pin down

"While puberty offers a clear start, the end of adolescence is much harder to pin down scientifically. Based purely on neural architecture, we found that adolescent-like changes in brain structure end around the early thirties."

Another crucial part of the research involved pinning down the age of the fossils and reconstructing the ancient environments in which these hominins lived.

Although earlier studies have identified individual steps occurring at the electrodes during ammonia formation, the full sequence of events has remained difficult to pin down.

But that wasn’t all — Wen tried a second time to jump the barricades that lined the event’s yellow carpet but was pinned down by security, the BBC said.

Warrant Officer Michael Webber, 43, had pinned down Beck and tried to kiss her.