bluuebunny/crossref_metadata_2025 huggingface dataset:
Moderate intensity static magnetic field has bactericidal effect on E. coli and S. epidermidis on sintered hydroxyapatite
Authors: Bajpai Indu , Saha Naresh , Basu Bikramjit
Published: May 2012

The application of electromagnetic field in the context of bacteria associated infections on biomaterial surfaces has not been extensively explored. In this work, we applied a moderate intensity static magnetic field (100 mT) to understand the adhesion and growth behavior of both gram positive (S. epidermidis) and gram negative bacteria (E.
coli) and also to investigate bactericidal/bacteriostatic property of the applied electromagnetic field. An in‐house built magnetometer was used to apply static homogeneous magnetic field during a planned set of in vitro experiments. Both the sintered hydroxyapatite (HA) and the control samples seeded with bacteria were exposed to the magnetic field (100 mT) for different timescale during their log phase growth. Quantitative analysis of the SEM images confirms the effect of electromagnetic field on suppressing bacterial growth. Furthermore, cell integrity and inner membrane permeabilization assays were performed to understand the origin of such effect. The results of these assays were statistically analyzed to reveal the bactericidal effect of magnetic field, indicating cell membrane damage. Under the investigated culture conditions, the bactericidal effect was found to be less effective for S. Epidermidis than E.
coli. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2012:100B:1206–1217, 2012.
Experimental repair of segmental bone defects in rabbits by angiopoietin‐1 gene transfected MSCs seeded on porous β‐TCP scaffolds
Authors: Cao Le , Liu Xudong , Liu Shen , Jiang Yao , Zhang Xianlong , Zhang Changqing , Zeng Bingfang
Published: May 2012

Segmental bone defect repair remains a clinical and experimental challenge in tissue engineering with increasing focus on angiogenesis in the bone substitutes. The objective of this study was to investigate the osteogenic effects of angiopoietin‐1 (Ang‐1) gene transfected bone marrow‐derived mesenchymal stem cells (MSCs) seeded on porous β‐TCP scaffolds. This bone substitute (experimental group) and MSCs/β‐TCP compounds (control group) were implanted into 15 mm segmental bone defects of the radii of 30 New Zealand white rabbits, with platelet‐rich plasma injected at the same time. Bone regeneration and angiogenesis were assessed by Scanning electron microscope (SEM), X‐ray, histology, immunohistology, and biomechanical outcome measurements made on the 2nd, 4th, 8th, and 12th week after the operation. In vitro, the amount of proliferation and differentiation of Ang‐1 gene transfected MSCs was found to be gross increased than that of the control groups. In vivo, a significantly increased amount of new bone formation accompanied by active capillary vasculature regeneration was observed in the pores of the scaffolds which had been seeded with Ang‐1 gene transfected MSCs, as compared with the control groups. The biomechanical test confirmed the failure load of new born bone was close to normal bone. These results suggest that transfer of gene encoding Ang‐1 to MSCs increases their osteogenic properties by enhancing capillary regeneration, thus providing a rich blood supply for new bone formation in segmental bone defects. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Physicochemical properties and in vitro biocompatibility of a hydraulic calcium silicate/tricalcium aluminate cement for endodontic use
Authors: Liu Weining , Peng Weiwei , Zhu Yaqin , Chang Jiang
Published: May 2012

This study sought to prepare a calcium silicate cement (CSC) with varying additions of tricalcium aluminate (Ca3Al2O6, C3A), and to find an optimal amount of C3A by evaluating the effect of C3A on the physicochemical and in vitro biological properties of the CS/C3A cement. The results indicated that the addition of C3A into CSC reduced the setting time and improved the compressive strength especially at the early stage of setting. However, the 15% C3A was too much for the CS/C3A system and did harm to its strength development. Furthermore, the CS/C3A cement was bioactive and biocompatible in vitro, and had a stimulatory effect on the cell growth, when the content of C3A was 5 or 10%. When compared with the commercially available Dycal®, the CS/C3A cement was notably more compatible with the human dental pulp cells. Therefore, the CS/C3A cement with 5–10% C3A produced the best compromise between setting and in vitro biological properties, and may be a promising candidate for endodontic use. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
A generalized reference state extends the applicability of approximative kinetics in metabolic engineering
Authors: Nikerel Emrah , Verheijen Peter J. T. , Heijnen Joseph J.
Published: May 2012

BACKGROUND: The use of approximative kinetics for modeling enzyme kinetics and for metabolic engineering purposes has become increasingly attractive. Despite a list of advantages, the proposed use of a steady state for reference limits the use of such kinetic formats.

RESULTS: Here, to avoid these limitations, an alternative formulation is proposed for the linlog approximative kinetics introducing ‘a characteristic set’ for normalization. The necessary equations for the parameter (elasticities and the reaction rate of the characteristic set) estimation framework using data obtained from various types of perturbation experiments are given. The use of the new formulation is exemplified with three illustrative examples: parameter estimation in steady state and in dynamic experiments; and prediction of the effect of a mutation in enzyme kinetics properties. The implications of the new formulation are discussed.

