002228   Gunasekaran S;Parthiban T;Rajendran C P; Ganesan S;Manimegalai K (P G and Res Dep of Phys, Pachaiyappa's Coll, Chennai-600 030, Email: sguna_pachai@hotmail.com) : Analysis of synovial fluid based upon native fluorescence spectroscopy. Indian J Phys 2005, 79(2), 207-10.

The study is aimed to address the applications and development of native fluorescence spectrometry as a diagnostic tool and to characterize the synovial fluid of normal and rheumatic disease. To quanitfy the spectral differences and to classify the fluids, an intensity ratio parameter R₁= I₍₃₂₃₎/I₍₃₉₃₎ is introduced and the area under the curve analysis is also dealt with. It is shown that the synovial fluids of rheumatic disease can be classified with greater sensitivity and of normal individuals with higher specificity.

5 illus, 11 ref

002227   Gunasekaran S;Abitha P (PG and Res Dep of Phys, Pachaiyappa's Coll, Chennai) : Fourier transform infrared and FT-Raman spectra and normal coordinate analysis of aminobenzoesaeure. Indian J pure appl Phys 2005, 43(5), 329-34.

The infrared and Raman spectral studies and the normal coordinate analysis of aminobenzoesaeure (AB) have been presented. The Fourier Transform Infrared spectrum has been obtained in the region 4000-400 cm^-1 and the FT-Raman spectrum has been recorded over the range 3500-200 cm^-1. The spectra have been investigated in terms of various fundamental modes of vibration. The observed infrared and Raman spectra exhibit all the salient features reported in literature. Accuracy of the spectral line positions and their bandwidths are found to be satisfactory. The structure of the complex has been established on the basis of C_S symmetry. A normal coordinate analysis has been carried out following Wilson's F.G.matrix method and a systematic set of potential constants has been evaluated. To check whether the chosen set of symmetric coordinates contribute maximum to the potential energy associated with the molecule, the potential energy distribution (FED) has been carried out.

3 illus, 2 tables, 15 ref

002226   Giri V S;Sinha N K (Univ Dep of Phys, Ranchi Univ, Ranchi-834 008) : Phase shifts of HCB's model. Indian J Phys 2005, 79(2), 195-9.

The radial wave equation of a HCB's (hard convex bodies) model coordinate system, has been described and expressed for the pair intermolecular potential specified in terms of the support function h(x) and surface-to-surface coordinate representation for the calculation of the phase shifts. The phase shifts expression for HCB's model reduces to hard sphere (HS) model expression in terms of surface-to-surface coordinate representation for the isotropic-symmetric orientation and for major and minor axis ratio equal to one. The phase shifts for HS model also have been calculated.

3 illus, 4 tables, 7 ref

002225   Gedam R S;Deshpande A V;Deshpande V K (Dep of Appl Phys, Visvesvaraya Natn Inst of Technol, Nagpur-440 011, Email: rsgedam@vnitnagpur.ac.in) : Electrical conductivity of Li_{2O: B2O3 : ZnO glasses.} Indian J Phys 2005, 79(7), 741-3.

The study of electrical conductivity of 27.5 Li₂O : (72.5-x) B₂O₃ : x ZnO glass samples has been carried out. The results have been explained by dividing the temperature range into two regions. In region - I, there is a linear increase in conductivity with temperature for all the samples. The conductivity decreases with addition of ZnO . In region - II, it is observed that for all the samples, the conductivity suddenly increases, exhibits a plateau for certain temperature range and then decreases with further increase in temperature. The increase in conductivity has been attributed to nucleation and the subsequent decrease in conductivity to the crystallization of the glass samples.

4 illus, 17 ref

002224   Dwivedi A (Dep of Phys, Maharana Pratap Engng Coll, Kanpur-209 217, Email: ashu_dwi@yahoo.com) : Hydrodynamic modelling of laser ablated plasmas for pulsed laser deposition. Indian J Phys 2005, 79(2), 183-8.

The expansion dynamics of the plasma generated by laser ablation of materials has been described by a hydrodynamic model. The model described here, considers that the interaction of laser beam with the target material can be divided into three separate regimes : laser-target interaction, laser-plasma interaction and adiabatic expansion of plasma. The third regime is treated separately for vacuum and ambient gas atmospheres. The results on the hydrodynamical modelling of the laser-generated species in vacuum and in background gas atmosphere, are presented. The thickness distribution of the laser deposited layer in vacuum is found to be related to the initial dimensions of the plasma but independent of both the laser fluence and atomic mass of the target. The angular distribution of the deposits have been deduced as a sum of cosⁿθ. The thickness profiles have been found to show suppression due to ambient gas pressure.

6 illus, 38 ref

002223   Dalvi a;Shahi K (Phys Grp, Birla Inst of Technol and Sci, Pilani-333 031, Email: adalvi@bits-pilani.ac.in) : Thermal investigations on mechanically milled and melt-quenched superionic glasses using differential scanning calorimetry. Indian J Phys 2005, 79(7), 727-32.

Differential scanning calorimetry (DSC) has been successfully used to identify important differences between mechanically milled (MM) and melt quenched (MQ) AgI-Ag₂O-M_xO_y (M_xO_y = CrO₃, MoO₃ and V₂O₅) superionic glasses. The MQ as well as MM samples exhibit glass transition (T_g) and amorphous <214> crystalline transition (T_c) temperatures. T_g as well as T_c are found to increase monotonically with heating rate and the crystallization and glass transition kinetics is studied in the MM and MQ samples. The activation energies associated with the crystallization (E_c) and structural relaxation (E_s) at T_g are obtained. The enthalpy and entropy changes (ΔH and ΔS, respectively) at the crystallization temperature are also obtained from the DSC thermograms. An analysis based on these quantities reveals interesting results. Finally, the fundamental differences in the basic characteristics of MM and MQ samples have been pointed out.

8 illus, 1 table, 13 ref

002222   Boor Singh;Sekhon S S (Dep of Appl Phys, Guru Nanak Dev Univ, Amritsar-143 005, Email: sekhon_apd@yahoo.com) : Can lithium ion conducting gels have higher conductivity than the corresponding liquid electrolytes?. Indian J Phys 2005, 79(7), 757-9.

The addition of polymer increases the viscosity of electrolytes, which reduces ionic mobility and as a result, conductivity decreases and generally, σ(gel) <60> (σ (liquid) is observed. However, recent results show that the addition of polymer can also result in an increase in conductivity alongwith an increase in viscosity and σ(gel) <62> σ(liquid) has been observed for lithium ion conducting polymer gel electrolytes. The increase in conductivity has been found to depend upon the dielectric constant of the solvent, concentration of salt and molecular weight of the polymer used.

