bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave Absorption in Compressed Carbon Monoxide and Nitrous Oxide
Authors: Andrews JC
Published: June 2013

The absorption of microwaves by both CO and N2O has been measured at a frequency of 9�75 GHz using a resonant cavity technique. The power absorption coefficients were measured at pressures up to 670 bars for CO at 20�5�C, 54 bars for 20 at 25�C, and 121 bars for N2O at 40�C. In all cases the power absorption coefficient was found to increase with density up to the highest pressures reached. The theory of Van Vleck and Weisskopf fails to account for the measured absorption except at low densities. At higher densities the measured absorption was in excess of that predicted by this theory and the discrepancy increased with increasing density. The theory of Ben-Reuven accounts for the absorption up to intermediate densities but at high densities it also predicts values which are smaller than the measured ones. However, it is possible to account for the measured absorption by considering it to be the sum of a resonant contribution, which is assumed to be given by the Van Vleck-Weisskopf theory, and a nonresonant collision-induced contribution which increases with density and is assumed to be the result of collisions so strong that rotation of the molecules is quenched.
On the Non-invariance of Distributions of Reaction Matrix Parameters Under Changes in Boundary Conditions
Authors: Bertram WK , Cook JL
Published: June 2013

Contrary to current opinion, the statistical distributions of level spacings and reduced widths when applied to the reaction matrix are not invariant under changes in the boundary condition matrix or the matching radius. General arguments are given, together with specific examples which violate the invariance requirements. We conclude that it may be the parameters of the collision matrix which should be analysed and considered as the invariant parameters. It is shown that if, for a specific set of boundary conditions, the distributions of level spacings and reduced widths are uncorrelated, then correlations between the level spacings and widths must exist when different boundary conditions are used.
Improved Positions and Some Identifications for 108 Radio Sources Between Declinations ?33° and +27°
Authors: K Merkelijn Jeannette
Published: June 2013

Positions of improved accuracy have been obtained for 108 sources from the Parkes catalogue between declinations ?33� and +27�. The estimated errors in the positions are less than 15" arc in both coordinates. Identifications are suggested for 17 sources, 12 with possible quasi-stellar objects and 5 with galaxies.
General Relativity in the Equal Proper Time Formalism
Authors: Cook JL
Published: June 2013

The general theory of relativity is discussed within the framework of the concept of surfaces of equal proper time as outlined in a previous paper. The three main tests of general relativity, namely the precession of the perihelion of Mercury, the gravitational shift of spectral lines, and the gravitational deflection of light rays by massive sources, are considered and it is shown that, though the modified equations are Lorentz-invariant with respect to distant observers, the deviations from conventional results are so minute as to be undetectable.
Effect of Rapidly Rising Proton?Proton Total Cross Sections on Idealized Extensive Air Showers
Authors: Campbell JA
Published: June 2013

A simulation of extensive air showers above 1013 eV in which proton?proton scattering takes place partly through a medium-strong interaction is reported. In previous papers the simulation has been shown to be in fair agreement with observational data. The present version includes for the first time the assumption that the total cross section for proton-proton scattering increases with energy, as concluded in a recent paper by Yodh, Pal, and Trefil. The effect of the assumption is to make a noticeably better agreement between the simulation and the data.
Neutron Resonance Spectroscopy on 209Bi
Authors: de L Musgrove AR , Harvey JA
Published: June 2013

The neutron transmission through 209Bi was measured with high resolution at both the 80 and 200 m stations of the Oak Ridge Electron Linear Accelerator. Resonance parameters for s-wave levels below 270 keY and for p-wave levels below 100 keY bombarding energy were obtained. Approximately 25 % of the expected neutron strength of a particle-vibrator doorway was identified in the energy range analysed for s-wave resonances. The average s-wave level spacing is s = 4�5 � 0�6 ke V after correcting for missed levels. The s- and p-wave neutron strength functions are respectively: 104 So = 0�65 � 0�15 (E < 170 keY); 104 Sl = o� 25 � 0�07 (E < 60 keY). Both strength functions show evidence of energy-dependent structure.
Phase Equivalent Potentials in Reaction Matrix Theory
Authors: Lang DW , Cook JL
Published: June 2013

The general class of phase equivalent nonlocal potentials is examined using standard reaction matrix methods. The relationship between phase equivalent overlap matrices is derived and it is found that the matrices fall into four general classes.
Variations in the Ultrasonic Velocity within Electrolytic Solutions Under Ionic Drift
Authors: Agarwal SB , Bhatnagar VP
Published: June 2013

Measurements are presented which show that the ultrasonic velocity v in aqueous solutions of common electrolytes increases with the ionic drift current density j, such that dv ex: exp(j!).
Widths of the 14·32 and 14·40 MeV Levels in 160
Authors: Clark PD , Johnston A , Ophel TR
Published: June 2013

By means of measurements of the 14N(tx, d) reaction, the widths of the 14�32 and 14�40 MeV levels in 160 have been determined to be 34� 12 and 27 � 5 keV respectively. No evidence was found for resonances corresponding to these levels in the 15N(p, (XjI) reaction.
Perturbed Characteristic Functions: Application to the Linearized Gravitational Field
Authors: Buchdahl HA
Published: June 2013

