008800   Das A K;Das P P;Mukhopadhyay S (Dep of Phys and Technophysics, Vidyasagar Univ, Midnapore-721 102, Email: das_archan2@rediffmail.com) : A new approach of binary addition and subtraction by non-linear material based switching technique. Pramana J Phys 2005, 64(2), 239-47.

Refer a new proposal of binary addition as well as subtraction in all-optical domain by exploitation of proper non-linear material-based switching technique. Extends this technique for both adder and subtracter accommodating the spatial input encoding system.

8 illus, 3 tables, 17 ref

008799   Chowdhary D (Dep of Phys, Indian Inst of Technol, Kanpur-208 016, Email: debch@iitk.ac.in) : 100 years of Einstein's theory of brownian motion:from pollen grains to protein trains-1. Resonance 2005, 10(9), 63-78.

Experimental verification of the theoretical predictions made by Albert Einstein in his paper, published in 1905, on the molecular mechanisms of Brownian motion established the existence of atoms. In the last 100 years Brownian motion has not only revolutionized our fundamental understanding of the nature of thermal fluctuations in physical systems, but it has also explained many counterintuitive phenomena in earth and environmental sciences as well as in life sciences. Describes a brief historical survey and an introduction to the concepts and theoretical techniques for studying Brownian motion. Then, a discussion on rotational Brownian motion and Brownian shape fluctuations of soft materials is followed by an elementary introduction to two of the hottest topics in this contemporary area of interdisciplinary research, namely, stochastic resonance and Brownian ratchet.

12 ref

008798   Choudhury D K;Sahariah P K (Dep of Phys, Gauhati Univ, Guwahati-781 014, Email: pksahariah@hotmail.com) : The next-to-leading order (NLO) gluon distribution from DGLAP equation and the logarithmic derivatives of the proton structure function F₂(x,Q<. Pramana J Phys 2005, 65(2), 192-213.

At low x, an analytic solution of the DGLAP equation for gluon in the next-to-leading order (NLO) is obtained by applying the method of characteristics. Its compatibility with double leading logarithmic approximation (DLLA) asymptotics is discussed and comparison with the exact ones like GRV98NLO is made. The solution is then utilized to calculate the derivatives ∂ F_{2(x,Q²)/∂ in Q² and ∂ in F2(x,Q²)/∂ in (1/x) and compared with the recent HERA data. The solution is found to reproduce most of the essential features of the data on the derivatives.}

5 illus, 37 ref

008797   Choubisa R;Sud K K (Dep of Phys Coll of Sci Campus, M.L.S. Univ, Udaipui-313 002, Email: kksud@yahoo.com) : Quasi-binary incident electron-centre of mass collision in (e, 3e) process on He and He-like ions. Pramana J Phys 2005, 65(1), 85-93.

Results of the first Born calculation in the three-Coulomb (3C) wave approach for the (e,3e) process on He and He-like ions at an incident electron energy 5599 eV in the coplanar constant θ₁₂ as well as out-of-plane constant φ₁₂ modes. These two geometrical modes are such that the quasi-binary collision between the incident electron and centre of mass of the ejected electrons is in the scattering plane. The theoretical formalism has been developed using plane waves, Le Sech wave function and approximated BBK-type wave function respectively for the incident and scattered, bound and ejected electrons to calculate five-fold differential cross-section (FDCS) of the (e, 3e) process. Emphasizes on the similarities and dissimilarities (asymmetries) in the angular profile of the FDCS in two modes as well as the effects of post-collision interaction (between the ejected electrons) and nuclear charge Z on the angular profile of the FDCS. It is observed that with the increment of nuclear charge the two quasi-binary collisions approach towards identical behaviour at larger mutual angles and thus bringing less asymmetry in FDCS for higher Z target.

3 illus, 16 ref

008796   Choi J R (Dep of New Material Sci Div of Nat Sci, Sun Moon Univ, Asan 336-708, Email: choiardor@hanmail.net) : Quantum states with continuous spectrum for a general time-dependent oscillator. Pramana J Phys 2005, 65(2), 165-76.

Investigat quantum states with continuous spectrum for a general time-dependent oscillator using invariant operator and unitary transformation methods together. The form of the transformed invariant operator by a unitary operator is the same as the Hamiltonian of the simple harmonic oscillator: I' = p²/2 + w²q²/2. The fact that w² of the transformed invariant operator is constant enabled us to investigate the system separately for three cases, where w² <62> 0, w² <60> 0, and w² = 0. The eigenstates of the system are discrete for w² <62> 0. On the other hand, for w² <60> 0, the eigenstates are continuous. The time-dependent oscillators whose spectra of the wave function are continuous are not oscillatory. The wave function for w² < 0 is expressed in terms of the parabolic cylinder function. Applie theory to the driven harmonic oscillator with strongly pulsating mass.

39 ref

008795   Chatterjee S;Vani V C (NO, Indian Inst of Astrophys, Bangalore-560 034, Email: chat@iiap.ernet.in) : Scattering of light by a periodic structure in the presence of randomness IV. Limit of detection by curve fitting. Pramana J Phys 2005, 65(3), 413-24.

In the context of scattering of light, determines the extent of randomness within which a hidden periodic part can still be detected. The detection is carried out using a technique called the extended, matched filtering, first introduced by us in this context. The earlier prediction, before the technique was introduced, had placed the limit of detection, by intensity measurements alone, at (r₀/Λ) ≈ 0.33, where r₀ is the coherence length of light for scattering by the rough part of the surface and Λ is the wavelength of the periodic part of the surface. In earlier works shown that by intensity measurements alone, the limit of detection can be taken to a much lower value of (r₀/Λ), when the extended matched filtering method is employed. Follows the extended matched filtering method, and try to reach the lowest possible value of detection in (r₀/Λ) by fitting the data to a polynomial. It is concluded by the numerical work that the lowest possible limit for detection from intensity measurements alone is (r₀/Λ) = 0.11

4 illus, 2 tables, 11 ref

008794   Bhatti H S;Sharma R;Verma N K (Dep of Phys, Punjabi Univ, Patiala-147 002, Email: drhsbhatti03@yahoo.co.in) : Laser-induced down-conversion parameters of singly and doubly doped ZnS phosphors. Pramana J Phys 2005, 65(3), 541-6.