CONCLUSIONS: By introducing a so‐called characteristic set, we show that the approximative quality of this kinetics is improved and this formulation can be used to analyze and model data from a broader set of experimental scenarios. Copyright © 2012 Society of Chemical Industry
Promiscuous enzyme‐catalyzed Michael addition: synthesis of warfarin and derivatives
Authors: Xie Bang‐Hua , Guan Zhi , He Yan‐Hong
Published: May 2012

BACKGROUND: Biocatalytic promiscuity has attracted much attention from chemists and biochemists in recent years. Warfarin, one of the most effective anticoagulants, has been introduced for clinical use as a racemate for more than half a century. Although some different chemical strategies towards the synthesis of optically active warfarin have been reported, biocatalytic preparation of warfarin remains unexploited.

RESULTS: Lipase from porcine pancreas (PPL) was used as a biocatalyst to catalyze the Michael addition of 4‐hydroxycoumarin to α,β‐unsaturated enones in organic medium in the presence of water to synthesize warfarin and derivatives. The products were obtained in moderate to high yields (up to 95%) with none or low enantioselectivities (up to 28% ee). The influence of reaction conditions including solvents, temperature and molar ratio of substrates was systematically investigated.

CONCLUSION: Among the many reported lipase‐catalyzed Michael additions, only a few showed enantioselectivity. Therefore, this Michael addition activity of, for example, PPL is a valuable case of enantioselective lipase catalytic promiscuity. In addition, it was the first time warfarin and derivatives were prepared using a biocatalyst. Copyright © 2012 Society of Chemical Industry
Transition metal mediated synthesis using [11C]CO at low pressure – a simplified method for 11C‐carbonylation
Authors: Eriksson Jonas , van den Hoek Johan , Windhorst Albert D.
Published: May 2012

Transition metal mediated carbonylation with [11C]CO has proven a useful method to label a wide array of compounds in the carbonyl position. However, the general use in radiopharmaceutical synthesis has been hampered by the low solubility of carbon monoxide in most solvents and the resulting challenge to confine [11C]CO in low volume reaction vessels. This paper introduces a method that utilises xenon to transfer pre‐concentrated [11C]CO to a sealed disposable glass vial containing carbonylation reagents. The high solubility of xenon in the organic solvent made it possible to confine the [11C]CO without utilising a pressure autoclave or chemical trapping additives. The utility of the method in 11C‐carbonylation was investigated by conducting three model reactions, where [11C‐carbonyl]N‐benzylbenzamide, [11C‐carbonyl]triclocarban and [11C‐carbonyl]methyl nicotinate were afforded in decay corrected radiochemical yields of 71 ± 6%, 42 ± 15% and 29 ± 10%, respectively. These promising results and the straight forward technical implementation suggest that 11C‐cabonylation can become a viable mean to provide labelled carbonyl functionalities in routine radiopharmaceutical synthesis. Compounds labelled with short lived positron emitters are used in Positron Emission Tomography, a molecular imaging technology with applications in clinical diagnostics, clinical research and basic biomedical research.
Subject movement during multislice interleaved MR acquisitions: Prevalence and potential effect on MRI‐derived brain pathology measurements and multicenter clinical trials of therapeutics for multiple sclerosis
Authors: Gedamu Elias L. , Gedamu Abraham
Published: May 2012

Purpose:

To show the prevalence of inter‐packet motion in clinical trial magnetic resonance imaging (MRI) data and the effect of inter‐packet motion on MRI‐derived brain pathology measurements.

Materials and Methods:

We present a method to detect and quantify inter‐packet motion, apply it to 2384 MRIs to determine the prevalence of inter‐packet motion in clinical trial data, and show the effect of inter‐packet motion on measuring multiple sclerosis (MS) lesion volumes.

Results:

Experiments with simulated data showed that the detection procedure was accurate at measuring the amount of movement between packets and quantifying the amount of missing data. Application to clinical trial data demonstrated that a large number of MRIs had missing data due to inter‐packet motion; 20% of the images had greater than 10% of the data missing and 10% of the images had greater than 15% of the data missing. These levels corresponded to thresholds where lesions were difficult to visually identify or disappeared completely. Lesion volume measurement errors ranged from 1.3 ± 0.5% to 9.9 ± 6.3%.

Conclusion:

Inter‐packet motion can introduce substantial errors to MRI‐derived brain pathology measurements. The prevalence of inter‐packet motion is substantial in MS clinical trial data. Automated detection procedures should be implemented to increase the fidelity of MRI‐derived measurements. J. Magn. Reson. Imaging 2012;36:332–343. © 2012 Wiley Periodicals, Inc.
The twisted tale of saturated fat
Authors: Volek Jeff S. , Volk Brittanie M. , Phinney Stephen D.
Published: May 2012

