bluuebunny/crossref_metadata_2025 huggingface dataset:
The high wavenumber instabilities of a Stokes wave
Authors: Hasselmann Dieter E.
Published: April 2006

A stability analysis for high wavenumber perturbations of a Stokes wave of wavenumber k1 and slope ϵ is presented. Except for a correction term the governing equation is shown to be of Hill's type. The analysis predicts instability at wavenumbers k2 = ¼(m + 1)2k1. The two lowest and strongest instabilities are the Benjamin- Feir instability at m = 1, and the quartet resonance at m = 2. Both are incorrectly treated by the present method. For m ≥ 3 the analysis should be asymptotically (ϵ → 0) correct, yielding instability O(ϵm) due to m-fold Bragg-scattering. The non-resonant perturbations behave as predicted by WKBJ theory. The instability is too weak for experimental detection; numerical tests should be possible, but are not available at present.
Turbulent Taylor vortex flow
Authors: Koschmieder E. L.
Published: April 2006

The wavelength of turbulent Taylor vortices at very high Taylor numbers up to 40000Tc, has been measured in long fluid columns with radius ratios η = 0·896 and η = 0·727. Following slow acceleration procedures the wavelength (in units of the gap width) of turbulent axisymmetric vortices was found to be λ = 3·4 ± 0·1 with the small gap and about λ = 2·4 ± 0·1 with the larger gap, and thus in both cases substantially larger than the critical wavelength of laminar Taylor vortices. In the narrow and wide gap the wavelength was, within experimental error, independent of the Taylor number for T > 100Tc. In the experiments with the narrow gap a clear dependence of the value of the wavelength of the turbulent vortices on initial conditions was found. After sudden starts to Taylor numbers > 700Tc the wavelength of steady axisymmetric turbulent vortices was only 2·4 ± 0·05, being then the same as the wavelength of the vortices after sudden starts in the wide gap, and being, within the experimental error, independent of the Taylor number. In the narrow gap all values of the wavelength between λmax = 3·4 and λmin = 2·4 can be realized as steady states through different acceleration procedures. In the wide gap the dependence of the wavelength on initial conditions is just within the then larger experimental uncertainty of the measurements.
A nonlinear unsteady one-dimensional theory for wings in extreme ground effect
Authors: Tuck E. O.
Published: April 2006

Flow induced by a body moving near a plane wall is analysed on the assumption that the normal distance from the wall of every point of the body is small compared to the body length. The flow is irrotational except for the vortex sheet representing the wake. The gap-flow problem in the case of unsteady motion is reduced to a nonlinear first-order ordinary differential equation in the time variable. In the special case of steady flow, some known results are recovered and generalized. As an illustration of the unsteady theory, the problem is solved of a flat plate falling toward the ground under its own weight, while moving forward at uniform speed.
A note on an algebraic instability of inviscid parallel shear flows
Authors: Landahl M. T.
Published: April 2006

It is shown that all parallel inviscid shear flows of constant density are unstable to a wide class of initial infinitesimal three-dimensional disturbances in the sense that, according to linear theory, the kinetic energy of the disturbance will grow at least as fast as linearly in time. This can occur even when the disturbance velocities are bounded, because the streamwise length of the disturbed region grows linearly with time. This finding may have implications for the observed tendency of turbulent shear flows to develop a longitudinal streaky structure.
Oscillatory flow in curved pipes. Part 1. The developing-flow case
Authors: Mullin T. , Greated C. A.
Published: April 2006

The results of an experimental investigation of the entry, into a curved pipe, of the fully developed oscillatory laminar flow in a straight section are presented. Laser anemometry has been used to measure velocity profiles in the plane of the bend at various stations around a 180°-curved section. The flow development is found to depend upon both the frequency parameter of the flow and the amplitude of oscillation.

Results are presented for two values of the frequency parameter α. The first is for small α where the flow can be considered quasi-steady and the flow development is found to proceed as in previous steady-flow studies. The other case, more extensively studied, is where α has a value such that both viscous and inertial effects play important roles in establishing the basic flow at different parts of the pressure cycle. The flow development process around the curve is found to be complicated, but a general trend is found and the results are explained in terms of those already established for steady-flow development in a curved pipe.
On the severe non-symmetric constriction, curving or cornering of channel flows
Authors: Smith F. T. , Duck P. W.
Published: April 2006

Considered below is the plane, high-Reynolds-number (Re), flow of an incompressible fluid through a channel suffering a severe non-symmetric constriction, ‘severe’ meaning ‘of typical dimensions comparable with the channel width a*’. The (mainly inviscid) flow description is governed by free streamline theory, to be consistent with the viscous incompressible separation from the constriction surface and with a relatively slow eddy motion beyond. Separation also occurs far ahead of the constriction, at a distance $O(Re^{\frac{1}{7}} a^{*})$ upstream. Attention is given primarily to the flow features for a particular class of slowly varying severe constrictions, from which however the features for the probably more useful classes of slender (i.e. of large length but O(a*) height) and moderately severe (i.e. of O(a*) length but small height) constriction follow, as do those for curved or cornered channel flows. In all these cases a long-scale flow response is induced upstream and downstream and in many cases remarkably simple universal formulae for the separation and reattachment positions result. The corresponding O(a*) corrections to the upstream separation distance above are also derived.
Double-diffusive instability in an inclined fluid layer Part 2. Stability analysis
Authors: Paliwal R. C. , Chen C. F.
Published: April 2006

