008926   Jha A K;Jha A;Jha H K (Physics Dep, R. M. College, Saharsa, Bihar) : Study of inverse scattering for one-dimensional permittivity profiles. Indian J Theor Phys 2008, 54(2), 89-96.

A numerical method to invert the dielectric permittivity profile from the Riccati equation using the Newton-Kantorovich iterative scheme has been described. Instead of handling the equations in terms of usual geometrical depth, we determine the profile as a function of the electromagnetic path length since the convergence and the stability of the solution are found to be significantly better in this case. The approach is applicable to both continuous and discontinuous profiles of high contrast and exhibits a good stability of the solution with resect to noisy input data. A lossy medium profile can also be inverted provided the overall thickness of the inhomogeneous slab and the background permittivity are known. When the thickness of the inhomogeneoue layer and the background permittivity are assumed to be known, the permittivity profile is reconstructed accurately whereas for the conductivity profile the method yields qualitative reconstruction. ]

3 illus, 7 ref

008925   Jain N C;Gupta P (Mathematics Dep, Rajasthan Univ, Jaipur-302 004) : Unsteady magnetopolar flow past an infinite porous plate with variable suction / injection and variable permeability. Indian J Theor Phys 2008, 54(2), 129-37.

Examines the analysis of a two-dimensional electrically conducting polar fluid through a porous medium with variable suction / injection and variable permeability bounded by an infinite horizontal porous plate in slip flow regime. The suction / injection on the plate and the permeability of the porous medium decrease exponentially with time. Exact solutions of the mean angular velocity, velocity distribution and skin-friction are obtained. The effects of permeability parameter, couple stress and other parameters entering into the problem are shown graphically and discussed numerically. It is found that when rotational viscosity and couple stress are increased telocity of the fluid is increased.

3 illus, 14 ref

008924   Jahagirdar C J;Tiwari L B (Applied Physics Div, Institute of Chemical Technology, Mumbai Univ, Matunga, Mumbai-400 019, Email: cjjahagirdar@hotmail.com) : Plasma treatment of polyester fabric to impart the water repellency property. Pramana J Phys 2007, 68(4), 623-30.

Polyester fabric is treated with DCDMS solution by two methods: dipping the fabric directly in DCDMS solution for different intervals and dipping the fabric in DCDMS solution after its exposure into RF plasma chamber for different durations at optimized exposure power conditions. The physical properties of polyester fabric treated with DCDMS in the presence or absence of air plasma have been compared with control fabric. Different characterization techniques like scanning electron microscope, attenuated total reflectance-IR and Dataflash 100 colour measurement spectrophotometer are used to assess the surface morphology, composition and change in colour parameters. Water repel-lency property of both untreated and modified polyester fabric is studied using AATCC test method 39 (1971). The effectiveness of the water repellency property of modified polyester fabric is checked by repeated washing up to ten cycles.

4 illus, 4 tables, 6 ref

008923   Islam Z;Ghosh M;Karanjai S (Mathematics Dep, Malda College, Malda-732 101) : Solution of a radiative transfer equation with pomraning phase function and a linear source in a semi-infinite medium. Indian J Theor Phys 2008, 54(3), 193-204.

The equation of radiative transfer with Pomraning phase function and a linear source in a plane parallel semi-infinite atmosphere with axial symmetry has been solved by Laplace transform and Wiener-Hopf technique. We have determined the emergent intensity in terms of Chandrasekhar's H-function and the intensity at any optical depth by inversion.]

13 ref

008922   Hasan T;Singh P K;Misra R;Raj P;Misra N (Physics Dep, Lucknow Univ, Lucknow-226 007, Email: misraneeraj@gmail.com ) : Vibrational dynamics of the organometallic compound triarylorganoantimony (V) SbPh₃[O₂CC (OH) Ph₂]₂. Pramana J Phys 2007, 68(5), 875-80.

A complete normal coordinate analysis was performed for five-coordinate non-rigid triarylantimony diester SbPh₃(O₂CR)₂, known to be a bioactive molecule, using Wilson G-F matrix method and Urey Bradley force field. The study of vibrational dynamics was performed using the concept of group frequencies and band intensities.

