bluuebunny/crossref_metadata_2025 huggingface dataset:
Static Theory of a Discharge Column at Intermediate Pressures
Authors: Self S. A. , Ewald H. N.
Published: December 2004

A steady-state theory of the discharge column is derived which is applicable in the pressure range where the ion mean free path is neither much greater than nor much less than the column radius, and which goes over in the low- and high-pressure limits to the free-fall and ambipolar diffusion theories, respectively. Solutions for planar and cylindrical geometry are given for the density and potential profiles. The plasma-sheath boundary is discussed and the sheath potential drop is estimated. The theory is shown to agree well with measurements in mercury discharges over the pressure range 1–20 μ Hg.
Rotating Plasma Experiments in the B-3 Stellarator
Authors: Gorman J. G. , Rietjens L. H. Th.
Published: December 2004

A radial electric field can be imposed on the plasma column of a stellarator by means of a comparatively large, positively biased Langmuir probe. Measurements are presented which confirm the theoretical description of the resulting E × B rotation in terms of a leaky plasma capacitor; the leakage is caused most likely by resonant charge exchange collisions with neutral atoms. The plasma loss rate is changed in the rotating region; a decrease in loss rate by a factor 8 can be realized; too large a rotational velocity causes the loss rate to increase again. Comparisons are made with other experiments and theories. The experiments were carried out in highly ionized hydrogen and deuterium plasmas created by Ohmic heating in the B-3 stellarator, having electron temperatures of 3 to 5 eV, densities of 2 to 20 × 1012 cm−3, and confined in magnetic fields of 25 to 40 kG. An experimental justification for the interpretation of Langmuir probe characteristics under these conditions is given.
Investigation of the Kelvin-Helmholtz Instability in a Cesium Plasma
Authors: D'Angelo N. , Goeler S. v.
Published: December 2004

Experiments have been performed in a thermally ionized cesium plasma, in which a relative drift between ions in adjacent layers appears to excite the Kelvin-Helmholtz instability. The relative drifts required are of the order of ci, the ion thermal velocity, or somewhat smaller. The frequency of the oscillations is generally in the range 1–4 kc/sec. A study has been made of the type of waves excited, by means of amplitude and phase measurements.
Magnetohydrodynamic Shocks in Nonaligned Flow
Authors: Lynn Y. M.
Published: December 2004

The transition solution across a plane nonrelativistic magnetohydrodynamic shock of finite strength in nonaligned flow in a perfect gas is investigated. A unified point of view is taken to analyze shocks in both one-dimensional unsteady flow and two-dimensional steady flow for which a set of conversion formulas connecting pertinent parameters in these two cases is given. We present a convenient parametric representation of the shock solution from which an analytical solution expressed in terms of any desirable shock-strength parameter can be readily obtained by performing a straightforward calculation. Detailed analytical and numerical solutions expressed in terms of the flow deflection angle across the shock which is most often prescribed in two-dimensional steady flow are then given, with entire ranges of all upstream parameters being covered. Limiting solutions for several special cases are derived. We illustrate the connection of the present general solution with several other major results in the literature. Dynamical stability criteria associated with general magnetohydrodynamic shocks are discussed.
Density Expansions of the Transport Coefficients for a Moderately Dense Gas
Authors: Chaos F. , García-Colín L. S.
Published: December 2004

A comparison is made between three different methods used for computing the transport coefficients of a moderately dense gas to all orders in the density. These methods are the correlation function approach and two methods based on a generalized Boltzmann equation which differ in their different definitions of temperature. It is found that all three methods yield the same results for the thermal conductivity and the shear viscosity to all orders in the density. However, the results for the bulk viscosity are identical for all three methods, only to first order in the density. To all orders in the density the values for this transport coefficient are different if different definitions of local temperature are adopted. Also, we find that the lowest-order contribution to the bulk viscosity is quadratic in the density.
Spectroscopic Determination of Electron Temperature in a Helium Plasma
Authors: De Vries R. F. , Mewe R.
Published: December 2004

Optical excitation functions measured in collision chamber experiments should be applied with caution on plasma diagnostics. This is illustrated for the upper level (41S) of λ5048 of neutral helium.
Shock-Tube Measurement of Vibrational Relaxation Times in Deuterium
Authors: Moreno James B.
Published: December 2004

The vibrational relaxation times of deuterium in argon and in krypton were determined at temperatures between 1200 and 2300°K. The relaxations were initiated by shock-heating the gas mixtures in a shock tube. The relaxation times were inferred from recordings of the density profiles behind the shock waves, as measured by the schlieren-photomultiplier technique. The results are fitted by the relations pτ̄D2−D2 = 0.79 × 10−10 exp (125/T̄⅓) atm-sec, pτ̄D2−Ar = 3.8 × 10−10 exp (125/T̄⅓) atm-sec, pτ̄D2−Kr = 1.3 × 10−9 exp (125/T̄⅓) atm-sec. The density change measured in the relaxation region was 57% ± 19% of the change calculated to arise from vibrational equilibration. This was taken to indicate that the measured relaxation was that of ortho-deuterium and that para-deuterium relaxed considerably faster.
Quantum Kinetic Equations for Unstable Plasmas
Authors: Matsudaira Noboru
Published: December 2004