The first-order perturbation induced by the first-order perturbation of a given Lagrangian in its associated characteristic function V is given by a simple integral along the unperturbed extremals. This result is applied to the world characteristic of the linearized gravitational field. Various specialized situations are considered. For example, to obtain V(1) in the quasi-Newtonian approximation one merely needs to evaluate a three-dimensional volume integral over the product of the energy density and a type of two-point Green's function.
Effects of the Wavenumber Spectrum of a Sea Surface on Laser Beam Reflection
Authors: Phillips DM
Published: June 2013

The angular and temporal distributions of energy in the reflection of a pulsed laser beam from a sea surface depend on the diameter of the beam and on the wavenumber spectrum of the water surface. Theoretical expressions are derived for the influence on the reflection of the mean height and slope of waves in the illuminated area as well as the variation of the height and slope within this area. The results are applied to airborne lasers for wave height profiling, altimetry and water depth sounding. The optimum beam diameter depends on both the application and the wavenumber pectrum of the water surface.
Analysis of the (p,2p) Reaction in an Asymmetric Energy-sharing Mode
Authors: Smith R , Morrison I , Amos K
Published: June 2013

A half distorted-wave formalism, applicable specifically to the analysis of the (p,2p) reaction in an asymmetric energy-sharing mode, is developed. The formalism explicitly includes t-matrix operators of central and tensor forms, and the expansion of the technique to include an intermediate giant resonance excitation mechanism is discussed. Application is made to analyses of the 12C(p,2p) reaction in both symmetric and asymmetric energy-sharing geometries and, when semi-phenomenological effective interaction forms of the type in current use in the analysis of (p, p') data are used, it is shown that the spectroscopic information extracted from the analysis of the asymmetric mode (p,2p) data is in good agreement with the predictions of Op shell model calculations.
An Interpretation of the Blue Satellite to Resonance Lines of Helium-like Ions of Third Sequence Elements in Laser-produced Plasmas
Authors: Irons FE
Published: June 2013

It is suggested that the blue satellite to resonance lines of helium-like ions of third sequence elements, observed in laser-produced plasmas by Boiko et at. (1974, 1975) and others and tentatively identified as a Baranger-Mozer satellite, is in fact the blue peak of the self-reversed resonance line profile which has been rendered asymmetrical (red peak enhanced and blue peak suppressed) by differential plasma motion. The various properties reported for the blue satellite are shown to be consistent with model calculations and with the known properties of optically thick, velocity-affected, resonance line profiles of second sequence elements in laser-produced plasmas. The tendency of the satellite to appear preferentially with conical accumulation is explained in terms of the smaller transverse velocities associated with accumulation. One implication of the present interpretation is that, with plane targets, the appearance of an asymmetrically self-reversed line as only a red peak may be the norm rather than the exception; with the further implication that plasma diagnostics based on the misidentification of the red peak as the line proper may be seriously in error.
Nonlinear Double-diffusive Convection in a Low Prandtl Number Fluid
Authors: Riahi N
Published: June 2013

Nonlinear double-diffusive convection is studied using the modal equations of cellular convection. The boundary layer method is used by assuming a large Rayleigh number R for a fluid of low Prandtl number (J, and different ranges of the diffusivity ratio 7: and. the solute Rayleigh number Rs. The heat and solute fluxes are found to increase with R(J and decrease with Rs. The effect of the solute is stabilizing, although the convection in a fluid with large (J is less affected by the solute concentration. The flow is shown to have a solute layer which thickens as (J, R, .-1 or R;l decreases. It is proved that it is only for this layer that the solute affects the boundary layer structure.
Photoacoustic Measurements on Semiconducting Powder Samples
Authors: Wong KY
Published: June 2013

Photoacoustic measurements of several semiconducting powder samples have been performed, and the measured band-gap energies obtained are found to be in good agreement with published values. The advantages of the photoacoustic technique are briefly discussed.
Galactic Plane H2O Masers: A Southern Survey
Authors: Batchelor RA , Caswell JL , Goss WM , Haynes RF , Knowles SH , Wellington KJ
Published: June 2013

An extensive 22 GHz survey of H20 masers has been made with the Parkes 64 m radio telescope. We present data here for 68 sources, of which almost one-half were discovered in the present series of observations. The telescope beamsize, 100' arc to half-power, has enabled us to improve the position measurements of most of the known sources and in a few cases has allowed us to resolve a 'source' into several spatially separated components. The wide velocity coverage of our observations (> 200 km s -1) has led to the discovery of several interesting new high-velocity features. In addition to details for each source, the general properties of the sample are discussed. In the typical interval of 8 months between successive observations, the peak intensity of many sources varied only slightly (by less than a factor of 2); a few sources, however, showed more dramatic variations.
Finite Ligand Size and the Sternheimer Antishielding Factor ?8
Authors: Ahmad S , Newman DJ
Published: June 2013

Two distinct processes, one classical and the other quantum mechanical, have to be considered in allowing for the effect of the finite size of atoms on the shielding of the coupling between crystal and nuclear electric quadrupole moments. The effect of the quantum mechanical process has already been calculated; in this paper we employ a simple numerical technique for evaluating multicentre integrals to calculate the effect of charge penetration. This effect is found to be significant and it suggests that a new approach is necessary in the parameterization of the crystal-nuclear-quadrupole interaction.
Kinetic Theory of Charged Particle Swarms in Neutral Gases
Authors: Kumar Kailash , Skullerud HR , Robson RE
Published: June 2013

