bluuebunny/crossref_metadata_2025 huggingface dataset:
Using matrix methods to characterise the evolution of deformation induced surface roughness in aluminium sheet
Authors: Stoudt M. R. , Hubbard J. B. , Janet S. A.
Published: April 2008

The deformation induced surface roughness of polycrystalline AA6022-T4 aluminium was evaluated with two different analysis protocols. The first determined the rms roughness Rq with linear roughness profiles to be consistent with literature practice. When plotted against strain, the correlation coefficient indicated an excellent linear fit; however, further analysis revealed the roughening behaviour did not support the literature consensus of a linear relationship between plastic strain and Rq. The second determined Rq by matrix methods. This evaluation demonstrates that when Rq data are acquired via linear profiles, they are strongly influenced by correlations. Conversely, matrix based methods sample all of the data and are unaffected by the presence of correlations. Eliminating the correlations in the profile data produced the same Rq behaviour obtained with the matrix methods. An Rq behaviour that exhibits saturation is more representative of the complexities observed in the plastic deformation process of a polycrystal.
Fracture mechanisms of aluminium cast alloy locally reinforced by SiC particles and Al2O3 whiskers under monotonic and cyclic load
Authors: Rafiquzzaman MD. , Arai Y. , Tsuchida E.
Published: April 2008

In the present paper, fracture mechanisms and corresponding stress distributions in aluminium cast alloy locally reinforced by SiC particles and Al2O3 whiskers under monotonic and cyclic load are investigated experimentally and numerically. The material is monotonically and cyclically deformed to failure at room temperature. The fracture origin and the fracture path are investigated on the fracture surfaces. The fracture occurs in the reinforced part under both monotonic and cyclic loads. Scanning electron microscope (SEM) analysis of fracture surface shows that the fatigue fracture is controlled by the fracture of coarse Al2O3 whiskers. The static fracture (monotonic loading) shows that the fracture mechanism is the combination of reinforcing particle fracture and interfacial debonding between reinforcing ceramics and matrix metal. The stress distributions around the boundary between the reinforced part and the unreinforced part are calculated based on an inclusion array model considering the microscopic inhomogeneous effects. Both the experimental results and the finite element simulation show that the critical location for fracture is changed by the external stress level which controls the local stress distribution through plastic constraint between reinforcing particle and matrix alloy.
Microstructure evolution in hot deformation of 7050 aluminium alloy with coarse elongated grains
Authors: Hu H. E. , Zhen L. , Chen J. Z. , Yang L. , Zhang B. Y.
Published: April 2008

Hot deformation of 7050 aluminium alloy with coarse elongated grains has been investigated by tensile tests conducted at 340 and 460°C and the strain rate of 1˙0 × 10–4–1˙0 × 10–1 s–1. When the 7050 aluminium alloy was conducted at 460°C and 1˙0 × 10–2 s–1, the maximum elongation of 273% is achieved and large plastic deformation was carried out at an almost constant stress. The microstructure evolution under the deformation condition is characterised using OM, SEM, EBSD and TEM in detail. The results show that the microstructure evolution is realised by continuous dynamic recrystallisation in coarse grains. The increase in misorientation is proportional to the increase in the true strain, and the k value, the increasing rate of average misorientation angle, is 15˙7°. The primary hot deformation mechanisms of the 7050 aluminium alloy are localised grain boundary sliding and dislocation gliding, which can increase the grain boundary misorientation continuously.
Effect of heating rate on reaustenitisation of low carbon niobium microalloyed steel
Authors: Martín San D. , Cock de T. , García-Junceda A. , Caballero F. G. , Capdevila C. , de Andrés C. García
Published: April 2008

Austenite formation during a continuous heating in a low carbon niobium microalloyed steel with a pearlite and ferrite initial microstructure has been studied. Characteristic transformation temperatures, Ac1, Acθ and Ac3 and the evolution of austenite formation have been determined by combining dilatometry and metallography in a range of heating rates from 0˙05 to 10 K s–1. It has been observed that nucleation and growth of austenite depends highly on the applied heating rate. At low heating rates (0˙05 K s–1) nucleation of austenite takes place both at pearlite nodules and at ferrite grain boundaries, while for higher heating rates (≥0˙5 K s–1), nucleation at grain boundaries is barely present compared to the nucleation at pearlite nodules. The heating rate also affects the austenite growth path and morphology and, thus, the distribution of martensite in the dual phase microstructure obtained at room temperature.
MW plasma polymer thin film synthesis using diglyme precursor
Authors: Yang J. , Gao J. C.
Published: April 2008

