004075   Hemalatha B;Vasantharani P;Vijayakumari K K; Selvakuari P (Physics Dep, St Matin's Engineering College, Kompally, Secunderabad, Andhra Pradesh, Email: hemalatha_gb@yahoo.com) : Ultrasonic studies of tetraethyammonium bomid and tetapropylammonium bromide in DMF-water systems at 303 K, 308 K and 313 K. Nano Vision 2013, 3(3), 197-202.

Ultrasonic velocities in solutions of tetraethylammonium bromide (TEAB) and tetrapropylammonium brom,ide (TPAB) in 10,20 and 30%w/w N,N-dimethylfomamaide (DMF)-water mixturd were measured at 303 K, 308 K and 313 K by using pulse echo overlap method at a frequency of 3 MHz. The ultrasonic velocity, density, and viscosity were used to calculate the adiabatic compressibility, apparent molal compressibility, apparent molal volume, limiting apparent molal compressibility, and limiting apparent molal volume. The observed variation in these parameters with respect to the molality highlights the type of interaction in the electrolytes and the structure making property of the salts.

2 tables, 5 ref

004074   Duarte Moller A (Centro de Investigacion en Materiales Avanzados, SC, , Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua 31109, Mexico, Email: duarte@cimav.edu.mx) : Electronic structure and first hyperpolarizability of paly (μ₂-L-alanine-μ₃-sod ium nitrate (I)) crystals. Bull Mater Sci 2014, 37(6), 1471-6.

Po1y(μ₂-L-alanine-μ₃-odium nitrate (I), p-LASN, crystals have been grown by slow evaporation at room temperature. The nominal size of the crystals obtained by the method was of 500 nm. The UV-Vis spectrum shows a wide range, where absorption is lacking around 532 nm, which is required in order to have the second harmonic emission, when an incident radiation of 1064 nm strikes on the crystal. This guarantees the possible use of the crystal in visible light applications. The transparent nature of the crystal in the visible and infrared regions within the transmission spectrum confirms the nonlinear optical properties of the crystal. Additionally, Fourier transform infrared spectroscopy displays its functional groups which correspond to the poly((μ₂-L-alanine-(μ₃-sod ium nitrate (I) where the presence of nitrates in the lattice generally can be identified by their characteristic signature within the 1660-1625, 1300-1255, 870-833 and 763-690 cm^{-1 range. Single crystal diffraction was carried out in order to determine atomic structure and lattice parameter. Structural parameters were a = 5ú388(9) Å, b = 9ú315(15) Å and c = 13ú63(2) Å. The structure of poly((μ₂-L-alanine-(μ₃-sod ium nitrate (I) shown by single crystal diffraction shows an asymmetric unit consisting of one sodium and one nitrate ion and one L-alanine molecule. The coordination geometry around the sodium atom was trigonal bipyramidal, with three bidentate nitrate anions coordinating through their oxygen atoms and two L-alanine molecules, each coordinating through one carboxyl oxygen atom. Electronic structure was obtained by using the Becke-Lee-Yang-Part and Hartree-Fock approximations with hybrid exchangeecorrelation three-parameter functional and G-311 **G(dp) basis set. Theoretical and experimental results were compared and discussed as having an excellent agreement among them.}

5 illus, 2 tables, 15 ref

004073   Dhall S;Jaggi N (Physics Dep, National Institute of Technology, Kurukshetra 136 119, Email: shivani.dha1124@gmail.com) : Improvement in structural and electrical properties of cuprous oxide-coated multiwalled carbon nanotubes. Bull Mater Sci 2014, 37(6), 1427-31.

In the present work, cuprous oxide (Cu₂O) nanoparticles are coated on multi-walled carbon nanotubes (MWCNTs) using Fehling's reaction. The coating of Cu₂O nanoparticles on the nanotubes was confirmed by SEM and X-ray diffraction (XRD) spectra. The calculated I_D/I_G ratio of Cu₂O (using 3% CuSO₄ by wt)-coated MWCNTs by Raman spectra is found to decrease to 0ú94 as compared to 1ú14 for pristine MWCNTs. It shows that the presence of Cu₂O nanoparticles on nanotubes decreases the inherent defects present in the form of some pentagons/heptagons in the honeycomb hexagonal carbon atoms in the structure of graphene sheets of MWCNTs and increases the crystalline nature of MWCNTs, which is also confirmed by the XRD peaks. Whereas the value of I_D/I_G ratio increases to 1ú39 for sample 2 (using 5% CuSO₄4 by wt), which represents the structural deformation. Moreover, the electrical conductivity of MWCNTs was increased by 3 times after coating the nanotubes with CU₂O (using 3% CUS04 by wt).

7 illus, 25 ref

004072   Das S K;Mandal A B (CSIR-Central Leather Research Institute, , Chennai-600 020, Email: sujoy@clri.res.in) : Green synthesis of nanomaterials with special reference to environmental and biomedical applications. Curr Sci 2015, 108(11), 1999-2002.

Environmental benign bioinspired and/or biomimetic synthetic process of metal nanoparticles have been developed for water purification and biomedical applications. In the synthetic process, the biomolecules acted as shape directing agent determining the crystal structure of the nanoparticles and also control the surface properties of the nanomaterials.

3 illus, 3 ref

004071   Das R;Sarkar S (Nano-Physics and Nanotechnology Research Lab, Physics Dep, Tripura university, Tripura-799 022, Email: dastratanphy@gmail.com) : Determination of intrinsic strain in poly(vinylpyrrolidone)-capped silver nano-hexapod using X-ray diffraction technique. Curr Sci 2015, 109(4), 775-8.

Poly(vinylpyrrolidone)-capped silver nano-hexapods (AgNHs) have been prepared by chemical reduction method using ethylene glycol as a reducing agent, for the study of their structural and elastic properties. HRTEM study reveals that the prepared nanocrystals are hexapod in shape with an average size of approximately 50nm. From the analysis of the X-ray diffraction pattern, intrinsicstrain produced in the nano-hexapod due to dislocation of silver atoms, has been determined from the W-Hplot. The lattice constant of the AgNHs has also been determined from Nelson-Riley plot. Higher value of dislocation density confirms that there may exist intrinsic strain in the nanocrystals.

5 illus, 25 ref

004070   Dakhel A A (Physics Dep, College of Science, University of Bahrain, P O Box 32038, Kingdom of Bahrain, Email: adakhil@uob.edu.bb) : Influence of Be doping on the characteristics of CdO/p-Si heterojunction for optoresponse applications. Bull Mater Sci 2014, 37(6), 1509-14.

In this work, the optoelectronic properties of Be-doped CdO films grown on p-Si forming CdO : Be/p-Si hetero-p-n junctions were investigated. The spotlight was on the influence of electronic properrties of CdO : Be layers, which were controlled by Be-dopant content, on the optoelectronic properties of the constructed p-n heterojunction. The characterization of the transparent conducting oxide CdO : Be layer was performed with X-ray diffraction, scanning electron microscopy, electrical measurements and spectral phootometry. It was found that Be doping greatly enhanced the optoresponse (S*) of the p-n heterojunction, such that S* was boosted by <126>36 times for CdO: 0ú10% Be/p-Si sample, compared with the undoped CdO/p-Si. This S*-enhancement was explained by the improvement of carrier mobility in host CdO with Be doping. Thereefore, the utmost S* that was found with 0ú10% Be-doped CdO sample was due to its highest carrier mobility among other samples of different Be content. The results of optoelectronic measurements in visible and NIR spectral range demonstrate the utility of the CdO : Be/p-Si heterojunction in photodetection applications.

