DNA-PPG: A Foundation Model for Photoplethysmography via Dual Neighborhood Alignment

Summary

A direct attack on PaPaGei-S, from the loss function rather than the architecture. The claim is that the two standard ways of building a PPG contrastive objective are both wrong in a specific, fixable way. First, instance discrimination (Apple's 141k-participant model, SimCLR-style) declares every segment from a different subject a negative — which means two people with near-identical pulse morphology get actively pushed apart, distorting the manifold.