bluuebunny/crossref_metadata_2025 huggingface dataset:
EXPERIMENTAL STUDY OF STATIONARY TURING PATTERNS AND THEIR INTERACTION WITH TRAVELING WAVES IN A CHEMICAL SYSTEM
Authors: KEPPER P. DE , PERRAUD J.-J. , RUDOVICS B. , DULOS E.
Published: November 2004

We give a brief review of recent observations of Turing patterns in an isothermal single-phase chemical system. The basic principles of open spatial reactors used in the experiments are described. Different types of one-, two- and three-dimensional symmetry breaking reaction-diffusion patterns are discussed in relation with the geometric dimensions of the reactors and with the localization of the patterned regions in the concentration ramps. We also present a set of new spatiotemporal structures resulting from the interaction of the Turing (spatial) and Hopf (temporal) instabilities. Among other things, these interactions lead to antisymmetric wave sources in quasi-one-dimensional systems and to spatiotemporal intermittency in quasi-two-dimensional systems. We also report on a “cell splitting” growth mechanism of stationary patterns after a supercritical change in parameter value beyond the onset of the Turing instability.
OBSERVATION OF CHEMICAL TURBULENCE IN THE BELOUSOV-ZHABOTINSKY REACTION
Authors: MARKUS MARIO , STAVRIDIS KOSTA
Published: November 2004

Spatio-temporal aperiodicities (turbulence) are experimentally observed in the light sensitive Belousov-Zhabotinsky reaction catalyzed by the ruthenium bipyridyl complex [ Ru(bpy) 3]2+. Turbulence is obtained by a periodically modulated light spot, as well as at constant and uniform illumination. In the latter case, wave front instabilities cause “ripple”-like deformations (at relatively low light intensities) or wave front disruptions (at higher light intensities). Ripples at low illumination are quasiperiodic, while ripples at stronger illumination and disrupted waves have features of chaos, indicating a Ruelle-Takens scenario. Wave front destabilization is related to a change of slope of the experimentally determined eikonal relationship (dependence of the normal velocity of the wave front on its curvature). Wave disruptions lead to aperiodic sequences of spiral formation and destruction, labyrinth-like aperiodic structures, or to a turbulent “gas” of wave pieces.
ADAPTIVE RECOGNITION OF CHAOS
Authors: ARECCHI F.T. , BASTI G. , BOCCALETTI S. , PERRONE A.L.
Published: November 2004

We exploit the information provided by the local variation rates of a chaotic dynamical system, to introduce a stroboscopic observation at adjustable times at which the system displays a regular geometry. The sequence of strobing intervals yields suitable indicators which discriminate deterministic from stochastic signals. The evaluation of these indicators requires a computational effort much smaller than statistical methods.
DYNAMICS OF REACTION-DIFFUSION INTERFACES UNDER STOCHASTIC CONVECTION: PRELIMINARY RESULTS
Authors: CARETA A. , SAGUÉS F. , SANCHO J.M.
Published: November 2004

Some preliminary results to illustrate the effect of turbulent convection on the dynamics of physicochemical systems incorporating reaction, diffusion and convection of chemical species are given. The whole approach rests on the use of stochastic differential equations with spatiotemporal correlated noise. In particular, it is shown how the propagation velocity of a chemically reacting front can be enhanced due to the fluid motion.
FRONT STRUCTURES IN A REAL GINZBURG-LANDAU EQUATION COUPLED TO A MEAN FIELD
Authors: HERRERO HENAR , RIECKE HERMANN
Published: November 2004

Localized travelling wave trains or pulses have been observed in various experiments in binary mixture convection. For strongly negative separation ratio, these pulse structures can be described as two interacting fronts of opposite orientation. An analytical study of the front solutions in a real Ginzburg-Landau equation coupled to a mean field is presented here as a first approach to the pulse solution. The additional mean field becomes important when the mass diffusion in the mixture is small as is the case in liquids.
AMPLITUDE EQUATION IN POLYMERIC FLUID CONVECTION
Authors: MARTÍNEZ-MARDONES J. , TIEMANN R. , ZELLER W. , PÉREZ-GARCÍA C.
Published: November 2004

The convective instabilities in viscoelastic polymeric Oldroyd-B models are studied. First, the nonlinear analysis of the stationary and oscillatory convection is carried out. Then, in the scope of weak nonlinear analysis, the coefficients of the amplitude equations are evaluated, in order to be in condition to estimate the possible behavior of stationary patterns and also travelling and standing waves. The values of these coefficients are determined by means of analytical and numerical techniques for convection in polymeric fluids.
WEAK TURBULENCE IN A HIGH FRESNEL NUMBER DYE LASER
Authors: PÉREZ-GARCÍA VÍCTOR M. , GUERRA J.M.
Published: November 2004

Local spatiotemporal chaos found in a dye laser has been experimentally studied and characterized as a weak turbulent system. Furthermore, a new model based on a discrete version of the Maxwell-Bloch equations seems to agree with the experimental results. The dynamical system’s nonstandard behavior in the form of a new type of frequency locking and the analysis of the decay of the energy fluctuations are herein described from both the theoretical and experimental points of view.
ENCODING OF TRAVELLING WAVES IN A COUPLED MAP LATTICE
Authors: WILLEBOORDSE FREDERICK H.
Published: November 2004

A scheme to encode standing and travelling waves in the diffusively coupled logistic lattice is proposed. A generator for all the possible basic waveforms of the pattern selection regime is derived and applied to accurately predict the ratio of travelling waves in two examples.
ON SYSTEM DECOMPOSITION FOR SYNCHRONIZING CHAOS
Authors: TESI ALBERTO , ANGELI ANDREA DE , GENESIO ROBERTO
Published: November 2004