8 illus, 23 ref

004069   Dahoudi N A (Physics Dep, Al Azhar University, Gaza, P O Box 1277, Gaza, Palestine) : Comparative study of highly dense aluminium- and gallium-doped zinc oxide transparent conducting sol-gel thin films. Bull Mater Sci 2014, 37(6), 1243-8.

Transparent conducting aluminium- and gallium-doped zinc oxide (AZO and GZO) layers have been deposited by spin coating on glass substrates. The coatings have been sintered in air at 450°C for 30 min and then post-annealed at 350°C in a reducing atmosphere for 30 min. The electrical, optical and morphological properties of both coatings have been studied and compared. The conventional sols lead to very thin coating, typically 24 nm for a single layer of AZO and 32 nm of GZO with electrical resistivity of 0ú72 and 0ú35 n cm, respectively. The value however, drastically decreases down to a minimum of 2ú6 x 10^{-2 Ω cm for AZO and 1ú76 x 10-2 Ω five multilayer coatings are made. The origin of these differences is due to the different morphology of the coatings showing different electron scattering process. The GZO sol leads to denser smoother structure (porosity of 5%) layers with an average roughness of 2ú76 A, while the AZO coating is formed by a more porous assembly (porosity of 20%) with an average roughness of 3ú46 A. Both coatings exhibit high transparency (T<62> 85%) in the visible spectrum range with a slight shift of the absorption energy gap.}

7 illus, 20 ref

004068   Balbour M R;Hosni H M;Soliman M A;Fayek S A (National Centre for Radiation Research and Technology, , P O Box 29, Nasr City, Cairo, Egypt, Email: m_balboul@yahoo.com) : Effect of composition on optical properties of GeSe₃-Sb₂Se₃-ZnSe thin films. Bull Mater Sci 2014, 37(6), 1255-63.

Optical properties of the chalcogenides GeSe₃, Sb₂Se₃, ZnSe, (GeSe₃)₈₀(Sb₂Se₃)₂₀ and (GeSe₃)₇₀ (Sb₂Se₃)₁₀(ZnSe)₂₀ thin films are investigated. Incorporation of ZnSe into both GeSe₃, Sb₂Se₃ results in amorphous (GeSe₃)₇₀(Sb₂Se₃)_10>(ZnSe)₂₀ composition. The estimated optical energy gap, E_g, is found to decrease from 3ú06 eV for ZnSe to 1ú81 eV for (GeSe₃)₇₀(Sb₂Se₃)₁₀(ZnSe)₂₀. While, the band tail width, E_e, exhibits an opposite trend. The E_g behaviour is believed to be associated with cohesive energy, CE, as the incorporation of ZnSe lowers its value. The calculated number of the excess of Se-Se homopolar bonds is found to affect mainly the E_e values. The refractive index, n, is discussed in terms of Wemple-DiDomenico single oscillator dispersion model in the normal dispersion region. The oscillator energy, E_o, and the dispersion energy, E_d, are determined for films under investigation.

9 illus, 3 tables, 22 ref

004067   Ardyanian M;Sedigh N (School of Physics and Centre for Solid State Physics Research, Damghan University, 3671641167, Damghan, Iran, Email: ardyanian@du.ac.ir) : Heavy lithium-doped ZnO thin films prepared by spray pyrolysis method. Bull Mater Sci 2014, 37(6), 1309-14.

Lithium-doped ZnO thin films (ZnO : Li_x) were prepared by spray pyrolysis method on the glass substrates for x (x = [Li]/[Zn]) value varied between 5 and 70%. Structural, electrical and optical properties the samples were studied by X-ray diffraction (XRD), UV-Vis-NIR spectroscopy, scanning electron microscopy (SEM), Hall effect and sheet resistance measurements. XRD results show that for x ≤ 50%, the structure of the films tends to be polycrystals of wurtzite structure with preferred direction along (0 0 2). The best alline order is found at x = 20% and the crystal structure is stable until x = 60%. The Hall effect results ribe that Li doping leads to change in the conduction type from n- to p-type, again it changes to n-type at x = 70% and is attributed to self-compensation effect. Moreover, the carrier density was calculated in the order of 10^{13 cm-3. The resistivity of Li-doped films decreases until 22 Ω cm at x = 50%. Optical bandgap was reduced slightly, from 3ú27 to 3ú24 eV as a function of the grain size. Optical transmittance in the visible range reaches T = 97%, by increasing of Li content until x = 20%. Electrical and optical properties are coherent with structural results.}

5 illus, 2 tables, 29 ref

003086   Sahijpal S;Bhatia G K (Physics Dep, Panjab Univ, Chandigarh-160 014, Email: sandeep@pu.ac.in) : The role of impact and radiogenic heating in the early thermal evolution of mars. J Earth Syst Sci 2015, 124(1), 241-60.

The planetary differentiation models of Mars are proposed that take into account core-mantle and core- mantle-crust differentiation. The numerical simulations are presented for the early thermal evolution of Mars spanning up to the initial 25 million years (Ma) of the early solar system, probably for the first time, by taking into account the radiogenic heating due to the short-lived nuclides, ^{26A1 and 60Fe. The influence of impact heating during the accretion of Mars is also incorporated in the simulations. The early accretion of Mars would necessitate a substantial role played by the short-lived nuclides in its heating. 26A1 along with impact heating could have provided sufficient thermal energy to the entire body to substantially melt and trigger planetary scale differentiation. This is contrary to the thermal models based exclusively on the impact heating that could not produce widespread melting and planetary differentiation. The early onset of the accretion of Mars perhaps within the initial <126>1.5 Ma in the early solar system could have resulted in substantial differentiation of Mars, provided, it accreted over the timescale of <126>1 Ma. This seems to be consistent with the chronological records of the Martian meteorites.}

8 illus, 1 table, 59 ref

003085   Mathew N;John V O;Suresh Raju C;Krishna Moorthy K (Space Physics Laboratory, Vikram Sarabhai Space Centre, Indian Space Research Organization, Thiruvananthapuram-695 022, Email: c_sureshraju@vssc.gov.in) : Upper tropospheric humidity from SAPHIR on-board megha-tropiques. Curr Sci 2015, 108(10), 1915-22.

