010026   Das N R (NO, , P - 60, Green, View, Kolkata-700 084) : Application of radiations and radioisotopes in imroving the quality of human life. Sci Cult 2007, 73(7-8), 201-12.

Discovery of radioactivity and the subsequent development of the nuclear reactors and accelerators have opened up the floodgate for production of varieties of artificial radioisotopes of different elements and as of today, more than 2500 artificially produced radioisotopes are available. Nuclear scientists and technologists have heralded the peaceful applications of radiations and radioisotopes as powerful tools in diverse fields like medical, industrial, agricultural, environmental and chemical research for the benefit of mankind. The choice of a particular radiation or a radioisotopic source for its beneficial application is always guided by its characteristic nuclear properties, intensity, availability and compatibility with the system under investigation. For example, in health care, high intensity radioactive sources are utilized in teletherapy unit, particularly, for treatment of cancer, and medium level sources are used in brachytherapy and diagnostic purposes. In industry, radiation sources from medium to high level activities are applied for radiation processing, non-destructive testing, nucleonic probes, etc. Utilization of high energy radioisotopic sources or accelerators in medical sterilization, food irradiation and decontamination of waste-waters and sewages are of great commercial importance. Radiation helps in conversion of the gaseous pollutants in fossil fuel emissions from power plants to agricultural fertilizers. Production of more and more artificial radioisotopes for peaceful applications in newer areas is an ongoing process and the present article primarily deals with the beneficial applications of radiations and radioisotopes in some important non-power fields in improving the quality of human life with minimum acceptable risks.

1 table, 6 ref

010025   Bandyopadhyay A (NO, M. P. Birla Institute of Fundamental Research, M. P. Birla Planetarium, Kolkata-700 071) : Why planet pluto dethroned?. Sci Cult 2007, 73(9-10), 289-93.

Twenty sixth general assembly of the International Astronomical Union (IA U) was held in the Czech capital Prague on August 14-25, 2006 and on 24lh August, Pluto was stripped of its status as a planet. Basic reasons for dethroning Pluto are : (i) the eccentricity of Pluto's orbit is the highest-of all planets in the solar system, and as such Pluto has not been able to clear-the neighbourhood around its orbit; (ii) Pluto's orbit is inclined 17 degrees to the plane of the ecliptic, this is very unusual, (Hi) the Common Centre of gravity of our earth and is moon lies below the surface of the earth, whereas the same of Pluto and its satellite Charon lies in space between them - this is another anomaly. Moreover due to the newly invented charge couple device (CCD) camera, a good number of small planets have been discovered in the outer solar system, they are all orbiting around the sun with orbital radii between 30 and 50 A.U. (AU is astronomical unit, which is the average distance of earth from the sun = 149,603,500 km). All these factors forced the IAU to draw a clear distinction between Pluto and the other eight planets.

4 illus, 8 ref

008958   Yadav R P;Gangwar C P;Kumar S (Physics Dep, Govt. P.G. College, Bisalpur (Pilibhit)-262 201, Email: cp16gangwar@rediffmail.com) : Interaction of overtaking disturbances with isothermal strong cylindrical shock in uniform medium. Indian J Theor Phys 2008, 54(3), 177-92.

Effect of overtaking disturbances (EOD) on the propagation of strong diverging cylindrical shock in uniform medium including radiation heat flux has been investigated. Expressions, for flow variables of CCW method modified by overtaking disturbances {Yadav 1992} have been obtained and discussed through figures and tables.]

8 illus, 6 tables, 15 ref

008957   Yadav R K;Mishra V (Physics Dep, D. B. S. College, Kanpur-208 012) : Rate of change of vorticity covariance of dusty fluid turbulence in the presence of magnetic field in a rotating system. Indian J Theor Phys 2008, 54(2), 139-43.

Derived an equation for the rate-of change of vorticity covariance in rotating system. When the motion is referred to axes which rotate steadily with the bulk of the fluid, the corialies and centrifugal force must be supposed to act on the fluid.