A polyethylene glycol (PEG like) macromolecular structured thin film on Ni/Ti (Nitinol) surface has been synthesised by a microwave plasma enhanced chemical vapour deposition method at room temperatures of 298 K, using diethylene glycol dimethyl ether (CH3O(CH2CH2O)2CH3) as a precursor. A power with microwave frequency 2˙45 GHz was applied for the ignition of the plasma, and Ar was used as the carrier gases. Based on atomic force microscopy studies, the smooth thin films on Nitinol substrates were formed, with highly amorphous polymer structures. X-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectra revealed that the presence of new functional groups on the modified Nitinol surfaces, mainly accumulate the same stoichiometric ratio of C and O with PEG, indicating that PEG like films were principal grown under the experimental condition. In vitro studies showed that platelet rich plasma adsorption on modified Nitinol surface were significantly reduced. The present study proposes that surface modification of PEG like films by plasma polymerisation changed the surface components of Nitinol and subsequently improved the biocompatibility.
Microstructure and properties of AlTiNiMnBx high entropy alloys
Authors: Li C. , Li J. C. , Zhao M. , Zhang L. , Jiang Q.
Published: April 2008

AlTiNiMnB x ( x=0˙1, 0˙2, 0˙4 and 0˙5) high entropy alloys are prepared by an arc furnace. The results show that the alloys have a single bcc crystal structure. Boron additions lead to distortion of the crystal lattice and alloy strengthening. The highest hardness (779 HV) is achieved with 0˙5 at.-%B.
Influence of silicon on cementite precipitation in steels
Authors: Kozeschnik E. , Bhadeshia H. K. D. H.
Published: April 2008

The mechanism by which relatively small concentrations of silicon influence the precipitation of cementite from carbon supersaturated austenite and ferrite are investigated. It is found that one condition for the retardation of cementite is that the latter must grow under para-equilibrium conditions, i.e. the silicon must be trapped in the cementite. However, this is not a sufficient condition in that it can only be effective in retarding the transformation rate if the overall driving force for the reaction is not large. It is demonstrated that the experience that silicon retards the tempering of martensite requires the presence of lattice defects which can reduce the amount of carbon available for precipitation and the associated driving force.
Designing low carbon, low temperature bainite
Authors: Yang H.-S. , Bhadeshia H. K. D. H.
Published: April 2008

The possibility of producing bainite at low temperatures by suppressing transformation using substitutional solutes has been investigated, as an alternative to using large carbon concentrations to achieve the same purpose. It is found that although transformation temperatures can indeed be suppressed in this way, the difference between the bainite and martensite start temperatures diminishes. This, combined with the relatively low carbon concentration of the steels studied, promotes the coarsening of the microstructure via a coalescence of fine bainite plates, which may have detrimental consequences on the properties although this remains to be demonstrated. The study also reveals the need for a better interpretation of the bainite start temperature to cover circumstances where the transformation times are unusually long.
Microstructural characterisation of as cast and homogenised Mg–Gd–Nd–Zr alloys
Authors: Zheng K. Y. , Dong J. , Zeng X. Q. , Ding W. J.
Published: April 2008

Microstructure of as cast and homogenised Mg– xGd–2Nd–0˙5Zr ( x=6, 8, 11, wt-%) alloys has been investigated by using of optical microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry and X-ray diffraction. It was observed that all the as cast alloys contained primary α-Mg solid solution, eutectic structures, cuboid shaped phases, rodlike precipitates and Zr rich clusters. The eutectic phase in Mg–11Gd–2Nd–0˙5Zr was characterised to be of Mg5Gd prototype with stoichiometry near Mg5(Nd xGd1– x, x≈0˙43). Microstructural evolution of the alloys during homogenisation can be divided into three coinstantaneous processes as follows: dissolving of eutectic phases, growth of cuboid shaped phases and coarsening of grains. After appropriate homogenisation, the alloys exhibit microstructure with little eutectic phases, small amount of cuboid shaped phases and relatively fine grains. The cuboid shaped phase with a face centred cubic crystal structure (a≈0˙56 nm) was identified to be a GdH2 type compound.
On the effect of nickel substitution in duplex stainless steel
Authors: Wessman S. M. , Hertzman S. , Pettersson R. , Lagneborg R. , Liljas M.
Published: April 2008

The present experimental and theoretical study investigates the effect of nickel on the phase balance and resulting properties of a 22Cr duplex stainless steel. The decrease in nickel was balanced by nitrogen and manganese additions. It was found that a minimum nickel content was required to maintain mechanical and corrosion properties at technically relevant levels. The influence of increasing nitrogen content on resulting phase composition and properties is discussed.
Efficient estimation of thermophysical parameters for LF6 aluminium alloy
Authors: Zeng Z. , Wang L. J. , Zhang H.
Published: April 2008

The LF6 aluminium alloy is widely used in the aerospace industry, owing to its good corrosion resistance and excellent weld ability. However, its thermophysical parameters, especially in high temperature, have been hardly determined under the general project condition, which have great influence on the accuracy of engineering computation. In the present paper, the optimal annealing temperature of LF6 aluminium alloy was confirmed. Based on the recovery at optimal annealing temperature and the limit annealing temperature respectively, the finite element model was built, and the thermophysical parameters were estimated with the probability design system in ANSYS. The results indicate that, the obtained thermophysical parameters values tally with the project reality. The use of the probability design system has provided one of the phenomenological methods for the solution of the unknown thermophysical parameters, and it is possible to build the corresponding material properties database furthermore.
Robust optimisation of chemical composition of as cast chromium white cast iron using a green sand mould
Authors: Cai A.-H. , Chen H. , An W.-K. , Liu W.-X. , Luo Y. , Li T.-L. , Chen M.
Published: April 2008

