bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Particle Shape on Water-Free Mica ER Fluids
Authors: Duan Xiaodong , Luo Weili , Chen Hong , He Yuanjin
Published: August 2002

The yield stresses of the water-free mica ER fluid for different particle sizes and concentrations are investigated. For a certain particle size, there is an optimum concentration for maximum yield stress. We found that the larger the particle size, the smaller the optimum concentration. These new phenomena stem from the high shape anisotropy of the mica particle. A model based on electrical dipole interaction can qualitatively explain these phenomena.
Compressive Failure Mechanism and Impact Behavior of Unidirectional Carbon-Fiber/Vinyl Ester Composites
Authors: Yuan Jianming , Takeda Nobuo , Waas Anthony M.
Published: August 2002

Compressive failure of carbon fiber reinforced unidirectional vinyl ester composites (CFRP) under impact is studied experimentally and analytically. Both impact and quasi-static compressive tests are carried out for CFRP with Vf= 10% to 60%. Stress-stain curves at strain rates of 10-3 s-1 and 10-3 s-1 are obtained. The compressive strength increases under impact loading. As the fiber volume fraction increases, the failure mode changes from shear failure to kinking. The local stress fields in the fiber and matrix are analysed to illustrate the deformation and compressive failure mechanisms for unidirectional composites. Based on analysing the local matrix yield at the fiber-matrix interface due to shear stress concentration, the compressive strength is predicted. Assuming that shear failure and kinking occurs on the plane of the maximum shear strain in composites, the angle of the plane of the maximum shear strain is determined. The analytical model is utilised to explain the various experimental observations of CFRP failure, as well as GFRP failure reported in Reference [17], such as, the compressive strength, the failure mode, the effects of fiber volume fractions and strain rates.
Camouflage in the Non-Visible Region
Authors: Gupta K. K. , Nishkam A. , Kasturiya N.
Published: August 2002

To provide camouflage in non-visual range of spectrum, i.e., against NIR detection devices working in the range of 700–1500 nm, it becomes essential that camouflaging equipment should be painted/dyed with the pigments/dyes having NIR reflectance values similar to that of backgrounds in respective shades. Generally, the shades of vegetation and desert regions are confined to olive green, brown, deep brunswick green, light stone and dark stone colour, so it is required that IR reflectance values of pigment formulation must match with the IR reflectance values of these shades of the background vegetation or desert terrains.

An elaborate study has been carried out on these pigment formulations coated on cotton and nylon substrate materials. The study has brought out the reflectance trend of the formulations, role of each constituent pigment on the reflectance values and effect of dilution or concentration of pigment formulation on the reflectance properties. These studies would pave the way for preparation and optimization of various formulations with respect to IR reflectance values and their use for camouflage purpose in non-visual range of electromagnetic wave length.
Synthetic Hydrogels as Carriers in Antisense Therapy: Preliminary Evaluation of an Oligodeoxynucleotide Covalent Conjugate with a Copolymer of 1-Vinyl-2-Pyrrolidinone and 2-Hydroxyethyl Methacrylate
Authors: Lou Xia , Garrett Kerryn L. , Rakoczy Piroska E. , Chirila Traian V.
Published: August 2002

A major challenge of the antisense therapeutic strategies is the development of improved systems for the delivery of antisense oligodeoxynucleotides (AS ODNs) in order to enhance the cellular uptake, to assure a better efficiency in reaching the target tissue, and to provide sustained delivery over longer periods of time. Because the current methods for delivery (liposomes and cationic polymers) present somedisadvantages, the attention was directed toward the use of neutral polymers as carriers for the AS ODNs. Based on our previous work on synthetic hydrogels for vitreous substitution, we developed a poly[1-vinyl-2-pyrrolidinone- co-(2-hydroxyethyl methacrylate)] hydrogelas a potential carrier for AS ODNs. We have previously demonstrated that such hydrogels are not cytotoxic, and they may have growth-promoting effects on cultured fibroblasts. This copolymer also has the advantage of being injectable. In this study, a specific AS ODN was synthesized and then covalently bound to the copolymer via carbodiimide coupling method. The resulting conjugate was subjected to in vitro release experiments over 46 days in the presence of bovine vitreous humor. Compared with the control (no enzyme present), a significantamount of covalently bound ODN was released from the ODN-hydrogel conjugate, suggesting the possibility of using such systems for the sustained delivery of AS ODNs.
Effects of Pulsed Electric Field Processing on Apple and Pear Polyphenoloxidases
Authors: Giner J. , Gimeno V. , Barbosa-Cánovas G. V. , Martín O.
Published: August 2002