Singly and doubly doped ZnS phosphors have been synthesized using flux method. Laser-induced photoluminescence has been observed in ZnS-doped phosphors when these were excited by the pulsed UV N₂ laser radiation. Due to down-conversion phenomenon, fast phosphorescence emission in the visible region is recorded in milliseconds time domain for ZnS:Mn while in the case of ZnS:Mn:killer (Fe, Co and Ni) the lifetime reduces to microseconds time domain. Experimentally observed luminescent emission parameters of excited states such as, lifetimes, trap-depth values and decay constants have been reported at room temperature. The high efficiency and fast recombination times observed in doped ZnS phosphors make these materials very attractive for optoelectronic applications.

2 illus, 1 table, 13 ref

008793   Banyal R K;Prasad B R (Indian Inst of Astrophys, Koramangala 2nd Block, Bangalore-560 034, Email: brp@iiap.res.in) : Pixel size and pitch measurements of liquid crystal I spatial light modulator by optical diffraction. Pramana J Phys 2005, 65(2), 291-6.

Present a simple technique for the determination of pixel size and pitch of liquid crystal (LC) based spatial light modulator (SLM). The proposed method is based on optical diffraction from pixelated LC panel that has been modeled as a two-dimensional array of rectangular apertures. A novel yet simple, two-plane measurement technique is implemented to circumvent the difficulty in absolute distance measurement. Experimental results are presented for electrically addressed twisted nematic LC-SLM removed from the display projector.

5 illus, 9 ref

008792   Bali R;Yadav M K (Dep of Math, Univ of Rajasthan, Jaipur-302 004) : Bianchi Type-IX viscous fluid cosmological model in general relativity. Pramana J Phys 2005, 64(2), 187-96.

Bianchi Type-IX viscous fluid cosmological model is investigated. To get a deterministic model, assum the condition a = b^m (m is a constant) between metric potentials and η ∝ ϑ where η is the coefficient of shear viscosity and ϑ the scalar of expansion in the model. The coefficient of bulk viscosity (ζ) is taken as constant. The physical and geometrical aspects of the model are also discussed.

17 ref

008791   Anand Kumar (Cent for Math Modelling and Computer Simulation, CSIR, Banglore-560 037, Email: kumar@cmmacs.erent.in ) : Noise removal in images using isotropic finite-differences. Curr Sci 2005, 88(5), 700-1.

3 ref

008790   Ahuja B L;Sharma M (Dep of Phys, Coll of Sci Campus ML. Sukhadia Univ, Udaipur-313 001, Email: blahuja(c)yahoo.com ) : Performance of 20 Ci <. Pramana J Phys 2005, 65(1), 137-45.

Presents the design and construction of a 20 γ-ray Compton spectrometer that employs a ¹³⁷Cs source with a strong line at 661.65 keV. The total resolution of the spectrometer in momentum scale is 0.40 a.u., which is much better than the conventional ²⁴¹Am Compton spectrometers. The in-house ¹³⁷Cs spectrometer is very useful for the measurement of momentum densities of heavy materials. The performance of the machine is assessed using aluminum, terbium and mercury samples and the experimental data from comparable apparatus.

4 illus, 1 table, 16 ref

008789   Ahmad I;Abdulmomen M A;Hamra G A (Dep of Phys Fac of Sci, King Abdulaziz Univ, P.O. Box 80203, Jeddah, Saudi Arabia, Email: iahmad@kaau.edu.sa) : Optical model potential of 800 MeV/c K<. Pramana J Phys 2005, 65(3), 523-8.

The elastic scattering differential cross-sections of 800 MeV/c K⁺ mesons from ¹²C and ⁴⁰Ca have been analyzed using the Ericson's parametrization for the phase shift. It is found that the parameter values obtained by analysis are significantly different from those obtained from the closed expression for K⁺- nucleus amplitude derived by the strong absorption approximation. Next, using the phase shift obtained from the present analysis calculate the K⁺ optical model potentials for ¹²C and ⁴⁰Ca by the method of inversion. The calculated potentials are compared with the recently determined phenomenological ones.

5 illus, 11 ref

008788   Adebayo G A;Akinlade O;Malomo O A;Hussain L A (NO, The Abdus Salam Int Cent for Theoretical Phys, Trieste, Italy, Email: gadebayo@ictp.trieste.it) : Structure, single-particle and many-particle coefficients of Lennard-Jones liquid A1. Pramana J Phys 2005, 65(2), 339-47.

Investigate the effects of temperature and density on the single-particle and many-particle coefficients as well as on the structures of homogenous systems in which the particles are assumed to interact via a continuous soft sphere potential in the microcanonical ensemble. The pair distribution function and therefore the structures of the systems studied are affected by temperature close to and above the melting point through migrations of atoms from the first shell in the pair distribution function. The dynamics of atomic pairs in the short-time regime in liquid aluminium may be said to be governed by the potential of mean force, which depends on the static structure of liquid Al at all investigated temperatures. A polynomial dependence of D on density and temperature was observed in contradiction to Arrhenius law. The shear viscosities of the systems studied are largely nonlinear. It was observed that the soft sphere potential used in the calculations overestimates the Stoke-Einstein relation.

5 illus, 1 table, 11 ref

008787   Adebayo G A;Akinlade O;Hussain L A (NO, The Abdus Salam Int Cent for Theoretical Phys, Trieste, Italy, Email: gadebayo@ictp.trieste.it) : Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation. Pramana J Phys 2005, 64(2), 269-79.

