Showing papers by "Keele University published in 2006"

Performing systematic literature reviews in software engineering

Abstract: Context: Making best use of the growing number of empirical studies in Software Engineering, for making decisions and formulating research questions, requires the ability to construct an objective summary of available research evidence. Adopting a systematic approach to assessing and aggregating the outcomes from a set of empirical studies is also particularly important in Software Engineering, given that such studies may employ very different experimental forms and be undertaken in very different experimental contexts.Objectives: To provide an introduction to the role, form and processes involved in performing Systematic Literature Reviews. After the tutorial, participants should be able to read and use such reviews, and have gained the knowledge needed to conduct systematic reviews of their own.Method: We will use a blend of information presentation (including some experiences of the problems that can arise in the Software Engineering domain), and also of interactive working, using review material prepared in advance.

Spectral energy distributions and multiwavelength selection of type 1 quasars

Abstract: We present an analysis of the mid-infrared (MIR) and optical properties of type 1 (broad-line) quasars detected by the Spitzer Space Telescope. The MIR color-redshift relation is characterized to z ~ 3, with predictions to z = 7. We demonstrate how combining MIR and optical colors can yield even more efficient selection of active galactic nuclei (AGNs) than MIR or optical colors alone. Composite spectral energy distributions (SEDs) are constructed for 259 quasars with both Sloan Digital Sky Survey and Spitzer photometry, supplemented by near-IR, GALEX, VLA, and ROSAT data, where available. We discuss how the spectral diversity of quasars influences the determination of bolometric luminosities and accretion rates; assuming the mean SED can lead to errors as large as 50% for individual quasars when inferring a bolometric luminosity from an optical luminosity. Finally, we show that careful consideration of the shape of the mean quasar SED and its redshift dependence leads to a lower estimate of the fraction of reddened/obscured AGNs missed by optical surveys as compared to estimates derived from a single mean MIR to optical flux ratio.

The WASP project and the superWASP cameras

Abstract: The SuperWASP cameras are wide‐field imaging systems at the Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands, and at the Sutherland Station of the South African Astronomical Observatory. Each instrument has a field of view of some 482 deg2 with an angular scale of 13 \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} ewcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} ormalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\farcs$\end{document} 7 pixel−1, and is capable of delivering photometry with accuracy better than 1% for objects having \documentclass{aastex} \usepackage{amsbsy} \usepa...

Magnetic nanoparticles for drug delivery

Abstract: Targeting specific sites in vivo for the delivery of therapeutic compounds presents a major obstacle to the treatment of many diseases. One targeted delivery technique that has gained prominence in recent years is the use of magnetic nanoparticles. In these systems, therapeutic compounds are attached to biocompatible magnetic nanoparticles and magnetic fields generated outside the body are focused on specific targets in vivo. The fields capture the particle complex resulting in enhanced delivery to the target site. This review will focus on technical aspects of magnetic targeting as well as nanoparticle design and animal and clinical trials. Drug Dev. Res. 67:55–60, 2006. © 2006 Wiley-Liss, Inc.

Easily prepared air- and moisture-stable Pd-NHC (NHC=N-heterocyclic carbene) complexes: a reliable, user-friendly, highly active palladium precatalyst for the Suzuki-Miyaura reaction

Abstract: The synthesis of NHC-PdCl(2)-3-chloropyridine (NHC=N-heterocyclic carbene) complexes from readily available starting materials in air is described. The 2,6-diisopropylphenyl derivative was found to be highly catalytically active in alkyl-alkyl Suzuki and Negishi cross-coupling reactions. The synthesis, ease-of-use, and activity of this complex are substantial improvements over in situ catalyst generation and all current Pd-NHC complexes. The utilization of complex 4 led to the development of a reliable, easily employed Suzuki-Miyama protocol. Employing various reaction conditions allowed a large array of hindered biaryl and drug-like heteroaromatic compounds to be synthesized without difficulty.

A Theory of Network Localization

Abstract: In this paper, we provide a theoretical foundation for the problem of network localization in which some nodes know their locations and other nodes determine their locations by measuring the distances to their neighbors. We construct grounded graphs to model network localization and apply graph rigidity theory to test the conditions for unique localizability and to construct uniquely localizable networks. We further study the computational complexity of network localization and investigate a subclass of grounded graphs where localization can be computed efficiently. We conclude with a discussion of localization in sensor networks where the sensors are placed randomly

Reliability and validity in research

Abstract: This article examines reliability and validity as ways to demonstrate the rigour and trustworthiness of quantitative and qualitative research. The authors discuss the basic principles of reliability and validity for readers who are new to research.

