009516   Subramanian V (Microwave Laboratory, Physics Dep, Indian Institute of Technology Madras, Chennai-600 036, Email: manianvs@iitm.ac.in) : Microstrip microwave band gap structures. Pramana J Phys 2008, 70(4), 739-46.

Microwave band gap structures exhibit certain stop band characteristics based on the periodicity, impedance contrast and effective refractive index contrast. These structures though formed in one-, two- and three-dimensional periodicity, are huge in size. In this paper, microstrip-based microwave band gap structures are formed by removing the substrate material in a periodic manner. This paper also demonstrates that these structures can serve as a non-destructive characterization tool for materials, a duplexor and frequency selective coupler. The paper presents both experimental results and theoretical simulation based on a commercially available finite element methodology for comparison.

7 illus, 7 ref

009515   Singh J S (Physics Dep, Anand Engineering College, Keetham, Agra-282 007, Email: jssaec@rediffmail.com) : Laser Raman and infra-red spectra of biomolecule: 5-aminouracil. Pramana J Phys 2008, 70(3), 479-86.

Laser Raman (200-4000 cm^-1) and IR (200-4000 cm^-1) spectra of 5-aminouracil were recorded in the region 200-4000 cm^-1. Assuming a planar geometry and C_s point group symmetry, it has been possible to assign all the 36 (25α' + 11α") normal modes of vibration for the first time. The two NH bonds of the NH2 group appear to be equivalent as the NH₂ stretching frequencies satisfy the empirical relation proposed for the two equivalent NH bonds of the NH2 group. The two NH2 stretching frequencies are distinctly separated from the CH/NH ring stretching frequencies. A strong and sharp IR band at 3360 cm^-1 could be identified as the anti-symmetric NH2 mode whereas the band at 3290 cm^-1 with smaller density could be identified as the symmetric NH2 stretching mode. All other bands have also been assigned different fundamentals/overtones/combinations.

2 tables, 50 ref

009514   Shrimali M D;Sinha S;Aihara K (Aihara Complexity Modelling Project, ERATO, JST, Tokyo 151 0064, Japan, Email: m.shrimali@gmail.com) : Asynchronous updating of threshold-coupled chaotic neurons. Pramana J Phys 2008, 70(6), 1127-34.

Studies a network of chaotic model neurons incorporating threshold-activated coupling. We obtain a wide range of spatiotemporal patterns under varying degrees of asynchronicity in the evolution of the neuronal components. For instance, we find that sequential updating of threshold-coupled chaotic neurons can yield dynamical switching of the individual neurons between two states. So varying the asynchronicity in the updating scheme can serve as a control mechanism to extract different responses, and this can have possible applications in computation and information processing.

5 illus, 13 ref

009513   Sharma P K;Rao S L;Mishra K;Trivedi R G;Bora D (NO, Institute for Plasma Research, Bhat, Gandhinagar-382 428, Email: pramod@ipr.res.in) : Characteristics of electron cyclotron resonance plasma formed by lower hybrid current drive grill antenna. Pramana J Phys 2008, 70(3), 503-16.

A 3.7 GHz system, which is meant for LHCD experiments on ADITYA tokamak, is used for producing ECR discharge. The ECR discharge is produced by setting the appropriate resonance magnetic field of 0.13 T, with hydrogen at a fill pressure of about 5 x 10^-5 Torr. The RF power, up to 10 kW (of which ~50% is reflected back), with a typical pulse length of 50 ms, is injected into the vacuum chamber of the ADITYA tokamak by a LHCD grill antenna and is used for plasma formation. The average coupled RF power density (the RF power/a typical volume of the plasma) is estimated to be ~5 kW/m³. When the ECR appears inside the tokamak chamber for the given pumping frequency (f = 3.7 GHz) a plasma with a density (n_e) ~ 4 x 10¹⁶ m^-3 and electron temperature ~8 eV is produced. The density and temperature during the RF pulse are measured by sets of Langmuir probes, located toroidally, on either side of the antenna. H_α signals are also monitored to detect ionization. An estimate of density and temperature based on simple theoretical calculation agrees well with our experimental measurements. The plasma produced by the above mechanism is further used to characterize the ECR-assisted low voltage Ohmic start-up discharges. During this part of the experiments, Ohmic plasma is formed using capacitor banks. The plasma loop voltage is gradually decreased, till the discharge ceases to form. The same is repeated in the presence of ECR-formed plasma (RF pre-ionization), formed 10 ms prior to the loop voltage. We have observed that (with LHCD-induced) ECR-assisted Ohmic start-up discharges is reliably and repeatedly obtained with reduced loop voltage requirement and breakdown time decreases substantially. The current ramp-up rates also decrease with reduced loop voltage operation. These studies established that ECR plasma formed with LHCD system exhibits similar characteristics as reported earlier by dedicated ECR systems. This experiment also addresses the issue of whether ECR plasma formed with grill antenna exhibits similar behavior as that formed by single waveguide ECR antenna. Our experimental observations suggest that the characteristics of (LHCD system-induced) ECR-assisted Ohmic start-up discharges show similar properties, reported earlier with normal ECR-assisted Ohmic start-up discharges and hence LHCD system may be used as ECR system at reduced toroidal magnetic field for other applications like wall conditioning.

7 illus, 1 table, 32 ref

009512   Sharma A K;Chhachhia D P;Mahajan C G;Aggarwal A K (Coherent Optics Div, Central Scientific Instruments Organisation, Sector 30, Chandigarh-160 030, Email: aka1945@rediffmail.com ) : Dual beam encoded extended fractional Fourier transform security hologram with in-built repositioning. Pramana J Phys 2008, 70(1), 131-9.

Describes a simple method for making dual beam encoded extended fractional Fourier transform (EFRT) security holograms. The hologram possesses different stages of encoding so that security features are concealed and remain invisible to the counterfeiter. These concealed and encoded anticounterfeit security features in the security hologram can only be read through a key hologram. Key hologram also facilitates in-built repositioning of security hologram. The method of fabrication, the principle of reconstruction and the experimental results are presented.