4 illus, 13 ref

002221   Bhoga S S;Singh K (Dep of Phys, Nagpur Univ, Nagpur-440 033, Email: msrll@hotmail.com) : Performance of electrochemical CO₂ gas sensor with NASICON dispersed in a binary solid electrolyte system. Indian J Phys 2005, 79(7), 725-6.

The potentiometric CO₂ sensor fabricated using NASICON dispersed in 70 Li₂CO₃: 30 BaCO₃ as solid electrolyte and TiO₂-Na₂Ti₆O₁₃ composite, as reference electrode. The sensor found to respond for CO₂, gas concentration and temperature range of 200-2000 ppm and 400-550°C, respectively. The sputtered palladium on the electrolyte side with test gas follows the reaction CO₂+1/2O₂, + 2Li⁺ +2e^- → Li₂CO₃. The cell response was Nernstian showing nearly two electron reactions. The long-term stability of the sensor was good with the response time about 80 seconds.

3 illus, 6 ref

002220   Bhardwaj V;Tiwari V K;Bhatnagar D;Saini J S; Kumar P;Sharma K B (Microwave Laboratory Dep of Phys, Univ of Rajasthan, Jaipur-302 004) : Theoretical analysis of circular disk microstrip antenna with a slot. Indian J Phys 2005, 79(2), 137-42.

The cavity model based modal expansion technique is applied to compute resonant frequency, input impedance, directivity and radiation efficiency of a general circular disk microstrip antenna having a narrow slot (CDMAS). The radiation performance of this circular disk antenna with a narrow slot (β= 5°) is found better in TM₂₁ mode of excitation. The computed results show a fairly good agreement with simulated results obtained with commercial simulation software IE3D. An average deviations within 0.7%; 3.3%, 4.8% and 3.4% respectively, in resonant frequency, directivity, radiation efficiency and input impedance of this structures are recorded which validates this technique of treating proposed geometry.

8 illus, 2 tables, 11 ref

002219   Baskaran R;Selvasekarapandian S (Solid St and Radiat Phys Laboratory Dep of Phys, Bharathiar Univ, Coimbatore-641 046, Email: sekarapandian@yahoo.com) : AC impedance and dielectric spectroscopic studies of proton conducting PVAc-PVdF blended polymer electrolytes. Indian J Phys 2005, 79(7), 777-81.

The blended proton conducting polymer electrolytes comprising of poly(vinyl acetate) (PVAc) and poly(vinylidenefluoride) (PVdF) have been prepared for different ammonium thiocyanate (NH₄SCN) ratio by solution casting technique. The ac conductivity and dielectric spectroscopy studies have been carried out on the blended polymer matrix to reveal the H⁺ conductivity. The high frequency semicircle in the impedance plot reveals the bulk effect of the polymer electrolytes. The proton conductivity has been found to vary from <126> 1.7xl0^-7 Scm^-1 to 4.6x10^-4 Scm^-1 with the increase in salt concentration in the blended polymer matrix at ambient temperature. The ionic transference number of mobile ions has been estimated by Wagner's polarization method and it has been found to be t_ion <126> 0.97 for all the samples. The dielectric spectral studies show the low frequency dispersion, which implies the space charge effects arising from the electrodes.

6 illus, 1 tables, 27 ref

002218   Arif Sanjid M;Nasrin M;Chaudhary K P;Singhal R P (Length and Dimension Stand Div, Natn Phys Laboratory, New Delhi-110 012) : Ramification of uncertainty due to limited resolution of universal measuring machine. Indian J pure appl Phys 2005, 43(5), 319-28.

Universal measuring machine (UMM) is a fundamental displacement-measuring machine equipped with reference standard scale attached to its movable-bed. A microscope is fixed rigidly on the UMM to locate the graduation marks on the reference scale. As the movable-bed moves, the reference scale under the microscope also moves. Therefore, the microscope locates new graduation mark of the reference scale correspondingly. It has been observed that the readings are dependent on the direction (i.e. left to right and right to left) of the movement of the movable-bed. Experiments are performed using a displacement laser interferometer to investigate this problem. It is found that the limited resolution of the microscope, properties of eye and the criterion for the acceptance of reading in the microscope are influencing factors. The effective error components are found experimentally. Based on the error components, the uncertainty due to limited resolution of UMM has been ramified. A novel sensing approach for detecting the graduation marks is described.

6 illus, 6 tables, 10 ref

002217   Amuba Singh C;Babynanda Devi O (Dep of Phys, Manipur Univ, Canchipur, Imphal-795 003, Email: amuchab@rediffmail.com ) : Ladder operator method for the potential V(x) =Ax<. Indian J Phys 2005, 79(2), 131-5.

Adopting a general procedure of constructing ladder operators - energy eigenvalue raising and lowering operators, it is shown that ladder operators which are quadrartic in momentum operator p, that is, which are of the form Q = p² + b(x)p + c(x), can be constructed for and only for the potential of the form V(x) =Ax² + Bx^-2, B<62> 0. By explicitly constructing these operators and the relevant number operator, which is not Q⁺Q, the energy eigenvalues are obtained and the normalized eigenvectors are determined in both the energy representation and the position representation. The operators Q, Q⁺ and H (the Hamiltonian) form a Lie algebra and generate the SU(1,1) Lie group.

9 ref

002216   Ali A;Hyder S;Akhtar Y (Dep of Chem, Jamia Millia Islamia (Central University), New Delhi-110 025, Email: anwar.ch@jmi.ernet.in) : Viscometric studies of α-amino acid in aqueous NaCl and MgCl₂ at 303 K. Indian J Phys 2005, 79(2), 157-60.

Densities, and viscosities of glycine in aqueous solutions of 0.02, 0.06 and 0.10 M NaCl and MgCl₂ as a function of glycine concentration are measured at 303 K. The viscosity data have been analyzed by means of Jones-Dole equation to calculate A and B coefficients. The activation parameters of viscous flow, namely, free energies of activation of viscous flow, per mole of solvent and solute were obtained by the application of transition state theory. The results show the presence of weak solute-solute and strong solute-solvent interactions and also that both solutes act as structure-makers in aqueous glycine.

3 tables, 13 ref

002215   Agrawal R C;Pandey G P;Singh D;Verma M L (Solid St Ionics Res Laboratory Sch of Stud in Phys, Pt. Ravishankar Univ, Raipur-492 010, Email: ircrsu@sanchernet.in) : A novel liquid-solid lead-acid secondary battery: study of charge-discharge behavior. Indian J Phys 2005, 79(7), 711-14.

