Voluntary breath-holding in the morning and in the evening
Bibliographic record
Abstract
The aim of the present study was to determine whether or not voluntary breath-holding time (BHT) changes with the time of the day. BHT with airways closed at end-expiration was measured in six male subjects in the sitting position during the morning (08.00-12.00 hours, on days 1, 6, 7 and 8) and evening (20.00-24.00 hours, on days 2 and 4). BHT increased with the number of days of testing and, at day 8, the morning values averaged 160% of those on day 1. Also, Delta P ACO2 [the difference between end-tidal partial pressure of CO2 ( P CO2) and alveolar P CO2 ( P ACO2) at the breaking point] increased in proportion to BHT. Hence the BHT/Delta P ACO2 ratio remained nearly constant. Voluntary hyperventilation prolonged BHT and increased Delta P ACO2. Conversely, in hypoxia (13% O2 for 1-2 h), BHT and Delta P ACO2 were reduced proportionally. During the evening sessions, most of the BHT/Delta P ACO2 ratios in normoxia, hypoxia or after hyperventilation were higher than the corresponding morning values, with the group difference reaching statistical significance for the measurements in normoxia and hypoxia. In conclusion, voluntary BHT varies in both duration and its relationship with Delta P ACO2 between the morning and evening hours. The results should also imply that, with an interruption of breathing, changes in alveolar and arterial gases are not the same at different times of the day.
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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) | 0.002 | 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".