Recovery of High Order Accuracy in Radial Basis Function Approximations of Discontinuous Problems

Radial basis function (RBF) methods have been actively developed in the last decades. RBF methods are global methods which do not require the use of specialized points and that yield high order accuracy if the function is smooth enough. Like other global approximations, the accuracy of RBF approximations of discontinuous problems deteriorates due to the Gibbs phenomenon, even as more points are added. In this paper we show that it is possible to remove the Gibbs phenomenon from RBF approximations of discontinuous functions as well as from RBF solutions of some hyperbolic partial differential equations. Although the theory for the resolution of the Gibbs phenomenon by reprojection in Gegenbauer polynomials relies on the orthogonality of the basis functions, and the RBF basis is not orthogonal, we observe that the Gegenbauer polynomials recover high order convergence from the RBF approximations of discontinuous problems in a variety of numerical examples including the linear and nonlinear hyperbolic partial differential equations. Our numerical examples using multi-quadric RBFs suggest that the Gegenbauer polynomials are Gibbs complementary to the RBF multi-quadric basis.     

Resource Load Prediction of Internet of Vehicles Mobile Cloud Computing

Load-time series data in mobile cloud computing of Internet of Vehicles (IoV) usually have linear and nonlinear composite characteristics. In order to accurately describe the dynamic change trend of such loads, this study designs a load prediction method by using the resource scheduling model for mobile cloud computing of IoV. Firstly, a chaotic analysis algorithm is implemented to process the load-time series, while some learning samples of load prediction are constructed. Secondly, a support vector machine (SVM) is used to establish a load prediction model, and an improved artificial bee colony (IABC) function is designed to enhance the learning ability of the SVM. Finally, a CloudSim simulation platform is created to select the per-minute CPU load history data in the mobile cloud computing system, which is composed of 50 vehicles as the data set; and a comparison experiment is conducted by using a grey model, a back propagation neural network, a radial basis function (RBF) neural network and a RBF kernel function of SVM. As shown in the experimental results, the prediction accuracy of the method proposed in this study is significantly higher than other models, with a significantly reduced real-time prediction error for resource loading in mobile cloud environments. Compared with single-prediction models, the prediction method proposed can build up multidimensional time series in capturing complex load time series, fit and describe the load change trends, approximate the load time variability more precisely, and deliver strong generalization ability to load prediction models for mobile cloud computing resources.     

Effects of glass ionomer cements on bone tissue

In vivo biocompatibility of glass ionomer cements (GICs) was evaluated for use in orthopaedic surgery using a rat model and compared with conventional bone cement, Polymethyl methacrylate, PMMA. The unset GICs and PMMA were inserted into the marrow cavities of rat femora and retained in situ for various periods of time. The PMMA bone cement showed complete biocompatibility with no interference with reparative bone. The conventional GIC with smaller glass particles and lower powder/liquid ratio showed an initial minor toxic effect on rat bone tissue with later disturbance of adjacent bone formation. The conventional GIC with larger-size glass particles and higher powder/liquid ratio and resin-modified GIC showed more severe toxic effect on rat tissue with the resin-modified GIC affecting the rat bone tissue later. The causes of toxicity associated with the conventional GIC with larger glass particles and higher powder/liquid ration and the resin-modified GIC are thought to be related with the unreacted acid component of both materials and longer ongoing metallic ion release.     

Discovery of left-sided superior vena cava during central venous catheterization

PURPOSE: To report a child with the mitochondrial cytopathy of Pearson syndrome and zonular cataract. METHOD: Case report. We describe a 6-year-old boy with Pearson syndrome. RESULTS: At age 3 years, the boy developed secondary strabismus caused by bilateral zonular cataract. Subsequently, he underwent successful bilateral cataract extraction with intraocular lens implantation. Postoperative visual acuity with best correction was RE, 20/25 and LE, 20/40. CONCLUSIONS: Children with Pearson syndrome should be examined ophthalmologically to rule out zonular cataract and possible amblyopia. Mitochondrial cytopathies such as Pearson syndrome should be included in the differential diagnosis of congenital and early juvenile cataract.     

Bias in hard disk drive rotary actuator pivot bearings: measurements and lubrication phenomena

Bias in disk drive rotary actuator bearings exhibits complex behavior related to the history of the actuator movement. This paper investigates the hysteresis component of bias present after seeks. Measurements of bias during full stroke actuator movements composed of multiple seeks of fixed length reveal that the magnitude of the hysteresis decreases as the lengths of component seeks increase up to a critical seek length. When the lengths of the component seek lengths are larger than the critical seek length, the magnitude of the hysteresis remains essentially constant. We explain these phenomena using a hypothesis based on bearing lubrication theory and the relationship between actuator velocity and seek length. We demonstrate a good empirical fit to the data which is strikingly similar from drive to drive and strongly supports our hypothesis.     

