Combining the bulk transfer formulation and surface renewal analysis for estimating the sensible heat flux without involving the parameter KB-1

The single‐source bulk transfer formulation (based on the Monin‐Obukhov Similarity Theory, MOST) has been used to estimate the sensible heat flux, H, in the framework of remote sensing over homogeneous surfaces (HMOST). The latter involves the canopy parameter, , which is difficult to parameterize. Over short and dense grass at a site influenced by regional advection of sensible heat flux, HMOST with  = 2 (i.e., the value recommended) correlated strongly with the H measured using the Eddy Covariance, EC, method, HEC. However, it overestimated HEC by 50% under stable conditions for samples showing a local air temperature gradient larger than the measurement error, 0.4 km−1. Combining MOST and Surface Renewal analysis, three methods of estimating H that avoid dependency have been derived. These new expressions explain the variability of H versus , where is the friction velocity, is the radiometric surface temperature, and is the air temperature at height, z. At two measurement heights, the three methods performed excellently. One of the methods developed required the same readily/commonly available inputs as HMOST due to the fact that the ratio between and the ramp amplitude was found fairly constant under stable and unstable cases. Over homogeneous canopies, at a site influenced by regional advection of sensible heat flux, the methods proposed are an alternative to the traditional bulk transfer method because they are reliable, exempt of calibration against the EC method, and are comparable or identical in cost of application. It is suggested that the methodology may be useful over bare soil and sparse vegetation.This research was funded by CERESS project AGL2011–30498 (Ministerio de Economía y Competitividad of Spain, cofunded FEDER), CGL2012–37416‐C04‐01 (Ministerio de Ciencia y Innovación of Spain), and CEI Iberus, 2014 (Proyecto financiado por el Ministerio de Educación en el marco del Programa Campus de Excelencia Internacional of Spain)

Energy- and flux-budget turbulence closure model for stably stratified flows. Part II: the role of internal gravity waves

We advance our prior energy- and flux-budget turbulence closure model (Zilitinkevich et al., 2007, 2008) for the stably stratified atmospheric flows and extend it accounting for additional vertical flux of momentum and additional productions of turbulent kinetic energy, turbulent potential energy (TPE) and turbulent flux of potential temperature due to large-scale internal gravity waves (IGW). Main effects of IGW are following: the maximal value of the flux Richardson number (universal constant 0.2-0.25 in the no-IGW regime) becomes strongly variable. In the vertically homogeneous stratification, it increases with increasing wave energy and can even exceed 1. In the heterogeneous stratification, when IGW propagate towards stronger stratification, the maximal flux Richardson number decreases with increasing wave energy, reaches zero and then becomes negative. In other words, the vertical flux of potential temperature becomes counter-gradient. IGW also reduce anisotropy of turbulence and increase the share of TPE in the turbulent total energy. Depending on the direction (downward or upward), IGW either strengthen or weaken the total vertical flux of momentum. Predictions from the proposed model are consistent with available data from atmospheric and laboratory experiments, direct numerical simulations and large-eddy simulations.Comment: 37 pages, 5 figures, revised versio

Field evidence for the upwind velocity shift at the crest of low dunes

Wind topographically forced by hills and sand dunes accelerates on the upwind (stoss) slopes and reduces on the downwind (lee) slopes. This secondary wind regime, however, possesses a subtle effect, reported here for the first time from field measurements of near-surface wind velocity over a low dune: the wind velocity close to the surface reaches its maximum upwind of the crest. Our field-measured data show that this upwind phase shift of velocity with respect to topography is found to be in quantitative agreement with the prediction of hydrodynamical linear analysis for turbulent flows with first order closures. This effect, together with sand transport spatial relaxation, is at the origin of the mechanisms of dune initiation, instability and growth.Comment: 13 pages, 6 figures. Version accepted for publication in Boundary-Layer Meteorolog

Laboratory investigation of lateral dispersion within dense arrays of randomly distributed cylinders at transitional Reynolds number

Published versio

Modelling Canopy Flows over Complex Terrain

Recent studies of flow over forested hills have been motivated by a number of important applications including understanding CO22 and other gaseous fluxes over forests in complex terrain, predicting wind damage to trees, and modelling wind energy potential at forested sites. Current modelling studies have focussed almost exclusively on highly idealized, and usually fully forested, hills. Here, we present model results for a site on the Isle of Arran, Scotland with complex terrain and heterogeneous forest canopy. The model uses an explicit representation of the canopy and a 1.5-order turbulence closure for flow within and above the canopy. The validity of the closure scheme is assessed using turbulence data from a field experiment before comparing predictions of the full model with field observations. For near-neutral stability, the results compare well with the observations, showing that such a relatively simple canopy model can accurately reproduce the flow patterns observed over complex terrain and realistic, variable forest cover, while at the same time remaining computationally feasible for real case studies. The model allows closer examination of the flow separation observed over complex forested terrain. Comparisons with model simulations using a roughness length parametrization show significant differences, particularly with respect to flow separation, highlighting the need to explicitly model the forest canopy if detailed predictions of near-surface flow around forests are required

The P2 Receptor Antagonist PPADS Supports Recovery from Experimental Stroke In Vivo

BACKGROUND: After ischemia of the CNS, extracellular adenosine 5'-triphosphate (ATP) can reach high concentrations due to cell damage and subsequent increase of membrane permeability. ATP may cause cellular degeneration and death, mediated by P2X and P2Y receptors. METHODOLOGY/PRINCIPAL FINDINGS: The effects of inhibition of P2 receptors by pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) on electrophysiological, functional and morphological alterations in an ischemia model with permanent middle cerebral artery occlusion (MCAO) were investigated up to day 28. Spontaneously hypertensive rats received PPADS or vehicle intracerebroventricularly 15 minutes prior MCAO for up to 7 days. The functional recovery monitored by qEEG was improved by PPADS indicated by an accelerated recovery of ischemia-induced qEEG changes in the delta and alpha frequency bands along with a faster and sustained recovery of motor impairments. Whereas the functional improvements by PPADS were persistent at day 28, the infarct volume measured by magnetic resonance imaging and the amount of TUNEL-positive cells were significantly reduced by PPADS only until day 7. Further, by immunohistochemistry and confocal laser scanning microscopy, we identified both neurons and astrocytes as TUNEL-positive after MCAO. CONCLUSION: The persistent beneficial effect of PPADS on the functional parameters without differences in the late (day 28) infarct size and apoptosis suggests that the early inhibition of P2 receptors might be favourable for the maintenance or early reconstruction of neuronal connectivity in the periinfarct area after ischemic incidents

Why don't hospital staff activate the rapid response system (RRS)? How frequently is it needed and can the process be improved?

Abstract Background The rapid response system (RRS) is a process of accessing help for health professionals when a patient under their care becomes severely ill. Recent studies and meta-analyses show a reduction in cardiac arrests by a one-third in hospitals that have introduced a rapid response team, although the effect on overall hospital mortality is less clear. It has been suggested that the difficulty in establishing the benefit of the RRS has been due to implementation difficulties and a reluctance of clinical staff to call for additional help. This assertion is supported by the observation that patients continue to have poor outcomes in our institution despite an established RRS being available. In many of these cases, the patient is often unstable for many hours or days without help being sought. These poor outcomes are often discovered in an ad hoc fashion, and the real numbers of patients who may benefit from the RRS is currently unknown. This study has been designed to answer three key questions to improve the RRS: estimate the scope of the problem in terms of numbers of patients requiring activation of the RRS; determine cognitive and socio-cultural barriers to calling the Rapid Response Team; and design and implement solutions to address the effectiveness of the RRS. Methods The extent of the problem will be addressed by establishing the incidence of patients who meet abnormal physiological criteria, as determined from a point prevalence investigation conducted across four hospitals. Follow-up review will determine if these patients subsequently require intensive care unit or critical care intervention. This study will be grounded in both cognitive and socio-cultural theoretical frameworks. The cognitive model of situation awareness will be used to determine psychological barriers to RRS activation, and socio-cultural models of interprofessional practice will be triangulated to inform further investigation. A multi-modal approach will be taken using reviews of clinical notes, structured interviews, and focus groups. Interventions will be designed using a human factors analysis approach. Ongoing surveillance of adverse outcomes and surveys of the safety climate in the clinical areas piloting the interventions will occur before and after implementation

Effects of mental practice embedded in daily therapy compared to therapy as usual in adult stroke patients in Dutch nursing homes: design of a randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>Mental practice as an additional cognitive therapy is getting increased attention in stroke rehabilitation. A systematic review shows some evidence that several techniques in which movements are rehearsed mentally might be effective but not enough to be certain. This trial investigates whether mental practice can contribute to a quicker and/or better recovery of stroke in two Dutch nursing homes. The objective is to investigate the therapeutic potential of mental practice embedded in daily therapy to improve individually chosen daily activities of adult stroke patients compared to therapy as usual. In addition, we will investigate prognostic variables and feasibility (process evaluation).</p> <p>Methods</p> <p>A randomised, controlled, observer masked prospective trial will be conducted with adult stroke patients in the (sub)acute phase of stroke recovery. Over a six weeks intervention period the control group will receive multi professional therapy as usual. Patients in the experimental group will be instructed how to perform mental practice, and will receive care as usual in which mental practice is embedded in physical, occupation and speech therapy sessions. Outcome will be assessed at six weeks and six months. The primary outcome measure is the patient-perceived effect on performance of daily activities as assessed by an 11-point Likert Scale. Secondary outcomes are: Motricity Index, Nine Hole Peg Test, Barthel Index, Timed up and Go, 10 metres walking test, Rivermead Mobility Index. A sample size of the patients group and all therapists will be interviewed on their opinion of the experimental program to assess feasibility. All patients are asked to keep a log to determine unguided training intensity.</p> <p>Discussion</p> <p>Advantages and disadvantages of several aspects of the chosen design are discussed.</p> <p>Trial registration</p> <p>ISRCTN27582267</p

Electrospun Polyurethane Fibers for Absorption of Volatile Organic Compounds from Air

Electrospun polyurethane fibers for removal of volatile organic compounds (VOC) from air with rapid VOC absorption and desorption have been developed. Polyurethanes based on 4,4-methylenebis(phenylisocyanate) (MDI) and aliphatic isophorone diisocyanate as the hard segments and butanediol and tetramethylene glycol as the soft segments were electrospun from their solutions in N,N-dimethylformamide to form micrometer-sized fibers. Although activated carbon possessed a many-fold higher surface area than the polyurethane fiber meshes, the sorption capacity of the polyurethane fibers was found to be similar to that of activated carbon specifically designed for vapor adsorption. Furthermore, in contrast to VOC sorption on activated carbon, where complete regeneration of the adsorbent was not possible, the polyurethane fibers demonstrated a completely reversible absorption and desorption, with desorption obtained by a simple purging with nitrogen at room temperature. The fibers possessed a high affinity toward toluene and chloroform, but aliphatic hexane lacked the necessary strong attractive interactions with the polyurethane chains and therefore was less strongly absorbed. The selectivity of the polyurethane fibers toward different vapors, along with the ease of regeneration, makes them attractive materials for VOC filtration.Boeing CompanyNetherlands Organisation for Scientific Research (NWO) (Talent Scholarship

A social network approach to examine K-12 educational leaders’ influence on information diffusion on Twitter

This study investigated the relationship between the leader’s gender, leadership position, Twitter use, and influence on information diffusion in the communication network on Twitter. We collected the 30,200 latest tweets of 151 active Twitter users who held educational leadership positions. Results of social network analysis and multiple regression analyses suggest a gender inequality in the leader’s influence on information diffusion in the network. Findings also indicate no significant relationship between leadership position (district vs. building) and a leader\u27s influence in the network. Moreover, Twitter following was positively associated with the leader’s influence in the network, whereas the number of followers, weekly tweets, and the time of Twitter account creation did not predict the leader’s influence. Practical implications on how leaders use Twitter to disseminate information are discussed