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61.
62.
Paulo Pereira Bertil Magnusson Elvar Theodorsson James O. Westgard Pedro Encarnação 《Accreditation and quality assurance》2016,21(1):25-32
The risk of misclassifying infected individuals as healthy constitutes a crucial challenge when screening blood donors by means of immunoassays. This risk is especially challenging when the numerical results are close to the clinical decision level, i.e. in the ‘grey zone’. The concept of using measurement uncertainty for evaluating the ‘grey zone’ has previously not been systematically applied in this context. This article explains methods, models and empirical (top-down) approaches for the calculation of measurement uncertainty using results from a blood bank according to the internationally accepted GUM principles, focusing on uncertainty sources in the analytical phase. Of the different approaches available, the intralaboratory empirical approaches are emphasised since modelling (bottom-up) approaches are impracticable due to the lack of reliable model equations for immunoassays. Different methods are applied to estimate the measurement uncertainty for the Abbott Prism® HCV immunoassay. The expanded uncertainty obtained at the clinical decision level from the intralaboratory empirical approach was 36 %. The estimated uncertainty was used to set acceptance and rejection zones following the procedure set in the Eurachem guideline, emphasising the need to minimise the occurrence of false negatives. 相似文献
63.
Antonio Menditto Marina Patriarca Bertil Magnusson 《Accreditation and quality assurance》2007,12(1):45-47
Clear definitions of basic terms, used to describe the quality of measurements, is essential for communication among scientists
as well as when reporting measurement results to clients. Even if appropriate definitions are given in international standards
and guidelines, the understanding of some basic terms sometimes proves difficult. The reasons for this are various, e.g.,
the same words being defined rather differently in encyclopaedias and in international standards as well as concepts, well
established in some languages, that may be relatively new in other national communities and at large in the international
one. Here we present a matrix intended to clarify the relationships between the type of error affecting an analytical measurement,
the respective qualitative concepts (performance characteristics) and their quantitative expression.
相似文献
Antonio MendittoEmail: |
64.
Lind P Boström D Carlsson M Eriksson A Glimsdal E Lindgren M Eliasson B 《The journal of physical chemistry. A》2007,111(9):1598-1609
Optical power limiting and luminescence properties of two Pt(II) complexes with thiophenyl and phenyl groups in the ligands, trans-Pt(P(n-Bu)3)2(C[triple bond]C-Ar)2, where Ar = -C4H2S-C[triple bond]C-p-C6H4-n-C5H11 (1) and -p-C6H4-C[triple bond]C-C4H3S (2), have been investigated. The fluorescence lifetimes were found to be on the sub-nanosecond time scale, and the quantum yields were low, in accord with fast intersystem crossing from the excited singlet to triplet manifold. The phosphorescence lifetimes of 1 and 2 were shorter than that of a Pt(II) complex having two phenyl groups in the ligands. In order to elucidate the C-Pt bonding nature in the ground state, the 13C NMR chemical shift of the carbon directly bonded to Pt, the coupling constants 1JPtC, 2JPtC, and 1JPtP, and IR nuC[triple bond]C wavenumbers were obtained for 1, 2, and three other trans-diarylalkynyl Pt(II) complexes. X-ray diffraction data of 1 and 2 and density functional theory calculated geometries of models of 1, 2, and trans-Pt(P(n-Bu)3)2(C[triple bond]C-p-C6H4-C[triple bond]C-C6H5)2 (3) show that 1 preferably exists in a different conformation from that of 2 and 3. The variations in photophysical, NMR, and IR data can be rationalized by differences in geometry and pi-backbonding from Pt to the alkynyl ligand. 相似文献
65.
We prove for abelian varieties a global form of Denef and Loeser?s motivic monodromy conjecture, in arbitrary characteristic. More precisely, we prove that for every tamely ramified abelian variety A over a complete discretely valued field with algebraically closed residue field, its motivic zeta function has a unique pole at Chai?s base change conductor c(A) of A, and that the order of this pole equals one plus the potential toric rank of A. Moreover, we show that for every embedding of Q? in C, the value exp(2πic(A)) is an ?-adic tame monodromy eigenvalue of A. The main tool in the paper is Edixhoven?s filtration on the special fiber of the Néron model of A, which measures the behavior of the Néron model under tame base change. 相似文献
66.
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68.
Louis Halle Rowen 《Israel Journal of Mathematics》1989,65(3):273-283
By means of generic methods, an example is given of a local (but not Noetherian)π-regular ringR, over which the ring of 2 × 2 matrices isnot π-regular. Also a cyclic indecomposable (left) module over a right Artinian ring is exhibited, whose endomorphism ring is not
local.
This research was supported in part by the Israel Committee for Basic Research.
An erratum to this article is available at . 相似文献
69.
Freddy Sthlberg Jens Mogelvang Carsten Thomsen Bo Nordell Max Stubgaard Anders Ericsson Gran Sperber Dan Greitz Henrik Larsson Ole Henriksen Bertil Persson 《Magnetic resonance imaging》1989,7(6):655-667
The aim of this study was to establish a rapid method for in vivo quantification of a large range of flow velocities using phase information. A basic gradient-echo sequence was constructed, in which flow was encoded along the slice selection direction by variation of the amplitude of a bipolar gradient without changes in sequence timings. The influence of field inhomogeneities and eddy currents was studied in a 1.5 T scanner. From the basic sequence, interleaved sequences for calibration and in vivo flow determination were constructed, and flow information was obtained by pairwise subtraction of velocity-encoded from velocity non-encoded phase images. Calibration was performed in a nongated mode using flow phantoms, and the results were compared with theoretically calculated encoding efficiencies. In vivo flow was studied in healthy volunteers in three different areas using cardiac gating; central blood flow in the great thoracic vessels, peripheral blood flow in the popliteal vessels, and flow of cerebrospinal fluid (CSF) in the cerebral aqueduct. The results show good agreement with results obtained with other techniques. The proposed method for flow determination was shown to be rapid and flexible, and we thus conclude that it seems well suited for routine clinical MR examinations. 相似文献
70.
Formal hydride ion displacement readily occurs in 4,6-dinitro-benzofuroxan and -benzofurazan. This process provides a simple two-step synthesis of some new 7-substituted-4,6 dinitro derivatives. 相似文献