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排序方式: 共有244条查询结果,搜索用时 265 毫秒
21.
Birgitte Wuyts Dirk Bernard Nele Van Den Noortgate Johan Van De Walle Bruno Van Vlem Rita De Smet Frank De Geeter Raymond Vanholder Jean-Claude Libeer Joris Delanghe 《Accreditation and quality assurance》2004,10(1-2):15-19
When the calibration of a routine measurement procedure is traced back to metrological higher order, a significant discrepancy can occur between the analytical conditions of the routine measurement and the analytical conditions that were used in the clinical studies upon which the decision-making criteria are based. This can lead to serious interpretation errors with possible dramatic consequences for patients. The calibration of the creatinine Jaffé method is an excellent example of the importance of medical traceability. The compensated Jaffé method correlated accurately with the reference method and the compensated Jaffé creatinine clearance (CrCl), Cockroft and Gault and MDRD with the 51Cr EDTA clearance. The Schwartz estimate based upon the compensated Jaffé and enzymatic method overestimated, while uncompensated Jaffé slightly underestimated glomerular filtration rate (GFR). The situation in children is complex since serum creatinine concentrations are much lower in infants, rendering tubular secretion relatively more important. Low-molecular weight proteins have been suggested to replace serum creatinine as a marker for GFR. -trace protein, cystatin C, and 2-microglobulin showed good correlation with GFR. However, care should be taken in patients presenting with some malignant tumors, since significant increases of cystatin C in patients with metastatic melanoma or colorectal cancer has been reported.Presented at the 9th Conference on Quality in the Spotlight, 18-19 March 2004, Antwerp, Belgium 相似文献
22.
Winé G Matta J Tessonnier JP Pham-Huu C Ledoux MJ 《Chemical communications (Cambridge, England)》2003,(4):530-531
Beta zeolite supported on silicon carbide, with high thermal conductivity and high mechanical strength, was successfully used as an active and stable catalyst for Friedel-Crafts reactions in a fixed bed configuration. 相似文献
23.
M. Ledoux 《Journal of statistical physics》2000,100(5-6):871-892
This paper describes some of the analytic tools developed recently by Ghirlanda and Guerra in the investigation of the distribution of overlaps in the Sherrington–Kirkpatrick spin glass model and of Parisi's ultrametricity. In particular, we introduce to this task a simplified (but also generalized) model on which the Gaussian analysis is made easier. Moments of the Hamiltonian and derivatives of the free energy are expressed as polynomials of the overlaps. Under the essential tool of self-averaging, we describe with full rigour, various overlap identities and replica independence that actually hold in a rather large generality. The results are presented in a language accessible to probabilists and analysts. 相似文献
24.
Wolfgang J. Philipp Pierre van Iwaarden Heinz Schimmel Nele Meeus Nadine Kollmorgen 《Accreditation and quality assurance》2007,12(3-4):134-138
The reliability of reference materials (RMs) depends on properties such as fitness, robustness, commutability, stability and
homogeneity. The development of RMs for microbiological analysis is especially challenged through questions around the stabilisation
and recovery of viable cells, the dispersion of precise numbers of cells, matrix effects and, when using molecular techniques,
the presence of nucleic acids (e.g. DNA) of dead and live target organisms. However, RMs are indispensable tools for quality
control in microbiological analysis. The Institute for Reference Materials and Measurements (IRMM), as part of the European
Commission, concentrates its efforts on the development of RMs to support the development, implementation and monitoring of
EU legislation. A special focus is given to highly precise RMs for presence/absence and enumeration tests in microbiological
food and water analysis. Another group of new RMs certified by the IRMM comprise DNA-based materials to control the identity
of micro-organisms in qualitative assays. All of these activities serve to improve quality control in microbiological analysis.
Presented at ‘BERM-10’, April 2006, Charleston, SC, USA. 相似文献
25.
26.
Adriana DoyleAlvaro Saavedra Maria Luiza B. TristãoMárcio Nele Ricardo Q. Aucélio 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(5):368-372
Official guidelines to perform chlorine determination in crude oil are (i) American Society for Testing and Materials (ASTM) D6470, which is based on the extraction of water from the oil and subsequent determination of the chloride by potentiometry, (ii) ASTM D3230, that measures the conductivity of a solution of crude oil in a mixture of organic solvents and (iii) US Environmental Protection Agency (EPA) 9075 that uses energy dispersive X-ray fluorescence spectrometry to quantify chlorine and it is applicable for the range from 200 μg g− 1 to percent levels of the analyte. The goal of this work is to propose method to quantify lower amounts of chlorine in crude oil using energy dispersive X-ray fluorescence spectrometry using a simple calibration strategy. Sample homogenization procedure was carefully studied in order to enable accurate results. The calibration curve was made with standards prepared by diluting aqueous NaCl standard in glycerin. The method presented a linear response that covers the range from 8 to at least 100 μg g− 1 of chlorine. Chlorine in crude oil samples from Campos Basin - Brazil were quantified by the proposed method and by potentiometry after extraction of chlorine from the oil. Results achieved using both methods were statistically the same at 95% confidence level. 相似文献
27.
This paper studies an inequality of H. P. Rosenthal for vector valued random variables, its relations with some geometric
properties of Banach spaces and its applications to the study of the central limit theorem in Banach spaces.
相似文献
28.
Tessonnier JP Louis B Walspurger S Sommer J Ledoux MJ Pham-Huu C 《The journal of physical chemistry. B》2006,110(21):10390-10395
On the basis of our previous H/D exchange studies devoted to the quantification of the number of Br?nsted acid sites in solid acids, we report here an innovative approach to determine both the amount and the localization of Mo atoms inside the Mo/ZSM-5 catalyst, commonly used for the methane dehydroaromatization reaction. The influence of Mo introduction in the MFI framework was studied by means of BET, X-ray diffraction, 27Al magic angle spinning NMR, NH3 temperature-programmed desorption, and H/D isotopic exchange techniques. A dependence was found between the decrease of acidic OH groups and the Mo content. Depending on the Si/Al ratio of the zeolite, i.e., the proximity of two Br?nsted acid sites, the Mo atoms substitute a different number of OH groups. Consequently, a chemical structure was proposed to describe the geometry of the Mo complex in the channels of the ZSM-5 zeolite. 相似文献
29.
Michel Ledoux 《Journal of Theoretical Probability》2018,31(4):2366-2375
Let \({\widetilde{H}}_N\), \(N \ge 1\), be the point-to-point last passage times of directed percolation on rectangles \([(1,1), ([\gamma N], N)]\) in \({\mathbb {N}}\times {\mathbb {N}}\) over exponential or geometric independent random variables, rescaled to converge to the Tracy–Widom distribution. It is proved that for some \(\alpha _{\sup } >0\), with probability one, and that \(\alpha _{\sup } = \big ( \frac{3}{4} \big )^{2/3}\) provided a commonly believed tail bound holds. The result is in contrast with the normalization \((\log N)^{2/3}\) for the largest eigenvalue of a GUE matrix recently put forward by E. Paquette and O. Zeitouni. The proof relies on sharp tail bounds and superadditivity, close to the standard law of the iterated logarithm. A weaker result on the liminf with speed \((\log \log N)^{1/3}\) is also discussed.
相似文献
$$\begin{aligned} \alpha _{\sup } \, \le \, \limsup _{N \rightarrow \infty } \frac{{\widetilde{H}}_N}{(\log \log N)^{2/3}} \, \le \, \Big ( \frac{3}{4} \Big )^{2/3} \end{aligned}$$
30.