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The complex behaviour of cardiorespiratory dynamics is shown to be related to the interaction between several physiological oscillators. This study is based on electrocardiogram and respiratory flow data obtained from 3 different subjects during paced breathing at 10 different pacing cycle lengths ranging from 5 s to 12 s. Two different methods ideally suited for the analysis of synchronization pattern of coupled oscillators are applied: 1. Symbolic dynamics based on symbol coding adapted for the detection of respiratory modulation of cardiac parasympathetic activity discloses two regimes of different synchronization behaviour within the frequency area corresponding to the Arnold tongue of 1:1 frequency-locking between respiratory flow and respiratory heartbeat variation (respiratory sinus arrhythmia). 2. The analysis of the phase shift between respiratory flow and respiratory sinus arrhythmia indicates that synchronization is not a static but a dynamic phenomenon. The observed dependence of the phase shift on respiratory cycle length shows large inter-individual variation. These findings turn out to be further hints for the existence of an additional central oscillator in the frequency range of respiration interacting with the central respiratory oscillator driving mechanical respiration.
Der Theorie des gemeinsamen Lerngegenstandes für den integrativen Unterricht folgend, werden Ausführungen zum pädagogischen Leistungsverständnis und zu Möglichkeiten leistungsbezogener Differenzierung zwischen Grundschülern und Schülern im Förderschwerpunkt geistige Entwicklung im gemeinsamen Musikunterricht thematisiert.
Potsdamer Reden
(1998)
Long-term measurements (1979-1994) of meteorological parameters and of algal and crustacean biomass were used in conjunction with a comprehensive hydrodynamic model to evaluate the impact of weather conditions on plankton dynamics in a large, deep, temperate lake (Upper Lake Constance), and to identify potential causal mechanisms. The natural variability of weather conditions, including the exceptionally mild winters during the late eighties, allowed us the investigation of the covariation of meteorological parameters such as irradiance, air temperature, and wind with vernal algal and crustacean population growth. Crustacean zooplankton responded strongly to differences in surface water temperature, but not to mixing depth or algal biomass. Clear relationships between changes of algal biomass and meteorological factors were only found during the rare occasions when acted together to favour or hamper algal development. Otherwise, the impact of meterological conditions on the physical conditions which were most likely conducive to phytoplankton development, could not be followed by this simple approach. This problem was overcome with a one-dimensional hydrodynamic turbulent exchange model driven by the meteorological boundary conditions at the water surface. It was used to simulate the development of the vernal density stratification and to investigate the relationships between meteorological conditions and exchange rates from the euphotic to the aphotic zone. The beginning of the spring algal bloom was shown to depend on the stabilization of the upper part of the water column. As soon as mixing below 20 m was inhibited, confining the algae to the euphotic zone for prolonged periods of time, substantial increases in algal standing stock occurred consistently. In contrast, during periods when high vertical mixing rates were computed with the model no substantial increases of algal biomass were found. This tight coupling between the estimates of vertical mixing intensity and observed algal development, combined with knowledge about the impact of individual meteorological factors on mixing, enabled predictions about the response of algae to different weather conditions during spring.
Variationen der P300- Amplitude bei seqeuntiell zunehmender Belastung des Arbeitsgedächtnisses
(1998)
Der personenzentrierte Ansatz : die pädagogisch-therapeutisch orientierten Spielstunden mit Bernd
(1998)
Editorial
(1998)
Editorial
(1998)
Editorial
(1998)
Musikgeschichte(n)
(1998)
Kurssbuch Referendariat
(1998)
Freiarbeit
(1998)
A case of primary progressive ahasia : a 14year follow-up study with neuropathological findings
(1998)
Compressions and extensions
(1998)
The effects of rotation and stellar magnetic fields on the nebular shapes : LBV nebulae and PNe
(1998)
The Pistol star
(1998)
On the validity of the core-mass luminosity relation for TP-AGB stars with efficient dredge-up
(1998)