The structures and autocorrelation functions of Al and Mg in the liquid state are investigated through the pair distribution function g(r), the diffusion coefficients as well as the shear viscosity via the Green-Kubo and Einstein relations. Prom the structure and the Enskog relation its determined the frequency of collisions of atoms in the first shell of g(r) in the systems. authors also discovered that the packing fraction of Lennard-Jones liquids should be approximately half the reduced density value. This approximation is accurate to within 99%. The temperature dependence of the pair distribution function and the atomic mean square displacement are investigated by performing simulations at various experimental temperatures and corresponding densities. The structures of the systems are affected by temperature via movements of atoms in the first minimum of g(r). The Lennard-Jones model shows that density dependence of the shear viscosity is in agreement with what is expected of simple liquids in the range of investigated temperatures and densities. In the gas limit, the Stoke-Einstein relation Dη = K_BT/2-πσ is grossly overestimated by Lennard-Jones model. This could not be attributed to deficiencies in the model, as other investigators using first principle method could not obtain the gas limit of the Stoke-Einstein relation.

6 illus, 4 tables, 23 ref

007722   Sahoo S (Dep Phys, National Institute of Technology, Durgapur-713 209, Email: sukadevsahoo@yahoo.com) : Three-fourth of everything: the standard model. Phys Educ 2005, 22(2), 85-111.

In recent years, high energy physicists have arrived at a picture of the microscopic physical Universe, called "The Standard Model", which unifies the strong, electromagnetic, and weak forces. This model enumerates the fundamental building blocks of the universe. This model does not take into account the gravitational forces. Without gravity the Standard Model is seriously incomplete. This is why "String Theory" comes into picture.

8 illus, 4 tables, 18 ref

007721   Pande R;Kalamse G M (Dept. Phys, N.E.S. Science College, NANDED-431 605) : Dielectric behaviour of binary mixtures of propane diol with ethylene diamine. Int J chem Sci 2005, 3(1), 155-60.

Density, viscosity, refractive index, dielectric constant (∈') and dielectric loss (∈") of propane diol, ethylene diamine and their mixtures for different mole fraction of ethylene diamine have been measured at 9.84 GHz and temperature 22°C. From the experimental data, molar polarization (P₁₂), apparent polarization (P₂) and the excess values of permittivities (Δ∈") square refractive index (n_D²), viscosity (Δη) and activation energy (ΔE_a) of viscous flow are estimated. These parameters have been used to explain the formation of complexes in the system.

4 illus, 3 tables, 12 ref

007720   Pa S K;Ray H S;Choudnury P;Das S;Majumdar M (NO, Central Glass and Ceramic Research Institute, Kolkata-700 032, Email: hs_ray@yahoo.com) : Approach towards theoretical prediction of viscosity of glasses over a wide range of temperature. Trans Indian Ceramic Soc 2005, 64(2), 81-6.

A model for estimation of viscosities of glass melts at relatively high temperatures has been previously reported from this laboratory. The paper describes an approach for extension of the model to relatively low temperatures. In addition, another novel method for estimation of viscosity over a wide temperature range is presented. Viscosity data on several commercially important glasses are reported to discuss the applicability of these models, all of which employ Optical Basicity (OB) of the system as a compositional parameter.

10 illus, 3 tables, 14 ref

007719   Datta B;Bhattacharji J K (NO, S.N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata-700 098) : Ehrenfest's equation for the hydrogen atoms passage to the Kepler orbit. Phys Educ 2005, 22(2), 139-44.

Treat the Ehrenfest's equation for the radial coordinate of a hydrogen atom in the limit of the large angular momentum. It is shown explicitly that the quantum fluctuation disappears for large angular momenta for wavepackets that follow the classical orbit and Ehrenfest's equation reproduces exactly the Kepler orbit. This provides a clear demonstration of the Correspondence Principle.

10 ref

007718   Buddhudu S (Dept Physcis, Sriv Venkateswara University, Tirupati-517 502, Email: profsb_svuniv@hotmail.com) : Emission analysis of rare earth (Pr<. Trans Indian Ceramic Soc 2005, 64(2), 69-80.

The article reports on the newly developed heavy metal based multicomponent ZrF₄-BaF₂-LaF₃-YF₃-AIF₃-NaF optical glass systems, which are abbreviated as ZBLYAN glasses for easy reference. These host glass matrices have been doped with rare earth ions such as Pr³⁺ or Dy³⁺ or Tm³⁺ to understand their upconverted emission phenomenon and normal emission as well through a systematic approach. NIR upconversion emissions into visible colours have been reported from these rare earth ions doped optical fibre core based standard glass compositions. The possible mechanisms involved in such upconversion emission processes have been explained more clearly in terms of energy levels schemes.

17 illus, 3 tables, 39 ref

007717   Adgaonkar C S;Mahajan M A;Naphade V L;Thakre J B (Dep Electron, Nagpur University, Nagpur-440 033) : Measurement of thermal expansion of solids by optical method. Phys Educ 2005, 22(2), 113-18.

A Simple apparatus based on optical method is designed for the measurement of coefficient of thermal expansion (a) of solids. The experimental values of a for Al, Cu, etc and Gruneisen parameter values obtained for NaCl, KCl agree well with the literature values, The apparatus can be used for P. G. experiments.

5 illus, 2 tables, 7 ref

006645   Yakimov E B (NO, Inst of Microelectronics Technol RAS, Chernogolovka-142 432, Russia) : EBIC and DLTS characterization of pure Si2 crystals. Bull Mater Sci 2005, 28(4), 367-71.

Possibilities of measurements of low defect concentration in Si by the electrical methods are discussed. The problems arising in such measurements are illustrated by measurements of iron concentration in Si. It is demonstrated that gold diffusion experiments can be used for revealing and study of some electrically inactive defects. Possibility of nondestructive reconstruction of defect depth profiles by DLTS and using the profile obtained for understanding the defect nature is illustrated by the results of hydrogen and hydrogen related defect investigations. EBIC investigations of dislocations are shown to be a rather sensitive method for revealing recombination defects.