The feasibility of inhibiting polyphenoloxidase from apple and pear by pulsed electric field processing was evaluated. These treatments significantly lowered polyphenoloxidase activity of enzyme extracts from apple ( Golden deliciousvar.) and pear ( Blanquillavar.). Exponential decay pulses were generated by a laboratory scale electric pulse generator and applied in bipolar mode. Pulse duration was 0.02 ms and electric field intensities were up to 24.6 kV/cm. The temperature of samples never exceeded 15 ºC during pulsed electric field processing treatments. Polyphenoloxidase activities were reduced up to 3.15% and 38.0% initial value in apple extract at 24.6 kV/cm and pear extract at 22.3 kV/cm both for 6 ms total treatment time, respectively. Apple and pear polyphenoloxidase exposed to pulsed electric field processing diminishes their activities following first order kinetics. Rate constants ranged from 132 to 440 ms 1 for apple polyphenoloxidase, whereas for pear 1 and changed exponentially with the applied electric field intensity. Residual polyphenoloxidase activity was correlated to energy density by an exponential decay model.
HFC-245fa Spray Polyurethane Foam Systems Co-Blown with Water: A Quality, Cost Effective, Safe Substitute for HCFC-141b
Authors: Bogdan Mary , Williams David , Verbiest Paul
Published: August 2002

The effective use of insulation is key to energy conservation. The effectiveness of insulation is dependent upon many factors. In the case of rigid foam insulation a key factor is the blowing agent used. Industry evaluations have shown that HFC-245fa produces foams with the highest insulation value of any HCFC-141b alternative-blowing agent in the construction market.

Meeting the market needs is critical to the success of any new product. Today’s insulation specifiers are not only concerned about energy savings but also cost. Chemical and manufacturing changes can have a significant effect on product cost. The higher vapor pressure of HFC-245fa and its potential impact on packaging has also been a concern to the spray foam industry. This paper contains the latest results about the use of HFC-245fa foam systems co-blown with water, which meet the needs of the spray foam market. They are cost effective, produce foams with low k-factors, good physical properties, and can be stored and shipped in existing drums. This will allow applicators and manufacturers to safely use existing equipment without significant modifications or safety concerns.

HFC-245fa and water used as co-blowing agents provide a wide range of benefits in spray foam. Since less HFC-245fa is used, the vapor pressure is lower, and the cost of the system is reduced while improving the physical properties of the foam. There is however an increase in k-factor.

We have determined also that the addition of low levels of •-methyl styrene to a spray foam polyol blend lowers the vapor pressure of the polyol blend and enhances the k-factor of the foams produced. This allows the user to optimize k-factor while lowering the cost.

Data from laboratory evaluations of these blends are presented. This paper also includes a discussion of the cost of these blends from a chemical, manufacturing and performance perspective. We consider HFC-245fa/water co-blown spray foam to be a quality, cost effective and safe alternative to HCFC-141b blown foams in the future.
Micro-Mechanics of Fatigue Damage in Pb-Sn Solder Due to Vibration and Thermal Cycling
Authors: Dasgupta A. , Sharma P. , Upadhyayula K.
Published: August 2002

This paper presents a micro-mechanistic approach for modeling fatigue damage initiation due to cyclic plasticity and cyclic creep in eutectic Pb-Sn solder. The issue of damage evolution is deferred to a future paper. Fatigue damage model due to cyclic plasticity is modeled with dislocation mechanics. A conceptual framework is provided to quantify the influence of temperature on fatigue damage due to cyclic plasticity. Damage mechanics due to cyclic creep is modeled with a void nucleation model based on micro-structural stress fields. Micro-structural stress states are estimated under viscoplastic phenomena like grain boundary sliding and its blocking at second phase particles, and diffusional creep relaxation. A conceptual framework is provided to quantify the creep-fatigue damage due to thermo-mechanical cycling.
Microstructure and Mechanical Properties of Reaction Squeeze Cast Hybrid Al Matrix Composites
Authors: Son Changwook , Kim Ikwoo , Park Ikmin , Cho Kyung-Mox , Choi Ildong
Published: August 2002

Hybrid Al matrix composites reinforced with Kaowool ceramic fiber (Al2O3 · SiO2) and reaction formed intermetallic compound particles, starting compositions of (10%Al2O3 · SiO2 + 5%Ni)/Al and (10%Al2O3 · SiO2 + 5%TiO2)/Al were fabricated employing squeeze casting technique. Microstructures of the Al composites were examined, and the reactivity of Ni and TiO2 powders added to Kaowool short fiber preform with infiltrating molten Al, resulting products of Al3Ni and Al3Ti, during squeeze casting was analyzed. Hardness, strength (at 25 and 300°C) and wear resistance of the composites were characterized. To investigate the fracture behavior of the composites, in-situ fracture test was performed within SEM. The hybrid Al composites revealed the microstructure of uniformly distributed reinforcements (ceramic short fiber and reaction formed intermetallic compounds). Ni powder added hybrid Al composite achieved the highest hardness, strength and wear resistance among the composites. It was found that the strength drop at elevated temperature (300°C) is effectively reduced by hybridization with ceramic fiber and intermetallic compounds reinforced in Al. In-situ fracture observation demonstrated the fracture behavior of Ni powder added hybrid Al composite as microcrack initiated mainly by short fiber/ matrix interfacial debonding and the crack propagated through the cluster of intermetallic compound particles as loading is raised.
Liposomes: Applications in Medicine
Authors: Banerjee R.
Published: August 2002