1 table, 25 ref

008921   Hamed A M;Saudy M (Physics Dep, Faculty of Science, Ain Shams Univ, Cairo, Egypt, Email: amhamed73@hotmail.com) : Computation of surface roughness using optical correlation. Pramana J Phys 2007, 68(5), 831-42.

The laser speckle photography is used to calculate the average surface roughness from the autocorrelation function of the aluminum diffuse objects. The computed results of surface roughness obtained from the profile shapes of the autocorrelation function of the diffuser show good agreement with the results obtained by the stylus profile meter.

4 illus, 3 tables, 36 ref

008920   Guo Z Z;Wu X W;Wang C A (College of Physics & Electronic Information, Inner Mongolia Normal Univ, Huhhot-010 022, Email: zzguo@imnu.edu.cn) : Damage spreading on networks: clustering effects. Pramana J Phys 2007, 68(4), 689-99.

The damage spreading of the Ising model on three kinds of networks is studied with Glauber dynamics. One of the networks is generated by evolving the hexagonal lattice with the star-triangle transformation. Another kind of network is constructed by connecting the midpoints of the edges of the topological hexagonal lattice. With the evolution of these structures, damage spreading transition temperature increases and a general explanation for this phenomenon is presented from the view of the network. The relationship between the transition temperature and the network measure-clustering coefficient is set up and it is shown that the increase of damage spreading transition temperature is the result of more and more clustering of the network. We construct the third kind of network-random graphs with Poisson degree distributions by changing the average degree of the network. We show that the increase in the average degree is equivalent to the clustering of nodes and this leads to the increase in damage spreading transition temperature.

11 illus, 1 table, 19 ref

008919   Gopinath D V (NO, , No. 208, IV Cross, I Stage, Gangotri Layout, Mysore-570 009, Email: dvgopinath@gmail.com) : Radiation effects, nuclear energy and comparative risks. Curr Sci 2007, 93(9), 1230-48.

Deals with a comprehensive account of effects of the ionizing radiation on living systems. Quantitative description of types of radiation exposure and their varied effects is given. The origin, type and magnitude of mutagenic effects of radiation are described. The concept of radiation risk factors, basis for their evaluation and their currently accepted values are presented. With this background, origin and magnitude of radioactivity and associated ionizing radiations in nuclear reactors are presented and the elaborate measures to contain them are described. It is recognized that notwithstanding all the measures taken in the nuclear industry, certain amount of radiation exposure, however small, is inevitable and the values, based on the experience world over, are presented. Estimated health risk due to such exposures is evaluated. For a comparative analysis, risks in other options of electricity generation such as hydel and fossil-fuelled plants are described. It is seen that on an overall basis, the nuclear option is no more risky than the other commonly employed options, and is in fact, significantly less. Lastly, since every option of electricity generation entails some risk, the case of `no addition of electricity' and its impact on the society are considered. Based on the analysis of extensive data provided by UNDP on the human development parameters for different countries in the world, it is shown that at least for developing countries, any option of addition of electricity would be far more desirable than the `no addition' option, even from health and environmental considerations.

6 illus, 13 tables, 42 ref

008918   Ghosh K (Mathematics Dep, University Institute of Technology, Burdwan Univ, Golapbag (North), Burdwan-713 104, Email: koushikg123@yahoo.co.uk) : Specific angular momentum of the accreting matter around a rapidly rotating non-magnetized degenerate dwarf star of very low mass. Indian J Theor Phys 2008, 54(2), 263-9.

Due to the presence of an accretion disc, the steller angular velocity increases and in the process of increment when the stellar angular velocity reaches to a critical value, a self-consistent regime of accretion ii established, in which the specific angular momentum of the accreting matter equal to the mass derivative of the angular momentum of the stellar body along the sequence of the critically rotating stars An effort is made to search for that expression for specific angular momentum of the accreting matter around ® rapidly rotating non-magnetized degenerate dwarf star of very low mass. A study is made on the existence of a self-similar solution in which the stellar structure and angular velocity law do not depend upon stellar mass for an appropriate choice of non-dimensional variables.]

