Quantification of the cerebral pressure–flow relationship directional sensitivity: Reliability of shorter repeated squat–stand durations
Bibliographic record
Abstract
Abstract The magnitude of changes in middle cerebral artery mean blood velocity (MCAv) is attenuated when mean arterial pressure (MAP) increases compared with when MAP decreases. This directional sensitivity has been characterized using a time‐corrected ratio calculated on MCAv and MAP changes induced by repeated squat–stands (RSS) at 0.05 and 0.10 Hz for 300 s (∆MCAv T /∆MAP T ). Herein, we examined the reliability of the metric within reduced RSS durations. Ninety‐nine (25 females) healthy human participants (26 ± 5 years) performed 300 s RSS at 0.05 Hz (20 s cycles) and 0.10 Hz (10 s cycles) while MCAv and MAP were measured continuously. The ∆MCAv T /∆MAP T was calculated for each transition [increase (INC); decrease (DEC)] of MAP for 60, 120, 180, 240 and 300 s. A two‐way ANOVA was completed, and the absolute (Bland–Altman plot) and relative (coefficient of variation and intraclass correlation coefficient) reliability were calculated to compare shorter‐duration recordings with 300 s (reference standard). At 0.05 Hz, ∆MCAv T /∆MAP T was similar between INC and DEC and comparable to the 300 s reference from 120 s onwards. At 0.10 Hz, ∆MCAv T /∆MAP T was lower during INC ( p < 0.0001). Bland–Altman plots indicated that differences trended towards zero (greater agreement) with increasing duration. Averaged coefficients of variation were <10% from 120 s (0.05 Hz) and 60 s (0.10 Hz) onwards. All intraclass correlation coefficients were >0.90 for recordings of ≥180 s in both frequencies. Although the 300 s reference is optimal, RSS duration could be shortened to 180 s, if needed, to identify this hysteresis‐like pattern reliably using ∆MCAv T /∆MAP T .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".