Liposomes are spherical lipid bilayers from 50 nm to 1000 nm in diameter that serve as convenient delivery vehicles for biologically active compounds. The field of liposome research has expanded considerably over the last 30 years. It is now possible to engineer a wide range of liposomes varying in size, phospholipid composition and surface characteristics to suit the specific application for which they are intended. This paper gives an overview of the main advances in liposome research from a point of view of their applications in medicine. Aqueous contrast enhancing agents entrapped in liposomal carriers can be targeted to the liver and spleen and distinctions can be made between normal and tumorous tissue using computed tomography. Topical application of liposomes has great potential in dermatology. Liposomes have been used to deliver anticancer agents in order to reduce the toxic effects of the drugs when given alone or to increase the circulation time and effectiveness of the drugs. From the original concept of encapsulating hemoglobin in an inert shell, liposome-encapsulated hemoglobin (LEH) has evolved into a fluid proven to carry oxygen, capable of surviving for reasonable periods in the circulation and amenable to large-scale production. Liposomes may be used to target specific cells by attaching amino acid fragments such as antibodies or proteins or appropriate fragments that target specific receptor sites. Liposomal DNA delivery vectors and further enhancements in the forms of LPDI and LPDII are some of the safest and potentially most versatile transfer vectors used to date. DNA vaccination and improved efficiency of gene therapy are just a few of the upcoming applications of liposomes.
Numerical Simulation of Freezing and Melting in Porous Materials under the Consideration of the Coupled Heat and Moisture Transport
Authors: Haeupl Peter , Xu Yugong
Published: August 2002

A model for freezing and melting processes in capillary-porous media involving coupled heat and mass transfer is proposed in this paper. The model is essentially different from the famous Harlan model [1], which is commonly used in freezing soil science. According to the established model a computer code has been developed. The present results, obtained from the numerical calculation for different building constructions subjected to steady and unsteady boundary conditions, show that the established model can be successfully applied to numerically simulate the coupled heat and mass transfer in capillary-porous materials during freezing and melting as well as under frost-free conditions.
An Elastic-Plastic Stress Analysis in a Thermoplastic Composite Cantilever Beam Loaded Uniformly
Authors: Sayman Onur , Arslan Nurettin , Pihtili Hasim
Published: August 2002

In this study an elastic-plastic stress analysis is carried out on a steel fiber reinforced thermoplastic composite cantilever beam loaded uniformly at the upper surface. An analytical solution is found satisfying both the governing differential equation in two dimensional case and boundary conditions. In this solution, the intensity of the uniform force is chosen small, therefore the transversely normal stress component is neglected in comparison with the other stress components. The thermoplastic matrix is reinforced unidirectionally by steel fibers. The orientation angles of the fibers are chosen as 0°, 30°, 45°, 60° and 90°. The plastic region begins first at the upper surface of the beam for 30° and 45° orientation angles. However, it starts earlier at the lower surface for 60° orientation angle. The intensity of the normal residual stress component in the axial direction of the beam is maximum at the upper and/or lower surfaces in the beam. The intensity of the shear residual stress is maximum on or around the axial axis of the beam.
Effect of Strain Rate on the Near Crack Tip Behavior of a Particulate Composite
Authors: Max Yen S. C. , Liu C. T.
Published: August 2002

This paper presents experimental results regarding the crack propagation and strain field near the crack tip of a particulate composite material under high strain rates. The particulate composite material presently being studied is viscoelastic in nature, therefore, the characteristics of stress relaxation and redistribution near the vicinity of the crack tip are thought to be different under different loading rates. In addition, the strain field ahead of the crack tip is related to the evolution of the damage zone and the crack propagation rate. In particular, the size and shape of a damage zone can dominate the crack propagation process.
Determination of Dynamic Flexural and Shear Moduli of Thick Composite Beams Using Natural Frequencies
Authors: Ip K. H. , Tse P. C.
Published: August 2002

Based on natural frequencies, a simple and stable inverse calculation scheme for characterizing the dynamic flexural moduli, the dynamic in-plane shear modulus and the dynamic transverse shear modulus of thick fiber-reinforced composite beams is developed, and is verified by experimental testing. Expressions are derived for the errors in the characterized moduli to the geometry and material properties of the beam samples. The stability of the inverse scheme is validated by two finite element (FE) composite beam models. Impact modal tests are employed to obtain the flexural vibration frequencies of the free-free supported beam sample. The measured frequencies are subsequently used in the inverse scheme to tune the flexural and shear moduli of a Timoshenko beam model.
Readout Electronics Scheme in CMOS Technology for Integration with Analog Outputs from Integrated Smart Sensors
Authors: Srivastava A. , Prasanna S. V. , Ajmera P. K.
Published: August 2002

A digital readout electronics scheme in CMOS technology is described for integration with micro-electro-mechanical (MEM) sensors on the same chip. The readout circuit is general in nature and can be employed with a variety of analog sensors. The presented scheme in CMOS technology is fully integrable with the multiple sensor outputs either in a chain or an array format and is capable of detecting low analog output signals from a few mV to mV range. The CMOS circuit design is compatible with ±1.5V operation for low power consumption.
The Influence of Space Discretization on the Accuracy of Numerical Simulation of Heat and Moisture Transport in Porous Building Materials
Authors: Galbraith Graham H. , Li Jintang , Mclean R. Craig , Baker Paul H.
Published: August 2002

