1,540 research outputs found
Prayer and psychological health: a study among sixth-form pupils attending Catholic and Protestant schools in Northern Ireland
Eysenck's dimensional model of personality includes two indicators of psychological health, defined as neuroticism and psychoticism. In order to examine the association between psychological health and prayer, two samples of sixth-form pupils in Northern Ireland (16- to 18-year-olds) attending Catholic (N = 1246) and Protestant (N = 1060) schools completed the abbreviated Revised Eysenck Personality Questionnaire alongside a simple measure of prayer frequency. The data demonstrated a positive association between prayer frequency and better levels of psychological health as assessed by Eysenck's notion of psychoticism. Among pupils attending both Catholic and Protestant schools, higher levels of prayer were associated with lower psychoticism scores. Among pupils attending Catholic schools, however, higher levels of prayer were also associated with higher neuroticism scores
Sewage disposal in the Musi-River, India: water quality remediation through irrigation infrastructure
The disposal of untreated urban sewage in to open water bodies is common in most developing countries. This poses potential negative consequences to public health and agricultural sustainability. Hyderabad, one of India's largest cities, disposes large amounts of its wastewater untreated into the Musi River, from where it is used, with the aid of irrigation weirs, for agricultural production. This paper presents a 14 month (December 2003 - January 2005) water quality survey which aimed to quantify spatial and temporal changes in key water quality parameters along a 40 km stretch of the Musi River. The survey found that river water quality improved dramatically with distance from the city; from untreated sewage in the city to irrigation water safe for use in agriculture 40 km downstream of the city. This improvement was contributed to by different treatment processes caused or aided by the irrigation weirs placed on the river. © 2009 Springer Science+Business Media B.V
Hydrodynamic independence and passive control application of twist and flapwise deformations of tidal turbine blades
The load-induced deformations experienced by axial-flow rotor blades can result in significant hydrodynamic impacts on rotor operation. These changes in hydrodynamics are dominated by the flapwise and twist deformation components, affecting blade loading and performance. This work uses blade-resolved computational fluid dynamics simulations to explore the hydrodynamic interactions of coupled flapwise and twist deformations, and their potential for use in passive control strategies. The rotor blades were simulated under parametrically prescribed flapwise-only, twist-only and coupled flapwise–twist deformations. The results show that the hydrodynamic effects are adequately described by blade-element theory for twist deformations regardless of the presence of flapwise deformations, whereas flapwise deformations induce changes in the local lift and drag coefficients that are independent of twist. For moderate blade deflections, the hydrodynamic changes generated by the two deformation components can be approximated to be independent from each other. The observed hydrodynamic independence between the two deformation components is used to explore passive deformation strategies for a tidal rotor. By extrapolating an existing dataset containing CFD simulations of twist-only and flapwise-only deformation cases at different tip-speed ratios, control paths are designed within a tip-speed ratio, flapwise and twist deformation parameter space. These control paths demonstrate passive control strategies as a potential alternative to active pitch control on tidal turbines, showing similar performance and maximum loading, compared with an active pitch strategy, over a full tidal cycle. In particular, it is shown that flapwise deformations have an important role in power capping above rated flow speed
A numerical study on the hydrodynamics of a floating tidal rotor under the combined effects of currents and waves
This work examines the hydrodynamics of a 20 m diameter axial-flow tidal rotor supported by a catamaran-style floating platform. Using a time-domain seakeeping model of the float, coupled with a dynamic model of the rotor based on blade-element momentum theory, the floating tidal turbine was analysed under the combined effects of following waves and currents. The rotor loads were analysed in scenarios with and without platform motions, starting from equivalent initial conditions. While the results show that mean power and thrust are not significantly affected, thrust and power fluctuations are substantial for the rotor under waves with and without platform motions. When platform motions were considered, amplification and reduction of load fluctuations were observed at different wave periods. These effects are associated with the phase interactions between waves and platform motion response. The reductions in thrust and power fluctuations at certain ranges of wave periods suggest that platform motions do not necessarily have an adverse impact on the operation of floating tidal rotors and could potentially be exploited to reduce fatigue damage and improve the quality of power delivery. The amplification of transient loads, on the contrary, suggests that consideration is required when designing floating systems to avoid potentially damaging effects