The kinetic theory of charged test particles in a neutral gas, in the presence of static and uniform electric and magnetic fields, is reviewed. The effects of inelastic processes and reactions are included. The general space-time development of the swarms is considered and the relation between the nonhydrodynamic anQ hydrodynamic developments is pointed out. The transport coefficients are identified as statistical averages over the configuration-space and phase-space distributions. The evaluation of these averages by computer simulations is briefly discussed.
Matrix Elements of the Boltzmann Collision Operator in a Basis Determined by an Anisotropic Maxwellian Weight Function including Drift
Authors: Kumar Kailash
Published: June 2013

The matrix elements of the linear Boltzmann collision operator are calculated in a Burnett-function basis determined by a weight function which itself describes a velocity distribution with a net drift and an anisotropic pressure (or temperature) tensor. Three different methods of calculation are described, leading to three different types of formulae. Two of these involve infinite summations, while the third involves only finite sums, but at the cost of greater complications in the summands and the integrals over cross sections. Both elastic and inelastic collisions are treated. Special cases arising from particular choices of the parameters in the weight functions are pointed out. The structure of the formulae is illustrated by means of diagrams. The work is a contribution towards establishing efficient methods of calculation based upon a better understanding of the matrix elements in such bases.
A Two-accelerator Facility and Its Use for Radiation Damage Studies in Alkali Halides
Authors: Newton CS , Hay HJ
Published: June 2013

An experimental system is described in which heavy ions of energies 50-100 MeV, and light ions of energies 0�5-2 MeV, may be transported alternatively from different accelerators into a common scattering chamber. Details are given of the beam transport and ~ttering chamber, the latter being designed to make in-beam studies of different modes of radiation damage in the target material. An on-line experimental control and data acquisition system with an IBM 1800 computer is used. Experimental studies are described of simultaneous detection of backscattered helium ions, X-rays and optical absorption in single-crystal alkali halide samples, performed during continuous irradiation by a 1 MeV helium beam, as well as of backscattered protons following intermittent irradiation by a 60 MeV oxygen beam. Analysis of the relative damage by these two beams is discussed in relation to a damage mechanism due to Pooley.
Survey of OH Masers at 1665 and 1667 MHz. I. Galactic Longitudes 326° to 40°
Authors: Caswell JL , Haynes RF , Goss WM
Published: June 2013

The galactic plane between longitudes 3260 and 3400 has been searched for OH emiSSIOn and bsorption on the 1665 and 1667 MHz transitions. Forty main-line emission sources were detected (27 new ones, 13 previously known), and these constitute a sample complete to a weIl-defined lower intensity limit in this region of sky. Line profiles of all sources are shown and the statistics on variability and on the intensity ratios of the ground state transitions are summarized. The completeness of the sample encouraged us to make a first attempt to construct a luminosity function and to estimate the total number of such masers in our Galaxy. A study of the velocity structures showed these to be extremely varied, but none exceed a total range of 25 km s -1; combined velocity and polarization data are compatible with a Zeeman splitting origin for the circular polarization, and with this interpretation several sources yield an estimate for the line-of-sight magnetic field strength of a few mG. Preliminary investigations of the associations with other celestial objects indicate that many of the masers are loosely associated with HII region complexes, but in at least eight instances no HII regions have yet been detected; of these eight masers, two may be associated with supernova remnants and one with an unidentified nonthermal radio source.
Charged Particle Photoemission from 42Ca
Authors: Pywell RE , Thompson MN , Shoda K , Sugawara M , Saito T , Tsubota H , Miyase H , Uegaki J , Tamae T , Ohashi H , Urano T
Published: June 2013

Experimental results are presented for the cross sections measured at 90� of the reactions 42Ca(y, p), 42Ca(y, Po) and 42Ca(y, 1(0) between excitation energies 16 and 28 MeV.
Temperature Dependence of the Diffusion Coefficient for Thermal Electrons in Carbon Dioxide over the Range 296 - 468 K
Authors: Hegerberg R , Elford MT , Crompton RW
Published: June 2013

Values of μN for thermal electrons in carbon dioxide have been derived from measurements of the diffusion coefficient over the temperature range 296–468 K. The present values of μNth are in agreement with those reported by Haddad and Elford.
The Effects of Preionization Level on a ?Stabilized? Z-pinch
Authors: Silawatshananai C , Anderson FSB , Brennan MH , Durance G , Jones IR , Murray EL , Tendys J
Published: June 2013

The influence of the degree of preionization on the formation and properties of a conventional 'stabilized' Z-pinch has been studied experimentally for preionization levels ranging from 2 % to 35 %. It is concluded that there exists the possibility of using varying levels of preionization to tailor radial profiles of density and pressure, and hence to influence the value of Po.
Order?Disorder Transformations in Alloys. The Inclusion of Non-nearest Neighbour Interactions in Cluster Variation Methods. II. Low Temperature Specific Heats for Body Centred Cubic Lattices
Authors: M Hanley Joan , E Peacock Thomas
Published: June 2013

