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Biomedical subjects

B J O'Loughlin

Publications and source records attributed to B J O'Loughlin.

At least 19 recordsLinked to original sources
PubMed1984

Human orientation with restricted sensory information: no evidence for magnetic sensitivity.

Baker claimed that people are also able to orientate themselves to particular geographical locations as a result of sensitivity to the Earth's magnetic field. These claims were disputed by Gould and Able. A study involving a greater number of subjects (n = 103) and more stringent control over environmental sensory cues was carried out to resolve this disagreement. Subjects responded, both with a direct pointing response and with a verbal judgement in terms of an imagined clock face, to the targets of north, home, and the City of Melbourne. In statistical terms, subjects were not able to orientate towards any target by use of either response. No evidence was found for a magnetic sense in humans as claimed by Baker.

Cues↗
PubMed1983

Azarcón por empacho--another cause of lead toxicity.

A new source of toxic lead ingestion has been identified roentgenologically in Mexican-American children and adults. Azarcón is an orange powder that contains 86% to 95% lead tetroxide (Pb3O4). At least three children have been treated with this substance by folk healers for relief of abdominal symptoms. Other Hispanic medical folklores may include this toxic "remedy."

Child↗
PubMed1982

A respiratory mask for resting and exercising dogs.

A respiratory face mask has been developed for use with unsedated beagles trained to run on a treadmill. The latex rubber mask, shaped to fit the animal's muzzle, incorporates two modified, commercially available, pulmonary valves for separating inspiratory and expiratory flows. The mask has a dead space of 30 cm3 and a flow resistance below 1 cmH2O . 1(-1) . s. The flexible mask is used to measure breath-by-breath respiratory variables over extended periods of time during rest and exercise.

Animals↗
PubMed1981

Improving psychoacoustical tuning curves.

The probe signal in psychoacoustical tuning curves stimulates more than one neuron, even when presented at low levels. The subject can "listen" to neurons with characteristic frequencies away from the nominal probe frequency and optimize performance. This "off-frequency listening" can account for much of the discrepancy in the sharpness of tuning between psychoacoustical tuning curves obtained in forward masking and neurophysiological tuning curves. By adding a band-reject noise, centred on the probe frequency, to limit off-frequency listening, results in close agreement with the neurophysiological data can be produced.

Acoustic Stimulation↗
PubMed1981

Off-frequency listening: effects on psychoacoustical tuning curves obtained in simultaneous and forward masking.

Off-frequency listening--the use of information in different frequency regions to improve performance in masking tasks--has been reported to influence psychoacoustical tuning curves measured in simultaneous masking. The present experiment was designed to establish whether suppression has an effect on off-frequency listening. Psychoacoustical tuning curves were obtained from three observers in both simultaneous and forward masking. A probe level of 10 dB SL and narrowband noise maskers were used. After obtaining the conventional tuning curves, a fixed masker, at either 1.8 or 2.2 kHz and 10 dB below the corresponding tuning-curve threshold, was added to limit off-frequency listening. In both simultaneous and forward masking, the branch of the tuning curve opposite the fixed masker was shifted downwards, but to a greater extent in forward masking. The suppression of the probe in tuning curves measured in simultaneous masking appears to constrain off-frequency listening. In forward-masking tuning curves, off-frequency listening has a greater effect, and may explain to a large extent the very sharp tuning which has been found in some studies.

Auditory Threshold↗
PubMed1981

Effect of probe duration on psychoacoustical tuning curves obtained in forward masking.

The duration of the probe affects the sharpness of tuning of psychoacoustical tuning curves obtained in forward masking. With probes of less than 30 ms, a major factor appears to be the increase in the frequency spread of spectral energy with decreasing duration. Even with low-level probes, the redistribution of energy within the mainlobe of the spectrum is considerable and increases off-frequency listening.

Acoustic Stimulation↗
PubMed1980

End-tidal CO2 response to low levels of inspired CO2 in awake beagle dogs.

The steady-state end-tidal CO2 tension (PCO2) was examined during control and 1% CO2 inhalation periods in awake beagle dogs with an intact airway breathing through a low dead-space respiratory mask. A total of eight experiments were performed in four dogs, comprising 31 control observations and 23 CO2 inhalation observations. The 1% inhaled CO2 produced a significant increase in the steady-state end-tidal PCO2 comparable to the expected 1 Torr predicted from conventional CO2 control of ventilation. We conclude that 1% inhaled CO2 results in a hypercapnia. Any protocol that is to resolve the question of whether mechanisms are acting during low levels of inhaled CO2 such that ventilation increases without any change in arterial PCO2 must have sufficient resolving power to discriminate changes in gas tension in magnitude predicted from conventional (i.e., arterial PCO2) control of ventilation.

Animals↗