5 illus, 13 ref

009511   Shaikh A M (Solid State Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: shaikham@.barc.gov.in) : Development of neutron detectors and neutron radiography at Bhabha atomic research centre. Pramana J Phys 2008, 71(4), 663-72.

Design and development of neutron detectors and R&D work in neutron radiography (NR) for non-destructive evaluation are important parts of the neutron beam and allied research programme of Solid State Physics Division (SSPD) of Bhabha Atomic Research Centre (BARC). The detectors fabricated in the division not only meet the in-house requirement of neutron spectrometers but also the need of other divisions in BARC, Department of Atomic Energy units and some universities and research institutes in India and abroad for a variety of applications. The NR facility set up by SSPD at Apsara reactor has been used for a variety of applications in nuclear, aerospace, defense and metallurgical industries. The work done in the development of neutron detectors and neutron radiography is reported in this article.

12 illus, 2 tables, 11 ref

009510   Sayed F;Mamun A A (Physics Dep, Jahangirnagar Univ, Savar, Dhaka-1342, Bangladesh, Email: shilpee_36@yahoo.com) : Effect of ion-fluid temperature on dust-ion-acoustic solitons. Pramana J Phys 2008, 70(3), 527-33.

The properties of dust-ion-acoustic (DIA) solitons in an unmagnetized dusty plasma, whose constituents are adiabatic ion-fluid, Boltzmann electrons, and static dust particles, are investigated by employing the reductive perturbation method. The Korteweg-de Vries equation is derived and its stationary solution is numerically analyzed. The parametric regimes for the existence of positive and negative solitons are found. It has been shown that ion-fluid temperature not only significantly modifies the basic features (width and amplitude) of DIA solitons, but also introduces some new features of DIA solitons.

4 illus, 14 ref

009509   Satpathy L;Patra S K;Choudhury R K (NO, Institute of Physics, Bhubaneswar-751 005, Email: rkc@barc.gov.in) : Fission decay properties of ultra neutron-rich uranium isotopes. Pramana J Phys 2008, 70(1), 87-99.

The fission decay of highly neutron-rich uranium isotopes is investigated which shows interesting new features in the barrier properties and neutron emission characteristics in the fission process. ^{233U and 235U are the nuclei in the actinide region in the beta stability valley which are thermally fissile and have been mainly used in reactors for power generation. The possibility of occurrence of thermally fissile members in the chain of neutron-rich uranium isotopes is examined here. The neutron number N = 162 or 164 has been predicted to be magic in numerous theoretical studies carried out over the years. The series of uranium isotopes around it with N = 154-172 are identified to be thermally fissile on the basis of the fission barrier and neutron separation energy systematics; a manifestation of the close shell nature of N = 162 (or 164). We consider here the thermal neutron fission of a typical representative 249U nucleus in the highly neutron-rich region. Semiempirical study of fission barrier height and width shows that 250U nucleus is stable against spontaneous fission due to increase in barrier width arising out of excess neutrons. On the basis of the calculation of the probability of fragment mass yields and the microscopic study in relativistic mean field theory, this nucleus is shown to undergo exotic decay mode of thermal neutron fission (multi-fragmentation fission) whereby a number of prompt scission neutrons are expected to be simultaneously released along with the two heavy fission fragments. Such properties will have important implications in stellar evolution involving r-process nucleosynthesis.}

5 illus, 1 table, 35 ref

009508   Sarkar P;Dey B J (Physics Dep, Pune Univ, Pune-411 007, Email: bdey@physics.unipune.ernet.in) : Intrinsic localized modes and nonlinear impurity modes in curved fermi-pasta-ulam chain. Pramana J Phys 2008, 70(6), 1023-9.

Explores the nature of intrinsic localized modes (ILMs) in a curved Fermi-Pasta-Ulam (FPU) chain and the effects of geometry and second-neighbor interaction on the localization and movability properties of such modes. We determine analytically the structure of the localized modes induced by an isotopic light-mass impurity in this chain. We further demonstrate that a nonlinear impurity mode may be treated as a bound state of an ILM with the impurity.

4 illus, 18 ref

009507   Saravanan R;Sayed Ali K S;Israel S (Physics Dep, The Madura College, Madurai-625 011, Email: saragow@dataone.in) : Electron density distribution in Si and Ge using multipole, maximum entropy method and pair distribution function analysis. Pramana J Phys 2008, 70(4), 679-96.

The local, average and electronic structure of the semiconducting materials Si and Ge has been studied using multipole, maximum entropy method (MEM) and pair distribution function (PDF) analyses, using X-ray powder data. The covalent nature of ing and the interaction between the atoms are clearly revealed by the two-dimensional i maps plotted on (1 0 0) and (110) planes and one-dimensional density along [1 0 0], [1 1 0] and [1 1 1] directions. The mid-bond electron densities between the atoms are 0.554 e/Angustrum^{33 for Si and Ge respectively. In this work, the local structural information has also been obtained by analyzing the atomic pair distribution function. An attempt has been made in the present work to utilize the X-ray powder data sets to the structure and electron density distribution using the currently available versatile methods, MEM, multipole analysis and determination of pair distribution function for these two systems.}

9 illus, 8 tables, 41 ref

009506   Santhosh Kumar S (Physics Dep, Mahatma Gandhi Government Arts College, Chalakkara, Mahe-673 311, Email: santhosh.physics@gmail.com) : Level density and shape changes in excited SD shell nuclei. Pramana J Phys 2008, 71(1), 175-80.

