摘要:

Daily torpor in P.leucopusis an endogenous circadian rhythm which employs photoperiod as a zeitgeber. Mice maintained under constant darkness exhibited a free‐running rhythm with a period of 23.52 h. Entrainment of this free‐running rhythm occurred when a LD = 9:15 photoperiod was provided.

ISSN:0022-1945    

DOI:10.1080/09291018009359691

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The circadian levels of norepinephrine and serotonin in the caudate nucleus, cerebellum, cortex and midbrain were simultaneously determined fluoro‐metrically every three’ hours in control rats and in rats pretreated intraperi‐toneally with sublethal doses of phenobarbital sodium. All animals were adapted for minimum period of three weeks in an environmental room equipped with an automatically‐timed photoperiod lasting from 08:00 to 20:00 h daily. The results‐of this experiment show that the levels of norepinephrine and serotonin in all the brain areas studied vary diurnally. Phenobarbital sodium pretreatment alters the levels and/or phase‐shifts the circadian pattern of these biogenic amines.

ISSN:0022-1945    

DOI:10.1080/09291018009359692

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Using various staining techniques and methods, the following cells were differentiated from pars distalis of the pituitary gland in the mouse: corticotropic, somatotropic, lactotropic, thyrotropic and gonadotropic cells.

ISSN:0022-1945    

DOI:10.1080/09291018009359693

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

In order to investigate the role of a circadian clock in the timing of a monthly rhythm, different populations of planarians were maintained in constant darkness or, to manipulate the period of a circadian rhythm, in light‐dark cycles totalling 20 h, 24 h, or 28 h. The orientation response of the planarians was followed for 2 months. If solar‐ and lunar‐day rhythms were interacting to produce a monthly oscillation in the orientation response, the interval between “monthly”; peaks would be predictably altered. However, no difference in the phase or period of the monthly rhythm was observed among the experimental groups.

ISSN:0022-1945    

DOI:10.1080/09291018009359694

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Spotted munia exhibits a distinct annual periodicity in body weight, which does not coincide with the annual temperature and photoperiodic changes. A seasonal variation in daily feeding pattern could be associated with the cycle. An endogenous circannual oscillator with a periodicity of about 10 months may also be involved. This bird, therefore, may prove to be a suitable model for the studies of interaction of daily and annual events with respect to circannual rhythms.

ISSN:0022-1945    

DOI:10.1080/09291018009359695

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The daily variation of body temperature of the North American opossum,Didelphis virginiana,was examined by means of radiotelemetry, and the data were statistically evaluated by a Fourier periodic regression analysis. Four opossums were individually housed at 21°C and two of these opossums were also housed at 7°C ambient temperature. Throughout the investigation the light cycle was LD 9:15 (08:30‐ 17:30h), and body temperatures were recorded each half hour. A prominent 24 h rhythm was observed for the body temperatures of all opossums; for each regression analysis the 24 h harmonic was statistically significant and was the largest portion of the trend. A visual inspection of the fitted curves revealed single peaks and troughs throughout the 24 h period. It is concluded that the opossum exhibits a 24 h rhythm of body temperature comparable to other metatherians.

ISSN:0022-1945    

DOI:10.1080/09291018009359696

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Extant methods for identifying longer‐term cycles in economic and social time series are in various ways limited. Spectral analysis assumes stationarity of variance and reasonably consistent periodicity, while moving average methods are susceptible to judgmental bias and other artifacts. This paper explores the use of stepwise polynomial regression analysis as a method for deciding, on statistical grounds, whether a longer‐term cycle exists; and for characterizing its specific form. Used with U.S. economic and social data, the polynomial regression analysis provides evidence for the existence of two longer‐terms values corresponding to the Juglar cycle and the Kuznets cycle; no evidence for a “long wave”; Kondratieff cycle is found. The cross‐series findings also suggest that variations in war and war preparedness play a role in generating such cyclic effects.

ISSN:0022-1945    

DOI:10.1080/09291018009359697

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018009359690

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor