004155   Sinha R R;Nandi T K (Physics Dep, J.J.S. College, S.K. Univ, Mihijam, Dumka, Bihar) : Determination of cosmogenic radionuclide <. Acta Cienc Indica-Phys 2008, 34(2), 207-11.

In the study an attempt has been made to detect ³⁶Cl. Which is the most optimum rare element from the quartz sample of the plateau region of Jharkhand. Using the Pelletron energies for AMS study, beam of CI, P and Si are detected by MAGIC detector.

3 illus, 1 table, 5 ref

004154   Singh V P;Saroha D;Gopal G;Singh S;Jha R K; Bajaj M M (Physics Dep, D.J. College, Baraut-250 611) : Impact of BIS processes on universal networking. Acta Cienc Indica-Phys 2008, 34(2), 333-9.

The prime objective of the present investigation is to examine, comprehend and exploit the universal connectivity and the role of BIS processes in creating long range perturbations on the cosmic scale. We have used quantum field theory to calculate the cross-sections of various cosmic events (long range effects). We also show that it is possible to preserve this universal networking by our focussed and well thought out activities. By mitigating the BIS processes, it is possible to elongate the life span of universal networking and exploit it for global advantages of all the living creatures. Also shown that the cosmic networking involves cosmic strings. These strings are affected by BIS field created on the earth by human beings. Closed strings are seriously impaired by the BIS entropy.

1 illus

004153   Singh S N;Thakur A K;Singh A K (Post Graduate Dep of Physics, C.M. Science College, Darbhanga) : Characteristics study of compact dielectric resonator loaded patch antenna. Acta Cienc Indica-Phys 2008, 34(2), 299-302.

Now-a-days, Portable devices have become one of the necessary appliances for daily lives. To conveniently carry these portable devices (such as cell phones media players etc.), it is necessary to design them in compact form. They should also have light weight but these models should not be at the cost of their performance. The challenge to implement such small devices is to mount all the necessary circuits on to a small highly integrated transceiver unit. Among all the components, the antenna is one of the most challenging to scale down in size because the size of the conventional antenna depends on the operation frequency of required applications. In the present paper, step has been taken towards the reduction of size of antenna. For this purpose, compact dielectric resonator loaded with patch antenna has been presented to enhance the bandwidth. A foam layer has been used between metallic patch and the dielectric resonator. The simulation technique has been employed to measure the radiation patterns and return loss. A good agreement is found between the simulated & measured results.

4 illus, 4 ref

004152   Singh R S (Physics Dep, Faculty of Science, Jai Narain Vyas Univ, Jodhpur-342 005) : Transport properties of B.C.C. transition metals : using a pseudopotential approach. Acta Cienc Indica-Phys 2008, 34(2), 253-6.

The transport properties of transition metals (V, Nb, Ta, Cr, Mo and W) have been investigated using the pseudopotential approach (tight binding approach and effective mass correction approach). The formalism includes the effect of d-bands explicitly. The results thus obtained show a good agreement with the available experimental data.

1 table, 11 ref

004151   Singh B P;Ritu;Ashok Kumar;Kumar K N;Sharma K S (Physics Dep, T.M. Bhagalpur Univ, Bhagalpur-812 007) : Structure and electrical resistivity of AIGa liquid alloys. Acta Cienc Indica-Phys 2008, 34(2), 199-206.

The evaluation of the electrical resistivity of binary alloys, requires the true knowledge of the partial structure factors as well as the form factor of the constituent species. Partial structure factors are measurable, in principle, but the practical difficulties are severe and it is not promising to use the measured data. Therefore, we have considered a simple theoretical approach based on hard sphere reference system and the Percus-Yevick equation to compute the partial structure factor. The concentration dependence of the hard sphere parameters are obtained by minimizing the Helmholtz free energy of the system following the Gibbs-Bogoliubov variational technique. We have used it to compute the concentration dependence of electrical resistivity of AIGa liquid alloys. Our study reveals that the unlike particle correlation contributes positively to the absolute value of electrical resistivity while unlike particle correlation makes a negative contribution. The calculated values with H-S exchange (at C₁ = C₂ = 0.5, 36, 17 mΩ cm) is in close agreement with the experimental value 34.45 mΩ cm.

2 illus, 2 tables, 15 ref

004150   Samal D;Anil Kumar P S (Physics Dep, Indian Institute of Science, Bangalore-560 012, Email: debphy@physics.iisc.ernet.in) : Giant magnetoresistance, nobel prize in physics 2007. Resonance 2008, 13(4), 343-54.

The 2007 Nobel Prize in Physics was awarded to Albert Fert and Peter Griinberg for the discovery of giant magnetoresis-tance (GMR). GMR is achieved in metallic multilayers, where the resistance of the multilayer changes considerably by the application of a magnetic field. This has paved the way for high density data storage in magnetic media.