Dynamic Mode Decomposition of merging wind turbine wakes
The design and operation of wind farms is significantly affected by the impact that upstream turbine wakes have on the power production and fatigue loading of subsequent turbines; often called the wake effect. In this work, two types of flows are considered: the wake of a single turbine with a laminar inflow and the combined wake of two turbines operating in-line where the upstream wake results in an unsteady inflow for the downstream turbine. Those two scenarios are simulated using large eddy simulation (LES) and the actuator line method (ALM). The spatio-temporal velocity fields are analyzed by means of high order dynamic mode decomposition (HODMD), a well established variant of the DMD. The results show that most of the higher frequencies characterizing the laminar case are instead dominated by the lower frequency modes in the combined wake. This suggests that structures emerging from the blade rotations in a wind turbine wake may be less significant for describing the wake dynamics when the rotor is operating in the unsteady wake of an upstream rotor
Near-field microwave techniques for micro – and nano - scale characterization in materials science
In this paper, the basic principles of Near-Field Microscopy will be reviewed with focus on the micro-
and nano-scale resolution configurations for material science measurements. Results on doping profile, dielectric
and magnetic properties will be presented, with details on the calibration protocols needed for quantitative estimation
of the dielectric constant and of the permeability
The Royal College of Ophthalmologists' National Ophthalmology Database study of cataract surgery: Report 7, immediate sequential bilateral cataract surgery in the UK: Current practice and patient selection.
BACKGROUND: Cataract extraction is the most frequently performed surgical intervention in the world and demand is rising due to an ageing demography. One option to address this challenge is to offer selected patients immediate sequential bilateral cataract surgery (ISBCS). This study aims to investigate patient and operative characteristics for ISBCS and delayed bilateral cataract surgery (DSCS) in the UK. METHODS: Data were analysed from the Royal College of Ophthalmologists' National Ophthalmology Database Audit (NOD) of cataract surgery. Eligible patients were those undergoing bilateral cataract extraction from centres with a record of at least one ISBCS operation between 01/04/2010 and 31/08/2018. Variable frequency comparison was undertaken with chi-square tests. RESULTS: During the study period, 1073 patients had ISBCS and 248,341 DSCS from 73 centres. A higher proportion of ISBCS patients were unable to lie flat (11.3% vs. 1.8%; p < 0.001), unable to cooperate (9.7% vs. 2.7%; p < 0.001); underwent general anaesthesia (58.7% vs. 6.6% (p < 0.001)); had brunescent/white/mature cataracts (odds ratio (OR) 5.118); no fundal view/vitreous opacities (OR 8.381); had worse pre-operative acuity 0.60 LogMAR ISBCS vs. 0.50 (first) and 0.40 (second eye) DSCS and were younger (mean ages, 71.5 vs. 75.6 years; p < 0.001). Posterior capsular rupture (PCR) rates adjusted for case complexity were comparable (0.98% ISBCS and 0.78% DSCS). CONCLUSIONS: ISBCS was performed on younger patients, with difficulty cooperating and lying flat, worse pre-operative vision, higher rates of known PCR risk factors and more frequent use of general anaesthesia than DSCS in centres recorded on NOD
Passive water control at the surface of a superhydrophobic lichen
Some lichens have a super-hydrophobic upper surface, which repels water drops, keeping the surface dry but probably preventing water uptake. Spore ejection requires water and is most efficient just after rainfall. This study was carried out to investigate how super-hydrophobic lichens manage water uptake and repellence at their fruiting bodies, or podetia. Drops of water were placed onto separate podetia of Cladonia chlorophaea and observed using optical microscopy and cryo-scanning-electron microscopy (cryo-SEM) techniques to determine the structure of podetia and to visualise their interaction with water droplets. SEM and optical microscopy studies revealed that the surface of the podetia was constructed in a three-level structural hierarchy. By cryo-SEM of water-glycerol droplets placed on the upper part of the podetium, pinning of the droplet to specific, hydrophilic spots (pycnidia/apothecia) was observed. The results suggest a mechanism for water uptake, which is highly sophisticated, using surface wettability to generate a passive response to different types of precipitation in a manner similar to the Namib Desert beetle. This mechanism is likely to be found in other organisms as it offers passive but selective water control
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