Upper tropospheric humidity (UTH) has been derived using a 'brightness temperature (T_b) transformation' method from the humidity sounder channels of SAPHIR payload on-board Megha-Tropiques (MT). These channels are very close to the water vapour absorption peak at 183.31 GHz. The channel at 183.31 ± 0.2 GHz enables retrieval of humidity up to the highest altitude possible with the present nadir-looking microwave humidity sounders. Megha-Tropiques satellite has an equatorially inclined orbit, which ensures frequent spatial and temporal coverage of the global tropical belt. Transformation coefficients for the first three channels for all the incidence angles have been derived and are used to convert brightness temperatures to weighted average upper tropospheric humidity having weighting function peaks at different pressure levels. The methodology has been validated by comparing the SAPHIR-derived UTH with that derived from radiosonde observations. Inter-comparison of the derived UTH has been done with layer averaged humidity product from SAPHIR measurements and with UTH product using infrared measurements from Kalpana satellite (MOSDAC). UTH over the tropical belt for six months has been studied taking the advantage of the humidity product with high spatial and temporal resolution. The transformation coefficients and methodology to identify the cloud-free pixels to derive UTH from the three channels for all the possible incidence angles are presented here, so that the users can directly derive UTH from the brightness temperature data.

7 illus, 3 tables, 22 ref

003084   Mathan N (ECE Dep, Sathyabama Univ, Chennai, Email: mathanmaestro@hotmail.com) : CNTFET based highly durable radix-4 multiplier using an efficient hybrid adder. Biosci Biotechnol Res Asia 2014, 11(3), 1855-60.

CNTFET is a novel device that is projected to outperform scaled CMOS technologies.Multiplier is one of the very important hardware blocks such as FIR filters, digital signal processors etc.The performance speed of the multiplier often affects the overall speed performance in VLSI systems. On the whole, multiplication employs most of the execution time in many Digital signal processor (DSP) devices. So, high speed multiplier is greatly desired. In this paper, a high speed existing radix-4 multiplier based Shannon adder is analysed intensively. To achieve an efficient radix-4 multiplier, the proposed hybrid adder was implemented for further power reduction in high speed parallel radix-4 multiplier circuits. The proposed radix-4 multiplier is more desirable for obtaining the low power consumption, less propagation delay and efficient power delay product. Simulations are executed using Synopsys HSpice in 32nm CMOS and 32nm CNTFET Technologies. The simulation results exhibits the transcendences of the proposed structures in terms of Power consumption, propagation delay and Power delay product compared to the advanced technology of CMOS and CNTFET based designs.

10 illus, 2 tables, 12 ref

003083   Kalytka V A;Isaev V L;Tatkeyeva G G;Taranov A V;Kamarova S N (NO, Karaganda State Technical Univ, Kazakhstan, 100000, Karaganda city, Mira Street, 56) : Quantum properties of dielectric losses spectra in lamellar crystals at extra-low temperatures. Biosci Biotechnol Res Asia 2014, 11(3), 1601-9.

Quantum mechanism of interlayer polarization in condensed mediums in alternating electric field in the limits of low and extra-low temperatures is studied. Unbalanced density matrix is calculated for the ensemble of noninteracting protons, moving in one-dimension multipit potential image of rectangular shape in variable polarizing field. With the help of unbalanced density matrix, anomalous effects are studied, connected with the move of low-temperature maximum loss tangent of dielectric in lamellar crystals towards the temperatures of liquid helium. Results of quantum-mechanical calculation of spectra of complex dielectric permittivity (SCDP) may be used in the study of tunnel mechanism of spontaneous polarization of ferrielectrics (KDP, DKDP).

20 ref

003082   Gupta S;Sultana R;Kundu S (Applied Mathematics Dep, Indian School of Mines, Dhanbad-826 004, Email: shishir_ism@yahoo.com) : Influence of rigid boundary on the propagation of torsional surface wave in an inhomogeneous layer. J Earth Syst Sci 2015, 124(1), 161-70.

The present work illustrates a theoretical study on the effect of rigid boundary for the propagation of torsional surface wave in an inhomogeneous crustal layer over an inhomogeneous half space. It is believed that the inhomogeneity in the half space arises due to hyperbolic variation in shear modulus and density whereas the layer has linear variation in shear modulus and density. The dispersion equation has been obtained in a closed form by using Whittaker's function, which shows the variation of phase velocity with corresponding wave number. Numerical results show the dispersion equations, which are discussed and presented by means of graphs. Results in some special cases are also compared with existing solutions available from analytical methods, which show a close resemblance. It is also observed that, for a layer over a homogeneous half space, the velocity of torsional waves does not coincide with that of Love waves in the presence of the rigid boundary, whereas it does at the free boundary. Graphical user interface (GUI) software has been developed using MATLAB 7.5 to generalize the effect of various parameter discussed.

5 illus, 1 table, 26 ref

003081   Al-Amiedy D H;Saleh Z A;Al-Yasari R K (Physics Dep, College of Science for Women, Univ. of Baghdad, Iraq) : Spin -orbit coupling, spin-spin, and electric properties of hydrogen bromide molecule. Asian J biochem pharm Res 2014, 4(3), 258-62.

Research includes the study of the spin- orbit coupling, spin- spin, electronic structure and number electric properties such as ionization potential(IP), electron affinity(EA), electronegativity (x), hardness(η), softness(S), and electrophilic(W)of hydrogen bromide molecule by using Gaussian program 09 and Gauss view 5.08 program using density function (DFT) method B3LYP/6-311G (d,p). It has been found that the values of spin -orbit coupling are decreasing with increasing the bond length between hydrogen and bromide atoms. Because the bromide has high electronegativity, therefore bromide attached the electrons towered themselves this electrons lead to shielding the bromide for hydrogen atom, this indicated that the spin-orbit coupling and spin-spin are depending on the bond length, also the diamagnetic shielding.

13 ref

002186   Sethi M (NO, National Institue of Urban Affairs, Core 4B, Email: mahendrasethi@hotmail.com) : Decoding urban India's carbon footprint: spatial-numerical mapping of thermal energy emissions. Curr Sci 2015, 108(9), 1616-23.

Greenhouse gases (GHGs) are the prime cause of climate change, to which India is a significant party. International Energy Agency, in its World Energy Outlook report estimates that 70% of the GHGs are produced within the cities. But there is limited empirical evidence to substantiate such claims in the Indian context. India being a developing country with a large rural population base, the general perception is that cities hardly have any carbon footprint. This article is an empirical study of urban contribution of carbon dioxide emissions. In the absence of any international protocol or a standard methodology to estimate urban footprint of a nation, this article deals with theoretical issues evident while allocating city emissions like methodological differences, defining 'urban' and its boundary and the need to consider downscaling of nationally reported emissions using spatial analysis based on production or location perspective of the most significantly contributing sector namely electricity generation. The information has been assessed on the urban-rural gradient, using population-based Census definition for class/hierarchy of towns and their location with respect to the urban boundary. The results present an array of emissions, across the urban hierarchy and location in space, underpinning how substantial emissions are attributable to urban and urbanizing areas. The findings bear significance to influence research, policy and action in urban energy and ensure greater climate co-benefits at the local level.

5 illus, 2 tables, 36 ref

002185   Nityananda R (NO, Azim Premji Univ, PES Institute of Technology Campus Pixel Park, B Block Electronics City, Hosur Road (Beside NICE Road), Bengaluru-560 10, Email: rajaram.nityananda@gmail.com) : Diffraction at a straight edge. Resonance 2015, 20(5), 389-400.