Political opportunity structures and right‐wing extremist party success

Abstract: West European right-wing extremist parties have received a great deal of attention over the past two decades due to their electoral success. What has received less coverage, however, is the fact that these parties have not enjoyed a consistent level of electoral support across Western Europe during this period. This article puts forward an explanation of the variation in the right-wing extremist party vote across Western Europe that incorporates a wider range of factors than have been considered previously. It begins by examining the impact of socio-demographic variables on the right-wing extremist party vote. Then, it turns its attention to a whole host of structural factors that may potentially affect the extreme right party vote, including institutional, party-system and conjunctural variables. The article concludes with an assessment of which variables have the most power in explaining the uneven electoral success of right-wing extremist parties across Western Europe. The findings go some way towards challenging the conventional wisdom as to how the advance of the parties of the extreme right may be halted.

Gene therapy progress and prospects: magnetic nanoparticle-based gene delivery.

Abstract: The recent emphasis on the development of non-viral transfection agents for gene delivery has led to new physics and chemistry-based techniques, which take advantage of charge interactions and energetic processes. One of these techniques which shows much promise for both in vitro and in vivo transfection involves the use of biocompatible magnetic nanoparticles for gene delivery. In these systems, therapeutic or reporter genes are attached to magnetic nanoparticles, which are then focused to the target site/cells via high-field/high-gradient magnets. The technique promotes rapid transfection and, as more recent work indicates, excellent overall transfection levels as well. The advantages and difficulties associated with magnetic nanoparticle-based transfection will be discussed as will the underlying physical principles, recent studies and potential future applications.

Variability in use of cut-off scores and formats on the Edinburgh Postnatal Depression Scale: implications for clinical and research practice.

Abstract: Objectives: i) To highlight the increasing use in the literature of unvalidated cut-off scores on the Edinburgh Depression Scale (EDS/EPDS), as well as different wording and formatting in the scale; ii) to investigate and discuss the possible impact of using an unvalidated cut-off score; iii) to highlight possible reasons for these ‘errors’; and iv) to make recommendations to clinicians and researchers who use the EDS/EPDS. Method: A convenience sample of studies that have used unvalidated cut-off scores, or different formatting, are cited as evidence that these types of ‘errors’ are occurring fairly frequently. Examination of previous data from one of the authors is undertaken to determine the effect of using an unvalidated cut-off score. Summary: Many studies report rates of high scorers on the EDS/EPDS using different cut-off scores to the validated ones. The effect of doing this on the overall rate can be substantial. The effect of using different formatting is not known, though excluding items from the EDS/EPDS must also make a substantial difference. Recommendations: We recommend that i) the validated score of 13 or more is used when reporting on probable major depression in postnatal English-speaking women, and 15 or more when reporting on antenatal English-speaking women; ii) that the wording used is “13 or more” (or equivalent), and not other terms that may cause confusion (e.g., ‘>12’; ‘more than 12’; ‘13’ etc), iii) if a different cut-off score to the validated one is used, a clear explanation is given as to why this has been done; and iv) that the scale should be worded and formatted as originally described by its authors.

The sensory and motor roles of auditory hair cells

Abstract: Cochlear hair cells respond with phenomenal speed and sensitivity to sound vibrations that cause submicron deflections of their hair bundle. Outer hair cells are not only detectors, but also generate force to augment auditory sensitivity and frequency selectivity. Two mechanisms of force production have been proposed: contractions of the cell body or active motion of the hair bundle. Here, we describe recently identified proteins involved in the sensory and motor functions of auditory hair cells and present evidence for each force generator. Both motor mechanisms are probably needed to provide the high sensitivity and frequency discrimination of the mammalian cochlea.

A user-friendly, all-purpose Pd-NHC (NHC=N-heterocyclic carbene) precatalyst for the negishi reaction: a step towards a universal cross-coupling catalyst.