Recent research results mandate a careful re‐evaluation of the widespread belief that dietary saturated fat is harmful. Specifically, multiple recent reports find no association between dietary saturated fat intakes and cardiovascular disease (CVD). There is, however, a consistent pattern of increased risk for both CVD and type‐2 diabetes associated with increased levels of saturated fatty acids (SFA) in circulating lipids. This raises the important question as to what contributes to increased levels of saturated fat in the blood? Whereas dietary intake of saturated fats and serum levels of SFA show virtually no correlation, an increased intake of carbohydrate is associated with higher levels of circulating SFA. This leads to the paradoxical conclusion that dietary saturated fat is not the problem; rather it's the over‐consumption of carbohydrate relative to the individual's ability to metabolize glucose without resorting to de novo lipogenesis. From this perspective, insulin resistant states like metabolic syndrome and type‐2 diabetes can be viewed as carbohydrate intolerance, in which a high carbohydrate intake translates to increased serum SFA and therefore increased risk.
Production and properties of chlorogenic acid lipophilic esters
Authors: Pencreac'h Gaëlle , Lorentz Cécile , Ergan Françoise , Soultani‐Vigneron Samia
Published: May 2012

Chlorogenic acid is a dietary polyphenol with important bioactivities. However, its high hydrophilicity prevents its applications as an antioxidant for lipid protection in a complex matrix such as food. Grafting an aliphatic chain onto chlorogenic acid, so‐called lipophilisation, via lipase‐catalysed esterification represents an efficient means of increasing its lipophilicity. A series of alkyl esters with various chain lengths were produced and used to explore the structure‐antioxidant activity relationship of amphiphilic antioxidants. Data obtained from complex systems (oil‐in‐water emulsion and cell culture) concluded that short or medium chain lengths enhance the antioxidant activity while longer chains tend to decrease the antioxidant ability of chlorogenic acid. This phenomenon remains to be fully explained. Acyl esters, in which the carboxylic acid group remains free were also produced and were shown to be interesting antioxidant candidates as well as useful tools for the understanding of antioxidant activities.
Optimum shape design for surface of a thermohydrodynamic lubrication slider bearing
Authors: Alyaqout Sulaiman F. , Elsharkawy Abdallah A.
Published: May 2012

This paper utilises a thermohydrodynamic model of bearing to optimise the shape of slider bearing. Friction is minimised subject to load and centre of pressure requirements using a sequential quadratic programming algorithm. A generalised Reynolds equation is solved simultaneously with an energy equation using the finite volume method to obtain bearing characteristics, such as friction, load and centre of pressure. Results show that the coefficient of friction is reduced by the optimisation approach. Results also show that larger temperature–viscosity coefficient and inlet viscosity tend to yield smaller optimal friction, whereas larger thermal conductivity tends to yield larger optimal friction. Copyright © 2012 John Wiley & Sons, Ltd.
Materials and Corrosion 5/2012
Authors: Li Q. , Turhan M. C. , Rottmair C. A. , Singer R. F. , Virtanen S.
Published: May 2012

Cover: The main image was taken by optical microscopy and shows a polished 0.1 wt% well‐dispersed MWCNT/AZ91 sample after 1 day immersion in 3.5% NaCl. The inset presents a SEM image of pristine MWCNTs, which we postulate to act as electrodes in the AZ91 composites. The evenly distributed corrosion pattern in the main image indicates that with well‐dispersed MWCNTs in AZ91, formation of galvanic couples takes place everywhere on the composite surface. The corrosion rate of the AZ91 composites with well dispersed MWCNTs is therefore strongly increased compared to the composites with less well dispersed MWCNTs and pure AZ91.

More detailed information can be found in: Q. Li, M. C. Turhan, C. A. Rottmair, R. F. Singer, S. Virtanen, Influence of MWCNT Dispersion on Corrosion Behaviour of their Mg Composites, Materials and Corrosion 2012, 63, 384.
Ceramic Filament Fibers – A Review
Authors: Schawaller Dirk , Clauß Bernd , Buchmeiser Michael R.
Published: May 2012

Ceramic fibers are essential components of new high‐temperature‐resistant lightweight materials. The production routes of ceramic filament fibers are complex and in most cases polymeric components or structures are key factors for fiber spinning. Either organic polymers are used as additives in the spinning dopes for oxide ceramic fibers or inorganic polymers are the precursors for the production of non‐oxide fibers. This paper gives an up‐to‐date overview about different ceramic fibers and the chemistry behind the fiber development and production.

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Länger, stabil: Neues von Acenen
Authors: Wegner Hermann A.
Published: May 2012

Acene sind viel versprechende Grundstrukturen für die molekulare Elektronik. Substituenten und eingeführte Heteroatome verändern die Eigenschaften und die Stabilität von Acenen teils dramatisch.
Proteine auf medizinischen und technischen Substraten
Authors: Ziegler Christiane , Müller Christine
Published: May 2012

Bevor sich auf einer festen Oberfläche ein Biofilm bildet, adsorbieren in der Regel Proteine. Ein solches Adsorbat zu charakterisieren, erfordert die Kombination mehrerer oberflächenanalytischer Methoden, die alle ihre spezifischen Grenzen haben. Oft gelingt es nur in kleinen Schritten und über Modellsysteme, ein Proteinadsorbat auf einer realen Oberfläche zu beschreiben.
Flüchtige Substanzen in Wasser
Authors: Meletis Panos
Published: May 2012

