Keele University

About: Keele University is a education organization based out in Newcastle-under-Lyme, United Kingdom. It is known for research contribution in the topics: Population & Stars. The organization has 11318 authors who have published 26323 publications receiving 894671 citations. The organization is also known as: Keele University.

What makes the Peregrine soliton so special as a prototype of freak waves

Abstract: The formation of breathers as prototypes of freak waves is studied within the framework of the classic ‘focussing’ nonlinear Schrodinger (NLS) equation. The analysis is confined to evolution of localised initial perturbations upon an otherwise uniform wave train. For a breather to emerge out of an initial hump, a certain integral over the hump, which we refer to as the “area”, should exceed a certain critical value. It is shown that the breathers produced by the critical and slightly supercritical initial perturbations are described by the Peregrine soliton which represents a spatially localised breather with only one oscillation in time and thus captures the main feature of freak waves: a propensity to appear out of nowhere and disappear without trace. The maximal amplitude of the Peregrine soliton equals exactly three times the amplitude of the unperturbed uniform wave train. It is found that, independently of the proximity to criticality, all small-amplitude supercritical humps generate the Peregrine solitons to leading order. Since the criticality condition requires the spatial scale of the initially small perturbation to be very large (inversely proportional to the square root of the smallness of the hump magnitude), this allows one to predict a priori whether a freak wave could develop judging just by the presence/absence of the corresponding scales in the initial conditions. If a freak wave does develop, it will be most likely the Peregrine soliton with the peak amplitude close to three times the background level. Hence, within the framework of the one-dimensional NLS equation the Peregrine soliton describes the most likely freak-wave patterns. The prospects of applying the findings to real-world freak waves are also discussed.

Individual Participant Data (IPD) Meta-analyses of Randomised Controlled Trials: Guidance on Their Use

Abstract: Jayne Tierney and colleagues offer guidance on how to spot a well-designed and well-conducted individual participant data meta-analysis.

Diagnosis of Stroke-Associated Pneumonia: Recommendations From the Pneumonia in Stroke Consensus Group

Abstract: Background and Purpose—Lower respiratory tract infections frequently complicate stroke and adversely affect outcome. There is currently no agreed terminology or gold-standard diagnostic criteria for the spectrum of lower respiratory tract infections complicating stroke, which has implications for clinical practice and research. The aim of this consensus was to propose standardized terminology and operational diagnostic criteria for lower respiratory tract infections complicating acute stroke. Methods—Systematic literature searches of multiple electronic databases were undertaken. An evidence review and 2 rounds of consensus consultation were completed before a final consensus meeting in September 2014, held in Manchester, United Kingdom. Consensus was defined a priori as ≥75% agreement between the consensus group members. Results—Consensus was reached for the following: (1) stroke-associated pneumonia (SAP) is the recommended terminology for the spectrum of lower respiratory tract infections within the fi...

Fast adaptation of mechanoelectrical transducer channels in mammalian cochlear hair cells

Abstract: Outer hair cells are centrally involved in the amplification and frequency tuning of the mammalian cochlea, but evidence about their transducing properties in animals with fully developed hearing is lacking Here we describe measurements of mechanoelectrical transducer currents in outer hair cells of rats between postnatal days 5 and 18, before and after the onset of hearing Deflection of hair bundles using a new rapid piezoelectric stimulator evoked transducer currents with ultra-fast activation and adaptation kinetics Fast adaptation resembled the same process in turtle hair cells, where it is regulated by changes in stereociliary calcium It is argued that sub-millisecond transducer adaptation can operate in outer hair cells under the ionic, driving force and temperature conditions that prevail in the intact mammalian cochlea

Detecting binocular half-occlusions: empirical comparisons of five approaches

Abstract: Binocular half-occlusion points are those that are visible in one of the two views provided by a binocular imaging system. Due to their importance in binocular matching as well as, subsequent interpretation tasks, a number of approaches have been developed for dealing with such points. In the current paper, we consider five methods that explicitly detect half-occlusions and report on a more uniform comparison than has previously been performed. Taking a disparity image and its associated match goodness image as input, we generate images that show the half-occluded points in the underlying scene. We quantitatively and qualitatively compare these methods under a variety of conditions.