Showing papers by "University of Lincoln published in 2013"

A survey of keystroke dynamics biometrics

Abstract: Research on keystroke dynamics biometrics has been increasing, especially in the last decade. The main motivation behind this effort is due to the fact that keystroke dynamics biometrics is economical and can be easily integrated into the existing computer security systems with minimal alteration and user intervention. Numerous studies have been conducted in terms of data acquisition devices, feature representations, classification methods, experimental protocols, and evaluations. However, an up-to-date extensive survey and evaluation is not yet available. The objective of this paper is to provide an insightful survey and comparison on keystroke dynamics biometrics research performed throughout the last three decades, as well as offering suggestions and possible future research directions.

Optimization Problems for Fast AAM Fitting in-the-Wild

Abstract: We describe a very simple framework for deriving the most-well known optimization problems in Active Appearance Models (AAMs), and most importantly for providing efficient solutions. Our formulation results in two optimization problems for fast and exact AAM fitting, and one new algorithm which has the important advantage of being applicable to 3D. We show that the dominant cost for both forward and inverse algorithms is a few times mN which is the cost of projecting an image onto the appearance subspace. This makes both algorithms not only computationally realizable but also very attractive speed-wise for most current systems. Because exact AAM fitting is no longer computationally prohibitive, we trained AAMs in-the-wild with the goal of investigating whether AAMs benefit from such a training process. Our results show that although we did not use sophisticated shape priors, robust features or robust norms for improving performance, AAMs perform notably well and in some cases comparably with current state-of-the-art methods. We provide Matlab source code for training, fitting and reproducing the results presented in this paper at http://ibug.doc.ic.ac.uk/resources.

Validating retinal fundus image analysis algorithms: issues and a proposal.

Abstract: This paper concerns the validation of automatic retinal image analysis (ARIA) algorithms. For reasons of space and consistency, we concentrate on the validation of algorithms processing color fundus camera images, currently the largest section of the ARIA literature. We sketch the context (imaging instruments and target tasks) of ARIA validation, summarizing the main image analysis and validation techniques. We then present a list of recommendations focusing on the creation of large repositories of test data created by international consortia, easily accessible via moderated Web sites, including multicenter annotations by multiple experts, specific to clinical tasks, and capable of running submitted software automatically on the data stored, with clear and widely agreed-on performance criteria, to provide a fair comparison.

Global taxonomic diversity of living reptiles.

Abstract: Reptiles are one of the most ecologically and evolutionarily remarkable groups of living organisms, having successfully colonized most of the planet, including the oceans and some of the harshest and more environmentally unstable ecosystems on earth. Here, based on a complete dataset of all the world’s diversity of living reptiles, we analyse lineage taxonomic richness both within and among clades, at different levels of the phylogenetic hierarchy. We also analyse the historical tendencies in the descriptions of new reptile species from Linnaeus to March 2012. Although (non-avian) reptiles are the second most species-rich group of amniotes after birds, most of their diversity (96.3%) is concentrated in squamates (59% lizards, 35% snakes, and 2% amphisbaenians). In strong contrast, turtles (3.4%), crocodilians (0.3%), and tuataras (0.01%) are far less diverse. In terms of species discoveries, most turtles and crocodilians were described early, while descriptions of lizards, snakes and amphisbaenians are multimodal with respect to time. Lizard descriptions, in particular, have reached unprecedented levels during the last decade. Finally, despite such remarkably asymmetric distributions of reptile taxonomic diversity among groups, we found that the distributions of lineage richness are consistently right-skewed, with most clades (monophyletic families and genera) containing few lineages (monophyletic genera and species, respectively), while only a few have radiated greatly (notably the families Colubridae and Scincidae, and the lizard genera Anolis and Liolaemus). Therefore, such consistency in the frequency distribution of richness among clades and among phylogenetic levels suggests that the nature of reptile biodiversity is fundamentally fractal (i.e., it is scale invariant). We then compared current reptile diversity with the global reptile diversity and taxonomy known in 1980. Despite substantial differences in the taxonomies (relative to 2012), the patterns of lineage richness remain qualitatively identical, hence reinforcing our conclusions about the fractal nature of reptile biodiversity.

