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).
The most widely used drugs in this class are metoprolol, atenolol, and propranolol. Beta receptors exist in other systems of the body, such as the lungs. Some drugs target specifically the receptors in the heart, and are known as cardioselective beta blockers. Examples are metoprolol, atenolol, and acebutolol. Other beta blockers include propranolol and nadolol. The specific drug of choice depends on the patientâs health status and condition being treated.