bluuebunny/crossref_metadata_2025 huggingface dataset:
The diffraction of a planar detonation wave at an abrupt area change
Authors: Edwards D. H. , Thomas G. O. , Nettleton M. A.
Published: April 2006

Previous experimental work on the diffraction of a detonation wave at a large and abrupt area change in a tube, has shown that every system is characterized by a critical tube diameter at which quenching of the detonation occurs. Zeldovich, Kogarko & Simonov (1956) established that the critical tube diameter, for the oxy-acetylene system with varying dilution of nitrogen, lies between 500 and 700 times the one-dimensional induction zone length. Later, Mitrovanov & Soloukhin (1964) discovered that, for the same system, the critical diameter is 10 or 13 times the transverse wave spacing for a flat channel and cylindrical tube respectively. The two results are shown to be equivalent and are confirmed by further experiments in a 75 × 6 mm channel in which the flow is two-dimensional.

Smoked foil and schlieren records show that, for supercritical waves, re-ignition occurs at sites along the wedge formed by the head of the expansion from the diffracting aperture and criticality is attained when the site is located at the apex of the wedge. A universal feature of re-initiation, which is also observed in liquid and solid explosives, is the sudden appearance of a transverse detonation which sweeps through the compressed, but unreacted, gas of the dissociated shock-reaction zone regime; this is signalled by the appearance of fine triple-point writing on smoked-foil records.

A criterion for re-initiation is formulated by equating the critical velocity gradient which characterizes the decay of the wavefront in a cell, to that obtaining in the diffracted shock front at the head of the expansion fan; an expression for the latter is derived from Whitham's (1957) theory for non-reactive shocks. The prediction of the criterion is in good agreement with observation.
Measurements in subsonic and supersonic free jets using a laser velocimeter
Authors: Lau Jark C. , Morris Philip J. , Fisher Michael J.
Published: April 2006

Velocity measurements in a 51 mm diameter turbulent jet are presented. The measurement programme is conducted in two parts. The first part is devoted to the validation of laser velocimeter (LV) data. This consists of comparative measurements with the LV and a hot-wire anemometer. The second part consists of a survey of the jet flow field at Mach 0·28, 0·90, and 1·37 under ambient temperature conditions. Radial and centre-line distributions of the axial and radial, mean and fluctuating velocities are obtained. The distributions indicate a decrease in the spreading rate of the mixing layer with increasing Mach number and a corresponding lengthening of the potential core. The results further indicate that these two parameters vary with the square of the jet Mach number. Radial distributions collapse when plotted in terms of ση*, where σ = 10.7/(1 - 0.273 MJ2) and η* = (r − r0·5)/x. This is true for distributions in planes located as far downstream as two potential core lengths. The collapsed data of mean velocity can be approximated by a Görtler error function profile:
\[
U/U_J = 0.5[1-{\rm erf}(\sigma\eta^{*})].
\]
Centre-line distributions at various Mach numbers also collapse if plotted in terms of x/xc, xc being the potential core length. A general equation for the collapsed data of mean velocity is given by: U/UJ = 1 - exp{1.35/(1 - x/xc)}, for the range of Mach numbers 0·3-1·4, where xc = 4.2 + 1.1 MJ2.
The unsteady pressure field of a ducted impeller
Authors: Dang Dac Q. , Norrie D. H.
Published: April 2006

Analyses based on a three-dimensional vortex-filament model are presented for the unsteady pressure field generated by a ducted propeller. An oscillating part is identified in the kernels and absolute terms of the governing equations for the harmonic components, allowing two methods to be developed for the solution of the higher harmonics. The first method is exact and is applicable to ducted propellers with practical configurations (small chord-to-diameter ratio) while the second is approximate but more suitable for ducted systems with large chord-to-diameter ratios. The second method was applied to a configuration for which experimental data were available and good agreement was obtained for pressure harmonic amplitudes downstream of the propeller and for phase angles upstream of the propeller.

Special consideration was given to the Kutta-Joukowski condition at the duct trailing edge and a general constraint developed for the doubly coupled governing integral equations.
Mechanisms of decay of laminar and turbulent vortices
Authors: Uberoi Mahinder S.
Published: April 2006

The dynamics of an infinitely long one-dimensional vortex and a swirl are compared with the dynamics of a semi-infinitely long trailing vortex and trailing swirl. With increasing distance, the change in the axial velocity difference between the core of the trailing vortex and the surrounding region causes radial convection and some associated axial convection of angular momentum. In laminar or turbulent trailing vortices, we show that under most conditions of interest this is the dominant mechanism for the decrease in the velocities of swirl in the core and corresponding growth of the core. On the basis of theoretical considerations and experimental observations, we show that the axial velocity difference between the core of the trailing vortex and the surrounding region is necessary for the sustenance of turbulence in the vortex core. A theory of the turbulent trailing vortex is developed on the basis of these mechanisms and the results are compared with our experimental observations.
Note on Gill's solution for free convection in a vertical enclosure
Authors: Bejan Adrian
Published: April 2006