In the calculation authors have used the Monte Carlo method of generating collective spin and total energy of the nucleus for various configurations of the system with N₀ single particle states available for n number of particles. The different configurations (arrangements of occupied single particle states) leading to a particular energy E and spin J are then collected to get the density of states for the given energy E and spin J. We find that if we use the cranked Nilsson model single particle states for the rotational frequency Ω = 0.0 hw, 0.05 hw and 0.1 hw there is a shift in the maximum density of states W_max with a tendency for the system to become more oblate or prolate depending on the shift in the maximum density of states as the angular momentum decreases or increases. The change in nuclear level density with collectivity, i.e. with the use of cranked Nilsson model single particle levels has been noticed.

27 ref

009505   Saikia B;Anil Kumar (Physics Dep, Icfai Tech., ICFAI Univ, P.O. Kamalghat, Agartala-799 210, Email: bulumoni_saikia@rediffmail.com) : Effect of normal processes on thermal conductivity of germanium, silicon and diamond. Pramana J Phys 2008, 71(1), 143-55.

The effect of normal scattering processes is considered to redistribute the phonon momentum in (a) the same phonon branch - KK-S model and (b) between different phonon branches - KK-H model. Simplified thermal conductivity relations are used to estimate the thermal conductivity of germanium, silicon and diamond with natural isotopes and highly enriched isotopes. It is observed that the consideration of the normal scattering processes involving different phonon branches gives better results for the temperature dependence of the thermal conductivity of germanium, silicon and diamond with natural and highly enriched isotopes. Also, the estimation of the lattice thermal conductivity of germanium and silicon for these models with the consideration of quadratic form of frequency dependences of phonon wave vector leads to the conclusion that the splitting of longitudinal and transverse phonon modes, as suggested by Holland, is not an essential requirement to explain the entire temperature dependence of lattice thermal conductivity whereas KK-H model gives a better estimation of the thermal conductivity without the splitting of the acoustic phonon modes due to the dispersive nature of the phonon dispersion curves.

5 illus, 2 tables, 13 ref

009504   Sahu B;Satpathy L (Physics Dep, North Orissa Univ, Takatpur, Baripada-757 003, Email: bd_sahu@yahoo.com) : Resonance states in <. Pramana J Phys 2008, 70(5), 847-62.

The resonance states in ^{16O+16O, 12C+16O, α+16O and α+12C are described using modified Morse potential proposed earlier whose success has already been demonstrated in the case of 12C+12C system. The general validity of such a potential with long range, shallow depth and repulsive soft core determined from the resonance data itself is being examined through the present study of the resonances in the above four systems. In each system, the experimental data of a large number of states have been successfully described with a modified Morse potential. The success points out a common mechanism of the origin of these states, and reaffirms authentically the diatomic-like rotational and vibrational picture of the nuclear molecular resonances proposed previously. The close resemblance between the physics of diatomic molecules and nuclear molecular resonances extending to the level of potential which is Morse type in both the cases - although belong to two different areas of physics - is further strengthened through the present study.}

13 illus, 23 ref

009503   Sahu B;Sahu B;Agarwalla S K (Physics Dep, North Orisa Univ, Baripada-757 003, Email: bd_sahu@yahoo.com) : Evalution of eigenvalues of a smooth potential via Schroedinger transmission across multi-step potential. Pramana J Phys 2008, 70(1), 27-39.

In a one-dimensional quanta! solution of Schroedinger equation, the general expressions for reflection and transmission coefficients are derived for a potential constituting n number of rectangular wells and barriers. These expressions are readily used for the estimation of eigenvalues of a smooth potential which is simulated by a multi-step potential. The applicability of this method is demonstrated with success in potentials with different forms including the most versatile Ginocchio potential where the widely used numerical method like Runge-Kutta integration algorithm fails to yield the result. Accurate evaluation of eigenvalues free from numerical problem for any form of potentials, whether analytically solvable or not, is the highlight of the present multi-step approximation method in the theory of potential scattering.

3 illus, 9 ref

009502   Sahoo S;Dutta K;Acharyya S;Sit S K (Instrumentation Technology Dep, Saha Institute of Technology, P.O. Debhog, Purba, Email: swapansit@yahoo.co.in) : Dielectric relaxation of binary polar liquid mixture measured in benzene at 10 Ghz frequency. Pramana J Phys 2008, 70(3), 543-52.

The dielectric relaxation times τjk 'S and dipole moments μjk 's of the binary (jk) polar liquid mixture of N,N-dimethyl acetamide (DMA) and acetone (Ac) dissolved in benzene (i) are estimated from the measured real σ'ijk and imaginary α"ijk parts of complex high frequency conductivity σ*ijk of the solution for different weight fractions wjk's of 0.0, 0.3, 0.5, 0.7 and 1.0 mole fractions xj of Ac and temperatures (25, 30, 35 and 40°C) respectively under 9.88 GHz electric field. τjk's are obtained from the ratio of slopes of σ"ijk-wjk and σ'ijk-wjk curves at wjk → 0 as well as linear slope of σ"ijk-σ'ijk curves of the existing method (Murthy et al, 1989) in order to eliminate polar-polar interaction in the latter case. The calculated r's are in excellent agreement with the reported T'S due to Gopalakrishna's method. μjk's are also estimated from slopes β's of total conductivity σijk-wjk curves at wjk → 0 and the values agree well with the reported μ's from G.K. method. The variation of τjk's and μ-jk's with xj of Ac reveals that solute-solute molecular association occurs within 0.0-0.3xj of Ac beyond which solute-solvent molecular association is predicted. The theoretical dipole moments μtheo's are calculated from bond angles and bond moments to have exact μ's only to show the presence of inductive, mesomeric and electromeric effects in the substituent polar groups. The thermodynamic energy parameters are estimated from In(τjkT) against 1/T linear curve from Eyring's rate theory to know the molecular dynamics of the system and to establish the fact that the mixture obeys the Debye-Smyth relaxation mechanism.

8 illus, 15 ref

009501   Sahoo A;Sarkar S;Krishna P S R;Bhagat V (Physics Dep, Jadavpur Univ, Kolkata-700 032, Email: rnjoarder@yahoo.co.in ) : Molecular conformation and structural correlations of liquid D-1-propanol through neutron diffraction. Pramana J Phys 2008, 71(1), 133-41.