Linear stability analysis is applied to the problem of a density-stratified fluid contained in an inclined slot being subjected to a lateral temperature gradient. Stability equations are solved using the Galerkin technique with 12 terms in the truncated expansion series. Within the range of θ considered, |θ| < 75°, critical instability was found to be of the stationary type. Results of critical thermal Rayleigh numbers and wavenumbers at all inclination angles are in good agreement with the experimental results obtained earlier (Paliwal & Chen 1980). Contrary to intuition, these results show that the system is more stable when the lower wall is heated. This is shown to be the result of the increased vertical solute gradient in the steady state prior to the onset of instabilities when the heating is from below.
An analysis of advective diffusion in branching channels
Authors: Hamblin P. F.
Published: April 2006

Solutions to the steady advection–diffusion equation in a branching channel are obtained for both uniform and spatially varying flow fields and for two channel geometries. An interesting feature of the solutions is that anisotropy of the dispersion coefficients in the direction of the streamlines may be accounted for. The analysis reveals that mixing is confined to a distance, b2U/π2KN, downstream of the junction in the advection-dominated case and a distance, KS/U, upstream in the diffusion-dominated situation, KS and KN being the diffusivities along and across the flow respectively, U the characteristic velocity of the flow, and b the breadth of channel downstream of the junction.
On the stability of rotating compressible and inviscid fluids
Authors: Eckhoff Knut S. , Storesletten Leiv
Published: April 2006

Necessary conditions for linear stability of a rotating, compressible and inviscid fluid are found by the generalized progressing wave expansion method. The full three-dimensional problem involving an arbitrarily given rotational symmetric external force field is considered for an arbitrary steady shear flow with vanishing axial velocity. The results obtained are compared with previously known results.
Dispersion effects on thermal convection in porous media
Authors: Kvernvold Oddmund , Tyvand Peder A.
Published: April 2006

The influence of hydrodynamic dispersion on thermal convection in porous media is studied theoretically. The fluid-saturated porous layer is homogeneous, isotropic and bounded by two infinite horizontal planes kept at constant temperatures. The supercritical, steady two-dimensional motion, the heat transport and the stability of the motion are investigated. The dispersion effects depend strongly on the Rayleigh number and on the ratio of grain diameter to layer depth. The present results provide new and closer approximations to experimental data of the heat transport.
Autorotation of an elliptic cylinder about an axis perpendicular to the flow
Authors: Lugt Hans J.
Published: April 2006

Autorotation of an elliptic cylinder about an axis fixed perpendicular to a parallel flow is explained in this paper by means of numerical solutions of the Navier-Stokes equations. Potential-flow theory predicts, for constant angular velocity, half a period in which a torque supports rotation and half a period in which it opposes rotation, with vanishing torque in the average. This balance is disturbed by viscous-flow effects in such a way that, for a given angular velocity, vortex shedding either damps rotation or, under certain conditions, favours rotation. The proper interplay of those conditions, which include synchronization of vortex shedding and rate of rotation, results in auto-rotation. The numerical results forRe[les ] 400 are compared with experimental data forRe= 90000 from the literature. The agreement of the force coefficients and the large-scale flow patterns is surprisingly good.
Flow past a thin, inflated lenticular aerofoil
Authors: Newman B. G. , Tse M.-C.
Published: April 2006

A study has been made of the flow past thin, inflated lenticular aerofoils at zero angle of incidence. The configuration is an idealization of the flow past long low inflated buildings when the effects of the earth's boundary layer are neglected. It is shown theoretically, and confirmed experimentally, that the non-dimensional tension coefficient in the inflated membranes comprising the aerofoil is a unique function of the internal pressure coefficient divided by the square root of the excess-length ratio. This applies for excess length ratios up to at least 0·05 which corresponds to a thickness-to-chord ratio, wind off, of 0·28. The aerofoil is found to become unstable at negative internal pressures corresponding to tension coefficients of approximately 0·4.

The theory has also been used to predict the shape of the aerofoil and the pressure distribution over it. With increasing wind speed at positive internal pressures, the membrane theoretically changes shape from a circular arc to a form involving inflexion points and in all cases the contours are symmetrical about the half-chord point. The non-dimensional membrane slope at the leading and trailing edges agrees fairly well with the experimental values. However, the measured pressure distributions show some fore-and-aft asymmetry and the maximum thickness is slightly downwind of the half-chord point. Nevertheless the comparison between theory and experiment is satisfactory for small values of the excess-length ratio.
Weld-pool sag
Authors: Andrews J. G. , Atthey D. R. , Byatt-Smith J. G.
Published: April 2006

The shape of the liquid/gas interface of a weld pool is determined by the balance of gravitational and surface tension forces. Equilibrium profiles and stability criteria are derived for vertical and horizontal situations.
An experimental study of the surface elevation probability distribution and statistics of wind-generated waves
Authors: Huang Norden E. , Long Steven R.
Published: April 2006