5 illus, 11 ref

004149   Roy A K;Yadav S;Roy S K (Univ Dep of Physics, L.N. Mithila Univ, Darbhanga-846 004) : Analysis of electromagnetic scattering by bodies of revolution with wires. Acta Cienc Indica-Phys 2008, 34(2), 321-4.

Electromagnetic scattering from composite bodies that consist of conducting objects in an important and challenging problem in the field of computational electromagnetics. The goal in this paper, the scattering of an arbitrary plane wave by a body of revolution (BOR) with multiple attached wires has been calculated by the method of moments (MoM). Numerical results for monochromatic plane wave scattering by smooth and nonsmooth axis symmetric objects, including spheres, cone-spheres and finite cylinders have been compared with results from the literature, illustrating the accuracy and computational efficiency associated with the use of properly constructed spectral methods. We compute plane wave scattering and find satisfactory agreement with method of moment (MoM) computations.

2 illus, 4 ref

004148   Ranganath G S (NO, , 422, 10th Cross, 8th Main padmanabhanagar, Bangalore-560 070, Email: gs.ranganath@gmail.com) : Black-body radiation. Resonance 2008, 13(2), 115-33.

Towards the end of the nineteenth century, it became clear that within the frame work of classical physics, it was not possible to understand the phenomenon of Black-Body Radiation. In 1900 Max Planck came up with a theory that at one stroke accounted successfully for all its observed features. This theory has been presented against a backdrop of the major discoveries that led to it.

2 illus, 10 ref

004147   Preeti Singh;Shiv Singh;Anil Kumar (Physics Dep, Hindu College, Moradabad, Uttar Pradesh) : Orthogonal and band-limited wavelet packets. Acta Cienc Indica-Phys 2008, 34(2), 219-24.

Orthogonal wavelet packets are used to further decompose wavelet components. A Wavelet packet is said to be band-limited if the support of it, is contained in a finite interval. Some estimates to characterize orthogonal and band-limited wavelet packets with refer to Lebesgue spaces are discussed.

12 ref

004146   Prajapati S S;Singh S P;Mishra S P (NO, , Prabha Puram, Pusauli, Behind D.A.V. School, Robertsganj, Sonebhadra-231 216) : H.C.P. metals about their phonon dispersion relation. Mendel int J 2007, 24(1-2), 61-2.

A simple pseudopotential approach is used to study the lattice dynamics of such metals following the analysis of Brovman and Kagan. The proposed theory is found to be adequate for studying the physical properties of H.C.P. metal viz. Zn and present theoretical model explains the measured data on thephonon dispersion relation of zinc satisfactorily.

1 illus, 9 ref

004145   Prajapati S S;Singh S P (NO, , Prabha Puram, Pusauli, Behind D.A.V. School, Robertsganj, Sonebhadra-231 216) : Vibrational properities of H.C.P. metals. Mendel int J 2007, 24(1-2), 57-8.

A theoretical model is used to study the vibrational properties of h.c.p. metals in conjuction with general tensor forces for taking into account the non pair interaction. The proposed theory is found to be adequate for explaining the vibrational properties of h.c.p. metals. The calculated vibrational properties of Cadmium show a satisfactory agreement with the experimental data.

2 illus, 2 tables, 6 ref

004144   Padmanabhan T (IUCAA, Post Bag 4, Pune Univ, Dean, Core Academic Programmes Campus, Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in) : Snippets of physics, 3. quantum mechanics on the run. Resonance 2008, 13(3), 212-17.

How does one study quantum mechanics in an accelerated frame? The answer to this question leads to some surprising insights into the solutions of the Schrodinger equation for harmonic oscillator!

1 ref

004143   Padmanabhan T (NO, , IUCAA, Post Bag 4, Pune Univ, Dean, Core Academic Programmes Campus, Ganeshkhind, Pune-411 007, Email: paddy@iuca.ernet.in) : Snippets of physics, 2. Angular momentum of electromagnetic field. Resonance 2008, 13(2), 108-14.

Eletromagnetic fields carry not only energy and momentum but also angular momentum. The angular momentum of the field can lead to some curious results like the one which is described here.

1 illus, 2 ref

004142   Padmanabhan T (NO, Pune University, Dean, Core Academic programmes Campus Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in) : Snippets of physics, 4. Schwarzschild metric at a discounted price. Resonance 2008, 13(4), 312-18.

The gravitational field of a massive, spherical, body like the Sun is described in general relativity by a solution to Einstein's equations called the Schwarzschild soution. Here is an elementary persepective on this solution, which - though far from a rigourous derivation -- raises intriguing questions.

1 illus, 2 ref

004141   Narendra Kumar;Sanyal G S (NO, Raman Research Institute, Bangalore-560 080, Email: nkumar@rri.res.in) : Characterization of radiation as an electromagnetic wave or a particle - a criterion. Proc Indian Natn Sci Acad 2008, 74(1), 19-20.

The wave-particle duality of radiation from a source in the electromagnetic spectrum is well-known. A criterion is proposed to determine when the radiation will predominantly exhibit the properties of a particle and when will it behave as a wave. An experiment is suggested to validate the criterion.

