Presence-absence cycles of the mother and not light-darkness are the zeitgeber for the circadian rhythm of newborn mice

The relative roles of conflicting zeitgebers [presence/absence (PA) cycles versus light/dark (LD) cycles] on entrainment of circadian rhythm of locomotor activity were tested in pups of the night active mouse Mus booduga. During the early days of the pups' life the PA cycles of the mother acted as a zeitgeber and entrained their activity rhythm, even though the LD cycles were available. Entrainment by LD cycles took place only when the pups' eyes opened and probably became functional.     

Seasonal prediction of European cereal prices: good forecasts using bad models?

Because of their natural adherence to the climate and pronounced seasonal cycles, prices of field crops constitute an interesting field for exploring seasonal time series models. We consider quarterly prices of two major cereals: barley and wheat. Using traditional in‐sample fit and moving‐window techniques, we investigate whether seasonality is deterministic or unit‐root stochastic and whether seasonal cycles have converged over time. We find that seasonal cycles in the data are mainly deterministic and that evidence on common cycles across countries differs for the two commodities. Out‐of‐sample prediction experiments, however, yield a ranking with respect to accuracy that does not match the statistical in‐sample evidence. Parametric bootstrap experiments establish that the observed mismatch is indeed an inherent and systematic feature. Copyright © 2008 John Wiley & Sons, Ltd.     

Suppression of annual plasma testosterone and thyroxine cycles in the edible dormouseGlis glis under constant photoperiod at 24°C

Summary Exposure of male ebible dormice all year round to an unwarying photoperiod and warm temperature disrupted their biological cycles; hibernation was almost completely suppressed, and short lived infradian cycles of body weight, and of plasma testosterone and thyroxine were measured instead of the normal annual patten.     

Influence of photoinduction on aminotransferase activity in biloxi soybean, Glycine max. L., Merr

Increasing number of photoinductive cycles markedly influenced the activity of 5 different aminotransferase systems as compared to non-inductive cycles. The activity was related to the requirement of the corresponding aminoacid synthesised during the process of photoinduction in the leaves.     

Influence of photoinduction on aminotransferase activity in biloxi soybean,Glycine max., L., Merr.

Summary Increasing number of photoinductive cycles markedly influenced the activity of 5 different aminotransferase systems as compared to non-inductive cycles. The activity was related to the requirement of the corresponding aminoacid synthesised during the process of photoinduction in the leaves.     

Communication and synchronized molting in a colonial araneid spider,Eriophora bistriata

Summary The colonial orb-weaving spider,Eriophora bistriata, coordinates molting cycles through communication. Colonies with differing molting cycles synchronize when combined. Intercycle intervals depend upon food availability. The possible coordination of this synchrony by chemical communication among spiders is discussed.     

Circadian pacemaker does not arrest in deep hibernation. Evidence for desynchronization from the light cycle

A freerunning rhythm of locomotor activity was observed between hibernation bouts in Turkish hamsters (mesocricetus brandti) kept in 10L:14D light-dark cycles at 10 +/- 1 degree C. The data further indicate an influence of natural hypothermia upon the circadian system and its ability to entrain to light-dark cycles.     

The pineal and melatonin: regulators of circadian function in lower vertebrates

The pineal has been identified as a major circadian pacemaker within the circadian system of a number of lower vertebrates although other pacemaking sites have been implicated as well. The rhythmic synthesis and secretion of the pineal hormone, melatonin, is suggested as the mechanism by which the pineal controls circadian oscillators located elsewhere. Both light and temperature cycles can entrain the pineal melatonin rhythm. The pineal, therefore, acts as a photo and thermoendocrine transducer which functions to synchronize internal cycle with cycles in the environment. A model is presented which portrays the pineal as a major component of a 'multioscillator' circadian system and which suggests how these multiple circadian clocks are coupled to each other and to cycles of light and temperature in the external world.     

Improved business planning through an awareness of political cycles

Can business planning be improved if more attention is paid to underlying political cycles? This paper compares practitioner and researcher perspectives on this issue. While practioners stand to gain useful insights from a careful examination of past political cycles, these insights may be disconfirmed by rigorous tests carried out by researchers. In this paper we isolate and examine five hypotheses from the literature on the political-economic cycle.     

Involvement of the circadian system in photoperiodic control of pubertal development in female deer mice, Peromyscus maniculatus

Pubertal development in female deer mice, Peromyscus maniculatus, was stimulated by exposure to light cycles of LD 16:8, LD 6:30 or LD 6:54, but not by exposure to cycles of LD 6:18 or LD 6:42. These results support the hypothesis that female deer mice use a circadian rhythm of responsiveness to light to measure photoperiodic time.     