Laboratory experiments were conducted to measure the surface elevation probability density function and associated statistical properties for a wind-generated wave field. The laboratory data together with some limited field data were compared. It is found that the skewness of the surface elevation distribution is proportional to the significant slope of the wave field, §, and all the laboratory and field data are best fitted by
\[
K_3 = 8\pi\S,
\]
with § defined as ($(\overline{\zeta^2})^{\frac{1}{2}}/\lambda_0 $, where ζ is the surface elevation, and λ0 is the wavelength of the energy-containing waves. The value of K3 under strong wind could reach unity. Even under these highly non-Gaussian conditions, the distribution can be approximated by a four-term Gram-Charlier expansion. The approximation does not converge uniformly, however. More terms will make the approximation worse.
Rotating barotropic flow over finite isolated topography
Authors: Bannon Peter R.
Published: April 2006

The flow of a rotating, incompressible fluid over isolated topography whose non-dimensional height (i.e. topographic height divided by the mean fluid depth) is large compared with the Rossby number is studied. Attention is restricted to flow which is sufficiently shallow that the free-surface equations provide an adequate description. The flow is forced laterally by a specified upstream inflow (obtained from solutions of the zonally symmetric model equations) and by a prescribed surface stress. Dissipation is incorporated using a Rayleigh friction acting anti-parallel to the flow.

Steady-state solutions for uniform inflow on an f-plane are found for (a) linear viscous flow, (b) quasi-geostrophic flow with and without friction and (c) inviscid flow with and without a rigid lid. The presence of friction produces an upstream–downstream flow asymmetry over the obstacle and an associated topographic drag while inertial terms produce left-right (relative to an observer looking downstream) asymmetry. The blocking efficiency B (the percentage of the incident mass flux going around the obstacle rather than over it) of a Gaussian obstacle is largest (∼ 100%) for case (a) when viscous effects are small. In contrast quasi-geostrophic theory calculates no flow blocking (B ≡ O). For inviscid inertial theory, B ∼ 10% and is independent of the Rossby number. The presence of a free surface decreases the blocking for small-Rossby-number flow.

Numerical solutions of the appropriate initial, boundary-value problem for the complete model equations confirm these results and extend them to include the effects of (i) horizontal shear in the upstream inflow, (ii) the magnitude and shape of the topography, and (iii) variations in the Coriolis parameter (β-effect).
Shock detachment from cones in a relaxing gas
Authors: Hornung H. G. , Houwing A. F. P.
Published: April 2006

Measurements of the shock stand-off distance on cones of various base diameters in carbon dioxide and nitrogen flows with dissociative relaxation show that the detachment process occurs more gradually with relaxation than in a perfect gas, as the cone semi-angle is increased. This is in agreement with a prediction which is made on the basis of the behaviour of the sonic surface in the flow field. The phenomenon is similar to that observed previously with wedge flow but shows interesting effects peculiar to the cone flow. The cone experiments also eliminate the end effect and permit easy variation of the relaxation rate parameter without changing the gas. Perfect-gas argon experiments provide a convenient check.
Dynamical cascade models for Kolmogorov's inertial flow
Authors: Lee Jon
Published: April 2006

To resolve possible fluctuations about the mean motion of the Desnyansky-Novikov model for Kolmogorov's inertial flow, we have investigated two dynamical systems of the cascade process which are formally derivable from Burgers’ equation. The first cascade model produced no fluctuations, for its trajectory was identical with the Desnyansky–Novikov model's. Disappointingly, the second cascade system, which is similar to the Kerr–Siggia model, has also proved unable to engender fluctuations. This is because the second model when truncated consistently maps an arbitrary initial point into the attainable phase space of the first cascade model. However, when truncated inconsistently the trajectory of second model can exhibit a quite erratic and somewhat sporadic motion, thereby reflecting the apparently random motion of inviscid equilibrium solutions. Therefore, the observation of temporally intermittent fluctuations by a stationary Kerr–Siggia model is due to the inconsistent truncation produced by restricting energy dissipation for all but the upper truncation mode in their model.
Refraction–diffraction model for linear surface water waves
Authors: Lozano Carlos , Liu Philip L.-F.
Published: April 2006

Based on the parabolic approximation, a refraction—diffraction model for linear water waves is developed. With the assumption that the water depth (refraction index) is slowly varying, the model equation describes the forward-scattered wavefield. Two examples are considered in particular: (i) wave diffraction by a long thin barrier on a uniform slope, and (ii) wave convergence over a semicircular step shoal. For the former problem, a similarity solution in terms of Fresnel integrals is obtained for the wavefield in the neighbourhood of the shadow boundary. For the latter problem, the resulting Schrödinger equation is solved numerically. The wavefield near the caustics as well as in the shadow region is obtained and compared with experimental data.
On the skewness of the temperature derivative in turbulent flows
Authors: Sreenivasan K. R. , Tavoularis S.
Published: April 2006

This note provides some explanation of the fact that, contrary to the requirements of local isotropy, the skewness S of the streamwise temperature derivative ∂θ/∂x1 has been observed to be a non-zero constant of magnitude of about unity in high-Reynolds-number and high-Péclet-number turbulent shear flows. Measurements in slightly heated homogeneous shear flows and in unsheared grid turbulence suggest that S is non-zero only when the mean shear dU1/dx2 and the mean temperature gradient dT/dx2 are both non-zero. The sign of S is given by –sgn (dU1/dx2).sgn (dT/dx2). For fixed dU1/dx2, S is of the form tanh (αdT/dx2), α being a constant, while for fixed dT/dx2, it is of the form S/S* = 1 − β1 exp (− β2τ), where S* is a characteristic value of S, β1 and β2 are positive constants, and τ can be interpreted as a ‘total strain’. The derivative skewness data in other (inhomogeneous) shear flows are also compatible with the latter relation. Predictions from a simplified transport equation for $\overline{(\partial\theta/\partial x_1)^3}$, derived in the light of the present experimental observations, are in reasonable agreement with the measured values of S. A possible physical mechanism maintaining S is discussed.
Effects of the motion of dust particles on turbulence transport equations
Authors: Genchev Zh. D. , Karpuzov D. S.
Published: April 2006