Are lizards feeling the heat? A tale of ecology and evolution under two temperatures

Abstract: Aim Temperature influences most components of animal ecology and life history ‐ but what kind of temperature? Physiologists usually examine the influence of body temperatures, while biogeographers and macroecologists tend to focus on environmental temperatures. We aim to examine the relationship between these two measures, to determine the factors that affect lizard body temperatures and to test the effect of both temperature measures on lizard life history. Location World-wide. Methods We used a large (861 species) global dataset of lizard body temperatures,and the mean annual temperatures across their geographic ranges to examine the relationships between body and mean annual temperatures.We then examined factors influencing body temperatures, and tested for the influence of both on ecological and life-history traits while accounting for the influence of shared ancestry. Results Body temperatures and mean annual temperatures are uncorrelated. However, accounting for activity time (nocturnal species have low body temperatures), use of space (fossorial and semi-aquatic species are ‘colder’), insularity (mainland species are ‘hotter’) and phylogeny, the two temperatures are positively correlated. High body temperatures are only associated with larger hatchlings and increased rates of biomass production. Annual temperatures are positively correlated with clutch frequency and annual longevity, and negatively correlated with clutch size, age at first reproduction and longevity.

Feasibility of an Ambulance-Based Stroke Trial, and Safety of Glyceryl Trinitrate in Ultra-Acute Stroke: The Rapid Intervention With Glyceryl Trinitrate in Hypertensive Stroke Trial (RIGHT, ISRCTN66434824)

Abstract: Background and Purpose—The practicalities of doing ambulance-based trials where paramedics perform all aspects of a clinical trial involving patients with ultra-acute stroke have not been assessed. Methods—We performed a randomized controlled trial with screening, consent, randomization, and treatment performed by paramedics prior to hospitalization. Patients with probable ultra-acute stroke ( 140 mm Hg were randomized to transdermal glyceryl trinitrate (GTN; 5 mg/24 hours) or none (blinding under gauze dressing) for 7 days with the first dose given by paramedics. The primary outcome was SBP at 2 hours. Results—Of a planned 80 patients, 41 (25 GTN, 16 no GTN) were enrolled >22 months with median age [interquartile range] 79 [16] years; men 22 (54%); SBP 168 [46]; final diagnosis: stroke 33 (80%) and transient ischemic attack 3 (7%). Time to randomization was 55 [75] minutes. After treatment with GTN versus no GTN, SBP at 2 hours was 153 [31] versus 174 [27] mm Hg, respectively, with difference −18 [30] mm Hg (P=0.030). GTN improved functional outcome with a shift in the modified Rankin Scale by 1 [3] point (P=0.040). The rates of death, 4 (16%) versus 6 (38%; P=0.15), and serious adverse events, 14 (56%) versus 10 (63%; P=0.75), did not differ between GTN and no GTN. Conclusions—Paramedics can successfully enroll patients with ultra-acute stroke into an ambulance-based trial. GTN reduces SBP at 2 hours and seems to be safe in ultra-acute stroke. A larger trial is needed to assess whether GTN improves functional outcome. Clinical Trial Registration—URL: http://www.controlled-trials.com/ISRCTN66434824/66434824. Unique identifier: 66434824. (Stroke. 2013;44:3120-3128.)

Overnight Consolidation Aids the Transfer of Statistical Knowledge from the Medial Temporal Lobe to the Striatum

Abstract: Sleep is important for abstraction of the underlying principles (or gist) which bind together conceptually related stimuli, but little is known about the neural correlates of this process. Here, we investigate this issue using overnight sleep monitoring and functional magnetic resonance imaging (fMRI). Participants were exposed to a statistically structured sequence of auditory tones then tested immediately for recognition of short sequences which conformed to the learned statistical pattern. Subsequently, after consolidation over either 30 min or 24 h, they performed a delayed test session in which brain activity was monitored with fMRI. Behaviorally, there was greater improvement across 24 h than across 30 min, and this was predicted by the amount of slow wave sleep (SWS) obtained. Functionally, we observed weaker parahippocampal responses and stronger striatal responses after sleep. Like the behavioral result, these differences in functional response were predicted by the amount of SWS obtained. Furthermore, connectivity between striatum and parahippocampus was weaker after sleep, whereas connectivity between putamen and planum temporale was stronger. Taken together, these findings suggest that abstraction is associated with a gradual shift from the hippocampal to the striatal memory system and that this may be mediated by SWS.

