摘要:

The use of auto‐regressive modelling for the analysis of circadian and related rhythms is presented as an alternative to the Gosinor, periodogram and auto‐correlation methods. The method is particularly well suited to short time‐series corrupted with non‐white noise and containing multiple rhythm frequencies. Estimation of the model coefficients is via a direct least‐squares algorithm and the frequencies are determined by standard factorisation of the resulting polynomial. Results on simulated data and rat locomotor activity show the feasibility of the method, and indicate how the parameters of model order and sampling rate can be selected to obtain optimum frequency resolution and bandwidth. The method can be implemented using recursive algorithms which avoid matrix inversion and give faster computation, and extension to Maximum Entropy methods is under current investigation.

ISSN:0022-1945    

DOI:10.1080/09291017909359649

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

In yeast cells the dependence of amplitude and period of NADH oscillations on growth phase, starvation time and concentration of hexose fermented (D‐glucose of D‐fructose) has been studied. With both sugars sustained NADH oscillations could be induced during the first logarithmic growth phase only within a small range of starvation time (0.5 to 1.7 h). After transition to diauxic growth on ethanol, oscillations were obtained with D‐glucose from 0.5 to 6 h starvation time, whereas D‐fructose could induce oscillations only after 2 h of starvation. With D‐fructose instead of D‐glucose differences in period lengths of NADH oscillations resulted. These differences after D‐fructose feeding were always consistent and did not depend on the growth phase of the yeast culture. Amplitude and period lengths generally depended on starvation, resulting in stable period lengths after 3 h starvation whereas amplitudes stabilized after 5.3 h. With 0 to 50 mM hexose typical saturation kinetics resulted in amplitude and period of NADH oscillations. With D‐glucose (50 to 500 mM) amplitude and period stayed constant, whereas D‐fructose strongly quenched the oscillations in the same concentration range. It is concluded from these results that comparisons of NADH oscillations induced with D‐glucose or D‐fructose are only meaningful under constant conditions which are: harvesting of yeast culture at the end of the first logarithmic growdi phase, starvation for 5 hours, and 50 mM final hexose concentration. Under these conditions, it can be clearly shown that differences in amplitude and period of NADH oscillations are caused in D‐fructose metabolism.

ISSN:0022-1945    

DOI:10.1080/09291017909359650

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Wheel‐running activity of ten red squirrels,Tamiasciurus hudsonicus, was monitored to determine how temperature and light‐dark cycles affect (1) the number of days required for entrainment; and (2) the phasing, amount and form of wheel‐running activity. The squirrels were individually housed at either a constant temperature of 20 ± 4°C or a temperature cycle of 6.5 ± 2 to 35 ± 2°C. A 12: 12 (207: 0 lx) light‐dark cycle was supplied by an incandescent bulb.

ISSN:0022-1945    

DOI:10.1080/09291017909359651

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The ultrasonically detected daily activity of 10 male and 10 female eastern chipmunks was measured before, during, and after two days of food and water deprivation. Under ad libitum ingestion conditions, eastern chipmunks were not found to be strongly diurnal with only 60% of their total activity occurring in the light Food and water deprivation altered total daily activity as well as the circadian patterning of activity.

ISSN:0022-1945    

DOI:10.1080/09291017909359652

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Caryometric measurements in tanycytes of the median eminence (ME) in sexually mature male and femaleRana temporariacaptured in their natural habitat showed distinct annual fluctuations of nuclear volume.

ISSN:0022-1945    

DOI:10.1080/09291017909359653

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The relationship between left and right circadian oscillations in the ERG of the crayfishProcambarus bouvierihave been studied in intact animals and in animals with cerebral ganglion damage. Except in split‐brain preparations, the ERG oscillations of both sides were always in phase. Surgical bisection of the cerebral ganglion, also results in a shortening of the period length; this suggests that ERG circadian pacemakers normally receive a bilateral input of light stimulation. The neural connections between the eyestalks at the protocerebrum seem to have the most important role in the synchronization of the ERG oscillations of both sides.

ISSN:0022-1945    

DOI:10.1080/09291017909359654

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291017909359648

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor