Classical Electromagnetic Fields from Quantum Sources in Heavy-Ion Collisions

Electromagnetic fields are generated in high energy nuclear collisions by spectator valence protons. These fields are traditionally computed by integrating the Maxwell equations with point sources. One might expect that such an approach is valid at distances much larger than the proton size and thus such a classical approach should work well for almost the entire interaction region in the case of heavy nuclei. We argue that, in fact, the contrary is true: due to the quantum diffusion of the proton wave function, the classical approximation breaks down at distances of the order of the system size. We compute the electromagnetic field created by a charged particle described initially as a Gaussian wave packet of width 1 fm and evolving in vacuum according to the Klein-Gordon equation. We completely neglect the medium effects. We show that the dynamics, magnitude and even sign of the electromagnetic field created by classical and quantum sources are different.Comment: 12 pages, 4 figures. V2: a numerical error corrected, figures improved, other minor improvement

Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs

Extinct archosaurs, including many non-avian dinosaurs, exhibit relatively simply shaped condylar regions in their appendicular bones, suggesting potentially large amounts of unpreserved epiphyseal (articular) cartilage. This “lost anatomy” is often underappreciated such that the ends of bones are typically considered to be the joint surfaces, potentially having a major impact on functional interpretation. Extant alligators and birds were used to establish an objective basis for inferences about cartilaginous articular structures in such extinct archosaur clades as non-avian dinosaurs. Limb elements of alligators, ostriches, and other birds were dissected, disarticulated, and defleshed. Lengths and condylar shapes of elements with intact epiphyses were measured. Limbs were subsequently completely skeletonized and the measurements repeated. Removal of cartilaginous condylar regions resulted in statistically significant changes in element length and condylar breadth. Moreover, there was marked loss of those cartilaginous structures responsible for joint architecture and congruence. Compared to alligators, birds showed less dramatic, but still significant changes. Condylar morphologies of dinosaur limb bones suggest that most non-coelurosaurian clades possessed large cartilaginous epiphyses that relied on the maintenance of vascular channels that are otherwise eliminated early in ontogeny in smaller-bodied tetrapods. A sensitivity analysis using cartilage correction factors (CCFs) obtained from extant taxa indicates that whereas the presence of cartilaginous epiphyses only moderately increases estimates of dinosaur height and speed, it has important implications for our ability to infer joint morphology, posture, and the complicated functional movements in the limbs of many extinct archosaurs. Evidence suggests that the sizes of sauropod epiphyseal cartilages surpassed those of alligators, which account for at least 10% of hindlimb length. These data suggest that large cartilaginous epiphyses were widely distributed among non-avian archosaurs and must be considered when making inferences about locomotor functional morphology in fossil taxa

A feasibility study with embedded pilot randomised controlled trial and process evaluation of electronic cigarettes for smoking cessation in patients with periodontitis

Background Tobacco smoking is a major risk factor for several oral diseases, including periodontitis, and electronic cigarettes (e-cigarettes) are increasingly being used for smoking cessation. This study aimed to assess the viability of delivering and evaluating an e-cigarette intervention for smoking cessation within the dental setting, prior to a definitive study. Methods A feasibility study, comprising a pilot randomised controlled trial and qualitative process evaluation, was conducted over 22 months in the Newcastle upon Tyne Hospitals NHS Dental Clinical Research Facility, UK. The pilot trial comprised a two-armed, parallel group, individually randomised, controlled trial, with 1:1 allocation. Participant eligibility criteria included being a tobacco smoker, having periodontitis and not currently using an e-cigarette. All participants received standard non-surgical periodontal therapies and brief smoking cessation advice. The intervention group additionally received an e-cigarette starter kit with brief training. Proposed outcomes for a future definitive trial, in terms of smoking behaviour and periodontal/oral health, were collected over 6 months to assess data yield and quality and estimates of parameters. Analyses were descriptive, with 95% confidence intervals presented, where appropriate. Results Eighty participants were successfully recruited from a range of dental settings. Participant retention was 73% (n = 58; 95% CI 62–81%) at 6 months. The e-cigarette intervention was well received, with usage rates of 90% (n = 36; 95% CI 77–96%) at quit date. Twenty percent (n = 8; 95% CI 11–35%) of participants in the control group used an e-cigarette at some point during the study (against advice). The majority of the outcome measures were successfully collected, apart from a weekly smoking questionnaire (only 30% of participants achieved ≥ 80% completion). Reductions in expired air carbon monoxide over 6 months of 6 ppm (95% CI 1–10 ppm) and 12 ppm (95% CI 8–16 ppm) were observed in the control and intervention groups, respectively. Rates of abstinence (carbon monoxide-verified continuous abstinence for 6 months) for the two groups were 5% (n = 2; 95% CI 1–17%; control group) and 15% (n = 6; 95% CI 7–29%; intervention group). Conclusions Data suggest that a definitive trial is feasible and that the intervention may improve smoking quit rates. Insights were gained into how best to conduct the definitive trial and estimates of parameters to inform design were obtained

