Network protocols that use aggressive retransmissions to compensate for packet loss due to congestion can increase congestion, even after the initial load has been reduced to a level that would not normally have induced network congestion. Such networks exhibit two stable states under the same level of load.
Beta blocker. Beta blocker, also written Î²-blocker, is a class of medications that are particularly used to manage cardiac arrhythmias, and to protect the heart from a second heart attack (myocardial infarction) after a first heart attack (secondary prevention).
Calcium-channel blockers prevent or slow the flow of calcium into the heart. Drugs in this category include: diltiazem (Dilt, Cardizem, Tilazem, Cartia XT) and verapamil (Calan, Isoptin). Cardiac glycosides slow down and control the heart rate by blocking the electrical conduction between the atria and ventricles.