011445   Bhatkar V B (NO, Shri Shivaji College, Akot-444 101, Email: bhatkar_vinod@hotmail.com) : Synhesis and photoluminescence characterization of Li_3xLa_1-xVO₃:Eu<. Bionano Front 2010, ICLAM(spl), 97-8.

Lanthanide vanadates and related compounds are of interest owing to their unusual magnetic characteristics and useful luminescent properties. This manuscript describes the synthesis of Li_3xLa_1-. _xVO₄:Eu^{3+ (x = 0.3) by citrate sol-gel and combustion method. The luminescence properties of this material are reported. The characteristic emission of Eu3+ could be observed in Li_0.9La_0.7VO₄:Eu3+. The intensity of the Li_0.9La_0.7VO₄:Eu3+ is nearly 50% as compared to that of YVO₄:Eu3+.}

2 illus, 1 table, 23 ref

011444   Bayrakceken F;Guney M;Tarhanci E (Optical Spectroscopy Div, Biomedical Engineering Dep, Yeditepe Univ, Istanbul, 34755, Turkey, Email: fubay@yeditepe.edu.tr) : Stokes and anti-stokes raman scattering of HITCI laser dye. Asian J Spectrosc 2009, 13(1-3), 15-20.

Optical response of organic laser-dyes is often discussed considering unfortunately only two electronic energy levels. In the simplest case, the excited state potential surface is displaced along a number of normal coordinates. Vibrations involved in optical dynamics appear as resonance and are also Raman active. A single spectral density suffices to describe optical two-level dynamics of rigid molecules. The high frequency part is hardly distinguishable from the resonance Raman spectrum including proper conversion factors. The low frequency part is difficult to measure by Raman spectroscopy, so femtosecond pump-probe and stimulated photon echo systems are better for structure elucidation.

5 illus, 17 ref

011443   Bayrakceken F (Biomedical Engineering Dep, Optical Spectroscopy Div, Yeditepe Univ, Istanbul, 34755, Turkey, Email: fubay@yeditepe.edu.tr) : Laser induced excited state propeties of 5H-dibenzo (a,d)cycloheptene in solution. Asian J Spectrosc 2009, 13(1-3), 9-14.

A number of photophysical properties of the title compound have been measured including the prompt fluorescence, B-type of delayed fluorescence, triplet-triplet absorption at room temperature, Raman scattering and phosphorescence at 77 K in methylcyclohexane. The quantum yield and decay parameters for the triplet state as a function of temperature have also been measured. The results are discussed and compared to those of molecules in similar structures. Raman lines were observed at 430 and 490 nm, with the Stokes and anti-Stokes shifts 30 nm, which were symmetrical around the peak of the phosphorescence at 460 nm.

6 illus, 1 table, 31 ref

011442   Bari R H;Ganesan V;Potadar S;Patil L A (P.G. Dep of Physics, Pratap College, Amalner-425 401, Email: plalchand_phy_aml@yahoo.co.in) : Structural, optical and electrical properties of chemically deposited copper selenide films. Bull Mater Sci 2009, 32(1), 37-42.

Stoichiometric and nonstoichiometric thin films of copper selenide have been prepared by chemical bath deposition technique at temperature below 60°C on glass substrate. The effect of nonstoichiometry on the optical, electrical and structural properties of the film was studied. The bandgap energy was observed to increase with the increase in at % of copper in composition. The grain size was also observed to increase with the decrease of at % of copper in composition. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), absorption spectroscopy, and AFM. The results are discussed and interpreted.

8 illus, 2 tables, 26 ref

011441   Bahari A;Eimeri R;Rasuli S;Farhang H;Fadaui M (Physics Dep, Faculty of Basic Science, Mazandaran Univ, P.O. Box 47416-1467, Babolsar, Iran, Email: alibahari@ymail.com) : Mechanical properties of single-walled carbon nanotubes by molecular mechanics model. Asian J Chem 2009, 21(2), 1600-8.

Many researchers have studied the mechanical properties of carbon nanotubes with various theoretical descriptions. There are still some discrepancies which need to further explore the mechanical properties of carbon nanotubes. The radial deformation is of significant interest in the analysis of nanotube-structural systems. Thus, the variation of mechanical properties was studied with tube diameter. In the present work, attention is paid to provide a very simple approach to formulate the radial deformation of single wall carbon nanotubes and derive in-plane stiffness in the hoop direction Y and Poisson ratio v_zθ of carbon nanotubes under radial pressure. It means that both Y and v_zθ are highly sensitive to tube diameter and decrease exponentially with increasing tube diameter but Y of zigzag is more sensitive to an increase in the tube diameter than armchair. The present developed analytical modeling approach predicts that Young modulus and Poisson ratio of single wall carbon nanotubes varies from 0.1 to 0.5 TPa and 0.6 to 1.9, respectively.

7 illus, 22 ref

011440   Babrerkar M K;Mane M L;Dhage V N;Shinde A B; Shukla S J;Jadhav K M (Physics Dep, Dr. Babasaheb Ambedkar Marathwada Univ, Aurangabad-431 004, Email: drkmjadhav@yahoo.com) : Synthesis and structural properties of nanosized cobalt ferrite thin film grown by spray pyrolysis technique. Bionano Front 2010, ICLAM(spl), 108-9.

Nanosized thin films of cobalt ferrite have been successfully grown by spray pyrolysis technique from aqueous solutions of CoSo₄ and FeCl₃ on a glass substrate. The influence of preparative parameter like substrate temperature on the CoFe₂O₄ films was studied. The uniformly deposited thin films were characterized by X-ray diffraction technique to confirm the presence of single phase structure. The improvement in crystallanity was obtained due to enhancement in substrate temperature. The lattice parameter increases with increases in substrate temperature.