1 illus, 5 ref

004140   Moses Kennedy S M (Physics Dep, Sri. Sivasubramaniya Nadar College of Engineering, Rajiv Gandhi Salai, Kalavakkam-603 110) : Luminescence studies of γ-irradiated CaF₂:Dy:Pb:Na single crystals. Acta Cienc Indica-Phys 2008, 34(2), 281-9.

The optical absorption (OA) of un-irradiated crystal exhibited a strong peak around 6.48 eV attributed to the 'A band absorption of Pb²⁺ ions. The γ-irradiated crystal exhibited OA bands around 2.01, 3.18, 3.74 (shoulder, hereafter denoted as 'sh.'), 2.48 (sh.) and 6.22 eV. The first three bands could be attributed to MA or M_A⁺ (denoted as M_na) and the 2.48 eV band to the RA⁺ centre. Exciting the un-irradiated crystal around 5.79 ' eV yielded characteristic Dy³⁺ emission. The excitation spectrum for Dy³⁺ emission around 2.10 eV showed narrow bands, which were attributed to the 4f transitions of Oy³⁺ ions. Irradiated crystal exhibited a broad and intense excitation spectrum for the 2.10 eV emission. Exciting the irradiated crystal around 3.35 eV yielded emission at 1.75, 2.14 and 2.54 eV. The first band was from M_Na centre and the other two emission bands were due to Dy³⁺ ions. Also the formation of R_a⁺ centre and its emission around 2.23 eV was observed. An additional excitation band around 2.86 eV for the R_A⁺ centre emission was found. Sensitized luminescence of Dy³⁺ characteristic emission was observed before and after γ-irradiation.

5 illus, 31 ref

004139   Kar S (Physics and Centre for Theoretical Studies Dep, Indian Institute of Technology, Kharagpur-721 302, Email: sayan@phy.iitkgp.ernet.in) : Introduction to the raychaudhuri equations. Resonance 2008, 13(4), 319-33.

The Raychaudhuri equations are first introduced through simple examples and illustrations. Their use and the resulting consequences in cosmology are then briefly outlined.

3 illus, 4 ref

004138   Jha R K;Jha A (P.G. Dep of Physics, C.M. Science College, Darbhanga, Bihar) : Analysis of electromagnetic-wave diffraction by wedge with anisotropic impedance boundary conditions. Acta Cienc Indica-Phys 2008, 34(2), 245-51.

The diffraction of plane electromagnetic wave by a wedge with anisotropic impedance boundary conditions is analysed. The problem is formulated in terms of two components of electric and magnetic fields satisfying the Helmholtz-equation but are coupled through first order boundary conditions. The superposition of geometric waves and the wave diffracted by the apex of the wedge is represented in the solution.

2 illus, 7 ref

004137   Jaiswal R (NO, , Lucknow) : Concept and applications of quantum dots. Everymans Sci 2008, 63(3), 178-82.

The evolution over the last two decades of the nanocrystals are known as quantum dots. The growth of this revolutionary new tool from electronic materials science, involving marvelous innovations with limitless applications will enable use of this material across many industries to far-reaching biological applications. It will allow researchers to study cell processes at the level of a single molecule and may result in new and better ways to diagnose and treat cancers. Defines some of the technologies and usages related to quantum dots. Many key areas employing them are discussed with possible commercial applications/developments in future. The technologies are of immense practical use and have the potential to replace many conventional, inefficient processes. The key to the adoption of quantum dots is the continued reduction in cost of the application developed using it along with augmented output and efficiency.

3 ref

004136   Gupta J K P;Singh N K (Univ Dep of Physics, L.N.M. Univ, Darbhanga-846 004) : Analysis of the cross-polarization of a linearly polarized maximum gain antenna. Acta Cienc Indica-Phys 2008, 34(2), 263-5.

Using Ludwig's third definition, the cross-polarized field of maximum gain linearly polarized directional antenna is identically zero. This condition would not result from Ludwig's first or second definitions. We have also seen that the cross-polarized field of a circularly polarized maximum gain directional antenna is identically zero.

6 ref

004135   Geetha D;Ramesh P S;Panneerselvam A (Physics Dep, Annamalai Univ, Annamalainagar, Tamilnadu-608 002) : Ultrasonic studies on polymer blends in n-alcohols. Acta Cienc Indica-Phys 2008, 34(2), 213-17.

The velocities of ultrasound were studied for the solutions of polymer blends (NaCMC : PEG and MC : PEG) in lower alphatic alcohols. The frequency used was 3 MHz and the concentration (by molar) ranged from 0.01 to 0.09 in propanol, butanol and pentanol. Observations showed that the ultrasonic velocity increases with increasing concentration of polymer blend. From the experimental data the related acoustical parameters have been calculated and results are discussed in the light of complex formation present in the system.

