M?glichkeiten zur lokalen Bewertung von SIMS-Elementverteilungen an der Ionenmikrosonde

Zusammenfassung Eine Ionenmikrosonde mit angeschlossenem Rechnersystem kann Elementverteilungsbilder von Oberflächen an Festkörpern liefern. Das Verfahren zur quantitativen Bewertung dieser SIMS-Elementverteilungen läßt sich in 2 Bereiche aufteilen: Bildaufnahme und Bildverarbeitung. Beide Teile beinhalten eine umfangreiche Hardware- und Softwareausstattung. Zur Unterstützung der Bildverarbeitung wird ein DEC-Rastergrafik-Farbdisplay-system VS-11 am Rechner PDP 11/34 betrieben. Das Softwarepaket läuft unter dem Betriebssystem RT-11 in overlay -Struktur.Das Bildaufnahme-Programm steuert den Primärionenstrahl der Ionenmikrosonde. Dieser Strahl rastert die gewünschte Analysenfläche punktförmig Zeile für Zeile ab, verursacht die Emission von Sekundärionen an jedem Bildpunkt und separiert den für die eingestellte Masse (Isotop) gewünschten Sekundärionenstrahl. Dieser Strom wird für jedes Bildelement digitalisiert und auf der Magnetplatte als Elementverteilungsbild (Isotop) abgelegt.Das Bildverarbeitungssystem zur Quantifizierung der gemessenen Verteilungen benutzt ein vereinfachtes Gleichgewichtsmodell. Es liefert die Empfindlichkeitsfaktoren, die zur Transformation der Bilder vom Intensitäts- in den Konzentrationsmaßstab benutzt werden.Dieser Beitrag befaßt sich schwerpunktmäßig mit verschiedenen Bewertungs- und Darstellungsmöglichkeiten der Elementverteilungsbilder auf dem Rastergrafik-Farbdisplaysystem und gibt Beispiele experimenteller Anwendungen.

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Possibilities for local estimation of SIMS-element distributions with the ion microprobe

Summary An ion microprobe with a coupled computer system supplies element distribution images for surface areas of solids. The procedure for quantitative estimation of SIMS element distributions is devided into 2 parts: image recording and image processing. Both parts cover an extensive equipment of hardware and software. To support image processing, a DEC raster graphic color display system VS-11 is linked to the computer PDP 11/34. A comprehensive software package, structured in overlay-technique, runs under the wide-spread operating system RT-11. The image recording program controls the primary beam of the ion microprobe. This beam scans the desired analysis area pixel by pixel and line by line, causes the emission of secondary ions for each pixel, and separates the mass (isotope) dependent secondary ion beam. This current is digitized and stored as an element (isotope) image on the hard disk.The image processing system for quantitative analysis is based on a simplified equilibrium model. It supplies sensitivity factors to transform the images from intensity to concentration scale.This paper is mainly devoted to various feasibilities of processing, estimating, and presenting the images on the raster graphic color display system and presents examples of experimental applications.

     

A comparison of projection-based model reduction concepts in the context of nonlinear biomechanics

Computational assistance gains increasing importance in the field of medical surgery. As an example, in the present work, we look at functional endoscopic sinus surgery. Simulations for surgery training programs or online support during surgeries require simulation tools which are characterized by a preferably short simulation time (real time) and a high degree of accuracy. The nonlinear finite element method is most suitable to yield qualitatively and quantitatively reliable results. The problem is, however, to achieve such results in real time. One possibility to reach both, short computational time and high accuracy, is to combine model reduction and finite element techniques. Therefore, in this paper, various projection-based model reduction methods are discussed and compared with respect to their possible application in biomechanics. The modal basis, the load-dependent Ritz and the proper orthogonal decomposition (POD) method were used to reduce the model of a cube under compression considering different material nonlinearities and large deformations. The POD method led to the lowest errors in displacement and stress while providing the largest reduction in CPU time. Further, the influence of different POD parameters was investigated. According to this study, the snapshots upon which the POD is based had to agree as closely as possible with the original deformation of the reduced system. The POD method applied to the finite element model of an inferior turbinate led to an adequate accuracy for surgery simulations within less than one-third of the computational time of the unreduced finite element simulation.     

Comparison between the oral and intravenous L-[1-13C]phenylalanine breath test for the assessment of liver function

To simplify the L-[1-13C]phenylalanine breath test which is used to assess liver function the tracer is usually given orally, and CO2 production rate is estimated. In 12 healthy volunteers and 10 liver cirrhotics we compared the oral approach with i.v. tracer administration combined with measurement of individual CO2 production rate. The 13CO2/12CO2 enrichment was assessed by isotope-ratio mass spectrometry. After i.v. [1-13C]phenylalanine application exhaled 13C recovery per minute peaked within 10 minutes (controls: 0.17 +/- 0.06%; cirrhotics: 0.05 +/- 0.02%, p < 0.01). The oral approach yielded comparable separation between 30-60 minutes, with average peak values being 0.18 +/- 0.03% and 0.06 +/- 0.03% (p < 0.01), respectively. Variable gastrointestinal resorption kinetics after oral application probably causes this difference.     

Advanced DSS for scheduling: software engineering aspects and the role of Eigenmodels

This paper describes an advanced decision support system for scheduling that is based on both, extensive knowledge about scheduling algorithms, and a new software engineering paradigm developed by the FAW. This paradigm uses an elaborate compromise between object-orientation, constraint processing, and functional capabilities, and supports distributed computing.The system has the capability to generate a model of itself. ThisEigenmodel is a directed graphG representing data structures (nodes ofG) and algorithms (edges ofG). The methods developed for scheduling problems can, on a higher level of abstraction, also be applied to the Eigenmodel itself. This can then be used for performance analysis andlearning aspects which will eventually provide the user with valuable information about the functioning and performance of the system, thus contributing to the envisioned new generation of decision support systems.1994 IEEE. Reprinted, with permission, fromProceedings of the 27th Annual Hawaii International Conference on Systems Sciences. Volume III Information Systems: Decision Support and Knowledge-Based Systems; ed. by J. F. Nunamaker and R. H. Sprague; Maui, Hawaii, 4–7 January 1994, pp. 290–299.The second author acknowledges support from the Deutsche Forschungsgemeinschaft under grant Mö446 1–3 and Sonderforschungsbereich 373.     

Book reviews

Communicated by Professor Zimmermann     

Toward the quantification of the 13CO2/12CO2 ratio in exhaled mouse breath with mid-infrared hollow waveguide gas sensors

Mouse sepsis models are used to gain insight into the complex processes involved with patients suffering from glucose metabolism disorders. Measuring the expiratory release of ¹³CO₂ after administering stable labeled ¹³C₆-glucose enables assessment of the in vivo integrity and functionality of key metabolic processes. In the present study, we demonstrate that Fourier transform infrared spectroscopy operating in the mid-infrared spectral regime (2–20 μm) combined with hollow waveguide gas sensing modules simultaneously serving as a miniaturized gas cell and as a waveguide are capable of quantitatively monitoring ¹³CO₂ enrichment levels in low volume mouse breath samples.