Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Three-dimensional vortex structures in the flow during a stroke cycle, where the time stamp from (a) to (d) is 0.37, 0.51, 0.58 and 0.78T. The vortex loop from the downstroke is marked by a dashed line. The thick arrow in (d) indicates the location where the LEV is pinched off. (Online version in colour.)