This paper develops an alternative approach to evaluating the arbitrary constants found in Gill's solution for the boundary-layer free-convection regime in a vertical rectangular enclosure. The new method consists of calculating the net upward flow of energy through the enclosure and setting it equal to zero near the top and bottom boundaries of the cavity. The present method takes into account the impermeable and adiabatic properties of the horizontal end walls. The overall Nusselt number derived on this new basis is shown to agree well with available experimental and numerical heat-transfer correlations.
Waves in parallel or swirling stratified shear flows
Authors: Leibovich S.
Published: April 2006

The dispersion relations for infinitesimal internal gravity waves (A) and axisymmetric waves in swirling streams (B) are considered. In both cases the mainstream may be sheared and density stratified in the transverse (vertical in case A, radial in case B) direction. The following results are proved for either case: If the maximum speed Wmax (or minimum speed Wmin) (in a meridian plane in case B) of the mainstream occurs at an interior point in the fluid, then the phase speed of any mode takes all values from the Wmax (or Wmin) to +∞ ( —∞) as the overall Richardson number λ2 varies from 0 to ∞. If Wmax(Wmin) is attained at a boundary point with finite rate of strain, there is a positive non-zero critical Richardson number below which one or both branches of the dispersion relation terminate. These results employ variational methods and correct erroneous results concerning problem B stated in Chandrasekhar's treatise on hydrodynamic stability. Furthermore, bounds are given on the group velocity for both branches of the dispersion relation. From these bounds it is shown that in the absence of reversals of the mainstream (Wmin > 0) upstream propagation of wave energy is impossible whenever upstream propagation of constant phase surfaces is impossible.
On the flow around a buoyant cylinder within a rapidly rotating horizontal cylindrical container
Authors: Gans Roger F.
Published: April 2006

Steady flow in a cylinder of finite length rotating rapidly at right angles to the earth's gravity and containing a rigid cylindrical float is found under the assumption of small viscosity. The float is modelled by a ‘rigid free surface'. The major new result is a prediction of the rotation rate of the interface, which differs by a factor of O(E1/4) from those given by Greenspan (1976) and Wood (1977) for a rigid interface in an infinitely long cylinder. The difference is accounted for by the appearance of Stewartson layers on the inner boundary in the finite case. The result is supported by an experiment of my own, and is not in conflict with the experimental results given by Greenspan.

Some additional experimental observations are reported: a comparison of free and rigid surface rotation rates; and a brief description of the spin-up from rest.
Thermally-induced extrudate swell
Authors: Phuoc H. B. , Tanner R. I.
Published: April 2006

In many polymer processing applications, the generation of heat by viscous losses in the flowing molten polymer is highly significant. The heating reduces the viscosity of the melt sharply and the flow patterns are different from the isothermal case. In this paper, a finite element scheme based on the Galerkin method is developed and is used to explore the effects of thermally induced property changes in extrusion.

In the program we solve simultaneously for the flow and temperature fields at each iteration. To check the program for accuracy and correctness, some simple problems were first attempted. A solution for viscous heating in Poiseuille flow was used to check the variable-viscosity part of the program. The crucial convection (‘radiation’) boundary condition was checked using the solution for cooling of a moving rod. Finally, the swelling of extruded jets with self-heating was investigated. A new phenomenon, thermal extrudate swell, was thereby discovered. We have found extrudate expansions up to 70% of the die diameter in a Newtonian fluid with thermal properties similar to those of low density polyethylene. It is clear that this phenomenon will affect many experimental interpretations of extrudate swelling.
A mathematical model for fluid flow in a weld pool at high currents
Authors: Atthey D. R.
Published: April 2006

In order to determine the heat transfer inside a TIG (tungsten/inert gas) weld pool, it is necessary to have a good understanding of the flow patterns of the liquid metal. The principal force driving the fluid motion is the electromagnetic j × B force due to the current from the welding arc and its self-magnetic field. In this paper we consider the flow of a viscous incompressible conducting fluid in a hemispherical container due to various distributions of the electric current. The problem is posed as a time-dependent problem and is solved numerically using the Du Fort–Frankel leap-frog method. Results are presented for currents of 100 A flowing through the weld pool. This is a typical current for TIG welding, and corresponds to a Reynolds number in the range 200 < Re < 600. Previous solutions of the problem were restricted to low Reynolds numbers, i.e. low currents.
Some relations for bodies in a canal, with an application to wave-power absorption
Authors: Srokosz M. A.
Published: April 2006

By the use of Green's theorem, relations are derived for the interaction of regular waves with a body in a canal. These relations are then applied to the problem of wave-power absorption by a body in a canal; this being taken as a model of an infinite row of wave-power absorbers. Two particular shapes of wave-power absorber are studied by use of thin-ship approximation. It is shown that the efficiency of power absorption by. a body in a canal may be much reduced when there is more than one travelling wave mode present in the canal.
Gravity currents entering a two-layer fluid
Authors: Holyer Judith Y. , Huppert Herbert E.
Published: April 2006

