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  • 1
    ISSN: 1432-072X
    Keywords: Key words: Mechanism of penicillin action – Staphylococci – Cross-wall welding – Bacteriolysis – Morphogenetic resistance system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. In log-phase cells of staphylococci, cultivated under high, ``non-lytic'' concentrations of penicillin G, there occurred a novel killing process hitherto hidden behind seemingly bacteriostatic effects. Two events are essential for the appearance of this ``hidden death'': (i) the failure of the dividing cell to deposit enough fibrillar cross-wall material to be welded together, and (ii) a premature ripping up of incomplete cross walls along their splitting system. ``Hidden death'' started as early as 10 – 15 min after drug addition, already during the first division cycle. It was the consequence of a loss of cytoplasmic constituents which erupted through peripheral slit-like openings in the incomplete cross walls. The loss resulted either in more or less empty cells or in cell shrinkage. These destructions could be prevented by raising the external osmotic pressure. In contrast, the conventional ``non-hidden death'' occurred only much later and exclusively during the second division cycle and mainly in those dividing cells, whose nascent cross walls of the first division plane had been welded together. These welding processes at nascent cross walls, resulting in tough connecting bridges between presumptive individual cells, were considered as a morphogenetic tool which protects the cells, so that they can resist the otherwise fatal penicillin-induced damages for at least an additional generation time (``morphogenetic resistance system''). Such welded cells, in the virtual absence of underlying cross-wall material, lost cytoplasm and were killed via ejection through pore-like wall openings or via explosions in the second division plane and after liberation of their murosomes, at it was the case in the presence of low, ``lytic'' concentrations of penicillin. Bacteriolysis did not cause any of the hitherto known penicillin-induced killing processes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Computing 53 (1994), S. 259-276 
    ISSN: 1436-5057
    Keywords: 65F30 ; 65G05 ; 65G10 ; 68B99 ; Maximum accuracy ; parallel runtime system ; transputer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Die meisten numerischen Algorithmen verwenden Gleitpunktoperationen für Matrizen und Vektoren. Auf Parallelrechnern sollten solche Algorithmen schnellund zuverlässig durchgeführt werden, um zeitaufwendige Fehleranalysen zu vermeiden. Die XSC-Sprachen (Spracherweiterungen für erweitertes wissenschaftliches Rechnen, englisch: eXtendedScientificComputation) sind für diesen Zweck gut geeignet, da sie den Entwurf numerischer Algorithmen unterstützen, die korrekte und automatisch verifizierte Ergebnisse liefern. Dieses Ziel wird durch eine Arithmetik mit maximaler Genauigkeit (insbesondere für Vektor- und Matrixoperationen), hochgenaue Standardfunktionen und exakte Auswertung von Skalarproduktausdrücken erreicht. Innerhalb derESPRIT Parallel Computing Action wurde eine XSC-Sprache, PASCAL-XSC, auf einem Supercluster Transputer System unter dem Betriebs-system HELIOS implementiert. Parallele Algorithmen für rechenintensive und maximal genaue Matrix-operationen wurden auf verschiedenen Transputerarchitekturen implementiert und getestet. Wir werden einige Merkmale dieser Architekturen kurz beschreiben und einige Benchmarks für die verwendeten Algorithmen angeben. Diese Algorithmen bilden eine parallele C Laufzeitbibliothek für PASCAL-XSC (oder irgend eine andere XSC-Sprache, die eine C-Laufzeitbibliothek benutzt) und werden automatisch aufgerufen. Dies kann als Grundstock für eine implizite Parallelisierung in einer XSC-Sprache angesehen werden.
    Notes: Abstract The majority of numerical algorithms employs floating-point vector and matrix operations. On a parallel computer these algorithms should be solved fastand reliably in order to avoid a time-consuming error analysis. The XSC-languages (high-level language extensions for eXtended Scientific Computation) are well-suited for this purpose since they support the design of numerical algorithms delivering correct and automatically verified results. This goal is attained by an arithmetic with maximum accuracy (especially for vector and matrix operations), highly accurate standard functions, and exact evaluation of dot product expressions. Within theESPRIT Parallel Computing Action, one XSC-language, PASCAL-XSC, was implemented on a Supercluster Transputer System under the operating system HELIOS. Parallel algorithms for computationally intensive and maximally accurate matrix operations were implemented and tested on various transputer architectures. We will sketch some features of these architectures and present some benchmarks for the algorithms used. These algorithms form a parallel C runtime library of PASCAL-XSC (or any other XSC-language that uses a C runtime library) and are called automatically. This can be considered a basis for implicit parallelization in an XSC-language.
    Type of Medium: Electronic Resource
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