Although homeostatic mechanisms remain of utmost importance, rhythmic changes are present also. The main ones have a period of 24 h (circadian) or about 2-3 h (ultradian). Circadian rhythms are derived from a body clock, found in the base of the brain, and from the pattern of our sleep wake cycle, including activity and meal times. These rhythms promote the regular changes between an active wak...

This paper describes a lithography-based microfabrication process developed for a recuperative heat exchanger intended for use in a cryosurgical probe. The probe, which uses the Joule-Thomson (JT) cooling cycle, must achieve a temperature < -50°C, with a freeze rate of 25-50°C/min. The heat exchanger must maintain high stream-to-stream thermal conductance while restricting parasitic stream-wise...

STUDY OBJECTIVES The purposes of this study were to compare the benefits of different length naps relative to no nap and to analyze the electroencephalographic elements that may account for the benefits. DESIGN A repeated-measures design included 5 experimental conditions: a no-nap control and naps of precisely 5, 10, 20, and 30 minutes of sleep. SETTING Nocturnal sleep restricted to about ...

the synthesis, spectroscopy and magnetic characterization of five new dinuclear copper(ii) complexes are described. all five compounds have the general formula [cu2(l)4(o-r)2](cl)2 or [cu2(l)2(cl)2](cl)2, in which r = ch3 or h, l=2, 3 or 4-pyridinemethanol as l2, l3 or l4, respectively. the title compounds consist of dinuclear units with bridging methoxo groups in [cu2(l4)4(o-ch3)2](cl)2, hydro...

objective: electroencephalogram is a reliable reflection of many physiological factors modulating the brain. the bispectrum is very useful for analyzing non-gaussian signals such as eeg, and detecting the quadratic phase coupling between distinct frequency components in eeg signals.the main aim of this study was to test the existence of nonlinear phase coupling within the eeg signals in a certa...

GLOBAL TRENDS OF INCREASED WORK, DOMESTIC AND SOCIAL DEMANDS, AND ASSOCIATED NOCTURNAL SLEEP REDUCTION AND DAYTIME SLEEPINESS HAVE stimulated research interest into countermeasures of this daytime sleepiness. One countermeasure that has received attention in recent years is brief napping. Naps as brief as 19.8,1 10.8,2 10.2,3 10,4,5 and 9.1 minutes6 have been shown to improve alertness and perf...