A treatment of the transport equation for a classical unstable electron plasma by K. Nishikawa and Y. Osaka [Progr. Theoret. Phys. (Kyoto) 33, 402 (1965)] is extended to the quantum-mechanical multicomponent case. The quantum Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy of equations is truncated at the second stage, and the technique due to Dupree is employed. In the limit of weak instability, the kinetic equation, that proves to be the direct extension of the classical case, can be rewritten in the form of a set of simultaneous equations, the form of which agrees completely with the equations proposed by Pines and Schrieffer.
Interfacial Instability of a Liquid with Constant Shear
Authors: Rajappa N. R. , Chang I. D.
Published: December 2004

The Taylor-Helmholtz instability between a liquid of constant shear and a vacuum is studied, and it is found that a more stable flow will be resulted from the shear if the speed of the liquid increases as depth increases.
Laser-Generated Implosions
Authors: Daiber J. W. , Hertzberg A. , Wittliff C. E.
Published: December 2004

By using a weak spherical blast wave to shape the initial density distribution, the laser energy can be preferentially coupled to the periphery of this sphere. This energy addition to the shell of high density gas then produces an imploding plasma.
Magnetohydrodynamic Flow in the Inlet Region of a Straight Channel
Authors: Brandt A. , Gillis J.
Published: December 2004

The flow is considered of an incompressible conducting viscous fluid in the inlet region of a straight channel in the presence of a transverse magnetic field. The complete equations are solved numerically without any approximating assumptions. Various characteristics of the flow and their dependence on the physical parameters are deduced. Values of Reynolds number up to 500 are considered. Velocity profiles near the inlet are found to have points of inflection. The distance to the terminal regime is studied, and the results, in the limiting case of large Reynolds number, compared with those of other workers. The boundary layer thickness is found to be proportional to xα (for a small range of x) where α ≈ 1.2 at zero Reynolds number and decreases to 0.5 as the Reynolds number increases. The exact pressure distribution is also obtained.
Small Signal Energy Conservation Theorem for Multivelocity Electron Beams
Authors: Bobroff D. L.
Published: December 2004

The small signal energy conservation theorems for one-dimensional multivelocity electron beams are obtained for both the Boltzmann and the multistream descriptions. The relationship between the theorems in the two descriptions is discussed.
Hot-Electron Plasma Stability in Mirror and Minimum-B Containment Systems
Authors: Hartman Charles W.
Published: December 2004

In all configurations which have ``saddle in B'' fields, independent of shear, a dominant cross-field loss is observed which can be suppressed by a cold-plasma background. In minimum-B fields, cross-field loss is suppressed independent of the cold plasma.
Ionizing Switch-On Shock Waves
Authors: Gross R. A. , Levine L. , Geldon F.
Published: December 2004

A physical model is presented for the development of a uniquely determined ionizing shock wave and associated electric field in a coaxial electromagnetic shock tube. Numerical solutions of the jump conditions are given.
Nonlinear Scattering of a Laser Beam by a Plasma
Authors: Comisar G. G.
Published: December 2004

Using a simple free-electron theory it is shown that an intense light beam can stimulate coherent electron-density fluctuations in a gaseous plasma via the v×B nonlinearity. The possibility of observing scattered light at the third harmonic of the incident beam with laser techniques is discussed.
Free-Streaming and Landau Damping
Authors: Gunshor R. L.
Published: December 2004

A simple technique is used to express the ballistic or free-streaming response implicit in Landau's theory. In a gas characterized by Coulomb interactions, this response is shown to be equivalent to the free-streaming of noninteracting particles.
Shock Front Curvature at Initial Pressures up to 700 mm Hg
Authors: Mazzella A. T. , De Boer P. C. T.
Published: December 2004

Axial extents of curved shock fronts in argon were measured using thin film heat transfer gauges mounted on a plate perpendicular to the axis of a 1½-in.-diam shock tube. In interpreting the data, use was made of the theoretical shock shape. This shape was determined from previously derived formulas which apply when the boundary layer behind the shock is either laminar or turbulent, and which account in an approximate way for the influence of the flow at the foot of the shock. At low initial pressures the experimental data obtained agree well with theory and with results of other investigators. For initial pressures above 100 mm Hg, the data showed appreciable scatter, which is taken to indicate that the shock is oscillating in curvature. The scatter has the order of magnitude which follows from Freeman's theory for the damping of perturbations in shock shape, with the assumption that somewhere near the diaphragm the shock is strongly curved.
Plasma Motion and Confinement in a Toroidal Octupole Magnetic Field
Authors: Dory R. A. , Kerst D. W. , Meade D. M. , Wilson W. E. , Erickson C. W.
Published: December 2004