6 tables, 8 ref

004134   Das D P;Thakur A K;Vinit Kumar;Pandey R K (Research Fellow, , Mogalpura, P.O. Lalbagh, Darbhanga) : Noise optimization in sc active networks. Acta Cienc Indica-Phys 2008, 34(2), 291-7.

The performance of most of the electronic circuits is limited due to noise generated by thermal fluctuations at higher frequencies. It is particularly important in SC networks widely used in CMOS integrated circuits. Although the theory of noise in SC networks is discussed in literature, it is very intricate (complicated). The numerical calculation of noise in SC networks is tedious. This paper represents the study of noise generated in MOS switch transistor as well as in operational amplifier in SC active networks. The noise resulting from a sampled data signal consists of a narrow band of the SC active networks. By introducing the ratio of under sampling, the noise contribution due to SC active network has been evaluated and it has been applied to SC integrator. A good concordance has been obtained.

7 illus, 6 ref

004133   Chaudhary P K;Jha G (Physics Dep, L.N. Mithila Univ, Darbhanga) : Determination of antenna gain by scattering cross-section measurements. Acta Cienc Indica-Phys 2008, 34(2), 315-19.

Theoretical determination of the gain of an antenna can be obtained by using a two-port network and geometrical interpretation of equations involving antenna scattering. As an alternative to this approach it is shown that the measurement procedures for gain can be developed from simple considerations of the receiving, transmitting and scattering properties of antennas. The main advantages of the technique are that no gain standard is required and a disturbing feedline to the antenna can be avoided. In addition to this the technique seems to be highly accurate.

2 illus, 8 ref

004132   Chaudhary A K;Jha A (P.G. Dep of Physics, C.M. Science College, Darbhanga) : Analysis of near to far field transformation based on Rao-Wilton-Glisson (RWG) basis function using surface equivalence theorem. Acta Cienc Indica-Phys 2008, 34(2), 185-92.

The RWG basis function is applied for the transformation of near to far field of two dimensional triangular grid. Here the surface equivalence theorem is applied and the equivalent current density, J_z in the TMz case or Mz in the TEEz case, on the radiation contour is interpolated. The interpolation is valid for the near to far field transformation in frequency domain. Numerical results in this domain is verified by comparison with analytical solution.

3 illus, 9 ref

004131   Chandra M;Singh N;Kumar V (Physics Dep, A.S.A. College, Mathura, Uttar Pradesh) : Effective role of electric field and ions in the formation of cloud. Acta Cienc Indica-Phys 2008, 34(2), 329-32.

There exists certain electric field in the atmosphere and also within the clouds. The electric field causes the lightning which accelerates the formation of the rains. The lightning causes the ionization of air in ions produced enhance the nucleation. So that the nucleation rate is increased. It has been shown that the rate of increase of radius of droplet is directly proportional to the electric field applied. We have calculated the increase of radius and the change in potential energy as the function of relaxation time.

26 ref

004130   Biswal S;Pattnaik B K (NO, , Divyadyuti, Debottar Colony, Nayagarh-752 069) : Commencement of MHD unsteady coueady couette flow of oldroyd fluid through two porous walls when the lower wall suddenly starts oscillating harmonically. Acta Cienc Indica-Phys 2008, 34(2), 303-13.

The study of MHD (magnetohydrodynamics) Couette flow problems has attracted the attention of many researchers in recent years owing to its technological importance. The effect of porosity of the medium on the flow has been ignored in many cases even though it influences the flow behaviour remarkably. Attempts have been made to study the combined effect of magnetic field and porosity on the unsteady Couette flow of Oldroyd fluid when the lower wall suddenly oscillates harmonically with a velocity A sin ω't' and the upper wall is assumed to be stationary. With the help of Galerkin technique, the approximate solutions for the velocity, temperature, shearing stress and rate of heat transfer are obtained. The effects of magnetic parameter, permeability factor, Prandtl number, elastic parameter, suction parameter, source parameter and Eckert number on the velocity and temperature field have been analysed, with the aid of graphs. The skin friction (shearing stress) and Nusselts number (rate of heat transfer) are studied from their values entered in tables. It is noticed that the combined effect of magnetic field and porosity modifies the flow behaviour significantly.

6 illus, 2 tables, 19 ref

004129   Bhattacharjee S;Baishya B (Physics Dep, Dibrugarh Univ, Dibrugarh-786 004) : Paraconductivity of thin films of Dy₂O₃, Eu₂O₃, and Pr₆O₁₁ substituted compounds. Acta Cienc Indica-Phys 2008, 34(2), 257-62.

