There are multiple definitions:

1. reactive hyperemia index(English)

   • calculated as the ratio of the average amplitude of PAT signal over 1 min starting 1.5 min after cuff deflation (control arm, A; occluded arm, C) divided by the average amplitude of PAT signal of a 2.5 min time period before cuff inflation (baseline) (control arm, B; occluded arm, D). Iis related to multiple traditional and metabolic cardiovascular risk factors, in particular, obesity and obesity-related metabolic risk factors
   • RH, CAVI, FMD, NO, PAT, PWV, VF
   • Diagnostics, Vascular disease, Risk factor, Adiposity, Atherosclerosis /atherogenic, Ratio-based metric
   • https://doi.org…ONAHA.118.11554

2. Regional Harmonisation Initiatives(English)

   • APEC, ASEAN, EFPIA, ICH
   • Ethnicity

3. rubber hand illusion(English)

   • the perceived ownership of an artificial hand which is stimulated with a participant’s occluded hand placed next to it
   • AR, ART, CRPS, FM, MVF, RS
   • Rehabilitation
   • https://doi.org…OC.2013.2294178

4. radiographic Haller index(English)

   • OSA, PE, Pex, SVD
   • Medical imaging
   • https://doi.org…al.pone.0277494

5. repetitive head impact(English)

   • CTE, IL-6, NBD, TES
   • Injury, Brain (dys)function, Sports medicine, Post-traumatic state
   • https://doi.org…974-024-03034-6