In Part I, the Sanchez and de Fontaine formulation of the cluster variation method was used to study the dependence of the critical temperature and the high temperature specific heat on the ratio of second neighbour to nearest neighbour interaction energy. This method can be extended to find solutions for the ordered state. The dependence of the low temperature specific heat on the interaction energy ratio is studied. As with the critical temperature and high T specific heat studies, it is found that both the sign and magnitude of ex affect the low temperature specific heat.
Sub-rotation and Super-rotation in Pulsar Magnetospheres
Authors: Burman RR
Published: June 2013

For magnetospheric species that are nonrelativistic at the stellar surface in the general oblique rotator model, it is shown that a ondissipative flow branch which is sub-rotating when near the star remains sub-rotating everywhere, but that one which is super-rotating when near the star can become sub-rotating inside the light cylinder. Hence, both flow branches can cross the light cylinder and remain valid outside it.
The Equilibrium Statistical Mechanics of Self-gravitating Systems
Authors: Cally PS
Published: June 2013

The partition function and one- and two-particle distribution functions are calculated fora spherically
symmetric self-gravitating system using a method which is exact except for terms of relative order
N -1. The results are in agreement with those found in the continuum approximation. First approximations
to the correction terms are evaluated with particular emphasis on the form of the pair
distribution as compared with the product of two one-particle distributions.
Mathematical Theory of Cylindrical Isothermal Blast Waves in a Magnetic Field
Authors: Lerche I
Published: June 2013

An investigation is made of the self-similar flow behind a cylindrical blast wave from a line explosion (situated on r = 0, using conventional cylindrical coordinates r, 4>, z) in a medium whose density and magnetic field both vary as r -w ahead of the blast front, with the assumption that the flow is isothermal. The magnetic field can have components in both the azimuthal B(jJ and longitudinal B, directions. It is found that: (i) For B(jJ =f:. 0 =f:. B, a continuous single-valued solution with a velocity field representing outflow of material away from the line of explosion does not exist for OJ OJ > 0 the governing equation possesses a set of movable critical points. In this case it is shown that the fluid flow velocity is bracketed between two curves and that the asymptotes of the velocity curve on the shock are intersected by, or are tangent to, the two curves. Thus a solution always exists in the physical domain r ~ o. The overall conclusion from the investigation is that the behaviour of isothermal blast waves in the presence of an ambient magnetic field differs substantially from the behaviour calculated for no magnetic field. These results have an impact upon previous applications of the theory of self-similar flows to evolving supernova remnants without allowance for the dynamical influence of magnetic pressure and magnetic tension.
Positions and Flux Densities at 5000 MHz for 1133 Weak Radio Sources
Authors: Binette Luc , Carignan Claude , Bolton JG , E Wright Alan
Published: June 2013

Flux densities and positions have been measured at 5000 MHz for all the radio sources in the Parkes 2700 MHz catalogue with S2700 = 0�25 Jy for which no 5000 MHz data have previously been published. The new positions of the sources, which are of considerably higher accuracy than those measured at 2700 MHz, have been examined on the available sky survey material: 17 previously suggested identifications are rejected, but alternative identifications are proposed for 4 of these; identifications are proposed for \18 other sources.
Proton Decoration of Halite Crystals
Authors: Bird JR , Rose A , Wilkins RWT
Published: June 2013

The decoration of glide bands and other features of halite crystals (NaCl) has been shown to result from proton irradiation at temperatures in the range 150-220�C. Optical transmission measurements before, during and after irradiation give very similar res'ults to those reported from studies of colour centres in synthetic NaCI. However, decoration is found to depend on the sequence of irradiation, exposure to light and the duration of sample heating. Both normal and colour-reversed bands have been observed for conditions leading to a final colour ranging from yellow/brown through blueto red/violet.
High-field Polynomial Expansions for the Six-state Planar Potts Model
Authors: N Barber Michael , Enting IG
Published: June 2013

High-field polynomial expansions (through order 9) are derived for the six-state planar Potts model and analysed. Suggestive evidence is found for an intermediate phase in which the exponent 0 varies continuously as a function of temperature. This behaviour is consistent with recent results predicting that the model exhibits two transitions separating a 'topologically ordered' phase analogous to that found in the planar rotor model.
A Collective Model Description of the Dipole States in the Even?Even N = 28 Isotones
Authors: Weise J
Published: June 2013

The photoabsorption and photon scattering cross sections for the even-even (N = 28) isotones 5OTi, 52Cr and 54Fe are calculated within the framework of the Gneuss-Greiner model and in the light of recent data.
The Effect of Diffusion on the Analysis of Pulsed Radiolysis Drift Tube Experiments
Authors: Cassidy RA
Published: June 2013

Electron drift velocities have previously been calculated from the transient waveforms recorded with a pulsed radiolysis drift tube (PRDT) using a first order theory in which it is assumed that diffusion during the drift of the electrons to the anode effectively increases the drift distance. In this paper the modifications to the transient waveforms caused by diffusion have been analysed more accurately by using a model representation of a group of electrons drifting and diffusing in a uniform electric field between plane, parallel absorbing electrodes. It is shown that, when account is taken of loss of electrons to the electrodes by diffusion, the correction factor differs in both magnitude and sign from that assumed in the first order theory.
Thermal Expansion of Zinc Sulfide: 300?1300 K
Authors: Roberts RB , White GK , Sabine TM
Published: June 2013