The simplest problem in diffraction - light passing a straight edge - did not receive a rigorous solution till Sommerfeld's work of 1896. The earlier theories, their successes and their limitations are recounted. They led upto Sommerfeld's final solution which had eluded many great contemporaries. This solution was a landmark of rigorous diffraction theory.

3 illus

002184   Biman Nath (NO, Raman Research Institute C V Raman Avenue Sadashivnagar, Bengaluru-560 080) : Fine structure constant. Resonance 2015, 20(5), 383-8.

Article discusses the importance of the fine structure constant in quantum mechanics, along with the brief history of how it emerged. Although Sommerfelds idea of elliptical orbits has been replaced by wave mechanics, the fine structure constant he introduced has remained as an important parameter in the field of atomic structure.

1 illus

001087   Ghosh N P (NO, Research scholar of Burdwan Univ, Burdwan, West Bengal, Email: nabaprasadghosh62@gmail.com) : Application of non-conventional and renewable energy sources in India and its future prospect. Indian J Landsc Syst ecol Stud 2014, 37(1), 103-9.

Energy security has an important bearing on achieving national economic development goals and improving the quality of life of the people. Therefore the level of per capita consumption of energy is directly proportional to the progress of economic growth of any country. The achievement of energy security necessitates diversification of our energy resources and the sources of their supply, as well as measures for conservation of energy. We were depending on different sources of conventional energy like fossil fuels (coal, oil and natural gas), types of nuclear (uranium) and hydel power which causes global warming, urban air pollution, and acid rain. It strongly suggests that the time has now come to use the non-conventional and renewable energy resources. Renewable energy resources are sources that are continuously replenished by natural processes, can never be exhausted. In India, non-conventional energy sources are infinite, natural, and restorable as for example, tidal energy, solar energy, and wind energy etc. In this paper an attempt has been made to present the various sources of renewable and nonconventional energy sources, their application and its future prospect in India.

5 tables, 12 ref

001086   Fengxiao Z;Guang Y;Kun Y;Mingju H (College of Physics & Electronics Engineering, Zhengzhou Univ of Light Industry, Zhengzhou 450002, P.R. China, Email: fxzhai2008@hotmail.com) : Two dyes co-sensitized photopolymer for multi-wavelength holographic recording. J Polym Mater 2014, 31(2), 225-32.

Novel wide band photopolymer sensitized by Erythrosin B (ErB) and Methylene Blue (MB) is fabricated. The sensitive spectrum band of photopolymer exceeds 200nm in the visible light range due to the addition of two dyes. The holographic performances of the material are investigated under exposure of different wavelengths. The results show that the maximum diffraction efficiency, refractive index modulation and exposure sensitivity increases with the increase of the exposure wavelength. It is found that the photopolymer is suitable for wavelength multiplexing or multi-wavelength recording in digital holographic storage.

6 illus, 1 table, 19 ref

000072   Zolfagharian N;Rezagholipour Dizaji H (Faculty of Physics, Semnan Univ, Opposite of Sokan Park, Semnan 35131-19111, Iran, Email: hrgholipour@semnan.ac.ir) : Growth and characterization of TGS single crystal doped with NiSO₄ grown by Sankaranarayanan-Ramasamy method. Indian J pure appl Phys 2015, 53(4), 234-8.

Unidirectional <60>001<62> NiSO₄ doped triglycine sulphate (TGS) single crystal of 15 mm in diameter and 150 mm in length was successfully grown in aqueous solution by Sankaranarayanan-Ramasamy (S-R) method. The characterization of the grown crystal was made by powder X-ray diffraction, UV-Vis. spectroscopy, Fourier transform infrared spectroscopy (FTIR), Vicker's microhardness studies. The X-ray diffraction analysis revealed a monoclinic structure for the grown crystal. UV-Vis. analysis showed high transmittance for the doped TGS crystal in the entire visible region. FTIR spectrum verified the presence of various functional groups in the grown specimen. Vicker's microhardness studies of the doped TGS crystal showed that it is harder than pure TGS crystal. The density of the doped crystal was found to be higher than that of the undoped one.

5 illus, 34 ref

000071   Vishnu Priya N;Senthilvelan M;Lakshmanan M (Centre for Nonlinear Dynamics, School of Physics, Bharathidasan Univ, Tiruchirappalli-620 024, Email: velan@cnld.bdu.ac.in) : Breathers and rogue waves: demonstration with coupled nonlinear schrodinger family of equations. Pramana J Phys 2015, 84(3), 339-52.

Different types of breathers and rogue waves (RWs) are some of the important coherent structures which have been recently realized in several physical phenomena in hydrodynamics, nonlinear optics, Bose-Einstein condensates, etc. Mathematically, they have been deduced in non-linear Schrodinger (NLS) equations. Here we show the existence of general breathers, Akhmediev breathers, Ma soliton and rogue wave solutions in coupled Manakov-type NLS equations and cou-pled generalized NLS equations representing four-wave mixing. We deduce their explicit forms using Hirota bilinearization procedure and bring out their exact structures and important properties. We also show the method to deduce the various breather solutions from rogue wave solutions using factorization form and the so-called imbricate series.

6 illus, 30 ref

000070   Uzma G (Physics Dep, Wah Univ, Wah Cantt, Pakistan, Email: uzigh@yahoo.com) : Effect of Si on the dielectric properties of Ni_x Zn_1-x Fe₂O₄ as a function of composition and frequency. Indian J pure appl Phys 2015, 53(4), 271-3.

Nickel-zinc ferrites of composition Ni_xZn_1-xFe₂O₄ (x=0.66, 0.77, 0.88, 0.99) were prepared by the usual ceramic technique. The dielectric properties have been studied as a function of composition and frequency. It is observed that the values of dielectric constant ∈ and dielectric loss factor tanδ for samples prepared in the present work are much lower and of reduced price than those commercially obtained Ni-Zn ferrites. These low values are attributed to the presence of Si in Fe₂O₃ powder. It has been found that the ceramic grain growth was suppressed by Si, which results in a decrease in the dielectric constant and dielectric loss factor. The dielectric constant ∈' and loss tangent tan d also decrease as the frequency of applied ac electric field increases.

4 illus, 18 ref

000069   Thampi S P;Govindarajan R (NO, The Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford, OX1 3NP, UK, Email: sumesh.thampi@physics.ox.ac.uk) : Rolling motion in moving droplets. Pramana J Phys 2015, 84(3), 409-21.

Drops moving on a substrate under the action of gravity display both rolling and sliding motions. The two limits of a thin sheet-like drop in sliding motion on a surface, and a spherical drop in roll, have been extensively studied. We are interested in intermediate shapes. We quantify the contribution of rolling motion for any intermediate shape, and recently obtained a universal curve for the amount of roll as a function of a shape parameter using hybrid lattice Boltzmann simulations. In this paper, we discuss the linear relationship which is expected between the Capillary and Bond numbers, and provide detailed confirmation by simulations. We also show that the viscosity of the surrounding medium can qualitatively affect dynamics. Our results provide an answer to a natural question of whether drops roll or slide on a surface and carry implications for various applications where rolling motion may or may not be preferred.

