There are multiple definitions:

1. detrended fluctuation analysis(English)

   • HRV, RPDE, ECG, RSA
   • Signal analysis, Electrophysiology, Variability / oscillation
   • https://doi.org…0736(95)80017-4
   • https://doi.org…aat.2012.03.002

2. diagnosis [via indirect] fluorescent antibody(English)

   • clinical laboratory testing method
   • Diagnostics, Veterinary medicine, Fluorescence
   • https://doi.org…155/2013/841978