Circadian rhythms in the chemoreflex control of breathing
Bibliographic record
Abstract
Mechanisms underlying the circadian rhythm in lung ventilation were investigated. Ten healthy male subjects were studied for 36 h using a constant routine protocol to minimize potentially confounding variables. Laboratory light, humidity, and temperature remained constant, subjects did not sleep, and their meals and activities were held to a strict schedule. Respiratory chemoreflex responses were measured every 3 h using an iso-oxic rebreathing technique incorporating prior hyperventilation. Subjects exhibited circadian rhythms in oral temperature and respiratory chemoreflex responses, but not in metabolic rate. Basal ventilation [i.e., at subthreshold end-tidal carbon dioxide partial pressure (PET(CO(2)))] did not vary with time of day, but the ventilatory response to suprathreshold PET(CO(2)) exhibited a rhythm amplitude of approximately 25%, mediated mainly by circadian variations in the CO(2) threshold for tidal volume. We conclude that the circadian rhythm in lung ventilation is not a simple consequence of circadian variations in arousal state and metabolic rate. By raising the chemoreflex threshold, the circadian timing system may increase the propensity for respiratory instability at night.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".