Plasma of approximately 100 eV in ion energy was injected into and trapped within an octupole magnetic field with closed lines of force contained within a toroidal region of magnetohydrodynamic stability. A zero-field locus was near the middle of the region, and fields of 1000 to 8000 G existed along the wall and around the current-carrying hoops forming the multipole field with 4.7 to 9.6 gyroradii across the stable plasma region. Observed electric fields caused by the self polarization charge at the edge of a moving plasma cloud enabled the injected plasma stream to penetrate the octupole field and to flow rapidly throughout the low-field region. The high-polarization potentials disappeared after 100 μsec as the trapped plasma evolved into a quiescent state having typically a lifetime of 0.4 msec for 100-eV ions. The electron temperature was approximately 10 eV at all times. Density fluctations and field fluctuations during confinement were negligibly small compared to those observed in plasmas afflicted with anomalous diffusion. Electric potential fluctuations were less than 2% of the electron temperature. This quiescent condition continued while the plasma density was smoothly decreasing by loss on probes and hoop supports.
Stability Limits for Longitudinal Waves In Ion Beam-Plasma Interaction
Authors: Fried Burton D. , Wong A. Y.
Published: December 2004

The two-stream instability is examined for the case of an ion beam traversing a plasma. The dispersion equation for linearized, longitudinal waves in a plasma where collisions are negligible is used to find the restrictions on beam velocity, temperature, and density which will lead to growing waves.
Computer Study of the Dynamic Phase of a Small θ-Pinch
Authors: Düchs D. , Griem H. R.
Published: December 2004

A three-fluid hydromagnetic computer code accounting for hydrogen or deuterium atoms, ions, and electrons is modified to include ionization and excitation of carbon and oxygen impurity ions. Results are presented for energy losses from impurity radiation and are compared with macroscopic and thermal kinetic energies of ions and electrons and with magnetic field energies. Although radiation losses exceed kinetic plasma energies at typical impurity concentrations, electron temperatures are only slightly reduced up to first maximum compression.
Magnetohydrodynamic Channel Entrance Flow with Parabolic Velocity at the Entry
Authors: Hwang C. L. , Li K. C. , Fan L. T.
Published: December 2004

A finite difference analysis is employed to investigate the laminar magnetohydrodynamic flow in the entrance region of a flat channel. The velocity is assumed to be parabolic (nonmagnetohydrodynamic fully developed) at the entry and develops to Hartmann velocity in this magnetohydrodynamic entrance region. Velocity profiles, entrance lengths, and pressure drops are numerically computed at values of the Hartmann number of 2.5, 4, 10, and 50. Values of the entrance length computed are compared with the only available results by Maciulaitis and Loeffler. The comparison shows a substantial difference.
Variational Approach to Boundary-Value Problems in Kinetic Theory
Authors: Cercignani Carlo , Pagani Carlo Domenico
Published: December 2004

A general variational principle applying to kinetic models is introduced. Then the principle is applied to three typical problems, i.e., Kramers' problem, plane Couette flow, and plane Poiseuille flow. With extremely simple trial functions, very accurate results are found.
Transport Properties of Ionized Monatomic Gases
Authors: Devoto R. S.
Published: December 2004

Expressions are developed with the Chapman-Enskog-Burnett method for the third and fourth approximations to the thermal conductivity and the diffusion coefficients, and for the second approximation to the viscosity of multicomponent gas mixtures. Special forms of these expressions are then derived for application to ionized gas mixtures, in particular to the partially ionized gas. Convergence of the approximations is checked by computing the properties of fully ionized hydrogen and of several other mixtures where the molecules interact with inverse-power repulsive potentials. From the results for hydrogen, it is seen that at least the third approximation should be used for the thermal conductivity and thermal diffusion coefficient, and the second approximation for the electrical conductivity and viscosity of ionized gases. These results contrast with those for un-ionized gases where one lower level of approximation is generally adequate.
Buoyancy Effects in Linearized, Relaxing Flow
Authors: Sforza Pasquale M.
Published: December 2004

Buoyancy effects in a convecting, ideal dissociating gas are studied by a small perturbation technique. Analytic solutions are obtained for one-dimensional unsteady free-mixing; the time-dependent system resembles that of steady free-mixing of jet or wake type, with two space coordinates.
Stability of Swirling Flow of a Viscous Conducting Fluid in the Presence of a Circular Magnetic Field
Authors: Pao Hsien-Ping
Published: December 2004

A sufficient condition for the stability of a swirling flow in a circular magnetic field, for the case of small spacing between cylinders, is established. A new branch of solution which corresponds to negative critical Taylor number is calculated.
Energy Change of a Charged Particle Moving in a Plasma
Authors: Itikawa Yukikazu , Aono Osamu
Published: December 2004

The energy loss rate of a charged particle moving in a plasma is calculated without any cutoff procedure. The result is applicable to any velocity of the test particle.
Cusp Compression of Colliding Plasma Blobs
Authors: Allen T. K. , Doble K. , Jones T. J. L. , Payne R. M. , Spalding I. J.
Published: December 2004

A plasma formed by colliding two plasma blobs is compressed by a rising cusp field which reaches 34 kG between the coils in 15 μsec. The plasma density and temperature rise to peak values of 1016/cm3 and 7 × 105 °K, 5–6 μsec after the start of the compression. The hole size measured at the ring cusp is one ion gyro-diameter wide, still an order of magnitude larger than predicted for a collision-free sheath having strong space-charge electric fields at the plasma boundary. The electron temperature is sufficiently high to ensure that the increase cannot be attributed simply to resistive diffusion. It is inferred that the measured hole size is determined either by short-circuiting of the space-charge fields at the walls or by microinstabilities in the sheath, but further experimental information is required to distinguish between these two possibilities. The measured containment time of 5–10 ion transits is consistent with that predicted using a simple two-fluid model of effusion through an ion gyro-diameter hole at the ring cusp, with a comparable loss through the spindle cusps.
Temperature Overshoot in Shock Waves
Authors: Yen Shee-Mang
Published: December 2004