It is well recognised that the accuracy of numerical solutions for coupled heat and moisture transport problems are highly dependent upon the space discretization regime adopted. While a range of possible space discretization methods are outlined in the literature, most of the commonly available simulation models for heat and moisture transfer through building constructions adopt the oneway expansion method. As part of the process of developing a new simulation model based on the Control Volume technique, the Authors have conducted a range of computer simulations to study the influence of space discretization on modelling results. Comparisons between different space discretization methods are presented which show that the two-way expansion method generally produces the best solution. This method has now been adopted by the Authors and has the advantage of avoiding the need to use extremely fine grids even when modelling complex building structures.
Note. Reaction of Bacteria Associated with Fish Spoilage to Chemical and Physical Stress
Authors: Kirby R. , da Silva M. , Capell C. , Vaz-Pires P. , Gibbs P. , Davies A. , Jehanno D. , Thuault D. , Nychas G. , Luten J.
Published: August 2002

A cocktail made up of six bacteria isolated from fish was subjected to various heats (30 °C and 60 °C, 20 s) and chemical preservative stresses, alone and in combination. The chemical preservatives tested were potassium sorbate (PS, 1%), trisodium phosphate (TSP, 10%) and tetrasodium pyrophosphate (TSPP, 3%). Heating the bacteria at 60 °C for 20 s resulted in an average reduction of 2.0 log cfu/mL in the total number. The results showed amarked synergistic effect of heat treatment prior to chemical additives, especially for TSPP and sorbate; no significant effect was evident when chemicals were applied alone. The effect was increased by the application of chemical preservatives, before heating, in the decreasing order TSP, TSPP and sorbate; reductions obtained were more than 5.0, 4.0 and 3.0 log cfu/mL, respectively. The synergistic effect observed was dependent on the type of chemical additives used and also on the order of the treatments. Bacteria identified as Shewanella putrefaciens and Pseudomonas putida were more resistant to heat treatment and Brochothrix thermosphacta and Lactobacillus plantarum were more resistant to TSP treatment. These bacteria in the cocktail showed high sensitivity to combined TSP/heat treatment; bacterial cells identified as Enterobacter spp. were the most resistant to this treatment.
Fracture Behaviour of FRP Composite Laminates with an Embedded Elliptical Delamination at the Interface
Authors: Pradhan B. , Chakraborty D.
Published: August 2002

This study deals with the delamination initiation from an existing embed ded elliptical delamination at the interface of FRP composite laminates. A full 3D FE anal ysis has been performed to calculate the interlaminar stresses at the interface responsible for delamination. Concept of fracture mechanics has been used to calculate the components of strain energy release rates at the interface. An elliptical delamination has been simulated to be present at the interface of two sublaminates each consisting of several plies and the laminate has been subjected to a central concentrated transverse loading. Effects of impor tant factors like fiber orientation of the adjacent layers, laminate thickness and the aspect ratio of the elliptical delamination on strain energy release rate components have been stud ied. It has been observed that the strain energy release rates vary along the delamination front showing an anisotropic delamination. The magnitudes of strain energy release rate components depend upon the fiber orientation of the adjacent layers, laminate thickness and the aspect ratio of the delamination present at the interface.
COMPUTING WITH MEMBRANES (P SYSTEMS): A VARIANT
Authors: PĂUN GHEORGHE
Published: August 2002

Membrane Computing is a recently introduced area of Molecular Computing, where a computation takes place in a membrane structure where multisets of objects evolve according to given rules (they can also pass through membranes). The obtained computing models were called P systems. In basic variants of P systems, the use of objects evolution rules is regulated by a given priority relation; moreover, each membrane has a label and one can send objects to precise membranes, identified by their labels. We propose here a variant where we get rid of both there rather artificial (non-biochemical) features. Instead, we add to membranes and to objects an "electrical charge" and the objects are passed through membranes according to their charge. We prove that such systems are able to characterize the one-letter recursively enumerable languages (equivalently, the recursively enumerable sets of natural numbers), providing that an extra feature is considered: the membranes can be made thicker or thinner (also dissolved) and the communication through a membrane is possible only when its thickness is equal to 1. Several open problems are formulated.
CORRUGATED SURFACES AND A.C. SPECTRUM
Authors: JAKŠIĆ VOJKAN , LAST YORAM
Published: August 2002

We study spectral and scattering properties of the discrete Laplacian H on the half-space [Formula: see text] with boundary condition ψ(n, -1) = V (n) ψ (n, 0). We consider cases where V is a deterministic function and a random process on Zd. Let H0 be the Dirichlet Laplacian on [Formula: see text]. We show that the wave operators Ω± (H, H0) exist for all V, and in particular, that σ (H0)⊂ σ ac (H). We study when and where the wave operators are complete and the spectrum of H is purely absolutely continuous, and prove some optimal results. In particular, if V is a random process on a probability space (Ω, ℱ, P), such that the random variables V (n) are independent and have densities, we show that the spectrum of H on σ (H0) is purely absolutely continuous P-a.s. If in addition lim |V(n)| = ∞ P-a.s., we show that the wave operators Ω± (H, H0) are complete on σ (H0) P-a.s.
REPRESENTATIONS OF THE HOMOTOPY SURFACE CATEGORY OF A SIMPLY CONNECTED SPACE
Authors: BRIGHTWELL MARK , TURNER PAUL
Published: August 2002