This paper presents a study of steady gravity currents entering a two-layer system, with the current travelling either along the boundary to form a boundary current, or between the two different layers to form an intrusion. It is shown that, at the front of an intrusion, the streamlines meet at angles of 120° at a stagnation point. For an energy-conserving current the volume inflow rate to the current, the velocity of propagation and the downstream depths are determined. In contrast to the pioneering study of Benjamin (1968), it is found that the depth of the current is not always uniquely determined and it is necessary to use some principle additional to the conservation relationships to determine which solution occurs. An appropriate principle is obtained by considering dissipative currents. In general, if the volume inflow rate to a current is prescribed, the current loses energy in order to maintain a momentum balance. We thus suggest the criterion that the energy dissipation is a maximum for a fixed volume inflow rate. It is postulated that the energy which is lost will go to form a stationary wave train behind the current. A nonlinear calculation is carried out to determine the amplitude and wavelength of these waves for intrusions. Such waves have been observed on intrusions in laboratory experiments and the results of the calculation are found to agree well with the experiments. Similar waves have not been observed on boundary currents because the resulting waves have too much energy and break.
On the algebraic decay of disturbances in a stratified linear shear flow
Authors: Brown S. N. , Stewartson K.
Published: April 2006

In this note we confirm the time dependence of the decay of disturbances in a stratified linear shear flow found by Eliassen, Høiland & Riis (1953) and by Booker & Bretherton (1967). The result differs from those of Case (1960b) and of Chimonas (1979) which are incorrect.
Vertical slender jets
Authors: Geer James F. , Strikwerda John C.
Published: April 2006

The shape of a vertical slender jet of fluid falling steadily under the force of gravity is studied. The problem is formulated as a nonlinear free boundary-value problem for the potential. Surface tension effects are neglected. The use of perturbation expansions results in a system of equations that can be solved by an efficient numerical procedure. Computations were made for jets issuing from orifices in various shapes including an ellipse, a rectangle, and an equilateral triangle. Computational results are presented illustrating the propagation of discontinuities and the formation of thin sheets of fluid.
Jet diffusion from a circular nozzle above a solid plane
Authors: Davis M. R. , Winarto H.
Published: April 2006

The decay of a jet discharging from a circular nozzle parallel to and displaced from a solid surface is investigated under conditions where the transitional process from circular-jet flow to oblate wall-jet flow begins in the initial, transition or self-preserving regions of the original jet. The influence of displacement of the nozzle from the plane on the developed three-dimensional wall jet downstream is demonstrated and it is found that the transitional interaction with the plane is more extended when the plane interacts first in the initial zone of the circular jet. Measurements of turbulence and Reynolds stress show the transverse mixing parallel to the plane to exceed that perpendicular to the plane, and are generally consistent with the spreading rates in these two directions, the ratio of which approaches 8·5 at large distances from the nozzle. It is shown that the interaction between the plane and jet involves a relatively large-scale coherent motion in which components of velocity directed towards or away from the surface are associated with outflow or inflow along the surface. This motion is more extended in the direction parallel to the surface and provides a mechanism for the increases in mixing rate in the direction parallel to the plane.
Heat transfer to a slowly moving fluid from a dilute fixed bed of heated spheres
Authors: Acrivos A. , Hinch E. J. , Jeffrey D. J.
Published: April 2006

Using the method of averaged equations, we examine the difference in temperature between the bulk and fixed heated spherical particles under conditions in which ϕ the volume fraction of the particles and ε the Peclet number of the flow past the particles are both small. If ϕ [Lt ] ε2 the particles are effectively isolated, and so their excess temperature has an O(ε) correction to the pure conduction estimate. On the other hand if ϕ [Gt ] ε2, the bulk heating is of sufficient magnitude to produce a significant temperature gradient throughout the fixed bed. This temperature gradient leads to an O(ϕ½) correction to the pure conduction estimate of the excess temperature of the particles, and the correction depends on the details of the flow even though its magnitude is independent of ε. A study of the leading-order terms when ϕ and ε2 are of the same magnitude finds that the two small effects are not simply additive.
Nonlinear oscillations of non-spherical cavitation bubbles in acoustic fields
Authors: Hall P. , Seminara G.
Published: April 2006

The nonlinear stability of gas bubbles in acoustic fields is studied using a multiple-scale type of expansion. In particular the development of a subharmonic or a synchronous perturbation to the flow is investigated. It is shown when an equilibrium non-spherical shape oscillation of a bubble is stable. If the amplitude of the sound field is ε then it is shown that subharmonic perturbations of order ε½ can exist and be stable. Furthermore synchronous perturbations of order ε can exist and be stable. It is shown that synchronous perturbations, unlike the subharmonic case where the bifurcation is symmetric, bifurcate transcritically when the driving frequency is varied and also undergo secondary bifurcations. It is further shown that, in certain cases, the latter properties of the synchronous modes cause the flow to exhibit a hysteresis phenomenon when the driving frequency is varied.
Nonlinear Rayleigh–Bénard convection between poorly conducting boundaries
Authors: Chapman C. J. , Proctor M. R. E.
Published: April 2006