Abstract: We have developed the first user-friendly Negishi protocol capable of routinely cross-coupling all combinations of alkyl and aryl centers. The use of an easily synthesized, air stable, highly active, well-defined precatalyst PEPPSI-IPr (1; PEPPSI=pyridine-enhanced precatalyst preparation, stabilization and initiation; IPr=diisopropylphenylimidazolium derivative) substantially increases the scope, reliability, and ease-of-use of the Negishi reaction. All organohalides and routinely used pseudohalides were excellent coupling partners, with the use of chlorides, bromides, iodides, triflates, tosylates, and mesylates resulting in high yield of the coupled product. Furthermore, all reactions were performed by using general laboratory techniques, with no glove-box necessary as the precatalyst was weighed and stored in air. Utilization of this methodology allowed for the easy synthesis of an assortment of sterically encumbered biaryls and druglike heteroaromatics, demonstrating the value of the PEPPSI-IPr system. Furthermore, this is also the first time Pd-NHC (NHC=N-heterocyclic carbene) methodology has surpassed the related phosphine-ligated Negishi processes both in activity and use.

The Role of Harmonic Expectancy Violations in Musical Emotions: Evidence from Subjective, Physiological, and Neural Responses

Abstract: The purpose of the present study was to investigate the effect of harmonic expectancy violations on emotions. Subjective response measures for tension and emotionality, as well as electrodermal activity (EDA) and heart rate (HR), were recorded from 24 subjects (12 musicians and 12 nonmusicians) to observe the effect of expectancy violations on subjective and physiological measures of emotions. In addition, an electro-encephalogram was recorded to observe the neural correlates for detecting these violations. Stimuli consisted of three matched versions of six Bach chorales, which differed only in terms of one chord (harmonically either expected, unexpected or very unexpected). Musicians' and nonmusicians' responses were also compared. Tension, overall subjective emotionality, and EDA increased with an increase in harmonic unexpectedness. Analysis of the event-related potentials revealed an early negativity (EN) for both the unexpected and the very unexpected harmonies, taken to reflect the detection of the unexpected event. The EN in response to very unexpected chords was significantly larger in amplitude than the EN in response to merely unexpected harmonic events. The ENs did not differ in amplitude between the two groups but peaked earlier for musicians than for nonmusicians. Both groups also showed a P3 component in response to the very unexpected harmonies, which was considerably larger for musicians and may reflect the processing of stylistic violations of Western classical music.

A longitudinal study of ammonia, acetone and propanol in the exhaled breath of 30 subjects using selected ion flow tube mass spectrometry, SIFT-MS.

Abstract: Selected ion flow tube mass spectrometry, SIFT-MS, has been used to monitor the volatile compounds in the exhaled breath of 30 volunteers (19 males, 11 females) over a 6 month period. Volunteers provided breath samples each week between 8:45 am and 1 pm (before lunch), and the concentrations of several trace compounds were obtained. In this paper the focus is on ammonia, acetone and propanol. It was found that the concentration distributions of these compounds in breath were close to log-normal. The median ammonia level estimated as a geometric mean for all samples was 833 parts per billion (ppb) with a multiplicative standard deviation of 1.62, the values ranging from 248 to 2935 ppb. Breath ammonia clearly increased with increasing age in this volunteer cohort. The geometric mean acetone level for all samples was 477 parts per billion (ppb) with a multiplicative standard deviation of 1.58, the values ranging from 148 to 2744 ppb. The median propanol level for all samples was 18 ppb, the values ranging from 0 to 135 ppb. A weak but significant correlation between breath propanol and acetone levels is apparent in the data. The findings indicate the potential value of SIFT-MS as a non-invasive breath analysis technique for investigating volatile compounds in human health and in the diseased state.