The thermal expansion of hot-pressed cubic polycrystalline zinc sulfide (Eastman Kodak: Irtran 2) was measured in a silica pushrod dilatometer. The coefficient of linear thermal expansion varies almost linearly from 6'9xlO- 6 K-l at 300K to lO'3xlO- 6 K-l at 1200K. The temperature variation of the Debye--Waller factor is calculated and compared with the experimental values found by Moss et al. (1980).
Observations of the Jupiter S-bursts between 3·2 and 32 MHz
Authors: Ellis GRA
Published: June 2013

Observations of the Jupiter S-bursts in the frequency range 3� 2-32 MHz are described. Their general properties including bandwidth, time duration, frequency-time behaviour, and rate of occurrence within this frequency range are analysed and discussed.
Exact Solutions of the Heisenberg Equations and Zitterbewegung of the Electron in a Constant Uniform Magnetic Field
Authors: Barut AO , Bracken AJ
Published: June 2013

For a free Dirac electron, the Heisenberg equations define an internal dynamical system in the rest frame, isomorphic to a finite three-dimensional oscillator with a compact SO(5) phase space, such that the spin of the electron is the orbital angular momentum of the internal dynamics (Barut and Bracken 1980, 1981a). In the present work, the change in this internal dynamics due to an external magnetic field is studied. In order that the internal motion can be distinguished from the centre of mass motion, the solutions of the corresponding Hamilton and Heisenberg equations for the relativistic classical motion and the relativistic quantum mechanical spinless motion are also presented. The solutions for the electron exhibit the effect of the spin terms both in the internal motion and external motion, and we are able to identify the properties of the Zitterbewegung in the external field.
Relative Yields of Stable Tellurium Isotopes in Neutron-induced Fission
Authors: de Laeter JR , Rosman KJR , Boldeman JW
Published: June 2013

The relative isotopic abundances of four isotopes of tellurium (125, 126, 128 and 130) produced in the thermal neutron fission of 233U and 23SU have been measured for the first time by solid source mass spectrometry. Samples of 233U and 23SU were irradiated in a reactor and chemically separated by ion exchange techniques to permit nanogram-sized samples of fission product tellurium to be analysed mass spectrometrically. The results for 23SU are in good agreement with published radiometric values, whereas our results for 233U are the first experimental measurements in this mass range. The cumulative fission yields determined by mass spectrometry for ruthenium, palladium, cadmium, tin and tellurium show a smooth mass distribution in the symmetric region for both 233U and 235U, except for a significant depression in the yield curve in the range 111-14.
Some Theorems Concerning Group Representations Generated by Determinantal Wavefunctions
Authors: Duff KJ
Published: June 2013

Theorems are developed which extend to representations more general than those of the rotation group the usefulness of the concept of filled fermion shells, and the relationships between shells containing and shells lacking n fermions.
Dependence on Declination of the Intensity of Cosmic Ray Showers with Primary Energies of about 1016 eV
Authors: Clay RW , Gerhardy PR
Published: June 2013

The declination isotropy of cosmic ray showers of energies of about 10'6 eV is studied using data from the Buckland Park extensive air shower (EAS) array and compared with measurements available through an analysis of data in the literature. It appears that an upper limit can be set to the anisotropy in declination at this energy of ~ 3, 5 %, limited by timing uncertainties in array directional measurements
Infrared Laser Spectroscopy of Molecular Beams
Authors: Boughton CV , Miller RE , Watts RO
Published: June 2013

A newly constructed crossed molecular beam apparatus and tunable infrared laser system is described. The Doppler effect has been used to measure the narrow velocity distribution in a molecular beam formed from a free jet expansion and to study the translational relaxation which occurs downstream of the nozzle orifice. In addition a laser-crossed molecular beam experiment is described which is designed to measure the rotational and vibrational state dependence of the total scattering cross section of hydrogen fluoride with helium.
Relativistic Intermediate-coupling Calculations for Ions of the Beryllium Isoelectronic Sequence
Authors: Glass R
Published: June 2013

Relativistic intermediate-coupling wavefunctions are used to evaluate wavelengths and oscillator strengths for the resonance transition 2S2 'SO -+ 2s2p 'P~ and the intercombination transition 2S2 'SO -+ 2s2p 3p~ for iron, krypton, molybdenum and tungsten beryllium-like ions. The convergence of the results with respect to the basis set of orbitals is considered. It is shown that the same degree of accuracy can be achieved by using the three configuration basis composed of 2S2, 2s2p and 2p2. The question of at what stage the Breit interactions should be included in the Hamiltonian is discussed. We also compare our calculated 2S2 'SO -+ 2s2p 3p~ intercombination oscillator strengths with those deduced from beam-foil experiments for iron and krypton
The Role of Electron Microscopy in Materials Science
Authors: Hirsch PB
Published: June 2013