7 illus, 32 ref

000068   Subash B;Chandrasekar V K;Lakshmanan M (Centre for Nonlinear Dynamics, Physics Dep, Bharathidasan Univ, Tiruchirappli-620 024, Email: lakshman@cnld.bdu.ac.in) : Nonlinear dynamics of spin transfer nano-oscillators. Pramana J Phys 2015, 84(3), 473-85.

The evolution equation of a ferromagnetic spin system described by Heisenberg nearest-neighbour interaction is given by Landau-Lifshitz-Gilbert (LLG) equation, which is a fascinating nonlinear dynamical system. For a nanomagnetic trilayer structure (spin valve or pillar) an additional torque term due to spin-polarized current has been suggested by Slonczewski, which gives rise to a rich variety of dynamics in the free layer. Under appropriate conditions the spin-polarized current gives a time-varying resistance to the magnetic structure thereby inducing magnetization oscillations of frequency which lies in the microwave region. Such a device is called a spin transfer nanooscillator (STNO). However, this interesting nanoscale level source of microwaves lacks efficiency due to its low emitting power typically of the order of nWs. To overcome this difficulty, one has to consider the collective dynamics of synchronized arrays/networks of STNOs as suggested by Fert and coworkers so that the power can be enhanced N^{2 times that of a single STNO. We show that this goal can be achieved by applying a common microwave magnetic field to an array of STNOs. In order to make the system technically more feasible to practical level integration with CMOS circuits, we establish suitable electrical connections between the oscillators. Although the electrical connection makes the system more complex, the applied microwave magnetic field drives the system to synchronization in large regions of parameter space.}

10 illus, 29 ref

000067   Shanker J;Singh P K;Saurabh S (Physics Dep, Institute of Basic Sciences, Dr B R Ambedkar Univ, Khandari Campus, Agra-282 002, Email: pramod0002000@yahoo.com) : Analysis of infinite pressure behaviour of thermoelastic properties of materials. Indian J pure appl Phys 2015, 53(4), 230-33.

Thermoelastic properties have been determined in the limit of infinite pressure by considering the material to remain in the same phase up to extreme compression. We have used some basic principles of calculus in various thermodynamic identities to extrapolate thermoelastic properties at infinite pressure. The results thus obtained are found to be consistent with the earlier investigations made by Stacey (Rep Prog Phys, 68 (2005)341). It has been proved in the present study that the logarithmic volume derivatives of the Anderson-Grneisen parameters become zero at infinite pressure. This finding has further been used to obtain new results for higher order thermoelastic parameters at extreme compression.

15 ref

000066   Sahoo G S;Tripathy S P;Paul S;Sharma S D; Sharma S C;Joshi D S;Bandyopadhyay T (Health Physics Div, Bhabha Atomic Research Centre, Mumbai, Maharashtra) : Neutron dose estimation via LET spectrometry using CR-39 detector for the reaction <. J med Phys 2014, 39(4), 225-30.

It is widely accepted that a redundant independent dose calculation (RIDC) must be included in any treatment planning verification procedure. Specifically, volumetric modulated arc therapy (VMAT) technique implies a comprehensive quality assurance (QA) program in which RIDC should be included. In this paper, the results obtained in 1 year of clinical experience are presented. Eclipse from Varian is the treatment planning system (TPS), here in use. RIDC were performed with the commercial software; Diamond^{® (PTW) which is capable of calculating VMAT fields. Once the plan is clinically accepted, it is exported via Digital Imaging and Communications in Medicine (DICOM) to RIDC, together with the body contour, and then a point dose calculation is performed, usually at the isocenter. A total of 459 plans were evaluated. The total average deviation was -0.3 ± 1.8% (one standard deviation (1SD)). For higher clearance the plans were grouped by location in: Prostate, pelvis, abdomen, chest, head and neck, brain, stereotactic radiosurgery, lung stereotactic body radiation therapy, and miscellaneous. The highest absolute deviation was -0.8 ± 1.5% corresponding to the prostate. A linear fit between doses calculated by RIDC and by TPS produced a correlation coefficient of 0.9991 and a slope of 1.0023. These results are very close to those obtained in the validation process. This agreement led us to consider this RIDC software as a valuable tool for QA in VMAT plans.}

7 illus, 2 tables, 26 ref

000065   Safarpour G;Izadi M A;Novzari M;Niknam E (Young Researchers and Elite Club, Shiraz Branch, Islamic Azad Univ, Shiraz, Iran, Email: safarpour.ghasem@gmail.com) : External electric field effect on the nonlinear optical properties of a laser dressed donor impurity in a GaAs spherical quantum dot confined at the center of a Ga_1-xA1_x as cylindrical nano-wire. Indian J pure appl Phys 2015, 53(4), 247-56.

Linear and third order nonlinear optical absorption coefficients and refractive index changes of an on-center donor impurity in a spherical GaAs quantum dot which is located at the center of a cylindrical Ga_1-xAl_xAs nano-wire, have been investigated under the simultaneous effect of electric field and laser radiation. The linear and third order nonlinear optical properties are calculated based on optical 1-2, 2-3 and 1-3 transitions by means of the compact density-matrix approach. The energy eigenvalues and corresponding wave functions are calculated using finite difference approximation and reliability of calculated wave functions is checked by computing orthogonality. It is shown that optical spectrum shifts towards lower and higher energies for 1-2 transition and shifts towards lower energies for 2-3 and 1-3 transitions as the electric field strength increases. The presence of laser field shifts absorption spectrum towards lower energies. In the absence of electric and laser field, the magnitude of absorption coefficient and refractive index changes increase in transitions between higher levels. Simultaneous presence of both electric field and laser radiation has great effect on magnitude of absorption coefficients and refractive index changes. The saturation in optical spectrum can be adjusted by electric field and laser radiation.

6 illus, 45 ref

000064   Ray S S (International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bangalore-560 012, Email: samriddisankarray@gmail.com) : Thermalized solutions, statistical mechanics and turbulence: an overview of some recent results. Pramana J Phys 2015, 84(3), 395-407.

In this study, we examine the intriguing connection between turbulence and equilibrium statistical mechanics. There are several recent works which emphasize this connection. Thus in the last few years, the first manifestations of the thermalization, predicted by T D Lee in 1952, was seen and a theoretical understanding of this was developed through detailed studies of finite-dimensional, Galerkin-truncated equations of hydrodynamics. Furthermore, the idea of the Galerkin truncation can be generalized for studying turbulence in non-integer (fractal) dimensions to yield a new, critical dimension with an equilibrium Gibbs state coinciding with a Kolmogorov spectrum. In this paper, we discuss these very exciting and recent developments in turbulence as well as open problems for the future.

3 illus, 59 ref

000063   Pal U N;Prajapati J;Niraj Kumar;Ram Prakash (Microwave Tubes Div, CSIR-Central Electronics Engineering Research Institute (CEERI), Pilani-333 031, Email: paludit@gmail.com) : Particle-in-cell simulation study of PCE-gun for different hollow cathode aperture sizes. Indian J pure appl Phys 2015, 53(4), 225-9.