A generalized eddy-viscosity function νT, is introduced in order to express the Reynolds stress in an incompressible dusty gas as a linear combination of the Kronecker and rate-of-strain tensors. On the basis of Saffman's dusty-gas model a transport equation for the eddy viscosity is derived from the general turbulence energy equations, thereby introducing two additional functions, the specific turbulence kinetic energy E1, and a scale variable s. In order to determine the three variables modified Prandtl–Wieghardt relation among them is accepted and a transport equation for s is postulated in the same manner as in the clean-gas turbulence transport model (firstly proposed by Harlow & Nakayama 1967) but with the inclusion of an additional term accounting for the dust particles stabilizing action. We are considering values of loading (mass ratio of particles) of order of unity, with particle/gas density ratios of order of 103 and volume concentrations of the order of 10−3, so that particle–particle interactions are neglected. Supposing that the particles nearly follow the gas motion, following well at large scales and poorly at small, an application of the theory to problem of numerical calculations of the dusty-gas parameters such as mean velocity profile of turbulent pipe flow is given.
The nonlinear capillary instability of a liquid jet. Part 2. Experiments on jet behaviour before droplet formation
Authors: Chaudhary K. C. , Maxworthy T.
Published: April 2006

The behaviour of a perturbed capillary jet is experimentally determined by studying the jet from the time it emerges from a small hole to the point at which individual droplets of fluid begin to form. Under any particular set of externally applied experimental parameters, i.e. jet velocity, disturbance wavenumber and amplitude, there is a unique, minimum time to this breakup into drops. This characteristic is needed to relate the magnitude of the input voltage to the modulating device and the output velocity perturbation that it produces. Using this relationship we then compare the experimentally produced profiles of jet shape to corresponding ones calculated by using the theory of Chaudhary & Redekopp (1980). The agreement is satisfactory, especially for small values of input voltage. Then, in the neighbourhood of the cutoff wavenumber, we show that the predicted linear growth of the jet profile is also reproduced in the experimental model.
Crisis at the Theatre Museum
Authors: Herbert Ian
Published: April 2006

As this issue of New Theatre Quarterly was going to press, we learned of a threat to the continued existence of the Theatre Museum in Covent Garden. The following personal response by NTQ Contributing Editor Ian Herbert may well have been overtaken by events by the time this issue is published, but we felt the situation should not go unrecorded or unprotested. Any interested readers who have not yet added their voices in support of the Museum should visit http://theatremuseum.org/news_and_views/phpbb/viewtopic.php?t=3582 where up-to-date news is, at the time of writing, being posted.
Comparison of JNK (c‐Jun N‐terminal kinase)‐like MAPK (mitogen‐activated protein kinase) phosphorylation between immobilized cultures and Couette‐type shear reactor cultures of Taxus cuspidata (Japanese yew) cells
Authors: Cheng Jing‐Sheng , Yuan Ying‐Jin
Published: April 2006

The signal mechanism of Taxus cuspidata (Japanese yew) cells involved in response to shear stress and immobilized matrices was investigated. Western‐blot analysis showed that the immobilized cultures altered the degree of phosphorylation of the JNK (c‐Jun N‐terminal kinase)‐like and a 41 kDa p38‐like MAPKs (mitogen‐activated protein kinases), particularly the 52 and 45 kDa JNK‐like MAPKs. The increased rotation speeds up‐regulated the degree of phosphorylation of 45 and 47 kDa JNK‐like MAPKs, whereas the 41 kDa p38‐like MAPK was not significantly changed. The level of phosphorylation of JNK‐like MAPKs in the outer zone cells of immobilized matrices was the highest among the different zone cells, which was identical with that of T. cuspidata cells exposed to hydrodynamic shear stresses. The highly specific p38‐ or JNK‐MAPK inhibitors strongly reduced respectively the p38‐ or JNK‐like MAPK phosphorylation, which also demonstrated that there were no cross‐reactions between the p38‐like MAPK and JNK‐like MAPK in T. cuspidata cells. By a comparison of the effects of the immobilization and laminar shear stress on the phosphorylation of p38‐ and JNK‐like MAPKs in T. cuspidata cells, these findings suggested that the JNK‐like MAPK signal pathways may be involved in T. cuspidata cell response to the hydrodynamic shear stress, rather than to the p38‐like MAPK.
Continuous hybridoma bioreactor: sensitivity analysis and optimal control
Authors: Lavric Vasile , Ofiţeru Irina Dana , Woinaroschy Alexandru
Published: April 2006

