Non-linear growth of short-wave instabilities in a Batchelor vortex pair

Recent investigations have identified a variety of instability modes which may develop to enhance dispersion of co- and counter-rotating vortex pairs. This has application in the aviation industry, where an aircraft’s trailing vortices pose a significant hazard for other nearby aircraft. Batchelor vortices adopt the radial velocity field of Lamb – Oseen vortices, but with an axial velocity component through the core of the vortex, and are often used to represent vortices within an aircraft wake. Recently, the vortex swirl ratio of the Batchelor vortex pair has been identified as a key parameter which may be used to select the mode of instability which develops. Several modes have recently been identified via linear stability analysis. This study extends these prior investigations by considering the non-linear growth of the three-dimensional instabilities acting to disperse the vortex pair. Here, we validate prior linear instability investigations, and compare and contrast the relative ability of several instability modes to achieve improved vortex dispersion. The study has been conducted using a high-order, three-dimensional spectral element method to solve the timedependent incompressible Navier – Stokes equations. The study is conducted at a circulation Reynolds number of 2 800

Strain-rate development between a co-rotating Lamb-Oseen vortex pair of unequal strength.

To date, several investigations have considered the prospect of enhanced dissipation of a vortex pair due to elliptic (short wave) instabilities. Recent studies indicate that these modes have the potential to significantly reduce the time taken to dissipate vortex pairs. This has generated interest in the aviation industry, where aircraft trailing wakes pose a significant hazard for nearby aircraft. Of note, recent studies have indicated that the growth rate of these short-wave instability modes depends strongly on the strain-rate developed within the core of each vortex. This strainrate has been shown to develop naturally simply due to the presence of both vortices. Studies to date have concentrated on vortex pairs where each vortex has the same magnitude of circulation. We extend this by varying the circulation ratio of the two vortices; the circulation of one vortex is varied while the circulation of the other remains constant. The effect on the strain-rate which develops within each core is considered. Of particular interest are the time-scales involved in both the strain-rate development and in the twodimensional merging process, as sufficient time is required for short-wavelength instabilities to occur prior to merging for the process to successfully reduce dissipation time. A spectral-element method is used to conduct the DNS investigation at a circulation Reynolds number of ReΓ = 20,000

Nonlinear resonant tunneling in systems coupled to quantum reservoirs

An adiabatic approximation in terms of instantaneous resonances is developed to study the steady-state and time-dependent transport of interacting electrons in biased resonant tunneling heterostructures. The resulting model consists of quantum reservoirs coupled to regions where the system is described by nonlinear ordinary differential equations and has a general conceptual interest.Comment: 4 pages, 3 postscript figure

Creation of solitons and vortices by Bragg reflection of Bose-Einstein condensates in an optical lattice

We study the dynamics of Bose-Einstein condensates in an optical lattice and harmonic trap. The condensates are set in motion by displacing the trap and initially follow simple semiclassical paths, shaped by the lowest energy band. Above a critical displacement, the condensate undergoes Bragg reflection. For high atom densities, the first Bragg reflection generates a train of solitons and vortices, which destabilize the condensate and trigger explosive expansion. At lower densities, soliton and vortex formation requires multiple Bragg reflections, and damps the center-of-mass motion.Comment: 5 pages including 5 figures (for higher resolution figures please email the authors

Improving patient experience and safety at transitions of care through the Your Care Needs You (YCNY) intervention: a study protocol for a cluster randomised controlled feasibility trial

Background: Patients, particularly older people, often experience safety issues when transitioning from hospital to home. Although the evidence is currently equivocal as to how we can improve this transition of care, interventions that support patient involvement may be more effective. The ‘Your Care Needs You’ (YCNY) intervention supports patients to ‘know more’ and ‘do more’ whilst in hospital in order that they better understand their health condition and medications, maintain their daily activities, and can seek help at home if required. The intervention aims to reduce emergency hospital readmissions and improve safety and experience during the transition to home. Methods: As part of the Partners At Care Transitions (PACT) programme of research, a multi-centred cluster randomised controlled trial (cRCT) will be conducted to explore the feasibility of the YCNY intervention and trial methodology. Data will be used to refine the intervention and develop a protocol for a definitive cRCT. Ten acute hospital wards (the clusters) from varying medical specialties including older peoples’ medicine, trauma and orthopaedics, cardiology, intermediate care, and stroke will be randomised to deliver YCNY or usual care on a 3:2 basis. Up to 200 patients aged 75 years and over and discharged to their own homes will be recruited to the study. Patients will complete follow-up questionnaires at 5-, 30-, and 90-days post-discharge and readmission data up to 90-days post-discharge will be extracted from their medical records. Study outcomes will include measures of feasibility (e.g. screening, recruitment, and retention data) and processes required to collect routine data at a patient and ward level. In addition, interviews and observations involving up to 24 patients/carers and 28 staff will be conducted to qualitatively assess the acceptability, usefulness, and feasibility of the intervention and implementation package to patients and staff. A separate sub-study will be conducted to explore how accurately primary outcome data (30-day emergency hospital readmissions) can be gathered for the definitive cRCT. Discussion: This study will establish the feasibility of the YCNY intervention which aims to improve safety and experience during transitions of care. It will identify key methodological and implementation issues that need to be addressed prior to assessing the effectiveness of the YCNY intervention in a definitive cluster randomised controlled trial

