Bibliographic record
Abstract
High arterial blood pressure, or hypertension, is a major risk factor for cardiovascular diseases. Conventional noninvasive methods for estimating the arterial blood pressure rely on a brachial cuff that is placed around the upper arm. The cuff is inflated to a pressure that exceeds the systolic blood pressure. The heart pulse is monitored while the cuff is slowly deflated. The pressure at which the heart pulse sound can be detected corresponds to the systolic pressure and the pressure at which the heart pulse sound can no longer be detected corresponds to the diastolic pressure. This approach cannot be used on a continuous basis and has many disadvantages, including the fact that the system is cumbersome and causes discomfort to the patient, which may affect their blood pressure value. This thesis proposes two approaches to accurately measure the pulse transit time (PTT). The PTT can be used to estimate arterial blood pressure variations noninvasively, on a continuous basis without the use of a cuff. The correlation between the arterial blood pressure and PTT are verified using bio-signals from the MIMIC II database. The first approach for measuring the PTT relies on the electrocardiogram (ECG) and photo-plethysmograph (PPG) signals. Algorithms based on the empirical mode decomposition (EMD) method and the adaptive filtering techniques are proposed to enhance the corrupted ECG signal. Gaussian-based curve fitting algorithms are proposed to model and extract the embedded characteristic parameters from the original PPG signal. The second approach relies on a novel framework: the Eulerian video magnification (EVM). The color component of the video signal is amplified to reveal subtle change in the skin color. These changes correspond to the blood flow into the arteries. Simulations and experiments are conducted to validate the proposed framework. The results demonstrate that the enhanced ECG and PPG signals can improve the accuracy of the PTT in estimating the arterial blood pressure. The EVM method can capture the characteristics of the wrist pulse signal and detect the heart pulse on different areas of the human skin. This paves the way towards the usage of cameras for continuous arterial blood pressure monitoring.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".