The problem of the existence of equivalent self-synchronizing systems for a given chaotic system containing a unique stationary and memoryless nonlinear element is addressed. By employing classical frequency domain stability results, one-parameter families of equivalent self-synchronizing systems are given in an explicit way. This degree of freedom may be useful for choosing optimal solutions in practical applications where suitable performance measures are specified.
EXPERIMENTAL VERIFICATION OF PYRAGAS’S CHAOS CONTROL METHOD APPLIED TO CHUA’S CIRCUIT
Authors: CELKA P.
Published: November 2004

We have built an experimental setup to apply Pyragas’s [1992, 1993] control method in order to stabilize unstable periodic orbits (UPO) in Chua’s circuit. We have been able to control low period UPO embedded in the double scroll attractor. However, experimental results show that the control method is useful under some restrictions we will discuss.
RECONSTRUCTING PHYSICAL VARIABLES AND PARAMETERS FROM DYNAMICAL SYSTEMS
Authors: PARLITZ U. , ZÖLLER R. , HOLZFUSS J. , LAUTERBORN W.
Published: November 2004

Variables and parameters of a dynamical system are recovered from a previously generated data base using the time delay reconstruction of states from a single observable. This method may be used for efficiently monitoring variables or parameters of technical systems that are difficult to access. Its application to an electronic oscillator is demonstrated experimentally.
SELF Ck-MOVE, QUASI SELF Ck-MOVE AND THE CONWAY POTENTIAL FUNCTION FOR LINKS
Authors: SHIBUYA TETSUO , YASUHARA AKIRA
Published: November 2004

Nakanishi and Shibuya gave a relation between link homotopy and quasi self delta-equivalence. And they also gave a necessary condition for two links to be self delta-equivalent by using the multivariable Alexander polynomial. Link homotopy and quasi self delta-equivalence are also called self C1-equivalence and quasi self C2-equivalence respectively. In this paper, we generalize their results. In Sec. 1, we give a relation between self Ck-equivalence and quasi self Ck+1-equivalence. In Secs. 2 and 3, we give necessary conditions for two links to be self Ck-equivalent by using the multivariable Conway potential function and the Conway polynomial respectively.
ALGORITHMIC CONSTRUCTION OF KIRBY DIAGRAMS FOR BRANCHED COVERS
Authors: SWENTON FRANK J.
Published: November 2004

We present an algorithm that converts any description of a 3-manifold as a finite-sheeted cover of the 3-sphere, branched over some knot or knotted graph, into a Kirby diagram for that manifold, thus resolving the problem posed in [4].
A SHORT PROOF THAT COMPOSITE TWISTED UNKNOTS ARE SINGLY TWISTED UNKNOTS
Authors: KENT RICHARD P.
Published: November 2004

We present a short proof of a theorem of Hayashi and Motegi and (independently) Goodman-Strauss that only singly twisted unknots are composite.
A COMPARISON OF THE CONVENTIONAL, THE MINIMUM VARIANCE, AND THE MULTIPLE CONSTRAINT MATCHED FIELD PROCESSORS
Authors: LIVINGSTON ELLEN S. , SCHMIDT HENRIK
Published: November 2004

The multiple constraint processor (MCM) is known to be tolerant of water column mismatch while retaining sidelobe control. In this paper, the simulated test cases from the Spring 1993 MFP workshop, which additionally incorporate sediment parameter and bottom depth mismatch, are used to compare the conventional (Bartlett), the minimum variance (MV), and the MCM processors. Peak levels, range and depth estimates, and peak-to-high-sidelobe results are presented. The MCM is shown to maintain sidelobe suppression and correct source localization in all cases at 40 and 10 dB SNR, even when the other two fail. At −5 dB SNR, the MCM is still able to provide good localization in some cases when the Bartlett and the MV cannot.
GLOBAL INVERSION BY GENETIC ALGORITHMS FOR BOTH SOURCE POSITION AND ENVIRONMENTAL PARAMETERS
Authors: GERSTOFT PETER
Published: November 2004

The data set from the Workshop on Acoustic Models in Signal Processing (May 1993) is inverted in order to find both the environmental parameters and the source position, Genetic algorithms are used for the optimization. When using genetic algorithms the responses from many environmental parameter sets are computed in order to estimate the solution. All these samples of the parameter space are used to estimate the a posteriori probabilities of the model parameters. Thus the uniqueness and uncertainty of the model parameters are assessed.
MODEL-BASED SIGNAL ENHANCEMENT FOR THE HUDSON CANYON EXPERIMENT
Authors: CANDY J. V. , SULLIVAN E. J.
Published: November 2004

Model-based signal processing is a well-defined methodology enabling the inclusion of environmental (propagation) models, measurement (sensor arrays) models, and noise (shipping, measurement) models into a sophisticated processing algorithm. Here we investigate the design of a space-varying, nonstationary, model-based processor (MBP) for the Hudson Canyon experiment. In this shallow water application, a state space representation of the normal mode propagation model is used. The processor is designed such that it allows in situ recursive estimation of the both the pressure field and modal functions. It is shown that the MBP can be effectively utilized to "validate" the performance of the model on noisy ocean acoustic data. In fact, a set of processors is designed, one for each source range, and the results are reasonable, implying that the propagation model with measured parameters adequately represents the data.
FORMATION OF $\sqrt {21} \times \sqrt {21} $ STRUCTURE BY GOLD DEPOSITION ON ${\rm{Si}}\left( {111} \right)\sqrt 3 \times \sqrt 3\mbox{-}{\rm{Ag}}$ SURFACE AND THE WAVERING BEHAVIOR
Authors: ICHIMIYA A. , NOMURA H. , HORIO Y. , SATO T. , SUEYOSHI T. , IWATSUKI M.
Published: November 2004