Lead-acid secondary batteries are used traditionally worldwide as power sources in number of electrical utilities. These batteries are bulky in size and less rugged, hence, pose several handling problems. Recently, a novel prototype lead-acid battery based on liquid-solid composite structure, has been designed which is a miniature version and can withstand several charge-discharge cyclability. Fabrication and discharge characteristic studies on these secondary batteries have been reported. The results are based on some preliminary measurements. An open circuit voltage (OCV) <126> 1.9V has been obtained which is very close to the OCV value (<126> 2V) of the conventional lead-acid battery. The cell performance has been studied under different load conditions and for seven charge-discharge cycles.

3 illus, 1 table, 11 ref

002214   Agrawal R C;Bhatt A;Chandra A;Diwan P;Verma M L (Solid St Ionics Res Laboratory Sch of Stud in Phys, Pt Ravishankar Shukla Univ, Raipur-492 010, Email: ircrsu@sancharnet.in) : Transport property studies on a new silver ternary glassy electrolyte system: x[0.75 AgI:0.25 AgCl] : (1-x) [Ag₂O:V₂O₅]. Indian J Phys 2005, 79(7), 737-40.

Investigations on ion transport behavior in the newly synthesized silver ternary glassy electrolyte systems: x [0.75AgI : 0.25AgCl] : (l-x)[Ag₂O:V₂O₅], where 0.1<60> x <60>1 in molar weight fraction, are reported. These systems were prepared by roller quenching technique. An alternate host: 'a quenched [0.75AgI:0.25AgCl] mixed system/solid solution', was used in place of the traditional host AgI. The alternate host has been reported to yield number of fast Ag⁺ ion conducting glassy/ composite systems with superior electrolyte properties as compared to those prepared identically with AgI. The composition dependent conductivity studies at room temperature revealed that the composition: 0.8[0.75AgI:0.25AgCl]:0.2[Ag₂O:V₂O₅] has the highest conductivity (σ <126> 9 x 10^-3 Scm^-1 at 300K). This has been referred to as Optimum Conducting Composition (OCC). An enhancement of more than an order of magnitude in the conductivity has been achieved in OCC from that of the pure host with σ <126> 3.1 x 10^-4 Scm^-1 at 300K. The phase identification studies on OCC using XRD and DTA techniques confirmed the formation of the glassy phase. To identify the reason for conductivity increase in OCC, direct determination of ionic mobility (μ) has been carried out by Transient Ionic Current (TIC) technique. Subsequently, the mobile ion concentration (n) has been evaluated with the help of conductivity and mobility data. The temperature-dependent-conductivity measurements have been carried out on OCC to compute the activation energy (Ea) from 'log σ -1/T' Arrhenius plot.

4 illus, 1 table, 24 ref

001123   Yamada Y (Natn Metrology Inst of Japan, Natn Inst of Advd Industrial Sci and Technol, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan, Email: y.yamada@aist.go.jp) : Advances in high-temperature standards above 1000°C. MAPAN 2005, 20(2), 183-91.

Temperature fixed points are extensively used within the International Temperature Scale at lower temperatures for scale realization, maintenance, and dissemination, as well as for its definition. These are now they are becoming available above 1100°C. High-temperature fixed points based on metal-carbon and metal carbide-carbon eutectic alloys can potentially extend the fixed-point temperature range to above 3000°C, and have become a topic of extensive research worldwide. Five years after, their first report, these are entering the phase of practical use. The principle, performance and research efforts at various National Metrology Institutes, and prospective applications are reviewed.

5 illus, 40 ref

001122   Yacoot A;Downes M;Flugge J (Natn Phys Lab, , Queens Road, Teddington, Middlesex TW11 0LW, UK, Email: jens.fluegge@ptb.de) : Interferometric length measurement. MAPAN 2005, 20(2), 99-114.

Laser interferometers are flexible and powerful instruments for the measurement of displacement. Owing to the high cost of frequency stabilised lasers and need to determine the refractive index of air when making measurements, interferometers are mainly used for high precision two dimensional measurements in semiconductor industry and for primary measurements with a direct link to the definition of the metre. However laser interferometers are also used for measurement of large distances where encoders are often too unmanageable and for special applications such as laser trackers that measure in three dimensions. This contribution gives an overview of various laser interferometers and discusses the main sources of uncertainty. Examples for the use of interferometers are given and the principle and use of X-ray interferometers is also described.

11 illus, 66 ref

001121   Wilkening G;Bosse H (Physikalisch-Technische Bundesanstalt, , Bundesallee 100, 38116 Braunschweig, Germany, Email: harald.bosse@ptb.de) : Nano- and micrometrology - state-of-the art and future challenges. MAPAN 2005, 20(2), 125-51.

Nanometrology is the science and practice of measurement of functionally important, mostly dimensional parameters on components with at least one critical dimension which is smaller than 100 nm. Micrometrology can be described in a similar way, however, the critical dimensions of the functional components in this case are usually defined to be much less than 1 mm. In parallel with the shrinking dimensions of the components and structures produced in nano- and microtechnology, the required measurement uncertainties for dimensional metrology in these important technology fields are decreasing too. New measurement methods as well as improvement of already existing methods in different respects like e.g. signal modelling, uncertainty calculation, production of better standards, etc. are necessary to cope with the increasing manufacturing requirements of nano- and microtechnological products and components. This contribution will provide an overview on developments in the field of nano- and micrometrology from the point of view of a metrology institute.

33 illus, 3 tables, 48 ref

001120   Waldele F S;Chwenke H;Keck C (Physikalisch Technische Bundesanstalt, , Bundesallee 100, 38116 Braunschweig, Germany, Email: franz.waeldele@ptb.de) : Coordinate metrology evaluation of task specific uncretainties by simulation. MAPAN 2005, 20(2), 153-64.

Co-ordinate measuring machines (CMM) are versatile measuring instruments for the geometrical inspection of complex industrial parts. The uncertainty of measurements on CMMs is extremely difficult to determine, as the influences from the CMM, the measured part, and the environment, affect each measurement in a different way. The "Virtual Co-ordinate Measurement Machine" (VCMM) permits the automatic determination of measurement uncertainties for co-ordinate measurements using Monte Carlo simulation. The VCMM forms an integral part of the CMM evaluation software and automatically adapts to the measurement task. This makes the VCMM especially suited for the complex and frequently changing CMM measurement tasks, such as the calibration of master parts in industry. This article describes the VCMM principle of operation. It outlines the models of the influences considered by the VCMM, focusing on the geometric errors caused mechanical imperfections and thermal influences. Measurements on a reference artefact demonstrate the capability of the VCMM to correctly determine the uncertainty of measurements. Methods for re-verification and monitoring of the system based on calibrated artefacts are introduced to ensure the validity of the uncertainty values over time.

