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Biomedical subjects

C Lamontagne

Publications and source records attributed to C Lamontagne.

10 recordsLinked to original sources
PubMed2002

Sigma smooth pursuit eye tracking: constant k values revisited.

Effective sigma tracking, i.e., apparent movement perception when slow eye movements are made across a stationary repetitive pattern under stroboscopic illumination, has been shown to be a function of the distance between sequential stimuli (P(s)) and the flash frequency (f(s)). The relationship between these factors and eye velocity ( V (e)) has been formally specified as V (e)= k P(s)f(s)[deg s(-1)], where it has been argued that the value of k, which defines the rate limit for eye velocity, is normally 1, or exceptionally 2 or 3. However, theoretically the limitations on the maximum value for k are the maximum optimal pursuit speed for eye tracking (V(max)) and the minimum values which P(s) and f(s) can assume while preserving target discrimination, and since the values for V(max) are known to lie well beyond 20 deg/s and those for P(s) and f s) well below 0.3 deg and 10 Hz respectively, it should be possible to demonstrate empirically that k can assume integer values considerably larger than the indicated maximum of 3. To test this prediction, three subjects performed seven series of five EOG-monitored trials producing sigma-pursuit, with values of k ranging from 1 to 7. All subjects evidenced smooth pursuit eye tracking for every condition and reported experiencing sigma-type apparent motion in 95% of the trials. The results confirm theoretical expectations and unequivocally demonstrate that sigma tracking can be readily effected under conditions where k significantly exceeds the maximal values previously reported, in conformity with theory.

Adolescent↗
PubMed2001

[The development of ethics. Identifying what training in medical ethics is needed by family physicians].

OBJECTIVE: To identify what training in medical ethics physician teachers need. DESIGN: Qualitative research study using a modified nominal group technique. SETTING: Family practice units affiliated with the Department of Family Medicine at Laval University in Quebec. PARTICIPANTS: Fifty-three physician teachers in six family practice units. METHOD: During seven meetings, the teachers shared information on clinical situations that had posed ethical problems. Data were analyzed using Strauss and Corbin's method. MAIN OUTCOME FINDINGS: The 277 clinical situations were classified under nine themes: ethics; confidentiality; consent, refusal of treatment, and the right to information; level of care and abstention from and cessation of treatment; relationships with pharmaceutical companies and the ethics of research; ethics of teaching; allocation of resources; influence of third parties; and euthanasia and assisted suicide. Learning objectives were developed. CONCLUSION: This research forms the basis of the ethics curriculum in the family medicine residency program at Laval University. It also offers a strategy for integrating ethics into daily teaching activities because the learning objectives derive directly from the concerns of the teaching faculty.

Adult↗
PubMed1999

How effective are supplementary doses of opioids for dyspnea in terminally ill cancer patients? A randomized continuous sequential clinical trial.

Supplementary doses of opioids are recommended to relieve dyspnea in terminally ill cancer patients. We conducted a randomized continuous sequential clinical trial to evaluate their efficacy. We recruited 33 terminally ill cancer patients from three palliative care centers, all of whom had persistent dyspnea after rest and treatment with oxygen. Patients formed 15 successive pairs matched on route of administration. Within each pair, the order of allocation was randomly assigned, one patient receiving 25%, the other 50% of his 4-hourly opioid dose. Five measurements of dyspnea intensity and respiratory frequency were made during 4 hours of follow-up. For each pair, a preference was attributed to the more effective regimen. The two regimens received an almost equal number of paired preferences (8 vs. 7). Overall, both mean dyspnea intensity and respiratory frequency decreased significantly relative to baseline. Dyspnea reduction was relatively greater in patients with initially low and moderate dyspnea intensity. In terminally ill cancer patients with persistent dyspnea, 25% of the equivalent 4-hourly dose of opioid may be sufficient to reduce both dyspnea intensity and tachypnea for 4 hours.

Analgesics, Opioid↗
PubMed1997

Motion-blur illusions.

The still-radii illusion, the figure-of-eight illusion, the band-of-heightened-intensity illusion and the dark-blurred-concentric-circles illusion have remained, until now, isolated relatively ill-explained phenomena. A single algorithmic model is proposed which explains these four visual illusions. In fact, this model predicts phenomena produced by motion of any gray-shaded patterns relative to the eyes (termed 'motion-blur illusions'). Results of a computer simulation of the model are presented. A novel instance of the proposed class of illusions, which can be readily experienced by the reader, is introduced to illustrate the generality of the model.

Computer Simulation↗
PubMed1993

Smooth pursuit along a solid line: a new variation on the theme of efference-copy-bound eye tracking.

Theoretical considerations of the physiology of eye tracking have long implied that the kinematics of smooth pursuit need not parallel those of the pursued target, with pursuit in the absence of a physically moving target as an extreme case. Yet these theoretical implications have been largely ignored, with the consequence that observed kinematic discrepancies between target and pursuit have generally been presented as somewhat surprising, and this view has maintained unnecessary diversity among reported smooth-pursuit phenomena. The case of yet another stimulus-discrepant smooth-pursuit phenomenon is presented and is used to suggest a role which recognized eye-tracking theory might advantageously play in classifying smooth-pursuit phenomena. The new phenomenon, smooth pursuit along a stationary solid straight line under continuous illumination, was demonstrated in a study where eye movements were documented by continuous recordings of the electrooculogram. All twelve subjects were able to initiate smooth pursuit along the line and to maintain it in the absence of any other source of stimulation, and all reported experiencing apparent movement during smooth pursuit. It is suggested that smooth-pursuit phenomena can best be classified in terms of degree of efference-copy dependency.

Adolescent↗
PubMed1984

[Rape by 2 assaillants and gang rape in Montreal].

A survey was conducted in 230 cases of rape and rape attempts heard in the Judicial District of Montreal between January 1975 and May 1978. Data were compiled from the 30 assaults including two or more assaillants. Results show that in cases of rape committed by two men the aggressors are older than gang rapists, meet the victim mainly in her flat or in a bar, and rape her in her own home, in a car or a hotel. In these cases, voyeurism seems to be an important factor since, most of the time, rape is committed by only one of the two aggressors. On the other hand, gang rapists are younger, meet the victim in public places, on the street or when she is hitch-hiking and attack her in one of the aggressors' house, in public places or on the street. Exhibitionism seems more present in this group of rapists. For both groups the victims are mainly single, younger than the aggressors and have diverse occupations. Finally, regarding the legal outcome half of the subjects were liberated or acquitted in both groups. Rape committed by two men had never been studied or compared with gang rape up until now. Results of this survey show dynamic and demographic differences between these two groups of sexual delinquents.

Adolescent↗