Characterizing the Course of Low Back Pain: A Latent Class Analysis

Abstract: Understanding the course of back pain is important for clinicians and researchers, but analyses of longitudinal data from multiple time points are lacking. A prospective cohort study of consecutive back pain consulters from five general practices in the United Kingdom was carried out between 2001 and 2003 to identify groups defined by their pain pathways. Patients were sent monthly questionnaires for a year. Longitudinal latent class analysis was performed by using pain intensity scores for 342 consulters. Analysis yielded four clusters representing different pathways of back pain. Cluster 1 ("persistent mild"; n = 122) patients had stable, low levels of pain. Patients in cluster 2 ("recovering"; n = 104) started with mild pain, progressing quickly to no pain. Cluster 3 ("severe chronic"; n = 71) patients had permanently high pain. For patients in cluster 4 ("fluctuating"; n = 45), pain varied between mild and high levels. Distinctive patterns for each cluster were maintained throughout follow-up. Clusters showed statistically significant differences in disability, psychological status, and work absence (p < 0.001). This is the first time, to the authors' knowledge, that latent class analysis has been applied to longitudinal data on back pain patients. Identification of four distinct groups of patients improves understanding of the course of back pain and may provide a basis of classification for intervention.

Epidemiology of sprains of the lateral ankle ligament complex.

Abstract: Lateral ankle sprains account for 85% of all ankle sprains. This common injury is most frequently sustained during sporting activity. The ATFL is the weakest of the lateral ankle ligament complex, and is most frequently injured. Ankle sprains are often undertreated, resulting in chronic pain, muscular weakness, and instability. The consequence of this common injury for professional sports clubs is days lost in training and matches missed due to injury as well as the cost of rehabilitation. In the UK, an estimated 302,000 ankle sprains are seen each year in Accident and Emergency Departments.

Migration and the Transnational Habitus: Evidence from Canada and the Philippines

Abstract: The experiences and decisions of migrants frequently confound scholarly expectations. In particular, the transnational linkages maintained by migrants transcend the social scales at which they are often assumed to live, and the spaces in which their integration or assimilation is usually studied—the neighbourhood, the urban labour market, the national society. Studies of transnationalism have shown that immigrants maintain multistranded connections to their places of origin and that these continue to influence the lifeworlds both of migrants and of those they leave behind significantly. In this paper we suggest that these multistranded connections—incorporating social, cultural, and economic ties—can be usefully considered using Pierre Bourdieu's notion of the habitus as a heuristic framework for integrating the various dimensions of transmigrants' lives. Drawing on interviews in Canada and the Philippines, we demonstrate the ways in which economic, social, and cultural capital are accumulated, exchanged,...

Using DEA-neural network approach to evaluate branch efficiency of a large Canadian bank

Abstract: In today's economy and society, the banking industry is of great importance to every one of us. We all depend on the efficiency and quality of services that the banking industry provides. With the improvement in technology, the competition in the banking industry has become increasingly intense. Therefore, performance analyses in the banking industry attract more and more attention. This paper integrates data envelopment analysis (DEA) and neural networks (NNs) to examine the relative branch efficiency of a big Canadian bank. The results are compared with the normal DEA results. On the whole they are comparable. Furthermore, the guidance on how to improve the branch performance is given. Neural networks are also applied to do short-term efficiency prediction. Finally, the comparison between these two approaches is presented.

Senescence in human intervertebral discs

Abstract: Intervertebral discs demonstrate degenerative changes relatively early in life. Disc degeneration, in turn, is associated with back pain and disc herniation, both of which cause considerable clinical problems in the western world. Cell senescence has been linked to degenerative diseases of other connective tissues such as osteoarthritis. Thus we investigated the degree of cell senescence in different regions of discs from patients with different disc disorders. Discs were obtained from 25 patients with disc herniations; from 27 patients undergoing anterior surgery for either back pain due to degenerative disc disease (n = 25) or spondylolisthesis (n = 2) and from six patients with scoliosis. In addition, four discs were obtained post-mortem. Samples were classified as annulus fibrosus or nucleus pulposus and tissue sections were assessed for the degree of cell senescence (using the marker senescence-associated-β-galactosidase (SA-β-Gal)) and the number of cells present in clusters. There were significantly more SA-β-Gal positive cells in herniated discs (8.5% of cells) than those with degenerative disc disease, spondylolisthesis, scoliosis, or cadaveric discs (0.5% of cells; P < 0.001). There was more senescence of cells of the nucleus pulposus compared to those of the annulus fibrosus and in herniated discs a higher proportion of cells in cell clusters (defined as groups of three or more cells) were SA-β-Gal positive (25.5%) compared to cells not in clusters (4.2%, P < 0.0001). This study demonstrates an increased degree of cell senescence in herniated discs, particularly in the nucleus where cell clusters occur. These clusters have been shown previously to form via cell proliferation, which is likely to explain the increased senescence. These findings could have two important clinical implications: firstly, that since senescent cells are known to behave abnormally in other locations, they may lead to deleterious effects on the disc matrix and so contribute to the pathogenesis and secondly, cells from such tissue may not be ideal for cell therapy and repair via tissue engineering.