Coping with the cold: predictors of survival in wild Barbary macaques, Macaca sylvanus

Abstract: We report the death of 30 wild Barbary macaques, living in two groups, during an exceptionally cold and snowy winter in the Middle Atlas Mountains, Morocco. We examined whether an individual's time spent feeding, the quality and number of its social relationships, sex and rank predicted whether it survived the winter or not. The time an individual spent feeding and the number of social relationships that an individual had in the group were positive and significant predictors of survival. This is the first study to show that the degree of sociality affects an individual's chance of survival following extreme environmental conditions. Our findings support the view that sociality is directly related to an individual's fitness, and that factors promoting the establishment and maintenance of social relationships are favoured by natural selection.

The radiation of cynodonts and the ground plan of mammalian morphological diversity

Abstract: Cynodont therapsids diversified extensively after the Permo-Triassic mass extinction event, and gave rise to mammals in the Jurassic. We use an enlarged and revised dataset of discrete skeletal characters to build a new phylogeny for all main cynodont clades from the Late Permian to the Early Jurassic, and we analyse models of morphological diversification in the group. Basal taxa and epicynodonts are paraphyletic relative to eucynodonts, and the latter are divided into cynognathians and probainognathians, with tritylodonts and mammals forming sister groups. Disparity analyses reveal a heterogeneous distribution of cynodonts in a morphospace derived from cladistic characters. Pairwise morphological distances are weakly correlated with phylogenetic distances. Comparisons of disparity by groups and through time are non-significant, especially after the data are rarefied. A disparity peak occurs in the Early/Middle Triassic, after which period the mean disparity fluctuates little. Cynognathians were characterized by high evolutionary rates and high diversity early in their history, whereas probainognathian rates were low. Community structure may have been instrumental in imposing different rates on the two clades.

General practitioners’ experiences and perceptions of benzodiazepine prescribing: systematic review and meta-synthesis

Abstract: Benzodiazepines are often prescribed long-term inappropriately. We aimed to systematically review and meta-synthesise qualitative studies exploring clinicians’ experiences and perceptions of benzodiazepine prescribing to build an explanatory model of processes underlying current prescribing practices. We searched seven electronic databases for qualitative studies in Western primary care settings published in a European language between January 1990 and August 2011 analysing GP or practice nurse experiences of benzodiazepine prescribing. We assessed study quality using the Critical Appraisal Skills Programme Checklist. We analysed findings using thematic synthesis. We included eight studies from seven countries published between 1993 and 2010. Benzodiazepine prescribing decisions are complex, uncomfortable, and demanding, taken within the constraints of daily general practice. Different GPs varied in the extent to which they were willing to prescribe benzodiazepines, and individual GPs’ approaches also varied. GPs were ambivalent in their attitude towards prescribing benzodiazepines and inconsistently applied management strategies for their use. This was due to the changing context of prescribing, differing perceptions of the role and responsibility of the GP, variation in GPs’ attitudes to benzodiazepines, perceived lack of alternative treatment options, GPs’ perception of patient expectations and the doctor-patient relationship. GPs faced different challenges in managing initiation, continuation and withdrawal of benzodiazepines. We have developed a model which could be used to inform future interventions to improve adherence to benzodiazepine prescribing guidance and improve prescribing through education and training of professionals on benzodiazepine use and withdrawal, greater provision of alternatives to drugs, reflective practice, and better communication with patients.