9 illus, 17 ref

001119   Varshni Y P (Dep of Phys, Univ of Ottawa, Canada KIN 6N5, Email: ypvsj@uottawa.ca) : Effect of the parabolic confinement potential on the binding energy of a donor in a double-step barrier quantum dot. Indian J Phys 2005, 79(3), 235-7.

The effect of the parabolic confinement potential due to electrons on the binding energy of a donor impurity centered in a double step potential barrier quantum dot has been investigated within the effective mass approximation, as a fuction of the dot radius(R). Calculations as performed for several states using a numerical method both with and without the parabolic confinement potential. the results show that as the dot radius increases, the effect of the parabolic potential depends very much on the state and quite complex.

4 illus, 18 ref

001118   Valsakumar M C (Mater Sci Div, Indira Gandhi Cent for Atom Res, Kalpakkam-603 102, Email: valsa@igcar.ernet.in) : Stochasticity, decohereence and an arrow of time from the discretization of time?. Pramana J Phys 2005, 64(4), 593-606.

Certain intriguing consequences of the discreteness of time on the time evolution of dynamical systems are discussed. In the discrete time classical mechanics proposed here, there is an arrow of time that follows from the fact that the replacement of the time derivative by the backward difference operator alone can preserve the non-negativity of the phase space density. It is seen that, even for free particles, all the degrees of freedom are correlated in principle. The forward evolution of functions of phase space variables by a finite number of time steps, in this discrete-time mechanics, depends on the entire continuous-time history in the interval [0, ∞]. In this sense, discrete time evolution is non-local in time from a continuous-time point of view. A corresponding quantum mechanical treatment is possible via the density matrix approach. The interference between non-degenerate quantum mechanical states decays exponentially. This decoherence is present, in principle, for all systems; however, it is of practical importance only in macroscopic systems, or in processes involving large energy changes.

21 ref

001117   Singh V;Tiwari M;Dhoble S J (department of Post Grad Stud & Res In Phys, Bhoj Coll, Kotra, Bhopal-462 003, Email: vijavjiin@hotmail.com) : Eu<. Indian J Phys 2005, 79(3), 313-15.

CaS phosphors activated with Eu³⁺ and Sm³⁺ ions, were prepared by using solid-state diffusion method. Emission and excitation spectra were recorded at room temperature on CaS:Eu and CaS:Eu,Sm phosphors with the aim of their photoluminescence characterization as well as the enery transfer process. CaS phosphor shows the strong emission of Sm³⁺ ions in red region of spectrum due to energy transfer from Eu³⁺ to Sm³⁺ ions. Thermoluminescence study was also carried out of CaS:Eu and CaS:Eu,Sm phosphors.

2 illus, 11 ref

001116   Singh B P;Mahor H S;Tripti S (Dep of Phys, Inst of Basic Sci, Khandari, Agra-282 002, Email: drbps@sancharnet.in) : Relationships between electronic dielectric constants and interatomic separations in A<. Indian J Phys 2005, 79(3), 273-7.

3 illus, 3 tables, 14 ref

001115   Sen A;Dodla R;Johnston G L (Inst for Plasma Res, , Bhat, Gandhinagar-382 428, Email: abhijit@ipr.res.in) : Collective dynamics of delay-coupled limit cycle oscillators. Pramana J Phys 2005, 64(4), 465-82.

Coupled limit cycle oscillators with instantaneous mutual coupling offer a useful but idealized mathematical paradigm for the study of collective behavior in a wide variety of biological, physical and chemical systems. In most real-life systems however the interaction is not instantaneous but is delayed due to finite propagation times of signals, reaction times of chemicals, individual neuron firing periods in neural networks etc. Present brief overview of the effect of time-delayed coupling on the collective dynamics of such coupled systems. Simple model equations describing two oscillators with a discrete time-delayed coupling as well as those describing linear arrays of a large number of oscillators with time-delayed global or local couplings are studied. Analytic and numerical results pertaining to time delay induced changes in the onset and stability of amplitude death and phase-locked states are discussed. A number of recent experimental and theoretical studies reveal interesting new directions of research in this field and suggest exciting future areas of exploration and applications.

5 illus, 52 ref

001114   Sarah R P;Kumar G S (CVR Coll of Engng, , Vastunagar, Mangalpalli (V), R R district-501 510, Email: pasala_sarah@yahoo.com) : Electrical properties of cationic-substituted SrBi₂Ta₂O₉. Indian J Phys 2005, 79(3), 267-72.

Modifications of SrBi₂Ta₂)₉ are investigated by substituting Ca for Sr and doping La for Bi. The dielectric and electrical properties are studied together with the microstructures. Polycrystalline samples Ca_0.1Sr_0.9Bi₂Ta₂O₉ (CSBT) and Ca_0.1Sr_0.9La_0.025Bi_1.975Ta₂O₉ (CSLBT) are prepared by solid-state double sintering route. X-ray diffraction (XRD) confirms single-phase formation and XRD reflections shift to lower and higher angles with Ca²⁺ and La³⁺ substitution, respectively. There is a decrease in the lattice parameters because of this cationic substitution. The particle size distribution is studied using scanning electron microscope (SEM). The dielectric constant and loss are measurred as a function of temperature at different frequencies. The ferroelectric Curie temperature decreased from 373°C (CSBT) t 340°C (CSLBT) at 50KHz. The dc conductivity as a function of temperature, is measured. There is a reduction in conduction with La-doping in CSBT. Activation energy is calculated from the slopes of dc conductivity Arrhenius plots.

9 illus, 3 tables, 34 ref

001113   Saprtsky V I;Khlevnoy B B;Ogarev S A;Samoylov M L;Shapoval V I;Sakharov M K (All Russian Res Inst of Optical and Phys Measurements (VNIIOFI), , Section M-4, Ozernaya 46, 119361, Russia, Email: ogarev-m4@vniiofi.ru) : New high temperature variable temperature and fixed point blackbodies for precision measurements in radiation thermometry and radiometry. MAPAN 2005, 20(2), 193-204.

The review of the latest generation of precision high-temperature blackbodies, developed at VNIIOFI during last 2 years - both Variable-Temperature Black Body (VTBB) and Fixed-Point Black Body (FPBB) types, is presented. Direct prototypes of new VTBB, high temperature pyrolitic graphite blackbodies BB3200 and BB3500 had been developed within the last decade of years and used in several world-leading metrology centers for realization and dissemination of radiometric and radiation temperature scales, including operation as furnaces for heating the cells containing fixed-point blackbodies on the base of metal-carbon eutectics with the temperatures up to 3500K (covering TiC-C at 3033 K, ZrC-C at 3155 K and HfC-C at 3453K). The FPBB sources - Re-C, TiC-C, ZrC-C and HJC-C cells have been developed and investigated. Two types of crucibles were used: with 4 and 10 mm radiating cavities. Transition temperatures were measured according to ITS with a radiance-mode pyrometer. The freezing temperatures were 2747.9±1.3 K, 3033.6±1.6 K, 3155.0±1.8 K and 3458.5±2.5 K (k=2)for Re-C, TiC-C, ZrC-C and HfC-C respectively.