Temperature associated with the logitudinal thermal velocities overshoots for M1 > (9/5)½ for monatomic gases. The overshoot and the location of the maximum temperature are functions of M1.
Electron-Beam Studies of Skimmer Interaction in a Free Jet
Authors: McMichael G. E. , French J. B.
Published: December 2004

Electron-beam flow-visualization study of the density field about the entry to a conical collimator (skimmer) placed in a small free jet suggests that the dominant mechanism for attenuation of nozzle-source molecular beams is inside rather than in front of the skimmer.
Relativistic Contribution to Landau Damping
Authors: Aaron R. , Currie D.
Published: December 2004

Using the collisionless Boltzmann equation, we study the asymptotic time behavior of longitudinal waves in a one-dimensional plasma of relativistic electrons and stationary ions. The electronic distribution function is assumed to be a perturbed Maxwell-Boltzmann distribution.
Minimum-B Properties of Relativistic Electron Coils
Authors: Christofilos N.
Published: December 2004

An absolute minimum-B configuration of closed magnetic lines is made possible by placing relativistic electron coils in a toroidal geometry, creating an absolute minimum-B well. The depth of the well required for hydromagnetic stability is derived from criteria developed for vacuum minimum-B geometries.
Equilibrium of a Toroidal Plasma in the Model C Stellarator
Authors: Young K. M. , Yoshikawa S. , Sinclair R. M.
Published: December 2004

The equilibrium of a toroidal magnetically-confined plasma has been investigated using a circular aperture limiter consisting of four conducting segments. The force acting on the limiter to counteract the expanding forces of the plasma is proportional to the current flowing between the top and bottom limiter segments. With no external rotational transform applied, this current varies with the plasma parameters in close accordance with theory. The application of external rotational transform provides equilibrium at high Ohmic heating current densities (>10 A/cm2), whereas it does not at lower currents. This experimental result is consistent with the hypothesis that the dominant cause of plasma loss at low Ohmic heating currents is just this lack of equilibrium.
Stabilizing Effect of Radial Plasma Density Distribution on Helical Instability
Authors: Adati K. , Iida Y. , Sekiguchi T. , Yamada N.
Published: December 2004

Stabilization of magnetoplasmas against the helical instability is experimentally demonstrated in plasma columns (∼4.5 m long) placed in the dc magnetic field below 0.7 Wb/m2 by means of the external control of the radial plasma density distribution. It is observed that the value of the critical magnetic field is raised above that for the usual Bessel distribution by a factor of five or higher. It is also observed that the stabilized and the turbulent region can stably coexist in a single plasma column. In the extended magnetic field region of stabilization, the particle diffusion is confirmed to be of the order of the classical one in cases of neon and argon and to be at least greatly reduced in helium as compared with that in the usual fully developed turbulent state. The possible physical mechanisms for the observed phenomenon are also discussed.
Collisionless Damping of Hydromagnetic Waves
Authors: Barnes Aaron
Published: December 2004

Numerical solutions have been obtained for the dispersion relation for hydromagnetic waves in an infinite, uniform, collisionless plasma. Except for the Alfvén (shear) mode, all hydromagnetic waves are strongly damped in plasmas of moderate or high β (fluid pressure/magnetic pressure). For β greater than about ½, the damping factor W=−Im (ω)/|Re (ω)| is a few percent greater for the fast mode (except for special directions of propagation) and of order ½ for the slow mode. The least damped (fast) magnetosonic mode exhibits two maxima in a plot of W versus the angle θ between the wave vector k and the static magnetic field: the first maximum occurs for θ between 20° and 40° and is associated with ion heating; the second occurs between 85° and 89° and is associated with electron heating. In addition, the modes associated with the ``hose'' and ``mirror'' plasma instabilities are considered in some detail.
Traveling-Wave Induced Electroconvection
Authors: Melcher James R.
Published: December 2004

An electrohydrodynamic traveling-wave induction interaction is shown to pump slightly conducting liquids [electrical conductivities 10−5 to 10−15 (Ω·m)−1] without electrical contact with the flow. A gradient in fluid conductivity perpendicular to the direction of flow is required. Here, this is provided by a liquid interface, which is exposed to a traveling potential wave imposed by means of a segmented electrode parallel to the interface. Induced charges relax through the liquid to form a traveling wave of surface charge on the interface which lags the wave of image surface charges on the electrode. Hence, a time-average electrical surface traction is produced tending to make the fluid move with the traveling wave. Expressions for the fields, the time-average electric traction and the fluid velocity (in plane flow) are derived and discussed. Experiments illustrate the validity of these equations and tend to support the model used for the interfacial conduction process.
Equilibrium Structure of Thin Diffusion Flame Zone
Authors: Chung Paul M. , Blankenship Victor D.
Published: December 2004