Die deutsche Trinkwasserverordnung fordert, gesundheitsschädliche flüchtige organische Substanzen wie Benzol oder Vinylchlorid zu überwachen. Um Spuren der Substanzen mit Headspace‐GC‐MS zu identifizieren und zu quantifizieren, hilft eine Kühlfalle am Säulenanfang direkt unter dem Injektor. Sie fokussiert den Analyten, so dass die Peaks schärfer werden und die Empfindlichkeit des Messverfahrens steigt.
Steepest descent preconditioning for nonlinear GMRES optimization
Authors: Sterck Hans De
Published: May 2012

Steepest descent preconditioning is considered for the recently proposed nonlinear generalized minimal residual (N‐GMRES) optimization algorithm for unconstrained nonlinear optimization. Two steepest descent preconditioning variants are proposed. The first employs a line search, whereas the second employs a predefined small step. A simple global convergence proof is provided for the N‐GMRES optimization algorithm with the first steepest descent preconditioner (with line search), under mild standard conditions on the objective function and the line search processes. Steepest descent preconditioning for N‐GMRES optimization is also motivated by relating it to standard non‐preconditioned GMRES for linear systems in the case of a standard quadratic optimization problem with symmetric positive definite operator. Numerical tests on a variety of model problems show that the N‐GMRES optimization algorithm is able to very significantly accelerate convergence of stand‐alone steepest descent optimization. Moreover, performance of steepest‐descent preconditioned N‐GMRES is shown to be competitive with standard nonlinear conjugate gradient and limited‐memory Broyden–Fletcher–Goldfarb–Shanno methods for the model problems considered. These results serve to theoretically and numerically establish steepest‐descent preconditioned N‐GMRES as a general optimization method for unconstrained nonlinear optimization, with performance that appears promising compared with established techniques. In addition, it is argued that the real potential of the N‐GMRES optimization framework lies in the fact that it can make use of problem‐dependent nonlinear preconditioners that are more powerful than steepest descent (or, equivalently, N‐GMRES can be used as a simple wrapper around any other iterative optimization process to seek acceleration of that process), and this potential is illustrated with a further application example. Copyright © 2012 John Wiley & Sons, Ltd.
Efficient non‐linear proper orthogonal decomposition/Galerkin reduced order models with stable penalty enforcement of boundary conditions
Authors: Kalashnikova I. , Barone M. F.
Published: May 2012

An efficient, stability‐preserving model reduction technique for non‐linear initial boundary value problems whose solutions exhibit inherently non‐linear dynamics such as metastability and periodic regimes (limit cycles) is developed. The approach is based on the ‘continuous’ Galerkin projection approach in which the continuous governing equations are projected onto the reduced basis modes in a continuous inner product. The reduced order model (ROM) basis is constructed via a proper orthogonal decomposition (POD). In general, POD basis modes will not satisfy the boundary conditions of the problem. A weak implementation of the boundary conditions in the ROM based on the penalty method is developed. Asymptotic stability of the ROM with penalty‐enforced boundary conditions is examined using the energy method, following linearization and localization of the governing equations in the vicinity of a stable steady solution. This analysis, enabled by the fact that a continuous representation of the reduced basis is employed, leads to a model reduction method with an a priori stability guarantee. The approach is applied to two non‐linear problems: the Allen–Cahn (or ‘bistable’) equation and a convection‐diffusion‐reaction system representing a tubular reactor. For each of these problems, bounds on the penalty parameters that ensure asymptotic stability of the ROM solutions are derived. The non‐linear terms in the equations are handled efficiently using the ‘best points’ interpolation method proposed recently by Peraire, Nguyen et al. Numerical experiments reveal that the POD/Galerkin ROMs with stability‐preserving penalty boundary treatment for the two problems considered, both without as well as with interpolation, remain stable in a way that is consistent with the solutions to the governing continuous equations and capture the correct non‐linear dynamics exhibited by the exact solutions to these problems. Published 2012. This article is a US Government work and is in the public domain in the USA.
Biquadratic finite volume element method based on optimal stress points for second order hyperbolic equations
Authors: Yu Changhua , Li Yonghai
Published: May 2012

Based on optimal stress points, we develop a full discrete finite volume element scheme for second order hyperbolic equations using the biquadratic elements. The optimal order error estimates in L∞(H1), L∞(L2) norms are derived, in addition, the superconvergence of numerical gradients at optimal stress points is also discussed. Numerical results confirm the theoretical order of convergence. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2013
Life‐sustaining treatment decisions in the ICU for patients with ESLD: A prospective investigation
Authors: Hansen Lissi , Press Nancy , Rosenkranz Susan J. , Baggs Judith Gedney , Kendall Judith , Kerber Amanda , Williamson Angel , Chesnutt Mark S.
Published: May 2012