9 illus, 18 ref

006644   Yadunath Singh;Goswami D P;Kalra M L (Dep Phys, Mohanlal Sukhadia Univ, Udaipur-313 001) : Non-linear conduction and switching phenomena in quasi-one dimensional compounds. Int J chem Sci 2005, 3(2), 325-32.

Quasi one dimensional compounds of Radical Ion-Salts (RIS) type like Qn-(TCNQ)2, Ad-(TCNQ)2, K-TCNQ, and Cu2O-TCNQ, were synthesized using different methods like electrochemical, diffusion and solution growth methods. The single crystals of Qn-(TCNQ)2 and Ad-(TCNQ)2 grown by electrochemical method were found to be largest in size (length) reported so far. The room temperature conductivity of these compounds was found to be in a wide range of 10^-4 to 10² ohm^-1 cm^-1. For RIS with symmetric cations like K-TCNQ and Cu2O-TCNQ, it was found that log σ α T^<-97> as is observed in conventional semiconductors. Besides these, semiconductor-metal phase transitions with temperature were observed. The investigation of the I-V characteristics of the four RIS synthesized were carried out in temperature range 10 to 300 K. All the four compounds show ohmic behaviour at low currents and transition to non-ohmic region at higher currents. In some cases (Qn-TCNQ2 and K-TCNQ) a negative differential resistance region at higher currents was observed. In RIS with symmetric cations (K-TCNQ and Cu2O-TCNQ), switching phenomena was observed at some particular temperatures.

6 illus, 25 ref

006643   Wiese K J (Laboratoire de Physique Theorique, Ecole Normale Superieure, 24 rue Lhomond, 75005 Paris, France, Email: wiese@corto.lpt.ens.fr) : Why one needs a functional renormalization group to survive in a disordered world. Pramana J Phys 2005, 64(5), 817-27.

In the paper, Authors discuss why functional renormalization is an essential tool to treat strongly disordered systems. More specifically, It treat elastic manifolds in a disordered environment. These are governed by a disorder distribution, which after a finite renormalization becomes non-analytic, thus overcoming the predictions of the seemingly exact dimensional reduction. Authors discuss how a renormalizable field theory can be constructed even beyond 2-loop order. It then consider an elastic manifold embedded in N dimensions, and give the exact solution for N→ ∞. This is compared to predictions of the Gaussian replica variational ansatz, using replica symmetry breaking. Finally, the effective action at order 1/N is reported.

5 illus, 1 table, 26 ref

006642   Verma K K;Soni K R (Microwave Lab Dep Phys, Malaviya Natn Inst of Technol, Jaipur-302 017, Email: kkvermaphd@rediffmail.com) : Theoretical study of 2 x 2 element planar array of equilateral triangular patch microstrip antenna in plasma medium. Pramana J Phys 2005, 64(1), 147-52.

The radiation properties of 2 x 2 element planar array of equilateral triangular patch microstrip antenna in plasma medium are studied. The array factor and far-zone EM-mode and P-mode radiation fields of the array geometry are derived using vector wave function techniques and pattern multiplication approaches. The total field patterns and various characteristics of pattern such as half power beam width (HPBW), first null beam width (FNBW) and direction of maximum radiation are computed for two different values of progressive phase excitation difference between the elements. The results of this array geometry are obtained both in plasma medium and in free space and compared with those of single element equilateral triangular patch microstrip antenna.

6 illus, 1 table, 6 ref

006641   Stanley H E (Dep Phys Cent Polym Stud, Boston Univ, Boston, MA 02215, USA, Email: hes@bu.edu) : Correlated randomness: some examples of exotic statistical physics. Pramana J Phys 2005, 64(5), 645-60.

One challenge of biology, medicine, and economics is that the systems treated by these scienceshave no perfect metronome in time and no perfect spatial architecture - crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. To understand this 'miracle', one might consider placing aside the human tendency to see the universe as a machine. Instead, one might address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at many spatial and temporal patterns in biology, medicine, and economics. Inspired by principles developed by statistical physics over the past 50 years - scale invariance and universality - Author review some recent applications of correlated randomness to fields that might startle Boltzmann if he were alive today.

11 illus, 25 ref

006640   Srivastava M K (Inst Instrumentation Cent, Indian Inst of Technol, Roorkee-247 667, Email: mksrific@iitr.ernet.in) : Scaling of triple differential cross sections for asymmetric (e, 2e) process on helium isoelectronic ions by fast electrons. Pramana J Phys 2005, 64(1), 55-66.

A simple scaling law is obtained for asymmetric (e, 2e) process on helium isoelectronic ions by fast electrons. It is based on treating the targets as having one active electron moving in the effective Coulomb field of the atomic core with an effective charge Z' = Z - 5/8. This effective charge is also used in the description of the scattered and ejected electrons. The model has been tested against other available (e, 2e) results on helium in asymmetric geometry. The scaling law is found to work reasonably well for fast incident electrons and becomes increasingly accurate as target Z increases.

6 illus, 2 tables, 31 ref

006639   Singh N;Anand Kumar;Mishra V (Dep Phys, Nehru Coll, Chhibramau -209 721) : Effect of external electric field on critical parameters and equivalence between the electric field and supersaturation ratio during water vapour condensation and ice glaciation. Natn Acad Sci Lett 2004, 27(9-10), 357-64.

In presence of an external electric field water droplets have been found to grow with time. Theory of droplet growth in presence of external electric field has been applied to nucleation phenomenon of water vapour condensation and ice glaciation. The phase change depends on temperature and supersaturation ratio. In the study, the radius of critical nucleus, number of water molecules in it and Gibbs' free energy of its formation have been calculated as the function of temperature and supersaturation ratio. These parameters have also been calculated in presence of external electric field as the function of electric field and relaxation time. The parameters in presence of electric field have been found much less than those obtained in electric field free case, but the equilibrium concentration of nuclei is very much larger. The equivalence between external electric field and supersaturation ratio suggests that small value of electric field is equivalent to very high supersaturation ratio to get nucleus of given size under similar conditions of temperature.