We discuss the homotopy surface category of a space which generalizes the 1+1-dimensional cobordism category of circles and surfaces to the situation where one introduces a background space. We explain how for a simply connected background space, monoidal functors from this category to vector spaces can be interpreted in terms of Frobenius algebras with additional structure.
FIRST STAGE OF THE FORMATION OF SILVER THIN FILMS ON THE As-PASSIVATED Si(111)-(1×1) SURFACE
Authors: BONNET J. E. , MARTIN M. G. , AVILA J. , ROCA L. , ASENSIO M. C.
Published: August 2002

The As-terminated Si surface has an ideally flat monolayer of As atoms at the outermost layer, showing a nonreconstructed (1×1) symmetry with one extra valence electron on each As atom, and setting a passivation, on the silicon surface, remarkable for its stablity up to temperatures above 600°C and under Ag deposition. Angle-resolved photoelectron spectroscopy (ARUPS) of valence bands in the main Brillouin zone directions of the As–Si(111) surface, and X-ray photoelectron diffraction (XPD), recorded with the LURE synchrotron light, provide the principal results presented in this work. No arsenic diffusion into the metallic overlayer is detected by photoemission, in a wide range of temperatures, proving the stability of the Ag/As–Si(111) interface, and allowing a first study of the structural and electronic properties of this flat interface. The formation of the silver–metal films on the semiconductor surface has been investigated, in particular the growth mode in the one-monolayer range and the building of the semiconductor–metal interface, and the evolution of the film during the silver deposition up to a few monolayers.
THERMAL DECAY OF ISOLATED SINGLE SILICON MOUNDS ON Si(111) SURFACES
Authors: ICHIMIYA A. , HAYASHI K.
Published: August 2002

Isolated three-dimensional (3D) silicon mounds on the Si (111)(7×7) surface have been produced using the tip of a scanning tunneling microscope (STM) at temperatures between 700 K and 750 K. Thermal relaxation processes of the mounds have been investigated by a temperature-variable STM. The 3D mounds formed by the STM tip are like pyramids with certain facets for both surfaces. The indices of the main facets of the mounds on the Si (111) surface are {311}, and those of the small facets are {221} or {331}. Two types of pyramids are produced on the Si (111). The pyramids with a production probability of 75% are normal stacking at the interface between the mound and the substrate, and are called type U. For mounds with a production probability of 25% which are in the twin relation of the type U mounds, there is a stacking fault at the interface, and they are called type F. The formation energy of the stacking fault is estimated from the ratio of the production probability as 4.7 meV/Å2. The decay rate of the type F mounds is about three times larger than that of the type U ones. During decomposition of the type U mounds, the facets of the pyramid are split into two parts. For the type F mounds, the pyramids decay nearly layer by layer without splitting of the facets and step bunching.
INTERACTIONS BETWEEN ADSORBED MOLECULES ON METAL SURFACES
Authors: KAWAI MAKI , KATO HIROYUKI
Published: August 2002

The tilted geometry of CO adsorbed on Pd(110) is identified using high-resolution electron energy-loss spectroscopy (HREELS), based on the observation of hindered rotational vibrations in the dipole-scattering spectra. With increasing coverage, the orientation of CO switches from the upright geometry to the tilted geometry, first along the Pd row and then perpendicular to the row. The dispersion of hindered translational modes of CO molecules in the (2×1)p2mg structure on Pd(110) clearly reflects a short-range interaction between the CO molecules adsorbed at the nearest-neighbor sites. From the analysis of the distinctive dispersion, a strong repulsive force constant is obtained, i.e. 10.5±1.5 N/m, which quantitatively asserts that the tilted CO is formed by the steric repulsion between the nearest-neighbor molecules.
INSTABILITIES OF PERMEABLE STEPS INDUCED BY THE DRIFT OF ADATOMS
Authors: SATO MASAHIDE , UWAHA MAKIO , SAITO YUKIO
Published: August 2002

We study the effect of permeability on the two types of step instabilities, bunching and wandering. When the step is permeable for adatom diffusion, the wandering instability occurs with step-down drift and the bunching instability occurs with step-up drift. In contrast, when the step is impermeable for adatom diffusion, both the wandering and the bunching instabilities occur with step-down drift. We derive the linear amplification rates of step fluctuation and the critical drift velocities to induce the instabilities. The results of the linear analysis are tested by Monte Carlo simulation.
ON THE ROLE OF KINKS AND STRAIN IN HETEROEPITAXIAL GROWTH: AN STM STUDY
Authors: LUNDGREN E. , SCHMID M. , LEONARDELLI G. , HAMMERSCHMID A. , STANKA B. , VARGA P.
Published: August 2002

