Northumbria University

About: Northumbria University is a education organization based out in Newcastle upon Tyne, United Kingdom. It is known for research contribution in the topics: Context (language use) & Population. The organization has 5624 authors who have published 17423 publications receiving 381949 citations. The organization is also known as: University of Northumbria at Newcastle.

Apparent contact angle and contact angle hysteresis on liquid infused surfaces

Abstract: We theoretically investigate the apparent contact angle and contact angle hysteresis of a droplet placed on a liquid infused surface. We show that the apparent contact angle is not uniquely defined by material parameters, but also has a dependence on the relative size between the droplet and its surrounding wetting ridge formed by the infusing liquid. We derive a closed form expression for the contact angle in the limit of vanishing wetting ridge, and compute the correction for small but finite ridge, which corresponds to an effective line tension term. We also predict contact angle hysteresis on liquid infused surfaces generated by the pinning of the contact lines by the surface corrugations. Our analytical expressions for both the apparent contact angle and contact angle hysteresis can be interpreted as ‘weighted sums’ between the contact angles of the infusing liquid relative to the droplet and surrounding gas phases, where the weighting coefficients are given by ratios of the fluid surface tensions.

Systematic review of acute physically active learning and classroom movement breaks on children's physical activity, cognition, academic performance and classroom behaviour: understanding critical design features.

Abstract: Objective To examine the impact of acute classroom movement break (CMB) and physically active learning (PAL) interventions on physical activity (PA), cognition, academic performance and classroom behaviour. Design Systematic review. Data sources PubMed, EBSCO, Academic Search Complete, Education Resources Information Center, PsycINFO, SPORTDiscus, SCOPUS and Web of Science. Eligibility criteria for selecting studies Studies investigating school-based acute bouts of CMB or PAL on (PA), cognition, academic performance and classroom behaviour. The Downs and Black checklist assessed risk of bias. Results Ten PAL and eight CMB studies were identified from 2929 potentially relevant articles. Risk of bias scores ranged from 33% to 64.3%. Variation in study designs drove specific, but differing, outcomes. Three studies assessed PA using objective measures. Interventions replaced sedentary time with either light PA or moderate-to-vigorous PA dependent on design characteristics (mode, duration and intensity). Only one study factored individual PA outcomes into analyses. Classroom behaviour improved after longer moderate-to-vigorous (>10 min), or shorter more intense (5 min), CMB/PAL bouts (9 out of 11 interventions). There was no support for enhanced cognition or academic performance due to limited repeated studies. Conclusion Low-to-medium quality designs predominate in investigations of the acute impacts of CMB and PAL on PA, cognition, academic performance and classroom behaviour. Variable quality in experimental designs, outcome measures and intervention characteristics impact outcomes making conclusions problematic. CMB and PAL increased PA and enhanced time on task. To improve confidence in study outcomes, future investigations should combine examples of good practice observed in current studies. PROSPERO registration number CRD42017070981.

Channel Characteristics of Visible Light Communications Within Dynamic Indoor Environment

Abstract: Visible light communications (VLC) is a new emerging technology, which provides both data transmission and illumination by utilizing the visible range (370-780 nm) of the electromagnetic spectrum. In order to maximize the available data rate and enhance the users mobility within an indoor environment, it is essential to characterize the communication channel. In this paper, we present both analytical and experimental results for a VLC system affected by movement of people for different indoor conditions (i.e., furnished office room, empty hall, and corridor). VLC systems utilize multiple light-emitting diodes mounted in the ceiling and the configuration is based on the nondirected line of sight. We consider random movement of people within the room, focusing on the impacts of shadowing and blocking on mobility and link system performance by investigating changes in the channel characteristics using the cumulative distribution function of the received power distribution and the delay profile. We demonstrate the behaviour of communication channels for different scenarios from corridor, the most robust against people movement induced fading, to the office rooms and halls, the most vulnerable to the received power fluctuation.