359 research outputs found

    Influential Article Review - A Comprehensive Study Distinguishing the Black and Scholes Framework

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    This paper examines business models. We present insights from a highly influential paper. Here are the highlights from this paper: The aim of the paper is to investigate the Black and Scholes model by providing an updated framework of the international literature on the topic, within the field of real option. The purpose of the research is to identify the relevant literature between 1999 and 2015, together with the most important perspectives on the Black and Scholes model as analysed by scholars, in order to provide a useful support to the academic community in their studies. The investigation was carried out only for its economic and corporate insights, with the objective of establishing the strong and weak points highlighted in the defined framework. The method used for the research was based on qualitative approach. International literature on the topic was examined through a research protocol. The research was developed by the identification of four keywords (Real Options Valuation, Real Options Assessment, Black and Scholes, Real Options Pricing) and searching them in two databases, with the purpose of obtaining a wide range of scientific contribution for the analysis. The paper presents an accurate review of the scientific contribution on the topic of the Black and Scholes model; it defines the fields of application, opportunities offered and issues relating to its application, in order to clarify the strong and weak points of the model. The Black and Scholes model of the 1970s is acknowledged to be the most widely used model for evaluating options. Our study shows that this method has been adopted by decision-makers not only for evaluating options but also in other fields. For our overseas readers, we then present the insights from this paper in Spanish, French, Portuguese, and German

    AED training and its impact on skill acquisition, retention and performance : a systematic review of alternative training methods

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    Introduction The most popular method of training in basic life support and AED use remains instructor-led training courses. This systematic review examines the evidence for different training methods of basic life support providers (laypersons and healthcare providers) using standard instructor-led courses as comparators, to assess whether alternative method of training can lead to effective skill acquisition, skill retention and actual performance whilst using the AED. Method OVID Medline (including Medline 1950-November 2010; EMBASE 1988-November 2010) was searched using “training” OR “teaching” OR “education” as text words. Search was then combined by using AND “AED” OR “automatic external defibrillator” as MESH words. Additionally, the American Heart Association Endnote library was searched with the terms “AED” and “automatic external defibrillator”. Resuscitation journal was hand searched for relevant articles. Results 285 articles were identified. After duplicates were removed, 172 references were reviewed for relevance. From this 22 papers were scrutinized and 18 were included. All were manikin studies. Four LOE 1 studies, seven LOE 2 studies and three LOE 4 studies were supportive of alternative AED training methods. One LOE 2 study was neutral. Three LOE 1 studies provided opposing evidence. Conclusion There is good evidence to support alternative methods of AED training including lay instructors, self directed learning and brief training. There is also evidence to support that no training is needed but even brief training can improve speed of shock delivery and electrode pad placement. Features of AED can have an impact on its use and further research should be directed to making devices user-friendly and robust to untrained layperson

    Particle Physics Models, Topological Defects and Electroweak Baryogenesis

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    We demonstrate the viability of electroweak baryogenesis scenarios in which the necessary departure from equilibrium is realized by the evolution of a network of topological defects. We consider several effective models of TeV physics, each addressing a fundamental particle physics problem, and in which the conditions necessary for defect-mediated electroweak baryogenesis are naturally satisfied. In each case we compare the strength of the model with that expected from scenarios in which baryogenesis proceeds with the propagation of critical bubbles.Comment: 12 pages, LaTeX, no figure

    Dynamical Breaking of CPT Symmetry in Defect Networks and Baryogenesis

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    Based on a study of {\it charge,} (C), {\it parity} (P) and {\it time reversal} (T) symmetries we show how a CP violating network of defects in the early Universe may bias baryon number production. A static network, even though it violates CP, respects CPT and hence does not bias baryon number production. On the other hand, the {\it ordering dynamics\/} of defects in a network, governed by the interplay of string tension, friction, inertia and the expansion of the Universe, results in the dynamical breakdown of CPT symmetry and may lead to a net baryon number production.Comment: 5 pages, LaTeX with prl macros, no figure

    Basic life support providers’ assessment of centre of the chest and inter-nipple line for hand position and their underlying anatomical structures

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    INTRODUCTION Effective chest compression is an integral part of good quality cardiopulmonary resuscitation. There remains uncertainty over the optimal method for identifying the correct hand position for chest compression. The aim of this study was to identify the relationship between basic life support (BLS) providers assessment of the inter-nipple line (INL) versus the centre of the chest (CoC) and to identify the anatomical structures underneath these land marks. METHOD Thirty consecutive patients having elective CT scans of the thorax were recruited and photographs of the patient fully clothed were taken in the supine position. 30 healthcare students trained in BLS were asked to mark the ‘point between the nipples’ and the ‘centre of the chest’ on each photograph in a random sequence. Corresponding points were marked on the CT images and the underlying anatomical structures were identified. RESULTS Hand positions using CoC landmark were significantly higher and were more variable than INL landmark (Measurement represented as ratio of sternal length: mean CoC 0.709, 95% CI 0.677, 0.740 vs mean INL 0.803 95% CI 0.772, 0.835; p<0.0001). Structures underneath CoC and INL hand positions were significantly different; CoC compressing predominantly the aortic arch and ascending aorta and INL compressing the left ventricle and left ventricular outflow (p<0.001). Hand positions were not significantly affected by gender of patients. CONCLUSION Both the centre of the chest landmark and inter-nipple line identify positions on the lower third of the sternum. The centre of the chest technique identifies a point that is consistently higher and more variable than the inter-nipple line. Structures compressed under both landmarks were different although the implications of this are unknown