Not in my back yard! Sports stadia location and the property market

In recent years sports stadia have been built in the UK, not only for their intended sporting purpose but with the twin aim of stimulating economic and physical regeneration. However, proposals to locate stadia in urban areas often prompt a negative reaction from local communities, fearing a decline in property prices. This paper will use a case study of the Millennium Stadium in Cardiff and the City of Manchester Stadium to illustrate that in contrast to this widely held belief, sports stadia can actually enhance the value of residential property. Furthermore, it will argue that stadia also contribute indirectly to property value through the creation of pride, confidence and enhanced image of an area.</p

The Dynamic Characteristics of a High Pressure Turbine Stage in a Transient Wind Tunnel

ABSTRACT A new transient facility for the study of time averaged and unsteady aerodynamics and heat transfer in a high pressure turbine was recently commissioned. During the facility design a high priority was placed on ease of access to the turbine blading to facilitate the development of blade mounted instrumentation. The turbine disc was cantilevered on a shaft by a thin annular link, with the shaft passing back through the disc to a single row and matched pair of relatively closely spaced bearings. The bearings were originally designed for use in a marine gas turbine. Due to the facility&apos;s novel mode of operation the bearings were working well beyond some of their original design limits, primarily due to the high turbine acceleration and the high speed/low load condition at the end of facility operation. During the facility design a programme of work was undertaken to predict its dynamic performance. This was continued during commissioning to measure actual facility performance. In this paper the predicted dynamic performance of the disc/shaft assembly and its bearing system are presented. The programme of work undertaken during the facility commissioning phase to ascertain actual dynamic performance is described, and the results discussed. Finally, the technique developed to field balance the rotating assembly following changes to blade instrumentation is described

Improving the safety and experience of transitions from hospital to home: a cluster randomised controlled feasibility trial of the ’Your Care Needs You’ intervention versus usual care

Background: The ‘Your Care Needs You’ (YCNY) intervention aims to increase the safety and experience of transitions for older people through greater patient involvement during the hospital stay. Methods: A cluster randomised controlled feasibility trial was conducted on NHS inpatient wards (clusters) where ≥ 40% of patients were routinely ≥ 75 years. Wards were randomised to YCNY or usual care using an unequal allocation ratio (3:2). We aimed to recruit up to 20 patients per ward. Follow-up included routine data collection and questionnaires at 5-, 30-, and 90-days post-discharge. Eligible patients were ≥ 75 years, discharged home, stayed overnight on participating wards, and could read and understand English. The trial assessed the feasibility of delivering YCNY and the trial methodology through recruitment rates, outcome completion rates, and a qualitative evaluation. The accuracy of using routinely coded data for the primary outcome in the defnitive trial was assessed by extracting discharge information for up to ten nonindividual consenting patients per ward. Results: Ten wards were randomised (6 intervention, 4 control). One ward withdrew, and two wards were unable to deliver the intervention. Seven-hundred twenty-one patients were successfully screened, and 161 were recruited (95 intervention, 66 control). The patient post-discharge attrition rate was 17.4% (n = 28). Primary outcome data were gathered for 91.9% of participants with 75.2% and 59.0% providing secondary outcome data at 5 and 30 days post-discharge respectively. Item completion within questionnaires was generally high. Post-discharge follow-up was terminated early due to the COVID-19 pandemic afecting 90-day response rates (16.8%). Data from 88 nonindividual consenting patients identifed an error rate of 15% when using routinely coded data for the primary outcome. No unexpected serious adverse events were identifed

What can patients tell us about the quality and safety of hospital care? Findings from a UK multicentre survey study

Background Patient safety measurement remains a global challenge. Patients are an important but neglected source of learning; however, little is known about what patients can add to our understanding of safety. We sought to understand the incidence and nature of patient-reported safety concerns in hospital. Methods Feedback about the experience of safety within hospital was gathered from 2471 inpatients as part of a multicentre, waitlist cluster randomised controlled trial of an intervention, undertaken within 33 wards across three English NHS Trusts, between May 2013 and September 2014. Patient volunteers, supported by researchers, developed a classification framework of patient-reported safety concerns from a random sample of 231 reports. All reports were then classified using the patient-developed categories. Following this, all patient-reported safety concerns underwent a two-stage clinical review process for identification of patient safety incidents. Results Of the 2471 inpatients recruited, 579 provided 1155 patient-reported incident reports. 14 categories were developed for classification of reports, with communication the most frequently occurring (22%), followed by staffing issues (13%) and problems with the care environment (12%). 406 of the total 1155 patient incident reports (35%) were classified by clinicians as a patient safety incident according to the standard definition. 1 in 10 patients (264 patients) identified a patient safety incident, with medication errors the most frequently reported incident. Conclusions Our findings suggest that patients can provide insight about safety that complements existing patient safety measurement, with a frequency of reported patient safety incidents that is similar to those obtained via case note review. However, patients provide a unique perspective about hospital safety which differs from and adds to current definitions of patient safety incidents

One Spin Trace Formalism for BK B_K

It has been known for some time that there are two methods to calculate $B_K$ with staggered fermions: one is the two spin trace formalism and the other is the one spin trace formalism. Until now, the two spin trace formalism has been exclusively used for weak matrix element calculations with staggered fermions. Here, the one spin trace formalism to calculate $B_K$ with staggered fermions is explained. It is shown that the one spin trace operators require additional chiral partner operators in order to keep the continuum chiral behavior. The renormalization of the one spin trace operators is described and compared with the two spin trace formalism.Comment: 47 pages, latex, 4 figures are available on reques