The properties of the materials in a component or a device depend on structure and composition often on a scale of 10-10 to 10-6 m. Electron microscopy and microanalytical techniques provide a powerful means for determining the structure and composition on the appropriate scale, lead to an understanding of basic mechanisms, and by correlation or in situ experiments to explanations of bulk properties. Examples are given of the application of a variety of powerful electron optical techniques to a number of materials problems.
Some Applications of Transformation to the Space?independent Frame in the Processes of Strong Radiation in Plasmas
Authors: PauI SN , Chakraborty B
Published: June 2013

Transformation of nonlinear plasma equations from a lab frame S to the space-independent frame S' (both inertial) for an electromagnetic (EM) wave in an unbounded plasma reduces the nonlinear partial differential equations in S to ordinary nonlinear differential equations in S'. This relativistically correct transformation is used (1) to find the intensity induced precessional rotation of the polarization ellipse of vibration of an EM wave, (2) in the S-frame Lagrangian of the particles and field produced by them to derive the exact nonlinearly correct dispersion relation for a strong circularly polarized wave in a cold unmagnetized plasma, and (3) to rectify some much discussed differential equations obtained by Akhiezer and Polovin (1956) to study the evolution of longitudinal and transverse waves in a cold plasma.
Effective Hamiltonians and Wavefunctions for Electrons in Deformed Crystals
Authors: Brown RA
Published: June 2013

An effective Hamiltonian for electrons in in homogeneously deformed crystals is derived by expanding the wavefunction in terms of Wannier functions of the homogeneously deformed crystal. The physical interpretation of the modulating functions which determine the amplitude of each Wannier function in the expansion, and which are governed by the effective Hamiltonian, is investigated. This leads to strain-dependent expressions for the probability density and current, averaged over the fluctuations within each unit cell. The operators which represent, in the Hilbert space of the . modulating functions, similarly averaged physical observables are introduced and explicit straindependent expressions for the velocity and momentum operators are obtained. Applications of the theory are foreshadowed and its relationship to previous deformation-potential theories is examined.
Atlas of Main-line OH Masers in the Galactic Longitude Range 3° to 60°
Authors: Caswell JL , Haynes RF
Published: June 2013

We tabulate all 55 OH main-line masers discovered to date in the galactic plane between longitude 3� and 60�. For most of these we show current spectra, which have been taken with the Parkes 64 m radio telescope, in both senses of circular polarization on the 1665 MHz and/or 1667 MHz transitions; for some sources we give new position estimates, and several sources are reported for the first time. We discuss many sources individually and note that while most of the main-line OH masers probably pinpoint compact HII regions and sites of current star formation, a few appear to be unusual varieties occurring in circumstellar shells, possibly associated with late-type stars.
The Quark Presence in Nuclei
Authors: Brown GE
Published: June 2013

The strong short-range repulsion seen in the nucleon-nucleon interaction is, in the classical solution discussed here, produced by the loss of mean-field pion energy when two three-quark systems are pushed on top of each other. The intermediate- and long-range interactions come from boson exchange.
Formal Scattering Theory for Energy-dependent Potentials
Authors: HJ McKellar Bruce , M McKay Colette
Published: June 2013

We show how the usual results of formal scattering theory should be modifted when the two particle potential is energy dependent.
Isospin Mixing in 4¯ States of 12C
Authors: Barker FC
Published: June 2013

Fits are made to measured 12C(n�,no:)12C cross sections in terms of an isospin-mixed doublet of 4- 12C levels near 19�5 MeV, using the R-matrix theory of nuclear reactions. Parameter values are restricted by information from other reactions and from bound-state shell model calculations.
Remarks on the Motility and Thermotactic Response of Fibroblasts
Authors: Parkinson WC
Published: June 2013

The motion of mouse L cells (fibroblast) in vitro is studied by means of time-lapse photography. In particular, the response of the cells to a temperature gradient of7� 22�Ccm-1 is studied for several temperatures from 32� 6�C to 39� 7�C. Three measures of the thermotactic response are used: (1) the motility, defined in terms of the mean-square displacement of an ensemble of cells, (2) the displacement of the centre of gravity of an ensemble of cells versus time, and (3) the distribution in the number of cells in an ensemble moving up the gradient compared with the number moving down the gradient. There is no evidence of a thermotactic response as determined by these three measures. The variance in the data can be understood in terms of statistical fluctuations.
Generalized Einstein Relation and Negative Differential Conductivity in Gases
Authors: Robson RE
Published: June 2013

Transport coefficients of charged particles undergoing both elastic and inelastic collisions with a gas of neutral molecules are calculated using momentum-transfer theory. A criterion is obtained for the phenomenon of negative differential conductivity (i.e. the drift velocity decreasing with applied electric field) and the well-known generalized Einstein relation is appropriately modified.
A Guide to the Determination of Operational Parameters in the Conventional X-ray Diffractometry of a Small Single Crystal
Authors: McL Mathieson A
Published: June 2013