The convective instability of a layer of fluid heated from below is studied on the assumption that the flux of heat through the boundaries is unaffected by the motion in the layer. It is shown that when the heat flux is above the critical value for the onset of convection, motion takes place on a horizontal scale much greater than the layer depth. Following Childress & Spiegel (1980) the disparity of scales is exploited in an expansion scheme that results in a nonlinear evolution equation for the leading-order temperature perturbation. This equation which does not depend on the vertical co-ordinate, is solved analytically where possible and numerically where necessary; most attention is concentrated on solutions representing two-dimensional rolls. It is found that for any given heat flux a continuum of steady solutions is possible for all wave numbers smaller than a given cut off. Stability analysis reveals, however, that each mode is unstable to one of longer wavelength than itself, so that any long box will eventually contain a single roll, even though the most rapidly growing mode on linear theory has much shorter wavelength.
The interaction between stirring and osmosis. Part 1
Authors: Pedley T. J.
Published: April 2006

When pure solvent is separated from a solution of non-zero concentration Cb by a semi-permeable membrane, permeable to solvent (water) but not to solute, water flows osmotically across the membrane towards the solution. Its velocity J is given by J = PΔC, where P is a constant and ΔC is the concentration difference across the membrane. Because the osmotic flow advects solute away from the membrane, ΔC is usually less than Cb, by a factor γ which depends on the thickness of and flow in a concentration boundary layer. In this paper the layer is analysed on the assumption that the stirring motions in the bulk solution, which counter the osmotic advection, can be represented as two-dimensional stagnation-point flow. The steady-state results are compared with those of the standard physiological model in which the layer has a given thickness δ and the osmotic advection is countered only by diffusion. It turns out that the standard theory, although mechanistically inadequate, accurately predicts the value of γ over a wide range of values of the governing parameter β = PCbδ/D (where D is the solute diffusivity) if δ is given by
\[
\delta = 1.59\bigg(\frac{D}{\nu}\bigg)^{\frac{1}{3}}\bigg(\frac{\nu}{\alpha}\bigg)^{\frac{1}{2}},
\]
where ν is the kinematic viscosity of the fluid and α is the stirring parameter. The final approach to the steady state is also analysed, and it is shown to be achieved in a time scale (D/ν)1/3/αk′ where k′ is a dimensionless number whose dependence on β is computed. Moreover, if β exceeds a certain critical value (≈ 10), the approach to the steady state is not monotonic but takes the form of a damped oscillation (in practice, however, β is unlikely to rise significantly above 1). The theory is extended to the case where the solute concentration is non-zero on both sides of the membrane and in that case it is shown that J is bounded as β → ∞.
On the visual growth of a turbulent mixing layer
Authors: Jimenez J.
Published: April 2006

Two models are discussed to account for the motion of the concentration interface in turbulent mixing layers. In the first one the interface is treated as a vortex sheet and its roll-up is studied. It is argued that this situation represents only the first stages of layer growth and another model is studied in detail in which a row of vortex cores entrains an essentially passive concentration interface with no vorticity. Both models give values of the spreading rate in approximate agreement with observations, and their relation is discussed.
Internal structure of copper(II)-phthalocyanine thin films on SiO2∕Si substrates investigated by grazing incidence x-ray reflectometry
Authors: Brieva A. C. , Jenkins T. E. , Jones D. G. , Strössner F. , Evans D. A. , Clark G. F.
Published: April 2006

The internal structure of copper(II)-phthalocyanine (CuPc) thin films grown on SiO2∕Si by organic molecular beam deposition has been studied by grazing incidence x-ray reflectometry (GIXR) and atomic force microscopy. The electronic density profile is consistent with a structure formed by successive monolayers of molecules in the α form with the b axis lying in the substrate surface plane. The authors present an electronic density profile model of CuPc films grown on SiO2∕Si. The excellent agreement between the model and experimental data allows postdeposition monitoring of the internal structure of the CuPc films with the nondestructive GIXR technique, providing a tool for accurate control of CuPc growth on silicon-based substrates. In addition, since the experiments have been carried out ex situ, they show that these structures can endure ambient conditions.
Isotropic-nematic phase transition of nonaqueous suspensions of natural clay rods
Authors: Zhang Z. X. , van Duijneveldt Jeroen S.
Published: April 2006

A novel model system for studying the behavior of hard colloidal rods is presented, consisting of sterically stabilized particles of natural sepiolite clay. Electron microscopy and scattering results confirmed that the organophilic clay particles were individual, rigid rods when dispersed in organic solvents. With a length-to-diameter ratio of approximately 27, the particles showed nematic ordering for volume fractions ϕ>0.06. Polarizing microscopy revealed that the phase separation process involved nucleation, growth, and coalescence of nematic domains. The phase volumes and particle concentrations in the coexisting phases were determined. The dependence of these quantities on the total concentration of the suspension agrees well with Onsager's [Ann. N. Y. Acad. Sci. 51, 627 (1949)] isotropic-nematic phase transition theory extended to bidisperse and polydisperse rod systems, and with previous experimental results for rigid rodlike particles. Particle size distributions were obtained by analyzing transmission electron microscopy images. A significant fractionation with respect to rod length (but not diameter) was observed in the coexisting isotropic and nematic phases. The relative polydispersity of both daughter phases was distinctly smaller than that of the parent suspension. The phase behavior of these daughter fractions agrees well with the predictions for hard spherocylinders of corresponding aspect ratios. An isotropic-nematic-nematic phase equilibrium was seen to develop in phase separated samples after 1month standing and is ascribed to the effect of polydispersity and possibly gravity. The second nematic phase appearing is dominated by very long rods.
Perpendicular magnetic anisotropy in chemically disordered FePd–FeV(100) alloy thin films
Authors: Clavero C. , García-Martín J. M. , Armelles G. , Cebollada A. , Huttel Y. , Estradé S. , Arbiol J. , Peiró F. , Balcells Ll.
Published: April 2006