Rare earth oxide substituted compounds have been prepared by reacting the powders of rare earth oxides, (RE)₂O₃, (where RE = Dy, Eu, Pr), Barium Carbonate (BaCO₃) and Cupric Oxide (CuO), by solid state reaction method at 950°C for 16 hours. The thin films have been deposited by high vacuum evaporation technique (vacuum ≈10^-6 torr). The variation of electrical resistivity (ρ) with temperature (7) from liquid nitrogen temperature (77K) to room temperature (300K), have been studied for all the three compounds. The superconducting transitions have been observed at temperatures 89 K, 87 K, and 90 K for Dy₂O₃, Eu₂O₃ and Pr₆O₁₁ substituted compounds respectively. Using Aslamasov-Larkin theory, the effects of super conducting order parameter fluctuations (SCOPF) in the three samples have been studied.

17 ref

004128   Arunagiri C;Seshadri S (Physics Dep, Government Arts College, Ariyalur-621 713) : Infrared vibration spectra of 8-hydroxy quinoline 3-hydrochloride. Acta Cienc Indica-Phys 2008, 34(2), 267-70.

The infrared vibrational spectra of 8-Hydroxy Quinoline 3-Hydrochloride has been recorded in the region 300-4000 cm^-1 using KBr pellet. The observed fundamental bands were assigned assuming the molecules under point group. These bands have been correlated with various modes of vibration reported in the literature.

2 illus, 1 table, 6 ref

004127   Agarwal V;Dwivedi A;Sharma B S (NO, B.S. Anangpuria Institute of Technology and Management, Faridabad, Haryana) : Generalized equation of state for MgO based on the Lennard-Jones potential. Acta Cienc Indica-Phys 2008, 34(2), 225-31.

An equation of state (EOS) has been formulated using the generalized Lennard-Jones potential so as to satisfy the Stacey criterion for B'∞, pressure derivative of bulk modulus at infinite pressure. The results for pressure, bulk modulus and its first pressure derivative have been obtained for the compressed (VIV₀ < 1) as well as the expanded (VIV₀ > 1) MgO. The results are compatible with the analysis of geophysical data, performed by Stacey and Davis, revealing B'_∞/B'₀ =3/5. The present EOS is found to behave satisfactorily in the compressed region as well as the expanded region.

5 illus, 15 ref

004126   Adarsha Kumar (NO, , Prof. Colony (Dighi West), P.O. Lalbagh, Darbhanga-846 004) : Analysis of the decomposition of electromagnetic fields in homogeneous space. Acta Cienc Indica-Phys 2008, 34(2), 193-7.

Here the guidelines on the metric coefficients have been derived in order for a three-dimensional electromagnetic field in a source free homogeneous space to be decomposed into transverse electric (TE) and transverse magnetic (TM) parts. The relationship between scalar and vector potentials and the equation satisfied by the vector potential component have been presented. Using the theory presented here it will be evident that why decomposition of fields can only be accomplished along certain axes in a given coordinate system.

1 table, 6 ref

002112   Umamaheswari U;Ajeetha N;Srinivas G;Ojha D P (Liquid Crystal Research Laboratory, Post-Graduate Dep of Physics, Andhra Loyola College, Vijayawada-520 008, Email: durga_ojha@hotmail.com) : Odd-even effects in homologous series of p-n-alkoxybenzoic acid: role of anisotropic pair potential. Bull pure appl Sci-Sect D 2008, 27(1), 55-64.

A quantum mechanical analysis has been carried out to determine the association energy of 6 first homologous of p-n-alkoxybenzoic acid series using Rayleigh-Schrodinger perturbation method for different nearest neighbour configurations of interacting pairs. The net atomic charges and dipoles have been computed using the CNDO/2 method. The complete association energy with all its components has been reported. An attempt has been made to correlate this energy with transition temperature and hence to understand the odd-even effect at molecular level.

8 illus, 15 ref

002111   Tiwari R K;Mishra G R (Circuit Design & Simulation Lab. Physics & Electronics Dep, Dr.R.M.L.Avadh Univ, Faizabad, Uttar Pradesh) : Comparative study of CMOS and BJT current mirror circuit. Bull pure appl Sci-Sect D 2008, 27(1), 47-53.

The current mirror circuits have wide application in integrated circuit design. They are used as current source and sink. The constant current source is used both in biasing & active load. Present paper focuses the comparative study of CMOS current mirror & BJT current mirror with their design methodologies. The proper selection of device model has been playing an important role in the design of current mirror. In this paper we have simulated the current mirror circuits using SPICE and optimized device parameter.

12 illus, 7 ref

002110   Sharma S K;Choudhury D K (NO, Institute of Advanced Study in Science and Technology, Guwahati-781 035, Email: sumita_sharma82@yahoo.com) : Pentaquarks and glueballs. Phys Educ 2007, 24(4), 267-75.

Evidence for a novel family of particles called pentaquarks, which contain four quarks and one antiquark, reported in 2003 has generated a huge amount of interest among physics communities. A further possibility is the existence of particles consisting solely of gluons called glueballs. Its shows theoretical and experimental status of these two exotics.

4 illus, 3 tables, 31 ref

002109   Sahoo S;Goswami M (Physics Dep, National Institute of Technology, Durgapur-713 209, Email: sukadevsahoo@yahoo.com) : Symmetries in physics. Phys Educ 2007, 24(4), 277-84.