An L9 (34) orthogonal experiment was performed for the optimisation of chemical composition of chromium white cast iron. The differences of the models by the orthogonal design and radial base function artificial neural network (RBFANN) were investigated. The results show that Si significantly influences the hardness, and Cu and Cr are main factors influencing the impact toughness. The predicted and simulated results indicate that the RBFANN can not only be used to establish robust model for the orthogonal experiment data but also the RBFANN model is rather better than the quadratic regression. Therefore, the RBFANN method could provide a more accurate model than orthogonal design method for the range of parameters investigated.
Neural network modelling of flow stress in Ti–6Al–4V alloy with equiaxed and Widmanstätten microstructures
Authors: Reddy N. S. , Park C. H. , Lee Y. H. , Lee C. S.
Published: April 2008

In the present study, artificial neural networks (ANNs) were used to model flow stress in Ti–6Al–4V alloy with equiaxed and Widmanstätten microstructures as initial microstructures. Continuous compression tests were performed on a Gleeble 3500 thermomechanical simulator over a wide range of temperatures (700–1100°C) with strain rates of 0˙001–100 s–1 and true strains of 0˙1–0˙6. These tests have been focused on obtaining flow stress data under varying conditions of strain, strain rate, temperature, and initial microstructure to train ANN model. The feed forward neural network consisted of two hidden layers with a sigmoid activation function and backpropagation training algorithm was used. The architecture of the network includes four input parameters: strain rate ϵ, Temperature T, true strain ϵ and initial microstructure and one output parameter: the flow stress. The initial microstructure was considered qualitatively. The ANN model was successfully trained across ( α+ β) to β phase regimes and across different deformation domains for both of the microstructures. Results show that the ANN model can correctly reproduce the flow stress in the sampled data and it can predict well with the nonsampled data. A graphical user interface was designed for easy use of the model.
Effect of boronising on mechanical properties, wear and corrosion of N80 steel
Authors: Tian X. , Lu Y. , Sun S. J. , Wang Z. G. , Hao W. Q. , Zhu X. D. , Yang Y. L.
Published: April 2008

The effect of boronising on N80 steel tube was investigated by pack boriding. During the present investigation, microstructures of boride layer and substrate, hardness, mechanical properties, wear and corrosion were examined. In order to improve the tensile properties of the steel substrate after boronising, four different cooling methods were employed including annealing, air cooling, fan cooling and fan cooling with a graphite bar in the centre of boriding agent. Among these methods, the fan cooling with a graphite bar in the centre of the boriding agent makes the microstructure of ferrite and pearlite finest and the mechanical properties highest, in accordance with the mechanical properties required by API SPEC 5L. The borided N80 steel showed a better wear resistance at an applied load of 50 N with a sliding velocity of 0˙785 m s–1, it also displayed a better corrosion resistance in both H2SO4 and HCl acid environments.
Synthesis and physicochemical response of polyethylene glycol encapsulated nickel ferrite nanoparticles
Authors: Yuan Q. , Rana S. , Srivastava R. S. , Gallo A. , Misra R. D. K.
Published: April 2008

The authors describe here the chemical processing methodology and physicochemical response of superparamagnetic nickel ferrite nanoparticles, which were encapsulated and functionalised with polyethylene glycol to form a core shell structure. The outer shell was subsequently conjugated with tumour recognition moiety, folic acid and loaded with doxorubicin drug to achieve tumour specific drug delivery. Fourier transform infrared spectroscopy confirmed the functionalisation and conjugation steps used in the synthesis of the nanocarrier. The drug release response was characterised by an initial rapid release followed by a controlled release. The study also indicated that it is important to optimise the thickness of the polyethylene glycol shell on the magnetic nickel ferrite core to avoid reduction in the ability of the nanocarrier to experience alternate compressive and tensile stresses caused by the external magnetic field because this leads to reduction in the percentage of drug release.
Numerical identification of material model for C–Mn steel using micro-indentation test
Authors: Kopernik M. , Spychalski M. , Kurzydłowski K. J. , Pietrzyk M.
Published: April 2008

Identification of the elastoplastic material model for C–Mn steel, using finite element model of micro-indentation test developed by the authors and proposed algorithm of inverse analysis, is one of the objectives of the project. The micro-indentation experiment is widely described in the present paper, especially those parts, which are meaningful in getting input data for direct, further application in the numerical model of micro-indentation test and in the inverse procedure. Finite element solution connected with the inverse algorithm, which is based on the simplex method, is used to search for the unknown parameters of material model. Validation of the developed inverse algorithm is the particular objective of the present work. The present paper shows that material model determined using the inverse analysis is in agreement with that obtained from the tensile test. The results coincide also with the data available in the literature.
Core binding factors are necessary for natural killer cell development and cooperate with Notch signaling during T-cell specification
Authors: Guo Yalin , Maillard Ivan , Chakraborti Sankhamala , Rothenberg Ellen V. , Speck Nancy A.
Published: April 2008

