Biomedical subjects

E De Valck

Publications and source records attributed to E De Valck.

4 recordsLinked to original sources

PubMed2003

Sleepiness as a state-trait phenomenon, comprising both a sleep drive and a wake drive.

In this paper it is proposed to extend the classical models of sleepiness in two ways. Firstly, the role of a wake drive, besides a sleep drive, in determining sleepiness is emphasised. Although this has already been suggested in literature and convincing arguments can be found, it is not generally accepted. Secondly, we argue to incorporate trait aspects of sleepiness or a long-term person-specific level of sleepiness, besides short-term changes of sleepiness or 'state-sleepiness'. Shortly, a conceptualisation of sleepiness in which situational wake drive and sleep drive modify a basal level of both wake drive and sleep drive, is proposed. It implies that sleepiness can result from essentially different factors involved: a chronic condition or an acute state of either a high level of sleep drive, a low level of arousal or a combination of both. This is illustrated in a working model and potential assessment tools for the wake drive and state versus trait sleepiness are discussed.

Humans↗

PubMed2001

Slow-release caffeine as a countermeasure to driver sleepiness induced by partial sleep deprivation.

The effect of partial sleep deprivation (PSD) on driving abilities, as measured with a driving simulator, and the value of slow-release caffeine as a countermeasure to the expected performance decrements, were studied. Twelve subjects, between 20 and 25 years of age, underwent four experimental conditions, 4.5 or 7.5 h time in bed (TIB) with 300 mg slow-release caffeine or placebo, according to a Latin square design. Driving performance was measured twice by a 45-min driving task on a simulator. Subjective sleepiness/alertness and mood were assessed four times, by means of the Stanford Sleepiness Scale (SSS) and Profile of Mood States (POMS). After 4.5 h as compared with 7.5 h TIB lane drifting and speed deviation were higher, but only the effect on the first variable reached significance. In the placebo condition at 13.00 h, accident liability increased after PSD. Subjective sleepiness was higher in the 4.5 h TIB group. Caffeine intake gave rise to a decrease in lane drifting and after PSD it led to a smaller speed deviation and accident liability. The findings suggest that a lack of sleep can lead to a significant driving performance impairment, with drivers having problems to maintain an appropriate road position and a posted speed and more drivers getting involved in an accident. Secondly, the results indicate that caffeine - more specifically slow-release caffeine - can serve as a valuable countermeasure to these performance decrements, in the absence of any important side-effects, especially when its application is of an acute nature and when there is no opportunity to take a nap.

Adult↗

PubMed1996

[Use of the computer in dentistry: video superimposition and facial reproduction using the expedience of the computer interface].

Both video superimposition and computer facial reproduction play a useful role in the process of identification, particularly in the early stages of an investigation or when other more definitive methods may not be available. Video superimposition combined with a computer overlay technique can be used to establish whether a skull outline matches an image of a missing person, being a photograph, slide or videoimage. A computer driven robot can be used to simplify the alignment of the skull with the position of the head on the image. Craniofacial or facial reproduction are used in both 2D or 3D to produce an image which can be used for identification purposes.

Computer Graphics↗

PubMed1995

[Bite mark analysis. Part 1. Methods and overview].

Criminal cases in which a suspect or a victim has left his or her teeth marks on another person or on an inanimate object such as a candy bar, an apple, cheese or even a beer can seem to occur more frequently. Testifying to the similarity or dissimilarity of a suspect's dentition to the bite mark in question is probably the most unique contribution that forensic dentistry makes to the judicial inquiry. This is a grave responsibility because a defendant's life or freedom may depend on the testimony given by the forensic odontologist in court.

Bites, Human↗