Interlayer diffusion of Co over steps of vacancy islands on the Pt(111) surface as studied by scanning tunneling microscopy is presented. It is demonstrated that Co atoms descend Pt steps by an exchange diffusion process at the step edge with the Pt atoms. Further, the exchange diffusion process is observed to occur at the corners (kinks) of the vacancy islands. The importance of kinks concerning whether the growth mode of a heteropitaxial film is two-dimensional or three-dimensional is demonstrated for the case of thin Co films on Pt(111). We argue that the strain in the Co film is to a large extent responsible for the kink formation.
METACARPAL AND PROXIMAL PHALANGEAL FRACTURES — FIXATION WITH MULTIPLE INTRAMEDULLARY KIRSCHNER WIRES
Authors: Liew Kian Hwa , Chan Beng Kuen , Low Cheng Ooi
Published: August 2002

The use of intramedullary wires for fixation of fractures of the metacarpal and proximal phalanx in our hospital was reviewed. Twenty-six patients with 26 metacarpal fractures and four proximal phalangeal fractures were treated using this technique from 1993 to 1998. After a minimal follow-up of nine months, all the patients were assessed clinically and radiologically. All fractures proceeded to bony union at an average of 5.7 weeks (range four to eight weeks). With this simple and minimally invasive technique, most of these patients required very short hospital stay and were able to start mobilisation relatively early. The general outcome was good hand function with few complications.
ON A CLASS OF NASH EQUILIBRIA WITH MEMORY STRATEGIES FOR NONZERO-SUM DIFFERENTIAL GAMES
Authors: COULOMB JEAN MICHEL , GAITSGORY VLADIMIR
Published: August 2002

A two-player nonzero-sum differential game is considered. Given a pair of threat payoff functions, we characterise a set of pairs of acceptable feedback controls. Any such pair induces a history-dependent Nash δ-equilibrium as follows: the players agree to use the acceptable controls unless one of them deviates. If this happens, a feedback control punishment is implemented. The problem of finding a pair of "acceptable" controls is significantly simpler than the problem of finding a feedback control Nash equilibrium. Moreover, the former may have a solution in case the latter does not. In addition, if there is a feedback control Nash equilibrium, then our technique gives a subgame perfect Nash δ-equilibrium that might improve the payoff function for at least one player.
REPEATED PLAY AND NEWTON'S METHOD
Authors: FLÅM SJUR DIDRIK
Published: August 2002

Motivated by repeated play of non-cooperative games, we study equation solving undertaken in parallel by several non-communicating agents, each dealing with his own block of variables. The process is akin to Newton's method in using derivative information. It does, however, proceed without matrix inversion and dispenses with the need to exchange information between various blocks.
The cytochrome P4503A4 inhibitor clarithromycin increases the plasma concentrations and effects of repaglinide
Authors: Niemi Mikko , Neuvonen Pertti J. , Kivistö Kari T.
Published: August 2002

Objective

Our objective was to study the effects of the macrolide antibiotic clarithromycin on the pharmacokinetics and pharmacodynamics of repaglinide, a novel short‐acting antidiabetic drug.

Methods

In a randomized, double‐blind, 2‐phase crossover study, 9 healthy volunteers were treated for 4 days with 250 mg oral clarithromycin or placebo twice daily. On day 5 they received a single dose of 250 mg clarithromycin or placebo, and 1 hour later a single dose of 0.25 mg repaglinide was given orally. Plasma repaglinide, serum insulin, and blood glucose concentrations were measured up to 7 hours.

Results

Clarithromycin increased the mean total area under the concentration‐time curve of repaglinide by 40% (P < .0001) and the peak plasma concentration by 67% (P < .005) compared with placebo. The mean elimination half‐life of repaglinide was prolonged from 1.4 to 1.7 hours (P < .05) by clarithromycin. Clarithromycin increased the mean incremental area under the concentration‐time curve from 0 to 3 hours of serum insulin by 51% (P < .05) and the maximum increase in the serum insulin concentration by 61% (P < .01) compared with placebo. No statistically significant differences were found in the blood glucose concentrations between the placebo and clarithromycin phases.

Conclusions

Even low doses of the cytochrome P4503A4 (CYP3A4) inhibitor clarithromycin increase the plasma concentrations and effects of repaglinide. Concomitant use of clarithromycin or other potent inhibitors of CYP3A4 with repaglinide may enhance its blood glucose–lowering effect and increase the risk of hypoglycemia.

Clinical Pharmacology & Therapeutics (2001) 70, 58–65; doi: 10.1067/mcp.2001.116511
Whither Partnership Governance in Northern Ireland?
Authors: Greer Jonathan
Published: August 2002

Although partnerships are emerging as a central feature in governance arrangements in advanced capitalist societies, much discussion has taken place on the value and effectiveness of the approach. In recent years this debate has come to the fore in Northern Ireland, as a plethora of partnerships have been increasingly applied across a wide range of different government programmes at different levels of governance. Using a map of partnership arrangements in Northern Ireland, the author examines three case studies with a view to analysing the value and importance of partnership and assessing the activities that they do best. From this analysis, the author then discusses the future of partnership governance, outlines a number of areas for new research, and presents an agenda for development. As the case studies suggest that too much emphasis has been placed on developing a ‘process’, to the detriment of product outcomes, it is argued that partnerships need to adopt a dual approach to development by combining an inclusive process with greater strategic focus. At the regional level, however, a partnership framework is needed to facilitate coordination, reduce duplication, and improve understanding between partnerships, and between partnerships, local authorities, and government departments. Moreover, by adopting an inclusive approach, a partnership framework has the potential to provide a voice for the socially and politically excluded and to encourage participative planning and pluralist policymaking.
Tackling the Participation of the Unemployed in Paid Informal Work: A Critical Evaluation of the Deterrence Approach
Authors: Williams Colin C
Published: August 2002