8 ref

008956   Yadav R K;Mishra V (Physics Dep, D.B.S. College, Kanpur-208 012) : Distribution functions in the statistical theory of convective MHD turbulence of mixture of a miscible incompressible fluid. Indian J Theor Phys 2008, 54(3), 205-17.

Cosidered the distribution unction of velocity, magnetic, temperature and concentration fields for a heat conducting mixture of a miscible fluid in MHD turbulent state.]

6 ref

008955   Vishwakarma J P;Rai A (Mathematics and Statistics Dep, D.D.U. Gorakhpur Univ, Gorakhpur-273 009) : Propagation of shock waves in a dusty gas with exponentially decreasing density and temperture. Indian J Theor Phys 2008, 54(2), 164-75.

Shock velocity and effective Mach number are obtained for a shock wave propagating in a dusty gas (a mixture of a gas and small solid particles) by use of Whitham's rule. The initial density and temperature of the mixture are assumed to be decreasing exponentially. The results are obtained for different values of the mass concentration of solid particles in the mixture k_p, the ratio of density of solid particles and density of initial gas at the origin G_c and the index of variation of initial temperature<128><108>.

2 illus, 18 ref

008954   Vincent U E;Njah A N;Akinlade O (Physics Dep, Nonlinear and Statistical Physics Research Group, Olabisi Onabanjo Univ, P.M.B. 2002, Ago-Iwoye, Nigeria, Email: ue_vincent@yahoo.com) : Synchronization and basin bifurcations in mutually coupled oscillators. Pramana J Phys 2007, 68(5), 749-56.

Synchronization behaviour of two mutually coupled double-well Duffing oscillators exhibiting cross-well chaos is examined. Synchronization of the subsystems was observed for coupling strength k<62> 0.4. It is found that when the oscillators are operated in the regime for which two attractors coexist in phase space, basin bifurcation sequences occur leading to n + I,n<62> 2 basins as the coupling is varied - a signature of Wada structure and final-state sensitivity. However, in the region of complete synchronization, the basins structure is identical with that of the single oscillators and retains its essential features including fractal basin boundaries.

4 illus, 42 ref

008953   Undre P;Helambe S N;Jagdale S B;Khirade P W; Mehrotra S C (Microwave Research Lab, Physics Dep, Dr. B.A.M. Univ, Aurangabad-431 004, Email: prabhakar222@rediffmail.com) : Microwave dielectric characterization of binary mixture of formamide with N, N-dimethylaminoethanol. Pramana J Phys 2007, 68(5), 851-61.

Dielectric relaxation measurements of formamide (FMD)-N,N - dimethylaminoethanol (DMAE) solvent mixtures have been carried out over the entire concentration range using time domain reflectometry technique at 25, 35 and 45degreC in the frequency range of 10 MHz to 20 GHz. The mixtures exhibit a principle dispersion of the Davidson-Cole relaxation type at microwave frequencies. Bilinear calibration method is used to obtain complex permittivity ε*(w) from complex reflection coefficient p*'w) over the frequency range of 10 MHz to 10 GHz. The excess permittivity (e ), excess inverse relaxation time (l/r)^E, Kirkwood correlation factor (g^eff), activation energy and Bruggeman factor (/B) are also calculated to study the solute-solvent interaction.

6 illus, 3 tables, 34 ref

008952   Turkan N;Maras I (Faculty of Arts and Science, Bozok Univ, 66100 Yozgat, Turkey, Email: nurettin_turkan@yahoo.com) : Microscopic interacting boson model calculations for even-even <. Pramana J Phys 2007, 68(5), 769-78.