Symmetry is a crucial concept in physics, mathematics, chemistry and biology. Its definition is also applicable to art, music, architecture and innumerable patterns designed by nature, in both animate and inanimate forms. According to H. Weyl "Symmetry, as wide or as narrow as you may define its meaning, is one idea by which man through ages has tried to comprehend and create order, beauty and perfection".

2 tables, 8 ref

002108   Rama Murthy G (NO, Internaional Institute of Information Technology(IIIT), Gachibowli, Hyderabad-500 032) : Transient evolution of universe. Int J Syst Cybernetics Inf 2007, (Apr), 11-13.

Astro-physicists proposed various equilibrium theories about the origin and evolution of universe. To account for experimental data, theories of expanding universe are proposed. The author proposes various novel ideas related to the transient evolution of universe. Based on the speculation of earlier physicists, the author proposes various ideas related to the notion of repulsive force between mass/energy sytems. This concept of repulsive force potentially provides one possible explanation for the recent experimental observation related to dark energy.

7 ref

002107   Rajamannan B;Balachandramohan M;Viruthagiri G (Physics Dep, Annamalai Univ, Annamalainagar-608 002) : Porosity measurments of some brick samples collected in Villupuram district of Tamil Nadu. Bull pure appl Sci-Sect D 2008, 27(1), 123-25.

The measurement of the porosity values by the method of water absorption reveals the quality of the brick used in building construction. The percentage of porosity values is used to identify the class of brick samples. An attempt is made to correlate the percentage of porosity with the strength of the brick.

1 table, 5 ref

002106   Parivathini K;Bakkialakshmi S (Physics Dep, Annamalai Univ, Annamalai Nagar-608 002, Email: Bakkialakshmi66@yahoo.com ) : Spectroscopic study on fluorescence quenching of pyrene by N,N-dimethylaniline (DMA) in sodium dodecyl sulfate (SDS). Bull pure appl Sci-Sect D 2008, 27(1), 85-94.

Electronically excited molecules can be deactivated in bimolecular collisions with added quenching molecule, the spectroscopic study on fluorescence quenching of pyrene by N, N-Dimethylaniline (DMA) in sodium dodecyl sulfate (SDS) have been made by time resolved techniques. The fluorescence quenching analysis reveals the binding of DMA with the micelles. The absorption and fluorescence spectra of pyrene with various quencher and surfactant concentrations were recorded successfully. The Stern - Volmer constant (Ksv) and the regression coefficient (r) have been evaluated from the plot. The Stern-Volmer plots for the quenching of pyrene by DMA is found to be linear and the constants (Ksv) depend on the micellar concentration. From the spectroscopic study it was observed that the Stern - Volmer plots are in linear and the regression analysis of the curves are in good correlation. The fluorescence quenching of pyrene is dynamic in nature. The important physico- chemical constants such as ionization potential, electron affinity, Stoke's shift and solvent parameter have also been evaluated from the plots.

7 illus, 2 tables, 15 ref

002105   Pandey S B;Yadav R S;Kumar V (Electronics Science Dep, B.R.A.B.U., Muzaffarpur, Bihar) : Ensemble monte carlo simulations for the study of band structure of wide band gap materials. Bull pure appl Sci-Sect D 2008, 27(1), 145-48.

Ensemble Monte Carlo simulations were performed to study band structure in bulk materials, especially in the high field region. All relevant scattering mechanisms including impact ionization were used, in the case of zinc sulphide, the use of exchange formalism with a local density approximation band structure for simulations of electron transport has led to modified results for the drift velocity and the average energy. The average energy shows a strong increase above 50kv/m and 80 kv/cm. This behavior originates from the occupation of the neighboring valleys, which starts above 100 kv/m. The derived drift velocity is similar.

2 illus, 7 ref

002104   Pandey S B (Univ Dep of Electronic Science, B.R.A.B.U., Muzaffarpur, Bihar) : Electron transmission through an impurtiy in a quantum wire. Bull pure appl Sci-Sect D 2008, 27(1), 133-38.

Electron transmission through an impurity in quantum wire is strongly affected by the applied magnetic fields and the shape of the cross section. When the magnetic field entered along the small axis of cross section, electron transmission is strongly enhanced since the overlap between incident and reflected wave functions become smaller and back scattering is decreased. When the magnetic field entered along the large axis of the cross section, the overlap between wave functions become larger, backward scattering is enhanced and transmission is suppressed. The position of the quasi band states move towards lower energy values. The conductance strengths of magnetic fields decreases this is due to the decrease of the number of conducting channels upon increasing the strength of the applied magnetic field. As the cross sectional shape becomes symmetric switching of the conductance to different conductance levels occurs. This is due to the shifting of the energy levels towards higher values resulting in a smaller number of contributing conducting channels to the conductance. In the case of small axis of the cross section the shifting of levels towards higher energy values becomes larger, resulting in a smaller number of open sub bands and smaller conductance values. The transmission through an impurity in asymmetric wires is greatly enhanced when the magnetic field is present. The transmission through an impurity in asymmetric wires is greatly suppressed when the magnetic field is applied along the large axis of the cross section and the influence of the magnetic field on the transmission is weaker.