In this paper I evaluate critically the use of deterrence to tackle the participation of the unemployed in paid informal work. On the basis of the assumption that the paid informal work of the unemployed is low-paid employment conducted for unadulterated economic reasons, the aim is to deter these rational economic actors by ensuring that the expected cost of being caught and punished is greater than the benefit of participating in such activity. Using structured interviews with the unemployed in UK lower income urban neighbourhoods, however, I found that pure economic motivations do not predominate when the unemployed participate in this work. Instead, such work is principally used to help out others, or to cement or forge social networks, or both. In consequence, I argue that there is a need to couple deterrence with the provision of alternative coping mechanisms in order to eradicate paid informal work. I conclude by proposing several policy initiatives that could act as a substitute for such work.
Environmental Resources, Property Regimes, and Efficiency
Authors: Vatn Arild
Published: August 2002

Why are certain property regimes preferred? They cannot be chosen on the basis of efficiency considerations alone, as what is efficient depends on the institutional structures themselves and the interests they defend. The author highlights some important distinctions between various property regimes: whereas categories like private, common, and state property all may imply some degree of co – ownership and overlap along some dimensions, the logic of each system, ideally defined, may be quite distinct. The author shows that there is nothing inherent in a resource that demands a certain regime. Property regimes are social constructs and must be defended by judgment, not by necessity. The author demonstrates that the main role of property regimes is to defend certain interests. Furthermore, they seem to influence which interests are formed or become activated. The preferences which form the basis for efficiency evaluations are thus dependent upon the chosen system. In this way, technically oriented evaluations like cost – benefit analysis are caught in severe circularities. The implication of this for policy is that the evaluation of regimes implies taking a stand concerning what we want to become, both as individuals and as a society.
When Texture Takes Precedence over Motion in Depth Perception
Authors: O'Brien Justin , Johnston Alan
Published: August 2002

Both texture and motion can be strong cues to depth, and estimating slant from texture cues can be considered analogous to calculating slant from motion parallax (Malik and Rosenholtz 1994, report UCB/CSD 93/775, University of California, Berkeley, CA). A series of experiments was conducted to determine the relative weight of texture and motion cues in the perception of planar-surface slant when both texture and motion convey similar information. Stimuli were monocularly viewed images of planar surfaces slanted in depth, defined by texture and motion information that could be varied independently. Slant discrimination biases and thresholds were measured by a method of single-stimuli binary-choice procedure. When the motion and texture cues depicted surfaces of identical slants, it was found that the depth-from-motion information neither reduced slant discrimination thresholds, nor altered slant discrimination bias, compared to texture cues presented alone. When there was a difference in the slant depicted by motion and by texture, perceived slant was determined almost entirely by the texture cue. The regularity of the texture pattern did not affect this weighting. Results are discussed in terms of models of cue combination and previous results with different types of texture and motion information.
A Code-Theoretical Note on Object Handedness
Authors: Leeuwenberg Emanuel , van der Helm Peter
Published: August 2002

This study is a theoretical exercise dealing with discrimination between images and mirror-images. It focuses on the way codes of shapes represent their handedness. We compare two code systems with different reference frames. These frames determine the specific sensitivity of each system. One system uses an asymmetric reference frame. It is called the H-system and was inspired by an idea of Corballis (1988 Psychological Review95 115–123). The other system, being our proposal, uses a symmetric reference frame and we have named it the M-system. We demonstrate the following. A code of the H-system provides a cue for the handedness of a shape, but not for rotation, ie no cue for the appropriate kind of code rotation which should be tested in case images and mirror-images are discerned by mental rotation. The M-system is the converse in both respects. A code of this system does not provide a handedness cue but, instead, a rotation cue. Thus, for handedness discrimination, the H-system neither needs nor guides mental rotation, whereas the M-system does both. This M-system generates object-centred structural codes enriched with viewpoint information. Various visual experiments reported in the literature favour the M-system over the H-system, implying that perception does not make use of an asymmetric but of a symmetric reference frame.
Performance of Early-Blind and Sighted Children on Olfactory Tasks
Authors: Rosenbluth Ruth , Grossman Ephraim S , Kaitz Marsha
Published: August 2002

The goal of the study was to test whether children with congenital or early-onset blindness outperform sighted children on olfactory tasks. Measures of olfactory sensitivity, odour recognition, and odour labeling were obtained. The results show that the blind children were more proficient at correctly labeling 25 common odours than were matched sighted children. However, the blind were not more sensitive to a target odour, nor more proficient at choosing a correct odour label from a list of four. Together, the data point to a circumscribed advantage of blind children at self-generating and retrieving odour labels and, as such, to a limited, but still compensatory, cognitive function.
Visuospatial Attention: The Role of Target Contrast and Task Difficulty when Assessing the Effects of Cues
Authors: Snowden Robert J , Willey Jennifer , Muir Janice L
Published: August 2002

