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Recent mathematical results for the noisy Kuramoto model on a 2-community network may explain some phenomena observed in the functioning of the suprachiasmatic nucleus (SCN). Specifically, these findings might explain the types of transitions to a state of the SCN in which 2 components are dissociated in phase, for example, in phase splitting. In contrast to previous studies, which required additional time-delayed coupling or large variation in the coupling strengths and other variations in the 2-community model to exhibit the phase-split state, this model requires only the 2-community structure of the SCN to be present. Our model shows that a change in the communication strengths within and between the communities due to external conditions, which changes the excitation-inhibition (E/I) balance of the SCN, may result in the SCN entering an unstable state. With this altered E/I balance, the SCN would try to find a new stable state, which might in some circumstances be the split state. This shows that the 2-community noisy Kuramoto model can help understand the mechanisms of the SCN and explain differences in behavior based on actual E/I balance.

Improved housing for laying hens may start from the translation of their behavioral needs into welfare-based design parameters for laying hen houses. The objective of our research was to gain insights into the facility usage and behavioral needs of the hen over 24 h when there are no obvious restraints. Twenty ISA Brown commercial laying hens (Gallus domesticus) that were 18 wk old and not beak trimmed, were accommodated in a pen (4 x 6 m) at 19 + 2 degrees C on a light-dark cycle of 10L:14D. The pen providing nest boxes, drinkers, feeders, perches, sand, and wood shaving was designed to accommodate the hens for the experimental period. Video recordings were made for 10 d. Behavioral analyses were conducted on 5 birds for 5 d. Time spent on each behavior, log survivor analysis of events and inter-event intervals, bout analysis, diurnal pattern in events and bouts, occurrence of behavior in different segments and the corridor of the pen, and sequence analysis were performed to gain insights into the temporal and sequential structures of behavior. Hens spent 97% of the day on nest use, preening, drinking, feeding, still, walking, perching, and resting; 43% on commodity-dependent behavior; and 57% not on commodity-oriented behaviors. Behavioral events were short (around 70% event2 min) and frequent (around 70% inter-event intervals40s). The pen corridor was the preferred place for attack, escape, flying, resting, walking, and wing flapping. Feeding-drinking-feeding, preening-resting-preening, scratching-resting-scratching, dust bathing-resting-preening, or dust bathing-resting-wing stretching-dust bathing were the preferred sequences of behavior. Although hens interrupted ongoing behaviors and changed behaviors frequently, they nonetheless clustered behavioral events.

The objective is to show that it is possible to estimate facility demand of laying hens with discrete-event modelling. This is a step in the development of a tool to estimate the required facility capacity in different housing environments. We explored the possibility to model results from behavioural observations with a discrete-event simulation model. Video recordings were made of eight hens housed in a pen with ample facilities. For the first dataset we observed hens individually during 2 days using continuous focal sampling. From these data we calculated input parameters: probability density functions of durations of behaviours and a transition matrix. Verification, with data from the same dataset, showed that it was possible to simulate facility demand. For a second dataset we observed the hens simultaneously during 5 days using instantaneous scan sampling, yielding data on facility utilisation only. Validation with these data showed that, in general, the model results were comparable. Including group behaviour in future models, however, could improve the prediction. In conclusion, discrete-event modelling is a potential tool to estimate facility demand of laying hens.