Pseudospark (PS) discharge is promising source for high brightness and high intensity electron beam pulses. In the present paper, an effort has been made to analyse the temporal behaviour of discharge current, applied voltage, plasma density in the PS discharge based PCE-Gun at different hollow cathode aperture sizes using 3-D particle-in-cell (PIC) simulation code "VORPAL". The peak discharge current in the PS discharge is a function of hollow cathode dimensions. The plasma generation process by self ionization discharge is examined at different operating conditions. Argon is taken as the background neutral gas. It has been observed that the decrease in the aperture size from 8 mm to 3 mm increases the discharge current, the electron confinement time and the plasma density.

7 illus, 11 ref

000062   Medhat M E;Mohammad A Z;Rahman S;Singh V P (Experimental Nuclear Physics Dep, Nuclear Research Centre, P.O. 13759, Cairo, Egypt, Email: medhatme@ymail.com) : Study of photon interaction parameters in some newly developed superconductors. Indian J pure appl Phys 2015, 53(4), 257-62.

The total mass attenuation coefficients, effective atomic numbers and electron densities in some recent and newly discovered non-centrosymmetric (NCS) and iron-based superconductors have been calculated for total and partial photon interactions in the wide energy range 1 keV-100 GeV. The values of these parameters have been found to change with composition of the superconductor and change in energy whereas their behaviour has been found to be identical with all energies. The variations of these parameters with energy are shown graphically for all photon interactions. The reported data could be useful for comparing these superconductors in terms of radiation sensitivity and radiation detection. The results of this work can stimulate research for other materials and different types of newly superconductors.

10 illus, 2 tables, 18 ref

000061   Manjunatha H C (NO, Government College for Women, Opposite to Kolaramma Temple, Kolar, Karnataka-563 101, Email: manjunathhc@rediffmail.com) : A study of photon interaction parameters in lung tissue substitutes. J med Phys 2014, 39(2), 112-5.

The study of photon interaction with different composite materials has become a topic of prime importance for radiation physicists. Some parameters of dosimetric interest are the mass attenuation coefficient, effective atomic number, and electron density; these help in the basic understanding of photon interactions with composite materials. The photon interaction parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Z_eff), and effective electron density (N_el) must be identical for the phantom material and their tissue. In the present study, we have evaluated the photon interaction parameters such as (μ/ρ), Z_eff and N_el of 13 lung tissue substitutes. The variations of these parameters of lung tissue substitutes with photon energy are graphically represented. The photon interaction parameters of lung tissue substitutes are compared with that of lung tissue. The variation of photon interaction parameters of the studied lung tissue substitutes is similar that of the lung. Logically, it can be shown that Alderson lung is good substitute for lung than the other substitutes.

3 illus, 3 tables, 12 ref

000060   Luo M;Guo W L;Zhang X R;Meng X G (Biology and Chemical Engineering Dep, Jiangsu Univ of Science and Technology Zhenjiang, Jiangsu, 212003, China, Email: guow1954@163.com) : Structural, stability and electronic properties of Os_mC_n (m+N≤7) clusters. Indian J pure appl Phys 2015, 53(4), 239-46.

The structures, relative stabilities and electronic properties of Os_mC_n clusters for m+n≤7 have been investigated by the density functional theory. The planar geometries have been preferred for small carbon mixed clusters up to m+n=5, for those with size of m+n≥6, the C-rich clusters are still planar structures, while Os-rich clusters are three-dimensional structures, and the most energetic favourable structures tend to be capped pyramid or irregular prism. The stability analysis indicates that the mixed clusters are more stable than those of the corresponding pure Os_n clusters, among which O_sC₂, Os₂C₂, Os₄C₂, Os₂C₄ exhibit higher stability than their neighbouring clusters. Os5d and C2p electrons play dominant roles in chemical reaction of mixed clusters.

6 illus, 25 ref

000059   Kolwankar K M;Prakash P;Radhakrishnan S;Sahu S;Dharmadhikari A K;Dharmadhikari J A;Mathur D (Physics Dep, Ramniranjan Jhunjhunwala College, Ghatkopar(W), Mumbai-400 086, Email: kiran.kolwankar@gmail.com) : Effect of heat source on the growth of dendritic drying patterns. Pramana J Phys 2015, 84(3), 387-94.

Shining a tightly-focussed but low-powered laser beam on an absorber dispersed in a biological fluid gives rise to spectacular growth of dendritic patterns. These result from localized drying of the fluid because of efficient absorption and conduction of optical energy by the absorber. We have carried out experiments in several biologically relevant fluids and have analysed patterns generated by different types of absorbers. We observe that the growth velocity of branches in the dendritic patterns can decrease below the value expected for natural drying.

3 illus, 16 ref

000058   Kassis A;Saad M (NO, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus, Syria, Email: pscientific2@aec.org.sy) : Theoretical investigation of the effect of Ga content on the power conversion efficiency in ZnO/CdS/Cu(In,Ga)Se₂ cells. Indian J pure appl Phys 2015, 53(4), 263-70.

Power conversion efficiency of solar cells is theoretically expected to have its maximum at an absorber energy band gap of E_g ≈ 1.4 eV, but experimentally it is found at E_g = 1.18 eV for ZnO/CdS/Cu(In,Ga)Se₂ cells. In the present work, the explanation of this shift is sought in terms of optical losses through the window layer and interface recombination. The calculated results are compared with theoretical and experimental findings as reported in the literature.

3 illus, 39 ref

000057   Kanna T;Sakkaravarthi K;Vijayajayanthi M; Lakshmanan M (Physics Post Graduate and Research Dep, Bishop Heber College, Tiruchirappalli-620 017, Email: kanna_phy@bhc.edu.in) : Dynamics of solitons in multicomponent long wave-short wave resonance interaction system. Pramana J Phys 2015, 84(3), 327-38.

In this paper, we study the formation of solitons, their propagation and collision behaviour in an integrable multicomponent (2+l)-dimensional long wave-short wave resonance interaction (M-LSRI) system. First, we briefly revisit the earlier results on the dynamics of bright solitons and demonstrate the fascinating energy exchange collision of bright solitons appearing in the short-wave components of the M-LSRI system. Then, we explicitly construct the exact one-and two-multicomponent dark soliton solutions of the M-LSRI system by using the Hirota's direct method and explore its propagation dynamics. Also, we study the features of dark soliton collisions.

5 illus, 26 ref

000056   Dwivedi B N;Srivastava A K (Physics Dep, Indian Institute of Technology (Banaras Hindu Univ), Varanasi-221 005, Email: bholadwivedi@gmail.com) : Magnetic field in the gravitationally stratified coronal loops. J Astrophys Astr 2015, 36(1), 225-32.