Determines the most appropriate Hamiltonian that, is needed for the present calculations of energy levels and B(E2) values of ¹²⁸-138 Ce nuclei which have a mass around A≅ 130 using the interacting boson model (IBM). Using the best-fitted values of parameters in the Hamiltonian of the IBM-2, we have calculated energy levels and B(E1} values for a number of transitions in^{128,130,132,134,136,138} Ce. The results were compared with the previous experimental and theoretical (PTSM model) data and it was observed that they are in good agreement. Also some predictions of this model have better accuracy than those of PTSM model. It has turned out that the interacting boson approximation (IBA) is fairly reliable for calculating spectra in the entire set of ¹²⁸,130,132,134,ise,138 Ce isotopes and the quality of the fits presented in this paper is acceptable.

2 illus, 36 ref

008951   Sushil Kumar;Singh S K;Gwal A K (Physics Div, School of Engineering and Physics, The Univ the South Pacific, Suva, Fiji, Email: kumar_su@usp.ac.fj) : Effect of upflowing field-aligned electron beams on the electron cyclotron waves in the auroral magnetosphere. Pramana J Phys 2007, 68(4), 611-22.

The role of low density upflowing field-aligned electron beams (FEBs) on the growth rate of the electron cyclotron waves at the frequencies we_r <60>μ_e, propagating downward in the direction of the Earth's magnetic field, has been analysed in the auroral region at w_e/μe,<60> 1 where w_e is the plasma frequency and U_e is the gyrofrequency. The FEBs with low to high energy (E_{b>D but with low temperature (Tb) have no effect on these waves. The FEBs with Eb<60><60> keV and Tb (<62>1.5 keV) have been found to have significant effect on the growth rate. Analysis has revealed that it is mainly the T||b which inhibits the growth rate (magnitude) and the range of frequency (bandwidth) of the instability mainly in the higher frequency spectrum. The inhibition in the growth rate and bandwidth increases with increase in T||b. The FEBs with less Eb<62> (giving drift velocity) reduce growth rate more than the beams with larger Eb The inhibition of growth rate increases with the increase in the ratio we/Ξe indicating that the beams are more effective at higher altitudes.}

5 illus, 26 ref

008950   Singh T;Chaubey R (Applied Mathematics Dep, Institute of Technology, Banaras Hindu Univ, Varanasi-221 005, Email: drtrilokisingh@yahoo.co.in) : Bianchi type-V universe with a viscous fluid and Λ-term. Pramana J Phys 2007, 68(5), 721-34.

Studies the evolution of a homogeneous, anisotropic universe given by a Bianchi Type-V cosmological model filled with viscous fluid, in the presence of cos-mological constant A. The role of viscous fluid and A-term in the Bianchi Type-V universe has been studied.

21 ref

008949   Singh C P;Kumar S (Applied Mathematics Dep, Delhi College of Engineering, Bawana Road, Delhi-110 042, Email: cpsphd@rediffmail.com) : Bianchi type-II inflationary models with constant deceleration parameter in general relativity. Pramana J Phys 2007, 68(5), 707-20.

Einstein's field equations are considered for a locally rotationally symmetric Bianchi Type-II space-time in the presence of a massless scalar field with a scalar potential. Exact solutions of scale factors and other physical parameters are obtained by using a special law of variation for Hubble's parameter that yields a constant value of deceleration parameter. To get inflationary solutions, a flat region is considered in which the scalar potential is constant. Power-law and exponential cases are studied and in both solutions there is an anisotropic expansion of the cosmic fluid, but the fluid has vanishing vorticity. A detailed study of geometrical and kinematical properties of solutions has been carried out.

33 ref

008948   Sharma H;Prakash S (Applied Science Dep, Rayat and Bhara Institute of Engineering and Bio-Technology, Sahauran, Mohali-140 104, Email: hitesh@rbiebt.ac.in) : Atomic displacements in bcc dilute alloys. Pramana J Phys 2007, 68(4), 655-77.