We find that the use of V(100) buffer layers on MgO(001) substrates for the epitaxy of FePd binary alloys yields to the formation at intermediate and high deposition temperatures of a FePd–FeV mixed phase due to strong V diffusion accompanied by a loss of layer continuity and strong increase of its mosaic spread. Contrary to what is usually found in this kind of systems, these mixed phase structures exhibit perpendicular magnetic anisotropy (PMA) which is not correlated with the presence of chemical order, almost totally absent in all the fabricated structures, even at deposition temperatures where it is usually obtained with other buffer layers. Thus the observed PMA can be ascribed to the V interdiffusion and the formation of a FeV alloy, being the global sample saturation magnetization also reduced.
Optical anisotropy and strain evolution of GaAs surfaces at the onset of the formation of InAs quantum dots
Authors: Chen Y. H. , Jin P. , Ye X. L. , Xu B. , Wang Z. G. , Yang Z.
Published: April 2006

By using reflectance difference spectroscopy we have studied the in-plane optical anisotropy of GaAs surfaces covered by ultrathin InAs layers. The strain evolution of the GaAs surface with the InAs deposition thickness can be obtained. It is found that the optical anisotropy and the surface tensile strain attain maximum values at the onset of the formation of InAs quantum dots (QDs) and then decrease rapidly as more InAs QDs are formed with the increase of InAs deposition. The origin of the optical anisotropy has been discussed.
Interface formation during molecular beam epitaxial growth of neodymium oxide on silicon
Authors: Fissel A. , Elassar Z. , Kirfel O. , Bugiel E. , Czernohorsky M. , Osten H. J.
Published: April 2006

The Si/dielectric interface properties influence device performance significantly. Often the interface is not stable and changes during and/or after the growth. For a better understanding of the interface and layer formation processes of Nd2O3 on Si(001), as an example for the lanthanide oxides, well-defined experimental studies by reflection high-energy diffraction and x-ray photoelectron spectroscopy were performed under ultraclean ultrahigh vacuum conditions of molecular beam epitaxy. Complementary investigations were performed by transmission electron microscopy. We found that Nd2O3 is a candidate for replacing silicon dioxide as gate dielectric in future Si devices with suitable band gap and offset with respect to silicon. However, under ultrahigh vacuum conditions, silicide formation occurs in the initial stage of growth, which can result in large silicide inclusions and hole formation during further growth. This effect can be completely prevented by modifying the oxygen partial pressure during the interface formation and layer growth.
Optimization of spin-filtering properties in diluted magnetic semiconductor heterostructures
Authors: Radovanović J. , Milanović V. , Ikonić Z. , Indjin D.
Published: April 2006

We have performed structural parameter optimizations of asymmetric ZnSe∕Zn1−xMnxSe multilayer structures in magnetic and electric fields to maximize the spin polarization of the electron tunnel current. The optimization procedure was carried out by simulated annealing, with target functions set to obtain the best possible spin-polarization properties within the chosen range of bias voltages. The performance of the optimized structure is predicted to exceed that of the existing spin-diode designs.
Comparison of methods for estimating continuous distributions of relaxation times
Authors: Tuncer Enis , Macdonald J. Ross
Published: April 2006

The nonparametric estimation of the distribution of relaxation-time approach is not as frequently used in the analysis of dispersed response of dielectric or conductive materials as are other immittance data analysis methods based on parametric curve fitting techniques. Nevertheless, such distributions can yield important information about the physical processes present in measured material. In this paper, we apply two quite different numerical inversion methods to estimate the distribution of relaxation times for glassy Li0.5La0.5TiO3 dielectric frequency-response data at 225K. Both methods yield unique distributions that agree very closely with the actual exact one accurately calculated from the corrected bulk-dispersion Kohlrausch model established independently by means of parametric data fit using the corrected modulus formalism method. The obtained distributions are also greatly superior to those estimated using approximate function equations given in the literature.
Enhancement effect of germanium on oxygen precipitation in Czochralski silicon
Authors: Chen Jiahe , Yang Deren , Li Hong , Ma Xiangyang , Que Duanlin
Published: April 2006

Oxygen precipitation in germanium (Ge)-doped Czochralski (CZ) silicon has been investigated through a series of isothermal anneals at temperatures ranging from 550to950°C. It is found that the nucleation of oxygen precipitates can be enhanced in a wide temperature range and the onset temperature for precipitate nucleation can be increased by the germanium doping. Furthermore, it is also revealed that the oxygen precipitates with a higher density and smaller sizes can be formed in germanium-doped CZ silicon in comparison with those in conventional CZ silicon. These two phenomena are ascribed to the reduction in the critical radius for oxygen precipitation and the increase in the concentration of heterogeneous nuclei due to the germanium doping.
Analysis of optothermionic refrigeration based on semiconductor heterojunction
Authors: Han Peng , Jin Kui-juan , Zhou Yueliang , Wang Xu , Ma Zhongshui , Ren Shang-Fen , Mal’shukov A. G. , Chao K. A.
Published: April 2006