Study the effect of gravitational stratification on the estimation of magnetic fields in the coronal loops. By using the method of MHD seismology of kink waves for the estimation of magnetic field of coronal loops, we derive a new formula for the magnetic field considering the effect of gravitational stratification. The fast-kink wave is a potential diagnostic tool for the estimation of magnetic field in fluxtubes. We consider the eleven kink oscillation cases observed by TRACE between July 1998 and June 2001. We calculate magnetic field in the stratified loops (B_str) and compare them with the previously calculated absolute magnetic field (B_abs). The gravitational stratification efficiently affects the magnetic field estimation in the coronal loops as it affects also the properties of kink waves. We find ≈22% increment in the magnetic field for the smallest (L = 72 Mm) while ≈ 42% increment in the absolute magnetic field for the longest (L = 406 Mm) coronal loops. The magnetic fields B_str and B_abs also increase with the number density, if the loop length does not vary much. The increment in the magnetic field due to gravitational stratification is small at the lower number densities, however, it is large at the higher number densities. We find that damping time of kink waves due to phase-mixing is less in the case of gravitationally stratified loops compared to nonstratified ones. This indicates the more rapid damping of kink waves in the stratified loops. In conclusion, we find that the gravitational stratification efficiently affects the estimation of magnetic field and damping time estimation especially in the longer coronal loops.

2 illus, 40 ref

000055   Cross M C;Kenig E;Allen J M A (Physics Dep, California Institute of Technology, Pasadena, California 91125, USA, Email: mcc@caltech.edu) : Building better oscillators using nonlinear dynamics and pattern formation. Pramana J Phys 2015, 84(3), 455-71.

Frequency and time references play an essential role in modern technology and in living systems. The precision of self-sustained oscillations is limited by the effects of noise, which becomes evermore important as the sizes of the devices become smaller. In this paper, we review our recent theoretical results on using nonlinear dynamics and pattern formation to reduce the effects of noise and improve the frequency precision of oscillators, with particular reference to ongoing experiments on oscillators based on nanomechanical resonators. We discuss using resonator nonlinearity, novel oscillator architectures and the synchronization of arrays of oscillators, to improve the frequency precision.

6 illus, 36 ref

000054   Carinena J F;Choudhury A G;Guha P (Fisica Teorica Dep, Universidad de Zaragoza, 50009 Zaragoza, Spain, Email: partha@bose.res.in) : Generalized virial theorem for the lienard-type systems. Pramana J Phys 2015, 84(3), 373-85.

A geometrical description of the virial theorem (VT) of statistical mechanics is presented using the symplectic formalism. The character of the Clausius virial function is determined for second-order differential equations of the Lienard type. The explicit dependence of the virial function on the Jacobi last multiplier is illustrated. The latter displays a dual role, namely, as a position-dependent mass term and as an appropriate measure in the geometrical context.

20 ref

000053   Balasubramanian K;Nair S S;Nagaraj N (Electronics and Communication Engineering Dep, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Amritapuri Campus, Clappana-690 525, Email: karthib@am.amrita.edu) : Classification of periodic, chaotic and random sequences using approximate entropy and lempel-ziv complexity measures. Pramana J Phys 2015, 84(3), 365-72.

Complexity' has several definitions in diverse fields. These measures are indicators of some aspects of the nature of the signal. Such measures are used to analyse and classify signals and as a signal diagnostics tool to distinguish between periodic, quasiperiodic, chaotic and random sig-nals. Lempel-Ziv (LZ) complexity and approximate entropy (ApEn) are such popular complexity measures that are widely used for characterizing biological signals also. In this paper, we compare the utility of ApEn, LZ complexities and Shannon's entropy in characterizing data from a nonlinear chaotic map (logistic map). In this work, we show that LZ and ApEn complexity measures can char-acterize the data complexities correctly for data sequences as short as 20 in length while Shannon's entropy fails for length less than 50. In the case of noisy sequences with 10% uniform noise, Shannon's entropy works only for lengths greater than 200 while LZ and ApEn are successful with sequences of lengths greater than 30 and 20, respectively.

6 illus, 3 tables, 10 ref

000052   Bafna M K;Sen P;Sen P K (Applied Physics Dep, Lakshmi Narain College of Technology, Indore, Email: mkbafna@gmail.com ) : Study of dipole moment calculations for various transitions on polarization state of output radiation. Indian J pure appl Phys 2015, 53(4), 221-4.

The electron and hole wave functions have been studied in the present paper using envelope function approximation. The hole Hamiltonian in a hexagonal crystal is obtained from the Luttinger Hamiltonian. The total angular momentum F and parity will be conserved leading to the mixing of states with same F value and equal parity. The values of dipole moments calculated for various transitions are discussed in the present paper. If a given transition is allowed in the dipole approximation with linearly polarized light, it cannot be allowed with circularly polarized light and vice-versa.

14 ref

023376   Virk H S (NO, , ) : Classical physics versus quantum physics: an overview. Omniscience 2014, 4(2), 36-42.

Newtonian mechanics is the foundation of Classical Physics. Newton's mechanics, Thermodynamics, Wave theory of Optics and Maxwell's electromagnetic theory belong to regime of Classical Physics and can be used to explain a wide range of phenomena in the Universe at macroscopic scale. These theories fail spectacularly when applied to phenomena in the atomic and nuclear regime, for example, proton-atom scattering or the flow of electrons in a semiconductor. Quantum mechanics is the most successful scientific theory that has ever been created and it has completely changed our view of the world. The failure of Classical Physics was highlighted by black body radiation and photoelectric effect. Max Planck and Albert Einstein provided explanations of both phenomena based on quantum hypothesis and are thus considered founders of Quantum Physics. The origin of quantum mechanics goes back to the mid-1920s. It was formulated first as matrix mechanics by Werner Heisenberg, Max Born and Pascual Jordan; then as wave mechanics by Louis de Broglie and Erwin Schrodinger; and later on as quantum statistics of subatomic particles by Fermi-Dirac and Bose-Einstein. Combining relativistic mechanics with quantum mechanics, Dirac formulated his relativistic quantum mechanics during 1930s. Uncertainty Principle is the cornerstone of Quantum Physics. The role of randomness in microscopic physical processes shatters the myth that the universe is deterministic. Quantum world is unpredictable in the classical sense and demolishes the idea of an objective universe. The Copenhagen interpretation remains the quantum mechanical formalism that is currently most widely accepted amongst physicists. Quantum theories support cosmic spirit pervading the cosmos and inter - relationship of individuals in the world society. Quantum philosophy is holistic and is going to revolutionize our world-view.

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023375   Sunil Kumar;Deo N (Physics Dep, Ramjas College, Delhi Univ, Delhi-110 007, Email: du.sunil@gmail.com) : Analysing correlations after the financial crisis of 2008 and multifractality in global financial time series. Pramana J Phys 2015, 84(2), 317-25.

Authors apply random matrix theory (RMT) to investigate the structure of cross-correlation in 20 global financial time series after the global financial crisis of 2008. We find that the largest eigenvalue deviates from the RMT prediction and is sensitive to the financial crisis. We find that the components of eigenvectors corresponding to the second largest eigenvalue changes sign in response to the crisis. We show that 20 global financial indices exhibit multifractality. We find that the origin of multifractality is due to the long-range correlations as well as broad probability function in the financial indices, with the exception of the index of Taiwan, as in all other indices the multifractal degree for shuffled and surrogate series is weaker than the original series. We fit the binomial multifractal model to the global financial indices.