Present a systematic investigation of the atomic displacements in bcc. transition metal (TM) (mute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method. Wills and Harrison interatomic potential is used to calculate the atomic force constants, the dynamical matrix and the impurity-induced forces. We have thoroughly investigated the atomic displacements using impurities from 3d, 4d and 5d series in the same host metal and the same impurity in different hosts observes a systematic pattern in the atomic displacements for Cr-, Fe-, Nb-, Mo-, Ta- -tmd W-based dilute alloys. The atomic displacements are found to increase with increase in the number of d electrons for all alloys considered except for V dilute alloys. The 3d impurities are found to be more easily dissolved in the 3d host metals than 4d or 5d TMs whereas 4d and 5d impurities show more solubility in 4d and 5d TMs. In general, the relaxation energy calculation suggests that impurities may be easily solvable in 5d TM hosts when compared to 3d or 4d TMs.

7 illus, 2 tables, 17 ref

008947   Sanyal D C;Adhikari A (Mathematics Dep, Kalyani Univ, Kalyani-741 235) : Unsteady free convection MHD flow between two heated vertical parallel conducting plates. Indian J Theor Phys 2008, 54(3), 219-35.

Unsteady free convection flow of a viscous incompressible electrically conducting fluid between two heated conducting vertical parallel plates subjected to a uniform transverse magnetic field is considered. The approximate analytical solutions for velocity, induced field and temperature distribution are obtained for small and large values of magnetic Reynolds number. The problem is also extended to thermometric case.]

12 illus, 10 ref

008946   Roy S K;Jha L (Physics University Dep, L. N. Mithila Univ, Darbhanga-846 004) : Study of the design of broad and single layer microstrip patch antenna. Indian J Theor Phys 2008, 54(2), 107-16.

A simple new design of wide band single layer co-axially fed -rectangular microstrip patch antenna has been obtained by cutting a U-shaped slot on the patch. Two parallel slots are incorporated into the patch of a microstrip antenna to expand its bandwidth. This paper develops principle design procedures through examnation of the tructure's multiple resonant frequencies as well as the radiation and impedance properties of different antenna geometries. Simulations and measurements of several antennas design using these new rules are presented. Theoretical and experimental results agree very well.]

4 illus, 2 tables, 6 ref

008945   Rema Devi B S;Raveendran R;Vaidyan A V (Crystal Growth Laboratory, Physics Dep, S.N. College, Kollam-691 001, Email: remadevi1956@rediffmail.com) : Synthesis and characterization of Mn<. Pramana J Phys 2007, 68(4), 679-87.

Mn²⁺-doped ZnS nanoparticles were prepared by chemical arrested precipitation method. The samples were heated at 300, 500, 700 and 900degreeC. The average particle size was determined from the X-ray line broadening. Samples were characterized by XRD, FTIR and UV. The composition was verified by EDAX spectrum. The hexagonal structure of the sample was identified. The size of the particles increased as the annealing temper-, ature was increased. The crystallite size varied from 5 nm to 34 nm as the calcination temperature increased. At around 700degreeC, ZnS is converted into ZnO phase due to oxidation. The emission peak of the sample is observed at 300 nm resulting in blue emission. The solid state theory based on the delocalized electron and hole within the confined volume can explain the blue-shifted optical absorption spectra. UV-VIS spectro-photometric measurement shows an indirect allowed band gap of 3.65 eV.

5 illus, 4 tables, 15 ref

008944   Raychaudhuri P (Applied Mathematics Dep, Calcutta Univ, 92, Acharya Prafulla Chandra Road, Kolkata-700 009) : Total solar irradiance variation and the solar activity cycle. Indian J Theor Phys 2008, 54(2), 97-106.

It is shown that multiple periods of the total solar irradiance data within the solar activity cycle indicates that there are multiple phases e.g., five phases in the solar activity cycle as in the sunspot numbers data, solar magnetic data, solar neutrino flux data, solar proton data, etc. Suggests that all the phases are different from one another indicating the different physical conditions on the surface (temperature, magnetic fields, active network components etc.) during the solar activity cycle. ]

1 illus, 37 ref

008943   Ramanathan R;Gupta K K;Jha A K;Singh S S (Physics Dep, Delhi Univ, Delhi-110 007, Email: drramanathan@vsnl.net) : Interfacial surface tension of a quark-gluon plasma fireball in a hadronic medium. Pramana J Phys 2007, 68(5), 757-68.