We have examined the theory of optothermionic refrigeration combining the ideas of laser cooling and thermionic cooling [Mal’shukov and Chao, Phys. Rev. Lett. 86, 5570 (2001)] and its estimation on thermal energy extraction by using self-consistent calculations with the drift-diffusion model in this paper. Both the Auger and the Shockley-Read-Hall dissipation processes are considered. For GaAs∕AlGaAs systems with various impurity concentrations and different widths of quantum well, it is found that the optothermionic cooler can extract thermal energy at a rate as much as 10W∕cm2. The information to perform optothermionic refrigeration in real devices have also been provided.
Improved Wang-Landau sampling through the use of smoothed potential-energy surfaces
Authors: Nguyen Phuong H. , Mittag Emil , Torda Andrew E. , Stock Gerhard
Published: April 2006

A method is presented to improve the speed of convergence of Wang-Landau simulations as used to calculate the density of states of continuous systems. The density of states is first crudely estimated with calculations employing a smoothed potential-energy surface. This estimate is then used as a seed for subsequent Wang-Landau simulations using the original potential. The performance of the method is demonstrated by employing several simple models, including an analytically solvable harmonic system as well as a Gō model of a protein. For all systems considered, the seeded simulations were found to converge significantly faster and with higher accuracy than the standard Wang-Landau simulations.
Organic light-emitting transistors using concentric source/drain electrodes on a molecular adhesion layer
Authors: Santato Clara , Cicoira Fabio , Cosseddu Piero , Bonfiglio Annalisa , Bellutti Pierluigi , Muccini Michele , Zamboni Roberto , Rosei Federico , Mantoux Arnaud , Doppelt Pascal
Published: April 2006

Bottom-contact tetracene light-emitting transistors employing a mercaptosilane derivative self-assembled monolayer as adhesive between gold concentric interdigitated source/drain electrodes and SiO2 gate dielectric are described. Devices that employ the mercaptosilane adhesive have a higher mobility and electroluminescence compared to those employing a standard metallic adhesive. This is rationalized in terms of the large, well interconnected grains found in tetracene films deposited on substrates using the mercaptosilane adhesive. Our work represents a step forward in the understanding of physical processes at semiconductor/metal and semiconductor/dielectric interfaces in organic devices.
Interface sharpening in CoFeB magnetic tunnel junctions
Authors: Pym A. T. G. , Lamperti A. , Tanner B. K. , Dimopoulos T. , Rührig M. , Wecker J.
Published: April 2006

We report grazing incidence x-ray scattering evidence for sharpening of the interface between amorphous Co60Fe20B20 and AlOx during in situ annealing below the Co60Fe20B20 crystallization temperature. Enhancement of the interference fringe amplitude in the specular scatter and the absence of changes in the diffuse scatter indicate that the sharpening is not a reduction in topological roughness but a reduction in the width of the chemical composition profile across the interface. The temperature at which the sharpening occurs corresponds to that at which a maximum is found in the tunneling magnetoresistance of magnetic tunnel junctions.
Infrared induced red luminescence of Eu3+-doped polycrystalline LiNbO3
Authors: Hreniak D. , Strek W. , Speghini A. , Bettinelli M. , Boulon G. , Guyot Y.
Published: April 2006

Polycrystalline lithium niobate powders were prepared by the sol-gel method. Different grain sizes were obtained by controlling the annealing temperature. The Eu3+ ion was used as a luminescent probe of the nonlinear optical properties of the grains. Strong red emission deriving from Eu3+ ions was observed under pulsed infrared laser irradiation at 936.0nm due to absorption of the light produced in the second harmonic generation process. A measurable emission was observed only for grains having a size of the least 200nm, depending on the annealing temperature.
Efficient laser oscillation of Yb:Y3Al5O12 single crystal grown by temperature gradient technique
Authors: Dong Jun , Shirakawa Akira , Ueda Ken-ichi , Xu Jun , Deng Peizhen
Published: April 2006

Low-threshold and highly efficient continuous-wave laser performance of Yb:Y3Al5O12 (Yb:YAG) single crystal grown by a temperature gradient technique (TGT) was achieved at room temperature. The laser can be operated at 1030 and 1049nm by varying the transmission of the output coupler. Slope efficiencies of 57% and 68% at 1049 and 1030nm, respectively, were achieved for 10at.% Yb:YAG sample in continuous-wave laser-diode pumping. The effect of pump power on the laser emission spectrum of both wavelengths is addressed. The near-diffraction-limited beam quality for different laser cavities was achieved. The excellent laser performance indicates that TGT-grown Yb:YAG crystals have very good optical quality and can be potentially used in high-power solid-state lasers.
Successful steroid treatment of acquired idiopathic partial hypohidrosis
Authors: YORITAKA Asako , HISHIMA Tsunekazu , AKAGI Kumiko , KISHIDA Shuji
Published: April 2006

