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).
Heart failure. Warfarin, digoxin, asprin and statins. In addition to the triple combination of diuretics, ACE inhibitors and beta-blockers (see 'Beta-blockers, ACE inhibitors, diuretics and aldosterone antagonists') several drugs are commonly prescribed to help relieve symptoms of heart failure.