^ssc2 illus, 1 table, 19 ref

006638   Singh N (Optics Grp, Raman Res Inst, Banglore-560 080, Email: navinder@rri.res.in) : Relaxation of femtosecond photoexcited electrons in a polar indirect band-gap semiconductor nanoparticle. Pramana J Phys 2005, 64(1), 111-8.

A model calculation is given for the energy relaxation of a non-equilibrium distribution of hot electrons (holes) prepared in the conduction (valence) band of a polar indirect band-gap semiconductor, which has been subjected to homogeneous photoexcitation by a femtosecond laser, pulse. The model assumes that the pulsed photooexcitation creates two distinct but spatially interpenetrating electron and hole non-equilibrium subsystems that initially relax non-radiatively through the electron (hole)-phonon processes towards the conduction (valence) band minimum (maximum), and finally radiatively through the phonon-assisted electron-hole recombination across the band-gap, which is a relatively slow process. This leads to an accumulation of electrons (holes) at the conduction (valence) band minimum (maximum). The resulting peaking of the carrier density and the entire evolution of the hot electron (hole) distribution has been calculated. The latter may be time resolved by a pump-probe study. The model is particularly applicable to a divided (nanometric) polar indirect band-gap semiconductor with a low carrier concentration and strong electron-phonon coupling, where the usual two-temperature model [1-4] may not be appropriate.

7 illus, 4 ref

006637   Shrivastava K N (Sch Phys, Univ of Hyderabad, Hyderabad- 500046) : Unification of charge of the electron with proton and neutron through quantum Hall effect. Natn Acad Sci Lett 2004, 27(11-12), 435-40.

In the Dirac equation there are solutions such that one particle is negatively charged and the other is positively charged. A particle of zero charge can also be introduced. The sum of the three charges is zero. Author has reported that it is possible to have the sum of the charges equal to zero by using fractions. Similarly, l+s, is conserved in the Dirac equation but l-s, is not. Author has used negative spin for the spin so that l-s, is conserved. Author found that there is a contribution to the charge. This means that spin of the electron behaves like the charge. This phenomenon is well known for neutron and proton which have charges of 0 and +1, but it is new for the electron. Representation of ±1/3 and ±2/3 still adds to zero as does the 0, ±1 except that now there are four particles where there were only 3.

^ssc10 ref

006636   Shivarudrappa V;Vimalnath K V (Radiopharmaceuticals Div, Bhabha Atom Res Cent, Mumbai-400 085, Email: vshiva@magnum.barc.ernet.in) : High purity materials as targets for radioisotope production: Needs and challenges. Bull Mater Sci 2005, 28(4), 325-30.

Radionuclides have become powerful and indispensable tools in many endeavours of human activities, most importantly in medicine, industry, biology and agriculture, apart from R&D activities. Ready availability of radionuclides in suitable radiochemical form, its facile detection and elegant tracer concepts are responsible for their unprecedented use. Application of radioisotopes in medicine has given birth to a new branch, viz. nuclear medicine, wherein radioisotopes are used extensively in the diagnosis and treatment of variety of diseases including cancer. Artificial transmutation of an element employing thermal neutrons in a reactor or high energy particle accelerators (cyclotrons) are the routes of radioisotope production world over. Availability of high purity target materials, natural or enriched, are crucial for any successful radioisotope programme. Selection of stable nuclides in suitable chemical form as targets with desired isotopic and chemical purity are among the important considerations in radioisotope production. Mostly the oxide, carbonate or the metal itself are the preferred target forms for neutron activation in a research reactor. Chemical impurities, particularly from the elements of the same group, put a limitation on the purity of the final radioisotope product. Whereas the isotopic impurities result in the production of undesirable radionuclidic impurities, which affect their effective utilization. Isotope Group, BARC, is in the forefront of radioisotope production and supply in the country, meeting demands for gamut of radioisotope applications indigenously for over four decades now. Radioisotopes such as ¹³¹I, ⁹⁹Mo, ³²P, ⁵¹Cr, ¹⁵³Sm, ⁸²Br, ²⁰³Hg, ¹⁹⁸Au etc are produced in TBq quantities every month and supplied to several users and to Board of Radiation and Isotope Technology (BRIT). Such a large production programme puts a huge demand on the reliable sources of availability of high purity target materials which are at present mostly met through import. Availability of suitable target materials, their purity considerations and our efforts in finding sources of raw materials for sustaining the radioisotope programme are discussed here.

1 illus, 3 tables, 5 ref

006635   Seikh M M;Sood A K;Narayana C (Chem Phys Mater Unit, Jawaharlal Nehru Cent for Advd Scientific Res, Jakkur, P.O., Bangalore-560 064) : Electronic and vibrational Raman spectroscopy of Nd_0.5Sr_0.5MnO₃ through the phase transitions. Pramana J Phys 2005, 64(1), 119-28.

Ram scattering experiments have been carried out on single crystals of Nd0.5 Sr 0.5MnOa as a function of temperature in the range of 320-50 K, covering the paramagnetic insulator-ferromagnetic .metal transition at 250 K and the charge-ordering antiferromagnetic transition at 150 K. The diffusive electronic Raman scattering response is seen in the paramagnetic phase which continue to exist even in the ferromagnetic phase, eventually disappearing below 150 K. Authors understand the existence of diffusive response in the ferromagnetic phase to the coexistence of the different electronic phases. The frequency and linewidth of the phonons across the transitions show significant changes, which cannot be accounted for only by anharmonic interactions.