008917   Ghosh D;Deb A;Pal S;Bhattacharyya S (Physics Dep, Nuclear and Particle Physics Research Centre, Jadavpur Univ, Kolkata-700 032, Email: dipakghosh_in@yahoo.com) : Evidence of self-affine multiplicity scaling of charged-particle multiplicity distribution in hadron-nucleus interaction. Pramana J Phys 2007, 68(5), 789-801.

A self-affine analysis of charged-particle multiplicity distribution (protons + pions) in ρ - AgBr interaction at 350 GeV/c is performed according to the two-dimensional factorial moment methodology using the concept of Hurst exponent in X_cos<113> X_φ phase space. Comparing with the results obtained from self-similar analysis, the self-affine analysis shows a better power-law behaviour. Corresponding results are compared with shower multiplicity distribution (pions). Multifractal behaviour is observed for both types of distributions.

9 illus, 4 tables, 60 ref

008916   George J;Ranganathan K;Nathan T P S (Solid State Laser Div, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: jogy@cat.ernet.in) : Alternative method to specify the degree of resonator stability. Pramana J Phys 2007, 68(4), 571-80.

Present an alternative method to specify the stability of real stable resonatorsAuthor Introduces the degree of optical stability or the 5 parameter, which specify the stability resonators in a numerical scale ranging from 0 to 100%. The value of zero corresponds to marginally stable resonator and 5<60> 0 corresponds to unstable resonator. Also, three definitions of the 5 parameter are provided: in terms of A&D, B&Z_ro and g₁g₂ It may be noticed from the present formalism that the maximum degree of stability with S = 1 automatically corresponds to g₁g₂ = 1/2. Also describs the method to measure the S parameter from the output beam characteristics and B parameter. A possible correlation between the S parameter and the misalignment tolerance is also discussed.

5 illus, 7 ref

008915   Gasilov N (Faculty of Engineering, Baskent Univ, Eskisehir Yolu 20. km, Baglica, 06530 Ankara, Turkey, Email: gasilov@baskent.edu.tr) : Method for calculating active feedback system to provide vertical position control of plasma in a tokamak. Pramana J Phys 2007, 68(4), 591-602.

In designing tokamaks, the maintenance of vertical stability of plasma is one of the most important problems. Systems of the passive and active feedbacks are applied for this purpose. Role of the passive system consisting of a vacuum vessel and passive coils is to suppress fast MHD (magnetohydrodynamic) instabilities. The active feedback system is applied to control slow motions of plasma Investigata two successive problems, solution of which allows to determine the possibility controlling plasma motions. One of these is the problem of vertical stability under the assumption of ideal conductivity of plasma and passive stabilizing elements. The problem is solved analytically and on the basis of the obtained solution a criterion of MHD-stability is formulated. The other problem is connected with the control of plasma vertical position with active feedback system. Calculation of feedback control parameters is formulated as an optimization problem and an approximate method to solve the problem is suggested. Numerical simulations are performed with parameters of the T-15M tokamak in order to justify the suggested method.

3 illus, 13 ref

008914   Gao Y;Xu S P;Zhao B S (College of Science, China Agricultural Univ, P.O. Box 74, Beijing-100 083, People's Republic of China, Email: gaoyangg@gmail.com) : Stress and mixed boundary conditions for two-dimensional dodecagonal quasi-crystal plates. Pramana J Phys 2007, 68(5), 803-17.

For plate bending and stretching problems in two-dimensional (2D) do-decagonal quasi-crystal (QC) media, the reciprocal theorem and the general solution for QCs are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all order. The method developed by Gregory and Wan is used to generate necessary conditions which the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the plate; these decaying state conditions are obtained explicitly for axisyrmnetric bending and stretching of a circular plate when stress or mixed conditions are imposed on the plate edge. They are then used for the correct formulation of boundary conditions for the interior solution. For the stress data, our boundary conditions coincide with those obtained in conventional forms of plate theories. More importantly, appropriate boundary conditions with a set of mixed edge-data are obtained for the first time. Furthermore, the corresponding necessary conditions for transversely isotropic elastic plate are obtained directly, and their isotropic elastic counterparts are also obtained.

26 ref

008913   Feng D;Li J (Center for Nonlinear Science Studies, School of Science, Kunming Univ Science and Technology, Kunming, Yunnan-650 093, China, Email: dahefeng@hotmail.com) : Bifurcation methods of dynamical systems for handling nonlinear wave equations. Pramana J Phys 2007, 68(5), 863-8.

