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Reactive modifications of the autonomous time structure in the human organism

100%
Hildebrandt G.
Journal of Physiology and Pharmacology
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1991
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tom 42
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nr 1
The spectrum of biological rhythms exhibits characteristic principles of biological time structure which also rule the functional behaviour. With increasing period lengths the rhythms become increasingly complex. In the long-wave section the rhythmic functions find their corresponding cycles in the environment, whereas the shorter waves respresent only endogenous autonomous rhythms, which maintain an internal time order by means of frequency- and phase-coordination. Under resting conditions and in a state of complete adaptation only a few spontaneous rhythms dominate in the spectrum. However, under loading conditions as well as in pathological situations further periodicities come up. The spectrum of rhythms can be divided into certain blocks, with the period lenghts predominating in each of these whole number frequency ratios forming a harmonic system. Frequency- and phase coordination establish a system of co-action which favours the functional economy of the organism. A tripartite organization of the autonomous rhythms involves different functional behaviours with regard to frequency, amplitude, and phase. Slower rhythms act upon the faster rhythms preferably by modulating their frequencies, while changes of the faster rhythms influence the slower ones by enhancing their amplitudes, multiplying their period lengths and shifting their phases. In principle the reactions of living systems are periodically structured. Reactive periodicity brings to appearance an endogenous time structure, which prefers whole number relationships with the spontaneous rhythms. The phase position of reactive periods depends on the stimulus. The amplitudes dampen down with increasing compensation. From the medical point of view so-called circaseptan (about 7 days) reactive periods are of predominant interest. This periodicity can be observed in numerous adaptive and compensating processes. It does not depend on the external week cycle and was already known to the antiquity.
2

Deterministic and noise-induced signal amplification and signal transfer in coupled nonlinear systems

86%
Kaiser F.
Cellular and Molecular Biology Letters
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1999
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tom 04
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nr 1
Nonlinear oscillatory processes are discussed under the influence of external signals to improve the understanding of signal interaction with and within biological systems. The biological endogeneous rhythms are modelled by self-sustained oscillations (limit cycles). Main emphasis is on the combined influence of very slow and very fast stimuli compared to the relevant internal frequencies and on additional effects caused by external and internal noise sources. The models represent arrays of coupled passive and active nonlinear oscillators, an external harmonic signal stimulates the input oscillator (initial stage of signal chain). Signal transfer through the pathway is studied under the influence of noise. Different noise contributions are considered, including spatially-coherent and spatially-incoherent sources. Results reveal a stochastic resonance kind of behaviour at different stages of the signal transfer, the harmonic signal is transduced through the whole system of coupled oscillators. The combined action of different noise exhibits constructive as well as destructive influences on signal amplification. In addition, the influence of noise on the synchronous behaviour of coupled active systems is investigated. Noise-induced synchronization as well as desynchronization of the output signal to the external drive result. Besides signal amplification the systems exhibit the property to decode the frequency encoded information.
3

Circadian and seasonal changes in honeybee (Apis mellifera) worker susceptibility to diazinon, teflubenzuron, pirimicarb, and indoxacarb

58%
Piechowicz B., Grodzicki P., Stawarczyk M., Stawarczyk K.
Polish Journal of Environmental Studies
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2013
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tom 22
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nr 5
Circadian and seasonal changes in the susceptibility of honeybee (Apis mellifera) workers to intoxication by organophosphate, benzoylphenyl urea, carbamate, and oxadiazine insecticides have been studied from 2008 to 2009. Animals were collected in two apiaries located in the surroundings of Mielec and Tarnobrzeg in the Sub-Carpathian Province. The experiments consisted of intoxication by select xenobiotics of the subsequent groups of animals in two-hour intervals for a period of 24 hours and the analysis of their survivability. Experiments were carried out in spring and summer. The results suggest that the susceptibility of bees to different groups of insecticides varies significantly, both in the circadian and seasonal rhythms.
4

The light/dark cycle disruption affects hepatic function both in metabolic parameters and tissue structure in a nocturnal desert rodent: Gerbillus tarabuli

58%
Rouibate A. D., Banhafri N., Ouali-Hassenaoui S., Dekar-Madoui A.
Folia Histochemica et Cytobiologica
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2020
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tom 58
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nr 3
5

Regulation of hydroxyindole-O-methyltransferase gene expression in the pineal gland and retina

58%
Voisin P., Guerlotte J., Bernard M., Greve P., Grechez-Cassiau A., Collin J. P.
Acta Neurobiologiae Experimentalis
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1994
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tom 54
|
nr S
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