Trust formation processes in innovative collaborations: networking as knowledge building practices

Abstract: Purpose – The purpose of this paper is to examine the practices and processes of trust building and use in collaborative networking for product innovation and to compare face to face with virtual networkingDesign/methodology/approach – Guided by a literature review and preliminary participant observation, 16 open ended interviews collected data about the processes in 11 small biotech firms These data were inductively analysed by the constant comparative method to develop explanatory themesFindings – Trust was seen as a requirement for successful collaborative innovation, but the paper identified how different dimensions of trust are located in the trust building processes Trust works by creating a platform of confidence that fosters flows of information and the exchange of tacit knowledge Two types of trust relationships, the technical and the social, work in different ways to produce different, but complementary, types of trust Virtual environments suit technical trust building but are less suited

The evolution of viviparity opens opportunities for lizard radiation but drives it into a climatic cul‐de‐sac

Abstract: Aim: Evolutionary radiations into novel areas or niches require innovative adaptations. However, rapid subsequent changes in these novel conditions might demand rapid re-adaptations to secure population persistence and prevent extinction. We propose that reptilian viviparity (live birth) is consistent with such a scenario. Using the Liolaemus lizard radiation, we investigate the hypotheses that historical invasions of cold climates have been permitted by transitions to viviparity, and that this parity mode is irreversible. Then, we investigate whether these combined factors restrict viviparous lizards to cold climates, and hence, whether viviparous species are particularly threatened by climate change. Location: South America. Methods: We employ phylogenetic analyses to investigate evolutionary transitions in reproductive modes and their consequences for environmental restrictions in viviparous lizards. We then employ climatic projections to predict the impact of climate change on the future persistence of these organisms. Results: The oviparity-to-viviparity transition is consistently associated with colonization of cold climates, and appears to be irreversible. Since viviparity seems less viable (compared with oviparity) in warm climates, species that evolve viviparity in cold climates are likely to remain adaptively constrained to such environments. Therefore, upward-poleward advances of climate warming will cause severe shifts and contractions of viviparous species ranges, threatening major extinctions over the next half century. Main conclusions: Viviparity has been largely responsible for the successful radiation of Liolaemus into cold climates, but since this adaptation is predominantly viable in these environments and is unlikely to re-evolve into oviparity, viviparity may prove to be an evolutionary dead-end for lizards facing rapid climate change. © 2013 Blackwell Publishing Ltd.

Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids.

Abstract: Adaptive radiations are central to macroevolutionary theory. Whether triggered by acquisition of new traits or ecological opportunities arising from mass extinctions, it is debated whether adaptive radiations are marked by initial expansion of taxic diversity or of morphological disparity (the range of anatomical form). If a group rediversifies following a mass extinction, it is said to have passed through a macroevolutionary bottleneck, and the loss of taxic or phylogenetic diversity may limit the amount of morphological novelty that it can subsequently generate. Anomodont therapsids, a diverse clade of Permian and Triassic herbivorous tetrapods, passed through a bottleneck during the end-Permian mass extinction. Their taxic diversity increased during the Permian, declined significantly at the Permo–Triassic boundary and rebounded during the Middle Triassic before the clade's final extinction at the end of the Triassic. By sharp contrast, disparity declined steadily during most of anomodont history. Our results highlight three main aspects of adaptive radiations: (i) diversity and disparity are generally decoupled; (ii) models of radiations following mass extinctions may differ from those triggered by other causes (e.g. trait acquisition); and (iii) the bottleneck caused by a mass extinction means that a clade can emerge lacking its original potential for generating morphological variety.

Front-of-pack nutrition labelling: are multiple formats a problem for consumers?

Abstract: Background: Nutrition labels are a potentially valuable tool to assist consumers in making healthy food choices. Front-of-pack labels are a relatively new format and are now widely used across many European countries, but it is unclear which of the many formats in use are best understood by consumers. It is also unclear whether the existence of multiple formats impedes understanding and use. This article addresses this question with findings from a study commissioned by the UK Food Standards Agency to provide evidence to inform policy decisions in this area. Methods: In-depth qualitative interviews were used to explore consumers’ decision-making processes when using two different front-of-pack label formats to judge the relative healthiness of a pair of products. Participants were presented with product pairs differently labelled and a series of structured prompts were used to access their internal dialogues and to identify any difficulties encountered. Results: The interviews revealed that making product comparisons using different label formats was challenging for participants and particularly for those product pairs where there was not an obvious answer. When the label formats on the product pairs lacked a common element, such as text, this also caused difficulties and misinterpretation. The comparisons also took time and effort that would be a deterrent in real-life situations. Conclusions: These findings indicate that the existence of multiple front-of-pack label formats in the marketplace may impede consumer comprehension and discourage use. They suggest that a single format may encourage consumers to use front-of-pack labels in making healthy food choices.

