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Recent evidence suggests that underlying patterns of cortical activation may partially account for individual differences in susceptibility to the effects of sleep deprivation. Here, functional magnetic resonance imaging (fMRI) was used to examine the activation of military pilots whose sleep-deprivation vulnerability previously was quantified. A Sternberg(More)
OBJECTIVE This study examined the effects of posture on electroencephalographic (EEG) activity and psychomotor vigilance task (PVT) performance in 16 sleep-deprived volunteers. METHODS EEG data were collected while participants completed 10 min PVTs under two counterbalanced sitting/standing conditions during 28 h of continuous wakefulness. RESULTS In(More)
Laboratory research has revealed considerable systematic variability in the degree to which individuals' alertness and performance are affected by sleep deprivation. However, little is known about whether or not different populations exhibit similar levels of individual variability. In the present study, we examined individual variability in performance(More)
Individual differences in cognitive functioning during extended work hours and shift work are of considerable magnitude, and observed both in the laboratory and in the workplace. These individual differences have a biological basis in trait-like, differential vulnerability to fatigue from sleep loss and circadian misalignment. Trait-like vulnerability is(More)
The languages of current dynamic constraint detection techniques are often specified by fixed grammars of universal properties. These properties may not be sufficient to express more subtle facts that describe the essential behavior of a given program. In an effort to make the dynamically recovered specification more expressive and program-specific we(More)
We have extended Wand's type reconstruction algorithm to polymorphic let by extending the constraint language and by using a multi-phase unification algorithm in the constraint solving phase. We show the correctness of our approach by extending the Wand's sound-ness and completeness results. We have validated our approach against other popular type(More)
The most general unifier (MGU) of a pair of terms can be specified by four axioms. In this paper we generalize the standard presentation of the axioms to specify the MGU of a list of equational constraints and we formally verify that the unification algorithm satisfies the axioms. Our constraints are equalities between terms in a language of simple types.(More)
In the constructive setting, membership predicates over recursive types are inhabited by terms indexing the elements that satisfy the criteria for membership. In this paper, we motivate and explore this idea in the concrete setting of lists and trees. We show that the inhabitants of membership predicates are precisely the inhabitants of a generic shape(More)