Calculate the interfacial surface tension of a QGP-fireball in a hadronic medium in the'Ramananian et al statistical model. The constancy of the ratio of the surface tension with the cube of the critical transition temperature is in overall accordance with lattice QCD findings. It is in complete agreement with a recent MIT bag model calculation of surface tension. The velocity of sound in the QGP droplet is predicted to be in the range (0.27 ñ 0.02) times the velocity of light in vacuum and this value is independent of both the value of the transition temperature and the model parameters.

8 illus, 2 tables, 16 ref

008942   Ram Gopal;Deepak V;Sivaramakrishnan S (Physics Dep, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam-515 134, Email: srk.phy.psn@sssihl.edu.in) : Systematic study of spatiotemporal dynamics of intense femtosecond laser pulses in BK-7 glass. Pramana J Phys 2007, 68(4), 547-69.

Presents a systematic study of the spatial and temporal effects of intense femtosecond laser pulses in BK-7 over a broad range of input powers, 1-1000 times the critical power for self-focusing (Per) by numerically solving the nonlinear Schrodinger equation (NLS). Most numerical studies have not been extended to such high powers. A clear-cut classification of spatio-temporal dynamics up to very high powers into three regimes - the group-velocity dispersion (GVD) regime, the ionization regime and the dominant plasma regime - as done here, is a significant step towards a better understanding. Further, Auhor examine in detail the role of GVD in channel formation by comparing BK-7 to an 'artificial' medium. Our investigations bring forth the important observation that diffraction plays a minimal role in the formation of multiple cones and that plasma plays a diffraction-like role at very high powers. A detailed study of the spatio-temporal dynamics in any condensed medium over this range of powers has not been reported hitherto, to the best of our knowledge. Also suggests appropriate operational powers for various applications employing BK-7 on the basis of our results.

10 illus, 66 ref

008941   Raj Kumar;Mohan D;Kaura S K;Chhachhia D P; Aggarwal A K (Coherent Optics Div, Central Scientific Instruments of Organisation, Sector 30, Chandigarh-160 030, Email: aka1945@rediffmail.com) : Phase knife-edge laser Schlieren diffraction interferometry with boundary diffraction wave theory. Pramana J Phys 2007, 68(4), 581-9.

Within the framework of boundary diffraction wave theory it has been shown that the bright fringe on either side of the central dark fringe of the phase knife-edge Fresnel diffraction pattern could be broadened to cover the whole field of view. Broadening of the first diffraction fringe, instead of conventionally modifying the spatial frequency spectrum, enhances the sensitivity of the Schlieren system. The use of phase knife-edge as viewing diaphragm in Schlieren diffraction interferometry not only enhances the fringe contrast but also avoids the loss in phase information as it lets through light from all parts of the test object and its thin interfacing makes the method suitable even for studying weak disturbances.

4 illus, 24 ref

008940   Madan Jee;Pandey S B;Veena Kumari;Rakhi (University Physics Dep, B.R.A. Bihar University, Muzaffarpur, Bihar) : Effect of external magnetic field on wigner molecule. Bull pure appl Sci-Sect D 2007, 26(1), 25-8.

Studies the phase transitions in Wigner molecules induced by an external magnetic field. The symmetry of the Wigner molecule phase that emerges from the maximum density droplet phase, is different from the classically obtained values. The existence of several phases of wigner molecule with different symmetries should be observed in the magnetic field above the maximum density droplet breakdown transition.

2 illus, 6 ref

008939   Madan Jee;Pandey S B;Ajoy;Sanjiv Kumar;Sanjiv Kumar (University Physics Dep, B.R.A. Bihar University, Muzaffarpur, Bihar) : Electron-phonon coupling in resonant scattering of carriers by an external potential. Bull pure appl Sci-Sect D 2007, 26(1), 49-52.

