The birds that were eating at the bird feeder initially flew away when the shadow of Charlie’s kite passed over the feeder. However, after Charlie had been flying the kite for 15 minutes, the birds had all returned and didn’t stop feeding when the kite passed overhead. The birds’ change in responsiveness illustrates the learning process known as:

a. sensitization
b. habituation
c. second-order conditioning
d. negative reinforcement

The deserts of the sahara and australia are associated with

How do diseases caused by bacteria and diseases caused by viruses react to antibiotics?

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i.e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).