The pathogenesis of idiopathic‐acquired hypohidrosis remains unknown, and no specific causes have yet been established. We report a 34‐year‐old man with acquired idiopathic hypohidrosis successfully treated with prednisolone. The patient noticed heat intolerance and hypohidrosis of the pectoral and back during the summer. No systemic disease or neurological findings were identified. Eccrine sweat glands displayed infiltration by inflammatory cells, with immunoglobulin G and C3 deposition in the basement membrane. Steroid therapy improved the hypohidrosis. An immunological pathogenesis could be a major factor in idiopathic‐acquired hypohidrosis.
Pigmented coalescing papules on the dorsa of the hands: Pigmented colloid milium associated with exogenous ochronosis
Authors: GÖNÜL Müzeyyen , ÇAKMAK Seray Külcü , KILIÇ Arzu , GÜL Ülker , HEPER Aylin Okçu
Published: April 2006

Colloid milium is a rare cutaneous deposition disorder that frequently occurs in areas of chronic sun exposure such as the face, neck and backs of the hands and is characterized by multiple small, discrete, usually amber‐colored, dome‐shaped papules that cluster to form large plaques. A 50‐year‐old white woman with esophageal squamous cell carcinoma was referred to us with asymptomatic, slowly spreading lesions localized to the dorsa of her hands which had been present for 4 years. The condition was diagnosed histopathologically as pigmented colloid milium associated with exogenous ochronosis (EO). Colloid milium associated with EO is very rarely reported in the published work. We think that a possible interaction between sunlight and exposure to chemical fertilizers may have played a role in the pathogenesis of both of the disorders in our case.
Effects of Mycophenolic Acid on Inosine Monophosphate Dehydrogenase I and II mRNA Expression in White Blood Cells and Various Tissues in Sheep
Authors: Dzidic A. , Prgomet C. , Mohr A. , Meyer K. , Bauer J. , Meyer H. H. D. , Pfaffl M. W.
Published: April 2006

Mycophenolic acid (MPA) is a mycotoxin commonly found as Penicillium genus secondary metabolite in feedstuffs and silages. Feeding with MPA contaminated silages may modulate the immune system in the farm animals and can cause appetite lost, ketosis, paralysis and abortion. The aim of the present study was to characterize the long‐term MPA effect on both the inosine monophosphate dehydrogenase (IMPDH) isoforms I and II mRNA expression in white blood cells (WBC) and various tissue of healthy sheep. In treated animals 300 mg MPA/day/sheep was applied. In all investigated tissues the IMPDH I and II mRNA was abundant: WBC, spleen, thymus, ileum, jejunum, kidney, liver, pharyngeal and mesenterial lymph node. An efficiency‐corrected relative quantification of the IMPDH types I and II isoforms mRNA were performed by normalizing with the constant reference gene expression of β‐actin. High IMPDH I mRNA expression levels were seen in kidney > mesenterial lymph node > jejunum > spleen > pharyngeal lymph node. Medium and low abundance was found in ileum > WBC > liver > thymus. Type II mRNA was highly expressed in liver > thymus > jejunum. In pharyngeal lymph node > spleen > ileum > mesenterial lymph node > kidney > WBC medium to low IMPDH II mRNA concentrations were detected. Under MPA treatment the IMPDH I mRNA expression was not significantly regulated in WBC, only trends of down‐ and upregulation were observed. Surprisingly in jejunum an upregulation could be observed (P < 0.05). In pharyngeal lymph node a tendency to downregulation was shown. This may be due to frequent ruminant activities and frequent exposition of MPA to the pharyngeal lymph nodes. In contrast to type I mRNA expression, IMPDH II mRNA was significantly downregulated in ileum (3.4‐fold, P < 0.01) and tendencies in downregulation could be seen in jejunum (5.1‐fold, P = 0.14). In addition, significant downregulation of IMPDH II gene expression over the entire feeding experiment could be shown in WBC of MPA‐treated animals compared with untreated animals (P < 0.05). In conclusion, the recent study demonstrates that feeding sheep with MPA‐contaminated silage did not induce IMPDH I mRNA expression in various tissues and blood, except in jejunum, but has suppressive effects on IMPDH II mRNA expression in WBC and ileum.
Ophthalmoscopic Characteristics in Sheep and Goats: Comparative Study
Authors: Galán A. , Martín‐Suárez E. Ma. , Molleda J. Ma.
Published: April 2006

The ocular fundus was examined in 40 goat eyes and 40 sheep eyes by studying ophthalmoscopic characteristics and retinograms. Similarities and differing characteristics were described. In common: tapetal colour; peripheral yellowish area surrounding the Winslow stars; unpigmented areas in the non‐tapetal zone; a great amount of myelin in the optic disc; the Bergmeister's papilla and the holoangiotic retinal vascular pattern. Differences: big size of the Winslow stars in goats; myelinizated fibre over the non‐tapetal zone in sheep; shape, position and myelin distribution of the optic disc; and the presence of a ‘primary artery’ in goats.
Primary Pulmonary Adenocarcinoma Metastatic to the Uvea, Brain and Adrenal Gland in a Dog
Authors: Castellano M. C. , Massone A. R. , Idiart J. R.
Published: April 2006