7 illus, 6 table, 15 ref

001112   Sanjeev Kumar;Shyam Kumar;Chakarvarti S K (Dep of Phys, Ambala Coll of Engng & Appl Res, Devsthali (Near Mithapur), Ambala-133 101) : Galvanic synthesis of copper microstructures on large areas of polymeric ion track membranes. Indian J Phys 2005, 79(3), 245-9.

60 μm thick polycarbonate foils were irradiated to ²⁰⁸Pb ions (energy-11.6 MeV/n, flux~10⁷ ions/em²). Irradiated polycarbonate foils were chemically etched in 6n NaOH solution at 50(C for 25 minutes. aligned copper microstructure bunches have been prepared by electrodeposition in porous polycarbonate templates from acidic copper sulphate solution at 25°C and 45°C respectively. Copper microstructures with uniform diameter ~ 1.5μm and length ~ 60μm were obtained, which corresponds to the pore sizes of the templates used. The XRD analysis of the samples has revealed that the copper microstructures are polycrystalline in nature.

4 illus, 17 ref

001111   Rudtsch S;Tegeler E;Fischer J (Physikalisch Technische Bundesanstalt, , Abbestr. 2-12, 10587 Berlin, Germany, Email: joachim.fischer@ptb.de) : Calibration of contact thermometers above the triple point of water at PTB. MAPAN 2005, 20(2), 165-9.

In its function as the National Metrology Institute of Germany PTB is responsible for the realization and dissemination of the International Temperature Scale of 1990 (ITS-90). This includes the participation in international comparisons and the surveillance of the German calibration service. According to the needs of the customers different methods and levels of accuracy are offered. Several different types of fixed-point cells, furnaces and maintenance baths are operated in order to fulfill the requirements. The highest level of accuracy is realized by calibration of fixed-point cells standard platinum resistance thermometers (SPRTs) by means of state of the art ITS-90 fixed-point cells and the corresponding measurement equipment. The calibration of thermocouples is carried out by a different set of ITS-90 fixed-point cells supplemented by the palladium fixed-point and special equipment for homogeneity investigations. For the calibration of thermistors, industrial platinum resistance and liquid-in-glass thermometers the comparison method in stirred liquid baths of highest stability and temperature homogeneity are used. The paper presents the methods, equipment and uncertainties associated with the different calibration methods. In addition to that, there are several ongoing projects in order to improve the ITS-90 fixed points and the calibration facilities for ac- and dc-resistance ratio bridges.

1 illus, 5 tables, 6 ref

001110   Roychowdhury A P (Aerodynamics R & D Div, Vikram Sarabhai Space Cent, Triuvananthapuram-695 022) : Absolute and convective instability study of weakly compressible mixing layers. Indian J Radio Space Phys 2005, 34(2), 106-13.

This is an analysis of stability study of weakly compressible mixing layers under non-homentropic flow conditions. The condition of non-zero group velocity required for convective instability analysis was seen to give new findings as stated below. Also, the.dispersion relationships are functions of the cross-stream derivatives, Mach number and chemical reaction parameters. Three modes of oscillations for developing mixing layer were chosen based on previous findings of the author and later in this work their possible validity were confirmed as follows. Jet mode (Mode 1), mixed mode (Mode II) and fully developed mixing layer mode (Mode III) oscillations for developing mixing layers are considered in this study. Using impulse response technique it is seen that for symmetric temperature profile, Mode I is absolutely unstable, Mode II is both convectively and absolutely unstable, partially each, and Mode III is dominantly convectively unstable with pockets of absolute instability. For the asymmetric temperature profile of T= 1+ λ tanh (y), Mode I is weakly convectively unstable, Mode II is weakly absolutely unstable and Mode III is convectively unstable for major regions of the flow.

6 illus, 14 ref

001109   Roy S K;Jha L (Univ Dep of Phys, L N Mithila Univ, Darbhanga-846 004) : Effects of tuning stub on microstrip patch antenna. Indian J Radio Space Phys 2005, 34(2), 139-41.

Use of tuning stubs to trim the phase of a microstrip feed line or to tune the resonant frequency of a microstrip patch antenna is discussed in the paper. The variation of resonant frequency with stub-length of microstrip patch antenna is also discussed. The experimental results regarding phase shift and resonant frequency with stub-length are in good agreement with the theoretical results.

3 illus, 9 ref

001108   Rastogi R G (Dep of Phys, Guj Univ, Ahmedabad-380 009) : First observations of geomagnetic field variations within equatorial electrojet belt in Sri Lanka. Indian J Radio Space Phys 2004, 33(2), 83-7.

The daily variations of the geomagnetic horizontal (H), eastward (Y) and vertical (Z) fields at any equatorial electrojet station south of India have been described, for the first time, using the data from Peredinia, Sri Lanka (geogr. lat. 7.3°N, long. 80.6°E, dip lat. 1.3°S). An abnormal positive peak in the daily variation of the Z field at Peredinia (PRD) in the forenoon hours, stronger in magnitude to corresponding abnormality in Z at Trivandrum (TRD), India has been detected. There is a remarkable correspondence between ΔZ at Trivandrum and Peredinia on day-to day-basis, the variations being stronger at Peredinia than at Trivandrum. During a magnetic storm a sharp decrease of ΔZ is observed few hours before the maximum decrease of H at both PRD and TRD. These observations show, for the first time, that the induction anomalies in the equatorial electrojet region in Indo-Sri Lanka longitudes extend well beyond the southern tip of Indian Peninsula. The phenomenon of subsurface induction in Indian longitudes needs to be seriously reconsidered.

6 illus, 14 ref

001107   Ram Prakash;Gupta D D;Singh A P (Dep of Phys, Bipin Bihari P G Coll, Jhanshi-284 001) : A theoretical explanation of intensity of low latitude ELF emissions and identification of their generation mechanism. Indian J Radio Space Phys 2005, 34(2), 91-7.