We conducted a prospective study in the ICU of life‐sustaining treatment and comfort care decisions over time in patients with end‐stage liver disease (ESLD) from the perspectives of patients, family members, and healthcare professionals. Six patients with ESLD, 19 family members, and 122 professionals participated. The overarching theme describing the decision‐making process was “on the train.” Four sub‐themes positioned patients and family members as passengers with limited control, unable to fully understand the decision‐making process. Findings suggest that including patients and family members in non‐immediate life‐saving decisions and verifying early on their understanding may help to improve the decision‐making process. © 2012 Wiley Periodicals, Inc. Res Nurs Health 35:518–532, 2012
Comparative characterization of oligomeric precursors intended for injectable implants
Authors: López Alejandro , Persson Cecilia , Hilborn Jöns , Rojas Ramiro
Published: May 2012

The use of injectable materials is a simple approach for drug delivery and tissue repair, in, e.g. minimally invasive surgery applications. If these materials are used past their glass transition temperature and have a low viscosity, they will be able to flow while delivered in situ. Whether these materials are to be used as low viscosity drug carriers or further crosslinked for tissue repair, there is a need for a better understanding of their handling properties. In this study, oligo(trimethylene carbonate) (oTMC) and oligo[D,L‐lactide‐co‐(ε‐caprolactone)] (oDLLA‐co‐CL) of various molecular weights within a relevant injectability range were synthesized via ring‐opening polymerization. The materials were comparatively characterized by 1H NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and rheological measurements. After comparing the viscosities and molecular weights of the materials, it was concluded that oDLLA‐co‐CLs were, generally, better suited as an injectable in situ crosslinking network, whereas oTMCs were found to be better candidates as injectable drug carriers. This study provides useful data and guidelines on the use of these and other similar oligomers intended for injectable implants. Copyright © 2012 John Wiley & Sons, Ltd.
Personality disorders with over‐regulation of emotions and poor self‐reflectivity—The case of a man with avoidant and not‐otherwise specified personality disorder and social phobia treated with Metacognitive Interpersonal Therapy
Authors: Dimaggio Giancarlo , Attinà Giovanna , Popolo Raffaele , Salvatore Giampaolo
Published: May 2012

Treating patients with personality disorders (PD) with significant over‐regulation of affects, poor metacognition and a restricted interpersonal schema repertoire requires specialized procedures. We present here the case of a man in his 30s suffering from Avoidant PD and overall 21 PD criteria met, with co‐occurring axis I disorders. Metacognitive Interpersonal Therapy was used, and after 1 year of therapy, outcome was good, although therapy is still continuing. First, a more nuanced understanding of mental states and then attempts at change began, which led to a modification of the patient's negative self‐image and a reduction of social avoidance. The possible relevance and generalization of formalized procedures, applied with a careful case formulation, is discussed to successfully treat persons with this type of complex PD. Copyright © 2012 John Wiley & Sons, Ltd.
Mass spectrometry‐based targeted quantitative proteomics: Achieving sensitive and reproducible detection of proteins
Authors: Boja Emily S. , Rodriguez Henry
Published: May 2012

Traditional shotgun proteomics used to detect a mixture of hundreds to thousands of proteins through mass spectrometric analysis, has been the standard approach in research to profile protein content in a biological sample which could lead to the discovery of new (and all) protein candidates with diagnostic, prognostic, and therapeutic values. In practice, this approach requires significant resources and time, and does not necessarily represent the goal of the researcher who would rather study a subset of such discovered proteins (including their variations or posttranslational modifications) under different biological conditions. In this context, targeted proteomics is playing an increasingly important role in the accurate measurement of protein targets in biological samples in the hope of elucidating the molecular mechanism of cellular function via the understanding of intricate protein networks and pathways. One such (targeted) approach, selected reaction monitoring (or multiple reaction monitoring) mass spectrometry (MRM‐MS), offers the capability of measuring multiple proteins with higher sensitivity and throughput than shotgun proteomics. Developing and validating MRM‐MS‐based assays, however, is an extensive and iterative process, requiring a coordinated and collaborative effort by the scientific community through the sharing of publicly accessible data and datasets, bioinformatic tools, standard operating procedures, and well characterized reagents.
Sigpep: Calculating unique peptide signature transition sets in a complete proteome background
Authors: Helsens Kenny , Mueller Michael , Hulstaert Niels , Martens Lennart
Published: May 2012

We have created a new software platform called sigpep that analyzes transition redundancy in selected reaction monitoring assays. Building on this platform, we also created a web application to generate transition sets with unique signatures for targeted peptides. The platform has been made available under the permissive Apache 2.0 open‐source license, and the web application can be accessed from http://iomics.ugent.be/sigpep.
Physiotherapy after stroke: More is better?
Authors: Langhorne Peter , Wagenaar Robert , Partridge Cecily
Published: May 2012