Role of the coupling of electrons to longitudinal optical phonons in polar semiconductors on formation of long range bound states and this coupling leads to the formation of bound states in weaker potentials. The effect of the coupling to acoustic phonons is reduced to the renormalization of the carrier effective mass. In the III-V semiconductors the effect of the binding of electrons by fluctuations of the dopant concentration is expected, the interactions with acoustic phonons is small.

2 illus, 15 ref

008938   Lo C Y (NO, Applied and Pure Research Institute, 17 Newcastle Drive, Nashua, NH 03060 USA) : Necessity of unifying gravitation and electromagnetism, mass-charge repulsive effects, and the five dimensional theory. Bull pure appl Sci-Sect D 2007, 26(1), 29-52.

It is found that the Reissner-Nordstrom metric enables to show that general relativity + electrodynamics are not yet a close system. Due to the electromagnetic energy, there is a repulsive effect in gravity. Analysis of this effect shows that the geodesic equation as the equation of motion is inadequate. To include the force of charge-mass repulsion, modifications of electromagnetic and gravitational theories are necessary. Moreover, it is shown that the unification within the theoretical framework of a five-dimensional theory would resolve this problem because of the additional metric elements. In the five-dimensional theory of Einstein and Pauli, those elements were disregarded as having no physical meaning. Concurrently, a limitation of the formula E = mc² is proven and experimental verifications of the new force are discussed. Thus, the full meaning of relativity is still emerging after 100 years of Einstein's creation.

55 ref

008937   Korunur M;Salti M;Havare A (Physics Dep, Dicle Univ, 21280, Diyarbakir-Turkey, Email: mkorunur@dicle.edu.tr) : On the relative energy associated with space-times of diagonal metrics. Pramana J Phys 2007, 68(5), 735-48.

In order to evaluate the energy distribution (due to matter and fields including gravitation) associated with a space-time model of generalized diagonal metric,consides the Einstein, Bergmann-Thomson and Landau-Lifshitz energy and/or momentum definitions both in Einstein's theory-of general relativity and the teleparallel gravity (the tetrad theory of gravitation). find same energy distribution using Einstein and Bergmann-Thomson formulations, but we also find that the energy-momentum prescription of Landau-Lifshitz disagree in general with these definitions, Also givepeight different well-known space-time models as examples, and considering these models and using our results, we calculate the energy distributions associated with them. Furthermore, we show that for the Bianchi Type-I models all the formulations give the same result. This result agrees with the previous works of Cooperstock-Israelit, Rosen, Johri et al, Banerjee-Sen, Xulu, Vargas and Salti et pl and supports the viewpoints of Albrow and Tryon.

48 ref

008936   Kholiya K;Gupta B R K (Physics Dep, G.B. Pant Univ Agriculture and Technology, Pantnagar-263 145, Email: brkg@rediffmail.com) : Structural phase transition and elastic properties of thorium pnictides at high pressure. Pramana J Phys 2007, 68(4), 649-54.

Pointes out the weaknesses of the approach by Aynyas et al [I] to study the structural phase transition and elastic properties of thorium pnictides. The calculated values of phase transition pressure and other elastic properties using the realistic and actual approach are also given and compared with the experimental and previous theoretical work.

3 tables, 19 ref

008935   Kharab R;Ravinder Kumar;Pardeep Singh;Sharma H C (Physics Dep, Kurukshetra Univ, Kurukshetra-136 119, Email: kharabrajesh@rediffmail.com) : One-neutron stripping reactions of <. Pramana J Phys 2007, 68(5), 779-87.

