Remote Physiological Signal Acquisition and Analysis: Contactless Photoplethysmography and Specular Reflection Vascular Imaging
Bibliographic record
Abstract
In this thesis, I describe the remote acquisition of physiological signals using contactless remote photoplethysmography (rPPG), and the novel specular reflection vascular imaging (SRVI). rPPG is a contactless extension of reflection photoplethysmography, which captures the variations in skin optical properties due to changes in the primary light absorber in blood - hemoglobin. I used rPPG (embodied in a consumer smartphone) to investigate various physiological phenomena, including ischemia, Mayer waves, venous outflow, and characteristics of glabrous vs. non-glabrous skin. Despite its value, photoplethysmography is limited by sensitivity to melanin concentration, and therefore has performance limitations in acquisition from subjects with darker skin tones. To address this limitation, SRVI was proposed to leverage specular reflection for acquisition of skin displacements caused by mechanical pulsations in blood vessels. SRVI is insensitive to melanin concentration since acquisition is restricted to the very surface of the skin. SRVI was capable of capturing carotid artery and jugular vein waveforms.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".