Physiotherapy is an established component of stroke rehabilitation but uncertainties remain about the most appropriate intensity of therapy input. We conducted a systematic review of the randomised trials of physiotherapy after stroke where qualitatively similar therapy regimens were provided at different levels of intensity. A heterogeneous group of seven randomised trials (597 patients) was identified. Dichotomous outcomes (death or the combined poor outcome of death or deterioration) were analysed by use of the odds ratio and 95% confidence interval. Patients subjected to more intensive physiotherapy input showed a non‐significant reduction in case fatality (odds ratio 0.60; 95% CI 033–1.09) and a significant reduction (OR 0.54; 95% CI 0.34–0.85; p<0.01) in the combined poor outcome of death or deterioration by the end of follow‐up. Two statistical techniques were used to identify patterns within the continuous data. Firstly, impairment and disability scores were converted to a standardised measure of 0–100 and the weighted mean difference (WMD) between the scores in the intensive and conventional physiotherapy groups were then calculated. Modest improvements were observed in both the impairment (WMD+5; 95% CI–1–11) and disability scores (WMD+5; 95% CI 0–10) recorded at the initial review (median 3 months post‐stroke), but not at the final review (median 1 year post‐stroke). Secondly, Fisher's inverse chi‐squared test was used to combine the p values from individual trials; this confirmed the above findings (p<0.05 at initial review; p>0.05 at final review). More intensive physiotherapy input was associated with a reduction in the combined poor outcome of death or deterioration and may enhance the rate of recovery. These observations warrant further investigation.
Physiotherapy in knee osteoarthrosis: Effect on pain and walking
Authors: Börjesson M , Robertson E , Weidenhielm L , Mattsson E , Olsson E
Published: May 2012

Patients with knee osteoarthrosis are often referred for physiotherapy and many different types of treatment are given. The value of many of these treatments has been questioned. This study was intended to evaluate the effect of commonly used physiotherapy treatments in a training programme on patients with medial knee osteoarthrosis, scheduled for surgery. The results from this study also provide useful data for further evaluation of different physiotherapy treatments to this patient group. Thirty‐four patients were randomised to physiotherapy three times a week for 5 weeks and the other 34 received no treatment. The training programme is described in detail. The patients were evaluated by clinical examination, step test, gait analysis and isokinetic measurements of thigh muscle strength before and after treatment. The patients in the treatment group experienced a feeling of overall improvement in the knee and the ability to descend steps improved when compared to the control group. There were no significant differences in gait, range of motion or isokinetic measurements of muscle strength between the groups. We conclude that physiotherapy as given here made our patients feel better and their ability to descend stairs improved. These improvements are beneficial to the patients and support the positive effects of exercises and activity. Whilst the objective improvements were small, suggesting that this treatment may not be justified, patients in the treatment group believed that they were improved.
The reliability of measuring quadriceps cross‐sectional area with compound B ultrasound scanning
Authors: Howe Tracey E , Oldham Jackie A
Published: May 2012

Many therapists use thigh circumference as a measure of quadriceps size to evaluate the effect of an injury or effectiveness of an intervention. However, this technique has been shown to be unreliable, thus more accurate methods of measuring muscle size are required. The purpose of this study was to investigate the validity and reliability of measuring quadriceps cross‐sectional area (CSA) with static compound B ultrasound scanning at the level of the mid‐thigh. Repeated measures of known linear distances and CSAs were made with a planimetry device. Both face and criterion validity were demonstrated indicating that the device is reliable when measuring CSAs. A single rater located quadriceps muscle borders and measured CSAs on a series of ultrasound scans. A mean coefficient of variation (%CV = 1.7) was observed, signifying high intra‐rater reliability. Two raters performed six scans on each of 15 subjects. Initial observation of these results suggest that the measurement of quadriceps CSA with compound B ultrasound scanning is reliable, mean %CVs = 2.8 and 1.9 for the two raters and 2.4 when their results were combined. When raters performed scans on 18 subjects on two occasions on the same day intra‐class correlation coefficients (ICC) were high, 0.991 and 0.980 for raters A and B, respectively. Paired Student's t‐tests revealed a significant difference (p<0.05) for Rater B between CSAs measured for initial and relocated scans. However, this difference was calculated as 1.4–2.9% and was not of clinical importance. A significant difference (p<.0.05) was observed between measurements of CSAs made by both raters on the same subject. A calibration factor was calculated for transforming the measurements of Rater B, the use of which gave comparable values. ICCs using a fixed model for inter‐rater reliability were 0.963 and 0.974 for actual and trans' formed values, respectively. This study observed differences between measures obtained by different raters and recommends that the calculation and employment of a calibration factor may be useful when comparing sequential measures made by different raters.
Data assimilation for state and parameter estimation: application to morphodynamic modelling
Authors: Smith P. J. , Thornhill G. D. , Dance S. L. , Lawless A. S. , Mason D. C. , Nichols N. K.
Published: May 2012

Data assimilation is predominantly used for state estimation, combining observational data with model predictions to produce an updated model state that most accurately approximates the true system state whilst keeping the model parameters fixed. This updated model state is then used to initiate the next model forecast. Even with perfect initial data, inaccurate model parameters will lead to the growth of prediction errors. To generate reliable forecasts, we need good estimates of both the current system state and the model parameters. This article presents research into data assimilation methods for morphodynamic model state and parameter estimation. First, we focus on state estimation and describe implementation of a three‐dimensional variational (3D‐Var) data assimilation scheme in a simple 2D morphodynamic model of Morecambe Bay, UK. The assimilation of observations of bathymetry derived from synthetic aperture radar (SAR) satellite imagery and a ship‐borne survey is shown to significantly improve the predictive capability of the model over a 2‐year run. Here, the model parameters are set by manual calibration; this is laborious and is found to produce different parameter values depending on the type and coverage of the validation dataset. The second part of this article considers the problem of model parameter estimation in more detail. We explain how, by employing the technique of state augmentation, it is possible to use data assimilation to estimate uncertain model parameters concurrently with the model state. This approach removes inefficiencies associated with manual calibration and enables more effective use of observational data. We outline the development of a novel hybrid sequential 3D‐Var data assimilation algorithm for joint state‐parameter estimation and demonstrate its efficacy using an idealised 1D sediment transport model. The results of this study are extremely positive and suggest that there is great potential for the use of data assimilation‐based state‐parameter estimation in coastal morphodynamic modelling. Copyright © 2012 Royal Meteorological Society
An improved representation of the raindrop size distribution for single‐moment microphysics schemes
Authors: Abel S. J. , Boutle I. A.
Published: May 2012