Animal cell culture has already established itself as a mature technology able to make a wide range of valuable products, the actual focus being to find the competitive bioreactor design and operating conditions for increasing production. A complex analysis, implying sensitivity calculus and optimal control computation, is done for a system composed of a continuous perfectly mixed bioreactor, with cell recirculation, a cell separator, a mixer and a purge. The bioreactor's sensitivity to the control parameters is measured by a new concept, entropic density, developed from the notion of Shannon entropy. An optimization procedure based on a genetic‐algorithms approach is applied for the computation of the inlet flow profile in time, which guarantees optimum monoclonal‐antibody production. Our studies, including the present one, proved that the best approach to obtain high production is to use a hybrid operating sequence: fed‐batch mode followed by the continuous mode.
Kinetics of Si incorporation into a Ge matrix for Si1−xGex layers grown by chemical vapor deposition
Authors: Tomasini P. , Bauer M. , Cody N. , Arena C.
Published: April 2006

The growth rate and alloy composition of Si1−xGex layers grown in an industrial chemical vapor deposition (CVD) system have been analyzed as functions of the process parameters at a pressure enabling selective epitaxial growth. We systematically investigate the growth of Si1−xGex with 0.48<x<0.8, using GeH4∕SiCl2H2 partial pressure ratios up to 1.12, where the GeH4 flow was constant and the SiCl2H2 flow was varied. Epitaxial growth temperatures spanned from 350to600°C. The growth rate and alloy composition were limited by the surface reaction step with an activation energy of 1eV∕mol. A significant growth rate reduction is observed when increasing Si content. This feature is consistent with a passivation of the surface Si bonds with H and Cl atoms typical of chemical vapor deposition Si1−xGex layer growth. It is found empirically that x∕(1−x)∝pDCSΔn, Δn=0.32, where x is the Ge mole fraction and pDCS is the SiCl2H2 partial pressure. Then we tentatively develop a model to support the empirical laws found without making any assumption on the mechanism and we extend it to the full compositional range of CVD grown Si–Ge alloys.
Thickness dependences of ferroelectric and dielectric properties in (Bi3.15Nd0.85)Ti3O12 thin films
Authors: Gao X. S. , Wang J.
Published: April 2006

( Bi 3.15 Nd 0.85 ) Ti 3 O 12 (BNdT) thin films deposited by rf sputtering on Pt∕TiO2∕Si substrates demonstrate thickness dependences of electrical properties. The films exhibit well-established ferroelectric hysteresis loops with an almost thickness independent 2Pr of ∼23μC∕cm2 at 500kV∕cm. However, their nonvolatile polarization shows a monotonous decrease with increasing thickness at low operation voltages. Their coercive voltages exhibit an increase with increasing film thickness, which is accounted for by the existence of an interfacial nonferroelectric dead layer. Their dielectric permittivity demonstrates frequency and thickness dependent behavior, supporting the existence of the interfacial dead layer. The film thickness also affects both the reversible and irreversible components in the ac field dependence of relative permittivity.
Direct 120V, 60Hz operation of an organic light emitting device
Authors: Slinker Jason D. , Rivnay Jonathan , DeFranco John A. , Bernards Daniel A. , Gorodetsky Alon A. , Parker Sara T. , Cox Marshall P. , Rohl Richard , Malliaras George G. , Flores-Torres Samuel , Abruña Héctor D.
Published: April 2006

We report on lighting panels based on ruthenium(II) tris-bipyridine complexes that can be sourced directly from a standard US outlet. With the aid of the ionic liquid 1-butyl-3-methylimidazolium, the conductivity of the light emitting layer was enhanced to achieve device operation at a 60Hz frequency. Lighting panels were prepared using a cascaded architecture of several electroluminescent devices. This architecture sustains high input voltages, provides fault tolerance, and facilitates the fabrication of large area solid-state lighting panels. Scalability of the drive voltage, radiant flux, and external quantum efficiency is demonstrated for panels with up to N=36 devices. Direct outlet operation is achieved for panels with N=16, 24, and 36 devices.
Influence of polarization-induced electric field on the wavelength and the absorption coefficient of the intersubband transitions in AlxGa1−xN∕GaN double quantum wells
Authors: Lei S. Y. , Shen B. , Cao L. , Xu F. J. , Yang Z. J. , Xu K. , Zhang G. Y.
Published: April 2006

The influence of the polarization-induced electric field on the wavelength and the absorption coefficient of the intersubband transitions (ISBTs) in AlxGa1−xN∕GaN coupled double quantum wells (DQWs) have been investigated by self-consistent calculation. It is found that the wavelength of the ISBT between the first odd order and the second even order subbands (the 1odd-2even ISBT) can be shortened to 1.3μm owing to the Stark shift induced by the polarization effect. The absorption coefficient of the 1odd-2even ISBT decreases by increasing the polarization field discontinuity. On the other hand, a shorter wavelength and a larger absorption coefficient of the ISBTs are obtained by decreasing the width of the central barrier of AlxGa1−xN∕GaN DQWs. The results are beneficial to achieving devices operation within the optical communication wavelength range.
The 1.23 and 1.47μm emissions from Tm3+ in chalcogenide glasses
Authors: Yang Zhiyong , Luo Lan , Chen Wei
Published: April 2006