    Mechanical chest compression devices at in-hospital cardiac arrest: A systematic review and meta-analysis

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    AIM: To summarise the evidence in relation to the routine use of mechanical chest compression devices during resuscitation from in-hospital cardiac arrest. METHODS: We conducted a systematic review of studies which compared the effect of the use of a mechanical chest compression device with manual chest compressions in adults that sustained an in-hospital cardiac arrest. Critical outcomes were survival with good neurological outcome, survival at hospital discharge or 30-days, and short-term survival (ROSC/1-h survival). Important outcomes included physiological outcomes. We synthesised results in a random-effects meta-analysis or narrative synthesis, as appropriate. Evidence quality in relation to each outcome was assessed using the GRADE system. DATA SOURCES: Studies were identified using electronic databases searches (Cochrane Central, MEDLINE, EMBASE, CINAHL), forward and backward citation searching, and review of reference lists of manufacturer documentation. RESULTS: Eight papers, containing nine studies [689 participants], were included. Three studies were randomised controlled trials. Meta-analyses showed an association between use of mechanical chest compression device and improved hospital or 30-day survival (odds ratio 2.34, 95% CI 1.42-3.85) and short-term survival (odds ratio 2.14, 95% CI 1.11-4.13). There was also evidence of improvements in physiological outcomes. Overall evidence quality in relation to all outcomes was very low. CONCLUSIONS: Mechanical chest compression devices may improve patient outcome, when used at in-hospital cardiac arrest. However, the quality of current evidence is very low. There is a need for randomised trials to evaluate the effect of mechanical chest compression devices on survival for in-hospital cardiac arrest

    The implementation of cardiac arrest treatment recommendations in English acute NHS trusts : a national survey

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    Purpose of the study: There are approximately 35 000 in-hospital cardiac arrests in the UK each year. Successful resuscitation requires integration of the medical science, training and education of clinicians and implementation of best practice in the clinical setting. In 2015, the International Liaison Committee on Resuscitation (ILCOR) published its latest resuscitation treatment recommendations. It is currently unknown the extent to which these treatment recommendations have been successfully implemented in practice in English NHS acute hospital trusts. Methods: We conducted an electronic survey of English acute NHS trusts to assess the implementation of key ILCOR resuscitation treatment recommendations in relation to in-hospital cardiac arrest practice at English NHS acute hospital trusts. Results: Of 137 eligible trusts, 73 responded to the survey (response rate 53.3%). The survey identified significant variation in the implementation of ILCOR recommendations. In particular, the use of waveform capnography (n=33, 45.2%) and ultrasound (n=29, 39.7%) was often reported to be available only in specialist areas. Post-resuscitation debriefing occurs following every in-hospital cardiac arrest in few trusts (5.5%, n=4), despite a strong ILCOR recommendation. In contrast, participation in a range of quality improvement strategies such as the National Cardiac Arrest Audit (90.4%, n=66) and resuscitation equipment provision/audit (91.8%, n=67) were high. Financial restrictions were identified by 65.8% (n=48) as the main barrier to guideline implementation. Conclusion: Our survey found that ILCOR treatment recommendations had not been fully implemented in most English NHS acute hospital trusts. Further work is required to better understand barriers to implementation

    A prescription for the asteroseismic surface correction

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    In asteroseismology, the surface effect is a disparity between the observed and the modelled oscillation frequencies. It originates from improper modelling of the surface layers in stars with solar-like oscillations. Correcting the surface effect usually requires using functions with free parameters, which are conventionally fitted to the observed frequencies. On the basis that the correction should vary smoothly across the H--R diagram, we parameterize it as a simple function of three stellar surface properties: surface gravity, effective temperature, and metallicity. We determine this function by fitting stars ranging from main-sequence dwarfs to red-giant-branch stars. The absolute amount of the surface correction increases with surface gravity, but the ratio between it and νmax\nu_{\rm max} decreases. Applying the prescription has an advantage of eliminating unrealistic surface correction, which improves parameter estimations with stellar modelling. Using two open clusters, we found that adopting the prescription can help reduce the scatter of the model-derived ages for each star in the same cluster. For an application, we provide a new revision for the Δν\Delta\nu scaling relation, using our prescription to account for the surface effect in models. The values of the correction factor, fΔνf_{\Delta\nu}, are up to 2\% smaller than those determined without the surface effect considered, suggesting decreases of up to 4\% in asteroseismic scaling radii and up to 8\% in asteroseismic scaling masses. This revision brings the asteroseismic properties into agreement with those determined from eclipsing binaries. Finally, the new correction factor and the stellar models with the corrected frequencies are made publicly available.Comment: 11 pages, 9 figures. Submitted to MNRAS. All comments (including on refs) are welcom
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