2,814 research outputs found
Acute pulmonary pathology and sudden death in rats following the intravenous administration of the plasticizer, DI (2-ethylhexyl) phthalate, solubilized with Tween surfactants
Intravenous administration of 200-300 mg/kg of di(2-ethylhexyl)phthalate (DEHP) solubilized in aqueous solutions of several Tween surfactants caused respiratory distress in rats. There was a dose-dependent lethality with death generally occurring within 90 minutes after injection. The lungs from DEHP:Tween treated animals were enlarged, generally darkened, and in some cases showed hemorrhagic congestion. Neither the overt symptoms nor the morphologic alterations resulting from DEHP:Tween administration could be reproduced by intravenous administration of aqueous Tween solutions alone. The absence of pulmonary abnormalities following the intravenous administration of DEHP as an aqueous emulsion given either alone or even as soon as 2 minutes after pretreatment with Tween 80, suggests that the specific in vivo interaction between DEHP and Tween surfactants depends on the prior formation of water-soluble micelles of DEHP
Modularised process-based modelling of phosphorus loss at farm and catchment scale
In recent years, a co-ordinated programme of data collection has resulted in the collation of sub-hourly time-series of hydrological, sediment and phosphorus loss data, together with soil analysis, cropping and management information for two small (< 200 ha) headwater agricultural catchments in the UK Midlands (Rosemaund, Herefordshire and Cliftonthorpe, Leicestershire). These data sets have allowed the dynamics of phosphorus loss to be characterised and the importance of both storm runoff and drainflow to be identified, together with incidental losses following manure and fertiliser additions in contributing to total annual loss. A modularised process-based model has been developed to represent current understanding of the dynamics of phosphorus loss. Modules describing runoff and sediment generation and associated phosphorus adsorption/desorption dynamics are described and tested. In the model, the effect of a growing crop on sediment detachment processes is represented and the stability of topsoil is considered so that, overall, the model is responsive to farm management factors. Importantly, using data sets available from national-scale survey programmes to estimate model parameters, a transferable approach is presented, requiring only sub-hourly rainfall data and field-specific landcover information for application of the model to new sites. Results from application of the model to the hydrological year 1998â99 are presented. Assessment of performance, which suggests that the timing of simulated responses is acceptable, has focused attention on quantifying landscape and in-stream retention and remobilisation processes.</b></p> <p style='line-height: 20px;'><b>Keywords: </b>phosphorus, erosion, process-based modelling, agricultur
The Role of Relapse Prevention and Goal Setting in Training Transfer Enhancement
This article reviews the effect of two post-training transfer interventions (relapse prevention [RP] and goal setting [GS]) on traineesâ ability to apply skills gained in a training context to the workplace. Through a review of post-training transfer interventions literature, the article identifies a number of key issues that remain unresolved or underexplored, for example, the inconsistent results on the impact of RP on transfer of training, the lack of agreement on which GS types are more efficient to improve transfer performance, the lack of clarity about the distinction between RP and GS, and the underlying process through which these two post-training transfer interventions influence transfer of training. We offer some recommendations to overcome these problems and also provide guidance for future research on transfer of training
Evaluation and interpretation of regional and site-specific hydrochemical data bases for water quality assessment
International audienceThe spatial distribution of stream water composition, as determined by the Geochemical Baseline Survey of the Environment (G-BASE) conducted by the British Geological Survey (BGS) can be successfully related under baseflow conditions to bedrock geochemistry. Further consideration of results in conjunction with site-specific monitoring data enables factors controlling both spatial and temporal variability in major element composition to be highlighted and allows the value of the survey to be enhanced. Hence, chemical data (i) from streams located on Lower Silurian (Llandovery) bedrock at 1 km2 resolution collected as part of the G-BASE survey of Wales and the West Midlands and (ii) from catchment monitoring studies located in upland mid-Wales (conducted by Institute of Terrestrial Ecology), have been considered together as an example. Classification of the spatial survey data set in terms of potentially controlling factors was carried out so as to illustrate the level of explanation they could give in terms of observed spatial chemical variability. It was therefore hypothesised that on a geological lithostratigraphic series of limited geochemical contrast, altitude and land-use factors provide better explanation of this variability than others such as lithology at sampling site and stream order. At an individual site, temporal variability was also found to be of considerable significance and, at a monthly time-step, is explicable in terms of factors such as antecedent conditions and seasonality. Data suggest that the degree of this variability may show some relationship with stream order and land-use. Monitoring data from the region also reveal that relationships between stream chemistry and land-use may prove to be strong not only at base flow but also in storm flow conditions. In a wider context, predictions of the sensitivity of stream water to acidification based on classifications of soil and geology are successful on a regional scale. However, the study undertaken here has shown that use of such classification schemes on a catchment scale results in considerable uncertainty associated with prediction. Uncertainties are due to the large degree of variability in stream chemistry encountered both spatially within geological units and temporally at individual sampling sites
