1,354,100 research outputs found
DEVELOPMENT OF A REFERENCE METHOD FOR THE ABSOLUTE MEASURING OF FLUORESCENCE IN BIOLOGICAL ANALYSIS
Get PDFThe research presented here was aimed to develop a method traceable to SI to compare the absolute fluorescence intensity measured by different instruments. This is due to the fact that the most common instruments use arbitrary measurement units. Each measure strictly depends on the technical intrinsic properties of the single instrument, hence the use of suitable reference materials is necessary to define its calibration scale.
To overcome this problem, it is necessary to define a reliable and universal measurement unit allowing to measure the absolute fluorescence intensity, whichever system is used, independently from the reference materials which are used.
In the present work, a protocol that permits the comparison of data taken with different fluorescence instruments has been developed
The relationship between the arbitrary unit of these instruments and the molecule numbers of the standard reference material used has been studied.
This allows the transformation from arbitrary unit to MESF, i.e. MOLECULAR EQUIVALENTS OF SOLUBLE FLUOROCHROME [1].
The standard reference fluorescence material used was Fluorescein.
Standard reference materials of Fluorescein were used to ensure the traceability of measurements results.
The work goals were to obtain: a method to prepare fluorescein solutions of calibration; characterization of fluorescence instruments ad their calibration; study of a measurement method of the calibration samples and calculation of their uncertainty budget ,expressed in number of molecules of fluorescein, (NF).
The final work goal was to obtain an uncertainty budget for measurements, expressed in equivalent number of molecules of fluorescein (MESF) for each used instrument..
By applying this method It has been possible to compare different measurements, using different fluorescence instruments
Traffic engineering with OSPF-TE and RSVP-TE: Flooding reduction techniques and evaluation of processing cost
No full textThis paper considers two important aspects related to the control plane of Traffic Engineered IP/MPLS networks: the "flooding reduction" mechanisms and the evaluation of processing cost for signaling and routing protocols. The flooding reduction mechanisms are needed to reduce the amount of information exchanged by Traffic Engineering enabled routing protocols. The trade-off between the amount of information exchanged and the network performance (connection blocking probability) is discussed in the light of specific aspects of OSPF-TE routing protocol and RSVP-TE signaling protocol. Different mechanisms are analyzed and a suggestion is given for the best one. The dynamic aspects related to the time needed to distribute the routing and signaling information are considered. Finally, the combined processing cost of routing and signaling is analyzed, and the possible bottlenecks of the architecture are discussed. It is worth mentioning that the discussed results have been derived not only with simulation/analysis but also with measurements coming from a testbed implementation. (c) 2005 Elsevier B.V. All rights reserved
ALL FIBER STRAIN SENSOR BASED ON THE LASER SELF-MIXING EFFECT
No full textWe present the development of a no-contact sensor based on the laser-self-mixing effect for the simultaneous measurement of the linear and angular (yaw and pitch) degrees-of-freedom of the motion of a moving stage. The sensor is made up of three laser diodes with integrated monitor photodiodes and a plane mirror target. The measurement principle is described and a series of experiments is performed to test the proposed method by direct comparison with a reference meter system. Finally, the sensor is tested under complex displacement to validate the feasibility of simultaneous measurements of more than one degree-of-freedom. The proposed technique makes the system easier to align with respect to the traditional interferometric systems and no further optical elements are required in the laser head except for the laser chip and its integrated photodiode, thus providing an effective compact and low-cost motion control system
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