Microdosing and drug development: past, present and future

Abstract: Introduction: Microdosing is an approach to early drug development where exploratory pharmacokinetic data are acquired in humans using inherently safe sub-pharmacologic doses of drug. The first publication of microdose data was 10 years ago and this review comprehensively explores the microdose concept from conception, over the past decade, up until the current date. Areas covered: The authors define and distinguish the concept of microdosing from similar approaches. The authors review the ability of microdosing to provide exploratory pharmacokinetics (concentration-time data) but exclude microdosing using positron emission tomography. The article provides a comprehensive review of data within the peer-reviewed literature as well as the latest applications and a look into the future, towards where microdosing may be headed. Expert opinion: Evidence so far suggests that microdosing may be a better predictive tool of human pharmacokinetics than alternative methods and combination with physiologically based ...

The Effect of Climatic Factors on the Activity Budgets of Barbary Macaques (Macaca sylvanus)

Abstract: Climatic conditions can significantly affect the behavior of animals and constrain their activity or geographic distribution. Barbary macaques (Macaca sylvanus) are one of the few primates that live outside the tropics. Here we analyze if and how the activity budgets of Barbary macaques are affected by climatic variables, i.e., air temperature, relative humidity, rainfall, and snow coverage. We collected scan sampling data on the activity budgets of four groups of macaques living in the Middle Atlas Mountains of Morocco from June 2008 to January 2011. This habitat is characterized by extreme seasonal changes, from cold and snowy winters to hot and dry summers. The activity budgets of the macaques differed across months but not across the time of day (with the exception of time spent feeding). The monkeys spent significantly more time feeding or foraging when there was no snow than when snow coverage was moderate or major. Daily rainfall was positively related to resting time and negatively to time spent moving or in social behavior. Air temperature was negatively related to time spent feeding or foraging. Finally, time spent on social behavior was significantly lower when relative humidity was high. These data indicate that environmental factors significantly affect the time budgets of endangered Barbary macaques, a species that has been little studied in the wild. Our findings support previous studies on temperate primates in showing that snow coverage can have negative consequences on the feeding ecology and survival of these species.

Mediterranean diet- and exercise-induced improvement in age-dependent vascular activity

Abstract: The aging effect on microvascular integrity, marked by endothelial dysfunction and reduction in exercise tolerance, is a major cause of CVD (cardiovascular disease). Improved dietary habits, known to reduce morbidity and mortality, are also known to attenuate those aging effects. The present study investigated the effects of combined MD (Mediterranean diet) and exercise intervention on lower- and upper-limb cutaneous microvascular functions in an older healthy population. A total of 22 sedentary healthy participants (age, 55±4 years) underwent cardiopulmonary exercise tolerance test, and were assessed for their upper- and lower-limb vascular endothelial CVC (cutaneous vascular conductance) using LDF (laser Doppler fluximetry) with endothelium-dependent [ACh (acetylcholine chloride)] and -independent [SNP (sodium nitroprusside)] vasodilation. Participants were then randomized into two groups: MD and non-MD, and followed an 8-week intervention programme, which included discontinuous treadmill running based on each individual's exertion, twice per week. Exercise training improved CVC in both groups (e.g. 0.42±0.19 compared with 1.50±1.05 and 0.47±0.26 compared with 1.15±0.59 at 1000 μCb for MD and non-MD respectively; P<0.001). This was also combined by improvement in the exercise tolerance indicated by increased VT (ventilatory threshold) in both groups [12.2±2.8 compared with 14.8±2.8 ml·(kg of body weight)(-1)·min(-1) and 11.7±2.7 compared with 14.6±3.2 ml·(kg of body weight)(-1)·min(-1) for MD and non-MD groups respectively; P<0.05]. However, the MD group showed greater improvement in endothelium-dependent vasodilation than non-MD [ANCOVA (analyses of co-variance), P=0.02]. The results of the present study suggest that compliance with MD, combined with regular moderate exercise, improves age-provoked microcirculatory endothelial dysfunction and increases exercise tolerance, both responsible for reducing cardiovascular risk in this age group.

