996 resultados para effective microorganisms


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Accurate fine-structure atomic data for the Fe-peak elements are essential for interpreting astronomical spectra. There is a severe paucity of data available for Sc II, highlighted by the fact that no collision strengths are readily available for this ion. We present electron-impact excitation collision strengths and Maxwellian averaged effective collision strengths for Sc II. The collision strengths were calculated for all 3916 transitions amongst 89 jj levels (arising from the 3d4s, 3d2, 4s2, 3d4p, 4s4p, 3d5s, 3d4d, 3d5p, 4p2 and 3d4f configurations), resulting in a 944 coupled channel problem. The R-matrix package RMATRXII was utilized, along with the transformation code FINE and the external region code PSTGF, to calculate the collision strengths for a range of incident electron energies in the 0 to 8.3 Rydberg region. Maxwellian averaged effective collision strengths were then produced for 27 temperatures lying within the astrophysically significant range of 30 to 105 K.
The collision strengths and effective collision strengths were produced for two different target models. The purpose was to systematically examine the effect of including open 3p correlation terms into the configuration interaction expansion for the wavefunction. The first model consisted of all 36 CI terms that could be generated with the 3p core closed. The second model incorporated an additional six configurations which allowed for single-electron excitations from within the 3p core. Comparisons are made between the two models and the results of Bautista et al., obtained by private communication. It is concluded that the first model produced the most reliable set of collision and effective collision strengths for use in astrophysical and plasma applications.

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Article 260(2) TFEU (ex 228(2) EC) enables the European Court of Justice to enforce compliance with its judgements. This article analyses its use in doing so and questions whether it could be applied more effectively. It commences by highlighting the principally economic and environmental context of the case-law, and by examining the initiatives taken to tackle delays in bringing these cases before the Court. The article then critically evaluates the effectiveness of the financial sanctions available to the Court. In doing so, it aims to fill a gap in present research by looking beyond the procedural measures through which the Court and the Commission operate to examine the practical impact of Article 260(2) itself.

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A survey of the utilization by environmental micro-organisms of a range of compounds containing the carbon-phosphorus (C-P) bond was carried out. Elective culture studies indicated that 15 of 19 alkylphosphonates tested served only as a sole source of phosphorus for microbial growth. Their metabolism did not lead to the extracellular release of inorganic phosphate. However, four organophosphonates - phosphonoacetate, phosphonoalanine, 2-aminoethylphosphonate and phosphonomycin - supported microbial growth when supplied as either a phosphorus source or as a carbon and energy source, with near-quantitative inorganic phosphate release. Four of five amino alkylphosphonates tested were also utilized as a nitrogen source in the presence of 1 mmol l(-1) inorganic phosphate. In a subsequent screening programme, 99% of bacterial isolates tested were able to utilize 2-aminoethylphosphonate as a sole phosphorus source, 61% as a nitrogen source, 10% as a source of nitrogen and phosphorus, and 2% as a source of carbon, nitrogen and phosphorus; 2% of isolates used phosphonoalanine as a nitrogen source. These results suggest that the uptake and metabolism of organophosphonates by bacteria is less 'tightly' regulated by phosphorus starvation than has previously been supposed.

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OBJECTIVE: There is a widely recognised need to develop effective Alzheimer's disease (AD) biomarkers to aid the development of disease-modifying treatments, to facilitate early diagnosis and to improve clinical care. This overview aims to summarise the utility of key neuroimaging and cerebrospinal fluid (CSF) biomarkers for AD, before focusing on the latest efforts to identify informative blood biomarkers. DESIGN: A literature search was performed using PubMed up to September 2011 for reviews and primary research studies of neuroimaging (magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography and amyloid imaging), CSF and blood-based (plasma, serum and platelet) biomarkers in AD and mild cognitive impairment. Citations within individual articles were examined to identify additional studies relevant to this review. RESULTS: Evidence of AD biomarker potential was available for imaging techniques reflecting amyloid burden and neurodegeneration. Several CSF measures are promising, including 42 amino acid ß-amyloid peptide (Aß(42) ); total tau (T-tau) protein, reflecting axonal damage; and phosphorylated tau (P-tau), reflecting neurofibrillary tangle pathology. Studies of plasma Aß have produced inferior diagnostic discrimination. Alternative plasma and platelet measures are described, which represent potential avenues for future research. CONCLUSIONS: Several imaging and CSF markers demonstrate utility in predicting AD progression and determining aetiology. These require standardisation before forming core elements of diagnostic criteria. The enormous potential available for identifying a minimally-invasive, easily-accessible blood measure as an effective AD biomarker currently remains unfulfilled. Copyright © 2012 John Wiley & Sons, Ltd.

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Rhizosphere microorganisms play an important role in soil carbon flow, through turnover of root exudates, but there is little information on which organisms are actively involved or on the influence of environmental conditions on active communities. In this study, a (CO2)-C-13 pulse labelling field experiment was performed in an upland grassland soil, followed by RNA-stable isotope probing (SIP) analysis, to determine the effect of liming on the structure of the rhizosphere microbial community metabolizing root exudates. The lower limit of detection for SIP was determined in soil samples inoculated with a range of concentrations of C-13-labelled Pseudomonas fluorescens and was found to lie between 10(5) and 10(6) cells per gram of soil. The technique was capable of detecting microbial communities actively assimilating root exudates derived from recent photo-assimilate in the field. Denaturing gradient gel electrophoresis (DGGE) profiles of bacteria, archaea and fungi derived from fractions obtained from caesium trifluoroacetate (CsTFA) density gradient ultracentrifugation indicated that active communities in limed soils were more complex than those in unlimed soils and were more active in utilization of recently exuded C-13 compounds. In limed soils, the majority of the community detected by standard RNA-DGGE analysis appeared to be utilizing root exudates. In unlimed soils, DGGE profiles from C-12 and C-13 RNA fractions differed, suggesting that a proportion of the active community was utilizing other sources of organic carbon. These differences may reflect differences in the amount of root exudation under the different conditions.

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The overall aim of this research is to identify and catalogue the numerous managerial strategies for effective management of health and safety on a confined, urban, construction site. A mixed methods methodology was adopted using interviews and focus group discussions on three selected case studies of confined construction sites. In addition to these, a questionnaire survey was used based on the findings from the interviews and the focus group discussions. The top five key strategies include (1) Employ safe system of work plans to mitigate personnel health and safety issues; (2) Inform personnel, before starting on-site, of the potential issues using site inductions; (3) Effective communication among site personnel; (4) Draft and implement an effective design site layout prior to starting on-site; and (5) Use of banksman (traffic co-ordinator) to segregate personnel from vehicular traffic. The construction sector is one of the leading industries in accident causation and with the continued development and regeneration of our urban centres, confined site construction is quickly becoming the norm - an environment which only fuels accident creation within the construction sector. This research aids on-site management that requires direction and assistance in the identification and implementation of key strategies for the management of health and safety, particularly in confined construction site environments.