2 illus, 1 table, 9 ref

011439   Babar A R;Shinde S S;Moholkar A V;Pawar S M; Bhosale C H;Kim J H;Rajpure K Y (Electrochemical Materials Laboratory, Physics Dep, Shivaji Univ, Kolhapur-416 004, Email: chb_phy@unishivaji.ac.in) : Structural and optical properties of antimony incorporated tin oxide thin films. Bionano Front 2010, ICLAM(spl), 116-18.

Thin films of undoped and antimony doped tin oxide (SnO₂ and Sb:SnO₂) prepared by spray pyrolysis technique with different antimony concentrations are found to be polycrystalline with tetragonal crystal structure, having preferential growth along the (211) and (112) planes. The compositional analysis and electronic behavior of Sb:SnO₂ thin films is studied by using the X-ray photoelectron spectroscopy. The direct optical band gap (E_g) has increased from 3.55 to 3.60 eV after Sb doping due to Moss- Burstein effect. The strong violet and comparatively weak red emissions are observed in room temperature PL. The origin of various peaks in PL spectra is assigned due to the combined effect of oxygen vacancies, tin interstitials or dangling bonds, singly charged oxygen vacancies, interstitial oxygen and crystal defects present in the films.

3 illus, 6 ref

011438   Ariponnammal S;Rathiha S K (Physics Dep, Gandhigram Rural Univ, Gandhigram-624 302, Email: arikumar67@yahoo.co.in) : Study of charge transfer in samarium sulphide (SmS). Asian J Spectrosc 2009, 13(1-3), 35-8.

The presence of charge transfer in SmS is analysed by experimental and theoretical X-ray powder diffraction (XRD) data. The direction and amount of charge transfer are inferred by plotting and comparing the structure factor of the components. Thus, a charge transfer of 0.23 electrons is obtained in SmS from samarium (Sm) to sulphur(S).

2 illus, 1 table, 125 ref

011437   Ariponnammal S;Arumugam S (Physics Dep, Gandhigram Rural Institute (Deemed Univ), Gandhigram-624 302, Email: arikumar67@yahoo.co.in) : FTIR spectroscopic analysis on dentrifrices. Asian J Spectrosc 2009, 13(1-3), 41-2.

The Fourier transform infra red spectroscopy (FTIR) analysis have been made on four commercially available dentrifrices.

2 illus, 1 table, 2 ref

011436   Amin M H;Mottalebizadeh A A;Borh S (NO, Materals and Energy Research Centre (MERC), Meshkin-Dasht Road, Karaj, Post Code: 3177983634, Iran, Email: doctoramin@gmail.com) : Effect of cyclotrimethylenetrinitramine on wet synthesis of ultra-nanocrystalline diamond. Asian J Chem 2009, 21(2), 1437-41.

The ultra-nanocrystalline diamond was synthesized by the detonation of a high explosive mixtures in water confinement. The presence of a diamond phase was revealed by X-ray diffraction and transmission electron microscopy. X-Ray line broadening was used to evaluate the peak profiles of diamond nanoparticles and their corresponding average crystallite sizes. The micro structure of nanocrystalline diamond have been investigated by high resolution transmission electron microscopy. The results indicate that the optimum of cyclotrimethylenetrinitramine addition on 2-methyl-1,3,5-trinitrobenzene is 60% and the size of nanodiamond particle was about 5 nm.

2 illus, 1 table, 14 ref

011435   Agrawal S;Srivastava S;Kumar S;Sharma S S; Tripathi B;Singh M;Vijay Y K (Physics Dep, Rajasthan Univ, Jaipur-302 004, Email: agrwl21@gmail.com) : Swift heavy ion irradiation effect on cu-doped CdS nanocrystals embedded in PMMA. Bull Mater Sci 2009, 32(6), 569-73.

Semiconductor nanocrystals (NCs) have received much interest for their optical and electronic properties. When these NCs dispersed in polymer matrix, brightness of the light emission is enhanced due to their quantum dot size. The CdCuS NCs have been synthesized by chemical route method and then dispersed in PMMA matrix. These nanocomposite polymer films were irradiated by swift heavy ion (SHI) (100 MeV, Si^{+7 ions beam) at different fluences of 1 x 1010 and 1 x 1012 ions/cm2 and then compared their structural and optical properties by XRD, atomic force microscopy, photoluminescence, and UV-Vis spectroscopy before and after irradiation. The XRD spectra showed a broad hump around 2θ ≈ 11-83° due to amorphous PMMA and other peaks corresponding to hexagonal structure of CdS nanocrystals in PMMA matrix. The photoluminescence spectra shows a broad peak at 530 nm corresponding to green emission due to Cu impurities in CdS. The UV-Vis measurement showed red shift in optical absorption and bandgap changed from 4-38-3-60 eV as the irradiation fluency increased with respect to pristine CdCuS nanocomposite polymer film.}

6 illus, 20 ref

010445   Wang B H;Wang W X (Modern Physics Dep, Science and Technology of China Univ, Hefei 230026, China, Email: bhwang@ustc.edu.cn) : Routing strategies in traffic network and phase transition in network traffic flow. Pramana J Phys 2008, 71(2), 353-58.

The dynamics of information traffic over scale-free networks has been investigated systematically. A series of routing strategies of data packets have been proposed, including the local routing strategy, the next-nearest-neighbour routing strategy, and the mixed routing strategy based on local static and dynamic information. The capacity of the network can be quantified by the phase transition from free flow state to congestion state. The optimal parameter values of each model leading to the highest efficiency of scale-free networked traffic systems have been found. Moreover, we have found hysteretic loop in networked traffic systems with finite packets delivering ability. Such hysteretic loop indicates the existence of the bi-stable state in the traffic dynamics over scale-free networks.

