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A time-resolved flow cytometer capable of measuring a luminescence with a decay time in the range of 10 p s to 2 ms, typical for some lanthanide chelates, is presented. The instrument permits acquisition of conventional light scatter and prompt fluorescence signals as well as detection of slowly decaying luminescence by a photon counting unit for a selectable time period of 1 p s to 1 ms. During photon counting, the laser beam is turned off by an acoustooptic deflector. The design of a flow chamber with an average geometrical light collection efficiency of 35% over a distance of 1.7 mm is presented and analyzed by ray tracing. A pulse processing system featuring digital integration of the conventional signals and a transputer system for the acquisition and the transfer of the measured parameter values to a host computer is described.Instrument function is verified with lyophilized human lymphocytes stained for the CD8 antigen with dye-loaded liposomes. Quantitation of cell-associated europium chelate fluorescence, displaying a decay time of 1.6 ms, is demonstrated. Elimination of fast decaying background emission generated by DNA-associated ethidium bromide is shown. The background generated by instrument components in the time-gated measurement channel is characterized, and measures for its complete elimination are discussed. In the work presented here, the implementation of an instrument concept for the time-resolved measurement of lanthanide chelate luminescence in flow cytometry, introduced and evaluated in the accompanying paper (3), is described. In this time-resolved flow cytometry (TR-FCM) technique, slowly decaying lanthanide chelate luminescence is detected after a cell has left the laser intersection point. An optical switch turns off the laser beam during the fluorescence detection period in order to eliminate fast decaying cellular or instrument luminescence excited by residual scattered laser light.The design of a n optical system permitting the detection of conventional light scatter and prompt fluorescence signals, as well as the acquisition of one slowly decaying luminescence over a time period of 1 ms, is described. A data acquisition system featuring photon counting detection of the lanthanide chelate fluorescence and a transputer-based pulse-processing unit is presented. The preparation of antibody-coupled liposomes loaded with europium chelates is described. Finally, the performance of the instrument is assessed, particularly in terms of the background suppression efficiency achieved by the optical switch. Experimental data demonstrating the quantification of europium

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Police crash reports are often the main source for official data in many countries. However, with the exception of fatal crashes, crashes are often underreported in a biased manner. Consequently, the countermeasures adopted according to them may be inefficient. In the case of bicycle crashes, this bias is most acute and it probably varies across countries, with some of them being more prone to reporting accidents to police than others. Assessing if this bias occurs and the size of it can be of great importance for evaluating the risks associated with bicycling. This study utilized data collected in the COST TU1101 action "Towards safer bicycling through optimization of bicycle helmets and usage". The data came from an online survey that included questions related to bicyclists' attitudes, behaviour, cycling habits, accidents, and patterns of use of helmets. The survey was filled by 8655 bicyclists from 30 different countries. After applying various exclusion factors, 7015 questionnaires filled by adult cyclists from 17 countries, each with at least 100 valid responses, remained in our sample. The results showed that across all countries, an average of only 10% of all crashes were reported to the police, with a wide range among countries: from a minimum of 0.0% (Israel) and 2.6% (Croatia) to a maximum of a 35.0% (Germany). Some factors associated with the reporting levels were type of crash, type of vehicle involved, and injury severity. No relation was found between the likelihood of reporting and the cyclist's gender, age, educational level, marital status, being a parent, use of helmet, and type of bicycle. The significant under-reporting - including injury crashes that do not lead to hospitalization - justifies the use of self-report survey data for assessment of bicycling crash patterns as they relate to (1) crash risk issues such as location, infrastructure, cyclists' characteristics, and use of helmet and (2) strategic approaches to bicycle crash prevention and injury reduction.

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In a collaboration between the University of Texas (software) and the University of Zürich (hardware) a compact, automatic system for biplane quantitative coronary arteriography was developed. The system is based on a 35 mm film projector, a slow-scan CCD-camera (image digitizing) and a computer workstation (Apollo DN 3000, image storage and processing). A new calibration procedure based on two fixed reference points in the center of the image intensifier was used (isocenter technique). Contour detection of coronary arteries was carried out in biplane projection using a geometric-densitometric edge-detection algorithm. The proximal and distal luminal areas, as well as the minimal luminal area of the stenotic vessel segment were determined. Accuracy and precision were determined from precision drilled holes in a plexiglas cube which were filled with 50%, 75% and 100% contrast medium. The diameter of the holes ranged from 0.5 to 5.0 mm. The mean difference and the standard deviation of the differences between the true and the measured diameters were 0.12 +/- 0.14 mm for plane A and 0.26 +/- 0.17 mm for plane B, respectively. After a second order correction the mean difference amounted to 0.02 +/- 0.09 mm for plane A and 0.02 +/- 0.12 mm for plane B, respectively. Intra- and interobserver variability were evaluated in 5 patients (age 60 +/- 10 years) with coronary artery disease using 16 normal and 5 stenotic vessel segments (cross-sectional area ranging from 0.8 to 8.7 mm2). Two independent observers analyzed the same vessel segment twice. Intraobserver variability expressed as the standard error of estimate in percent of the mean angiographic vessel area (SEE) amounted to 2.1% for observer 1 and 4.4% for observer 2, respectively. Interobserver variability expressed as SEE was 4.1% for measurement 1 and 3.6% for measurement 2, respectively.

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OBJECTIVES: The influence of low-dose alcohol intake on reflexive visually guided saccades was investigated. METHODS: 40 healthy human subjects were orally given alcohol resulting in lowdose alcohol concentration (less than 0.8‰) blood alcohol concentration. Before and after exposure, horizontal saccadic eye movements were recorded at several points in time. The recordings were evaluated with regard to accuracy of the eye movements, latency, the peak eye velocity and the time constant that characterizes the main sequence. The results were compared to recordings from a reference group. RESULTS: It was found that the saccadic eye movement was clearly altered by low-dose alcohol intake. However, its characteristics were not unambiguously pathological when compared to the reference group, even though the subjects reported a moderate to strong effect of alcohol and there were clear signs of inebriation. CONCLUSIONS: The findings render the evaluation of saccades unsuitable as a simple test for the detection of low-dose alcohol intake. Methods: 40 healthy human subjects were orally given alcohol resulting in low-dose alcohol concentration (less than 0.8 ‰) blood alcohol concentration. Before and after exposure, horizontal saccadic eye movements were recorded at several points in time. The recordings were evaluated with regard to accuracy of the eye movements, latency, the peak eye velocity and the time constant that characterizes the main sequence. The results were compared to recordings from a reference group.Results: It was found that the saccadic eye movement was clearly altered by low-dose alcohol intake.However, its characteristics were not unambiguously pathological when compared to the reference group, even though the subjects reported a moderate to strong effect of alcohol and there were clear signs of inebriation. Conclusions:The findings render the evaluation of saccades unsuitable as a simple test for the detection of low-dose alcohol intake.