I've seen dynamic memory work better with other guests though, so it might be either something I'm doing wrong, or a side effect of the File Server role. Either way, I've gotten better results with setting static amounts of RAM on my file/DFS servers.
A biological heart valve is a heart valve recovered from a donor or created from donor tissue. A cadaveric valve comes from a human donor. Bovine valves are recovered from cows and porcine valves come from pigs.
Healthy valves open and close in coordination with the pumping action of your heart's atria and ventricles. Each valve has a set of flaps called leaflets or cusps that seal or open the valve. The cusps allow pumped blood to pass through the chambers and into your blood vessels without backing up or flowing backward.