Biomedical subjects

H Almirall

Publications and source records attributed to H Almirall.

10 recordsLinked to original sources

PubMed1997

Main trends in rectal temperature during sleep. Hypnogram and thermogram.

Changes in sleep state and night-time body temperature were studied in 13 healthy young men. Temperature data showed serial dependence that was removed when considering three main segments of the thermogram: an initial rapid drop between 60 and 140 min after lights off, followed by a slower decrease to the thermal minimum and a final temperature increase until waking. The first segment was fitted by a two-term function, while the other two segments were fitted by linear regression. Temperature data obtained after fitting these models were stationary and used to calculate the fast Fourier transformation and the cross-correlation functions between the hypnogram and the thermogram of each subject. Attaining stationarity has unmasked short oscillations during sleep and some temperature series showed the presence of ultradian oscillations with a period of 90-100 min. Significant cross-correlations between sleep stages and body temperature were found, and the parameters of the two-term function fitted to the first temperature drop were related to the sign of the correlation and to that time series (sleep or temperature) which preceded the other during the night.

Adult↗

PubMed1996

Individual differences in body temperature assessed by a two-term function.

A new approximation, an alternative to the cosine function, was used to analyze body temperature throughout the day. The model studied is a two-term function characterized by three parameters that describe the temperature rise and fall. In contrast to other cyclic functions, this function can easily model complete cycles as well as segments of a cycle. This function has been applied to temperature series validating the dimension of morningness-eveningness throughout the day and also to studies that include body temperature, personality factors, and the dimension of morningness throughout a complete circadian period.

Adult↗

PubMed1993

Temperature drop and sleep: testing the contribution of SWS in keeping cool.

Sleep and body temperature characteristics were studied in man in baseline (B), 24 h-constant routine (CR) and recovery (R) after the CR. The sleep advanced and deepened the trough of the minimum temperature when compared with CR. No relevant difference in minimum body temperature, or in the slope of temperature decrease was found, however, between B and R sleeping nights. No correlation was found between the amount of slow wave sleep and body cooling. The results do not support a homeostatic role of slow wave sleep in brain and/or body cooling.

Adult↗

PubMed1993

On the evolution of waking and sleeping.

1. The aim of this paper is to present a new hypothesis to explain the evolution of the sleeping and waking states. 2. We propose that the reptilian waking state and the mammalian slow wave sleep are homologous states. 3. We also propose that instead of looking at the polygraphic sleep as a new evolutive acquisition of mammals and birds, it seems more convenient to look at the full waking state; the "advanced wakefulness" as the true new evolutionary acquisition of these animals. 4. These conclusions are reached after examining some available reports of slow wave electroencephalogram in waking reptiles, some other reports showing signs of rapid eye movement sleep in this same group and the coevolution between sleep states and thermoregulation. Finally, a clear parallelism between sleep ontogeny and phylogeny is shown under the light of the proposed hypothesis.

Aging↗

PubMed1993

Including neither-type in the morningness-eveningness dimension decreases the robustness of the model.

The present paper is a study of axillary temperature and performance during the waking part of the day and the relationship of these two variables to Morningness-Eveningness preferences. A reduced scale of the Horne and Ostberg questionnaire was adapted and standardized for the Spanish population, and 3 groups of subjects were formed (Morning-types: 3 men, 2 women; Neither-type: 3 men, 6 women; Evening-types: 1 man, 4 women). Three different tasks were tested, auditory reaction time (to measure alertness and speed), index finger tapping (motor skill), and verbal memory (information processing). The subjects were tested hourly in 13 sessions spread out over the day. Morningness-Eveningness preference groups did not differ in temperature and performance. Neither-type subjects did not present values intermediate between those of the Morning- and Evening-types.

Acoustic Stimulation↗

PubMed1992

The influence of age, work schedule and personality on morningness dimension.

The effects of age, work schedule and personality were investigated in 908 subjects by means of a reduced scale of Morningness-Eveningness-Questionnaire which contains questions regarding only the Morningness dimension. The results obtained for the work schedule and age maximized the inter-groups differences and the effects as compared to the original questionnaire. Extraversion correlated negatively with Morningness scores, while Sex and Neuroticism were not significantly related to this dimension.

Adolescent↗

PubMed1991

Active microwave computed brain tomography: the response to a challenge.

The potential application of active microwave techniques to brain imaging is studied by numerical simulations and experimentally using a recently developed cylindrical microwave scanner. The potential advantages and limitations of this method in static and dynamic brain imaging are presented and compared with other imaging techniques.

Animals↗

PubMed1988

External auditory canal temperature and reaction time relationship during long performances.

In order to study the relationship between body temperature and reaction time (RT), and check the hypothesis proposed by Kleitman (Sleep and Wakefulness, University Press, Chicago, 1963) about a 'Basic Rest-Activity Cycle' (BRAC), RT tasks were delivered to 24 subjects at 10-min intervals for 320 min, while simultaneously registering bilateral ear canal temperatures. Time series analyses in frequency and time domains were applied to the data. Our results did not show a 90-100 min ultradian rhythmicity in the performance of RT tasks, but 6 of the 24 subjects presented significant periods within limits of BRAC in temperature.

Adult↗

PubMed1988

Ultradian cyclicity in auditory and visual reaction time during long performance.

24 subjects were tested to check the hypothesis proposed by Kleitman about a "basic rest-activity cycle". Reaction time tasks were delivered at 10-min. intervals for 320 min. Spectral density function analyses showed no significant periods within the limits of the cycle. Discussion concerns fulfilling assumptions of spectral analysis and Fisher's test.

Adult↗

PubMed1987

Auditory and visual reaction time in adults during long performance.

Better to understand the relation of auditory to visual reaction time (RT) tasks during a long period (320 min.) as well as the evolution of these performances along time, 24 subjects were tested. RT tasks were delivered at 10-min. intervals for 320 min. Correlations between auditory and visual RTs and cross-correlation functions were calculated. Our results confirmed their association, which was maintained throughout the experiment. There were no significant differences in the mean RT by sex or time of day; however, differences were found for the trend slope between type of stimulus and sex.

Adult↗