3 illus, 29 ref

006634   Sastry S V S;Kailas S;Mohanty A K;Saxena A (Nuclear Phys Div, Bhabha Atom Researach Cent, Trombay, Mumbai-400 085) : Adiabatic heavy-ion fusion potentials for fusion at deep sub-barrier energies. Pramana J Phys 2005, 64(1), 47-53.

The recently reported unusual behaviour of fusion cross-sections at extreme sub-barrier energies has been examined. The adiabatic limit of fusion barriers has been determined from experimental data using the barrier penetration model. These adiabatic barriers are consistent with the adiabatic fusion barriers derived from the modified Wilzynska-Wilzynski prescription. The fusion barrier systematic has been obtained for a wide range of heavy-ion systems.

2 illus, 1 table, 17 ref

006633   Santra A B;Lombardo U (Nuclear Phys Div, Bhabha Atom Res Cent, Mumbai-400 085, Email: santra@apsara.barc.ernet.in) : Nuclear matter equation of state and σ-meson parameters. Pramana J Phys 2005, 64(1), 31-7.

Author has try to determine phenomenologically the extent of in-medium modification of σ-meson parameter so that the saturation observables of the nuclear matter equation of state(EOS)are reproduced. To calculate the EOS author has used Brueckner-Bethe-Goldstone formalism with Bonn potential as two-body interaction. Author has find that it is possible to understand all the saturation observables, namely, saturation density, energy per nucleon and incompressibility, by incorporating in-medium modification of σ-meson-nucleon coupling constant and σ-meson mass by a few percent.

2 illus, 1 table, 22 ref

006632   Santosh K P;Joseph A (Dep Phys, Payyanur Coll, Payyanur-670 327, Email: kpsanthosh@eth.net) : Cluster emission in superdeformed Sr isotopes in the ground state and formed in heavy-ion reaction. Pramana J Phys 2005, 64(1), 39-46.

Clusterster decay of superdeformed ^{76, 78, 80}Sr isotopes in their ground state are studied taking the Coulomb and proximity potential as the interacting barrier for the post-scission region. The predicted T_1/2 values are found to be in close agreement with those values reported by the preformed cluster model (PCM). Calculation shows that these nuclei are stable against both light and heavy cluster emissions. Authors have studied the decay of these nuclei produced as an excited compound system in heavy-ion reaction. It is found that inclusion of excitation energy increases the decay rate (decreases T_1/2 value) considerably and these nuclei become unstable against decay. These findings support earlier observation of Gupta et al based on PCM.

3 illus, 2 tables, 32 ref

006631   R Pavela (NO, Res Inst of Crop Production, Drnovska 507, 161 06 Praha 6-Ruzyne, Czech Republic, Email: pavela@vurv.cz ) : Repellent effect of ethanol extracts from plants of the family Lamiaceae on Colorado potato beetle adults Leptiriotarsa decemlineata SAY. Natn Acad Sci Lett 2004, 27(5-6), 195-203.

The effect of ethanol extracts, from 9 plants of the family Lamiaceae applied on potato leaves, on the feeding behaviour of adult individuals of Colorado potato beetle was studied in laboratory. Extracts of Salvia splendens, Origanum majorana, Hyssopus officinalis, Salvia officinalis and Marrubium vulgare were strongly repellent (84-98% repellency). Thymus vulgaris, Ocimum bassilicum and Origanum vulgare showed a medium repellency (61-74%) and Mellisa officinalis had a weak repellency (28%). After 24 and 48 hours there were 50 and 90%, respectively, of control leaves eaten. Leaves with extracts of S. splendens, O. majorana, H. officinalis, S. officinalis and M. vulgare showed long antifeedant activity as they were not eaten at all or a little (less than 7%) even after 48 hours of exposure. Leaves treated by T vulgaris and O. bassilicum had a medium antifeedant activity - eaten by less than 28%. Finally, leaves treated by O. vulgare and M. officinalis showed weak antifeedant effect as being eaten by 46-71%.

^ssc4 graph, 1 table, 19 ref

006630   Patidar V;Sud K K (Dep Phys, Coll of Sci Campus M.L.S. Univ, Udaipur-313 002, Email: vinod_r_patidar@yahoo.co.in) : Bifurcation and chaos in simple jerk dynamical systems. Pramana J Phys 2005, 64(1), 75-93.

In recent years, it is observed that the third-order explicit autonomous differential equation, named as jerk equation, represents an interesting sub-class of dynamical systems that can exhibit many major features of the regular and chaotic motion. The global dynamics of a special family of jerk systems x^...=-Ax^..-x^.+G(x), where G(x) is a non-linear function, which are known to exhibit chaotic behaviour at some parameter values have been investigated. The regions of parameter space with different asymptotic dynamics using some analytical methods as well as extensive Lyapunov spectra calculation in complete parameter space have been identified. The effect of weakening as well as strengthening of the non-linearity in the G(x) function on the global dynamics of these jerk dynamical systems have been investigated. An important conclusion has been reached for these jerk dynamical systems that a certain amount of non-linearity is sufficient for exhibiting chaotic behaviour but increasing the non-linearity does not lead to larger regions of parameter space exhibiting chaos.

9 illus, 1 table, 35 ref

006629   Panicker C Y;Anto P L;Varghese H T;Philip D (Dep Phys, TKM Coll of Arts and Sci, Kollam-691 005) : Surface selection rules of surface enhanced Raman scattering. Int J chem Sci 2005, 3(2), 268-70.

Surface Enhanced Raman Scattering (SERS) is an important spectroscopic tool for studying molecules adsorbed on noble metal surfaces. The surface selection rules for SERS are discussed.

23 ref

006628   Onuki A;Furukawa A;Minami A (Dep Phys, Kyoto Univ, Kyoto-606 8502, Japan, Email: onuki@scphys.kyoto-u.ac.jp) : Sheared solid materials. Pramana J Phys 2005, 64(5), 661-77.