2 illus, 7 ref

010444   Suguna C;Sinha S (Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad-500 007, Email: suguna@ccmb.res.in) : Synchronization in multicell systems exhibiting dynamic plasticity. Pramana J Phys 2008, 71(2), 423-35.

Collective behaviour in multicell systems arises from exchange of chemicals/signals between cells and may be different from their intrinsic behaviour. These chemicals are products of regulated networks of biochemical pathways that underlie cellular functions, and can exhibit a variety of dynamics arising from the non-linearity of the reaction processes. We have addressed the emergent synchronization properties of a ring of cells, diffusively coupled by the end product of an intracellular model biochemical pathway exhibiting non-robust birhythmic behaviour. The aim is to examine the role of intercellular interaction in stabilizing the non-robust dynamics in the emergent collective behaviour in the ring of cells. We show that, irrespective of the inherent frequencies of individual cells, depending on the coupling strength, the collective behaviour does synchronize to only one type of oscillations above a threshold number of cells. Using two perturbation analyses, we also show that this emergent synchronized dynamical state is fairly robust under external perturbations. Thus, the inherent plasticity in the oscillatory phenotypes in these model cells may get suppressed to exhibit collective dynamics of a single type in a multicell system, but environmental influences can sometimes expose this underlying plasticity in its collective dynamics.

8 illus, 42 ref

010443   Stella A L;Baldovin F (Dipartimento di Fisica and Sezione INFN, Universita di Padova, Via Marzolo 8, I-35131 Padova, Italy, Email: attilio.stella@pd.infn.it) : Role of scaling in the statistical modelling of finance. Pramana J Phys 2008, 71(2), 341-52.

Modelling the evolution of a financial index as a stochastic process is a problem awaiting a full, satisfactory solution since it was first formulated by Bachelier in 1900. Here it is shown that the scaling with time of the return probability density function sampled from the historical series suggests a successful model. The resulting stochastic process is a heteroskedastic, non-Markovian martingale, which can be used to simulate index evolution on the basis of an autoregressive strategy. Results are fully consistent with volatility clustering and with the multiscaling properties of the return distribution. The idea of basing the process construction on scaling, and the construction itself, are closely inspired by the probabilistic renormalization group approach of statistical mechanics and by a recent formulation of the central limit theorem for sums of strongly correlated random variables.

5 illus, 23 ref

010442   Singh A R;Giri D;Kumar S (Physics Dep, Banaras Hindu Univ, Varanasi-221 005, Email: yashankit@yahoo.com) : Conformational properties of polymers. Pramana J Phys 2008, 71(2), 283-95.

Discusses exact enumeration technique and its application to polymers and biopolymers. Using this method one can obtain phase diagram in thermodynamic limit. The method works quite well in describing the outcomes of single molecule force spec-troscopy results where finite size effects play a crucial role.

8 illus, 49 ref

010441   Shukla P (Physics Dep, North Eastern Hill Univ, Shillong-793 022, Email: shukla@nehu.ac.in) : Dynamics of bootstrap percolation. Pramana J Phys 2008, 71(2), 319-29.

Bootstrap percolation transition may be first order or second order, or if, may have a mixed character where a first-order drop in the order parameter is preceded by critical fluctuations. Recent studies have indicated that the mixed transition is characterized by power-law avalanches, while the continuous transition is characterized by truncated avalanches in a related sequential bootstrap process. We explain this behaviour on the basis of an analytical and numerical study of the avalanche distributions on a Bethe lattice.

2 illus, 8 ref

010440   Sen P (Physics Dep, Calcutta Univ, 92 Acharya Prafulla Chandra Road, Kolkata-700 009, Email: psphy@caluniv.ac.in ) : Realistic searches on stretched exponential networks. Pramana J Phys 2008, 71(2), 313-17.

Considers navigation or search schemes on networks which have a degree distribution of the form P(k) ∝ exp( - k^γ). In addition, the linking probability is taken to be dependent on social distances and is governed by a parameter λ. The searches are realistic in the sense that not all search chains can be completed. An estimate of μ = ρ/Sd, where ρ is the success rate and s_d the dynamic path length, shows that for a network of N nodes, μ ∝ N^-δ in general. Dynamic small world effect, i.e., δ ≈ 0 is shown to exist in a restricted region of the λ-γ plane.

3 illus, 21 ref

010439   Saha A;Chakravarty S;Bhattacharjee J (NO, S.N. Bose National Centre for Basic Sciences, JD-Block, Sector-III, Salt Lake City, Kolkata-700 098, Email: arnab@bose.res.in) : Dominance of rare events in some problems in statistical physics. Pramana J Phys 2008, 71(2), 413-22.

Shows how the theory of large deviations in the coin toss experiment can give some insight into nonequilibrium fluctuation theorems and intermittency in turbulence.

3 illus, 26 ref

010438   Reenbohn W L;Saikia S;Roy R;Mahato M C (Physics Dep, North-Eastern Hill Univ, Shillong-793 022, Email: mcmangal@yahoo.com) : Motional dispersions and ratchet effect in inertial systems. Pramana J Phys 2008, 71(2), 297-306.

Obtain ratchet effect in inertial structureless systems in symmetric periodic potentials where the asymmetry comes from the non-uniform friction offered by the medium and driven by symmetric periodic forces. In the adiabatic limit the calculations are done by extending the matrix continued fraction method and also by numerically solving the appropriate Langevin equation. For finite frequency field drive the ratchet effect is obtained only numerically. In the transient time scales the system shows dispersionless behaviour as reported earlier when a constant force is applied. In the periodic drive case the dispersion behaviour is more complex. In this brief communication authour report some of the results of the work.

7 illus, 13 ref

010437   Mukherjee V;Divakaran U;Dutta A;Sen D (Physics Dep, Indian Institute of Technology, Kanpur-208 016, Email: victor@iitk.ac.in) : Quenching dynamics of a quantum XY spin-1/2 chain in the presence of transverse field by the application of a generalized Landau-Zener formula. Pramana J Phys 2008, 71(2), 403-12.