Calculates the one-neutron absorption cross-section and the longitudinal momentum distribution of the core fragment coming out from the breakup of ¹¹Be and ¹⁹C on ⁹Be target at 63 MeV/A and 88 MeV/A beam energies respectively. The reaction mechanism is treated within the framework of the eikonal approximation. The effective range of the nuclear interaction between the core and the valence neutron within the projectile has been determined by comparing the predicted stripping cross-section with the recently measured one. The effective range for ¹⁹C has been found to be smaller than that for ¹¹Be. It qualitatively indicates that ¹⁹C is slightly more halo than ¹¹Be. The smaller width, predicted as well as measured, of the LMD of ¹⁸C than ¹⁰Be also strengthens this fact. The experimental data concerning the LMD of core fragments have been well represented.

3 illus, 1 table, 17 ref

008934   Karya S;Sharma A K;Agarwala R A (NO, Guru Jambheshwar Univ, Hisar-125 001) : BER estimation for optical communication system using variety for fibers in the presence of dispersion and fiber non-linearities. IETE J Res 2007, 53(4), 355-63.

In this paper, optical transmission system at 10Gb/s using NRZ source has been simulated with commercial package OptSim. The Bit Error Rate (BER) for optical transmission system using a variety of available fibers near reference loss wavelength of 1550 nm in the presence of chromatic dispersion and fiber nonlinearities has been estimated up to 300 kms. Results have been obtained by considering the impact of second and third order dispersion terms. It has been investigated that the highest repeaterless distance without dispersion compensation for DS_ Anomalous fiber is 246 kms at BER 10^-10.

2 illus, 2 tables, 6 ref

008933   Karmakar P K (Physics Dep, Tezpur Univ, Napaam, Tezpur-784 028, Email: pkk@tezu.ernet.in) : Application of inertia-induced excitation theory for nonlinear acoustic modes in colloidal plasma equilibrium flow. Pramana J Phys 2007, 68(4), 631-48.

Application of inertia-induced acoustic excitation theory offers a new resonant excitation source channel of acoustic turbulence in the transonic domain of plasma flow. In bi-ion plasmas like colloidal plasma, two well-defined transonic points exist corresponding to the parent ion and the dust grain-associated acoustic modes. As usual, the modified ion acoustic mode (also known as dust ion-acoustic (DIA) wave) dynamics associated with parent ion inertia is excitable for both nanoscale- and micronscale-sized dust grains. It is found that the so-called (ion) acoustic mode (also known as dust-acoustic (DA) wave) associated with nanoscale dust grain inertia is indeed resonantly excitable through the active role of weak but finite parent ion inertia. It is interestingly conjectured that the same excitation physics, as in the case of normal plasma sound mode, operates through the active inertial role of plasma thermal species. Details of the nonlinear acoustic mode analyses of current interest in transonic domains of such impure plasmas in hydrodynamic flow are presented.

28 ref

008932   Kalyanaraman S B;Jayakumari T;Arulmozhi K T (Physics Wing (DDE), Annamalai University, Annamalainagar-608 002, Email: kau2004sify.com) : Evaluation of suitability of various theories in the prediction of ultrasonic velocities in binary liquid systems. Bull pure appl Sci-Sect D 2007, 26(1), 43-7.

Several theories, relations and empirical approaches exist to predict the velocity of ultrasonic waves in multicomponent liquid mixtures. All these have certain inherent defects in that they are well suited to the study of particular type of liquid systems. An attempt has been made to evaluate the suitability of these theories in their prediction capability.

4 tables, 9 ref

008931   Kalanov T Z (NO, Home of Physical Problems, Pisatelskaya 6a, 700200 Tashkent, Uzbekistan, Email: tzk_uz@yahoo.com) : Critical analysis of the special theory of realtivity. Bull pure appl Sci-Sect D 2007, 26(1), 1-15.

Critical analysis of the generally accepted foundations of the special theory of relativity is proposed. The principle of the unity of formal logic and dialectics is a methodological basis of the analysis. The result is as follows: the foundations (i.e., the interpretation of Michelson-Morley's experimental data and calculations, the contraction hypothesis and the Lorentz transformation formulae, concept of space-time, Einstein's formula expressing equivalence of mass and energy) contain logical errors and are not consequence of any postulates. The existence of logical errors is irrefutable proof of incorrectness of the special theory of relativity. The following correct theories and principles are proposed: theory of time; theory of space; the quantum theory of constancy of light speed; the principle of equivalency of mass and energy; the principle of objectivity of human knowledge; the theory of system of reference.