Cueing paradigms have become popular in assessing the processes of attention. In two experiments we manipulated (i) the contrast of the target, and (ii) the similarity between the targets discriminated. We used a cue that would isolate the exogenous component of attention. Both a reduction in target contrast and an increase in target similarity raised overall reaction times by a similar amount; however, the target contrast manipulation produced a much greater cueing effect compared with the target similarity manipulation. The results suggest that manipulation of target contrast changes the attention cueing effect at a stage of attracting attention to a location of the target (the ‘move’ stage), rather than at a later processing stage.
Velocity Not Acceleration of Self-Motion Mediates Vestibular – Visual Interaction
Authors: Loose Rainer , Probst Thomas
Published: August 2002

We investigated the influence of vestibular stimulation with different angular accelerations and velocities on the perception of visual motion direction. Constant accelerations resulting in different angular velocities and constant angular velocities obtained at different accelerations were combined in twenty healthy subjects. Random-dot kinematograms with coherently moving pixels and randomly moving pixels were used as visual stimuli during whole-body rotations. The smallest percentage of coherently moving pixels leading to a clear perception of motion direction was taken as the perception threshold. Perception thresholds significantly increased with increasing angular velocity. Increased acceleration, however, had no significant effect on the perception thresholds. We conclude that the achieved angular velocity, and not acceleration, is the predominant factor in the processing of vestibular-visual interaction.
Visual Mislocalisation Induced by Translational and Radial Background Motion
Authors: Honda Hitoshi
Published: August 2002

Three experiments were conducted to explore how translational and radial background motion affected visual localisation. In experiment 1, subjects were asked to indicate the apparent position of a small spot of light flashing against a background of vertical stripes, at a varying point in time before and after rapid translational motion of the background to the left or right. When the spot was flashed before the background motion, subjects mislocalised it toward the central fixation point. An interesting finding was that this mislocalisation occurred in most cases when the background moved in the direction opposite to the visual half-field in which the spot was flashed. That is to say, a spot flashed on the right side of the fixation point was mislocalised when its background moved to the left, and not when it moved to the right; and the converse was also true. In experiment 2, concentric circles were used as the background, and moved in a contracting or expanding direction. The results indicated that mislocalisation toward the central fixation point occurred when a spot was flashed before contracting motion of the background. The same mislocalisation was observed for the spot flashed in the lower visual field, but not when it was flashed in the upper visual field (experiment 3). It is concluded that the mislocalisation is a visual illusion induced by a transient background motion toward the central fixation point.
Stereomotion Speed Perception is Contrast Dependent
Authors: Brooks Kevin
Published: August 2002

The effect of contrast on the perception of stimulus speed for stereomotion and monocular lateral motion was investigated for successive matches in random-dot stimuli. The familiar ‘Thompson effect’—that a reduction in contrast leads to a reduction in perceived speed—was found in similar proportions for both binocular images moving in depth, and for monocular images translating laterally. This result is consistent with the idea that the monocular motion system has a significant input to the stereomotion system, and dominates the speed percept for approaching motion.
Spatial Coherence Does Not Affect Contrast Discrimination for Multiple Gabor Stimuli
Authors: Meese Tim S , Hess Robert F , Williams Cristyn B
Published: August 2002

Gestalt grouping rules imply a process or mechanism for grouping together local features of an object into a perceptual whole. Several psychophysical experiments have been interpreted as evidence for constrained interactions between nearby spatial filter elements and this has led to the hypothesis that element linking might be mediated by these interactions. A common tacit assumption is that these interactions result in response modulation which disturbs a local contrast code. We addressed this possibility by performing contrast discrimination experiments using two-dimensional arrays of multiple Gabor patches arranged either (i) vertically, (ii) in circles (coherent conditions), or (iii) randomly (incoherent condition), as well as for a single Gabor patch. In each condition, contrast increments were applied to either the entire test stimulus (experiment 1) or a single patch whose position was cued (experiment 2). In experiment 3, the texture stimuli were reduced to a single contour by displaying only the central vertical strip. Performance was better for the multiple-patch conditions than for the single-patch condition, but whether the multiple-patch stimulus was coherent or not had no systematic effect on the results in any of the experiments. We conclude that constrained local interactions do not interfere with a local contrast code for our suprathreshold stimuli, suggesting that, in general, this is not the way in which element linking is achieved. The possibility that interactions are involved in enhancing the detectability of contour elements at threshold remains unchallenged by our experiments.
The Lady'S Not for Turning: Rotation of the Thatcher Illusion
Authors: Lewis Michael B
Published: August 2002

Inversion is especially detrimental to the processing of faces. This is clearly demonstrated by the Thatcher illusion. It has been suggested that this detriment is due to a loss of holistic or configural processing for inverted faces (Bartlett and Searcy, 1993 Cognitive Psychology25 281–316). Stürzel and Spillmann (2000 Perception29 937–942) suggest that this loss of configural processing occurs suddenly as a face is rotated slowly from upright to inverted. This hypothesis is tested in a study of the reaction times taken to indicate that a face has been Thatcherised at various angles of orientation. The results suggest that there is a gradual loss of configural information rather than a rapid switch from one type of processing to another.