The 1.23 and 1.47μm emission properties of Tm3+ in the low-phonon-energy Ge–Ga–Sb–S chalcogenide glasses were reported. Radiative parameters were calculated based on a Judd-Ofelt analysis and the laser actions of the transitions were analyzed. The 1.23μm transition has a branching ratio of 98.9%, a fluorescence lifetime of 1535μs, a quantum efficiency of 95.5%, and a stimulated emission cross section of 6.03×10−21cm2 in 0.1mol% Tm3+-doped Ge25Ga5Sb5S65 glass, which makes the Tm3+-doped glasses attractive for fiber optical amplifiers working at 1.21–1.27μm. The 1.47μm emission may also have potential applications in fiber optical amplifiers operating at 1.42–1.50μm.
Effect of internal bias field on domain switching in (CH3NH3)5Bi2Br11 crystal
Authors: Matyjasek K. , Rogowski R. Z.
Published: April 2006

In this report we investigate the microscopic features of 180° domain wall dynamics and relate its dynamics to the defect structure in unipolar methylammonium bromobismuthate, (CH3NH3)5Bi2Br11, single crystal. The switching and spontaneous backswitching processes have been studied by observation of domain structure by using nematic liquid crystal method and by switching current registration. We found a two-step relaxation decay of polarization induced by Eb; the fast one decays on the time scale of milliseconds, while the slow one lasts over seconds. In the late-time regime, the stretched-exponential function was used as an empirical fit of relaxation data.
MgO(100) template layer for CdO thin film growth: Strategies to enhance microstructural crystallinity and charge carrier mobility
Authors: Wang Lian , Yang Yu , Jin Shu , Marks Tobin J.
Published: April 2006

A simple strategy of using thin, highly (100)-oriented MgO films as template layers for CdO thin film growth by metal-organic chemical vapor deposition on amorphous glass substrates is presented. For comparison, CdO films are grown simultaneously on clean glass, on a 50nm MgO(100) template layer on glass, and on single-crystal MgO(100). X-ray diffraction as well as four-probe conductivity and Hall-effect measurements reveal that the 50nm MgO(100) template layer significantly improves the microstructural texture and charge carrier mobility of the overlying CdO thin films. Thus, highly textured CdO thin films with an x-ray diffraction rocking curve full width at half maximum of 2.1° and large carrier mobilities of 160cm2∕Vs can be achieved on amorphous glass. Substrate effects, film microstructures, optical properties, and surface morphologies of the CdO films on the different substrates are discussed.
Smoothening mechanism for GaAs(100) surfaces during ion-enhanced plasma etching
Authors: Lee S. H. , Gillis H. P. , Ratsch C.
Published: April 2006

We present experimental data showing the development of smooth surfaces on GaAs(100) exposed simultaneously to ion bombardment and reactive species in chlorine plasma. With negligible ion bombardment, the surface develops ⟨110⟩ ridges and {111} facets, as in purely chemical etching. With ion bombardment at energy 27eV, formation of ridges and facets is reduced, and at 110eV the etched (100) surface has a root-mean-square roughness of 0.5nm. Kinetic Monte Carlo simulations suggest that low energy ion bombardment modifies the relative ratios of reaction rates at specific sites from their purely chemical values to give the smooth surface.
A Novel DNA Sequence Variation in the First Genetically Confirmed Allgrove Syndrome in Iran
Authors: Haghighi Afshin Borhani , Houlden Henry , Lankarani Kamran Bagheri , Taghavi Alireza , Masnadi Kurosh , Ashraf Ali Reza , Safari Anahid
Published: April 2006

Allgrove syndrome or triple-A syndrome is an autosomal recessive disorder characterized by adrenal insufficiency, achalasia and alacrima. Affected patients may also present with a constellation of central and peripheral nervous system manifestations. The gene for Allgrove syndrome (ALADIN) is located on chromosome 12q13. Here we report a 23-year-old man with alacrimia, achalasia, optic atrophy and progressive amyotrophic lateral sclerosis-like presentations. Sequencing of ALADIN gene showed a novel 6-bp sequence variant that the patient was homozygous and his father was heterozygous for the defect. A probable mechanism of action of this newly diagnosed missense mutation would be to cause abnormal splicing of the ALADIN gene.
Detection of Bovine Torovirus in Neonatal Calf Diarrhoea in Lower Austria and Styria (Austria)
Authors: Haschek B. , Klein D. , Benetka V. , Herrera C. , Sommerfeld‐Stur I. , Vilcek Š. , Moestl K. , Baumgartner W.
Published: April 2006

Faeces of 230 calves with and without diarrhoea collected during the winter period 2004/2005 in 100 Austrian farms (Styria and Lower Austria) were examined for viral, bacterial and parasitic enteropathogens. Torovirus‐specific nucleic acid confirmed by reverse transcriptase‐polymerase chain reaction was found in 12 of 230 calves (5.2%). Ten of these calves were clinically ill, several of them showing signs of dehydration and abnormal faecal consistency at the time of sampling. Computer assisted analysis of two nucleotide sequences obtained from Austrian bovine samples revealed 93% similarity to Breda strain, but only 71% or 52% similarity to Equine Berne or Porcine Markelo torovirus strains respectively. Phylogenetic analysis grouped Austrian torovirus samples into the Bovine torovirus cluster indicating the first detection of Bovine torovirus in Austria. In addition, the following agents were detected in bovine faecal samples: Bovine coronavirus, 25.7%;Escherichia coli, 17%;Cryptosporidiumspp., 11.7%;Eimeriaspp., 10.4%; Rotavirus, 9.1%;Clostridium perfringens, 9.1% andGiardiaspp., 6.1%.Salmonellaspp. was not detected.
Genetic Characterization of Anaplasma (Ehrlichia) platys in Dogs in Spain
Authors: Aguirre E. , Tesouro M. A. , Ruiz L. , Amusategui I. , Sainz A.
Published: April 2006