2 illus, 11 ref

002103   Padmanabhan T (IUCAA, Post Bag 4, Pune Univ Dean, Core Academic Programmes Campus, Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in) : Snippets of physics, potentials of potatoes: a surprise in newtonian gravity. Resonance 2008, 13(1), 4-11.

It is well known in Newtonian gravity that a spherically symmetric density distribution produces a force outside it which falls as the square of the distance. Surprisingly, the converse is not true! Just because the force falls as inverse square outside a density distribution, you cannot conclude that it must be spherically symmetric. Explores this and related issues.

2 illus, 2 ref

002102   Narasimha D;Chitre S M (NO, Tata Institute of Fundamental Research, Mumbai-400 005, Email: kumarchitre@gmail.com) : Gravitational lens systems to probe extragalactic magnetic fields. Curr Sci 2007, 93(11), 1506-13.

The Faraday rotation measurements of multiply-imaged gravitational lens systems can be effectively used to probe the existence of large-scale ordered magnetic fields in lensing galaxies and galaxy clusters. The available sample of lens systems appears to suggest the presence of a coherent large-scale magnetic field in giant elliptical galaxies, somewhat similar to the spiral galaxies.

1 illus, 1 table, 46 ref

002101   Lo C Y (NO, Applied and Pure Research Institute, 17 Newcastle Drive, Nashua, NH 03060 USA) : Deflection of light to second order and invalidity of Einstein's "principle of covariance". Bull pure appl Sci-Sect D 2008, 27(1), 1-15.

It has been shown that deflection of light to second order, expressed in the "impact parameter" b. are the same tor different gauges having the same frame of reterence. However, it is found that to measure ''b", it must be measured in terms of closest distances "d". Thus, "b" is actually different for different gauges if the issue of measurement is considered. In fact, this second order is related to finding the correct physical gauge, and thus is a difficult problem. Moreover, not every result obtained can be expressed as mathematically gauge invariant. For instance, the "event of horizon" for different gauges with the same frame of reference can be arbitrary constants. In conclusion, the notion of gauge invariant measurable quantity is a mathematical illusion because such a quantity, as shown, is actually gauge dependent when the measurement is involved, and thus just as Einstein's "covariance principle" is due to an inadequate ability to distinguish the difference between mathematics and physics.

46 ref

002100   Khaparde R B;Puthiyadan S;Pradhan H C (Homi Bhabha Centre for Science Education, Tata Institute of Fundamental Research, V.N. Purav Marg, Mankhurd, Mumbai-400 088, Email: rajeshkhaparde@gmail.com) : Reflection of polarized light. Phys Educ 2007, 24(4), 289-99.

For an undergraduate optics laboratory on the study of reflection of light emitted by a laser source from the surface of a transparent prism. In this experiment an analyzer is used to study the state of polarization and a photo-detector for measuring the intensity of the reflected light. The transmission axis of the analyzer is first determined using Malus's law and the input-output characteristics of the photo-detector are studied. Then study the variation of reflectivity with the angle of incidence for the plane-polarized light with plane of vibration first parallel and then perpendicular to the plane of incidence. The refractive index of the material of the prism is determined using Brewster's law.

7 illus, 6 ref

002099   Katti V R;Thyagarajan K;Shankara K N;Kiran Kumar A S (NO, ISRO Satellite Centre, PB No 1795, Vimanapura Post, Bangalore-560 017, Email: vrkatti@isac.gov.in) : Spacecraft technology. Curr Sci 2007, 93(12), 1715-36.

This paper presents a summary of the efforts at ISRO for the development of spacecraft technology over the past three decades and also outlines technological trends for the evolution of communication space platforms, as well as scientific and remote sensing satellite systems. Tracing the developmental efforts since Aryabhatta, the first Indian satellite, through the experimental phase of application-oriented remote sensing and communication satellites namely Bhaskara-I, Bhaskara-II and Apple, the state-of-art operational INSAT and IRS series of satellites are presented. The communication satellite platforms namely I-1K, I-2K, I-3K and I-4K with lift off masses in the range of one to four tonnes, power generation capabilities of 1 kW to 10 kW and more, meeting multifarious requirements of telecommunication, telecasting, DTH (Direct to Home TV) multimedia applications and meteorological services have been developed. The improvements derived from the usage of multijunction solar cells, lithium-ion batteries and other mass optimization techniques are passed on for larger payload compliment and longer life. Technological trends in the design of communication payloads and the advancements in key elements such as antennas, microwave power amplifiers and receive systems as well as spacecraft mainframe are dis-cussed. Commercialization of developmental efforts in the form of design, building and commissioning of communication satellites for the international service providers arc highlighted in brief.

