Calibration System (calibration + system)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

A standardized procedure for quantitation of CD11b on polymorphonuclear neutrophil by flow cytometry: potential application in infectious diseases

INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 3 2004
V. Latger-Cannard
Summary An up-regulation of the surface marker CD11b has been demonstrated during polymorphonuclear (PMN) cell activation. CD11b over-expression is often associated with inflammation and is considered as an early marker of infection. However, the absence of standardized assay and the variability of preanalytical settings leading to PMN artifactual activation have compromised the interest of this marker. In the present study a standardized quantitative flow cytometry assay directly performed in whole blood has been used to determine CD11b expression on PMN cells. The results indicate that quantitative flow cytometry can provide consistent CD11b density values between laboratories provided that a calibration system is used including specific calibrators, reagents and protocols. This method allowed us to evidence an up-regulation of CD11b expression for infected patients. This quantitation is a standardized and potentially useful method in clinical situations implying quantitative CD11b expression variations. [source]

High-precision calibration of spectrographs

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2010
T. Wilken
ABSTRACT We present the first stringent tests of a novel calibration system based on a laser frequency comb (LFC) for radial velocity measurements. The tests were obtained with the high-resolution, optical spectrograph, High Accuracy Radial velocity Planet Searcher. By using only one echelle order, we obtain a calibration repeatability of 15 cm s,1 for exposures that are several hours apart. This is comparable with a simultaneous calibration using a Th,Ar lamp that makes use of all 72 echelle orders. In both cases, the residuals are compatible with the computed photon noise. Averaging all LFC exposures, recorded over a few hours, we could obtain a calibration curve with residuals of 2.4 m s,1. Thanks to the adjustable and optimally chosen line density of the LFC, we resolve a periodicity of 512 pixels in the calibration curve that is due to the manufacturing process of the CCD mask. Previous Th,Ar calibration was unable to resolve these systematic deviations, resulting in a deviation of up to 70 m s,1 from the true calibration curve. In future, we hope to be able to make use of all echelle orders in order to obtain a calibration repeatability below 1 cm s,1 and absolute calibration within a few m s,1. [source]

Monitoring the scale factor of the PICARD SODISM instrument

ASTRONOMISCHE NACHRICHTEN, Issue 5 2008
P. Assus
Abstract The SODISM Telescope of the PICARD Space mission will perform diameter measurements by directly imaging the Sun on a CCD camera. An internal calibration system allows us to follow scale factor variations induced by instrument deformations resulting from temperature fluctuations on orbit or from others causes. We present this calibration system in this paper as well as some simulations on how to correct observations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]