We analyse observations of the size distribution of raindrops from a variety of cloud types and precipitation rates. The measurements show a transition from large raindrops observed in convective showers and frontal rainbands to higher concentrations of much smaller drizzle drops observed in stratocumulus clouds. The observations are used to develop an improved parametrization of the raindrop size distribution that better captures the observed transition for use in single‐moment microphysics schemes. Sensitivity tests are performed in both climate and numerical weather prediction versions of the Met Office Unified Model to demonstrate that the new parametrization leads to improvements in various precipitation and cloud‐related metrics. Copyright © 2012 British Crown copyright, the Met Office. Published by John Wiley & Sons Ltd.
Extending the forecast range of the UK storm surge ensemble
Authors: Flowerdew Jonathan , Mylne Ken , Jones Caroline , Titley Helen
Published: May 2012

Flooding due to coastal storm surges presents a significant threat to life and property. The UK has long had a storm surge forecasting system based on a single ‘deterministic’ simulation. This was augmented with an operational storm surge ensemble in December 2009. By producing several simulations sampling the forecast uncertainty, the ensemble estimates the probability of reaching critical water levels and thus supports a more risk‐based approach to civil protection.

The original storm surge ensemble provided forecasts out to T + 54 h, limited by the forecast range of the driving MOGREPS‐R atmospheric ensemble. Longer‐range forecasts could provide advance notice of the potential for a significant event, allowing suitable preparatory actions to be taken. This study investigates the possibility of extending the storm surge ensemble to between 5 and 7 days using atmospheric data from the lower‐resolution Met Office 15‐day ensemble (MOGREPS‐15).

Both case studies and statistical verification indicate the potential for useful forecasts out to the full 7.25 days tested. The best performance is obtained by extending the existing surge ensemble products with output from separate runs of the storm surge model, which have been driven by MOGREPS‐15 meteorology from T + 0 h. An attempt to create a single surge history for each member by switching from MOGREPS‐R to MOGREPS‐15 input at T + 54 h led to spurious oscillations in some cases, and poorer performance on several statistical measures. These issues might be improved by smoothing the discontinuity in atmospheric forcing.

Following this successful trial, the separate‐runs extension to the surge ensemble was implemented operationally in summer 2011. The study also demonstrates the benefit of online bias correction and ‘dressing’ the forecast members to account for errors which the system does not otherwise sample. The operational implementation of these features is left for future work. Copyright © 2012 British Crown copyright, the Met Office Published by John Wiley & Sons Ltd.
A Semiparametric Mixed Model Approach to Phase I Profile Monitoring
Authors: Abdel‐Salam Abdel‐Salam G. , Birch Jeffrey B. , Jensen Willis A.
Published: May 2012

Profile monitoring is an approach in quality control best used where the process data follow a profile (or curve). The majority of previous studies in profile monitoring focused on the parametric (P) modeling of either linear or nonlinear profiles, with both fixed and random effects, under the assumption of correct model specification. More recently, in the absence of an obvious P model, nonparametric (NP) methods have been employed in the profile monitoring context. For situations where a P model is adequate over part of the data but inadequate of other parts, we propose a semiparametric procedure that combines both P and NP profile fits. We refer to our semiparametric procedure as mixed model robust profile monitoring (MMRPM). These three methods (P, NP and MMRPM) can account for the autocorrelation within profiles and treat the collection of profiles as a random sample from a common population. For each approach, we propose a version of Hotelling's T2 statistic for use in Phase I analysis to determine unusual profiles based on the estimated random effects and obtain the corresponding control limits. Simulation results show that our MMRPM method performs well in making decisions regarding outlying profiles when compared to methods based on a misspecified P model or based on NP regression. In addition, however, the MMRPM method is robust to model misspecification because it also performs well when compared to a correctly specified P model. The proposed chart is able to detect changes in Phase I data and has easily calculated control limits. We apply all three methods to the automobile engine data of Amiri et al.5 and find that the NP and the MMRPM methods indicate signals that did not occur in a P approach. Copyright © 2012 John Wiley & Sons, Ltd.
Studies on the Effects of Estimator Selection in Robust Parameter Design under Asymmetric Conditions
Authors: Boylan Gregory L. , Cho Byung Rae
Published: May 2012