Circadian pacemaker does not arrest in deep hibernation. Evidence for desynchronization from the light cycle

Summary A freerunning rhythm of locomotor activity was observed between hibernation bouts in Turkish hamsters (Mesocricetus brandti) kept in 10L:14D light-dark cycles at 10±1°C. The data further indicate an influence of natural hypothermia upon the circadian system and its ability to entrain to light-dark cycles.     

Synchronization of deposition of daily growth layers in the cuticle of the cockroachBlaberus fuscus by gating of moult

Summary InBlaberus fuscus, combined light/dark-warm/cold cycles induce a rhythm of moulting. Most of the moults take place in the middle of the dark cold phases. Because of a stable phase-relation between moulting time and endocuticle growth rhythm, the latter is synchronized with the environmental cycles, too; lamellated layers are deposited during the light warm phases, which correspond to the time of resting of the cockroaches. Therefore, the cuticle growth is internally synchronized with rhythmic locomotory activity and metabolic rhythms.     

The pineal and melatonin: Regulators of circadian function in lower vertebrates

Summary The pineal has been identified as a major circadian pacemaker within the circadian system of a number of lower vertebrates although other pacemaking sites have been implicated as well. The rhythmic synthesis and secretion of the pineal hormone, melatonin, is suggested as the mechanism by which the pineal controls circadian oscillators located elsewhere. Both light and temperature cycles can entrain the pineal melatonin rhythm. The pineal, therefore, acts as a photo and thermoendocrine transducer which functions to synchronize internal cycle with cycles in the environment. A model is presented which portrays the pineal as a major component of a multioscillator circadian system and which suggests how these multiple circadian clocks are coupled to each other and to cycles of light and temperature in the external world.     

The pineal and melatonin: Regulators of circadian function in lower vertebrates

Summary The pineal has been identified as a major circadian pacemaker within the circadian system of a number of lower vertebrates although other pacemaking sites have been implicated as well. The rhythmic synthesis and secretion of the pineal hormone, melatonin, is suggested as the mechanism by which the pineal controls circadian oscillators located elsewhere. Both light and temperature cycles can entrain the pineal melatonin rhythm. The pineal, therefore, acts as a photo and thermoendocrine transducer which functions to synchronize internal cycle with cycles in the environment. A model is presented which portrays the pineal as a major component of a multioscillator circadian system and which suggests how these multiple circadian clocks are coupled to each other and to cycles of light and temperature in the external world.     

Predicting Recessions with Factor Linear Dynamic Harmonic Regressions

We propose a new framework for building composite leading indicators for the Spanish economy using monthly targeted predictors and small‐scale dynamic factor models. Our leading indicator index, based on the low‐frequency components of four monthly economic variables, is able to predict the onset of the Spanish recessions as well as the gross domestic product (GDP) growth cycles and classical industrial production cycles, both historically and in real time. Also, our leading indicator provides substantial aid in forecasting annual and quarterly GDP growth rates. Using only real data available at the beginning of each forecast period, our indicator one‐step‐ahead forecasts shows substantial improvements over other alternatives. Copyright © 2013 John Wiley & Sons, Ltd.     

International interdependence of business cycles in the manufacturing industry: The use of leading indicators for forecasting and analysis

This article introduces new leading indicators for fifteen industrialized countries which enable the business cycle in manufacturing to be forecast fairly reliably between 4 and 6 months ahead. These indicators are based on an improved variant of the NBER method, yielding a composite leading indicator characterized by less erratic movements and clear turning points. The indicators are used to explore the international interdependence of business cycles and to examine the degree to which this interdependence is affected by growing economic integration, as in the EC. For each of the countries studied, the various foreign economies affecting the local business climate are identified. Since the business cycles of some countries clearly lead those of others, this international interdependence can be used to further improve the predictive power of the leading indicators in the lagging countries.     

Electrical colonic activity in the conscious dog]

Identification of two distinct rhythms of the colonic slow waves at a mean frequency of 5 and 18 cycles/min. Evidence is provided for an origin of the faster rhythm from the mascularis mucosae.     

Crowding during pregnancy delays puberty and alters estrous cycles of female offspring in mice

Chronic crowding of mice during late pregnancy resulted in offspring of lowered birthweights and, in the females, delayed puberty and altered estrous cycles. Plasma corticosterone in the crowded dams was elevated acutely, lending some support to the hypothesis of adrenocortical mediation of prenatal stress effects.     

Prenatal stress and postnatal androgen: Effects on reproduction in female rats

Summary Heat-restraint stress applied to pregnant rats during the last trimester disrupts oestrus cycles in female offspring and alters adrenal, ovarian and uterine weights at autopsy. Sexual receptivity is left intact. Prenatal stress may operate by increasing exposure of fetal females to androgens in utero.