Dear Tennis players, how do you hold a racket when serving? I’ve been told to put my knuckles on notch (is that what it’s called?) 2 When serving but I feel much more comfortable when putting my knuckles on notch 4.
Pls help

Investigator a has biological specimens that are coded and linked to identifiers of the source individuals. investigator a provides the specimens to investigator b but does not provide the individual identifiers. investigator b agrees not to re-identify the source individuals. is investigator b's research using the biospecimens human subjects research according to the definition of human subjects research in the federal regulations?