By using the bifurcation theory and methods of dynamical systems to construct the exact travelling wave solutions for nonlinear wave equations, some new soliton solutions, kink (anti-kink) solutions and periodic solutions with double period are obtained.

3 illus, 5 ref

008912   El Aragi G M;Seddik U;Abd El Haliem A (Nuclear Physics Dep, Nuclear Research Centre, Cairo, Egypt, Email: usamasm@yahoo.com) : Detection of accelerated particles from pulsed plasma discharge using solid state nuclear track detector. Pramana J Phys 2007, 68(4), 603-9.

The ion beam of a Mather-type 23.25 J plasma focus device operated with air filling at 10 Torr was registered using CR-39 nuclear track detector. The irradiated samples were etched in NaOH solution at 70degree C for 1 h. It is found here that plasma beam contains multi-components of microbeams. The individual track density of microbeams is estimated and the total current density of the plasma stream is measured to be 1.2 mA/cm². A model for counting the track density of individual microbeams is proposed here. Faraday cup measurements showed the ion pulse with energy ranging from 5.8 keV to 3.3 keV.

8 illus, 7 ref

008911   Dharmendra Kumar;Nabin Kumar (Physics Dep, B.N.M.V. College, Sahugarh, Madhepura, Bihar) : Axiomatic structure of Minkowskian geometry. Bull pure appl Sci-Sect D 2007, 26(1), 53-7.

Main purpose is to aximomatize space time Geometry proposed by Minkowski which is applicable in establishing the Geometrical significance of Einstein's relativity theory. Derives the modified version of reversed triangle inequality which remains valid for infinite dimensional space as well. Mainly analyses the results due to H-Busemann.

8 ref

008910   Dharmadhikari J A;Dharmadhikari A K;Makhija V S;Mathur D (NO, Tata Institute of Fundamental Research, 1, Homi Bhabha Road, Mumbai-400 005, Email: atmo11@tifr.res.in) : Multiple optical traps with a single laser beam using a simple and inexpensive mechanical element. Curr Sci 2007, 93(9), 1265-70.

Ordinary wire mesh is utilized to facilitate the creation of multiple optical traps (tweezers) for maniªpulation of small micron or sub-micron particles. Each of the traps formed in this manner is continuous and the entire array is amenable to easy control. The method is simple to implement, inexpensive, and obviates the need to timeshare a laser beam among a set of positions, as is required in conventional multiple traps. Quantify the utility of the method by demonstrating that the continuous multiple traps are of essentially uniform strength. By way of illustrating the utility of the multiple traps, a single live red blood cell (RBC) of diameter <126>-8 μm was held at two locations on its surface; upon varying the inter-trap spacing, distortion in cell shape provides a ready means of studying the elastic properties of the RBC membrane under physiological conditions.

7 illus, 32 ref

008909   Dewangan P;Ramprasad T;Ramana M V (NO, National Institute of Oceanography, Goa-403 004, Email: pdewangan@nio.org ) : Finite differene modelling of scattered hydrates and its implications in gas-hydrate exploration. Curr Sci 2007, 93(9), 1287-90.

Gas-hydrates have drawn considerable attention in the scientific community due to their importance as an alternative energy source. One of the best tools for hydrate exploration is conventional 2D reflection seiªsmics, which records the base of the hydrate stability zone manifested in the form of a bottom-simulating reflector (BSR). The conventional seismic data depict BSR as a continuous layer and this can be misleading in the mapping and prediction of reserves, while high frequency seismic and drilling data collected worldªwide have shown gas-hydrates to be scattered deposits. Investigates the seismic response of scattered hydrates with varying frequencies and shown that BSR amplitudes in 2D seismics can be misleading if the size of the Fresnel zone is larger than the distance between the scatterers.

4 illus, 13 ref

008908   Datta B;Das B (Computer Centre, North Bengal Univ, (W.B.)) : Thermal stress due to variable temperature distribution on the surface of a prestressed elastic solid. Indian J Theor Phys 2008, 54(3), 249-62.

