Recently, Russian cosmonauts found that bone health could be reasonably maintained up to what period of time if vigorous exercise in the form of treadmill walking and running was maintained while in space?

A breakthrough in the scientific field of ________ ultimately led to the world's first psychology laboratory

a. chemistry b. botany c. biology d. sociology e. geology

Partial, or __________, reinforcement is a method in which responses are sometimes reinforced and sometimes not

a. trace b. porous c. delayed d. intermittent