CBFβ is the non-DNA binding subunit of the core binding factors (CBFs). Mice with reduced CBFβ levels display profound, early defects in T-cell but not B-cell development. Here we show that CBFβ is also required at very early stages of natural killer (NK)–cell development. We also demonstrate that T-cell development aborts during specification, as the expression of Gata3 and Tcf7, which encode key regulators of T lineage specification, is substantially reduced, as are functional thymic progenitors. Constitutively active Notch or IL-7 signaling cannot restore T-cell expansion or differentiation of CBFβ insufficient cells, nor can overexpression of Runx1 or CBFβ overcome a lack of Notch signaling. Therefore, the ability of the prethymic cell to respond appropriately to Notch is dependent on CBFβ, and both signals converge to activate the T-cell developmental program.
The effect of Korean pine nut oil (PinnoThin™) on food intake, feeding behaviour and appetite: A double-blind placebo-controlled trial
Authors: Hughes Georgina M. , Boyland Emma J. , Williams Nicola J. , Mennen Louise , Scott Corey , Kirkham Tim C. , Harrold Joanne A. , Keizer Hiskias G. , Halford Jason C. G.
Published: April 2008

Certain free fatty acids have been shown to have potent effects on food intake and self-reported changes in appetite; effects associated with increases in the release of endogenous cholecystokinin (CCK) and glucagon like peptide-1 (GLP-1). In the current study, the effects of a Korean pine nut oil product, PinnoThin™, at doses 2 g, 4 g and 6 g triglyceride (TG) and 2 g free fatty acid (FFA), on food intake and appetite were examined in a cross-over double-blind placebo-controlled randomised counter-balanced design in 42 overweight female volunteers. 2 g FFA PinnoThin™, given 30 minutes prior to an ad-libitum buffet test lunch, significantly reduced food intake (gram) by 9% (F(4,164) = 2.637, p = 0.036) compared to olive oil control. No significant effect of PinnoThin™ on macronutrient intake or ratings of appetite were observed. Given the recent data showing that the TG form of PinnoThin™ may also reduce appetite by increasing CCK release, the lack of any effect of the TG form found in this study could be attributed to the timing of the dosing regime. Collectively, these data suggest that PinnoThin™ may exert satiating effects consistent with its known action on CCK and GLP-1 release, and previously observed effects on self-reported appetite ratings.
DNA damage and cytotoxicity in type II lung epithelial (A549) cell cultures after exposure to diesel exhaust and urban street particles
Authors: Danielsen Pernille Høgh , Loft Steffen , Møller Peter
Published: April 2008

Background

Exposure to air pollution particles has been acknowledged to be associated with excess generation of oxidative damage to DNA in experimental model systems and humans. The use of standard reference material (SRM), such as SRM1650 and SRM2975, is advantageous because experiments can be reproduced independently, but exposure to such samples may not mimic the effects observed after exposure to authentic air pollution particles. This study was designed to compare the DNA oxidizing effects of authentic street particles with SRM1650 and SRM2975. The authentic street particles were collected at a traffic intensive road in Copenhagen, Denmark.

Results

All of the particles generated strand breaks and oxidized purines in A549 lung epithelial cells in a dose-dependent manner and there were no overt differences in their potency. The exposures also yielded dose-dependent increase of cytotoxicity (as lactate dehydrogenase release) and reduced colony forming ability with slightly stronger cytotoxicity of SRM1650 than of the other particles. In contrast, only the authentic street particles were able to generate 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in calf thymus DNA, which might be due to the much higher level of transition metals.

Conclusion

Authentic street particles and SRMs differ in their ability to oxidize DNA in a cell-free environment, whereas cell culture experiments indicate that the particle preparations elicit a similar alteration of the level of DNA damage and small differences in cytotoxicity. Although it cannot be ruled out that SRMs and authentic street particles might elicit different effects in animal experimental models, this study indicates that on the cellular level, SRM1650 and SRM2975 are suitable surrogate samples for the study of authentic street particles.
Natural selection of protein structural and functional properties: a single nucleotide polymorphism perspective
Authors: Liu Jinfeng , Zhang Yan , Lei Xingye , Zhang Zemin
Published: April 2008

Background

The rates of molecular evolution for protein-coding genes depend on the stringency of functional or structural constraints. The Ka/Ks ratio has been commonly used as an indicator of selective constraints and is typically calculated from interspecies alignments. Recent accumulation of single nucleotide polymorphism (SNP) data has enabled the derivation of Ka/Ks ratios for polymorphism (SNP A/S ratios).