An analysis of neutron diffraction data of liquid deuterated 1-propanol at room temperature to extract its molecular conformation is presented. Being a big molecule with twelve atomic sites, the analysis is tricky and needs careful consideration. The resulting molecular parameters are compared with electron diffraction (gas phase), X-ray diffraction (liquid phase) and MD simulation results. Information about the hydrogen-bonded intermolecular structure in liquid is extracted and nature of the probable molecular association suggested.

4 illus, 15 ref

009500   Sahni V;Srivastava D P;Satsangi P S (NO, Dayalbagh Educational Institute (Deemed Univ), Dayalbagh, Agra) : Unified modelling theory for qubit representation using quantum field graph models. J Indian Inst Sci 2009, 89(3), 351-62.

Linear graph theory, a branch of topology, has been applied to such diverse systems as ranging from electrical networks through real physical systems and "conceptual" socio-economic-environmental systems to "esoteric" creational systems. Linear graph theory represents one step towards a systems modelling discipline which coordinates various branches of knowledge into one scientific order. This paper presents a quantum field graph model which is facilitated by considering a qubit as a basic building block and representing it through an appropriate linear graph. The system graph is in two separate parts corresponding to a qubit representation (Iψ-) = α|0<209> + β|1<209>), consisting of "ket 0" and "ket 1" subsystem graphs. Unit "Poynting"-like vectors |0> and |1) behave like quantum across (potential) variables specifying "direction" of information (data)/energy propagation, as it were, while a and β behave like quantum through (flow-rate or "force") variables specifying probability parameters for quanta of information (data)/energy flow-rate (energy flux or power flow, W/m^{2). For n independent states, there will be precisely n basis quantum potential vectors (or unit "Poynting" vectors). The model has been successfully applied for several quantum gates as well as applications such as quantum teleportation and has the potential for successfully modelling systems at the high end of complexity scale.}

^iia10 illus, 9 ref

009499   Rout G C;Ojha M S;Behera S N (Condensed Matter Physics Group, Government Science College, Chatrapur-761 020, Email: gcr@iopb.res.in) : Superconducting gap anomaly in heavy fermion systems. Pramana J Phys 2008, 70(4), 711-30.

The heavy fermion system (HFS) is described by the periodic Anderson model (PAM), treating the Coulomb correlation between the f-electrons in the mean-field Hartree-Fock approximation. Superconductivity is introduced by a BCS-type pairing term among the conduction electrons. Within this approximation the equation for the superconducting gap is derived, which depends on the effective position of the energy level of the f-electrons relative to the Fermi level. The latter in turn depends on the occupation probability n^{f of the f-electrons. The gap equation is solved self-consistently with the equation for nf; and their temperature dependences are studied for different positions of the bare f-electron energy level, with respect to the Fermi level. The dependence of the superconducting gap on the hybridization leads to a re-entrant behaviour with increasing strength. The induced pairing between the f-electrons and the pairing of mixed conduction and f-electrons due to hybridization are also determined. The temperature dependence of the hybridization parameter, which characterizes the number of electrons with mixed character and represents the number of heavy electrons is studied. This number is shown to be small. The quasi-particle density of states (DOS) shows the existence of a pseudo-gap due to superconductivity and the signature of a hybridization gap at the Fermi level. For the choice of the model parameters, the DOS shows that the HFS is a metal and undergoes a transition to the gap-less superconducting state.}

14 illus, 17 ref

009498   Roshenkranz S;Osborn R (Materials Science Div, Argonne National Lab, Argonne, IL 60439, USA, Email: srosenkranz@anl.gov) : Corelli : efficent single crystal diffraction with elastic discrimination. Pramana J Phys 2008, 71(4), 705-11.

Single crystal diffuse scattering provides one of the most powerful probes of short-range correlations on the 1-100 nm scale, which often are responsible for the extreme field response of many emerging phenomena of great interest. Accurate modeling of such complex disorder from diffuse scattering data however puts stringent experimental demands, requiring measurements over large volumes of reciprocal space with sufficient momentum and energy resolution. Here, we discuss the potential of the cross-correlation technique for efficient measurement of single crystal diffuse scattering with energy discrimination, as will be implemented in a novel instrument, Corelli. Utilizing full experiment simulations, we show that this technique readily leads up to a fifty-fold gain in efficiency, as compared to traditional methods, for measuring single crystal diffuse scattering over volumes of reciprocal space with elastic discrimination.

4 illus, 17 ref

009497   Richter D;Biehl R;Monkenbusch M;Hoffmann B; Merkel R (Institut fur Festkorperforschung, Institut fur Bio-und Nanosysteme, Forschungszentrum, Julich, D-52425 Julich, Germany, Email: d.richter@fz-juelich.de) : Polymer dynamics from synthetic polymers to proteins. Pramana J Phys 2008, 71(4), 729-38.

Starting from the standard model of polymer motion - the Rouse model -we briefly present some key experimental results on the mesoscopic dynamics of polymer systems. We touch the role of topological confinement as expressed in the reptation model and discuss in some more detail processes limiting the confinement. In the second part we relate to some new developments concerning the measurement of large-scale internal dynamics of proteins by neutron spin echo.

8 illus, 22 ref

009496   Ravindran R (NO, Atria Institute of Technology, Bangalore-560 024, Email: renrav@math.iisc.ernet.in) : Equations governing kepler's laws of planetary motion. Resonance 2009, 14(12), 1166-70.

2 illus

009495   Rauch H (Atominstitut der Oesterreichischen Universitaeten, 1020 Wien, Austria, Email: rauch@ati.ac.at) : Non-classical neutron beams for fundamental and Solid state research. Pramana J Phys 2008, 71(4), 785-96.

