11 resultados para 1040
Resumo:
The success of sequestration-based remediation strategies will depend on detailed information, including the predominant U species present as sources before biostimulation and the products produced during and after in situ biostimulation. We used X-ray absorption spectroscopy to determine the valence state and chemical speciation of U in sediment samples collected at a variety of depths through the contaminant plume at the Field Research Center at Oak Ridge, TN, before and after approximately 400 days of in situ biostimulation, as well as in duplicate bioreduced sediments after 363 days of resting conditions. The results indicate that U(VI) in subsurface sediments was partially reduced to 10–40% U(IV) during biostimulation. After biostimulation, U was no longer bound to carbon ligands and was adsorbed to Fe/Mn minerals. Reduction of U(VI) to U(IV) continued in sediment samples stored under anaerobic condition at <4 °C for 12 months, with the fraction of U(IV) in sediments more than doubling and U concentrations in the aqueous phase decreasing from 0.5-0.74 to <0.1 µM. A shift of uranyl species from uranyl bound to phosphorus ligands to uranyl bound to carbon ligands and the formation of nanoparticulate uraninite occurred in the sediment samples during storage.
Resumo:
BACKGROUND.: High serum phosphate has been identified as an important contributor to the vascular calcification seen in patients with chronic kidney disease (Block et al., Am J Kidney Dis 1998; 31: 607). In patients on hemodialysis, elevated serum phosphate levels are an independent predictor of mortality (Block et al., Am J Kidney Dis 1998; 31: 607; Block, Curr Opin Nephrol Hypertens 2001; 10: 741). The aim of this study was to investigate whether an elevated serum phosphate level was an independent predictor of mortality in patients with a renal transplant.
METHODS.: Three hundred seventy-nine asymptomatic renal transplant recipients were recruited between June 2000 and December 2002. Serum phosphate was measured at baseline and prospective follow-up data were collected at a median of 2441 days after enrolment.
RESULTS.: Serum phosphate was significantly higher in those renal transplant recipients who died at follow-up when compared with those who were still alive at follow-up (P<0.001). In Kaplan-Meier analysis, serum phosphate concentration was a significant predictor of mortality (P=0.0001). In multivariate Cox regression analysis, serum phosphate concentration remained a statistically significant predictor of all-cause mortality after adjustment for traditional cardiovascular risk factors, estimated glomerular filtration rate, and high sensitivity C reactive protein (P=0.036) and after adjustment for renal graft failure (P=0.001).
CONCLUSIONS.: The results of this prospective study are the first to show that a higher serum phosphate is a predictor of mortality in patients with a renal transplant and suggest that serum phosphate provides additional, independent, prognostic information to that provided by traditional risk factors in the risk assessment of patients with a renal transplant.
Resumo:
In this paper, we attempt to reconcile contingency and institutional fit approaches concerning the organization-environment relationship. While prior scholarly research has examined both theories and compared their impacts on organizational fit and performance, we lay the groundwork for a meta-fit approach by investigating how contingency and institutional fit interact to influence firm performance. We test our theoretical framework using a dataset of 3,259 respondents from 1,904 companies regarding task environmental demands and institutional demands on organizational design across a broad range of industries and firm size classes. Our results show that contingency and institutional fit provide complementary and interdependent explanations of firm performance. Importantly, our findings indicate that for firms under conditions of “quasi-fit” rather than perfect contingency fit or optimal institutional fit, improvements in contingency and/or institutional fit will result in better performance. However, firms with high contingency fit are less vulnerable to deviation from institutional fit in the formation of firm performance, while firms with perfect institutional fit will slightly decrease their performance when they strive to achieve contingency fit.
Resumo:
Purpose: F-18-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) has benefits in target volume (TV) definition in radiotherapy treatment planning (RTP) for non small-cell lung cancer (NSCLC); however, an optimal protocol for TV delineation has not been determined. We investigate volumetric and positional variation in gross tumor volume (GTV) delineation using a planning PET/CT among three radiation oncologists and a PET radiologist.
Resumo:
RATIONALE, AIMS AND OBJECTIVES: Health care services offered to the public should be based on the best available evidence. We aimed to explore pharmacy tutors' and trainees' views on the importance of evidence when making decisions about over-the-counter (OTC) medicines and also to investigate whether the tutor influenced the trainee in practice.
METHODS: Following ethical approval and piloting, semi-structured interviews were conducted with pharmacy graduates (trainees) and pharmacist tutors. Transcribed interview data were entered into the NVivo software package (version 10), coded and analysed via thematic analysis.
RESULTS: Twelve trainees (five males, seven females) and 11 tutors (five males, six females) participated. Main themes that emerged were (in)consistency and contradiction, confidence, acculturation, and continuation and perpetuation. Despite having an awareness of the importance and potential benefits, an evidence-based approach did not seem to be routinely or consistently implemented in practice. Confidence in products was largely derived from personal use and patient feedback. A lack of discussion about evidence was justified on the basis of not wanting to lessen patient confidence in requested product(s) or possibly negating the placebo effect. Trainees became acculturated to 'real-life' practice; university teaching and evidence was deemed less relevant than meeting customer expectations. The tutor's actions were mirrored by their trainee resulting in continuation and perpetuation of the same professional attitudes and behaviours.
CONCLUSIONS: Evidence appeared to have limited influence on OTC decision making. The tutor played a key role in the trainee's professional development. More work could be performed to investigate how evidence can be regarded as relevant and something that is consistently implemented in practice.
Resumo:
Hands can be a vector for transmitting pathogenic microorganisms to foodstuffs and drinks, and to the mouths of susceptible hosts. Hand washing is the primary barrier to prevent transmission of enteric pathogens via cross contamination from infected persons. Conventional hand washing involves the use of warm water, soap and friction to remove dirt and microorganisms. Over recent years there has been an increasing availability of hand sanitizing products for use when water and soap are unavailable. The aim of this systematic review was to collate scientific information on the efficacy of hand sanitizers compared to hand washing with soap and water for the removal of foodborne pathogens from the hands of food handlers. An extensive literature search was carried out using three electronic databases - Web of Science, Scopus and PubMed. Twenty-eight scientific publications were ultimately included in the review. Analysis of the literature showed various limitations in the scientific information due to the absence of a standardized protocol to evaluate efficacy of hand products, and variation in experimental conditions applied in different studies. Despite the existence of conflicting results, scientific evidence seems to support the historical scepticism about the use of water-less hand sanitizers in food preparation settings. Water and soap appear to achieve greater removal of soil and microorganisms than water-less products from hands. None of the hand sanitizers tested in the literature seemed to achieve complete inactivation or removal of all foodborne pathogens tested, and the presence of food debris significantly affected inactivation rates of hand products.