The intensities of low latitude ELF hiss emissions are calculated for known plasma parameters by considering incoherent Cerenkov emission mechanism and electron cyclotron resonance instability mechanism. The equatorial intensities calculated in incoherent Cerenkov emission mechanism at L = 1.30-5.50, being several orders of magnitude lower than the observed intensities, rule out the possibility of generation of low latitude ELF hiss emissions in this mechanism. Unlike this, the intensities calculated by electron cyclotron resonance instability mechanism at the equatorial locations above L = 4 are found to be consistent with the intensities observed in the low latitude ground stations. Therefore, it is opined that these emissions originate in the electron cyclotron resonance instability mechanism above L = 4 in the equatorial plane. However, it has been shown that the ELF hiss band below 1 kHz propagates from the generation region in the vicinity of the plasmapause to low latitudes after several successive magnetospheric reflections there, confirming the suggestion of Hayakawa et al.

3 illus, 2 tables, 32 ref

001106   Rajnikant;Dinesh;Mousmi;Aziz N;Varghese B (Condensed Matter Phys Grp Post Grad Dep of Phys, Univ of Jammu, Jammu Tawi-180 006, Email: rkantverma@rediffmail.com) : Structure analysis of 3β-acetoxy-12-keto-(25R)-5β-spiros tanyl acetate. Indian J Phys 2005, 79(3), 285-7.

The crystal structure of 3β-acetoxy-12-keto-(25R)-5β-spirostanyl acetate has been determined by X-ray diffraction methods. The title compound (C₂₉H₄₄O₅) crystallizes in monoclinc space group P2₁ with cell parameters, a=10.547(4), b=7.124(8), c=18.110(10) Å, β = 98.23(4)° and Z = 2. The reliability index of the structure is 0.068 for 1645 observed reflections. Four six-membered rings A, B, C and F exist in chair conformation. the five-membered ring D occupies a distorted half-chair conformation while the ring E adopts a half chair conformation. The crystal structure is stabilized by few C-H... O intra- and intermolecular interactions.

3 illus, 4 tables, 17 ref

001105   Prasad A;Iasemidis L D;Sabesan S;Tsakalis K (Dep of Phys and Astrophys, Univ of Delhi, Delhi-110 007) : Dynamical hysteresis and spatial synchronization in coupled non-identical chaotic oscillators. Pramana J Phys 2005, 64(4), 513-23.

Authors identify a novel phenomenon in distinct (namely non-identical) coupled chaotic systems, which authors term dynamical hysteresis. This behavior, which appears to be universal, is defined in terms of the system dynamics (quantified for example through the Lyapunov exponents), and arises from the presence of at least two coexisting stable attractors over a finite range of coupling, with a change of stability outside this range. Further characterization via mutual synchronization indices reveals that one attractor corresponds to spatially synchronized oscillators, while the other corresponds to desynchronized oscillators. Dynamical hysteresis may thus help to understand critical aspects of the dynamical behavior of complex biological systems, e.g. seizures in the epileptic brain can be viewed as transitions between different dynamical phases caused by time dependence in the brain's internal coupling.

6 illus, 12 ref

001104   Pisarchik A N;Reategui R J (Centro de Investigaciones en Optica Loma del Bosque 115 Lomas del Camp, , Leon 37150, Guanajuato, Mexico, Email: apisarch@cio.mx) : Intermittent lag synchronization in a driven system of coupled oscillators. Pramana J Phys 2005, 64(4), 503-11.

Authors study intermittent lag synchronization in a system of two identical mutually coupled Duffing oscillators with parametric modultion in one of them. This phenomenon in a periodically forced system can be seen as intermittent jump from phase to lag synchronization, during which the chaotic trajectory visits a periodic orbit closely. Author demonstrate different types of intermittent lag synchronizations, that occur in the vicinity of saddle-node bifurcations where the system changes its dynamical state, and characterize the simplest case of period-one intermittent lag synchronization.

5 illus, 29 ref

001103   Nomita Devi K;Basantakumar Sharma H; Nandakumar Sarma H (Dep of Phys, Manipur Univ, Canchipur, Imphal-795 003, Email: hnksarma@rediffmail.com) : Dielectric properties and dc conductivity of lampblack. Indian J Phys 2005, 79(3), 309-11.

The dielectric properties and dc conductivity of lampblack samples have been investigated. The dielectric constant (F128><101> and loss tangent (tanδ) show strong frequency dependence. The dielectric constant also shows an anomaly peak at about 330K, while no such peak was observed in tanδ. Two distinct regions can be divided in the dc conductivity (σ_dc) and temperature plot, with a discontinuity at 330K. Both the dielectric and dc conductivity studies predict a possible phase transition from polar to non-polar at 330K. The results are analyzed and discussed in the light of results reported in the literature.

4 illus, 5 ref

001102   Mallick B;Rautray T R;Nayak P K;Vijayan V; Singh P;Behera R C;Patel T;Choudhury R K (Inst of Phys, , Sachivalaya Marg, Bhubaneswar-751 005, Email: bmallick@iopb.res.in) : Characterisation of hot material erupted from mahanadi riverbank using EDXRF and XRD techniques. Indian J Phys 2005, 79(3), 293-6.

A detailed mineralogical study was carried out on iron-rich hot material oozed out from Mahanadi riverbank, Cuttack in Orissa. Both qualitative and quantitative estimation of the multi-elements of this complex material was carried out by Energy Dispersive X-ray Fluorescence (EDXRF) technique. among the analysed elements, iron is found to be in highest concentration i.e. 18.8%, whereas K, Ca, Ti and Mn are present as minor constituent, and V, Cr, Co, Cu, Zn, Se, Rb, Sr and Pb are present in trace quantities. different crystallographic phases like maghemite (γ-Fe₂O₃, hematite (Fe₂O₃, chromite (FeCr₂O₄, cuprospinel (CuFe₂O), cuprite (Cu₂O), zhanghengite (CuZn), ramsdellite (MnO₂), mullite (Al₆Si,v>4 O₃), anatase (TiO₂), marokite (CaMn₂O₄), zincochromite (ZnCr₂O₄) and baddelete (ZrO₂ have been observed prominently. Some low intense lines of potassium chlorite (KCIO₂) and karelianite (V₂O₃) are also identified by the X-ray powder diffraction (XRD) technique.

2 illus, 2 tables, 13 ref

001101   Mahadevan C (Phys Res Cent, S T Hindu Colleg, Nagercoil-629 002, Email: mahad@sancharnet.in) : Effect of organic impurities on the cucleation parameters of KDP single crystals. Indian J Phys 2005, 79(3), 305-7.

Induction periods have been measured for various supersaturated aqueous solutions of potassium dihydrogen orthophosphate crystal (KDP) added separately with glycine and thiourea by the direct vision method. Various critical nucleation parameters have been calculated based on the classical theory for homogeneous crystal nucleation. the critical nucleation parameters increase with the increase in concentration of impurity in the KDP solution.