Initial stage of gold deposition on a [Formula: see text] surface at room temperature is observed by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). At gold coverage of 0.14 monolayer (ML) (here 1 ML=7.8×1014 atoms/cm2) a [Formula: see text] structure is formed on the surface. A model of the superstructure is proposed in terms of an embedded arrangement of three gold atoms in the unit cell. Wavering behavior of [Formula: see text] islands formed on the [Formula: see text] structure is found during STM observations.
ANOTHER UNUSUAL ADSORPTION SITE FOR ALKALI ADSORPTION ON A METAL, FOUND BY AUTOMATED TENSOR LEED ON A NOTEBOOK COMPUTER: ${\rm{Rh}}\left( {111} \right) - \left( {\sqrt 3 \times \sqrt 3 } \right)R30^ \circ -{\rm{Na}}$
Authors: VAN HOVE M.A.
Published: November 2004

The surface structure of [Formula: see text] has been analyzed with dynamical low-energy electron diffraction (LEED) at 30 K: a simple Na overlayer is found adsorbed in the unusual hcp-hollow site. LEED theory and computer power have progressed to the point where such a detailed surface structure determination, which includes fitting many structural parameters, is routinely possible even with a portable computer, in this instance a 486/25 MHz notebook computer, using automated tensor LEED.
EFFECTS OF IRRADIATION BY ELECTRON BEAM OF 200 keV ON MELT-TEXTURED GROWTH YBCO AND BSCCO SUPERCONDUCTING FILMS OF 80 nm THICKNESS
Authors: FUNG P.C.W. , CHOW J.C.L.
Published: November 2004

Using our transmission electron microscope (TEM) with operation energy of 200 kV, we have analyzed our melt texture growth (MTG) YBCO and BSCCO specimens by in situ electron beam irradiation. Taking TEM micrographs continuously with regular time intervals, we observed two interesting phenomena: annihilation of twin domains in the MTG YBCO film specimen and elimination of extinction contours of our MTG BSCCO specimen. A simple theory is presented here to calculate the minimum energy needed for twin domains to complete the annihilation process in the MTG YBCO specimen. On the other hand, we have estimated the force needed to change the buckled layer into a flat film under simple assumptions in the MTG BSCCO specimen. Such effect will contribute to the related industry in making better thin film device.
THEORETICAL EVIDENCE FOR UNUSUAL BONDING GEOMETRY AND PHASE TRANSITIONS OF Na ON Al(001)
Authors: STAMPFL C. , NEUGEBAUER J. , SCHEFFLER M.
Published: November 2004

We performed density-functional theory calculations for Na on Al(001) for various coverages from a very low concentration up to a monolayer. From the results we predict that for low coverages the Na atoms occupy on-surface hollow sites which is the stable geometry, but for higher coverages this is only metastable; the stable geometry is reached through a phase transition to a condensed c(2×2) structure where the Na atoms are in surface substitutional sites (contrary to previously suggested models). The mechanism which actuates the island formation with a substitutional geometry is described and the differences to the substitutional adsorption of alkali metals on Al(111) are discussed.
NONEMPIRICAL CLUSTER STUDY OF THE Au ADSORPTION ON THE Si(111) SURFACE
Authors: DOBRODEY N.V. , ZIEGELMAN L.I. , ZAVODINSKY V.G. , KUYANOV I.A.
Published: November 2004

The nonempirical discrete-variational method of local density approximation was used to study the electronic structure and the most stable position of a single Au atom for the Si(111)–Au chemisorption system. Only the symmetric adsorption sites (H3, T4, "on-top") were considered. The three fold hollow site has been found to be energetically the most favorable position with the vertical distance between adsorbed Au atom and the topmost silicon atom plane of 1.59 Å, binding energy of 4.76 eV and vertical vibrational mode of 87 cm –1. The photoemission spectra were calculated and compared with the experimental spectra. Although the calculations suggest that Au atom can not penetrate under the silicon surface, the possibility has been shown for Au atom to replace the surface silicon atom upon the adsorption. The results of the calculations are discussed in connection with the existing models for initial stages of the Au growth on the Si(111) surface.
A NEW DIRECT SURFACE STRUCTURAL PROBE: INVERSION OF MEASURED KIKUCHI ELECTRON PATTERNS
Authors: WEI C.M. , HONG I.H. , CHOU Y.C.
Published: November 2004

The technique of electron-emission holography (EEH) is reviewed with respect to its potential as a direct local structural probe. Direct inversion of the measured Kikuchi electron patterns is emphasized. The description of how the multiple scattering effects are eliminated by the integral-energy phase-summing method is presented. High-fidelity, artifact-free three-dimensional atomic images obtained by inverting simulated diffuse LEED and photoelectron diffraction patterns are shown. Direct inversion of the measured Kikuchi patterns shows clear images of the neighboring atoms within the range of the electron mean free path, thus yielding structural information with high resolution (~1 Å) in all directions. Special attention is paid to the correct role of background subtraction in removing artifacts, and to the selection of minimal experimental data in the practical application of EEH. Moreover, direct inversion of diffraction patterns from many different local emitters is found to yield a three-dimensional Patterson function of the near-surface structure. This leads to direct surface structural determination by inverting Kikuchi electron patterns. Finally, the future of this direct method based upon inverting Kikuchi electron patterns, including the comparison with diffuse LEED and photoelectron holography, is discussed.
FERMI LEVEL PINNING AT A SCHOTTKY BARRIER: Na ON GaAs(110) FROM THE LOW TO THE HIGH COVERAGE REGIME
Authors: HEINEMANN MARTINA
Published: November 2004