Developing general cultural awareness in a monocultural English as a foreign language context in a Mexican university: a wiki-based critical incident approach

© 2013 Association for Language Learning. This article explores what the ‘intercultural turn’ might mean in the case of teaching English to speakers of other languages (TESOL). The discussion is contextualised in what has been termed the ‘expanding circle’ of English and focuses on an English as a foreign language (EFL) class in a Mexican university, a context where the full implications of a shift from EFL to English as a lingua franca (ELF) have yet to be addressed. We consider how the intercultural turn might be understood in this Mexican context and then present the rationale for, and design of, a technology-based (wiki) extra-curricular pilot project which adopted less of an EFL/cultural and more of an ELF/intercultural approach. We evaluate the evidence from this small-scale project in terms of students\u27 developing general cultural awareness and suggest that this type of project, an example of the intercultural turn, might be more widely applicable in similar ‘expanding circle’ EFL contexts

Traversing the Inner Seas: Contacts and Continuity in and around Scotland, the Hebrides, and the North of Ireland

Throughout the medieval period, the ‘Inner Seas’ linking Scotland, the Hebrides, and the north of Ireland represented a confluence and crucible of identity. The region’s myriad islands served as stepping stones in a maritime network across which people, property, and perceptions travelled freely and purposefully. Encompassing three main themes, ten authors, and a multitude of interdisciplinary insights, this peer-reviewed volume represents some of the foremost research from the most recent residential conferences of the Scottish Society for Northern Studies, exploring the turbulent history and legacy of this interconnected seascape as both centre and periphery

Top of the Pods - In search of a podcasting “podagogy” for language learning

The popularization of portable media players such as the iPod, and the delivery of audio and video content through content management software such as iTunes mean that there is a wealth of language learning resources freely available to users who may download them and use them anywhere at any time. These resources vary greatly in quality and follow different approaches to learning. This paper provides a taxonomy of podcast resources, reviews materials in the light of Second Language Acquisition theories, argues for better design, and outlines directions for future research

Are recovery stories helpful for women with eating disorders? A pilot study and commentary on future research

Background: Anecdotally it is well known that eating disorder memoirs are popular with people with anorexia nervosa and recovery stories are readily available online. However, no research to date has empirically explored whether such stories are helpful for current sufferers. The aim of the current pilot study was to explore the efficacy of recovery narratives as a means of improving motivation and self-efficacy and to qualitatively explore patient perspectives of such stories. Method: Fifty-seven women with anorexia nervosa and subclinical anorexia nervosa participated in this online study. Participants were randomised to either receive recovery stories or to a wait-list control group. After completing baseline measures, participants read five stories about recovery, and completed post-intervention measures two weeks later. Results: The quantitative results indicated that reading stories of recovery had no effect on motivation and self-efficacy over a two-week period. In contrast, the qualitative results showed that the stories generated thoughts about the possibility of recovery and the majority indicated they would recommend them to others. Conclusions: This study adds to a growing body of research exploring the integration of voices of lived experience into treatment approaches. Future research should focus on 1) identifying for whom and at which stage of illness recovery stories might be helpful; 2) the mechanism via which they might operate; and 3) the most helpful way of presenting such stories