1 table, 10 ref

001100   Laik A;Kale G B (Mater Sci Div, Bhabha Atom Res Cent, Mumbai-400 085, Email: gbkale@apsara.barc.ernet.in) : On relating thermodynamic diffusion coefficients with phenomenological coefficients in binary systems. Trans Indian Inst Metals 2005, 58(1), 133-5.

A relation between the thermodynamic diffusion coefficients (D_i(μ)) and the phenomenological transport coefficients (L_ij) has been derived for binary systems. The relation is similar to the relation between tracer diffusion coefficient, D_i and the phenomenological coefficients, L_ij. This shows the equivalence between thermodynamic intrinsic diffusion coefficient and tracer diffusion coefficient.

4 ref

001099   Lai Y C;Motter A;Nishikawa T;Park K;Zhao L (Dep of Electl Engng, Arizona St Univ, Tempe, Arizona-85287, USA, Email: yclai@chaosl.la.asu.edu) : Complex networks : dynamics and security. Pramana J Phys 2005, 64(4), 483-502.

The paper presents a perspective in the study of complex networks by focusing on how dynamics may affect network security under attacks. In particular, authors has reviewed two related problems: attack-induced cascading breakdown and range-based attacks on links. A cascade in a network means the failure of a substantial fraction of the entire network in a cascading manner, which can be induced by the failure of or on only a few nodes. These have been reported for the internet and for the power grid (e.g., the August 10, 1996 failure of the western United States power grid). Authors study a mechanism for cascades in complex networks by constructing a model incorporating the flows of information and physical quantities in the network. Using this model authors has also shown that the cascading phenomenon can be understood as a phase transition in terms of the key parameter characterizing the node capacity. For a parameter value below the phase-transition point, cascading failures can cause the network to disintegrate almost entirely. Authors has shown how to obtain a theoretical estimate for the phase-transition point. The second problem is motivated by the fact that most existing works on the security of complex networks consider attacks on nodes rather than on links. Authors address attacks on links. The investigation leads to the finding that many scale-free networks are more sensitive to attacks on short-range than on long-range links. Considering that the small-world phenomenon in complex networks has been identified as being due to the presence of long-range links, i.e., links connecting nodes that would otherwise be separated by a long node-to-node distance, our result, besides its importance concerning network efficiency and security, has the striking implication that the small-world property of scale-free network is mainly due to short-range links.

12 illus, 47 ref

001098   Kanamadi C M;Kharabe R G;Pujar R B;Chougule B K (Ferrite Mater Res Lab Dep of Phys, Shivaji Univ, Kolhapur-416 004, Email: bkchougule@yahoo.com) : Microstructure and initial permeability of Cd-substituted Li-Ni ferrites. Indian J Phys 2005, 79(3), 257-60.

The microstructure and initial permeability of Cd-substituted Li-Ni ferrites having the general formula Li_0.5Ni_0.75-x/2 Cd_x/2Fe₂O₄ (where x=0, 0.1, 0.3, 0.5, 0.7 and 0.9), have been reported. The ferrite samples were prepared by standard double sintering ceramic technique and characterized by X-ray diffraction. The lattice parameter (a) increases with increase in CD content. The SEM studies show that the average grain diameter increases as the content of cadmium increases. the initial permeability (μ_i) increases as Cd content increase. It is observed that μ_i increases gradually with temperature and then it drops near curie temperature. The Curie temperature of the samples decreases with increase in content of cadimum due to reduction in A-B interaction. The variation of initial permeability with frequency shows that <109>_i remains invariant with frequency for all samples except with x=0.9 in which it starts increasing beyond 1 MHz of applied frequency.

7 illus, 12 ref

001097   James M E;Rastogi R G;Winch D E (Dep of Phys, Guj Univ, Ahmedabad-380 009) : Magnetic disturbance effect on geomagnetic field at low latitudes. Indian J Radio Space Phys 2004, 33(2), 88-94.

Relationship between daily means of H and Y fields with D_st index for stations with in a low latitude belt around the world has been investigated. The H field decreases linearly with decreasing d_st, the slope being less than unity at all stations. But Y field variation with D_st, exhibited a longitudinal dependence. The ring current follows the dipole coordinates and not the dip coordinates and hence changes in Y field are related to both dipole declination (ψ) and dip declination (D) such that ΔY/ΔH = sin(ψ-D), both in sign and magnitude. Good correspondence is seen between ΔY/ΔH and sin(ψ- D) for all stations in the equatorial belt.

6 illus, 1 table, 13 ref

001096   Goyal S L;Mohindra R K (Dep of Phys, Kurukshetra Univ, Kurukshetra-132 119, Email: goyalsnesh1@rediffmail.com) : Excitation functions of neutron induced reactions on <. Indian J Phys 2005, 79(3), 317-21.

Excitation functions of ⁵²Cr, ⁵⁴Cr and ⁵⁶Fe for (n, p), (n, α), (n, d), (n, t) and (n, ^3He) reactions induced by 1-20 MeV neutrons have been computed. The computations are based on the evaporation model considering the pre-equilibrium emission mechanism under some approximations. The computer codes SC2N3N, NX-1 and NX-2 have been used for these computations. The excitation functions were also computed using the computer code ALICE-91. The excitation functions of different isotopes have been shown in figures alongwith the available recent experimental data and the results are in fairly good agreement for the reactions where experimental values are available.

12 illus, 1 table, 17 ref

001095   Ghosh D;Deb A;Bandyopadhyay P;Ghosh A;Mondal M;Sengupta R (Nuclear & Particle Phys Res Cent, Jadavpur Univ, Kolkata-700 032, Email: dg@juphys.ernet.in) : Validity of negative binomial distribution among the target fragments emitted in high energy h-A interactions. Indian J Phys 2005, 79(3), 323-5.

Validity of negative binomial distribution is tested for the medium and low energy target fragments emitted in 350 GeV/c π^- - AgBr interactions. It is observed that in both the hemispheres, forward and backward and also in whole phase space, the validity is well satified. This signifies that the mechanism of production of the target fragments is internuclear cascading. Analysis also enlighten the old concept of correlated clusters in terms of cascade phenomena.

2 illus, 2 tables, 5 ref

001094   Gartia R K;Arunkumar Sharma B;Binoykumar Singh;Nabadwip Singh S;Basanta Singh T (Luminescence Dating Lab, Manipur Univ, Canchipur, Imphal-795 003, Manipur) : Spectroscopy of traps in Al₂O₃/Al₂O₃-based phosphors as determined by CGCD of glow curves. Indian J Phys 2005, 79(3), 251-6.