The method of inner-and-outer expansions was used to analyze the initial broadening of a diffusion flame sheet caused by the nonvanishing equilibrium constant. Analytic expressions are derived for the thickness of the flame zone and the position and the value of the maximum flame temperature. The thickness of the flame zone created by the nonvanishing equilibrium constant is found to be less than that created by the decreasing Damkohler number studied previously. Varying the stoichiometric coefficient of the fuel is found to affect the oxidant side of the flow to a greater degree than the fuel side itself, and vice versa.
Flame-Temperature Measurement by Thermal Neutron Probe
Authors: Doherty P. D. , Barr R. E. , Boedeker R. R. , Delaney R. M. , Manson D. J. , Weber A. H.
Published: December 2004

Thermal neutrons from the CP-5 reactor at Argonne National Laboratory were scattered from an oxyhydrogen flame. Simple analysis shows that the energy distribution of the scattered neutrons depends on the translational motion temperature of the flame nuclei. The energy distribution was calculated assuming Maxwell-Boltzmann statistics in the flame and averaging over the energy distribution of the incident thermal neutrons. The measured transmission of the scattered neutrons by thin cadmium foils plotted versus foil thickness (0.001–0.015 in.) is compared with calculated plots yielding the translational motion temperature. The temperature determined in this way for a flame at ambient pressures from 20 to 30 Torr is 2800 ± 400°K.
Correlation Functions for Dilute Systems
Authors: McLennan James A.
Published: December 2004

Space- and time-dependent correlation functions are considered for particles undergoing Brownian motion and for a low-density gas described by the Boltzmann equation. A Fourier transform is performed with respect to the space coordinates, and a Laplace transform with respect to time, the transform variables being k and −z. It is shown that the transformed correlation functions contain a hydrodynamic pole at z = p(k), where p(k) is a dispersion relation obtained from the hydrodynamic equations. In addition, there are singularities corresponding to microscopic relaxation. For the case of Brownian motion, these are a sequence of poles accumulating at infinity. For the Boltzmann equation, there is, for k → 0, a branch cut along part of the positive real axis, while for finite k the branch cut opens out into a singular region within which the correlation functions are undefined.
Asymptotic Formulas for the Virial Coefficients using the Exponential Repulsive Potential
Authors: Henderson Douglas , Oden Lynn
Published: December 2004

An asymptotic formula for the equation of state is derived using the exponential repulsive potential. This result confirms the formulas which Amdur, Mason, and Vanderslice have proposed, without proof, for the third and fourth virial coefficients and is identical to the asymptotic formula of Mason and Vanderslice for the second virial coefficient. The asymptotic formulas for the second, third, and fourth virial coefficients are checked by direct calculation and are found to be reliable.
Theoretical Optimum Seed Concentrations in Slightly Ionized Nonequilibrium Plasmas
Authors: Smith J. Marlin , Shair F. H.
Published: December 2004

Optimum concentration of an alkali metal seed in a noble gas for maximum electrical conductivity is derived for a nonequilibrium plasma in which the nonequilibrium is caused by an applied or induced electric field.
New Statistical Models for Kinetic Theory: Methods of Construction
Authors: Holway Lowell H.
Published: December 2004

A statistical model of the collision term in the Boltzmann equation is introduced which is similar in concept to the well-known Krook model but yields the correct Prandtl number of ⅔ for a monatomic gas. A new method for constructing kinetic models is presented which is based on the information theory concept of entropy or uncertainty. This method, which is applicable to quite general systems in nonequilibrium statistical mechanics, is used to construct statistical models for multicomponent gas mixtures and for gases consisting of molecules with internal degrees of freedom.
Random Phase Approximation for a Plasma in an External Electric Field
Authors: Livingston P. M.
Published: December 2004

A new method for establishing the perturbed electron distribution in an oscillating external, homogeneous electric field is demonstrated. A Green's function for single-particle motion in the external field is averaged over a random distribution of starting phases. It is shown that in time intervals longer than the period of the field, acceleration effects are dropped, and one finds a simple Laplace transform of the averaged Green's function. The latter remains a function of the electric field, however, and when written in the solution of the linear Vlasov equation, gives a distorted electron distribution in the electric field directions. If a Lorentz model for the initial electron distribution is considered, the zeros of the dielectric function show the plasma to be stable if (eE/meω0v0) ≤ (2/3√3), ω0 > ωp, where v0 is the half-width of the distribution, ω0 and E are the field frequency and intensity, respectively.
Unstable Transverse Waves in a Plasma with Anisotropic Ion Distribution
Authors: Wu Ching-Sheng
Published: December 2004

The unstable transverse waves in an anisotropic multicomponent plasma are studied. Stability criteria are first established, and then it is shown that the anisotropic ion distribution may result in instabilities even if the electrons have isotropic distribution.
Differential Approximation for the Flux of Thermal Radiation
Authors: Helliwell J. B.
Published: December 2004

A differential approximation for the forward and backward radiative flux components is developed for three-dimensional flows, and simple forms are presented appropriate to models with planar, cylindrical, or spherical symmetry.
Experimentally Measured Velocity Distribution in the Plasma Stream of a Pulsed Coaxial Accelerator
Authors: Karras T. W. , Gorowitz B. , Gloersen P.
Published: December 2004