Time-dependent Ginzburg-Landau model of nonlinear elasticity in solid materials. Author Assume that the elastic energy density is a periodic function of the shear and tetragonal strains owing to the underlying lattice structure. With this new ingredient, solving the equations yields formation of dislocation dipoles or slips. In plastic flow high-density dislocations emerge at large strains to accumulate and grow into shear bands where the strains are localized. In addition to the elastic displacement, Author also introduce the local free volume m. For very small mthe defect structures are metastable and long-lived where the dislocations are pinned by the Peierls potential barrier. However, if the shear modulus decreases with increasing m, accumulation of m around dislocation cores eventually breaks the Peierls potential leading to slow relaxations in the stress and the free energy (aging). As another application of scheme, Author also study dislocation / formation in two-phase alloys (coherency loss) under shear strains, where dislocations glide preferentially in the softer regions and are trapped at the interfaces.

11 illus, 44 ref

006627   Narendra Singh;Man Mohan (NO, , B 339, Gali NO. 4, Majlish Park, Delhi-110 033, Email: nsingh76@yahoo.co.in) : Collisional excitation of neon-like Ni XIX using the Breit-Pauli R-matrix method. Pramana J Phys 2005, 64(1), 129-34.

Collision strength for the transition within the first five fine-structure levels in Ni XIX are calculated using the Breit-Pauli R-matrix method. Configuration interaction wave function are used used to represent the target states included in the R-matrix expansion. The relativistic effects are incorporated in the Breit-Pauli approximation by including the one-body mass correction, Darwin and spin-orbit interaction terms in scat-tering equations.

5 illus, 1 table, 11 ref

006626   Mukesh Kumar (Dep Phys, B.R.A. Bihar Univ, Muzaffarpur-842 001) : Estimation of stimulated raman scattering in laser dusty plasma interaction. Oriental J Chem 2005, 21(1), 141-4.

Theoretical investigation has been carried out to evaluate the mechanism of multiple scattering in laser dusty plasma interaction. In this purpose the concept of stimulated Raman and Brillouin scattering in dusty plasma interaction has been utilized. Consequently the expression for scattering and extinction cross-section has been developed. It has been found that the values of scattering cross section, absorption cross section, extinction cross-section increases with increasing value of the frequency of the incident radiation. It is also observed that in the lower range of the frequency the absorption cross-section may represent the extinction cross-section when the frequency is increased the contribution of scattering cross section to the extinction cross-section also.

13 ref

006625   Mukesh Kumar (NO, , Diwakan Bhawar, Mishra Tola, Gannipur, Muzaffarpur-842 001) : Estimation of complex dielectric constant of solid particles from bulk measurement. Int J chem Sci 2005, 3(2), 285-9.

Theoretical investigation has been carried out to evaluate the complex dielectric constant of solid soil particles from bulk measurement data. For this purpose various expressions suggested by different authors have been utilized and from extrapolation the value of complex dielectric constant of solid soil particles has been obtained. It has been found that the value obtained from the extrapolation has good agreement with the reported value of the dielectric constant of moist solid soil particles. Further, using same suggested formula the complex dielectric constant of moist solid soil particles has also been calculated. It has been observed that the value of complex dielectric constant of solid soil particles increases with increasing percentage of moisture content for each sample.

3 tables, 7 ref

006624   Lubensky T C (Dep Phys Astronomy, Univ of Pennsylvania, Philadelphia PA 19104, USA, Email: tom@physics.upenn.edu) : Phenomenological dynamics: from navier-stokes to chiral granular gases. Pramana J Phys 2005, 64(5), 727-42.

Paper reviews the derivation of equations for slow dynamical processes in a variety of systems,including rotating rigid rotors, crystalline solids, isotropic and nematic elastomers, gels in an isotropic fluid background, and nematic liquid crystals . It presents a recent derivation ofthe Leslie-Ericksen equations for the dynamics of nematic liquid crystals that clarifies the nature of the nonhydrodynamic modes in these equations. As a final example of the phenomenological approach to slow dynamical processes, it discusses the dynamics of a driven nonequilibrium system: a two-dimensional gas of chiral 'rattlebacks' on a vibrating substrate.

3 illus, 31 ref

006623   Kumar J (Crystal Growth Cent, Anna Univ, Chennai-600 025, Email: marsjk@annauniv.edu) : Progress in III-nitrides: process issue and purity perspective. Bull Mater Sci 2005, 28(4), 355-60.

The growth of good quality layers of gallium nitride (GaN) as suitable for epitaxial growth is of great technological importance. Chloride vapour phase epitaxy (Cl-VPE) has been employed to grow good quality layers of GaN. The grown layers have been extensively characterized for their structural and optical properties. MOVPE grown GaN layers have been used to address process issues on device structuring and fabrication. GaN samples with different transition metal dopants have been synthesized and their usefulness as semi-magnetic materials, which are also identified as dilute magnetic semiconductors (DMS), have been evaluated. Better results have been obtained on the magnetic characteristics of GaN with ruthenium as the dopant. Nano dimensional structures of GaN have been obtained with excellent control of the growth parameters.

7 illus, 1 table, 10 ref

006622   Krishnan R;Jayannavar A M (Inst Phys, , Sachivalaya Marg, Bhubaneswar-751 005, Email: jayan@iopb.res. in) : Engines at molecular scales. Natn Acad Sci Lett 2004, 27(9-10), 301-13.

In recent literature there has been a lot of interest in the phenomena of noise induced transport in the absence of an average bias occurring in spatially periodic systems far from equilibrium. One of the main motivations in this area is to understand the mechanism behind the operation of biological motors at molecular scale. These molecular motors convert chemical energy available during the hydrolysis of ATP into mechanical motion to transport cargo and vesicles in living cells with very high reliability, adaptability and efficiency in a very noisy environment. The basic principle behind such a motion, namely the Brownian ratchet principle, has applications in nanotechnology as novel nanoparticle separation devices. Also, the mechanism of ratchet operation finds applications in game theory. Here, author has briefly focused on the physical concepts underlying the constructive role of noise in assisting transport at a molecular level. The nature of particle currents, the energetic efficiency of these motors, the entropy production in these systems and the phenomenon of resonance/coherence are discussed.

