Effects of Time of Day and Sleep Deprivation on Motorcycle-Driving Performance

The aim of this study was to investigate whether motorcycle handling capabilities – measured by means of the efficiency of emergency manoeuvres – were dependent on prior sleep deprivation and time of day. Twelve male participants voluntarily took part in four test sessions, starting at 6 a.m., 10 a.m., 2 p.m., and 6 p.m., following a night either with or without sleep. Each test session comprised temperature and sleepiness measurements, before three different types of motorcycling tests were initiated: (1) stability in straight ahead riding at low speed (in “slow motion” mode and in “brakes and clutch” mode), (2) emergency braking and (3) crash avoidance tasks performed at 20 kph and 40 kph. The results indicate that motorcycle control at low speed depends on time of day, with an improvement in performance throughout the day. Emergency braking performance is affected at both speeds by time of day, with poorer performance (longer total stopping distance, reaction time and braking distance) in the morning, and also by sleep deprivation, from measurements obtained at 40 kph (incorrect initial speed). Except for a tendency observed after the sleepless night to deviate from the initial speed, it seems that crash avoidance capabilities are quite unaffected by the two disturbance factors. Consequently, some motorcycle handling capabilities (stability at low speed and emergency braking) change in the same way as the diurnal fluctuation observed in body temperature and sleepiness, whereas for others (crash avoidance) the participants were able to maintain their initial performance level despite the high levels of sleepiness recorded after a sleepless night. Motorcycle riders have to be aware that their handling capabilities are limited in the early morning and/or after sleep deprivation. Both these situations can increase the risk of falls and of being involved in a road accident

Room temperature polar structure and multiferroicity in BaFe2Se3

International audienceThe understanding of the superconducting phase under pressure in the famous iron-based spin ladder BaFe2Se3 commands a perfect understanding of the structural properties. We present an accurate single crystal x-ray analysis which demonstrates that the structure admitted until now at room temperature is totally ruled out. We show that the system has a polar structure already at 300 K and is thus ferroelectric. Its structure is modified below the Néel transition and the polarization is intensified. These features unambiguously prove the multiferroic character of BaFe2Se3 as proposed theoretically. This system evidences a competition between multiferroicity and superconductivity

Low thoracic skeletal muscle index is associated with negative outcomes in 244 patients with respiratory COVID-19

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