The large group of rectifying metal-semiconductor interfaces is better known under the name Schottky barriers or contacts. Their rectifying behavior has been reported for the first time by Braun in 1874 but the understanding of the actual physics at such interfaces is still not complete. This paper summarizes the development of models and shows how modern calculational methods can contribute to a better understanding of Schottky barriers.
NONLINEAR EFFECTS IN ADSORPTION AND REACTION DYNAMICS AT SURFACES: KINETIC OSCILLATIONS UNDER SCRUTINY
Authors: KING DAVID A.
Published: November 2004

A number of catalytic reactions exhibit complex dynamical behavior, including kinetic oscillations with both temporal and spatial characteristics. Attention has been focused on the CO+ NO and CO+O2 reactions on Pt{100}. Recent molecular beam studies conducted at Cambridge on the interaction of CO with Pt{100} have provided the basis for a new mechanism for oscillatory behavior. The rate of growth of (1×1) islands on the quasihexagonal reconstructed phase of Pt{100} is strongly nonlinear with respect to the local CO coverage on the hex-R phase at temperatures between 380 and 410 K, with a reaction order of 4. This strong nonlinearity results in a flux-dependent sticking probability for CO at this temperature, and detailed modeling also reproduces the major features in the oscillatory behavior observed for the CO+NO reaction. An important effect of the nonlinearity in both the CO+NO and CO+O2 oscillatory behavior at high temperatures is the maintenance of in-phase behavior across the surface during oscillations.
DENSITY FUNCTIONAL AND QUASIPARTICLE CALCULATIONS ON THE GaAs(110) SURFACE
Authors: JENKINS S.J. , SRIVASTAVA G.P. , INKSON J.C.
Published: November 2004

We present calculations of quasiparticle band structures for the GaAs(110) surface, performed within a particularly simple tight-binding model for the self energy. Despite its simplicity the model includes contributions from electronic interaction with surface plasmons in addition to both local field and dynamic effects. The resulting quasiparticle band structure is in excellent agreement with recent theoretical work.
DISSOCIATION OF O2 ON Fe(110)
Authors: WORTHY G. , COTTRELL C. , WIGHT A. , HODGSON A.
Published: November 2004

The initial sticking coefficient for dissociative chemisorption of O 2 on Fe(110) has been measured as a function of translational energy, incidence angle, and surface temperature. Dissociation is activated at translational energies above 100 meV, with the sticking probability rising from 0.26 at low energy to >0.9 for energies above 400 meV. At low energies the sticking probability increases as the surface temperature and the normal component of the momentum are reduced, indicating dissociation proceeds via trapping into a molecular precursor state. The initial saturation coverage at room temperature, calibrated from the ordered LEED phases, is 2.2 monolayers with both the saturation coverage and the uptake kinetics being sensitive to the surface temperature.
HOMOEPITAXIAL GROWTH ON Cu(111) PROBED BY HELIUM ATOM SCATTERING
Authors: DASTOOR P.C. , ELLIS J. , REICHMUTH A. , BULLMAN H. , HOLST B. , ALLISON W.
Published: November 2004

The homoepitaxial growth of Cu(111) has been investigated using specular helium atom scattering. Between 400 and 110 K the growth mode gradually changes from step flow at the higher temperatures to multilayer formation at low temperatures. Layerwise growth is not observed for any of the evaporation rates or substrate temperatures investigated, indicating a low diffusion rate across step edges. By lightly sputtering the surface, the density of growth nuclei and hence of step edges can be increased and a more layerwise growth mode results from the improved interlayer mass transport.
A SYNCHROTRON RADIATION STUDY OF ELECTRONIC AND MAGNETIC PROPERTIES OF SUPPORTED ULTRASMALL MANGANESE PARTICLES
Authors: KEEN A.M. , BAKER S.H. , BINNS C.R. , MOZLEY S.N. , NORRIS C. , DERBYSHIRE H.S.
Published: November 2004

We present a synchrotron radiation study of the electronic and magnetic properties of bulk Mn and ultrasmall Mn particles supported on graphite substrates. The Mn was deposited by thermal evaporation under ultrahigh vacuum conditions. The average particle size was determined from measurements of the (soft) X-ray reflectivity as a function of photon energy. Short-range magnetic order (SRMO) in the Mn samples was monitored with spin-polarised photoelectron diffraction (SPPED). An increase, relative to bulk Mn, in the peak asymmetry of the Mn 3p photoemission spectra for the Mn particles indicates either an increased density of states near the Fermi level or a less efficient screening of the core hole by the valence electrons.
ON STRUCTURAL EFFECTS IN ALKALI-OXYGEN COADSORPTION SYSTEMS
Authors: MURRAY S.J. , McGRATH R. , DIEHL R.D.
Published: November 2004

Available work function data and LEED data for alkali-oxygen transition metal coadsorption systems are summarised. The systems may be categorised as one of two types based on their work function behavior. A decrease in work function upon oxygen adsorption appears to be a necessary (but not sufficient) indicator for ordering of the overlayer. Available structural determinations [including our recent SPA-LEED/STM work on K–O/Ni(100)-(3×3)] are consistent with current models of work function behavior.
ACTIVATED ADSORPTION OF CO2 ON PURE AND PROMOTED NOBLE METAL SURFACES OBSERVED WITH RAMAN SPECTROSCOPY
Authors: AKEMANN W. , OTTO A.
Published: November 2004