Review the quenching dynamics of a quantum XY spin-1/2 chain in the presence of a transverse field, when the transverse field or the anisotropic interaction is quenched at a slow but uniform rate. We also extend the results to the cases in which the system starts with any arbitrary initial condition as opposed to the initial fully magnetically aligned state which has been extensively studied earlier. The evolution is non-adiabatic in the time interval when the parameters are close to their critical values, and is adiabatic otherwise. The density of defects produced due to non-adiabatic transitions is calculated by mapping the many-particle system to an equivalent Landau-Zener problem. We show that in one dimension the density of defects in the final state scales as 1/√τ irrespective of the initial condition, where τ is the quenching time-scale. However, the magnitude of density of defects is found to depend on the initial condition.

4 illus, 28 ref

010436   Ghosh S K;Sain A (Physics Dep, Indian Institute of Technology Bombay, Mumbai-400 076, Email: surya@phy.iitb.ac.in) : Statistical properties of curved polymer. Pramana J Phys 2008, 71(2), 385-89.

Intrinsic curvature of biopolymers is emerging as an essential feature in various biological phenomena. Examples of polymers with intrinsic curvature are microtubule in eukaryotic cells or FtsZ filaments in prokaryotic cells. We consider the general model for polymers with intrinsic curvature. We aim to study both equilibrium and dynamic properties of such polymers. Here we report preliminary results on the equilibrium distribution function P(R) of the end-to-end distance R. We employ transfer matrix method for this study.

3 illu, 6 ref

010435   Ghosh B;Sain A (Physics Dep, Indian Institute of Technology Bombay, Powai, Mumbai-400 076, Email: asain@phy.iitb.ac.in) : Polymerization-depolymerization model for generation of contractile force during bacterial cell division. Pramana J Phys 2008, 71(2), 307-11.

During the last phase of cell division in bacteria, a polymeric ring forms at the division site. The ring, made of intracellular proteins, anchors to the cell wall and starts to contract. That initiates a dividing septum to close in, like the shutter of a camera, eventually guillotining the cell into two daughters. All through, the ring remains at the leading edge of the septum and seems to power its closure. It is not understood why does the ring contract. We propose a theoretical model to explain this. It is worth mentioning that a similar contraction phenomenon occurs for the actin ring in eukaryotes, but there it is due to motor proteins, which however, are absent in bacteria.

2 illus, 10 ref

010434   George S;Nampoori V P N (International School of Photonics, Cochin Univ of Science and Technology, Cochin-22) : Imaging diagnostics using ICCD frame photography for the study of the expansion dynamics of laser-blow-off plasma plume. Sci Soc 2008, 6(2), 161-66.

Plasma imaging diagnostics with fast photography to study the expansion dynamics of laser blow-off (LBO) plasma plume under the influence of different ambient gas has developed. The dynamics of plasma plume formation by the laser-blow-off (LBO) of multi-component LIF-C thin film recorded and analyzed. At vacuum, the plume shape has ellipsoidal shape and upon increase in ambient gas pressure, sharp plume boundary is developed showing a new phenomena of focusing (confinement in lateral space) like behavior in the front end, which persists for long time.

3 illus, 4 tables, 14 ref

010433   Filoche M;Sapoval B (Physique de la Matiere Condensee, Ecole Polytechnique, CNRS, 91128 Palaiseau, France, Email: marcel.filoche@polytechnique.edu) : Diffusion of gases into the lung: how physics can help to understand physiology. Pramana J Phys 2008, 71(2), 245-51.

In the human lung, the gas transfer between air and blood is achieved in terminal units that are called 'acini'. Whereas convection is still the predominant transport phenomenon at the acinus entrance, most of the acinar surface is in fact accessed by diffusion. The transition between convection and diffusion, and thus the size of the diffusion unit, depends on the air velocity at the acinus entrance. In this paper, we present a gas transport model which takes into account both the diffusion into the acinus and the diffusion across the alveolar membrane. It is shown that the physiological sizes of the diffusion unit in the lung, at rest or at exercise, can be explained by physical arguments. In that sense, diffusion is the 'dimensioning criterion' of the lung at the acinar level. This approach shows that, due to diffusional screening at inspiration and at rest, there exists a permanent spatial inhomogeneity of oxygen and carbon dioxide partial pressure which reduces the effective surface efficiency of the human acinus to a value of only 30 to 40%. This model casts a new light on the properties of this physiological transport system. It permits in particular to understand how several diseases among which pulmonary edema may remain asymptomatic in their early stages.

5 illus, 9 ref

010432   Dey D;Islam M N;Hussain S A;Bhattacharjee D (Physics Dep, Tripura Univ, Suryamaninagar-799 130, Email: md_nurulislam@rediffmail.com) : Photophysical characterization of layer-by-layer self-assembled films of deoxyribonucleic acid. Pramana J Phys 2008, 71(2), 379-84.

Reports the photophysical characterization of self-assembled layer-by-layer (LbL) films of DNA (deoxyribonucleic acid) fabricated at different temperatures by electrostatic interaction with a polycation, poly(allylamine hy-drochloride). It was observed that there was a successful incorporation of DNA molecules in DNA-PAH LbL films at room temperature as well as after melting temperature. An abrupt increase in intensity was observed in the absorption spectra of the films fabricated at high temperature which is an indication of the immobilization of unzipped DNA after melting of DNA. The films were observed to remain unaffected even after 250 h of film fabrication. The total electrostatic interaction time between DNA and PAH is about 15 min, that is, no PAH binding site is free.

5 illus, 11 ref

010431   Chakraborti A;Patriarca M (Physics Dep, Banaras Hindu Univ, Varanasi-221 005, Email: achakraborti@yahoo.com) : Gamma-distribution and weath inequality. Pramana J Phys 2008, 71(2), 233-43.