Concerned with the determination of therm stresses in a semi-infinite elastic solid when small deformations due to steady temperature distributions have been superposed on a large deformation, the solid being initially stressed. The boundary surface is subjected to prescribed temperature distribution within a circular region, the rest being free from any such distribution. The cases for the hemispherical or paraboloidal temperature distribution are considered and numerical results are deduced in both eases.]

1 illus, 8 ref

008907   Das K K (NO, , 34, Talbagan East Road, Nonachandanpukur, Barrackpore, Kolkata-700 122, Email: kanak-11@yahoo.co.in) : Study of flow of dusty visco-elastic conducting fluid through porous medium. Indian J Theor Phys 2008, 54(2), 145-63.

Attempt has been made to investigate the flow of visco-elastic Rivlin-Ericksen fluid starting from rest subjected to time-dependent pressure gradient applied at the free surface. The analytical solution for velocity profiles of the fluid and the dust particles have been found out by using Laplace transform method. Finally the effects due to magnetic field, mass concentration of dust particles are discussed with the help of graphs and tables. ]

4 illus, 5 tables, 12 ref

008906   Chaudhari H C;Shinde V J (Microwave Research Centre, P.G. Physics Dep, J.E.S. College, Jalna-431 203, Email: hcchaudhari@rediffmail.com) : Moisture dependent dielectric study of different soil textures at X-band microwave frequency. Bull pure appl Sci-Sect D 2007, 26(1), 17-23.

Interaction of electromagnetic waves with the materials of planet earth provides the information for microwave remote sensing. The dielectric properties of material are function of its chemical constituents such as carbon, calcium carbonate, salinity and physical properties such as porosity, density and temperature. Measurements of real (ε') and imaginary (ε'') parts of the complex dielectric constant (ε*) of different soil textures with varied moisture content were made at X-band microwave frequency. Infinite sample method is used for these measurements. The value of ε'and ε'' first increases slowly and then increase rapidly with moisture content. From these measurements, the a.c. conductivity and relaxation time are also reported. The result shows the change in electrical properties of dry and moisture-laden soils. The effect of soil textures is also observed. The precise microwave dielectric measurements of soils and recognition of their dependence on physical and chemical composition are interesting and can be used in support of radar investigations of the Earth's geology.

2 tables, 22 ref

008905   Chakraborty S;Chanda P K (NO, Central Drugs Laboratoryp, 3 Kyd Street, Kolkata-700 016, , Email: susa_chak@yahoo.com) : Painleve test for integrability for a combination of Yang's self-dual equations for SU(2) gauge fields and Charap's equations for chiral invariant model of pion dynamics and a comparative discussion among the three. Pramana J Phys 2007, 68(4), 535-45.

Painleve test for integrability for the combined equations generated from Yang's self-dual equations for SU(2) gauge fields and Charap's equations for chiral invariant model of pion dynamics faces some peculiar situations that allow none of the stages (leading order analysis, resonance calculation and checking of the existence of the requisite number of arbitrary functions) to be conclusive. It is also revealed from a comparative study with the previous results that the existence of abnormal behaviour at any of the stated stages may have a correlation with the existence of chaotic property or some other properties that do not correspond to solitonic behaviour.

1 table, 11 ref

008904   Chakraborty B (Research and Development Div, , Mecon Limited, Ranchi, Jharkhand-834 002, Email: drchakraborty_biswajit@yahoo.com) : Comparison of line spread obtained in a confocal microscopic setup with a conventional video microscope. IETE J Res 2007, 53(4), 339-46.

Confocal microscopy is a special technique in the field of optical microscopy.with wide applications in the areas of surface micro structuring of metal and non-metal surfaces, finger print observations in forensic sciences, 3D volume rendering of biological specimen etc. The main feature of confocal microscope is higher lateral as well as higher axial resolution. The higher axial resolution of confocal microscope gives rise to optical slicing capability. In the present paper the line spread function (LSF) is evaluated with the help of edge spread function (ESF) obtained through point scanning of an edge object in a reflection mode confocal microscopic setup. The spread of the LSF is also evaluated from the edge image obtained through a conventional transmission mode microscope fitted with a video camera. The comparison of LSF spread yields an estimation of improvement in lateral resolution in a confocal microscopic setup.