A systematic review of the Tardieu Scale for the measurement of spasticity.

Abstract: Background. The Tardieu Scale has been suggested a more appropriate clinical measure of spasticity than the Ashworth or modified Ashworth Scales. It appears to adhere more closely to Lance's defini...

Scalar properties in human timing: Conformity and violations

Abstract: Data from studies of timing in human participants were reviewed with respect to their conformity to the two scalar properties of timing: mean accuracy and the scalar property of variance. Results reviewed were taken from studies of temporal generalization, temporal bisection, discrimination methods, and "classical" timing tasks such as the reproduction, production, and verbal estimation of duration. Evidence for one or both scalar properties was found in many studies, including those using children and elderly participants, but systematic violations were sometimes noted. These violations occurred (a) when very short durations (< 100 ms) were timed, (b) in situations in which timing tasks varying in difficulty were compared, (c) when classical timing tasks were employed, and (d) in situations where highly practised observers exhibited unusual patterns of variance. A later section attempted to reconcile some of these violations with an underlying scalar-consistent timing mechanism.

Prevalence of radiographic osteoarthritis—it all depends on your point of view

Abstract: Objectives Knee pain and disability in older people may occur in the apparent absence of radiographic osteoarthritis. However, the view chosen to define radiographic osteoarthritis may be critical. We have investigated the prevalence and compartmental distribution of radiographic osteoarthritis in people with knee pain using different combinations of three separate radiographic views. Methods We performed a population-based study of 819 adults aged 50 yr and over with knee pain (part of the Clinical Assessment Study - Knee [CAS(K)]). Three radiographic views were obtained: weight-bearing posteroanterior (PA) semiflexed/metatarsophalangeal view; supine skyline; and supine lateral. Results Complete data for all three views were available on 777 subjects. The distribution of compartmental radiographic osteoarthritis was 314 (40%) combined tibiofemoral/patellofemoral, 186 (24%) isolated patellofemoral, 31 (4%) isolated tibiofemoral and 246 (32%) normal. Hence, the overall prevalence of radiographic osteoarthritis was 531/777 (68.3%) in this symptomatic population. Using a PA view alone (reflecting tibiofemoral osteoarthritis only) would identify 56.7% of the 531, whilst the addition of a skyline or lateral view increased this to 87.0%. When using both skyline and lateral views in addition to the PA view, 98.7% cases of radiographic osteoarthritis were identified. In addition to prevalence, compartmental distribution altered markedly when different combinations of views were used. Conclusions Multiple views detect more radiographic osteoarthritis than single views alone. When different combinations of views are used, the prevalence and compartmental distribution of osteoarthritis changes and this may alter the accepted relationship, or lack of it, between symptoms and radiographic change.

A fast hybrid algorithm for exoplanetary transit searches

Abstract: We present a fast and efficient hybrid algorithm for selecting exoplanetary candidates from wide-field transit surveys. Our method is based on the widely used SysRem and Box Least-Squares (BLS) algorithms. Patterns of systematic error that are common to all stars on the frame are mapped and eliminated using the SysRem algorithm. The remaining systematic errors caused by spatially localized flat-fielding and other errors are quantified using a boxcar-smoothing method. We show that the dimensions of the search-parameter space can be reduced greatly by carrying out an initial BLS search on a coarse grid of reduced dimensions, followed by Newton-Raphson refinement of the transit parameters in the vicinity of the most significant solutions. We illustrate the method's operation by applying it to data from one field of the SuperWASP survey, comprising 2300 observations of 7840 stars brighter than V = 13.0. We identify 11 likely transit candidates. We reject stars that exhibit significant ellipsoidal variations caused indicative of a stellar-mass companion. We use colours and proper motions from the Two Micron All Sky Survey and USNO-B1.0 surveys to estimate the stellar parameters and the companion radius. We find that two stars showing unambiguous transit signals pass all these tests, and so qualify for detailed high-resolution spectroscopic follow-up.