Results

Using data from the dbSNP database, we conducted the first large-scale survey of SNP A/S ratios for different structural and functional properties. We confirmed that the SNP A/S ratio is largely correlated with Ka/Ks for divergence. We observed stronger selective constraints for proteins that have high mRNA expression levels or broad expression patterns, have no paralogs, arose earlier in evolution, have natively disordered regions, are located in cytoplasm and nucleus, or are related to human diseases. On the residue level, we found higher degrees of variation for residues that are exposed to solvent, are in a loop conformation, natively disordered regions or low complexity regions, or are in the signal peptides of secreted proteins. Our analysis also revealed that histones and protein kinases are among the protein families that are under the strongest selective constraints, whereas olfactory and taste receptors are among the most variable groups.

Conclusion

Our study suggests that the SNP A/S ratio is a robust measure for selective constraints. The correlations between SNP A/S ratios and other variables provide valuable insights into the natural selection of various structural or functional properties, particularly for human-specific genes and constraints within the human lineage.
Drainage and filling in cylindrical and rectangular containers
Authors: Liu T-S , Merati P , Woodiga S A , Davis C , Leong C H , Johnson J , Chen K H
Published: April 2008

Drainage and filling processes in cylindrical and rectangular containers for several motion sequences are experimentally studied using a stereo videogrammetric technique. The measured quantities include the rigid body motion of the containers and the water level relative to the body coordinate system as a function of time. The experimental data are used to validate Torricelli's law and determine the time constant, discharge coefficient, and water volume. In addition, the air funnel shapes in vortical sinks in a stationary cylinder are measured, and the effects of the initial water height and swirling on the drainage are addressed.
A study of combustion, instantaneous heat transfer, and emissions in a spark ignition engine during warm-up
Authors: Wang X , Stone C R
Published: April 2008

A study of the engine combustion, instantaneous heat transfer and exhaust emissions during the warm-up stage has been carried out on a Rover K16 four-cylinder four-valve spark ignition engine. The instantaneous heat transfer has been obtained by an unsteady two-dimensional analysis of the instantaneous surface temperature measurements. The effect of the wall temperature during warm-up on these engine parameters has been investigated under different load and speed conditions. A simplified single-zone heat transfer model has been used to model the engine heat transfer during the warm-up stage. The experimental results show that the increasing wall temperature during warm-up has an impact on the burn duration, in-cylinder heat transfer, and exhaust emissions, such as hydrocarbons and NO x.
Regenerative braking strategy for hybrid electric vehicles based on regenerative torque optimization control
Authors: Wang F , Zhuo B
Published: April 2008

A regenerative torque distribution (RTD) strategy is proposed to make maximum use of the braking energy to improve fuel economy for hybrid electric vehicles, in which the available regenerative braking force, the demand of the front wheel braking force, and the front wheel lock-up force are all explicitly taken into account. The actual front wheel cylinder pressure, which is reduced by the amount of the actual regenerative braking force, is supplied from the electronic hydraulic brake system. An emulated engine compression braking (EECB) is suggested during coasting, and the electric motor provides a negative torque to emulate the internal combustion engine drag torque to charge the ultracapacitor. In addition, a regenerative torque optimization strategy (RTO) is implemented to maximize the actual electric power recuperated by the ultracapacitor. The simulation results show that both the RTD with RTO and the EECB with RTO are able to offer improved ultracapacitor voltages.
A study on the influences of tyre lags and suspension damping on the instantaneous response of a vehicle
Authors: Mavros G
Published: April 2008

The paper aims to quantify the influences of non-steady state tyre behaviour and suspension damping on the instantaneous response of a vehicle to handling manoeuvres. The influences of such parameters cannot be determined using steady state tests. In the present work, a recently developed methodology is employed, which has been applied in the past to simple transient handling studies. Here, the approach is applied to more demanding situations and the effects of tyre lags and suspension damping are directly related to the under-steer, over-steer, or neutral-steer character of the vehicle under test. To distinguish between the effects of tyre force lags, tyre non-linearities, and combined tyre—vehicle non-linearities, an increasingly complex approach is adopted, which involves the implementation of a linear bicycle model, a non-linear bicycle model, and a ten-degrees-of-freedom (10DOF) non-linear vehicle model. In all cases, tyre-force lags are simulated using the relaxation length concept. The 10DOF vehicle model is validated against experimental measurements and forms the basis for fully non-linear studies. It is shown that even inherently under-steering vehicles may initially over-steer as a result of the delayed response of tyres. Finally, it is demonstrated that the proposed approach captures the effect of suspension damping and some problems are discussed regarding its application.
Cooling system improvements — assessing the effects on emissions and fuel economy
Authors: Brace C J , Hawley G , Akehurst S , Piddock M , Pegg I
Published: April 2008

The work reported in this paper details an experimental study of the effects of cooling system hardware changes on diesel engine emissions and fuel economy. Experiments were performed under both steady state and transient conditions and complemented by statistical assessments. Techniques for assessing the thermal integrity of the engine as a consequence of such changes are also presented. An experimental design was constructed to investigate the effect of water pump throttling, coolant flow control through the oil cooler, and the adoption of a pressure resistive thermostat (PRT). Use of these thermal controls offers a useful trade-off between NO x and fuel economy, with a saving of around 3 per cent in b.s.f.c. for a 10 per cent NO x penalty at low load, where NO x output is less of a concern. However, these benefits were not observed during drive cycle testing.
Particle image velocimetry measurements of three proximal anastomosis models under a pulsatile flow condition
Authors: Chua L P , Ji W-F , Yu C M , Zhou T-M , Tan Y S
Published: April 2008

