Sleep is regulated by complex biological systems and environmental influences, neither of which is fully clarified. This study demonstrates differential effects of partial sleep deprivation (SD) on sleep architecture and psychomotor vigilance task (PVT) performance using two different protocols (sequentially) that each restricted daily sleep to 3 hours in healthy adult men. The protocols differed only in the period of sleep restriction; in one, sleep was restricted to a 3-hour block from 12:00 AM to 3:00 AM, and in the other, sleep was restricted to a block from 3:00 AM to 6:00 AM. Subjects in the earlier sleep restriction period showed a significantly lower percentage of rapid-eye-movement (REM) sleep after 4 days (17.0 vs. 25.7 %) and a longer latency to the onset of REM sleep (L-REM) after 1 day (78.8 vs. 45.5 min) than they did in the later sleep restriction period. Reaction times on PVT performance were also better (i.e. shorter) in the earlier SR period on day 4 (249.8 vs. 272 ms). These data support the view that earlier-night sleep may be more beneficial for daytime vigilance than later-night sleep. The study also showed that cumulative declines in daytime vigilance resulted from loss of total sleep time, rather than from specific stages, and underscored the reversibility of SR effects with greater amounts of sleep., H. Wu ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
We analyzed human postural responses to muscle vibration applied at four different frequencies to lower leg muscles, the lateral gastrocnemius (GA) or tibialis anterior (TA) muscles. The muscle vibrations induced changes in postural orientation characterized by the center of pressure (CoP) on the force platform surface on which the subjects were standing. Unilateral vibratory stimulation of TA induced body leaning forward and in the direction of the stimulated leg. Unilateral vibration of GA muscles induced body tilting backwards and in the opposite direction of the stimulated leg. The time course of postural responses was similar and started within 1 s after the onset of vibration by a gradual body tilt. When a new slope of the body position was reached, oscillations of body alignment occurred. When the vibrations were discontinued, this was followed by rapid recovery of the initial body position. The relationship between the magnitude of the postural response and frequency of vibration differed between TA and GA. While the magnitude of postural responses to TA vibration increased approximately linearly in the 60-100 Hz range of vibration frequency, the magnitude of response to GA vibration increased linearly only at lower frequencies of 40-60 Hz. The direction of body tilt induced by muscle vibration did not depend on the vibration frequency., A. Polónyová, F. Hlavačka., and Obsahuje bibliografii
The South Korean film industry represents a masculine-privileged gender regime that over the last few decades has shown a newfound strength both at home and abroad. However, challenging this masculine privilege are a growing number of important though unheralded female writers-directors operating in both the independent and commercial sectors of the industry. In this article, the authors present a case study that explores the work of five of these female writers-directors within this context. They begin by asking two key questions: can female writers-directors find a voice within the Korean film industry that challenges the traditional gender stereotypes both within the industry and in the wider Korean culture? How can the Korean experience connect to the Western experience? The first methodological step in explicating the case study is to set out a particularly Western theoretical approach that emphasises the idea that masculine privilege exists hegemonically within the so-called ‘hegemony of men’. The authors then go on to highlight specific elements in the work of these female writers-directors that expose aspects of both challenge and constraint within the hegemony of men. They conclude that, although the work of these female writers-directors indeed challenges tradition and gendered stereotypes sustained within the hegemony of men, such challenges represent moments of reformism rather than revolutionary systematic change., Richard Howson, Brian Yecies., and Obsahuje bibliografii