The adsorption of CO 2 to surfaces of pure and promoted noble metal films is investigated at 40 K using surface-enhanced Raman spectroscopy (SERS). The data indicate nonactivated adsorption on silver and gold, activated adsorption on potassium and a coexistence of activated and nonactivated adsorption on copper and potassium-doped silver. The activated species is identified to be a [Formula: see text] surface anion.
THE SURFACE STRUCTURE OF A LOW Pd Cu/Pd-(110) CRYSTAL ALLOY
Authors: BOWKER M. , NEWTON M. , FRANCIS S.M. , GLEESON M. , BARNES C.
Published: November 2004

X-ray photoelectron diffraction studies of this alloy surface have been carried out and indicate that there is a significant expansion of the lattice in the near-surface region due to the high concentration of Pd in layer 2. Preliminary single scattering calculations lend support to this proposal for the surface structure, and place this expansion in the subsurface mainly between layers 2 and 3.
TEMPERATURE-DEPENDENT GROWTH OF THE Na/GaP(110) INTERFACE
Authors: EVANS D.A. , BAILEY P. , THORNTON J.M.C , D'ADDATO S.
Published: November 2004

The adsorption of Na onto GaP(110) surfaces is markedly different when the substrate is held below 120 K and above 140 K. At 120 K, the development of core and valence level photoelectron emission spectra is consistent with charge transfer between the alkali metal and the surface atoms of a chemically undisrupted substrate. However, at 140 K, similar measurements show very different spectral changes, resembling more closely a reactive interface, involving interaction between the Na and bulk GaP atoms.
INTERACTION AND REACTION OF CARBON MONOXIDE AND OXYGEN ON Ru(100) AND Ru(100)-Pd
Authors: POULSTON STEPHEN , TIKHOV MINTCHO , LAMBERT RICHARD M.
Published: November 2004

The behavior of coadsorbed CO and oxygen on Ru(100) is quite different from that observed on the other principal faces of the metal. LEED data show that the two adsorbates coexist in separate domains and that mutual compression effects result in formation of high-density oxygen structures which are not accessible by oxygen chemisorption alone. These domains are catalytically inert under UHV conditions, although TDS and ΔΦ results show that they significantly influence each other. The presence of Pd triggers CO 2 formation at a threshold metal coverage of 2 ML, full Pd activity being recovered at ~6 ML.
INFLUENCE OF ION IMPLANTATION ON THE SURFACE CHARACTERISTICS OF POLYCRYSTALLINE CdS LAYERS
Authors: AL-ACHKAR M. , SCOTT C.G.
Published: November 2004

PN-heterojunction type solar cells have been fabricated by immersing n-type polycrystalline CdS films in a solution containing copper ions, to form a p-type Cu 2 S layer over the CdS surface. The efficiency and stability of these devices have been found to be very dependent on the grain structure of the initial CdS layers but by the use of ion implantation to modify the structure of the CdS surface significant improvements in cell characteristics have been obtained. Evidence is provided to show that this improvement can be attributed to a reduction in the effective junction area of the cells.
ADSORPTION HEATS AND STICKING PROBABILITIES FOR CO ON POTASSIUM-PREDOSED Ni{110}
Authors: WARTNABY C.E. , STUCKLESS J.T. , KING D.A.
Published: November 2004

Simultaneously measured sticking probability and heat of adsorption data are presented for the initial reaction of CO with potassium-precovered Ni{110}. Two distinct regimes are observed which correspond with the potassium-affected structure of the surface: for less than 0.35 ML of potassium, the nickel substrate undergoes a missing-row reconstruction, while above this coverage the reconstruction is lifted. On the missing-row structure, the CO sticking probability remains high and the heat of adsorption is increased by only 40 kJ mol –1 compared with the clean surface value, to 170 kJ mol –1. On the high potassium coverage structure, the CO sticking probability is dramatically reduced but the CO heat of adsorption is further increased to 250 kJ mol –1.
CHARACTERISATION OF INTERFACIAL BONDING AND PHOTOCHEMISTRY IN SELF-ASSEMBLED THIOL MONOLAYERS ON GOLD USING NEXAFS AND ARUPS
Authors: RIELEY H. , PRICE N.J. , WHITE R.G. , BLYTH R.I.R. , HÅKANSSON L. , ROBINSON A.W.
Published: November 2004

S K-edge near-edge X-ray absorption fine structure (NEXAFS) has been used to establish the oxidation state of S in self-assembled monolayers (SAMs) of heptane and octane thiols, RSH [ R=CH 3( CH 2)n, n=6, 7] and the analogous halo-alkane disulphides, [(X RS )2, X= Cl , Br ] derivatised ex situ on Au foil. We find that the initially prepared surface thiolate species (RS–) is photo-oxidised by X-radiation, in the presence of coadsorbed oxygen, to sulphonate [Formula: see text]. Angle-resolved UV photoemission (ARUPS) has been used to further characterise the nature of the S-Au interaction in these SAMs following their preparation in UHV on Au(111). The ARUPS results suggest the involvement of the Au d-bands in the S-Au bond.
Recent Insights into the Structure and Mechanism of the Sodium Pump
Authors: Horisberger J.-D.
Published: November 2004

The sodium pump (or Na-K-ATPase) is essential to the function of animal cells. Publication of the related calcium pump (SERCA) structure together with several recent results from a variety of approaches allow us to propose a mechanistic model to answer the question: “How does the sodium pump pump?”
Common Cues in Vascular and Axon Guidance
Authors: Serini Guido , Bussolino Federico
Published: November 2004