This paper reports the first genetic characterization of Anaplasma (Ehrlichia) platys in Spain from a naturally infected dog. The dog presented clinical signs compatible with canine ehrlichiosis. After DNA extraction and PCR amplification, 16S rRNA gene and citrate synthase gene ( gltA) of this agent were amplified. The GenBank accession number for the nucleotide sequence of the 16S rRNA gene of this strain is AY530806. The A. platys strains registered in France and Japan showed the highest similarity to the 16S rRNA gene sequence obtained from the Spanish strain. In the amplification of the gltA gene, a 1443 bp fragment was obtained, and three nucleotide differences were detected in comparison with other strains sequences. These data confirm the presence of A. platys in a dog showing clinical signs compatible with ehrlichiosis in Spain.
Self‐reported subjective sleep quality and fatigue in patients with peritoneal dialysis treatment at home
Authors: Yngman‐Uhlin Pia , Edéll‐Gustafsson Ulla
Published: April 2006

The aim of this study was to describe habitual sleep, daytime symptoms, sleep‐disturbing factors, current sleep during 1 week and fatigue in patients with peritoneal dialysis treatment at home and also discover predictions for sleep quality outcome. The knowledge should increase possibilities for supportive nursing health care. Fifty‐five patients answered two mailed questionnaires and filled in a sleep diary. Of these, 60% had moderate, persistent sleep problems combined with daytime symptoms. Nocturnal awakenings with difficulties falling asleep again and a sleep duration predicted as 57% of sleep quality. Nocturnal pruritus and ‘difficulties finding a comfortable sleeping position’ were significant sleep‐disturbing factors. Sleep quality predictors means progress in knowledge about the complexity of the situation for peritoneal dialysis patients. Poor sleep, daytime symptoms, sleep‐disturbing factors and chronic fatigue need to be enlightened, especially for the nephrology nurses who are in a unique position to give supportive nursing health care.
Epidermal growth factor receptor targeted therapy with gefitinib in locally advanced and metastatic primary lung adenocarcinoma
Authors: LIAM Chong‐Kin , PANG Yong‐Kek , LEOW Chai‐Hooi
Published: April 2006

Objective:  To describe the efficacy of monotherapy with the epidermal growth factor receptor‐tyrosine kinase inhibitor, gefitinib in patients with locally advanced and metastatic primary lung adenocarcinoma.

Methods:  A retrospective analysis was undertaken of patients who had locally advanced or metastatic lung adenocarcinoma treated with gefitinib 250 mg orally once daily until disease progression. All patients had either been previously treated with systemic cytotoxic chemotherapy and/or radiotherapy or had declined chemotherapy or were medically not fit for cytotoxic chemotherapy.

Results:  A total of 23 patients (13 men) (15 never smokers) with a median age of 51 years (range 35–79 years) received gefitinib monotherapy. Disease control occurred in 14 patients (61%); there was a reduction in the size of the primary and/or metastatic tumours (partial response (PR)) in 11 patients (48%), and 3 patients (13%) had stable disease. The response rate was significantly higher in those who had never smoked (10 of 15 (67%)) compared with that of smokers (1 of 8 (13%)) (odds ratio (95% confidence interval), 14.0 (1.33–147.43) P = 0.027). In total, 11 of 18 patients (61%) with a WHO performance status 1 or 2 showed a PR, whereas none with a performance status 3 or 4 responded (P = 0.037). Response was not affected by the patient's age, gender, disease stage, prior chemotherapy treatment, interval between diagnosis and commencement of gefitinib or the development of skin toxicity. The median time to symptom improvement was 1.5 (range 0.5–6) weeks. The median progression‐free survival time was: 60 (range 15–138) weeks in patients with PR and 34 (range 7–38) weeks in patients with stable disease (P = 0.368).

Conclusion:  When given alone, gefitinib showed significant antitumour activity in patients with locally advanced and metastatic primary lung adenocarcinoma. An objective response was observed more frequently in never smokers and exclusively in patients with good performance status.
Fans, Football and Federal Elections: A Real‐World Example of Statistics
Authors: Cramer Kenneth M. , Jackson Dennis L.
Published: April 2006

This article evaluates and explores the correlation (+0.892) between the United States federal election winner and the most recent Washington Redskin home‐game winner, a relation perfectly linked for 17 of 18 elections since franchise inception in 1936.
A generic method of pesticide dose expression: Application to broadcast spraying of apple trees
Authors: WALKLATE P J , CROSS J V , RICHARDSON G M , BAKER D E , MURRAY R A
Published: April 2006