5 tables, 18 ref

002098   Joshi A N;Joshi P A (Physics Arts Dep, Science and Commerce College, Rahuri-431 705) : Laser induced changes in structural and electrical properties of CdSe thin films. Bull pure appl Sci-Sect D 2008, 27(1), 23-35.

The synthesis of CdSe films via electrochemical route discussed in detail. In this, deposition potential for deposition of CdSe was found. All the preparative parameters such as current density and thickness measurement are optimized. These films are used for various characterisations such as XRD, surface morphology and electrical properties. CdSe Thin films have been successfully synthesized using an electrodeposition technique. Electrodeposition provides control over CdSe stoicheometry at room temperature. The electrical and structural properties have been studied. The study of laser excited changes in I-V characteristics of Ag/CdSe junction, it has been observed that there was increase in charge carrier concentration across the junction and hence the conductivity of CdSe was found to be increased as the excitation period increases. Silver substrate seems to be suitable for the junction formation. Photo excitation by laser of CdSe junctions was found to be significant.

10 illus, 9 ref

002097   Jha A K;Jha A;Jha H K (Physics Dep, R.M. College, Saharsa, Bihar) : Inverse scattering for homogeneous dielectric cylinder. Bull pure appl Sci-Sect D 2008, 27(1), 139-44.

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

002096   Herndon J M (NO, , 11044 Red Rock Drive, Transdyne Corporation, San Diego, CA 92131, USA, Email: mherndon@san.rr.com) : Nuclear georeactor generation of the earth's geomagnetic field. Curr Sci 2007, 93(11), 1485-7.

2 illus, 1 table, 24 ref

002095   Giridhar G;Rangacharyulu M;Ravikumar R V S S N;Rao P S (Physics Dep, Acharya Nagarjuna Univ, Nagarjuna Nagar-522 510) : Spectroscopic studies on Vo(II) ion doped in mixed alkali cadmium phosphate glasses. Bull pure appl Sci-Sect D 2008, 27(1), 106-14.

Optical and EPR studies of VO(II) ions doped mixed alkali cadmium phosphate (LiNaCdP) glasses are carried out at room temperature. Three samples with varying concentrations x Li₂O + (20-x) Na₂O + 20 CdO + 59.5 P₂O₅ + 0.5 V₂O₅ (5 ≤ x ≤ 15) have been prepared. The Spin-Hamiltonian parameters obtained from room temperature EPR spectra of VO(II) ions doped glasses. These results indicate that the dopant VO(II) ion enters the glass matrix into a tetragonally compressed octahedral site. The bonding parameters evaluated by correlating optical and EPR data suggest that bonding between the central metal ion and ligands is partially covalent. The values of (g_⊥ -g_<95>l) are 0.0518, 0.0489 and 0.0548 for LiNaCdP1 glass, LiNaCdP2 glass and LiNaCdP3 glass respectively. It indicates the tetragonal distortion is more in LiNaCdP3 glass. The optical absorption spectra also suggest the same. For LiNaCdP2 glass the tetragonal distortion is less when compared to other two glasses, i.e at equal composition of alkali content (x=10) in the glass sample. From this, we can conclude that mixed alkali effect can be clearly established in the lithium-sodium cadmium phosphate glasses under study.

3 illus, 1 table, 43 ref

002094   Dhanujana Chari V;Suresh Y;Chunduru V (Physics Dep, Sidhartha College for Women, Hyderabad, Email: vardhani_c2001@yahoo.co.in) : Birefringence near the surface and interior of an Y-cut type LiTaO₃ optical waveguide. Bull pure appl Sci-Sect D 2008, 27(1), 128-31.

The field of integrated optics is primarily based on the fact that light can be guided and coupled in very thin films of transparent materials on suitable substrates. Due to the miniature size of integrated optical devices. it is possible to obtain high density of optical components in space, unlike the case in bulk optics. In addition the confinement of light energy in small regions of space leads also to an efficient interaction of the acoustic wave, thus leading to much more efficient acoustic optic modulators requiring very low drive powers. In characterizing the integrated optical devices, the refractive index is an important parameter and understanding of this parameter from atomic point of view is very essential. Since the refractive index is due to dipole moments of the ions it can be expressed in terms of polarizabilities of the constituent ions and "Local" fields at the site of the ions.

3 illus, 2 tables, 2 ref

002093   Deb B M;Sadhukhan M;Sinha S S;Sengupta S; Biswas R (NO, Indian Institute of Science Education & Reseacrh, HC-VII, Sector III, Salt Lake, Kolkata-700 106, Email: bmdeb@yahoo.co.in) : Integrated and open-ended experiment study of chemical waves in time and space. Resonance 2008, 13(1), 54-80.

Discusses an exciting experiment in non-linear dynamics. This provided an imaginative platform for bringing in chemical, physical, biological, mathematical and computational sciences together. There are implications for earth sciences as well.