The curious dual nature of the neutron, sometimes a particle, sometimes a wave, is wonderfully manifested in the various non-local interference and quantum contex-tuality effects observed in neutron interferometry. Non-classical states may become useful for novel fundamental and solid state research. Here we discuss unavoidable quantum losses as they appear in neutron phase-echo and spin rotation experiments and we show how entanglement effects in a single particle system demonstrate quantum contextuality. In all cases of interactions, parasitic beams are produced which cannot be recombined completely with the original beam. This means that a complete reconstruction of the original state would, in principle, be impossible which causes a kind of intrinsic irre-versibility. Even small interaction potentials can have huge effects when they are applied in quantum Zeno-like experiments. Recently, it has been shown that an entanglement between external and internal degrees of freedom exists even in single particle systems. This contextuality phenomenon also shows that a quantum system carries much more information than usually extracted. The path towards advanced neutron quantum optics will be discussed.

9 illus, 55 ref

009494   Rajaguru S P (NO, Indian Institute of Astrophysics, Sarjapur Road, Bangalore-560 034, Email: rajaguru@iiap.res.in) : Evershed effect as we understant in today. Resonance 2009, 14(11), 1040-46.

Following a description of the Evershed effect as observed by John Evershed in 1909 at the Kodaikanal Solar Observatory, we discuss the evolution of our scientific understanding that accompanied the development of the subject of magnetohy-drodynamics (MHD). How the modern telescopic observations as well as the computational capabilities are serving to uncover the complex magnetohydrodynamic processes behind this highly dynamical phenomenon is discussed at length.

3 illus, 16 ref

009493   Raj Kumar;Kaura S K;Chhachhia D P;Mohan D (Coherent Optics Div, Central Scientific Instruments Organisation, Sector 30, Chandigarh-160 030, Email: aka1945@rediffmail.com) : Comparative study of different schlieren diffraction of elements. Pramana J Phys 2008, 70(1), 121-9.

Presents an analysis of diffraction effects taking place at different Schlieren diffracting elements. Two types of diffraction effects are prominent in the Schilieren schemes. One is diffraction of direct light (source image) at the Schlieren element, which limits the sensitivity and resolution of Schlieren systems. The second type is the diffraction of light deflected from the test object at the Schlieren-diffracting element. This second type of diffraction degrades the quality of Schlieren results. Experimental results showing the effect of diffraction of light deflected from the test object at a phase knife-edge, corner of a square phase aperture and an optical fiber tip as Schlieren diffracting elements have been presented and discussed.

5 illus, 1 table, 12 ref

009492   Proffen T (Los Alamos National Laboratory, Lujan Neutron Scattering Center, Mailstop H805, Los Alamos, NM 87585, USA, Email: tproffen@lanl.gov) : Total neutron scattering : the key to the local and medium range structure of complex materials. Pramana J Phys 2008, 71(4), 713-9.

Structural characterization is mainly based on the measurement of Bragg intensities and yields the average structure of crystalline materials. The total scattering pattern, however, contains structural information over all length scales, and it can be used to obtain a complete structural picture of complex materials. Suddenly one has access to a new parameter, the real-space range of the refinement and structures can be analysed as a function of length scale straightforwardly.

4 illus, 12 ref

009491   Pintschovius L;Weber F;Reichardt W;Kreyssig A;Heid R;Reznik D;Stockert O;Hradil K (Forschungszentrum Karlsruhe, Institut fur Festkorperphysik, Postfach 3640, D-76021 Karlsruhe, Germany, Email: pini@ifpfzk.de) : Phonon linewidths in YNi₂B₂C. Pramana J Phys 2008, 71(4), 687-93.

Phonons in a metal interact with conduction electrons which give rise to a finite linewidth. In the normal state, this leads to a Lorentzian shape of the phonon line. Density functional theory is able to predict the phonon linewidths as a function of wave vector for each branch of the phonon dispersion. An experimental verification of such predictions is feasible only for compounds with very strong electron-phonon coupling. YN2B2C was chosen as a test example because it is a conventional superconductor with a fairly high T_c (15.2 K). Inelastic neutron scattering experiments did largely confirm the theoretical predictions. Moreover, they revealed a strong temperature dependence of the linewidths of some phonons with particularly strong electron-phonon coupling which can as yet only qualitatively be accounted for by theory. For such phonons, marked changes of the phonon frequencies and linewidths were observed from room temperature down to 15 K. Further changes were observed on entering into the superconducting state. These changes can, however, not be described simply by a change of the phonon linewidth.

6 illus, 10 ref

009490   Philip J (Sophisticated Test and Instrumentation Center, Cochin Science and Technology Univ, Cochin-682 022, Email: jp@cusat.ac.in) : Chasing light for five centuries : mission still continues. Sci Soc 2009, 6(1), 7-17.

Efforts of mankind to understand light started nearly 500 years ago, but our mission is not yet complete. Systematic studies to understand the wonderful phenomenon of light, through which we see everything around us, started with the famous corpuscular theory of light by Newton. It went through several revolutionary paths and ideas such as the wave theory, electromagnetic theory and Quantum theory and saw many marvelous experimental findings such as the laser. We continue to understand light better and better, but it is still far from complete. Several Nobel prizes have been awarded to discoveries and inventions related to light. The 2005 Nobel Prize in Physics was awarded to development of quantum optics and precision measurements based on the frequency combing technique. Briefly overviews these developments in a historical perspective and outlines the discoveries that led to the 2005 Nobel Prize in Physics.

8 illus, 2 ref

009489   Petrov A G;Naydenova S (NO, Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria) : Soft matter biosensors: stochastic and deterministic membrane sensing. J Indian Inst Sci 2009, 89(2), 195-209.

