The device records the time of dusk and dawn every day, and from that calculates day length, which can be used to determine latitude (the length of a given day varying with north-south location).
By comparing the time of dusk and dawn to the time at the starting point, the device can also log longitude, just as sea explorers once tracked how far east or west they had traveled from the prime meridian at Greenwich, England, by carrying a clock set to Greenwich time and comparing it with the local time.
This may occur because the current model lacks the regulatory events that are likely to accompany the light-dark transition, so the only deficiency of the model is located around the time of dusk.
In light-response plots such as those shown in Figures 4A and 5A, these values correspond to ϕ lying parallel to the lines indicating the times of dusk and dawn respectively.
Mathews' sun arc hypothesis (Baker, 1978) recognized that latitudinal information from the sun's arc, and longitudinal information from the time of dawn, dusk or zenith, when compared with the time of these events at home, could provide an animal with an approximate position on the Earth's surface, a fact long exploited by mariners in possession of ephemeris data, a sextant and a chronometer.
There is a lighted candle (indicating that the time of day is dusk), a metronome (indicating time itself), and two earlier Matisses: a small sculpture of a sensual odalisque and a large image from a painting of a stern-seeming woman seated on a high stool, floating free on the gray wall.
This was remedied by changing the time of day from dusk to night, adding rain and other weather effects, and using camera movement to simulate rough waters.
In addition, limiting the impact of light on the SCN would be useful in nonequatorial latitudes during the equinoxes when the time of dawn and dusk, along with activity and food availability, moves very rapidly.
LightsOut - Set time of day to dusk.
Therefore, even the larvae that are very close to pupariation are able to rapidly switch for diapause if the photoperiod "seems to signal for it" (responding already to a phase shift of dusk time or to the first long night).
The given Zt's were selected on purpose, first, in order to take into account potential effect of diurnal fluctuations, which we know is generally very small based on the results of our parallel study (Koštál and Schöttner, unpublished results), and second, to allow comparing the transcriptomic responses to switch OFF the light (phase shift of dusk time).