A 10‐year‐old male Briard dog was presented because of listlessness, abnormal gait, fever, inappetence, and seizures. A non‐pigmented growth was observed in the ventral quadrant of the left iris. Thoracic radiographs revealed multiple pulmonary metastases and the owner opted for killing. On necropsy, lung masses and nodules in left iris, right adrenal medulla, and brain were detected. Histologically the primary tumour was diagnosed as pulmonary adenocarcinoma with predominant solid pattern. Metastases to regional lymph nodes, uvea, adrenal medulla, and brain were recognized. The metastatic behaviour resembled that occurring in humans. To the authors’ knowledge, this is the first report of a pulmonary adenocarcinoma with metastasis to the uvea in a dog.
Primary Haemangiopericytoma in the Pelvic Cavity of a Dog
Authors: Cho H. S. , Park N. Y.
Published: April 2006

A 9‐year‐old female Yorkshire terrier with lameness of the hind leg was examined at the local animal hospital in Gwangju, Republic of Korea on March, 2004. The radiological findings revealed a mass between the urinary bladder and cervix of the uterus. The encapsulated pelvic mass, measuring 4.0 × 3.0 × 2.5 cm was surgically removed. Grossly, the mass was white and firm and microscopically showed a perivascular whorled pattern of spindle cells. By immunohistochemistry, tumour cells tested positive for vimentin and α‐smooth muscle actin, and negative for desmin, S‐100, lysozyme and cytokeratin. The tumour was diagnosed both histologically and immunohistochemically as a haemangiopericytoma. There were no signs of recurrence within 12 months after surgery. This is the first case report of a haemangiopericytoma in the pelvic cavity of a dog.
An exploration of the concept of patient education: Implications for the development of educational programmes for relapsed post‐bone marrow transplantation patients and their families in Korea
Authors: Yoon Soo Jin , Conway Jane , McMillan Margaret
Published: April 2006

Frequently, the nursing care of patients who undergo bone marrow transplantation (BMT) is focused on acute, curative care. However, given that recurrent disease following BMT has a poor prognosis, a focus on acute care alone appears inappropriate for those clients who experience relapse. Care for this group of patients should be more inclusive of principles that underpin palliative care. Patient education is an important element of palliative care. Therefore, patient education based on the principles of palliative care should play a significant part in the nursing care of BMT patients with recurrent disease. This paper proposes a framework for the development of a palliative educational programme for relapsed post‐BMT patients and their families in Korea. The framework was developed through a concept analysis of patient education.
Small cell lung cancer: Treatment review
Authors: COOPER Samantha , SPIRO Stephen G.
Published: April 2006

Abstract:  Lung cancer was relatively uncommon at the turn of the 20th century, and has increased in prevalence at alarming rates, particularly because of the augmented trend in smoking, so that it is now the most common cause of cancer death in the world. As almost a quarter of these cancers are of small cell in origin, it seems only appropriate that small cell lung cancer receives ample attention, rather than seemingly to have been overlooked over the last 10–15 years. Despite its generally late presentation and high risk of dissemination, it is exceptionally sensitive to chemo‐radiotherapy. This review looks at the diverse options of treatment that have been used over the last few years and tries to highlight the best available. As more than 50% of patients diagnosed with lung cancer are over 70 years of age and various studies have shown that older people respond just as well as their younger counterparts, with similar results in response rates, toxicity and outcomes, it is imperative that the older generation are not disregarded in terms of age being a contraindication to therapy.
National survey of spirometer ownership and usage in general practice in Australia
Authors: JOHNS David P. , BURTON Deborah , WALTERS Julia A.E. , WOOD‐BAKER Richard
Published: April 2006

Objectives and background:  Despite the lack of data, it is believed that spirometry is underutilized in general practice. The aim of the present study was to determine the availability of spirometry and the level of spirometry training in general practice throughout Australia and compare with international data.

Methods:  In total, 5976 general practices throughout Australia were sent a questionnaire requesting details of spirometer ownership, usage and the level and source of spirometry training. To exclude response bias, a follow‐up telephone survey was conducted of 160 practices that did not respond to the initial survey.

Results:  Of practices 19.5% (1125) responded to the initial survey with 64.2% (722) of these owning a spirometer and 83.9% in the follow‐up sample. Common reasons for not owning a spirometer were equipment cost (53.3%) and insufficient remuneration (32.8%). Most practices (67.0%) performed one or more tests per week. Practices commonly used spirometry to diagnose (89.5%) and manage (93.9%) asthma, assess breathlessness (83.4%) and to detect and manage other diseases such as COPD (77.7%). Spirometer accuracy was never checked using a syringe 77.8% of practices and 40% did not test a healthy subject as part of their quality assurance programme. Spirometry training was received most commonly through courses run by general practice organizations (38.2%), and the duration of training courses was <2 h in 40% of cases.

Conclusion:  Despite high spirometer ownership in general practice, the frequency of use is low. Low rates of verification of spirometer accuracy and performance suggest the need for reliable, stable spirometers to be available to general practitioners. Regular and more comprehensive training in spirometry is needed.