Measurements of the ion velocity distribution in a pulsed plasma stream have been performed. Agreement was found with the average velocity as computed from momentum transfer and mass flow measurements.
Turbulent Magnetohydrodynamic Channel Flow
Authors: Tennekes H.
Published: December 2004

An analogy appears to exist between turbulent magnetohydrodynamic channel flow at high Reynolds numbers and moderate Hartmann numbers on one hand, and turbulent boundary-layer flow with suction on the other. Skin-friction calculations confirm the existence of the analogy.
Identification of a SulP-type bicarbonate transporter in marine cyanobacteria
Authors: Price G. Dean , Woodger Fiona J. , Badger Murray R. , Howitt Susan M. , Tucker Loraine
Published: December 2004

Cyanobacteria possess a highly effective CO
2
-concentrating mechanism that elevates CO
2
concentrations around the primary carboxylase, Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase). This CO
2
-concentrating mechanism incorporates light-dependent, active uptake systems for CO
2
and HCO
–
3
. Through mutant studies in a coastal marine cyanobacterium,
Synechococcus
sp. strain PCC7002, we identified
bicA
as a gene that encodes a class of HCO
–
3
transporter with relatively low transport affinity, but high flux rate. BicA is widely represented in genomes of oceanic cyanobacteria and belongs to a large family of eukaryotic and prokaryotic transporters presently annotated as sulfate transporters or permeases in many bacteria (SulP family). Further gain-of-function experiments in the freshwater cyanobacterium
Synechococcus
PCC7942 revealed that
bicA
expression alone is sufficient to confer a Na
+
-dependent,

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\usepackage{wasysym}
\usepackage{amsfonts}
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\begin{equation*}{\mathrm{HCO}}_{3}^{-}\end{equation*}\end{document}

uptake activity. We identified and characterized three cyanobacterial BicA transporters in this manner, including one from the ecologically important oceanic strain,
Synechococcus
WH8102. This study presents functional data concerning prokaryotic members of the SulP transporter family and represents a previously uncharacterized transport function for the family. The discovery of BicA has significant implications for understanding the important contribution of oceanic strains of cyanobacteria to global CO
2
sequestration processes.
Xe NMR lineshapes in channels of peptide molecular crystals
Authors: Moudrakovski Igor , Soldatov Dmitriy V. , Ripmeester John A. , Sears Devin N. , Jameson Cynthia J.
Published: December 2004

To further an understanding of the nature of information available from Xe chemical shifts in cavities in biological systems, it would be advantageous to start with Xe in regular nanochannels that have well known ordered structures built from amino acid units. In this paper, we report the experimental observation of Xe NMR lineshapes in peptide channels, specifically the self-assembled nanochannels of the dipeptide
l
-Val-
l
-Ala and its retroanalog
l
-Ala-
l
-Val in the crystalline state. We carry out grand canonical Monte Carlo simulations of Xe in these channels to provide a physical understanding of the observed Xe lineshapes in these two systems.
Validation: The New Challenge for Pathology
Authors: Cardiff Robert D. , Rosner Andrea , Hogarth Michael A. , Galvez Jose J. , Borowsky Alexander D. , Gregg Jeffrey P.
Published: December 2004

Modern pathologists have been challenged to “validate” mouse models of human cancer. Validation requires matching of morphological attributes of the model to human disease. Computers can assist in the validation process. However, adequate controlled, computer-readable vocabularies that can match terms do not currently exist in mouse pathology. Further, current standard diagnostic terminologies do not include the new concepts discussed here such as pathway pathology and mammary intraepithelial neoplasia. The terminologies must be revised and improved to meet the challenge. Human medicine has traditionally used “guilt-by-association” to validate interpretations of disease. Experimental pathology uses experimental verification exemplified by “test-by-transplantation.” Genetically Engineered Mice (GEM) develop unique tumor phenotypes bringing new structural-functional insights and reevaluation of concepts. Novel GEM-related tumors appear in all organ systems but mouse models of human breast cancer are prototypes. For example, mammary tumors induced by Mouse Mammary Tumor Virus (MMTV), chemical, radiation or other carcinogenic stimuli have limited phenotypes. These “spontaneous” or induced mammary tumors have never resembled human breast cancers. GEM tumors created with genes associated with human cancer are strikingly different. GEM tumors have unique histological phenotypes. Depending on the genes, the tumors may: 1) resemble MMTV-induced tumors, 2) display “signature” phenotypes, and 3) mimic human breast cancers. The phenotypes can be placed into structural and functional clusters with shared characteristics leading to the concepts of Pathway Pathology: tumor phenotype reflects the genotype.
Genetic Variation and Exposure Related Risk Estimation: Will Toxicology Enter a New Era? DNA Repair and Cancer as a Paradigm
Authors: Mohrenweiser Harvey W.
Published: December 2004