The primary goal of robust parameter design (RPD) is to determine the optimum operating conditions that achieve process performance targets while minimizing variability in the results. To achieve this goal, typical approaches to RPD problems use ordinary least squares methods to obtain response functions for the mean and variance by assuming that the experimental data follow a normal distribution and are relatively free of contaminants or outliers. Consequently, the most common estimators used in the initial tier of estimation are the sample mean and sample variance, as they are very good estimators when these assumptions hold. However, it is often the case that such assumed conditions do not exist in practice; notably, that inherent asymmetry pervades system outputs. If unaccounted for, such conditions can affect results tremendously by causing the quality of the estimates obtained using the sample mean and standard deviation to deteriorate. Focusing on asymmetric conditions, this paper examines several highly efficient estimators as alternatives to the sample mean and standard deviation. We then incorporate these estimators into RPD modeling and optimization approaches to ascertain which estimators tend to yield better solutions when skewness exists. Monte Carlo simulation and numerical studies are used to substantiate and compare the performance of the proposed methods with the traditional approach. Copyright © 2012 John Wiley & Sons, Ltd.
Maximum Likelihood Estimation for a Hidden Semi‐Markov Model with Multivariate Observations
Authors: Jiang Rui , Kim Michael Jong , Makis Viliam
Published: May 2012

In this paper, a parameter estimation procedure for a condition‐based maintenance model under partial observations is presented. The deterioration process of the partially observable system is modeled as a continuous‐time homogeneous semi‐Markov process. The system can be in a healthy or unhealthy operational state, or in a failure state, and the sojourn time in the operational state follows a phase‐type distribution. Only the failure state is observable, whereas operational states are unobservable. Vector observations that are stochastically related to the system state are collected at equidistant sampling times. The objective is to determine maximum likelihood estimates of the model parameters using the Expectation–Maximization (EM) algorithm. We derive explicit formulae for both the pseudo likelihood function and the parameter updates in each iteration of the EM algorithm. A numerical example is developed to illustrate the efficiency of the estimation procedure. Copyright © 2012 John Wiley & Sons, Ltd.
Basis set limit computation of dynamic polarizability at near‐resonance region
Authors: Kato Tetsuya , Yokoi Yukina , Sekino Hideo
Published: May 2012

We evaluate dynamic molecular polarizability at near‐resonance region using multiresolution multiwavelet (MRMW) basis set. The results obtained by traditional Gaussian basis sets are compared against the MRMW one. For perpendicular component, d‐aug functions seem to be necessary. Very large Gaussian basis sets beyond d‐aug‐cc‐pvqz can provide the results close to the complete space value obtained by the MRMW even for near‐resonance region. Improvement by enlargement of Gaussian functions is less systematic in the parallel component than in the perpendicular component. The competitiveness of the MRMW method against Gaussian methods in the computational efficiency for property evaluation is also discussed. © 2012 Wiley Periodicals, Inc.
Three‐time scale singular perturbation control and stability analysis for an autonomous helicopter on a platform
Authors: Esteban S. , Gordillo F. , Aracil J.
Published: May 2012

A three‐time scale singular perturbation control law is designed for a nonlinear helicopter model in vertical flight. The proposed control law is based on time scale decomposition and is able to achieve the desired altitude by selecting a desired angular velocity and the associated collective pitch angle of the blades. The stability of the system is performed by presenting a stability analysis for generic three‐time scale singularly perturbed systems, which allows to construct a composite Lyapunov function for the resultant closed‐loop system by using time scale separation and also providing mathematical expressions for the upper bounds of the singularly perturbed parameters that define the three‐time scale. Numerical results on both, the singular perturbation control strategy and the stability analysis, are also presented for the studied nonlinear highly coupled helicopter model. Copyright © 2012 John Wiley & Sons, Ltd.
Cooperative observers and regulators for discrete‐time multiagent systems
Authors: Hengster‐Movric Kristian , Lewis Frank
Published: May 2012

This paper investigates the design of distributed observers for agents with identical linear discrete‐time state‐space dynamics networked on a directed graph interaction topology. The digraph is assumed to have fixed topology and contain a spanning tree. Cooperative observer design guaranteeing convergence of the estimates of all agents to their actual states is proposed. The notion of convergence region for distributed observers on graphs is introduced. It is shown that the proposed cooperative observer design has a robustness property. Application of cooperative observers is made to the synchronization problem. A command trajectory generator and pinning control are employed for synchronizing all the agents to a desired trajectory. Complete knowledge about the agent's state is not assumed. A duality principle is shown for observers and state feedback for distributed discrete‐time systems on graph topologies. Three different observer/controller architectures are proposed for dynamic output feedback regulator design, and they are shown to guarantee convergence of the estimate to the true state and synchronization of all the agents' states to the command state trajectory. This provides design methods for cooperative regulators based on a separation principle. It is shown that the observer convergence region and feedback control synchronizing region for discrete‐time systems are inherently bounded, so that the conditions for observer convergence and state synchronization are stricter than the results for the continuous‐time counterparts. This is in part remedied by using weighting of different feedback coupling gains for every agent. Copyright © 2012 John Wiley & Sons, Ltd.