31 ref

008930   Kailash;Raju K M (Physics Dep, Brahmanand P. G. College, Rath, Hamirpur-210 431) : Theoretical evaluation of higher order elastic constants and pressure derivatives of some magnesium compounds. Indian J Theor Phys 2008, 54(3), 237-48.

A theory has been evolved for obtaining the second, third and fourth-order elastic constants at any temperature starting from nearest neighbour distance and hardness parameter assuming Coulomb and Born Mayer potentials for face centered cubic crystals. Elastic energy density for a deformed crystal is expanded as a power series of strains using Taylor's series method. Several expressions for the second, third and fourth order elastic constants are obtained at OK and elevated temperature and the results are tabulated. The anharmonicities of MgO, MgSe and MgS are also obtained using these constants. A comparison between present and experimental results is also made wherever possible.]

10 tables, 32 ref

008929   Kadam R H;Alone S T;Bichile G K;Jadhav K M (Physics Dep, Dr. Babasaheb Ambedkar Marathwada Univ, Aurangabad-431 0014, Email: drstalone@yahoo.co.in) : Measurement of atomic number and mass attenuation coefficient in magnesium ferrite. Pramana J Phys 2007, 68(5), 869-74.

Pure magnesium ferrite sample was prepared by standard ceramic technique and characterized by X-ray diffraction method. XRD pattern revealed that the sample possess single-phase cubic spinel structure. The linear attenuation coefficient (μ), mass attenuation coefficient (μ/P), total atomic cross-section (σ_tot), total electronic cross-section (σ_ele) and the effective atomic number (Z_eff) were calculated for pure magnesium ferrite (MgFfe₂O₄). The values of 7-ray mass attenuation coefficient were obtained using a Nal energy selective scintillation counter with radioactive 7-ray sources having energy 0.36, 0.511, 0.662, 1.17 and 1.28 MeV. The experimentally obtained values of μ/p and Z_eff agreed fairly well with those obtained theoretically.

2 illus, 2 tables, 21 ref

008928   Joshi P;Sharma R K;Jai Kishore;Kher S (Fibre Optics Lab, Solid State Laser Div, Raja Ramanna Centre for Advanced Technology, Indore-452 013, Email: kher@cat.ernet.in) : Fabrication of photonic crystal fibre. Curr Sci 2007, 93(9), 1214-15.

4 illus, 6 ref

008927   Jha S S;Mahanti S D (Physics Dep, Indian Institute of Technology Bombay, Mumbai-400 076, Email: ssjha@phy.iitb.ac.in) : Hartree-fock variational bounds for ground state energy of chargeless fermions with finite magnetic moment in the presence of a hard core potential: a stable ferromagnetic state. Pramana J Phys 2007, 68(5), 819-30.

Authors uses different determinantal Hartree-Fock (HF) wave functions to calculate true variational upper bounds for the ground state energy of N spin-half fermions in volume V₀, with mass m, electric charge zero and magnetic moment μ, interacting through magnetic dipole-dipole interaction. Authors find that at high densities when the average inter-particle distance r₀ becomes small compared to the magnetic length r_m ≡ 2mμ²/h², a ferromagnetic state with spheroidal occupation function n↑(k), involving quadrupolar deformation, gives a lower upper bound compared to the variational energy for the uniform paramagnetic state or for the state with dipolar deformation. This system is unstable towards infinite density collapse, but we show explicitly that a suitable short-range repulsive (hard core) interaction of strength U_o and range a can stop this collapse. The existence of a stable equilibrium high density ferromagnetic state with spheroidal occupation function is possible as long as the ratio of coupling constants Γ_cm ↑ (U₀a³/μ²) is not very small compared to 1.

2 illus, 6 ref