Discuss the equivalence between kinetic wealth-exchange models, in which agents exchange wealth during trades, and mechanical models of particles, exchanging energy during collisions. The universality of the underlying dynamics is shown both through a variational approach based on the minimization of the Boltzmann entropy and a microscopic analysis of the collision dynamics of molecules in a gas. In various relevant cases, the equilibrium distribution is well-approximated by a gamma-distribution with suitably defined temperature and number of dimensions. This in turn allows one to quantify the inequalities observed in the wealth distributions and suggests that their origin should be traced back to very general underlying mechanisms, for instance, the fact that smaller the fraction of the relevant quantity (e.g. wealth) that agent can exchange during an interaction, the closer the corresponding equilibrium distribution is to a fair distribution.

1 illus, 22 ref

010430   Chakrabarti B K;Chatterjee A;Bhattacharyya P (Theoretical Condensed Matter Physics Div and Centre for Applied Mathem, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700 064, Email: bikask.chakrabarti@saha.ac.in) : Two-fractal overlap time series: earthquakes and market crashes. Pramana J Phys 2008, 71(2), 203-10.

Finds prominent similarities in the features of the time series for the (model earthquakes or) overlap of two Cantor sets when one set moves with uniform relative velocity over the other and time series of stock prices. An anticipation method for some of the crashes have been proposed here, based on these observations.

5 illus, 11 ref

010429   Benoy M D;Suresh Babu M;Mohammed E M (Physics Dep, M.A. College, Kothamangalam, Kerala-686 691, Email: benoydas@yahoo.co.uk) : Lead selenide (PbSe) films prepared by reactive evaporation. Sci Soc 2008, 6(2), 187-90.

Polycrystalline lead selenide films (PbSe) have been prepared by reactive thermal evaporation, at different substrate temperature. Polycrystalline films were obtained at substrate temperature 373K. The films were identified by X-ray diffraction.

1 illus, 1 table, 8 ref

010428   Amritkar R E (NO, Physical Research Laboratory, Navrangapura, Ahmedabad-380 009, Email: amritkar@prl.ernet.in ) : Synchronization of networks. Pramana J Phys 2008, 71(2), 195-201.

The synchronization of coupled dynamical systems on networks. The dynamics is governed by a local nonlinear oscillator for each node of the network and interactions connecting different nodes via the links of the network. We consider existence and stability conditions for both single- and multi-cluster synchronization. For networks with time-varying topology we compare the synchronization properties of these networks with the corresponding time-average network. Finds that if the different coupling matrices corresponding to the time-varying networks commute with each other then the stability of the synchronized state for both the time-varying and the time-average topologies are approximately the same. On the other hand, for non-commuting coupling matrices the stability of the synchronized state for the time-varying topology is in general better than the time-average topology.

2 illus, 14 ref

009537   Zeng X X;Hou J S;Yang S Z (Institute of Theoretical Physics, China West Normal Univ, Nanchang, 637002, Sichuan, People's Republic of China, Email: xxzengphysics@163.com) : Remarks on hawking radiation as tunneling from a uniformly accelerating black hole. Pramana J Phys 2008, 70(3), 409-15.

Motivated by the Ilaniilton-Jacobi method of Angheben et al, we investigate the Hawking tunneling radiation from a uniformly accelerating rectilinear black hole for which the horizons and entropy are functions of 0. After several coordinate transformations, we conclude that when the self-gravitational interaction and energy conservation are taken into account, the actual radiation spectrum deviates from the thermal one and the tunneling rate is the function of 9 though it is still related to the change of the Bekenstein-Hawking entropy.

27 ref

009536   Zemanova L;Lopez G Z;Zhou C;Kurths J (Institute of Physics, Potsdam Univ, 14469 Potsdam, Germany, Email: cszhou@hkbu.edu.hk) : Complex brain networks: from topological communities to clustered dynamics. Pramana J Phys 2008, 70(6), 1087-97.

Recent research has revealed a rich and complicated network topology in the cortical connectivity of mammalian brains. A challenging task is to understand the implications of such network structures on the functional organisation of the brain activities. We investigate synchronisation dynamics on the corticocortical network of the cat by modelling each node of the network (cortical area) with a subnetwork of interacting excitable neurons. We find that this network of networks displays clustered synchronisation behaviour and the dynamical clusters closely coincide with the topological community, structures observed in the anatomical network. The correlation between the firing rate of the areas and the areal intensity is additionally examined. Our results provide insights into the relationship between the global organisation and the functional specialisation of the brain cortex.

8 illus, 14 ref

009535   Zaccai J (NO, Institut Laue Langevin, Grenoble, France, Email: zaccai@ill.fr) : Life at extreme conditions : neutron scattering studies of biological molecules suggest that evolution selected dynamics. Pramana J Phys 2008, 71(4), 739-43.

Review concentrates on recent work performed at the neutrons in biology laboratories of the Institut Laue Langevin and Institut de Biologie Structurale in Grenoble. Extremophile organisms have been discovered that require extreme conditions of temperature, pressure or solvent environment for survival. The existence of such organisms poses a significant challenge in understanding the physical chemistry of their proteins, in view of the great sensitivity of protein structure and stability to the aqueous environment and to external conditions in general. Results of neutron scattering measurements on the dynamics of proteins from extremophile organisms, in vitro as well as in vivo, indicated remarkably how adaptation to extreme conditions involves forces and fluctuation amplitudes that have been selected specifically, suggesting that evolutionary macromolecular selection proceeded via dynamics. The experiments were performed on a halophilic protein, and membrane adapted to high salt, a thermophilic enzyme adapted to high temperature and its mesophilic (adapted to 37° C) homologue; and in vivo for psy-chrophilic, mesophilic, thermophilic and hyperthermophilic bacteria, adapted respectively to temperatures of 4°C, 37°C, 75°C and 85°C. Further work demonstrated the existence of a water component of exceptionally low mobility in an extreme halophile from the Dead Sea, which is not present in mesophile bacterial cells.