There are two important operational parameters in conventional X-ray diffractometry of small crystals-scan range and detector aperture size. These parameters depend on a number of experimental factors, the main ones being the crystal mosaic spread u, the source size a and the wavelength distribution 2. Earlier theoretical analyses did not provide a procedure for establishing realistic estimates of these in an actual experimental set-up. Therefore, scan range and detector aperture size have been determined, not from the physical features of the experiment, but by ad hoc decisions, sometimes not far removed from 'guesstimates'. By considering the (L\w, L\20) intensity distribution (Mathieson 1982) and by the selection of appropriate scan modes, it is possible to obtain experimental estimates of suitable outer limits of u, a and 2, namely a/u auand bA , and hence to determine appropriate values of the scan range and aperture size for the reflections to be examined. From a comparison of an example using this method with previously published parameters, it is concluded that, in the majority of past cases of conventional analyses, the scan and aperture parameters chosen led (a) to a progressively decreasing L\A bandwidth as 0 ~ 90� and hence to erroneous determinations of temperature factors -a recognized defect-and (b) to a largely unrecognized defect, namely an overestimation of integrated intensity as 0 ~ 0�, corresponding to a significant source of systematic error which could conceal the true extent of extinction.
Collision-induced Spectra at a Gas-Solid Interface
Authors: Mahanty J
Published: June 2013

In analogy with collision-induced translational absorption in the far infrared in binary mixtures of inert gases, it is suggested that a similar process mustoccur at a gas-solid interface. Each gas molecule develops a dipole moment that depends on its distance from the surface, and its time dependence due to the thermal motion of the molecule should cause optical activity. The necessary theory and expected absorption curves for a typical model are given:
Trivial Solution to the Domain Wall Problem
Authors: Christos GA
Published: June 2013

The domain wall problem only arises if one makes the unrealistic pure gauge assumption. The problem is avoided altogether by relaxing this assumption. Recently much attention has been devoted to solving the domain wall problem (Sikivie 1982). Our contention is that the problem does not really exist. The domain wall problem arises because it is commonly believed that the anomaly (via instantons) explicitly" breaks V(l) axial invariance down to the centre ZL (where L is the number of light quark flavours). The subsequent spontaneous breaking] of this centre by the QeD condensate
The LT-4 Tokamak. I. Description of the Apparatus and Its Operation
Authors: Bell MG , Cheetham AD , Hamberger SM , Hogg GR , Hollis MJ , How JA , Kuwahara H , Morton AH , Sharp LE , Whitbourn LB , Vance CF
Published: June 2013

The LT-4 is a relatively small (major radius 0�5 m, minor radius 1'10� 1 m) experimental tokamak using a homopolar generator as its main power source to produce a toroidal field of 3 T. A fast currentforcing feedback control system maintains the plasma position constant to 1'1 1 mm. Fairly standard diagnostics are supported by a data acquisition system which handles 200 kbytes of data through 70 CAMAC controlled ADCs per discharge. Illustrative examples of data obtained during .typical operation show magnetohydrodynamic (MHD) activity (magnetic pick-up coils and soft X-ray detectors) as well as relaxation oscillations within the plasma.
El Decay of the First Excited State of 9Be
Authors: Barker FC
Published: June 2013

The E1 decay strength of the t + first excited state of 9Be is calculated using R-matrix formulae in which the excited state is correctly treated as unbound. Agreement with experiment is obtained for a reasonable choice of channel radius.
Derivation of Muon Intensities in Sea-water Depths up to 1400 M.W.E. from a Recent Primary Cosmic Ray Spectrum
Authors: Bhattacharyya DP , Pal Pratibha , Mukhopadhyay A
Published: June 2013

The muon intensities in sea-water depths up to 1400 M.W.E. have been derived from a recent primary cosmic ray spectrum. The scaling hypothesis of Feynman has been used in the calculation of meson spectra in the atmosphere. The range-energy relation for muons in sea water, used in the present work, accounts for the muon energy loss in sea water due to collisions, pair production, bremsstrahlung and nuclear interactions. The calculated muon range spectrum in sea water is well in accord with the experimental data obtained by Higashi et al. (1966), Davitaev et al. (1969), and Rogers and Tristam (1981, 1983
An Improved Technique for Examining Bragg Reflections in Dw, D2q(s) Space
Authors: McL Mathieson A , Stevenson AW
Published: June 2013

With a standard X-ray tube line source set at right angles to the diffraction plane of a diffractometer and with the usual tube take-off angle, one can obtain, without loss of peak intensity in the Bragg peak, a source which is effectively very small (~50 pm) in relation to the diffraction plane. The measured two-dimensional distribution I(A(f), A28(S� of a Bragg reflection from a small single crystal then has effectively only two principal components, namely, the mosaic spread of the specimen crystal and the wavelength distribution of the source.
Molecular Dynamics of the Phase Transition in Compressible Ammonium Chloride
Authors: Pandey Sadhana , Trikha SK
Published: June 2013

The effects of pressure on the dynamical behaviour of an NH: ion near the A transition under the influence of its nearest neighbours in ammonium chloride have been studied by using the computer simulation technique. The Lennard Jones (6-12) potential is used as the representative interaction between NH: and Cl-. The present calculations reveal a decrease in entropy of the system with increasing pressure. The libration frequency of the NH: ion is estimated to be approximately 170, 182 and 210 cm -1 at pressures of 1 atm, 3 and 10 kbar respectively, in agreement with the Raman spectrum study of NH4CI at high pressure (Ebisuzaki and Nicol 1969).
The Dynamics of Steady Hexagonal Magnetoconvection
Authors: Murphy JO , Lopez JM
Published: June 2013