The concept of bilayer lipid membrane sensing is elaborated. Disposable bilayer lipid membrane sensors permit both stochastic and deterministic sensing regimes. Detection of cyano-bacterial toxins in waters by means of a stochastic sensing (ion channel induction) reveals a signature for a particular toxin type. Flexoelectricity of membranes provides a way of deterministic sensing. Detection of environmental pollution of waters by heavy metal ions (Cd^{++ and Hg++) is thereby rendered possible.}

24 illus, 44 ref

009488   Perez G (Departamento de Fisica Aplicada, Centro de Investigacion y de Estudios Avanzados, del Instituto Polite, Unidad Merida, Apartado Postal 73 "Cordemex", 97310 Merida, Yucatan, Mexico, Email: gperez@mda.cinvestav.mx) : Numerical simulations in granular matter: the discharge of a 2D silo. Pramana J Phys 2008, 70(6), 989-1007.

Gives a short and elementary review of numerical simulations in granular assemblies, giving the process of discharge of a 2D silo as an example. The strengths and limitations of different approaches are discussed, together with some comments on the specific issues related to the numerics of discontinuous dissipative collisions.

7 illus, 59 ref

009487   Pedraza-Morales M I;Rosado A;Salazar H (Instituto de Fisica, BUAP. Apdo., Postal J-48, C.P. 72570 Puebla, Pue., Mexico, Email: rosado@sirio.ifuap.buap.mx) : Effects of charged higgs bosons in the deep inelastic process ν_τN → T<. Pramana J Phys 2008, 70(4), 603-15.

Study the deep inelastic process ν_τ + N → τ + X (with N = (η + p)/2 an isoscalar nucleon), in the context of the two-Higgs doublet model Type II (2HDM(II)). We discuss the contribution to the total cross-section of diagrams, in which a charged Higgs boson is exchanged. We present results which show strong dependence of such contributions on tan β and M_H±. We show that for tan β ≈ 150 and M_H± 300 GeV, the contribution of the charged Higgs boson exchange diagrams to the cross-section of the charged current inclusive ν_τN collision can become important. We find that this contribution for an inclusive dispersion generated through the collision of an ultra-high-energy tau-neutrino with E_ν ≈ 10²¹ eV on a target nucleon can be as large as 40% of the value of the contribution of the W^± exchange diagrams, provided M_H± ≈ 300 GeV and tan β ≈ 150. Such enhancement and the induced variation on the mean inelasticity (y)^CC could lead to sizeable effects in the acceptance of cosmic tau-neutrino detectors at experiments such as HiRes, PAO, and the CRTNT, which are anchored to the ground, and at experiments such as EUSO and OWL, which are proposed to orbit around the Earth. We also compare the contribution to σ^tot_H+ from the different allowed initial quarks and we show that the contribution from the bottom quark dominates by far. This means that the H^± contribution practically always gives a top quark in. the final state. Such a large component of the cross-section having a top quark event in the final state could have recognizable features in the EAS experiments.

5 illus, 1 table, 41 ref

009486   Pecora L M (Code 6362, Naval Research Laboratory, Washington, DC 20375, USA, Email: pecora@anvil.nrl.navy.mil) : Synchronization of oscillators in complex networks. Pramana J Phys 2008, 70(6), 1175-98.

Theory of identical or complete synchronization of identical oscillators in arbitrary networks is introduced. In addition, several graph theory concepts and results that augment the synchronization theory and a tie in closely to random, semirandom, and regular networks are introduced. Combined theories are used to explore and compare three types of semirandom networks for their efficacy in synchronizing oscillators. It is shown that the simplest fc-cycle augmented by a few random edges or links are the most efficient network that will guarantee good synchronization.

13 illus, 14 ref

009485   Paul M K;Bora D (NO, Institute for Plasma Research, Bhat, Gandhinagar-382 428, Email: mkpaul@ipr.res.in) : Langmuir probe study in the nonresonant current drive regime of helicon discharge. Pramana J Phys 2008, 71(1), 117-31.

Characterization of the current drive regime is done for helicon wave-generated plasma in a torus, at a very high operating frequency. A radiofrequency-compensated Langmuir probe is designed and used for the measurement of plasma parameters along with the electron energy distributions in radial scans of the plasma. The electron energy distribution patterns obtained in the operational regime suggest that Landau damping cannot be responsible for the efficient helicon discharge in the present study. A typical peaked radial density profile, high plasma temperature and absence of an appreciable amount of energetic electrons for resonant wave-particle interactions, suggest that the chosen operational regime is suitable for the study of nonresonant current drive by helicon wave. Successful and significant current drive achieved in our device clearly demonstrates the capability of nonresonant current drive by helicon waves in the present operational regime.

10 illus, 26 ref

009484   Pati A K;Braunstein S L (NO, Institute of Physics, Bhubaneswar-751 005, Email: akpati@iopb.res.in) : Role of entanglement in quantum computation. J Indian Inst Sci 2009, 89(3), 295-302.

Quantum computers are believed to surpass their classical counterparts in speed-up and efficiency. However, the origin of this speed-up in quantum algorithms is not yet fully understood. There are indications that entanglement plays an important role in quantum computation. Quantum algorithms that do not involve entanglement appear to require an exponential amount of resources and may be efficiently simulated on a classical computer. Here we discuss the role of entanglement in quantum computation. As an illustration, we consider Grover's algorithm and how entanglement arises in this case. We will show that even though entanglement is present throughout the computation, the change of entanglement per iteration is exponentially small for large databases.

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009483   Pathak N P;Basu A;Koul S K (Electronics and Computer Engineering Dep, Indian Institute of Technology Roorkee, Roorkee-247 667, Email: skkoul@care.iitd.ernet.in) : Full wave analysis of non-radiative dielectric waveguide modulator for the determination of electrical equivalent circuit. Pramana J Phys 2008, 71(1), 65-75.

Reports the determination of electrical equivalent circuit of ON/OFF modulator in non-radiative dielectric (NRD) guide configurations at Ka-band. Schottky barrier mixer diode is used to realize this modulator and its characteristics are determined experimentally using vector network analyzer. Full wave FEM simulator HFSS is used to determine an equivalent circuit for the mounted diode and modulator in ON and OFF states. This equivalent circuit is used to qualitatively explain the experimental characteristics of modulator.