12 ref

009534   Yusuf S M (Soild State Physics Div, Bhabha Atomic Recsearch Center, Mumabi-400 085, Email: smyusuf@barc.gov.in) : Magnetic correlations in oxides : neutron diffraction and neutron depolarization study. Pramana J Phys 2008, 71(4), 695-704.

Studied magnetic correlations in several oxide materials that belong to colossal magnetoresistive, naturally occurring layered oxide showing low-dimensional magnetic ordering, solid oxide fuel cell interconnect materials, and magnetic nanoparti-cles using neutron diffraction and neutron depolarization techniques. In this paper, an overview of some of these results is given.

8 illus, 1 table, 10 ref

009533   Yadav V K;Sathyanarayana K;Bora D (NO, Institute for Plasma Research, Bhat, Gandhinagar-382 428, Email: vipin@csp.res.in) : Electron cyclotron resonance breakdown studies in a linear plasma system. Pramana J Phys 2008, 70(3), 487-501.

Electron cyclotron resonance (ECR) plasma breakdown is studied in a small linear cylindrical system with four different gases - hydrogen, helium, argon and nitrogen. Microwave power in the experimental system is delivered by a magnetron at 2.45 ± 0.02 GHz in TEio mode and launched radially to have extra-ordinary (X) wave in plasma. The axial magnetic field required for ECR in the system is such that the fundamental ECR surface (B - 875.0 G) resides at the geometrical centre of the plasma system. ECR breakdown parameters such as plasma delay time and plasma decay time from plasma density measurements are carried out at the centre using a Langmuir probe. The operating parameters such as working gas pressure (1 x 10^{-5-1 x 10-2 mbar) and input microwave power (160-800 W) are varied and the corresponding effect on the breakdown parameters is studied. The experimental results obtained are presented in this paper.}

18 illus, 1 table, 23 ref

009532   Wei L H;Wu S Y;Zhang Z H;Wang X F;Hu Y X (Aplied Physics Dep, Electronic Science and Technology of China, Chengdu 610054, People's Republic of China, Email: shaoyi_wu163.com) : Investigations on the local structure and g factors for the interstitial Ti<. Pramana J Phys 2008, 71(1), 167-73.

The EPR g factors g_i (i = x, y, z) for the interstitial Ti³⁺ in rutile are theoretically studied from the perturbation formulas of these parameters for a 3d¹ ion in rhombically compressed octahedra. The ligand octahedron in the impurity center is found to be less compressed than that on the host interstitial site due to the Jahn-Teller effect. The local compression parameter (≈ 0.026) and the rhombic distortion angle δφ' (≈ 0.7°) around the impurity Ti³⁺ are smaller than the host values (≈ 0.091 and 3.5°). The theoretical g factors based on the above local structural parameters are in good agreement with the experimental data. In addition, the g factors for a tetragonal interstitial Ti³⁺ center are also reasonably interpreted.

1 table, 32 ref

009531   Wagh A G (86 Dhruva, Bhabha Atomic Research Centre, Mumbai-400 085, Email: nintsspd@barc.gov.in) : In the wonderland of ultra-parallel neutron beams. Pramana J Phys 2008, 71(4), 797-807.

Bragg reflections from single crystals yield angular widths of a few arcsec for thermal neutron beams. The Bonse-Hart proposal to attain a sharp, nearly rectangular profile by Bragg reflecting neutrons multiply from a channel-cut single crystal, was realized in its totality three and a half decades later by achieving the corresponding Darwin reflection curves for 5.23 A neutrons. This facilitated SUSANS (Super USANS) measurements in the Q ~ 10^{-5 Angustrum-1 range. The polarized neutron option was introduced into the SUSANS set-up by separating the up- and down-spin neutron beams by ~10 arcsec with a magnetic (air) prism. The neutron angular width has recently been reduced further by an order of magnitude to ~0.6 arcsec by diffracting 5.3 A neutrons from a judiciously optimized Bragg prism. This constitutes the most parallel monochromatic neutron beam produced to date. I present the first SUSANS spectra probing the Q ~ 10-6 A-1 domain, recorded with this beam.}

15 illus, 15 ref

009530   Wadhawan V K (Raja Ramanna Fellow (DAE), Solid State hysics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: vkw1412@gmail.com) : Complex systems: an introduction, Anthropic principle, terrestrial complexity, complex materials. Resonance 2009, 14(9), 894-906.

In Part 1 of this article (Resonance, August 2009) we introduced information theory and chaos theory, and discussed the computational nature of all phenomena, complex or simple. In this concluding part, we further emphasize the fact that the degree of complexity of a system depends in an important way on our perspective and prior understanding of the system. This anthropocentric aspect of complexity is exemplified in a dramatic way by the anthropic principle. This is followed by a description of the evolution of complexity in our ecosphere. Complexity in some 'nonadaptive' complex systems, namely complex materials, is also described briefly.

2 illus, 21 ref

009529   Vyas V (Thermo-acoustics Research Lab, Chemistry Dep, Allahabad Univ, Allahabad-211 002, Email: vimlavyas@rediffmail.com) : Speeds of sound and isothermal compressibility of ternary liquid systems: application of Flory's statistical theory and hard sphere models. Pramana J Phys 2008, 70(4), 731-38.