Intense summer floods may induce prolonged increases in benthic respiration rates of more than one year leading to low river dissolved oxygen
The supply of readily-degradable organic matter to river systems can cause stress to dissolved oxygen (DO) in slow-flowing waterbodies. To explore this threat, a multi-disciplinary study of the River Thames (UK) was undertaken over a six-year period (2009â14). Using a combination of observations at various time resolutions (monthly to hourly), physics-based river network water quality modelling (QUESTOR) and an analytical tool to estimate metabolic regime (Delta method), a decrease in 10th percentile DO concentration (10-DO, indicative of summer low levels) was identified during the study period. The assessment tools suggested this decrease in 10-DO was due to an increase in benthic heterotrophic respiration. Hydrological and dissolved organic carbon (DOC) data showed that the shift in 10-DO could be attributed to summer flooding in 2012 and consequent connection of pathways flushing degradable organic matter into the river. Comparing 2009â10 and 2013â14 periods, 10-DO decreased by 7.0% at the basin outlet (Windsor) whilst median DOC concentrations in a survey of upstream waterbodies increased by 5.5â48.1%. In this context, an anomalous opposing trend in 10-DO at one site on the river was also identified and discussed. Currently, a lack of process understanding of spatio-temporal variability in benthic respiration rates is hampering model predictions of river DO. The results presented here show how climatic-driven variation and urbanisation induce persistent medium-term changes in the vulnerability of water quality to multiple stressors across complex catchment systems
The precautions of clinical waste: disposable medical sharps in the United Kingdom
This article deals with recent changes in UK guidance on clinical waste, in particular a shift to disposable, single-use instruments and sharps. I use interviews conducted with nurses from a GP practice and two clinical waste managers at alternative treatment and incineration sites as a springboard for reflection on the relationship between the legislation on clinical waste management and its implementation. Scrutinizing the UK guidance, European legislation and World Health Organization principles, I draw out intervieweesâ concerns that the changed practices lead to an expansion of the hazardous waste category, with an increased volume going to incineration. This raises questions regarding the regulationsâ environmental and health effects, and regarding the precautionary approach embedded in the regulations. Tracing the diverse reverberations of the term âwasteâ in different points along the journeys made by sharps in particular, and locating these questions in relation to existing literature on waste, I emphasize that public health rationales for the new practices are not made clear in the guidance. I suggest that this relative silence on the subject conceals both the uncertainties regarding the necessity for these means of managing the risks of infectious waste, and the tensions between policies of precautionary public health and environmental sustainability
Coverage-dependent adsorption sites in the K/Ru(0001) system: a low-energy electron-diffraction analysis
The two ordered phases p(2 Ă 2) at a coverage Ξ = 0.25 and (â3 Ă â3)R30° at Ξ = 0.33 of potassium adsorbed on Ru(0001) were analyzed by use of low-energy electron-diffraction (LEED). In the (â3 Ă â3)R30° phase, the K atoms occupy threefold hcp sites, while in the p(2 Ă 2) phase the fcc site is favoured. In both phases, the K hard-sphere radii are nearly the same and close to the covalent Pauling radius
Progressive genetic aberrations detected by comparative genomic hybridization in squamous cell cervical cancer
Genetic changes orchestrated by human papillomaviruses are the most important known factors in carcinogenesis of the uterine cervix. However, it is clear that additional genetic events are necessary for tumour progression. We have used comparative genomic hybridization to document non-random chromosomal gains and losses within a subset of 37 cervical carcinomas matched for clinical stage Ib, but with different lymph node status. There were significantly more chromosomal changes in the primary tumours when the lymph nodes were positive for metastases. The most frequent copy number alterations were loss of 3p, 11q, 6q and 10q and gain of 3q. The smallest areas of loss and gain on chromosome 3 were 3p14â22 and 3q24â26. The study identifies progressive DNA copy number changes associated with early-stage invasive cervical cancers with and without lymph node metastases, a factor of potential prognostic and therapeutic value. © 2000 Cancer Research Campaign http://www.bjcancer.co
Iron biogeochemistry across marine systems progress from the past decade
Based on an international workshop (Gothenburg, 14â16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas
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