Blood vessels and nerves are structured in architecturally similar organ systems and show functional relationships. Indeed, vascular and neuronal cells are guided in their journey throughout the body by the same attractive and repulsive factors that respectively activate and inhibit the function of integrin-adhesive receptors.
Directed Vascular Expression of Human Cysteinyl Leukotriene 2 Receptor Modulates Endothelial Permeability and Systemic Blood Pressure
Authors: Hui Yiqun , Cheng Yan , Smalera Isabella , Jian Wenying , Goldhahn Lawrence , FitzGerald Garret A. , Funk Colin D.
Published: November 2004

Background—

The proinflammatory and vascular actions of cysteinyl leukotrienes (CysLTs) are mediated by 2 receptors: cysteinyl leukotriene 1 receptor (CysLT
1
R) and cysteinyl leukotriene 2 receptor (CysLT
2
R). However, the distinct contribution of CysLT
2
R to the vascular actions of CysLTs has not been addressed.

Methods and Results—

We generated an endothelial cell–specific human CysLT
2
R (EC-hCysLT
2
R) transgenic (TG) mouse model using the Tie2 promoter/enhancer. Strong expression of hCysLT
2
R in TG lung and endothelial cells, detected by real-time polymerase chain reaction, markedly enhanced CysLT-stimulated intracellular calcium mobilization compared with endogenous expression in cells from nontransgenic mice. The permeability response to exogenous LTC
4
and to endogenous CysLTs evoked by passive cutaneous anaphylaxis was augmented in TG mice. The rapid, systemic pressor response to intravenous LTC
4
was also diminished in TG mice coincidentally with augmented production of nitric oxide.

Conclusions—

The development of EC-hCysLT
2
R mice has permitted detection of distinct vascular effects of CysLTs, which can be mediated via the CysLT
2
R in vivo.
Modeling the Unsaturated Flow in Liquid Composite Molding Processes: A Review and Some Thoughts
Authors: Pillai Krishna M.
Published: November 2004

The liquid composite molding (LCM) processes for manufacturing polymer composites involve injecting a thermoset resin into a fiber-packed mold cavity. Very often, the fiber preform behind the resin front is partially saturated during the mold-filling process in LCM, giving rise to an unsaturated flow in that region. This paper first discusses the role of dual-scale porous media in inducing unsaturated flow in certain directional (woven, stitched, or braided) mats due to the delayed impregnation of tows. The approach of using a sink term in the mass balance equation is compared with the traditional approach of using unsaturated permeability for modeling unsaturated flow in dual-scale directional mats. Later, the relation of unsaturated flow with the phenomenon of bubble formation and migration is discussed. The lack of connection between the unsaturated flow research on the one hand, and the bubble creation and migration research on the other, is highlighted next. A few suggestions are offered on related topics, including the modeling of bubble motion, and the need for accurate experiments in unsaturated flow.
Low-Velocity Impact Response of Polyurethane Foam Composite Sandwich Structures
Authors: Sharma S. C. , Narasimha Murthy H. N. , Krishna M.
Published: November 2004

Low-velocity instrumented impact tests were carried out on sandwich panels made of glass fiber-reinforced plastic facesheets and polyurethane foam core. The tests were carried out using a drop weight instrumented impact tester, connected to a data acquisition system. Four different types of sandwich samples using polyester/e-glass and epoxy/e-glass facesheet materials and polyurethane foam were considered for investigation. Two different face sheet materials were chosen to experimentally examine the effect of their elastic modulus on the impact response of the sandwich structures. The data acquisition system records the impact data such as impact force, penetration time and depth of penetration, and plots impact force versus depth of penetration and penetration time versus depth of penetration curves. From the recorded data the impact parameters such as maximum impact force, penetration time and depth of penetration versus impact energy were plotted to study the impact behavior. The results show that higher impact energy is required to break the epoxy/e-glass facesheet and backsheet sandwich specimens than other types of specimens examined. The impact damage caused to the facesheet, the core and the backsheet were thoroughly studied experimentally and the extent of damage caused to the facesheets and the core were also compared by finite element analyses.
Stress Analysis of an Orthotropic Rotating Disc under Thermal Loading
Authors: Callioglu Hasan
Published: November 2004

In this study, a thermal stress analysis on a glass-fiber/epoxy orthotropic rotating hollow discs is investigated. A closed form solution is performed using polynomials under some considerations. The temperature distribution is chosen to vary parabolically from inner surface to outer surface along the radial sections. The distributions of the tangential and radial stress components are given in figures. When the temperature is increased further, the tangential stress component decreases at the inner surface, whereas increases at the outer surface, and radial stress component are reduced. The radial displacement is calculated analytically and has a higher value at the outer surface than at the inner surface.
Low Velocity Impact Study of Laminate Composites with Mode I Crack Using Dynamic Optical Caustics
Authors: Yao Xue Feng , Xu Wei , Jin Guan Chang , Yeh Hsien Yang
Published: November 2004

The dynamic evolutions of stress singularities at mode I crack tip in laminate composites are studied by combining optical caustic with high-speed schardin camera. Theoretical caustics and initial curve for two different fiber laminate composites are simulated. Some characteristics of stress singularity at crack tip are analyzed. On the other hand, the generation and the subsequent evolution of dynamic failure around the crack tip are visualized by the optical shadow spots. The characteristic sizes of local stress concentration are extracted and the stress intensity factors at crack tip are determined. The local response and failure evolution mechanism of laminated composite after impact are analyzed by means of a series of optical caustic image and the deformation of composites.
Predicting Elastic Constants of 2D-Braided Fiber Rigid and Elastomeric–Polymeric Matrix Composites
Authors: Carey J. , Fahim A. , Munro M.
Published: November 2004