11 illus, 11 ref

009482   Patel B;Rai A K;Vinod kumar P C (Physics Dep, Sardar Patel Univ, Vallabh Vidyanagar-388 120, Email: azadpatel2003@yahoo.co.in) : Heavy flavor baryons in hypercentral model. Pramana J Phys 2008, 70(5), 797-804.

Heavy flavor baryons containing single and double charm (beauty) quarks with light flavor combinations are studied using the hypercentral description of the three-body problem. The confinement potential is assumed as hypercentral Coulomb plus power potential with power index ν. The ground state masses of the heavy flavor, J^{P = 1/2+ and 3/2+ baryons are computed for different power indices, ν starting from 0.5 to 2.0. The predicted masses are found to attain a saturated value in each case of quark combinations beyond the power index ν = 1.0.}

2 illus, 4 tables, 26 ref

009481   Panigarhi P K;Mitra C (NO, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur Campus, P.O. BCKV Campus Main Office, Mohanpur-741 252, Email: pprasanta@iiserkol.ac.in) : Use of quantum correlation: a theoretical and experimental perspective. J Indian Inst Sci 2009, 89(3), 333-50.

Recent interest in the field of quantum information processing has given rise to a flurry of theoretical as well as experimental activity, on entanglement, a purely quantum mechanical phenomenon. Author briefly review quantification of entanglement and its use in carrying out quantum tasks like teleportation. The measures are primarily concerned with bipartite entanglement. Systems such as spin chains and quantum dots have been identified to execute some of these quantum protocols. Experimental realization of quantum networks, especially in the form of spin chains, has been dealt here, along with methods to extract the content of entanglement from experimental data. We explicate the effect of environment on quantum networks and how to extract quantum information before the system decoheres.

^iia4 illus, 1 table, 77 ref

009480   Pandhija S;Rai A K (Laser Spectroscopy Research Laboratory, Physics Dep, Allahabad Univ, Allahabad-211 002, Email: awadheshkrai@rediffmail.com) : Laser-induced breakdown spectroscopy: a versatile tool for monitoring traces in materials. Pramana J Phys 2008, 70(3), 553-63.

Laser-induced breakdown spectroscopy (LIBS) is an emerging technique for simultaneous multi-elemental analysis of solids, liquids and gases with minute or no sample preparation and thus revolutionized the area of on-line analysis technologies. The foundation for LIBS is a solid state, short-pulsed laser that is focused on a sample to generate a high-temperature plasma, and the emitted radiation from the excited atomic and ionic fragments produced within the plasma is characteristic of the elemental composition of the sample that can be detected and analyzed using a suitable optical spectrograph. In the present paper, the applicability of LIBS for different solid samples having homogeneous (silver ornament, aluminum plate) or heterogeneous composition (soil) using nanosecond laser pulses is discussed. Nanosecond pulse laser makes plasma at the sample surface even at very low pulse energies and also allows for precise ablation of the substrate material with little damage to the surrounding area. We have also studied the penetration of different heavy metals inside the soil surface.

9 illus, 1 table, 16 ref

009479   Pandey M B;Dhar R (Physics Dep, Allahabad Univ, Allahabad-211 002, Email: dr.ravindra_dhar@hotmail.com) : Electrical properties of frustrated twisted grain boundary phases of liquid crystalline materials. J Indian Inst Sci 2009, 89(2), 147-67.

An overview of characteristics physical properties of twisted grain boundary (TGB) phases shown by some of the chiral liquid crystalline materials is given. After a brief discussion of various liquid crystalline phases, structure of various types of TGB phases, their general behaviour along with optical textures and some other characteristics have been discussed. Finally, details about dielectric behaviour of TGB phases with static and dynamic measuring electric field are reported and discussed.

23 illus, 1 table, 111 ref

009478   Pal P B (Palash B Pal, Saha Institute of Nuclear Physics, 1/AF Bidhan-Nagar, Kolkata-700 064, Email: pbpal@theory.saha.ernet.in) : At the root of things. Resonance 2009, 14(6), 544-67.

Modern theory of fundamental interactions describe strong, electromagnetic and weak interactions as quantum field theories with certain kinds of embedded internal symmetries called 'gauge symmetries'. Introduces quantum field theories and gauge symmetries to the uninitiated.

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009477   Padmanabhan T (IUCAA, , Pune Univ Campus, Post Bag 4, Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in ) : Snippets of physics, Kepler and his problem. Resonance 2009, 14(12), 1144-52.

Major contribution of Kepler was in discovering his laws of planetary motion, one of which states that planets move in elliptical orbits around the Sun which is located at one of the foci of the ellipse. T^Ke motion of a test particle in an inverse square force law is usually called the Kepler problem. We will examine several aspects of this motion in this last installment of Snippets in Physics.

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009476   Padmanabhan T (NO, , IUCAA, Post Bag 4, Pune, University Campus, Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in) : Snippets of physics, Real effects from imaginary time. Resonance 2009, 14(11), 1060-70.

Some of the curious effects in quantum theory and statistical mechanics can be interpreted by analytically continuing the time coordinate to purely imaginary values. We explore some of these issues in this instalment.

1 illus, 5 ref

009475   Padmanabhan T (NO, , Wigner Function, Semi-Classical Limit, Phase Space) : Snippets of physics, Wigner's function and semi-classical limit. Resonance 2009, 14(10), 934-43.

Obtaining the classical limit of quantum mechanics turns out to be conceptually and operationally non-trivial and, even today, some of the experts consider this issue to be unsettled. There is a function, originally devised by Wigner, which plays a key role in this aspect and throws some light on the way the classical world emerges from the quantum description.

1 illus, 1 ref

009474   Padmanabhan T (IUCAA, Pune Univ, Campus Ganeshkhind, Post Bag 4, Email: paddy@iucaa.ernet.in) : Snippets of physics, extreme physics. Resonance 2009, 14(9), 901-15.