This study was designed to examine the effects of the anastomotic angle on the flow and haemodynamic parameter distribution patterns of the proximal anastomoses, with emphasis on identifying site-specific haemodynamic features that could reasonably be expected to trigger the initiation and further development of anastomotic intimal hyperplasia. Particle image velocimetry measurements were carried out with three simplified glass proximal models under a physiological flow condition. The results revealed that the disturbed flow and the induced shear stress patterns including low recirculation flow, stagnation point, high wall shear stress, high temporal wall shear stress gradient, low time-averaged wall shear stress (TAWSS), and high oscillating shear index (OSI) occurred around the anastomotic joints and the flow field at proximal anastomosis was strongly affected by the anastomotic angle. Among the three models investigated, the 45° backward anastomosis is found to have a smaller low-recirculation-flow region along the graft inner wall, non-stationary stagnation, and separation points, a higher TAWSS and smaller high-OSI low-TAWSS and low-OSI high-TAWSS regions.
Incorporation of large amounts of gentamicin sulphate into acrylic bone cement: Effect on handling and mechanical properties, antibiotic release, and biofilm formation
Authors: Dunne N J , Hill J , McAfee P , Kirkpatrick R , Patrick S , Tunney M
Published: April 2008

Bacterial infection remains a significant complication following total joint replacement. If infection is suspected when revision surgery is being performed, a large dose of antibiotic, usually gentamicin sulphate, is often blended with the acrylic bone cement powder in an attempt to reduce the risk of recurrent infection. In this in-vitro study the effect of small and large doses of gentamicin sulphate on the handling and mechanical properties of the cement, gentamicin release from the cement, and in-vitro biofilm formation by clinical Staphylococcus spp. isolates on the cement was determined. An increase in gentamicin loading of 1, 2, 3, or 4 g, in a cement powder mass of 40 g, resulted in a significant decrease in the compressive and four-point bending strength, but a significant increase in the amount of gentamicin released over a 72 h period. When overt infection was modelled, using Staphylococcus spp. clinical isolates at an inoculum of 1×107 colony-forming units/ml, an increase in the amount of gentamicin (1, 2, 3, or 4 g) added to 40 g of poly(methyl methacrylate) cement resulted in an initial decrease in bacterial colonization but this beneficial effect was no longer apparent by 72 h, with the bacterial strains forming biofilms on the cements despite the release of high levels of gentamicin. The findings suggest that orthopaedic surgeons should carefully consider the clinical consequences of blending large doses (1 g or more per 40 g of poly(methyl methacrylate)) of gentamicin into Palacos® R bone cement for use in revision surgery as the increased gentamicin loading does not prevent bacterial biofilm formation and the effect on the mechanical properties could be important to the longevity of the prosthetic joint.
Competing Norms: Canadian Rural Family Physicians’ Perceptions of Clinical Practice Guidelines and Shared Decisionmaking
Authors: Boivin Antoine , Légaré France , Gagnon Marie-Pierre
Published: April 2008

Objectives

Implementation of clinical practice guidelines (CPGs) and shared decisionmaking are both advocated in primary care. Some authors argue that CPGs can enhance informed decisions by patients and physicians, while others warn that a standardized implementation of CPGs could hinder patients’ involvement in decisionmaking. Our objective was to explore rural family physicians’ perception of the interaction between clinical practice guidelines and shared decisionmaking in medical practice.

Methods

A qualitative study using a semi-structured focus group interview: with 17 family physicians and residents, in a Canadian rural town. Interviews were audio-taped and transcribed verbatim. Thematic content analysis was performed and validated by the constant comparative method, member checking and group debriefing.

Results

Two distinct conceptions of how clinical practice guidelines should assist decisionmaking emerged. On the one hand, guidelines were seen as helping clinicians to make decisions on behalf of their patient about the best course of action. For interventions with uncertain benefit or that carried significant trade-off for patients, guidelines were seen as a tool that should inform decisionmaking between physicians and patients, providing them with details about risks, benefits, costs and alternative treatments. The pressure to apply guideline recommendations was perceived as a potential barrier to patient participation in decisionmaking.

Conclusion

In circumstances where physicians judge patient participation in decisionmaking to be important, physicians perceive a tension between the need to respect patients’ preferences and the pressure to apply guidelines. CPGs should include information that supports shared decisionmaking, besides their current focus on influencing prescription patterns, costs and health outcomes.
Hospital Clinicians’ Attitudes Towards a Statutory Advocacy Service for Patients Lacking Mental Capacity: Implications for Implementation
Authors: Luke Lydia , Redley Marcus , Clare Isabel , Holland Anthony
Published: April 2008

Objectives

To examine attitudes to the Mental Capacity Act's new statutory Independent Mental Capacity Advocate (IMCA) service in England and Wales and consider the implications for its delivery.