2 illus, 1 table, 41 ref

023374   Nana Nbendjo B R;Enjieu Kadji H G;Cerdeira H A (Laboratory of Modelling and Simulation in Engineering and Biomimetics, Univ of Yaounde I, P.O. Box 812, Yaounde, Cameroon, Email: cerdeira@ift.unesp.br) : Synchronization enhancement via an oscillatory bath in a network of self-excited cells. Pramana J Phys 2015, 84(2), 257-72.

The possibility of using a dynamic environment to achieve and optimize phase synchronization in a network of self-excited cells with free-end boundary conditions is addressed in this paper. The dynamic environment is an oscillatory bath coupled linearly to a network of four cells. The boundaries of the stable solutions of the dynamical states as well as the ranges of coupling parameters leading to stability and instability of synchronization are determined. Numerical simulations are used to check the accuracy and to complement the result obtained from analytical treatment. The robustness of synchronization strategy is tested using a local and global injection of Gaussian white noise in the network. The control gain parameter of the bath coupling can modulate the occurrence of synchronization in the network without prior requirement of direct coupling among all the cells. The process of synchronization obtained through local injection is independent of the node at which noise is injected into the system. As compared to local injection, the global injection scheme increases the range of noise amplitude for which synchronization occurs in the network.

8 illus, 50 ref

023373   Kamal N K;Sinha S (NO, Institute of Mathematical Sciences, CIT Campus, Tharamani, Chennai-600 113, Email: neeraj@imsc.res.in) : Dynamic random links enhance diversity-induced coherence in strongly coupled neuronal systems. Pramana J Phys 2015, 84(2), 249-56.

Authors investigate the influence of diversity on the temporal regularity of spiking in a ring of coupled model neurons. We find diversity-induced coherence in the spike events, with an optimal amount of parametric heterogeneity at the nodal level yielding the greatest regularity in the spike train. Further, we investigate the system under random spatial connections, where the links are both dynamic and quenched, and in all the cases we observe marked diversity-induced coherence. We quantitatively find the effect of coupling strength and random rewiring probability, on the optimal coherence that can be achieved under diversity. Our results indicate that the largest coherence in the spike events emerge when the coupling strength is high, and when the underlying connections are mostly random and dynamically changing.

5 illus, 28 ref

023372   Kamal N K;Sharma P R;Shrimali M D (NO, The Institute of Mathematical Sciences, CIT Campus, Chennai-600 113, Email: m.shrimali@gmail.com) : Suppression of oscillations in mean-field diffusion. Pramana J Phys 2015, 84(2), 237-47.

Authors study the role of mean-field diffusive coupling on suppression of oscillations for systems of limit cycle oscillators. We show that this coupling scheme not only induces amplitude death (AD) but also oscillation death (OD) in coupled identical systems. The suppression of oscillations in the parameter space crucially depends on the value of mean-field diffusion parameter. It is also found that the transition from oscillatory solutions to OD in conjugate coupling case is different from the case when the coupling is through similar variable. We rationalize our study using linear stability analysis.

4 illus, 32 ref

023371   Jalan S (Complex Systems Lab, Discipline of Physics, Indian Institute of Technology Indore, IET-DAVV Campus, Khandawa Road, Indore-452 017, Email: sarikajalan9@gmail.com) : Importance of randomness in biological networks: a random matrix analysis. Pramana J Phys 2015, 84(2), 285-93.

Random matrix theory, initially proposed to understand the complex interactions in nuclear spectra, has demonstrated its success in diverse domains of science ranging from quantum chaos to galaxies. We demonstrate the applicability of random matrix theory for networks by providing a new dimension to complex systems research. We show that in spite of huge differences these interaction networks, representing real-world systems, posses from random matrix models, the spectral properties of the underlying matrices of these networks follow random matrix theory bringing them into the same universality class. We further demonstrate the importance of randomness in interactions for deducing crucial properties of the underlying system. This paper provides an overview of the importance of random matrix framework in complex systems research with biological systems as examples.

1 table, 47 ref

023370   Hens C R;Mishra A;Roy P K;Sen A;Dana S K (NO, CSIR-Indian Institute of Chemical Biology, Kolkata-700 032, Email: syamaldana@gmail.com) : Chimera states in a population of identical oscillators under planar cross-coupling. Pramana J Phys 2015, 84(2), 229-35.

Authors report the existence of chimera states in an assembly of identical nonlinear oscillators that are globally linked to each other in a simple planar cross-coupled form. The rotational symmetry breaking of the coupling term appears to be responsible for the emergence of these collective states that display a characteristic coexistence of coherent and incoherent behaviour. The finding, observed in both a collection of van der Pol oscillators and chaotic Rossler oscillators, further simplifies the existence criterion for chimeras, thereby broadens the range of their applicability to real-world situations.

4 illus, 27 ref

023369   Hasan S R;Prasad U;Nawnit Kumar;Ranjan R; Choudhary R N P (Physics Dep, D.A.C. College, Siwan, J.P. Univ, Bihar-841 226) : Investigation of impedance and electric modulus properties of bismuth layer-structured compound barium bismuth niobate. Int J latest Technol Engng Mgmt appl Sci 2015, 4(4), 51-4.

Barium bismuth niobate (BaBi₂Nb₂O₉: BBN), the ferroelectric compound of Aurivillius family, has been prepared through high-temperature mixed-oxide method. Using complex impedance spectroscopy (CIS) technique, real and imaginary parts of impedance (Z) and electric modulus (M) of the material were investigated within wide range of temperatures and frequencies. Impedance analysis indicates the presence of mostly bulk resistive (grain) contributions in the material which exhibits a decreasing tendency with the increase in temperature. It indicates negative temperature coefficient of resistance (NTCR) type behaviour of the material. Complex modulus plots indicate the presence of grain (bulk) along with grain boundary contributions in the material. It also supports the NTCR type behaviour of the material. Both the complex impedance and complex modulus plots indicate the presence of non-Debye type of relaxation in the material.

6 illus, 18 ref

023368   Choudhary A;Kohar V;Sinha S (NO, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, SAS Nagar, Sector 81, Manauli-140 306, Email: anshulheaven@gmail.com) : Preventing catastrophes in spatially extended systems through dynamic switching of random interactions. Pramana J Phys 2015, 84(2), 217-28.

In this paper, authors review and extend the results from our recently published work [Scientific Reports (Nature) 4, 4308] on taming explosive growth in spatially extended systems. Specifically, we consider collections of relaxation oscillators, which are relevant to modelling phenomena ranging from engineering to biology, under varying coupling topologies. We find that the system witnesses unbounded growth under regular connections on a ring, for sufficiently strong coupling strengths. However, when a fraction of the regular connections are dynamically rewired to random links, this blow-up is suppressed. We present the critical value of random links necessary for successful prevention of explosive growth in the oscillators for varying network rewiring time-scales. Further, we outline our analysis on the possible mechanisms behind the occurrence of catastrophes and how the switching of links helps to suppress them.

8 illus, 21 ref