Speeds of sound and densities of three ternary liquid systems namely, toluene + n-heptane + n-hexane (I), cyclohexane + n-heptane + n-hexane (II) and n-hexane + n-heptane + n-decane (III) have been measured as a function of the composition at 298.15 K at atmospheric pressure. The experimental isothermal compressibility has been evaluated from measured values of speeds of sound and density. The isothermal compressibility of these mixtures has also been computed theoretically using different models for hard sphere equations of state and Flory's statistical theory. Computed values of isothermal compressibility have been compared with experimental findings. A satisfactory agreement has been observed. The superiority of Flory's statistical theory has been established quite reasonably over hard sphere models.

6 tables, 23 ref

009528   Varghese T;Balakrishna K M (Physics Dep, Nirmala College, Muvattupuzha, Kerela-686 661, Email: ptvarghese07@yahoo.co.in) : Electron momentum distribution of silver. Sci Soc 2009, 6(1), 33-6.

Electron momentum distribution and Compton profiles of Ag has been measured using HPGe photon detector. The target atoms were excited by means of 59.54 keV gamma ray photons from Am-241. The measurements were carried out on a high purity thin elemental foil. The data were recorded and analyzed in a 4K multichannel analyzer. These data duly corrected for instrumental resolution effects, sample absorptiori energy dependence of the differential Compton cross-section and double scattering, and compared with theoretical RFA values.

1 illus, 1 table, 7 ref

009527   Vani V C;Chatterjee S (Instrumentation Dep, Indian Institute of Science, Bangalore-560 012, Email: vani@isu.iisc.ernet.in) : Scattering of light by a periodic structure in the presence of randomness. VII. Application of statistical detection test. Pramana J Phys 2008, 70(5), 875-86.

Detection of periodic structures, hidden in random surfaces has been addressed by us for some time and the 'extended matched filter' method, developed by us, has been shown to be effective in detecting the hidden periodic part from the light scattering data in circumstances where conventional data analysis methods cannot reveal the successive peaks due to scattering by the periodic part of the surface. It has been shown that if τ₀ is the coherence length of light on scattering from the rough part and A is the wavelength of the periodic part of the surface, the extended matched filter method can detect hidden periodic structures for (τ₀/Λ) > 0.11, while conventional methods are limited to much higher values ((τ₀/Λ) ≥ 0.33). In the method developed till now, the detection of periodic structures involves the detection of the central peak, first peak and second peak in the scattered intensity of light, located at scattering wave vectors v_x =0, Q, 2Q, respectively, where Q = 2πTr/Λ, their distinct identities being obfuscated by the fact that the peaks have width Δv_x = 2π/τ₀ >> Q. The relative magnitudes of these peaks and the consequent problems associated in identifying them is discussed. The Kolmogorov-Smirnov statistical goodness test is used to justify the identification of the peaks. This test is used to 'reject' or 'not reject' the null hypothesis which states that the successive peaks do exist. This test is repeated for various values of τ₀/Λ, which leads to the conclusion that there is really a periodic structure hidden behind the random surface.

4 illus, 1 table, 14 ref

009526   Tun Z;Noel J J;Shoesmith D W (Canadian Neutron Beam Centre, National Research Council Canada, Chalk River, Ontario, Canada K0J 1J0, Email: zin.tun@nrc.gc.ca) : Anodic oxide growht on Zr in neutral aqueous solution. Pramana J Phys 2008, 71(4), 769-76.

Anodization and subsequent cathodic reactions on a thin-film sample of Zr were studied with in-situ neutron reflectometry (NR) and electrochemical impedance spectroscopy (EIS). The NR results during anodization showed the originally 485 A thick Zr film generally behaved similar to a bulk electrode in neutral solution. The anodization ratio measured at applied potentials increased in steps of 0.5 V was somewhat higher than the value determined by coulometry, while the Pilling Bedworth ratio is in good agreement with published data. Thickening of the oxide layer, accelerated immediately after each potential increase, gradually decreased over several hours, but remained nonzero even after ~12 h. The thickened oxide eventually cracked when its thickness reached ~120 Angustrum, causing loss of passivation. Surprisingly, neither the anodization ratio nor the Pilling Bedworth ratio showed any discontinuity at the time of oxide cracking, and the EIS behaviour remained qualitatively as before. This observation is taken as the evidence that the cracked and intact regions of the electrode behave more or less independently as parallel electrodes. When the potential was eventually switched to cathodic polarity, NR shows, as expected, that the effects of oxide cracking were irreversible. However, the electrode resistance recovered partially suggesting the cracks were rapidly plugged with newly formed oxide.

7 illus, 5 ref

009525   Tomkinson J (The ISIS Facilty, The Rutherford Appleton Laboratory, The Science and Technology, Facili, Chilton, Didcot, OX11 OQX, UK, Email: j.tomkinson@rl.ac.uk) : Analysis of inelastic neutron scattering results on model compounds of the nitrogenous bases of the nucleotides. Pramana J Phys 2008, 71(4), 745-54.

The role that model compounds can play in understanding the vibrational eigenvectors of molecules is discussed. Assigning the spectra of model compounds is of particular importance and the individual-scaling approach, that has been used with isolated molecule ab-initio calculations, is outlined. Special emphasis is given to recent work on assigning the spectra of three 5-6 heterobicyclic systems; indole, benzimidazole and isatin.

7 illus, 1 table, 11 ref

009524   Tiwari Y N (Physics Dep, North-Eastern Hill Univ, Shillong-793 022, Email: yntiwari@gmail.com) : Formation of H-atom in 2s excited state of proton-lithium and proton-sodium scatering. Pramana J Phys 2008, 70(4), 753-58.

The differential and total cross-sections have been investigated in the formation of H-atom in the 2s excited state of proton-lithium and proton-sodium scattering by using the Coulomb projected Born (CPB) approximation in the energy range from 50 to 10,000 keV. The results thus obtained are compared with the available results and found to be in reasonable agreement.