Methods

Quantitative data describing all referrals to the seven pilot IMCA services (January 2006-March 2007) and qualitative data from semi-structured interviews with 18 doctors, 21 senior nurses and one discharge planning manager in four general hospitals in England.

Results

Of 127 hospital-based referrals to the seven pilot IMCA services, 29 (23%) were for patients facing serious medical treatments, 52% of whom were judged to lack decisionmaking capacity due to a learning disability; ninety-eight (77%) were for patients facing a change of accommodation upon hospital discharge, 62% of whom were elderly and lacked capacity due to dementia. While aware of the potential benefits of the IMCA service, clinicians were generally negative about the contribution advocates could make to patients’ medical care and thought they could only contribute usefully in a minority of ethically complicated decisions. In contrast, they were more positive about the involvement of advocates in hospital discharge decisions and hoped that they would improve current discharge practice.

Conclusions

Clinicians held ambivalent attitudes towards the involvement of a statutory IMCA service in medical decisions, reflecting beliefs that the service was largely impractical and unnecessary given current procedures for making medical decisions in patients’ ‘best interests’. Conversely, clinicians were more likely to support advocacy in discharge decisions because they believed that non-medically qualified advocates could make a valuable contribution to decisions that were seen as predominantly social and where practice was frequently considered deficient. By holding these beliefs, clinicians are failing to have due regard for the IMCA service as a statutory measure for safeguarding patients’ interests.
Is Fast Access to General Practice all that Should Matter? A Discrete Choice Experiment of Patients’ Preferences
Authors: Gerard Karen , Salisbury Chris , Street Deborah , Pope Catherine , Baxter Helen
Published: April 2008

Objectives

To determine the relative importance of factors that influence patient choice in the booking of general practice appointments for two health problems.

Methods

Two discrete choice experiments incorporated into a survey of general practice patients and qualitative methods to support survey development.

Results

An overall response of 94% (1052/1123) was achieved. Factors influencing the average respondent's choice of appointment, in order of importance, were: seeing a doctor of choice; booking at a convenient time of day; seeing any available doctor; and having an appointment sooner rather than later (acute, low worry condition). This finding was the same for an ongoing, high worry condition but in addition the duration of the appointment was also of (small) value. Patients traded off speed of access for more convenient appointment times (a willingness to wait an extra 2.5-3 days longer to get a convenient time slot for an acute low worry/ongoing, high worry condition, respectively). However, contrary to expectation, patients were willing to trade off speed of access for continuity of care (e.g. willingness to wait five days longer to see the doctor of their choice for an acute, low worry condition). Preferences varied by a person's gender, work and carer status.

Conclusions

Patients hold strong preferences for the way general practice appointment systems are managed. Contrary to current policy on improving access to primary care patients value a more complex mix of factors than fast access at all costs. It is important that policy-makers and practices take note of these preferences.
Legitimacy of Hospital Reconfiguration: The Controversial Downsizing of Kidderminster Hospital
Authors: Oborn Eivor
Published: April 2008

Objectives

This paper examines the contested organizational legitimacy of hospital reconfiguration, which continues to be a central issue in health care management.

Methods

A qualitative study which focuses on the controversial downsizing of Kidderminster Hospital, a highly publicized landmark case of district general hospital closure. Rhetorical strategies are analysed to examine how legitimacy was constructed by stakeholder groups and how these strategies were used to support or resist change.

Results

Stakeholders promoting change legitimized re-organization pragmatically and morally arguing the need for centralization as a rational necessity. Stakeholders resisting change argued for cognitive and moral legitimacy in current service arrangements, contrasting local versus regionalized aspects of safety and provision. Groups managed to talk past each other, failing to establish a dialogue, which led to significant conflict and political upheaval.

Conclusions

Stakeholders value hospitals in different ways and argue for diverse accounts of legitimacy. Broader discourses of medical science and democratic participation were drawn into rhetorical texts concerning regionalization to render them more powerful.
Characteristics of the Emergency and Urgent Care System Important to Patients: A Qualitative Study
Authors: O'cathain Alicia , Coleman Patricia , Nicholl Jon
Published: April 2008

Objectives

To explore patients’ views and experiences of the emergency and urgent care system to inform the development of a questionnaire for routine assessment of the system's performance from the patient perspective.

Methods

Qualitative research with people who had recently used the system: 47 people in eight focus groups and 13 individual interviews.

Results

Recurrent themes included characteristics of the system which are rarely addressed in service-specific questionnaires, in particular, confusion over the most appropriate service to use for particular health problems, coordination between services and informational continuity across services. Other characteristics were identified which, although commonly included in service-specific questionnaires, could have system-level consequences. These included communication between health professionals and patients, and ease of access to services. For example, patients’ perception of poor communication with one service could increase their subsequent use of other services in the system. Proactive behaviour from health professionals was an important system characteristic because it could allay patient anxiety by making patients feel that their concerns were being taken seriously and that staff could sort out problems such as feeling ‘stuck in’ or ‘bounced around’ the system. ‘Candidacy’, whereby eligibility for health care is jointly negotiated between the user and the service provider, was evident as an issue for patients across the social spectrum when seeking help urgently.

