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Digitale Medien

Cyclic variation pattern of cerebral blood flow velocity and postconceptional age (1994)

Michel, E. ; Zernikow, B. ; Steck, J. ; [weitere]

Springer

European journal of pediatrics 153 (1994), S. 751-755

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ISSN: 1432-1076

Schlagwort(e): Autoregulation ; Cerebral blood flow velocity ; Doppler ; Newborn ; Nonlinear control theory

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract In preterm neonates, the risk for intracerebral haemorrhage is linked to immaturity of cerebral autoregulation. The preterm's 2–5/min cyclic variation pattern of cerebral blood flow velocity is thought to reflect the degree of immaturity of autoregulation — a speculation to be tested. In a cross-sectional study 15 infants (gestational age 26–40 weeks, postconceptional age (PCA) 26–42 weeks, age 1–99 days were investigated. We performed a 10 min pulsed Doppler tracing on an internal carotid artery by means of a computer controlled 5 MHz Duplex device. Systolic velocity (Vs) was recorded pulse by pulse. After appropriate data transformation, in all infants the Fast Fourier Transform of the time course of Vs revealed the presence of a 2–5/min cyclic variation pattern (one sample z-test,P〈0.0001). There was no significant correlation between proportionate spectral power of the 2–5/min frequency band and either PCA (r=0.23,P=0.42) or age (r=0.41,P=0.13). Between 26 and 42 weeks PCA, the cycling phenomenon is constant thus not reflecting cerebral maturation, and its presence does not mean immaturity of cerebral autoregulation.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01954493

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Digitale Medien

Parallelization of quantum mechanical integral calculations (1992)

Kindermann, S. ; Michel, E. ; Otto, P.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Computational Chemistry 13 (1992), S. 414-422

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ISSN: 0192-8651

Schlagwort(e): Computational Chemistry and Molecular Modeling ; Biochemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Informatik

Notizen: In ab initio Hartree - Fock crystal orbital calculations of chemical and physical properties of polymers, the huge number of two-electron integrals restricts the size of the elementary cell. Therefore, the question arises how the storage and computation resources of modern parallel supercomputers can be exploited. In this work, we report the parallelization of the one- and two-electron integral programs, respectively, for the parallel computer SUPRENUM. A short description of the hardware and software environment of this supercomputer is given. The results are discussed with respect to speed-up and efficiency.

Zusätzliches Material: 8 Ill.