7 illus, 19 ref

006621   Jivani A R;Trivedi H J;Gajjar P N;Jani A R (Dep Phys, Sardar Patel Univ, Vallabh Vidyanagar-388 120, Email: jivani_a_r@yahoo.com) : Total energy, equation of state and bulk modulus of AIP, AlAs and AlSb semiconductors. Pramana J Phys 2005, 64(1), 153-8.

Recently proposed model potential which combines both linear and quadratic types of interactions is employed for the investigation of some properties like the total energy, equation of state and bulk modulus of AlP, Al As and AlSb semiconductor compound using higher-order perturbation theory. The model potential parameter is determined using zero pressure condition. The ratio of the covalent bonding term E_cov to the second order term E₂ is 6.77% to 11.85% which shows that contribution from higher order terms are important for zinc-blende-type crystals. The calculated numerical results of the total energy, energy band gap at Jones-zone face and bulk modulus of these compounds are in good agreement with the experimental data and found much better than other such theoretical findings. Authors also studied pressure-volume relations of these compounds. The study is carried out using six different screening functions along with latest screening function proposed by Sarkar et al. It is found from the study that effect of exchange and correlation is clearly distinguishable.

3 illus, 4 tables, 22 ref

006620   Jawkar S S;Jha S S (Dep Phys, Indian Inst of Technol, Mumbai-400 076, Email: ssjha@phy.iitb.ac.in) : Mean square number fluctuation for a fermion source and its dependence on neutrino mass for the universal cosmic neutrino background. Pramana J Phys 2005, 64(1), 17-29.

Using the general formulation for obtaining chemical potential μ of an ideal Fermi gas of particles at temperature T, with particle rest mass m₀ and average density <60>N<62>/V, the dependence of the mean square number fluctuation <ΔN²<62>/V on the particle mass too has been calculated explicitly. The numerical calculations are exact in all cases whether rest mass energy m₀c² is very large (non-relativistic case), very small (ultra-relativistic case) or of the same order as the thermal energy k_BT. Application of results to the detection of the universal very low energy cosmic neutrino background (CNB), from any of the three species of neutrinos, shows that it is possible to estimate the neutrino mass of these species if from approximate experimental measurements of their momentum distribution one can extract, someday, not only the density (N_v)/V but also the mean square fluctuation <ΔN²_ν>/V. If at the present epoch, the universe is expanding much faster than thermalization rate for CNB, it is shown that our analysis leads to a scaled neutrino mass m_ν instead of the actual mass m_0ν.

4 illus, 10 ref

006619   Diehl H W (Fachbereich Physik, Universitat Dusburg-Essen, Campus Essen, D-45117 Essen, Germany, Email: phy300@theo-phys.uni-essen.de) : Bulk and boundry critical behavior at lifshitz points. Pramana J Phys 2005, 64(5), 803-16.

Lifshitz points are multicritical points at which a disordered phase, a homogeneous ordered phase, and a modulated ordered phase meet. Their bulk universality classes are described by natural generalizations of the standard φ⁴ model. Analyzing these models systematically via modern field-theoretic renormalization group methods has been a long-standing challenge ever since their introduction in the middle of 1970s. Authors survey the recent progress made in this direction, discussing results obtained via dimensionality expansions, how they compare with Monte Carlo results, and open problems. These advances opened the way towards systematic studies of boundary critical behavior at m-axial Lifshitz points. The possible boundary critical behavior depends on whether the surface plane is perpendicular to one of the m modulation axes or parallel to all of them. Authors show that the semi-infinite field theories representing the corresponding surface universality classes in these two cases of perpendicular and parallel surface orientation differ crucially in their Hamiltonian's boundary terms and the implied bound ary conditions, and explain recent results along with current understanding of this matter.

1 table, 82 ref

006618   Dhar S (Dep Electronic Sci, Univ of Calcutta, Kolkata-700 009, Email: sdhar_25@yahoo.co.in) : Growth of high purity semiconductor epitaxial layers by liquid phase epitaxy and their characterization. Bull Mater Sci 2005, 28(4), 349-53.

Paper briefly describes work and the results on the growth of several III-V epitaxial semiconductor materials in high purity form by liquid phase epitaxy (LPE) technique. Various possible sources of impurities in such growth are listed and step-by-step procedures adopted to reduce them are discussed in particular reference to the growth of GaAs layers. The technique of growing very high purity layers by treating the melt with erbium is described for the growth of InGaAs and GaSb layers.

6 illus, 9 ref

006617   Derrida B (Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris Cedex 05 France, Email: derrida@lps.ens.fr) : Fluctuations and large deviations in non-equilibrium systems. Pramana J Phys 2005, 64(5), 695-707.

For systems in contact with two reservoirs at different densities or with two thermostats at different temperatures, the large deviation function of the density gives a possible way of extending the notion of free energy to non-equilibrium systems. This large deviation function of thedensity can be calculated explicitly for exclusion models in one dimension with open boundary conditions. For these models, one can also obtain the distribution of the current of particles flowing through the system and the results lead to a simple conjecture for the large deviation function of the current of more general diffusive systems.

4 illus, 29 ref

006616   Dasgupta C (Dep Phys Cent Condensed Matter Theory, Indian Inst of Sci, Bangalore-560 012, Email: cdgupta@physics.iisc.ernet.in) : Theoretical approaches to the glass transition in simple liquids. Pramana J Phys 2005, 64(5), 679-94.

Theoretical approaches to the development of an understanding of the behaviour of simple supercooled liquid near the structural glass transition are reviewed and work on this problem, based on the density functional theory of freezing and replicated liquid state theory, are summarized in this context. A few directions for further work on this problem are suggested.

3 illus, 90 ref