Conclusions

Questionnaires designed to assess patients’ views and experiences of emergency and urgent care should address system-level as well as service-specific issues in order to address the full range of patient concerns.
Equity and Service Innovation: The Implementation of a Bibliotherapy Scheme in Wales
Authors: Porter Alison , Peconi Julie , Evans Angela , Snooks Helen , Lloyd Keith , Russell Ian
Published: April 2008

Objective

Book Prescription Wales (BPW) is a pilot bibiliotherapy scheme launched in July 2005 as a primary care treatment option for people with mild to moderate mental health problems. In an innovative model, patients are prescribed self-help books from a list, to borrow from local libraries. Our objective was to evaluate its implementation, focusing on the issue of equity of service delivery.

Methods

Data were gathered from Welsh Assembly Government concerning project set-up and borrowing rates. Mailed questionnaires were completed by 21/22 (95.4%) Local Health Boards and 44/64 (68.8%) Community Mental Health Teams. In addition, 327 out of 497 (66%) primary care practices were surveyed by telephone, 20 prescribers took part in in-depth telephone interviews and three focus groups were conducted with library staff.

Results

From July 2005-March 2006, books were borrowed 15,236 times. There was a 10-fold variation in borrowing rates across local authorities (1.07 to 10.18 loans/1000 people). The priority which Local Health Board staff reported giving to the scheme varied. Uptake among prescribers was mixed: in 35% of general practices (n 5 116) no-one participated. Prescribers reported different ways of using the bibliotherapy scheme. Library staff reported issues of patchy uptake.

Conclusion

Variation in usage of bibliotherapy raises questions about equity; it is unlikely to reflect the distribution of people who could potentially benefit. Factors influencing variation existed all along the implementation chain. It is not always possibly to separate demand-side and supply-side factors when considering equity and service innovation in health care.
Part of a Global Workforce: Migration of British-Trained Pharmacists
Authors: Hassell Karen , Nichols Liza , Noyce Peter
Published: April 2008

Objectives

Many countries, including the UK, have identified a shortage of pharmacists, partly due to emigration. This study was undertaken to examine the extent and nature of migration taking place among British-qualified pharmacists.

Methods

Mixed methods, including secondary analysis of quantitative data, qualitative research and a large self-completion survey of all British-registered pharmacists with an overseas address.

Results

Almost 11% of British-registered pharmacists reside overseas. Nearly three-quarters are British-trained and most are UK nationals. The US, Canada and Australia are the main destinations. The majority work as pharmacists in health services, but sizeable proportions are either retired, not working for other reasons or work in industry. Those who emigrate include those returning home, moving for career opportunities, for lifestyle reasons or as a ‘spouse trailer’. For many the move abroad is a permanent one.

Conclusions

Great Britain is both a source and destination country for migrating pharmacists. Emigration currently exceeds immigration. Pharmacists are not migrating to developing countries, so the profession may want to consider ways of contributing to the health care systems in developing countries which are the source of some of the immigrant pharmacists to Great Britain.
The Increasing Burden of Alcoholic Liver Disease on United Kingdom Critical Care Units: Secondary Analysis of a High Quality Clinical Database
Authors: Welch Catherine , Harrison David , Short Alasdair , Rowan Kathryn
Published: April 2008

Objectives

To investigate the effect of increasing alcohol consumption on the number of admissions to adult, general critical/intensive care units (ICUs) in England and Wales with alcoholic liver disease, their case mix, mortality, and impact on critical care and hospital activity by extrapolating from admissions to ICUs over the last 10 years.

Methods

Secondary analysis of a high quality clinical database from a national clinical audit using data from 385,429 admissions to174 ICUs in England and Wales between December 1995 and July 2005, of which 4219 (1.1%) had alcoholic liver disease. The extrapolated total number of admissions with alcoholic liver disease and total number of ICU bed-days occupied were calculated. Changes over time in the case mix (age, sex and APACHE II and ICNARC risk prediction models), mortality at ultimate discharge from acute hospital, and length of stay in ICU and in hospital were explored.

Results

The percentage of ICU admissions with alcoholic liver disease increased from 0.65% in 1996 to 1.35% in 2005, but the case mix remained similar. Mortality decreased and length of stay increased over this period. The extrapolated total number of admissions to all 229 adult, general critical care units in England and Wales increased from 550 in 1996 to 1513 in 2005, and the extrapolated total number of bed-days occupied by these admissions increased from around 3100 to over 10,000.

Conclusions

Admissions to ICUs in England and Wales with alcoholic liver disease tripled over the 10-year period from 1996 to 2005. The continuing increase in alcohol consumption means that this trend is likely to continue.