摘要:

The electrocardiogram of pigeons was recorded while they pecked an impact transducer under operant control according to a variable ratio schedule. An analysis of the records in terms of crossaverages between heart beats and pecks, the quasi‐equivalents of crosscorrelation functions, revealed that pecks and heart beats tend to coincide temporally at above chance levels according to patterns that vary from individual to individual pigeon. The mechanisms and the functions of the coupling are discussed.

ISSN:0022-1945    

DOI:10.1080/09291018609359917

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The statistical study of environmental cycles has received extensive consideration over the years and a variety of models can be applied to data presumed to contain cycles. However, a search in the current literature and textbooks failed to produce a suitable reference that treats the practical aspects of the subject in a systematic manner. The purpose of this paper is to advance a strategy to investigate cycles which may occur at different levels of data aggregation and on different frequencies in a large, multivariate time series context. The strategy is based on the validity for environmental cycles of certain simplifying assumptions and involves extended formal definitions of temporal partitions, cycles, and related concepts. The motivation was provided by the need to interpret the 1979–1981 stretch of the 198 air pollution time series obtained for the Harvard epidemiological study of the health effects of air pollution, which serves as an example to the strategy suggested.

ISSN:0022-1945    

DOI:10.1080/09291018609359918

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In this study, the day course of blood gastrin was investigated in a group of 15 students whose eating habits had not been synchronized. A significant 24‐h pattern could be found. Because of the discrepancy between the rhythm parameters obtained by Cosinor analysis and the visual inspection of the original data, a new method of testing the suitability of the Cosinor model was applied. On analysis of our data we came to the conclusion that the circadian rhythm of blood gastrin could have an endogenous as well as an exogenous component.

ISSN:0022-1945    

DOI:10.1080/09291018609359919

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Ten adult rabbits were exposed to a LD 12:12 regimen for 18 months. They were initially intact, then deprived of their cervical sympathetic trunks and, finally, also blinded. In each condition experiments were performed, lasting 54 h in darkness, that showed in intact and sympathectomized animals the presence of a programmed rhythm in root‐mean‐square value (σ) of the occipital EEG. Sympathectomy reduced the amplitude of this rhythm by one half, whereas it raised the levels forgof the EEG's and EMG's by some 7% and induced a slight alteration of the EEG spectrum in favour of the frequencies 0.5–4.5 cps. When the optic nerves had been sectioned also, the rhythm was free‐running while the g ‘s of both the EEG and EMG had been further increased by more than 20% and the EEG spectrum had markedly shifted in favour of, again, the lower frequencies. The results point to an important role for the retinal dark discharge and suggest that the latter is modulated by the central circadian system by way of the cervical sympathetic nerves.

ISSN:0022-1945    

DOI:10.1080/09291018609359920

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Activity data from two experimental lizard groups were analysed in order to search for 24 h‐entrained and ultradian periodicities. The data of a first group were obtained through motion sensitive platforms situated under the animals’ cage and continuously for up to 12 consecutive days; those from a second group were collected by manual recording of the behaviour patterns of individual animals for 2 h each dayovera 10‐day period. Lizards from both groups were situated in cages inside isolated chambers in which a light‐dark cycle (12:12), a temperature of 28°C ±1° and a relative humidity of 50–60% were maintained. Periodogram analysis showed the existence of a significant period peak (p < 0.01) at 24 h. Autocorrelation functions and spectral analysis of different data‐segment lengths showed that ultradian periodicities were present in the daily motor activity, appearing as noisy though frequency‐band limited. Differences in the frequency band‐limited fluctuations were found between morning and afternoon activities: during the morning ultradian activity appears distributed in two bands (4.5–36 c/day and 63–94 c/day), the power being mainly concentrated in the second one, while during the afternoon it was in the 4.5–36 c/day band. Results from the second lizard group showed only one band (24–60 c/day) overlapped with the first one from the latter group. Although activity recording methods and some experimental conditions are discussed as possible sources of these differences, the possibility of endogenous ultradian variation within the individuals is also suggested.

ISSN:0022-1945    

DOI:10.1080/09291018609359921

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The spectrum of ultradian rhythms in man consists of three parts. In the long wave section it predominantly includes metabolic functions; in the medium wave section, the rhythmic functions of transport and distribution systems; and in the short wave section, the rhythmic functions of the information system. In addition, the medium wave section comprises the frequency ranges of locomotor, psychomotor and similar task involved as well as musical rhythms, respectively.

ISSN:0022-1945    

DOI:10.1080/09291018609359922

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

During the cell cycles of synchronous cultures of several different yeasts and protozoa, oscillations in the rate of respiration and of total cellular protein content have been demonstrated. Energy supply (from mitochondrial oxidative phosphorlation) and energy demand (biosynthetic reactions, especially protein accumulation) are closely coupled oscillating systems. Phase correspondence between O2consumption rates, intracellular ADP pool size, and total cellular protein indicates that it is energetic demand that determines mitochondrial activity (respiratory controlin vivo). The dynamics of the coupled oscillators indicate that the rate‐determining control circuit operates on a time scale expected of epigenetic reactions (transcription and translation). Thus the energy‐yielding reactions are enslaved to the slower time constants of biosynthesis. Temperature compensation indicates a timing function, and a common phase reference point makes subcycles commensurate with the cell cycle. It is suggested that cell cycle timing, by counting subcycles in growing cells, may become dominated by circadian control in slowly growing natural populations, and that the same subcycles may be used for circadian timekeeping. The discontinuous nature of growth suggests extensive and rapid turnover of macromolecular cell components organised in alternating temporal compartments of biosynthetic and degradative processes.

ISSN:0022-1945    

DOI:10.1080/09291018609359923

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Neonatal treatment with monosodium glutamate (MSG) results in a substantial degeneration of the inner layer of the retina and a decreased diameter of the optic nerves. Nevertheless, MSG‐treated animals entrain and re‐entrain to a light dark cycle. The question arises whether MSG selectively destroys the optic pathways which are involved in vision but not the retinohypothalamic trart that mediates entrainment. In these experiments not only entrainment and re‐entrainment of the circadian food intake rhythm of MSG‐treated rats was investigated but also the freerunning period under continuous bright and dim light It appears that MSG‐treated rats have shorter freerunning periods under continuous illumination than controls. Therefore, these results suggest that also those pathways involved in entrainment of the circadian food intake rhythm are affected by neonatal treatment with MSG.

ISSN:0022-1945    

DOI:10.1080/09291018609359924

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018609359916

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor