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- Khayat, Kamal H., et al.
(författare)
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Field-oriented test methods to evaluate structural build-up at rest of flowable mortar and concrete
- 2012
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Ingår i: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 45:10, s. 1547-1564
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Tidskriftsartikel (refereegranskat)abstract
- Thixotropy of flowable mortar and concrete is an important property that affects stability and form pressure characteristics. The increase in thixotropy can reduce lateral pressure on formwork systems. On the other hand, low thixotropy or a continuous casting is required to eliminate the formation of weak interface between lifts in multilayer casting. Thixotropy can be assessed by determining the rate of structural build-up at rest, which necessitates the use of simple and robust test methods to be quantified. Five field-oriented test methods that can be used for the determination of structural build-up at rest of mortar and concrete are proposed in this paper in an attempt to select a reliable field-oriented test. This includes the inclined plane (IP), portable vane (PV), undisturbed slump spread (USS), cone penetration (CP), and K-slump test methods. The repeatability of these test methods was determined four times using two concrete-equivalent mortars and two self-consolidating concretes (SCC) of different thixotropy levels. The IP, PV, and USS tests showed relative error (RE) values of 0.5-37 %. The CP test was successfully used to determine structural build-up of mortar; however, it was difficult to assess the thixotropy of concrete. The K-slump test exhibited a RE, less than 12 % for SCC mixtures with low thixotropy, but up to 76 % for highly thixotropic SCC. Good correlations were established among the various structural build-up indices determined from the proposed test methods and those determined by rheometric tests using various concrete.
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- Kuehni, C E, et al.
(författare)
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Factors influencing age at diagnosis of primary ciliary dyskinesia in European children.
- 2010
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Ingår i: The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology. - : European Respiratory Society (ERS). - 1399-3003. ; 36:6, s. 1248-58
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Tidskriftsartikel (refereegranskat)abstract
- Primary ciliary dyskinesia (PCD) is a hereditary disorder of mucociliary clearance causing chronic upper and lower airways disease. We determined the number of patients with diagnosed PCD across Europe, described age at diagnosis and determined risk factors for late diagnosis. Centres treating children with PCD in Europe answered questionnaires and provided anonymous patient lists. In total, 223 centres from 26 countries reported 1,009 patients aged < 20 yrs. Reported cases per million children (for 5-14 yr olds) were highest in Cyprus (111), Switzerland (47) and Denmark (46). Overall, 57% were males and 48% had situs inversus. Median age at diagnosis was 5.3 yrs, lower in children with situs inversus (3.5 versus 5.8 yrs; p < 0.001) and in children treated in large centres (4.1 versus 4.8 yrs; p = 0.002). Adjusted age at diagnosis was 5.0 yrs in Western Europe, 4.8 yrs in the British Isles, 5.5 yrs in Northern Europe, 6.8 yrs in Eastern Europe and 6.5 yrs in Southern Europe (p < 0.001). This strongly correlated with general government expenditures on health (p < 0.001). This European survey suggests that PCD in children is under-diagnosed and diagnosed late, particularly in countries with low health expenditures. Prospective studies should assess the impact this delay might have on patient prognosis and on health economic costs across Europe.
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- Stevens, Lesley A., et al.
(författare)
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Development and validation of GFR-estimating equations using diabetes, transplant and weight
- 2010
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Ingår i: Nephrology Dialysis Transplantation. - : Oxford University Press (OUP). - 1460-2385 .- 0931-0509. ; 25:2, s. 449-457
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Tidskriftsartikel (refereegranskat)abstract
- Methods. Linear regression was used to relate log-measured GFR (mGFR) to sex, race, diabetes, transplant, weight, various transformations of creatinine and age with and without interactions. Equations were developed in a pooled database of 10 studies [2/3 (N = 5504) for development and 1/3 (N = 2750) for internal validation], and final model selection occurred in 16 additional studies [external validation (N = 3896)]. Results. The mean mGFR was 68, 67 and 68 ml/min/ 1.73 m(2) in the development, internal validation and external validation datasets, respectively. In external validation, an equation that included a linear age term and spline terms in creatinine to account for a reduction in the magnitude of the slope at low serum creatinine values exhibited the best performance (bias = 2.5, RMSE = 0.250) among models using the four basic predictor variables. Addition of terms for diabetes and transplant did not improve performance. Equations with weight showed a small improvement in the subgroup with BMI < 20 kg/m(2). Conclusions. The CKD-EPI equation, based on creatinine, age, sex and race, has been validated and is more accurate than the MDRD study equation. The addition of weight, diabetes and transplant does not significantly improve equation performance.
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