Domain swapping in G-protein coupled receptor dimers

Computer simulations were performed on models of the beta2-adrenergic receptor dimer, including 5,6-domain swapped dimers which have been proposed as the active, high affinity form (here the dimer interface lies between helices 5 and 6). The calculations suggest that the domain swapped dimer is a high energy structure in both the apo dimer and in the presence of propranolol. In the presence of agonist the energy of the domain swapped dimer is significantly lowered. Analysis of the dimer structure suggests that the agonist-induced conformational change optimizes the helix-helix interactions at the 5-6 interface. An antagonist on the other hand has little effect on these interactions. These observations are consistent with the hypothesis that the agonist functions by shifting the equilibrium in favour of the domain swapped dimer. Indirect support for the domain swapping hypothesis was obtained from the correlated mutations amongst the external residues of the known beta2-adrenergic receptors. These occur mainly at the 5-6 interface at precisely the locations predicted by the simulations; site-directed mutagenesis data in support of a functional role for these lipid-facing correlated residues is presented. The article includes a review of the experimental evidence for G-protein coupled receptor dimerization. Many other aspects of G-protein coupled receptor activation are discussed in terms of this domain swapping hypothesis     

Comparison of the material properties of PMMA and glass-ionomer based cements for use in orthopaedic surgery

The intrisic benefits of low exotherm and bioactivity have generated interest in utilizing glass-ionomer cements (GIC) as a bone cement replacement in orthopaedic surgery. This paper is concerned with evaluating the mechanical properties of compressive strength, flexural strength, and fracture toughness for two traditional GICs, one resin-modified GIC (an experimental bone cement) and two polymethylmethacrylate (PMMA) cement systems. To determine the suitability of a GIC system for use in the clinical orthopaedic setting, the additional characteristics of setting exotherm and setting time have also been evaluated. The characterization of these two vastly different cement systems has raised some concern as to the applicability of using the current orthopaedic standards for the testing of GIC systems. In particular, issues relating to the strain rate dependence of PMMA cement and the exothermic basis for determining setting time are not applicable as these factors are not characteristic of GIC systems. Whilst the intrinsic benfits of current GIC systems are well understood and generally accepted, this study has shown their intrinsic mechanical properties to be inferior to current PMMA cements. Improvement in the mechanical properties of traditional GICs have been achieved with the addition of a resin component (HEMA). © 2001 Kluwer Academic Publishers     

Toughness of glass fibres reinforced glass-ionomer cements

Two fracture toughness parameters, the critical stress intensity factor, K _c and the work of fracture, W _f have been used to characterise the toughness of conventional and resin-modified glass-ionomer cements reinforced with glass fibres. The critical stress intensity factor was determined from the peak load, and the work of fracture was determined as the energy required to extend an introduced crack through the respective glass ionomers. For both materials, crack propagation became more stable as the weight fraction of glass fibres was increased. Additionally, when the weight percent of glass fibres was increased the work of fracture increased. Fibre bridging at the crack tip resulted in the increase in the work of fracture. As the percentage weight of fibres was increased, the critical stress intensity factor decreased proportionally to the increase in porosity.     

Book reviews

Town Planning in Britain Since 1900: The Rise and Fall of the Planning Ideal. Gordon Cherry (deceased). Oxford, Blackwell, 1996, 260 pp., £13.99, ISBN 0–631–1994–2 (pbk).

Multinationals and European Integration—Trade, Investment and Regional Development. Nicholas A. Phelps. London: Jessica Kingsley, 1997, 181 pp., £18.95, ISBN 1–85302–3531 (pbk).

The New Urban Frontier: Gentrification and the Revanchist City. Neil Smith. London: Routledge, 1996, 262 pp., £45.00, ISBN 0–415–13254–1 (hbk), £14.99, ISBN 0–415–13255‐X (pbk).

GIS and Organizations: How Effective are GIS in Practice? Heather Campbell & Ian Masser. London: Taylor and Francis, 1995, 224 pp., £19.95, ISBN 0–7484–0205–5.

Collaborative Planning: Shaping Places in Fragmented Societies. Patsy Healey. London: Macmillan, 1997, 338 pp., ISBN 0–333–49573‐X (hbk), £12.99, ISBN 0–333–49574–8 (pbk).

Explorations in Planning Theory. S.J. Mandelbaum, L. Mazza & R. Burchell (Eds). New Brunswick, NJ: Center for Urban Policy Research, 1996, 543 pp., $21.95, ISBN 0–88285–154–3.