Due to reciprocity (discussed above) the gain of an antenna used for transmitting must be proportional to its effective area when used for receiving. Consider an antenna with no loss, that is, one whose electrical efficiency is 100%. It can be shown that its effective area averaged over all directions must be equal to 2/4, the wavelength squared divided by 4. Gain is defined such that the average gain over all directions for an antenna with 100% electrical efficiency is equal to 1. Therefore, the effective area Aeff in terms of the gain G in a given direction is given by:
Another term for the effective area is?
Aeff

The Cold War saw periods of both heightened tension and relative calm. International crises arose, such as the Berlin Blockade (19481949), the Korean War (19501953), the Berlin Crisis of 1961, the Vietnam War (19591975), the Cuban Missile Crisis (1962), the Soviet war in Afghanistan (19791989) and NATO exercises in November 1983. There were also periods of reduced tension as both sides sought detente. Direct military attacks on adversaries were deterred by the potential for mutual assured destruction using deliverable nuclear weapons. In the Cold War era, the Generation of Love and the rise of computers changed society in very different, complex ways, including higher social and local mobility.
When did the Cuban Missile crisis happen?
1962

Protein digestion occurs in the stomach and duodenum in which 3 main enzymes, pepsin secreted by the stomach and trypsin and chymotrypsin secreted by the pancreas, break down food proteins into polypeptides that are then broken down by various exopeptidases and dipeptidases into amino acids. The digestive enzymes however are mostly secreted as their inactive precursors, the zymogens. For example, trypsin is secreted by pancreas in the form of trypsinogen, which is activated in the duodenum by enterokinase to form trypsin. Trypsin then cleaves proteins to smaller polypeptides.
What are the three main enzymes that break down food?
pepsin secreted by the stomach and trypsin and chymotrypsin