Compatible finite element methods for numerical weather prediction

This article takes the form of a tutorial on the use of a particular class of mixed finite element methods, which can be thought of as the finite element extension of the C-grid staggered finite difference method. The class is often referred to as compatible finite elements, mimetic finite elements, discrete differential forms or finite element exterior calculus. We provide an elementary introduction in the case of the one-dimensional wave equation, before summarising recent results in applications to the rotating shallow water equations on the sphere, before taking an outlook towards applications in three-dimensional compressible dynamical cores.Comment: To appear in ECMWF Seminar proceedings 201

Giant Electron-hole Charging Energy Asymmetry in Ultra-short Carbon Nanotubes

Making full usage of bipolar transport in single-wall carbon nanotube (SWCNT) transistors could permit the development of two-in-one quantum devices with ultra-short channels. We report on clean $\sim$10 to 100 nm long suspended SWCNT transistors which display a large electron-hole transport asymmetry. The devices consist of naked SWCNT channels contacted with sections of SWCNT-under-annealed-gold. The annealed gold acts as an n-doping top gate which creates nm-sharp barriers at the junctions between the contacts and naked channel. These tunnel barriers define a single quantum dot (QD) whose charging energies to add an electron or a hole are vastly different ($e-h$ charging energy asymmetry). We parameterize the $e-h$ transport asymmetry by the ratio of the hole and electron charging energies $\eta_{e-h}$. We show that this asymmetry is maximized for short channels and small band gap SWCNTs. In a small band gap SWCNT device, we demonstrate the fabrication of a two-in-one quantum device acting as a QD for holes, and a much longer quantum bus for electrons. In a 14 nm long channel, $\eta_{e-h}$ reaches up to 2.6 for a device with a band gap of 270 meV. This strong $e-h$ transport asymmetry survives even at room temperature

The experiences of individuals with cervical spinal cord injury and their family during post-injury care in non-specialised and specialised units in UK

BACKGROUND: Individuals with acute cervical spinal cord injury require specialised interventions to ensure optimal clinical outcomes especially for respiratory, swallowing and communication impairments. This study explores the experiences of post-injury care for individuals with cervical spinal cord injury and their family members during admissions in specialised and non-specialised units in the United Kingdom. METHODS: Semi-structured interviews were undertaken with individuals with a cervical spinal cord injury and their family member, focussing on the experience of care across units. Eight people with spinal cord injury levels from C2 to C6, were interviewed in their current care settings. Six participants had family members present to support them. Interviews were audio-recorded and transcribed with data inputted into NVivo for thematic analysis. RESULTS: The study identified six themes from the participant interviews that highlighted different experiences of care in non-specialised and specialised settings. A number of these were related to challenges with the system, whilst others were about the personal journey of recovery. The themes were titled as: adjustment, transitions, "the golden opportunity", "when you can't eat", communication, and "in the hands of the nurses and doctors". CONCLUSIONS: Whilst participants reported being well cared for in non-specialised units, they felt that they did not receive specialist care and this delayed their rehabilitation. Participants were dependent on healthcare professionals for information and care and at times lost hope for recovery. Staff in non-specialised units require training and guidance to help provide support for those with dysphagia and communication difficulties, as well as reassurance to patients and families whilst they wait for transfer to specialised units

Development of a swallowing risk screening tool and best practice recommendations for the management of oropharyngeal dysphagia following acute cervical spinal cord injury: an international multi-professional Delphi consensus

Purpose: International multi-professional expert consensus was sought to develop best practice recommendations for clinical management of patients following cervical spinal cord injury with oropharyngeal dysphagia and associated complications. Additionally, risk factors for dysphagia were identified to support the development of a screening tool. // Materials and Methods: A two-round Delphi study was undertaken with a 27-member panel of expert professionals in cervical spinal cord injury and complex dysphagia. They rated 85 statements across seven topic areas in round one, using a five-point Likert scale with a consensus set at 70%. Statements not achieving consensus were revised for the second round. Comparative group and individual feedback were provided at the end of each round. // Results: Consensus was achieved for 50 (59%) statements in round one and a further 12 (48%) statements in round two. Recommendations for best practice were agreed for management of swallowing, respiratory function, communication, nutrition and oral care. Twelve risk factors for dysphagia were identified for components of a screening tool. // Conclusions: Best practice recommendations support wider clinical management to prevent complications and direct specialist care. Screening for risk factors allows early dysphagia identification with the potential to improve clinical outcomes. Further evaluation of the impact of these recommendations is needed