In a previous work, an analytical model based on Classical Laminate Plate Theory (CLPT) was developed to predict the braid elastic constants (Ex, Ey, Gxy and xy) of closed-mesh 2Dbraided fiber composite. In this work, the sensitivity of the braid elastic constants to composite constituent elastic constants was evaluated. The torsion of thin-walled tubes was used to experimentally obtain the braid shear modulus. The results predicted by the model are in good agreement with other models and with experimental results for Ex and Gxy of Kevlar 49 fiber-braided tubes with both rigid epoxy and elastomeric polyurethane resin matrices.
Mental Disorder that Afflicted King David the Great
Authors: Ben-Noun Liubov (Louba)
Published: November 2004

This research uses the tools of modern medical science to study ancient descriptions of the symptoms suffered by King David. Biblical texts were examined, with a close study of verses relating to the mental disorder that afflicted King David, the second and greatest King of Israel, who ruled more than3525 years ago. We include no commentaries, but refer only to the words of the Bible exactly as written. Evaluation of the passages referring to King David indicates that he was afflicted by some mental disorder, and among the many possibilities major depression, dysthymia and minor depression are the most likely. Of these diagnoses, major depression seems the most acceptable. This report suggests that the roots of contemporary psychiatry can be traced back to Biblical times.
Dworkin’s auction
Authors: Heath Joseph
Published: November 2004

Ronald Dworkin’s argument for resource egalitarianism has as its centerpiece a thought experiment involving a group of shipwreck survivors washed ashore on an uninhabited island, who decide to divide up all of the resources on the island equally using a competitive auction. Unfortunately, Dworkin misunderstands how the auction mechanism works, and so misinterprets its significance for egalitarian political philosophy. First, he makes it seem as though there is a conceptual connection between the ‘envy-freeness’ standard and the auction, when in fact there is none. Second, he fails to appreciate how idealized the conditions are that must be satisfied in order for his results to obtain. This leads him to draw practical conclusions from the thought experiment that do not follow, such as his claim that the principle of equality generates a presumption in favor of the market as a mechanism for the distribution of resources. The result is that Dworkin saddles resource egalitarianism with a set of commitments that are, in fact, inessential to that view.
Add-on therapy options in asthma not adequately controlled by inhaled corticosteroids: a comprehensive review
Authors: Kankaanranta Hannu , Lahdensuo Aarne , Moilanen Eeva , Barnes Peter J
Published: November 2004

Many patients with persistent asthma can be controlled with inhaled corticosteroids (ICS). However, a considerable proportion of patients remain symptomatic, despite the use of ICS. We present systematically evidence that supports the different treatment options. A literature search was made of Medline/PubMed to identify randomised and blinded trials. To demonstrate the benefit that can be obtained by increasing the dose of ICS, dose-response studies with at least three different ICS doses were identified. To demonstrate whether more benefit can be obtained by adding long-acting β2-agonist (LABA), leukotriene antagonist (LTRA) or theophylline than by increasing the dose of ICS, studies comparing these options were identified. Thirdly, studies comparing the different "add-on" options were identified. The addition of a LABA is more effective than increasing the dose of ICS in improving asthma control. By increasing the dose of ICS, clinical improvement is likely to be of small magnitude. Addition of a LTRA or theophylline to the treatment regimen appears to be equivalent to doubling the dose of ICS. Addition of a LABA seems to be superior to an LTRA in improving lung function. However, addition of LABA and LTRA may be equal with respect to asthma exacerbations. However, more and longer studies are needed to better clarify the role of LTRAs and theophylline as add-on therapies.
Damage control in orthopaedic trauma
Authors: Grannum S , Gardner A , Porter K
Published: November 2004

The last century has seen great strides in the care of the polytrauma patient. Prior to the 1950s, routine operative stabilization of long bone fractures was not performed. With the advent of modern methods of fracture fixation the philosophy of early total care arrived and all fractures were operatively fixed at an early stage. Further understanding of the inflammatory response in trauma has now led to the concept of damage control orthopaedics. The aim of this review is to highlight this philosophy and its use in the polytrauma patient.
The emotional and behavioural consequences of traumatic brain injury
Authors: Gouick Jo , Gentleman Douglas
Published: November 2004

Recent published articles on emotional and behavioural consequences of trau matic brain injury (TBI) are reviewed. Database searches (Medline, Embase Psychiatry, CINAHL) for key terms (head injury, brain injury, adjustment, adapta tion, psychological, social, emotion, mood disorder) are used to identify relevant articles. The range of clinical problems reviewed include depression and anxiety, post-traumatic stress symptoms, apathy and anger. Comment is made on adjust ment to the effects of brain injury, including family adjustment and changes in presentation over the time course of recovery. Conclusions are drawn recognizing the importance of treatment for the psychological effects of TBI.
Trauma in pregnancy: anatomical and physiological considerations
Authors: McAuley Duncan J
Published: November 2004

Management of a pregnant trauma victim is a relatively rare but stressful event, not least due to the need to consider two patients. Initial management by a trauma team should follow a structured approach applicable to all trauma patients, combined with knowledge of the specific problems encountered in pregnancy. This review outlines important anatomical and physiological changes that occur during pregnancy and their relevance to initial assessment and treatment. It discusses the epidemiology of trauma in pregnancy, the presentation and manage ment of specific problems and the methods of fetal assessment.
Effect of Addition of Adjuvant Paclitaxel on Radiotherapy Delivery and Locoregional Control of Node-Positive Breast Cancer: Cancer and Leukemia Group B 9344
Authors: Sartor Carolyn I. , Peterson Bercedis L. , Woolf Susan , FitzGerald Thomas J. , Laurie Frances , Turrisi Andrew J. , Bogart Jeff , Henderson I. Craig , Norton Larry
Published: November 2004

Purpose

We compared radiotherapy (RT) delivery and locoregional control in patients with node-positive breast cancer randomly assigned on Cancer and Leukemia Group B 9344 to receive adjuvant doxorubicin/cyclophosphamide (AC) with patients assigned to receive AC followed by paclitaxel (AC+T).