The assessment of practical work in school science

Abstract: This article reviews how practical work, including practical skills, is currently summatively assessed in school science in a number of countries and makes comparisons with how other subjects, such as music and modern foreign languages, summatively assess skills. Whilst practical skills in school science are clearly valued as being of importance, there is a lack of clarity as to what these skills actually are and how they might, most effectively, be validly assessed. Countries vary greatly in the extent to which they employ what we term ‘Direct Assessment of Practical Skills’ (DAPS) or ‘Indirect Assessment of Practical Skills’ (IAPS). Each of these approaches has advantages and disadvantages but we conclude that too great a reliance on IAPS reduces the likelihood that practical work will be taught and learnt as well as it might be.

History on Television

Abstract: In recent years non-fiction history programmes have flourished on television. This interdisciplinary study of history programming identifies and examines different genres employed by producers and tracks their commissioning, production, marketing and distribution histories. With comparative references to other European nations and North America, the authors focus on British history programming over the last two decades and analyse the relationship between the academy and media professionals. They outline and discuss often-competing discourses about how to ‘do’ history and the underlying assumptions about who watches history programmes. History on Television considers recent changes in the media landscape, which have affected to a great degree how history in general, and whose history in particular, appears onscreen. Through a number of case studies, using material from interviews by the authors with academic and media professionals, the role of the ‘professional’ historian and that of media professionals – commissioning editors and producer/directors - as mediators of historical material and interpretations is analysed, and the ways in which the ‘logics of television’ shape historical output are outlined and discussed. Building on their analysis, Ann Gray and Erin Bell ask if history on television fulfils its potential to be a form of public history through offering, as it does, a range of interpretations of the past to and originating from or including those not based in the academy. Through consideration of the representation, or absence, of the diversity of British identity – gender, ethnicity and race, social status and regional identities – the authors substantially extend the scope of existing scholarship into history on television History on Television will be essential reading for all those interested in the complex processes involved in the representation of history on television.

The incidence rate of female breast cancer in Saudi Arabia: an observational descriptive epidemiological analysis of data from Saudi Cancer Registry 2001-2008.

Abstract: Background: This study presents descriptive epidemiological data related to breast cancer cases diagnosed from 2001 to 2008 among Saudi women, including the frequency and percentage of cases, the crude incidence rate (CIR), and the age-standardized incidence rate (ASIR), adjusted by the region and year of diagnosis. Methods: This is a retrospective descriptive epidemiological study of all Saudi female breast cancer cases from 2001 to 2008. The statistical analyses were conducted using descriptive statistics, a linear regression model, and analysis of variance with the Statistical Package for the Social Sciences version 20 (IBM Corporation, Armonk, NY, USA). Results: A total of 6,922 female breast cancer cases were recorded in the Saudi Cancer Registry from 2001 to 2008. The highest overall percentages (38.6% and 31.2%) of female breast cancer cases were documented in women who were 30–44 and 45–59 years of age, respectively. The eastern region of Saudi Arabia had the highest overall ASIR, at 26.6 per 100,000 women, followed by Riyadh at 20.5 and Makkah at 19.4. Jazan, Baha, and Asir had the lowest average ASIRs, at 4.8, 6.1, and 7.3 per 100,000 women, respectively. The region of Jouf (24.2%; CIR 11.2, ASIR 17.2) had the highest changes in CIR and ASIR from 2001 to 2008. While Qassim, Jazan and Tabuk recorded down-trending rates with negative values. Conclusion: There was a significant increase in the CIRs and ASIRs for female breast cancer between 2001 and 2008. The majority of breast cancer cases occurred among younger women. The region of Jouf had the greatest significant differences of CIR and ASIR during 2001 to 2008. Jazan, Baha, and Najran had the lowest average CIRs and ASIRs of female breast cancer, whereas the linear trend upward is a concern in certain regions, such as the eastern region, Makkah, and Riyadh. However, further analytical epidemiological research is needed to identify the potential risk factors involved in the increase in the prevalence of breast cancer among Saudi women.

