change of period for accelerated motion and their implications in astrophysics. Prog Phys 2007, 2(Apr), 65-67.

Derived the relationship that needs to be satisfied when length measurements are expressed in two different units. Interesting relationships emerge when the smaller of the two units chosen is a function of time. Authors relate these results to the expected periodicities in the observed data when a system of objects are revolving around a common center of mass. Authors find that these results are highly intriguing and can equally well account for some of the major results in the field of astrophysics.

009359   Rai H C;Sharan A B;Rai S;Sanjay Kumar (Department of Chemistry, B R A University, Muzaffarpur-842 001, Email: herai_chem@yahoo.co.in) : Vibrational spectral studies on 2,5 dichloroaniline. Indian J Phys 2006, 80(5), 511-15.

Vibrational spectral studies on 2,5-dichloroaniline have been carried out. All the bands have been assigned on the basis of normal coordinate analysis which are in good agreement with the literature. The far IR region (20-600 cm^-1) has been investigated for the first time to pick up such fundamental frequencies which have not been reported so far. The laser Raman spectra of the molecules have been recorded in the region 100-4000 cm^-1.

4 illus, 3 tables, 39 ref

009358   Rai A K;Pandya J N;Vinodkumar P C (Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Anand-388 120) : Low-lying di-hadronic states in relativistic harmonic model. Indian J Phys 2006, 80(4), 387-92.

Di-hadronic molecules such as di-meson, meson-baryon and di-baryon states are studied in the relalivistic confinement model. Computes the binding energy of the di-hadronic systems like K-N, π-N, p- N etc., as penta-quark states, 2π, p-p, K-K*,K*-K*,D-D* etc. as tetra-quark states and N-N, N-Δ, Δ-Δ etc. as di-baryonic states using a molecular interaction provided by asymptotic expression of the confined gluon exchange potential. Finds the lowest penta-quark state lies in the energy range of 1.180 - 2.247 GeV as predicted by other theoretical models. The exotic states such as f₀ (0.982), h₁, (1.170), f₀ (1.70),f₂, (1.565),f₂, (1.95), ψ (4.040) etc. are identified as the di-mesonic hadron molecules. The low-lying di-baryon molecular states found to be in the range of 1.990-2.907 GeV with their binding energies lying between 112-120 MeV.

4 tables, 32 ref

009357   Perinova V;Luks A (Laboratory of Quantum Optics and Research Centre for Optics, Faculty o, Palacky University, Tria Svobody 26, 77146 Olomouc, Czech Republic, Email: perinova@prfnw.upol.cz) : Photon-number distributions in the steady states of traditional and random lasers. Indian J Phys 2006, 80(5), 439-47.

The theory of a laser has provided many semiclassical and quantum models of the laser. Differential-difference equations are used in the description of the dynamics of the laser. Focus on steady state leads to a simplification of these equations to the difference equations. In study of random lasers, traditional laser characteristics randomize, and these variables themselves are characterized after a judicious choice of a model.

6 illus, 10 ref

009356   Pathak A (Department of Physics, Jaypee Institute of Information Technology, A-10, Sector-62, Noida-201 307, Email: anirbanpathak@yahoo.co.in) : Mathematical criterion for single photon sources used in quantum cryptography. Indian J Phys 2006, 80(5), 495-9.

A single photon source (SPS) is very important for quantum computation. In particular, it is essential for secured quantum cryptography. But there is no perfect SPS in reality. Therefore, probabilistic SPS where probability of simultaneous emission of two, three, four and more photon is less than the emission of a single photon are used. Since classical photon always comes in bunch, the required single photon source must be nonclassical. In the well-known antibunched state, the rate of simultaneous emission of two photon is less than that of single photon. But the requirement of quantum cryptography is a multiphoton version of the antibunched state or the higher order antibunched state. Recently we have reported a mathematical criterion for higher order antibunching. Shows that any proposal for SPS to be used in quantum cryptography should satisfy this criterion. Studies four wave mixing as a possible candidate of single photon source.

15 ref

009355   Parashar J (Department of Applied Physics, Samrat Ashok Technological Institute, Vidisha-464 001, Email: jparashar@indiya.com) : Stimulated brillouin scattering and filamentation of two crossed laser beams in a thermal force dominated plasma. Indian J Phys 2006, 80(4), 393-6.

Two crossed laser beams, differing slightly in frequency propagating through a plasma, produces density oscillations at bent frequency via ponderomotive force and nonlinear heating of electrons. The energy exchange between the beams takes place via stimulated Brillouin scattering process. If the two beams are of identical frequencies, the process moves over to filamentation instability.

2 illus, 16 ref

009354   Panigrahy N N;Mahapatra D;Panda B N;Rout G C (Regional Director of Education, , Siddhartha Nagar-2, Berhampur-760 004, Email: nikhil_57@rediffmail.com) : Debye frequency and interplay of superconductivity and antiferromagnetism in high T_c superconductors. Indian J Phys 2006, 80(4), 373-8.

The interplay between superconductivity (SC) and antiferromagnetism (AFM) is studied in strongly correlated systems: R_2-xM_x CuO₄ (R=Nd, La, Pr, Gd; M=Sr, Ce) due to electron-phonon interaction. It is assumed that SC arises due to BCS pairing mechanism in presence of AFM in Cu lattices of Cu-O planes. Debye frequency ωD dependence of high temperature SC gap as well as staggered magnetic field at different temperatures are calculated analytically and solved self-consistently with respect to half-filled band situation for different model parameters (temperature parameter θ and hybridization parameter v, λ1 and λ2 being the SC and AF coupling parameters, respectively). The SC gap and AFM gap are studied in their coexistence phase for different Debye frequencies.

4 illus, 19 ref

009353   Mohan M;Maan A;Jha P (Department of Physics and Astrophysics, Delhi University, Delhi-110 007, Email: sneh@del2.vsnl.net.in) : Control of molecular dynamics in intense laser fields. Indian J Phys 2006, 80(5), 537-43.

In recent years, due to development of ultra-short-pulse laser technology, resulting laser field as high as 10¹⁶ W/cm² can routinely be generated. In such a strong laser field, molecules undergo a variety of nonlinear processes. Many new surprising phenomena have been observed in molecules such as alignment along laser polarization direction, high-harmonic generation, dressed state formation, multiphoton ionization, ultrafast structure deformation, coulomb explosion etc. which are discussed.

4 illus, 36 ref

009352   Mandal P;Bhowmik H;De D;Mukhopadhyay S (Department of Physics & Technophysics, Vidyasagar University, Midnapore-721 102, Email: prasanta_mandal2004@yahoo.co.in) : Study on the propagation of a gaussian soliton pulse through an optical fiber when dispersion is compensated accommodating the nonlinearity of the fiber media. Indian J Phys 2006, 80(5), 527-30.

It is well known that the propagation of soliton pulse through an optical fiber depends on the compensation of Group Velocity Dispersion (GVD) and Self-Phase Modulation (SPM). This balance is to be maintained exactly where in dispersion compensated fiber, the dispersion are balanced mutually that is waveguide dispersion cancels material dispersion. In this context, if we consider the nonlinearity in fiber media, then how these dispersions are compensated mutually, is analytically observed. At the same time, how the soliton pulse will be affected by the media of the optical fiber where the dispersion compensation is done accommodating the nonlinearity of the optical fiber.

5 ref