3 illus, 1 table, 15 ref

009523   Tirasoglu E;Sogut O (Physics Dep, Faculty of Arts and Sciences, Karadeniz Technical Univ, Trabzom, Turkey, Email: omer_sogut@yahoo.com) : Determination of experimental K-shell fluorescence yield for potassium and calcium compounds. Pramana J Phys 2008, 70(3), 471-7.

K-shell fluorescence yields were experimentally determined for potassium and calcium compounds using a Si(Li) X-ray detector system (FWHM=5.96 keV at 160 eV). The samples were excited by 5.96 keV photons produced by a ^{55Fe radioisotope source. The experimental values are systematically lower than the theoretical values.}

4 illus, 1 table, 19 ref

009522   Thyagu N N;Gupte N (Physics Dep, Indian Institute of Technology Madras, Chennai-600 036, Email: nirmal@physics.iitm.ac.in) : Crisis and unstable dimension variability in the bailout embedding map. Pramana J Phys 2008, 70(6), 1031-7.

The dynamics of inertial particles in 2-d incompressible flows can be modeled by 4-d bailout embedding maps. The density of the inertial particles, relative to the density of the fluid, is a crucial parameter which controls the dynamical behaviour of the particles. We study here the dynamical behaviour of aerosols, i.e. particles heavier than the flow. An attractor widening and merging crisis is seen in the phase space in the aerosol case. Crisis-induced intermittency is seen in the time series and the laminar length distribution of times before bursts give rise to a power law with the exponent β = - 1/3. The maximum Lyapunov exponent near the crisis fluctuates around zero indicating unstable dimension variability (UDV) in the system. The presence of unstable dimension variability is confirmed by the behaviour of the probability distributions of the finite time Lyapunov exponents.

4 illus, 9 ref

009521   Teixeira J (Laboratoire Leon Brillouin (CEA/CNRS), CEA Saclay 91191, Gif-sur-Yvette Cedex, France, Email: jose.teixeira@cea.fr) : Dynamics of hydrogen bonds in water and consequences for the unusual behaviour of supercooled water. Pramana J Phys 2008, 71(4), 761-8.

The dynamics of liquid water is evaluated by the coherent quasi-elastic scattering at two different momentum transfers, in order to discriminate hydrogen bond lifetime from molecular dynamics. The results indicate a possible issue for the puzzle of the behaviour of supercooled water.

3 illus, 18 ref

009520   Tadic B;Levnajic Z (Theoretical Physics Dep, Jozef Stefan Institute, Box 3000 SI-1001 Ljubjana, Slovenia, Email: Bosilijka.Tadic@ijs.si) : Robust dynamical effects in traffic and chaotic maps on trees. Pramana J Phys 2008, 70(6), 1099-1108.

In the dynamic processes on networks collective effects emerge due to the couplings between nodes, where the network structure may play an important role. Interaction along many network links in the nonlinear dynamics may lead to a kind of chaotic collective behavior. Here we study two types of well-defined diffusive dynamics on scale-free trees: traffic of packets as navigated random walks, and chaotic standard maps coupled along the network links. We show that in both cases robust collective dynamic effects appear, which can be measured statistically and related to non-ergodicity of the dynamics on the network. Specifically, we find universal features in the fluctuations of time series and appropriately defined return-time statistics.

6 illus, 19 ref

009519   Suresh Babu M;Binu P J;Benoy M D;Thankachan S (Physics Dep, Maharaja's College, Ernakulam, Kerala-682 001, Email: emmohammed_2005@yahoo.com) : New experimental setup for measuring magnetostriction. Sci Soc 2009, 7(1), 85-8.

One of the interesting phenomena associated with the ferro and ferri magnetic materials are their magnetostriction. That is, these materials undergo a change in dimensions when their state of magnetization is changed by an applied magnetic field. This paper describes one of the experimental setup for the accurate measurement of magnetostriction. We measured magnetostriction of polycrystalline NiFe₂O₄ samples with this setup and the results are in good agreement with the standard values. This setup may be modified to be used as an optical modulator. Scope exists to continue research using this setup to study the magnetostriction of different materials and to develop new devices for optical communication.

2 illus, 4 ref

009518   Sudha Singh;Sinha A (Physics Dep, Ranchi Univ, Ranchi-834 008, Email: vasudha_rnc1@rediffmail.com) : Solutions of two-mode Jaynes-Cummings models. Pramana J Phys 2008, 70(5), 887-900.

A simple procedure to solve two fully quantized non-linear Jaynes-Cummings models is presented, one in which an atom interacts with a two-mode radiation field in a Raman-type process and the other involving multiphoton interaction between the two-mode field and the atom. Effect of intensity-dependent coupling between the field and the atom in both the above-mentioned cases has also been investigated. The unitary transformation method presented here not only solves the time-dependent problem but also permits a determination of the eigensolutions of the interacting Hamiltonian at the same time. Graphical features of the time dependence of the population inversion have been analysed when one of the field modes is prepared initially in a coherent state while the other one in a vacuum state.

2 illus, 25 ref

009517   Sudha G F;Santosh Kumar M;Swetha V;Gobinath N (Electronics and Communication Engg Dep, Pondicherry Engineering College, Pondicherry-605 014, Email: gfsudha@rediffmail.com) : Use of laser doppler to classify psoriatic skin lesions. J Optics 2008, 37(2), 63-71.

Psoriasis is a chronic skin disease that can occur in any part of the body. The only diagnostic tool available for psoriasis is skin tissue biopsy. Higher blood flow rate in the infected regions is a clinical symptom of this disease. When light is incident on the skin, the backscattered light carries information of the chromophore it interacts. Hence, the reflected light is processed to calculate the blood flow rate. This paper presents experimental results of blow flow rates measured on psoriatic patients at various stages of the disease. It is also found that skin blood flow can be used to distinguish psoriasis from a form of benign skin cancer.

4 illus, 8 tables, 16 ref