6 illus, 16 ref

008903   Bordalai J P;Duorah H L (Solid State Physics Lab, , Lucknow Road, Timarpur, PO Delhi-110 054, Email: jpbdli@yahoo.co.in) : EM fields and radiation resistance due to a loop type of antenna in a conductive medium. IETE J Res 2007, 53(4), 347-53.

Electromagnetic (EM) fields and radiated power from a small loop type antenna in a conductive (lossy) medium in VLF and LF ranges are studied theoretically. The derived field equations can also be used for free space, by applying proper simplification to the expression for the propagation constant. The equations are valid for the values the ratio of antenna radius to nearest field point distance equal to or less than 0.1 and the radius of the antenna to be equal to or less than 2 /1r| where | gamma | is the magnitude of the propagation constant in a conductive medium. Validation of the derived equations is shown by use of Maxwell's equations and by comparison of the simplified expressions for free space by another method.

3 illus, 11 ref

008902   Bayhan H;Ozden S (Physics Dep, Faculty of Art and Science, Mugla Univ, 48000 Mugla, Turkey, Email: hbayhan@mu.edu.tr) : Frequency dependence of junction capacitance of BPW34 and BPW41 p-i-n photodiodes. Pramana J Phys 2007, 68(4), 701-6.

Investigates the frequency dependence of small-signal capacitance of silicon BPW34 and BPW41 (Vishay) p-i-n photodiodes. We show that the capacitance-frequency characteristics of these photodiodes are well-described by the Schibli and Milnes model. The activation energy and the concentration of the dominant trap levels detected in BPW34 and BPW41 are 280-330 meV and 1.lxl0¹²-1.2xl0¹² cm^-3, respectively. According to the high-frequency C-V measurements, the impurity concentrations are determined to be about 5.3xl0¹² and 1.9xl0¹³cm^-3 in BPW41 and BPW34, respectively using the method of ΔV/Δ(C^-2) vs. C.

3 illus, 8 ref

008901   Basu M;Das B R (Mathematics Dep, Jadavpur Univ, Kolkata-700 032, Email: bikasranjandas@yahoo.com) : Annular punch on a semi-infinite transversely isotropic elastic medium. Indian J Theor Phys 2008, 54(2), 117-28.

Considers a steady-state isothermal elastic problem of a transversely isotropic semi-infinite medium when an axisymmetric annular punch bounded by two concentric circles is pressed against its free surface. The normal component of displacement is calculated in the punch-free region. It is shown graphically. The corresponding stress distribution may be calculated. The stress intensity factors are also calculated. ]

1 illus, 3 ref

008900   Ahuja B L;Heda N L (Physics Dep, College of Science Univ, M.L. Sukhadia Univ, Udaipur-313 001, Email: blahuja@yahoo.com) : On a low intensity <. Pramana J Phys 2007, 68(5), 843-50.

A new design and construction of a low intensity (100 mCi)²⁴¹ Amγ "/-ray Compton spectrometer is presented. The planar spectrometer is based on a small disc source with the shortest geometry. Measurement of the momentum density of polycrystalline AI is used to evaluate the performance of the new design. The measured profile is in good agreement with the existing theoretical data and our density functional calculations.

5 illus, 1 table, 14 ref

008086   Yadav B S;Yadav A K;Seema;Subhash Chand (Molecular Spetroscopy and Biophysics laboratory, D.N.College, Meerut-250 002) : Electronic spectral studies of 2-chloro-6-methylpyridine in various solvents. Indian J Phys 2007, 81(3), 395-401.

The electronic transition bands of 2-chloro-6-methyl pyridine molecule in liquid state and the effect of <65>-halogen atom on the absorption intensity of the S-band (characteristic band of aromatic ring) have been studied.The n-π* transition (E2-band) has shown the usual behavior towards the substitution and the polarity of the solvents. But the n-π* transition (R-band) has evidenced a usual behavior towards the solvent polarity (i.e. the n-π* transition has shown blue shift with respect to the n-π* system of pyridine). The halogen atom and/or orhto para directing group (having high potential for a large inductive effect) have shown a marked influence on the sp<^>2 electrons of the N-atom of the ring. As a result, the 8-band has evidenced an unusual behavior i.e. it has not showna hyperchromic effect with increase in the polarity of the solvent.