With the vast technological and informational resources increasingly available from investments in “genomics,” toxicology and much of biological science, is faced with previously undreamed of opportunities and equally daunting challenges. The ability to generate the large quantities of data becoming routinely available could not be imagined a decade ago. The complexities of data analysis are increasingly the rate-limiting element in scientific advances. The expectations that these large scientific investments will reduce the incidence of human disease and improve health are very high. An emphasis on genetic variation and Toxicogenetics is expected to yield risk estimates for specific rather than average individuals and individuals with varied lifestyles and complex patterns of exposure. Examples from studies of polymorphic variation in DNA repair genes in the healthy population and cancer risk highlight the complexity and challenges of incorporating genetic variation into quantitative estimates of risk associated with environmentally relevant exposures. Similar issues exist in selecting the animal models most appropriate for predicting human risk from environmental exposures to toxic agents.
Risk Assessment in the Genomic Era
Authors: Cohen Samuel M.
Published: December 2004

The sequencing of the human and mouse genomes, and soon that of the rat, offers a foundation to evaluate biological phenomena, including toxicologic effects. Numerous tools are being developed to evaluate aspects of biology based on the DNA sequence. These tools can be utilized to evaluate absorption, distribution, metabolism and excretion, and effects of the toxicologically active product on the target organ. The genes involved can be broadly categorized as those affecting susceptibility to a toxicologic effect and those that are involved in the biologic response. For risk assessment to be performed in a rational manner, fundamental mechanisms of toxicologic processes must be ascertained. Based on successes already achieved, such as development of transgenic and knockout mouse strains, the application of aspects of the genomics revolution could be useful in developing a better understanding of mechanisms, and possibly in identifying specific markers of responses. In addition, genomics are likely to be useful in translating effects between species. However, genomics are being portrayed as the ultimate solution to all of toxicology. This is hardly the case. Basic chemistry, biochemistry, toxicokinetics, pharmacology, and pathology will continue to be needed in the overall weight of evidence approach to risk assessment. Genomics are likely to be of limited usefulness in predicting individual, in contrast to population susceptibility to various toxicological responses. Concordance of various diseases in identical twins, for example, different cancers, is rarely greater than 20% over the lifetime of these individuals. Similarly, genomics are likely to be of limited usefulness in screening for toxicologic end points. As with other tools of biology, those to be developed based on the genome are likely to provide greater usefulness in dissecting the mechanistic processes involved and defining the basis for susceptibility.
Regular Consumption of a Flavanol‐rich Chocolate can Improve Oxidant Stress in Young Soccer Players
Authors: Fraga Cesar G. , Actis-Goretta Lucas , Ottaviani Javier I. , Carrasquedo Fernando , Lotito Silvina B. , Lazarus Sheryl , Schmitz Harold H. , Keen Carl L.
Published: December 2004

The consumption of a diet rich in certain flavonoids, including the flavanol
sub‐class, has been associated with a reduced risk for vascular disease. We
evaluated the effects of the regular consumption (14 d) of a flavanol‐containing
milk chocolate (FCMC) or cocoa butter chocolate (CBC) on variables related to
vascular disease risk, oxidative stress and physical activity. Twenty‐eight free‐living,
young (18–20 years old) male soccer players consumed daily 105 g of FCMC
(168 mg of flavanols) or CBC (<5 mg of flavanols), as part of their normal diet.
The consumption of FCMC was significantly associated with a decrease in diastolic
blood pressure (‐5 mm Hg), mean blood pressure (‐5 mm Hg), plasma cholesterol
(‐11%), LDL‐cholesterol (‐15%), malondialdehyde (‐12%), urate (‐11%) and lactate
dehydrogenase (LDH) activity (‐11%), and an increase in vitamin E/cholesterol
(+12%). No relevant changes in these variables were associated with CBC
consumption. No changes in the plasma levels of (‐)‐epicatechin were observed
following analysis of fasting blood samples. In conclusion, FCMC consumption was
associated with changes in several variables often associated with cardiovascular
health and oxidant stress. The presence of significant quantities of
flavanols in FCMC is likely to have been one of the contributing factors to these results.
Remaking Civic Formation: towards a learning citizen?
Authors: Seddon Terri
Published: December 2004

This paper uses three examples of educational innovation emerging in the contemporary context of market-liberal reform as a focus for exploring the patterns and possibilities of civic formation. The first part of the paper contextualises contemporary civic formation within the long
historic struggle between capitalism and democracy, highlighting the way citizen learning is being reconfigured as markets and state are mediated by community interests. The last section attempts to draw out the key features of this community-based citizen learning and its implications for
citizen learning and action. This discussion provides a basis for clarifying the kind of civic and citizenship education that is needed to take community-based learning beyond localism towards formal civic engagement that can sustain and protect democracy. The idea of a learning citizen
is suggested as a way of conceptualising and acknowledging the contradictions within this citizenship agenda that holds the imperatives of lifelong learning in tension with the imperatives of educating citizen.
Race, Social Cohesion and the Changing Politics of Citizenship
Authors: Shukra Kalbir , Back Les , Keith Michael , Khan Azra , Solomos John
Published: December 2004

The relationship between race, social cohesion and citizenship has become an important issue in recent political and policy debates. In this paper these questions are explored in the context of the changing forms of ethnic minority political engagement and participation that have evolved
in the past two decades. We suggest that there are growing tensions in policy debates about the boundaries and limits of multicultural policies, particularly focused around the issue of social cohesion.
Building a Civic Culture Post-Conflict
Authors: Davies Lynn
Published: December 2004