Variational principles play a central role in theoretical physics in many guises. We will discuss, in this instalment, some curious features associated with a couple of variational problems.

3 illus, 2 ref

009473   Padmanabhan T (IUCAA, Pune Univ Campus, Post Bag 4, Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in) : Snippets of physics, perturbing coulomb to avoid accidents!. Resonance 2009, 14(6), 622-9.

Coulomb problem, which corresponds to motion in a potential that varies as r^{-1, has a peculiar symmetry which leads to a phenomenon known as 'accidental' degeneracy. This curious feature exists both in the classical and quantum domain and is best understood by studying a more general potential and obtaining the Coulomb problem as a limiting case.}

1 ref

009472   Padmanabhan T (NO, , IUCAA, Post Bag 4, Pune Univ Campus, Ganeshkhind, Pune-411 007, Email: paddy@iucaa.ernet.in) : Random walk through random walks - I. Resonance 2009, 14(7), 638-49.

Few processes in nature are as ubiquitous as the random walk which combines extraordinary simplicity of concept with considerable complexity in the final output. Examines several features of this remarkable phenomenon.

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009471   Padmanabhan T (IUCAA, Post Bag 4, Pune Univ Campus Ganeshkhind, Pune-411 007, , , Email: paddy@iucaa.ernet.in) : Snippets of physics - Optics of particles. Resonance 2009, 14(1), 8-18.

The probability amplitude for a particle to propagate from event to event in spacetime shows some nice similarities with the corresponding propagator for the electromagnetic wave amplitude discussed in the last installment. Provides an interesting insigh into the transition from quantum field theory to quantum mechanics.

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009470   Ogundare F O;Oniya E O;Balogun F A (Physics Dep, Ibadan Univ, Ibadan, Nigeria, Email: ogun_dare@yahoo.com) : Dependence of NaI(Tl) detector intrinsic efficiency on source-detector distance, energy and off-axis distance: their implications for radioactivity measurements. Pramana J Phys 2008, 70(5), 863-874.

In this work the dependence of intrinsic efficiency of a NaI(Tl) detector of radius 3.82 cm and height 7.62 cm on source-detector distance (d), source-off-axis distance (do) and 7-photon energy have been investigated using analytical and Monte Carlo methods. The results showed that, for a given off-axis distance, there exists a value of the ratio of source-detector distance (d) to detector radius (R) where intrinsic efficiency is minimum. This d/R value at which minimum efficiency occurs approaches zero as off-axis distance increases and it is almost constant with increase in energy, fn the region where d/R < 0.01, a criteria given by Jehouani et al [1] for good photon detection, intrinsic efficiency decreases with increasing off-axis distance. The implications of the results for radioactivity measurement and radiation protection are discussed. Chacteristics of intrinsic efficiency in the regions d/R < 0.01 and d/R > 10 are also compared.

7 illus, 11 ref

009469   Ngamga E J;Nandi A;Ramaswamy R;Romano M;Thiel M;Kurths J (Nonlinear Dynamics Group, Institute of Physics, Potsdam Univ, Potsdam 14415, Germany, Email: eulaliejoelle@yahoo.com) : Recurrences of strange attractors. Pramana J Phys 2008, 70(6), 1039-45.

The transitions from or to strange nonchaotic attractors are investigated by recurrence plot-based methods. The techniques used here take into account the recurrence times and the fact that trajectories on strange nonchaotic attractors (SNAs) synchronize. The performance of these techniques is shown for the Heagy-Hammel transition to SNAs and for the fractalization transition to SNAs for which other usual nonlinear analysis tools are not successful.

3 illus, 16 ref

009468   Nath M R;Sen S;Sen A K;Gangopadhyay G (Physics Dep, Guru Charan College, Silchar-788 004, Email: gautam@bose.res.in) : Dynamical symmetry breaking of lambda- and vee-type three-level systems on quantization of the field modes. Pramana J Phys 2008, 71(1), 77-97.

Developed a scheme to construct the Hamiltonians of the lambda-type, vee-type and cascade-type three-level configurations using the generators of SU(3) group. It turns out that this approach provides a well-defined selection rule to give different Hamiltonians for each configuration. The lambda- and vee-type configurations are exactly solved with different initial conditions while taking the two-mode classical and quantized fields. For the classical field, it is shown that the Rabi oscillation of the lambda model is similar to that of the vee model and the dynamics of the vee model can be recovered from lambda model and vice versa simply by inversion. We then proceed to solve the quantized version of both models by introducing a novel Euler matrix formalism. It is shown that this dynamical symmetry exhibited in the Rabi oscillation of two configurations for the semiclassical models is completely destroyed on quantization of the field modes. The symmetry can be restored within the quantized models when both field modes are in the coherent states with large average photon number which is depicted through the collapse and revival of the Rabi oscillations.

9 illus, 40 ref

009467   Nath M R;Dey T K;Sen S;Gangopadhyay G (Physics Dep, Guru Charan College, Silchar-788 004, Email: mrnath_95@rediffmail.com) : Effect of field quantization on rabi oscillation of equidistant cascade four-level system. Pramana J Phys 2008, 70(1), 141-52.

Solved a model of equidistant cascade four-level system interacting with a single-mode radiation field both semiclassically and quantum mechanically by exploiting its similarity with Jaynes-Cummings model. For the classical field, it is shown that the Rabi oscillation of the system initially in the first level (second level) is similar to that of the system when it is initially in the fourth level (third level). We then proceed to solve the quantized version of the model where the dressed state is constructed using a six-parameter four-dimensional matrix and show that the symmetry exhibited in the Rabi oscillation of the system for the semiclassical model is completely destroyed on the quantization of the cavity field. Finally, we have studied the collapse and revival of the system for the cavity field-mode in a coherent state to discuss the restoration of symmetry and its implication is discussed.

4 illus, 46 ref