Reducing Waste to Landfill in the UK: Identifying Impediments and Critical Solutions

Abstract: Purpose – The UK construction industry produces up to one third of all waste to landfill. This study aims to identify specific project practices impeding the reduction of waste in construction projects as well as uncovering potential waste solutions throughout the project delivery process. The rationale being that for such a drastic reduction in waste to landfill, holistic and extensive measures would be required.Design/methodology/approach – A two‐way methodological approach was used. This comprised qualitative unstructured interviews and a quantitative questionnaire survey of three major stakeholders in the UK construction industry: clients, architects and contractors.Findings – Design factors remain the major cause of impediments to waste reduction to landfill. Critical impediments include clients making waste prevention a top priority in projects, overly complex designs, waste taking a low priority compared to project time and costs, lack of concerns by designers for buildability, among others. Critic...

The trade-off between taxi time and fuel consumption in airport ground movement

Abstract: Environmental issues play an important role across many sectors. This is particularly the case in the air transportation industry. One area which has remained relatively unexplored in this context is the ground movement problem for aircraft on the airport’s surface. Aircraft have to be routed from a gate to a runway and vice versa and a key area of study is whether fuel burn and environmental impact improvements will best result from purely minimising the taxi times or whether it is also important to avoid multiple acceleration phases. This paper presents a newly developed multi-objective approach for analysing the trade-off between taxi time and fuel consumption during taxiing. The approach consists of a combination of a graph-based routing algorithm and a population adaptive immune algorithm to discover different speed profiles of aircraft. Analysis with data from a European hub airport has highlighted the impressive performance of the new approach. Furthermore, it is shown that the trade-off between taxi time and fuel consumption is very sensitive to the fuel-related objective function which is used.

The use and value of Bernstein’s work in studying (in)equalities in undergraduate social science education

Abstract: This paper illustrates how critical use of Basil Bernstein's theory illuminates the mechanisms by which university knowledge, curriculum and pedagogy both reproduce and interrupt social inequalities. To this end, empirical examples are selected from the findings of the ESRC-funded project ‘Pedagogic Quality and Inequality in University First Degrees' (RES-062-23-1438, November 2008–January 2012). The project investigated sociology-related social science degrees in four social science departments in universities in different positions in influential UK higher education league tables. A Bernsteinian lens throws fresh light on how university education might contribute to a more egalitarian society.

“Having sex” as a graded and hierarchical construct: a comparison of sexual definitions among heterosexual and lesbian emerging adults in the U.K.

Abstract: Research into definitions of “having sex” has tended to employ a dichotomous response design (following Sanders & Reinisch, 1999). However, conceptions of sexual activity may be far less clear-cut (c.f. Faulkner, 2003; Peterson & Muehlenhard, 2007). More refinement is also needed regarding the impact of sexual orientation on the construction of what counts as sex. This research employed a continuous response design, asking 124 emerging adults (40 male heterosexuals, 42 female heterosexuals, & 42 lesbians) to judge 13 sexual acts using a graded, six-point scale. Overall, there was substantial agreement that intercourse (vaginal and anal) was “definitely,” and kissing “definitely not,” sex. However, across the various acts, participants also consistently made use of options between these extremes, such that a clear hierarchy of sexual behaviors emerged. The lesbian group considered a range of forms of genital stimulation to be significantly more constitutive of sex than either heterosexual group, while judg...

The antecedents of travellers’ e-satisfaction and intention to buy airline tickets online: A conceptual model

Abstract: Purpose – The purpose of this paper is to utilise the existing theories on consumer behaviour and scales within web quality to develop a framework for measuring travellers’ web satisfaction and willingness to purchase tickets through airlines’ web sites. Design/methodology/approach – The paper is discursive, based on the analysis and synthesis of literature pertaining to e-consumer behaviour, web quality and travel and tourism streams. Gaps in the previous research have been identified and a conceptual framework is consequently proposed. In addition, further research and methodology is suggested. Findings – The paper proposes a conceptual framework that can measure consumers’ electronic satisfaction and intention to purchase tickets from airlines’ web sites. The framework includes nine constructs: information quality, system quality, perceived usefulness, perceived ease of use, e-trust, airline reputation, price perception, e-satisfaction and intention to purchase. Research limitations/implications – As a...