Trap spectroscopy of Al₂O₃ and Al₂O₃ (TLD-500) has been determined by resorting to Computerized Glow Curve Deconvolution (CGCD) in the frame work of Kinetic formalism. Unlike generally followed practices, in this case, the criteria for acceptance of a fit is determined by the X²- test. As a crosscheck, the Figure of Merit (FOM) is also evaluated. The results of CGCD of glow curves of β - irradiated alumina as well as that some recently published results reveal interesting findings. these are; all the glow curves can be fitted with a combination of a set of glow peaks with eiscrete energy levels. Further, unlike some earlier results, the higher temperature glow peaks as expected, have higher activation energy. As many as nine traps could be located for the glow peaks in the range 330K - 710K. the traps are pretty close to each other giving an apparent picture of distributed traps. Finally, deconvolution of as many as nine glow curves, shows that the frequency factor is more or less constant with a value (3±2) x 10¹¹sec^-1, while U_m = E/kT_m = 30±1. The results are critically discussed to clarify some misconception that has arisen in the literature because of misjudgment to locate the global minima of the fitting.

2 illus, 2 tables, 20 ref

001093   Friederici S;Tegeler E (Physikalisch-Technische Bundesanstalt, , Abbestr 2-12, 10587 Berlin, Germany, Email: erich.tegeler@ptb.de) : Traceability and metrological infrastructure for industrial temperature measurements in Germany. MAPAN 2005, 20(2), 171-81.

Temperature measurements traceable to the national standards are necessary for applications in fields such as chemicals production, metallurgy, food storage, and heating systems. In, Germany many of the calibrations necessary for the traceability chain are performed by accredited calibration laboratories of the German Calibration Service (DKD). About 50 laboratories are accredited for the calibration of instruments such as resistance thermometers, thermocouples, liquid-in-glass thermometers and radiation thermometers. An increasing number of laboratories are accredited for the calibration of industrial equipment such as temperature block calibrators and climatic chambers. DKD calibration guidelines are essential for unified procedures applied by users of such instruments and the calibration laboratories. Besides the assessment of the quality manual and the laboratory equipment, also interlaboratory comparisons are an important measure to build confidence in the calibrations. These are performed on the one hand on the occasion of the assessments and surveillance visits, and on the other hand in well organised loops in which all accredited laboratories have to participate. Results of an interlaboratory comparison with temperature block calibrators are given.

3 illus, 3 tables, 7 ref

001092   Farag A A M;Abdel Rahman S;Ibrahim a M (Dep of Phys Fac of Educ, ain Shams Univ Roxy, Heliopolis, Cairo, Egypt-11757, Email: alaafaragg@hotmail.com) : Influence of temperature and frequency on the electrical parameters of a polycrystalline silver thallium selenide AgTISe. Indian J Phys 2005, 79(3), 261-6.

The a.c. electrical properties of bulk AgTISe have been studied in the frequency range 10²-10⁵ Hz and in the temperature range 300 - 495 K. Measurements revealed that the a.c. conductivity σ(ω) varied as ω^s, where the index s was variable and always less than unity. The temperature dependence of both a.c. conductivity and the index s is reasonable well interpreted the the correlated barrier hopping (CBH) model. Measurements of capacitance and loss tangent showed a well defined decrease with increasing frequency and an increase with increasing temperature. an interpretation is presented, based on existing theory, for the case of a thermally activated process when using ohmic contacts.

9 illus, 32 ref

001091   De Chiffre L;Kunzmann H;Peggs G N;Lucca D A (Dept of Manufacturing Engng & Mgmt, Tech Univ of Denm, Bldg. 425, 2800 KGS LYNGBY, Denmark, Email: h.kunzmann@web.de) : Product surfaces in precision engineering, microengineering and nanotechnology. MAPAN 2005, 20(2), 115-23.

The paper is an excerpt from a recently published CIRP Key-Note paper on surfaces in precision engineering, microengineering and nanotechnology. It is focussed on the relevance of surface metrology at the micrometric and nanometric length scales. The applied measurement technologies are strongly dependent from the functional requirements on those surfaces. Examples of surfaces obtained with precision engineering, microengineering and nanotechnology are mentioned, encompassing surfaces in computers, MEMS, biomedical systems, light and X-ray optics, as well as in chemical systems. Surface properties at micro and nanoscale are considered, including geometry as well as physical and chemical properties. Manufacturing processes with respect to surface fabrication, encompassing conventional machining, microfabrication and nanomanipulation are only briefly mentioned. Further developments in surface metrology at micro and nanoscale are strongly required for future progress of precision Engineering, microengineering, and nanotechnology; and their fundamental importance can not be overestimated.

10 illus, 1 table, 24 ref

001090   Chowdhury D;Stauffer D (Phys Dep, Indian Inst of Technol, Kanpur-208 016, Email: debch@iitk.ac.in) : Evolutionary ecology in silico: Does mathematical modelling help in understanding `generic' trends?. J Biosci, Bangalore 2005, 30(2), 277-87.

Motivated by the results of recent laboratory experiments, as well as many earlier field observations, that evolutionary changes can take place in ecosystems over relatively short ecological time scales, several 'unified' mathematical models of evolutionary ecology have been developed over the last few years with the aim of describing the statistical properties of data related to the evolution of ecosystems. Moreover, because of the availability of sufficiently fast computers, it has become possible to carry out detailed computer simulations of these models. For the sake of completeness and to put these recent developments in perspectrve, begins with a brief summary of some older models of ecological phenomena and evolutionary processes. Review critically these 'unified' models, particularly those published in the physics literature, in simple language that makes the new theories accessible to a wider audience.

4 illus, 137 ref

001089   Castellini H;Yudiarsah E;Romanelli L;Cerdeira H A (Dep de Fisica, F C E I A, Pellegini 250, 2000 Rosario, Argentina, Email: hcaste@fceia.unr.edu.ar) : Coupled chaotic oscillators and their relation to a central pattern generator for artificial quadrupeds. Pramana J Phys 2005, 64(4), 525-34.

Animal locomotion employs different periodic patterns known as animal gaits. In 1993, Collins and Stewart recognized that gaits possessed certain symmetries and characterized the gaits of quadrupeds and bipeds ufing permutation symmetry groups, which impose constraints on the locomotion center called the central pattern generator (CPG) in the animal brain. They modeled the CPG by coupling four nonlinear oscillators and found that it was possible to reproduce all symmetries of the gaits by changing the coupling strength. Here we propose to extend this idea using coupled chaotic oscillators synchronized using the Pyragas method in order to characterize the CPG symmetries. Authors has also evaluate the time series behavior when the foot is in contact with the ground: this has potential robotic applications.

6 illus, 1 table, 19 ref