The recommended dose for many pesticides is expressed as a constant mass or volume per unit ground area covered by the crop. This method of dose expression is well suited to boom spraying where a reasonably uniform horizontal distribution of deposit can be achieved with a well‐adjusted sprayer. However, in many practical situations (e.g. broadcast spraying of apple trees or other row structures where the spray application is made from within the canopy) the horizontal deposit distribution is strongly influenced by the crop area density and other crop structural parameters. This paper describes a generic method of pesticide dose expression to investigate these effects. The method incorporates a model of the spray volume deposition process. The model assumes that the pesticide deposit is proportional to the tank‐mix concentration of pesticide. The model also assumes that spray volume deposit is proportional to the applied spray volume per unit row length and is inversely proportional to a crop length scaling function L (i.e. a parameter with the units of length that is expressed as a generic function of different crop parameters). The useful working range of this model is bounded by the condition for high spray volume where target losses become significant due to saturation and the condition for very low volume where evaporative transport losses become significant. Within this framework, four different models are formulated using first‐order approximations for the length‐scale as functions of the following crop parameters: tree row spacing, tree row height, tree area density and tree row volume to ground area ratio. Published measurements of crop structure and spray volume deposit on apple trees are compared with the output from these models. Light detection and range (LIDAR) measurements of apple orchards are presented and used in conjunction with the different models to predict pesticide use associated with different methods of dose expression. The results demonstrate the relative potential for varying the pesticide application rate according to the different crop parameters. The results enable the identification of reference orchards that could be used to establish worst‐case pesticide application rates for registration purposes. The results also enable the identification of other orchards and growth stages where pesticide application rate might be reduced by up to a factor of five and give the same pesticide deposit as the reference structure.
MULTIPLIER IDEAL SHEAVES ON FIBRED PRODUCTS OF CERTAIN SINGULAR VARIETIES
Authors: WESSLER MARKUS
Published: April 2006

In [3], we discussed the compatibility of multiplier ideal sheaves with fibred products. Multiplier ideal sheaves on singular varieties generalize in a natural way the ℚ-divisors on nonsingular varieties. However, there was one central result in [3] which we proved only for nonsingular varieties. In this paper we extend this to a certain class of singular varieties.
Continuous testosterone administration prevents skeletal muscle atrophy and enhances resistance to fatigue in orchidectomized male mice
Authors: Axell Anna-Maree , MacLean Helen E. , Plant David R. , Harcourt Leah J. , Davis Jennifer A. , Jimenez Mark , Handelsman David J. , Lynch Gordon S. , Zajac Jeffrey D.
Published: April 2006

Androgens promote anabolism in skeletal muscle; however, effects on subsequent muscle function are less well defined because of a lack of reliable experimental models. We established a rigorous model of androgen withdrawal and administration in male mice and assessed androgen regulation of muscle mass, structure, and function. Adult C57Bl/6J male mice were orchidectomized (Orx) or sham-operated (Sham) and received 10 wk of continuous testosterone (T) or control treatment (C) via intraperitoneal implants. Mass, fiber cross-sectional area (CSA), and in vitro contractile function were assessed for fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscles. After 10 wk, Orx+C mice had reduced body weight gain ( P < 0.05), seminal vesicle mass ( P < 0.01), and levator ani muscle mass ( P < 0.001) compared with Sham+C mice, and these effects were prevented with testosterone treatment. Orx+T mice had greater EDL ( P < 0.01) and SOL ( P < 0.01) muscle mass compared with Orx+C mice; however, median fiber CSA was not significantly altered in these muscles. EDL and SOL muscle force was greater in Sham+T compared with Orx+C mice ( P < 0.05) in proportion to muscle mass. Unexpectedly, Orx+T mice had increased fatigue resistance of SOL muscle compared with Orx+C mice ( P < 0.001). We used a rigorous model of androgen withdrawal and administration in male mice to demonstrate an essential role of androgens in the maintenance of muscle mass and force. In addition, we showed that testosterone treatment increases resistance to fatigue of slow- but not fast-twitch muscle.
Upregulation of Id-1 via BMP-2 receptors induces reactive oxygen species in podocytes
Authors: Pache Gregor , Schäfer Christina , Wiesemann Sebastian , Springer Erik , Liebau Max , Reinhardt Hans Christian , August Christian , Pavenstädt Hermann , Bek Martin Johannes
Published: April 2006

Bone morphogenetic proteins (BMPs) are secreted signaling molecules, which play a major role in kidney development and disease. Here, we show the existence of mRNA for BMP-2 and for the BMP receptors BMPR1A, BMPR1B, BMPRII, ACVR1A, ACVR2, and ACVR2B in differentiated mouse podocytes and the protein expression of BMPR1A in human glomerular podocytes. BMP-2 dose dependently increases the free cytosolic Ca2+concentration in podocytes proving the existence of a functional receptor in these cells. Recent data indicate that in a myoblastic cell line and in a breast cancer cell line, BMP-2 increases the expression of Id-1, a negative regulator of basic helix-loop-helix transcription factors, but the role of BMP-2 stimulated Id-1 expression in the kidney has not been further characterized. Here, we show that BMP-2 increases the expression of Id-1 in differentiated podocytes. To investigate a role of Id-1 for podocyte function, overexpression of Id-1 was induced in differentiated mouse podocytes. Id-1-overexpressing podocytes show an increased NADPH-dependent production of reactive oxygen species (ROS). This effect can be evoked by BMP-2 and can be antagonized by anti-Id-1 antisense oligonucleotides. The data indicate that BMP-2 may, via an increased expression of Id-1 and an increased generation of ROS, contribute to important cellular functions in podocytes. ROS supposedly play a major role in cell adhesion, cell injury, ion transport, fibrogenesis, angiogenesis and are involved in the pathogenesis of membranous nephropathy.