The dynamic interaction between an initially uniform vertical magnetic field and a Rayleigh-Benard type layer of convecting fluid is investigated under steady-state conditions. Particular attention is given to the roles of the dtffusivities in determining the extent to which a magnetic field is induced and convective motions inhibited. The model demonstrates how the perturbed magnetic field is generated at the base of the convection zone, which is a region of converging fluid flow, and is expelled from regions of divergent flow.
Variational Theory of Reflection
Authors: Lekner John
Published: June 2013

Schwinger's variational method for the scattering phase shift produced by a central potential is adapted to reflection by a planar potential barrier (or well). The formulation is general, for an arbitrary transition between any two media, but the application here is limited to reflection at a barrier between media of equal potential energy. The simplest variational estimate for the reflection amplitude correctly tends to -1 at grazing incidence, as it must for any finite barrier. This is in contrast to the first order perturbation reflection amplitude, which diverges at grazing incidence. The same variational estimate is also correct to second order in the ratio of the interface thickness to the wavelength of the incident wave. The theory applies also to the reflection of the electromagnetic s (or transverse electric) wave at an interface between two media.
The Existence of Non-unique Steady State Solutions to the RMF Current Drive Equations
Authors: Hugrass WN
Published: June 2013

It is shown that the value of the d.c. current driven in a plasma cylinder by means of a rotating magnetic field (RMF) is not unique for R/o ;;:; 6 and eB",/vel m ~ R/o, where R is the radius of the plasma cylinder, a is the classical skin depth, Vel is the electron-ion momentum transfer collision frequency, B", is the magnitude of the rotating magnetic field, e is the electron charge and m is the electron mass. This effect is predicted using three distinct approaches: (i) a steady state analysis which ignores the second and higher harmonics of the fields and currents; (ii) a qualitative model which utilizes the analogy between the RMF current drive technique and the operation of the induction motor; (iii) a solution of the initial boundary value equations describing the RMF current drive in cylindrical plasmas.
Atomic Contribution to Crystalline Property Temperature Dependence
Authors: Abrahams SC
Published: June 2013

General atomic locations in crystal structures are temperature dependent: the average thermal change in simple inorganic crystals is of the order of 10 - 3 A K - 1, with corresponding thermal coefficients of about 10 - 3 K - 1. A survey of the thermal coefficients for seven important crystal properties shows that these also have average values of about 10 - 3 K - 1, within one order of magnitude. Correlations between microscopic and macroscopic thermal dependence have been developed for the properties of spontaneous polarization and spontaneous strain. Comparable correlations are predicted for the case of piezoelectric strain. Scaling considerations suggest that the remaining dielectric, thermal and optical properties are similarly related to atomic location thermal coefficients. By contrast, the much smaller thermal dependence of such properties as expansivity and refractive index, with coefficients of about 10 - 5 K - 1, suggests that these properties are dominated by electronic rather than ionic interactions.
X-ray Collimation for Protein Crystallography
Authors: Arndt UW , Thomas DJ
Published: June 2013

Native protein crystals frequently exhibit a very low mosaicity: the mosaic blocks are large and their relative mis-orientation is small. With suitable collimation it is possible to make use of this perfection so as to obtain diffraction profiles with a very narrow width and, accordingly, to improve the spot-to-background ratio and to increase the recorded intensity.
A Comparison between Electron Crystal Scattering Potentials derived from X-ray Electron Densities and from Atom Muffin Tin Potentials
Authors: E Smith Andrew , Lynch DF
Published: June 2013

Two different forms of electron crystal potential are compared for the particular cases of aluminium and niobium diselenide. One of these is the solid-state muffin tin potential frequently used for band structure and low energy electron diffraction problems, and with its natural representation in real space. The other potential, derived from X-ray structure factors, is that most commonly used in electron microscopy structure determinations. It is expressed in terms of its Fourier coefficients and is accordingly a reciprocal space representation. Comparisons are carried out in both spaces. It is concluded that differences between the potentials are only minor and are mainly due to details in truncation and superposition.
Solving Crystal Structures from Powder Diffraction Data
Authors: Nørlund Christensen A , Lehmann MS , Nielsen M
Published: June 2013

High resolution powder data from both neutron and X-ray (synchrotron) sources have been used to estimate the possibility of direct structure determination from powder data. Two known structures were resolved by direct methods with neutron and X-ray data. With synchrotron X-ray data, the measured range of data was insufficient for a structure analysis, but the R-factor calculations showed the intensities extracted from the profile data to be of acceptable quality. The results were used to estimate the largest structure that might be solved using routine techniques. It was found that the limit would be near twenty atoms in the asymmetric part of a centro-symmetric structure.
The Large Number Hypothesis and Einstein's Theory of Gravitation
Authors: Lau Yun-Kau
Published: June 2013

In an attempt to reconcile the large number hypothesis (LNH) with Einstein's theory of gravitation, a tentative generalization of Einstein's field equations with time-dependent cosmological and gravitational constants is proposed. A cosmological model consistent with the LNH is deduced. The coupling formula of the cosmological constant with matter is found, and as a consequence, the time-dependent formulae of the cosmological constant and the mean matter density of the Universe at the present epoch are then found. Einstein's theory of gravitation, whether with a zero or nonzero cosmological constant, becomes a limiting case of the new generalized field equations after the early epoch.