This paper examines the role of education in (re)constructing civil society in societies emerging from conflict or violence. After examining the nature of civil society and its importance for democracy and peace, the paper looks at three areas: legal education (including human rights
education); information, media and the public space; and citizenship education (exploring nationalism, democracy and accountability). It aims to dispel any romanticised mythology about the possibilities of civic regeneration, particularly if this means returning to a nationalistic, exclusionary
or heroic past. The 'new normality' should be active citizens who will challenge social injustice, corruption or aggression; this is argued to apply to countries who are the instigators of international conflict as well as those traditionally labelled conflict or post-conflict.
Education for the Good Society: the integrity of academic practice
Authors: Nixon Jon
Published: December 2004

This paper argues that universities need to reclaim a public and inclusive language for education that reflects the moral ends and purposes of academic practice. It claims that there are certain moral goods implicit in the activities—of research, scholarship and teaching—that
comprise such practice; and it defines these goods in terms of virtuous dispositions towards truthfulness, respect and authenticity. The moral conditions of academic reconstruction necessarily include a commitment by academic practitioners to the development, in themselves and others, to these
goods of learning.
Anti‐laminin‐1 Autoantibodies, Pregnancy Loss and Endometriosis
Authors: Inagaki Junko , Kondo Akane , Lopez Luis R. , Shoenfeld Yehuda , Matsuura Eiji
Published: December 2004

Laminin‐1 is a major component and multifunctional glycoprotein of basement
membranes that consists of three different subunits, α1, β1 and γ1 chains. It is the
earliest synthesized network‐forming protein during embryogenesis and plays
an important role in embryonic development, embryonic implantation and
placentation. We have recently shown that IgG anti‐laminin‐1 antibodies were
significantly associated with recurrent first‐trimester miscarriages and with
subsequent pregnancy outcome. Interestingly, these antibodies were also observed
in patients with endometriosis‐associated infertility but not in patients with other
causes of infertility, including tubal factors, hormonal and uterine abnormalities.
Laminin‐α1, ‐β1 and ‐γ1 mRNAs have been detected in 90% of endometriotic lesions
and all laminin‐α1, ‐β1 and ‐γ1 chains were localized in the basement membranes of
glandular epithelium in endometriotic peritoneal lesions. Western blot analysis
showed that anti‐laminin‐1 antibodies from those patients reacted with all
laminin‐1′s chains. ELISA also confirmed that one of the target epitopes for these
antibodies was located in a particular region of the laminin‐1 molecule, i.e. the
carboxyl‐terminal globular G domain of α1 chain. IgM monoclonal anti‐laminin‐1
autoantibody, that we recently established, also recognized the G domain.
Anti‐laminin‐1 antibodies from mice immunized with –mouse— laminin‐1, caused
a higher fetal resorption rate with lower embryonic and placental weights. Thus,
anti‐laminin‐1 antibodies may be important in development of autoimmune‐mediated
reproductive failures and the
assessment of the antibodies may provide a novel non‐invasive diagnosis of
endometriosis.
On the Mechanisms of the Protective Effect of Infections on Type 1 Diabetes
Authors: Feillet Hélène , Bach Jean-François
Published: December 2004

The incidence of type 1 diabetes (T1D) shows a worrying tendency for a steady increase in Western countries. Along the line of the hygiene hypothesis, evidence accumulates to suggest that this increase is explained by the decrease of infections due to improved hygiene and medical care. This article presents a review of epidemiological data and of the main putative underlying cellular and molecular mechanisms.
Arend Lijphart's Dimensions of Democracy: Logical Connections and Institutional Design
Authors: Taagepera Rein
Published: December 2004

Lijphart's (1999) analysis maps countries along two dimensions of democratic institutions: ‘executives-parties’ or ‘joint-power’, and ‘federal-unitary’ or ‘divided-power’. My ‘meta-study’ maps the methodology of Lijphart's mapping: the nature of indices (inputs or outputs), their logical interconnections, their susceptibility to institutional design (‘constitutional engineering’), and their suitability for expressing the intended underlying concepts. Strikingly, the joint-power indicators are highly correlated and mostly logically connected output measures, which are not susceptible to institutional design, while the opposite is true for the divided-power dimension. For this dimension most indices are expert estimates of inputs, marginally correlated, yet subject to institutional design, limited by size dependence. Surprisingly, the parliamentary-presidential aspect of institutional design does not affect the picture. The connection between cabinet life and the number of parties is even stronger than found by Lijphart. Interest groups and central bank independence fit his dimensions empirically but less so logically. In sum, institutional design may be more difficult than sometimes assumed, but offers hope.
Sex Differences in Political Knowledge in Britain
Authors: Frazer Elizabeth , Macdonald Kenneth
Published: December 2004

This paper analyses, and examines the interpretation of, sex differences in political knowledge as measured in the context of nationally representative British surveys. The paper discusses the construction and operationalisation of ‘knowledge’ measures in survey research. British survey research finds striking sex differences in scores on political knowledge items. The inclusion of contextual variables, and of interactions between sex and other relevant variables, attenuates but does not eliminate consistent sex differences.