variable

PfEMP1 is a highly variable protein and has long been considered a technically difficult vaccine target.

There are, in fact, hundreds of variables for each patient -- ranging from clinical data and brain imaging to health insurance status.

"We were surprised by how fast the nasal spray worked and by how variable the absorption of the oral drug was even in healthy subjects," Bensimhon said.

Even in human studies, Benítez adds, it is challenging to determine which biological markers to measure and how to adequately describe and quantify something as complex and variable as emotions.

Some tracker and variable rate mortgages move fairly closely in line with the Bank's base rate.