Methods

Eligible patients were randomly assigned to receive adjuvant AC versus AC+T chemotherapy. RT was required if breast-conserving surgery was performed but was elective after mastectomy. Information about RT delivery was retrospectively collected. Cumulative incidence of locoregional recurrence (LRR), use of elective RT, and RT delivery were compared between treatment arms.

Results

For patients treated with breast-conserving surgery and RT, the 5-year cumulative incidence of isolated LRR was 9.7% in the AC arm and 3.7% in the AC+T arm (P = .04) and of LRR as any component of failure was 12.9% versus 6.1%, respectively (P = .04). Although LRR rates in patients who did not receive postmastectomy RT were lower in the AC+T arm, the difference was not statistically significant. Despite the lack of protocol guidelines, RT use did not differ between arms, nor did RT dose, treatment interruption, or completion.

Conclusion

Despite the delay to RT during additional chemotherapy, adjuvant AC+T afforded better local control than AC alone in patients treated with breast-conserving therapy. Addition of paclitaxel did not adversely affect delivery or ability to tolerate RT, as indicated by similar rates of completion of timely, full-dose RT between arms.
Study of fluid velocity characteristics in stirred solid-liquid suspensions with a refractive index matching technique
Authors: Micheletti M , Yianneskis M
Published: November 2004

A refractive index matching laser Doppler anemometry technique was applied to a solid-liquid suspension in order to measure the continuous phase velocity in the impeller stream of a mixing vessel stirred by a Rushton turbine. Monodispersed, neutrally buoyant and impurity-free particles were used up to 2 per cent volumetric concentration. A significant influence of the dispersed phase on the liquid mean and turbulent flow field was found only near the impeller disk plane, at radial locations close to the blade tip, where both the radial mean and fluctuating velocity components were suppressed by the presence of the solid phase. The fluid velocity variation with angular position was also investigated. A locally high concentration of particles in front of the blades and in the trailing vortices area is suggested as the reason for the modification of the flow observed.
Computational modelling of the unsaturated flow of liquid in heap leaching, using the results of column tests to calibrate the model
Authors: Sheikhzadeh G. A. , Mehrabian M. A. , Mansouri S. H. , Sarrafi A
Published: November 2004

Unsaturated flow of liquid in a bed of uniform and spherical ore particles is studied numerically and experimentally. An unsteady and two-dimensional model is developed on the basis of the mass conservation equations of liquid phase in the bed and in the particles. The model equations are solved using a fully implicit finite difference method giving the distribution of the degree of saturation in the particles and in the bed and the vertical velocity of flow in the bed, as well as the effect of periodic infiltration on the above distributions. To calibrate the computational model, several column tests are performed using periodic infiltration of water on 40 cm high columns composed of ore having particles smaller than 25 mm. The numerical analysis shows that the results obtained from numerical modelling under the same operating conditions as used for column tests are in good agreement with those from experimental procedure, the degree of saturation of the bed and the time required to reach steady state conditions depend on the inflow of water and intrinsic permeability of the bed and the velocity fluctuations and the fluctuations of the degree of saturation in the bed depend on the inflow of water, period of infiltration, height and intrinsic permeability of the bed.
Finite element modelling of stretch-blow moulding of PET bottles using Buckley model: Plant tests and effects of process conditions and material parameters
Authors: Yang Z. J. , Harkin-Jones E. M. A. , Armstrong C. G. , Menary G. H.
Published: November 2004

Plant tests and finite element (FE) analyses of the injection stretch-blow moulding (ISBM) process of polyethylene terephthalate (PET) bottles have been carried out in this study with a view to optimizing preform designs and process conditions. Plant tests were carefully conducted at first to make bottles in a 330 ml mould from four preform designs under different process conditions. Both a digital handheld thermometer and a FLIR ThermoCAM Imager system were used to measure the initial preform temperature distributions (IPTDs). Comprehensive FE analyses using ABAQUS were then carried out to model the ISBM of these bottles, using a physically based model (Buckley model) to model the complex constitutive behaviour of PET. It was found that the numerical simulations often resulted in free blowing or over-thinning of the bottle bottoms when the measured IPTDs and process conditions were modelled. Parametric studies of the IPTDs, the pre-blowing pressure and the material parameters of the Buckley model were carried out. It was demonstrated that all of them had considerable effects on the effectiveness of FE modelling. In particular, the stress-strain relations modelled by the Buckley model were very sensitive to two parameters used to model the strain-stiffening behaviour. By carefully adjusting the material parameters and process conditions, successful simulations with excellent bottle thickness predictions were then achieved. It is concluded that the model parameters must be obtained by accurately testing the bottle-grade PET with similar process conditions to those in industrial ISBM so that the Buckley model can be confidently used to model the ISBM process. It is also found that good predictions of bottle wall thickness alone do not necessarily justify the numerical modelling. Validation of the deformation process may be equally important.