Kallie wants to improve her tennis serve. she already practices every day the court is available, and her technique and energy output are outstanding. kallie should focus on a) frequency; performing more cardio-related workouts b) intensity; increasing the effort expended during her workout c) time; increasing the length of her workout d)type; performing a different activity to achieve her goal

[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine.what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.

What is the function of reverse transcriptase in retroviruses? a) it uses viral rna as a template for dna synthesis.b) it converts host cell rna into viral dna.c) it translates viral rna into proteins.d) it uses viral rna as a template for making complementary rna strands.

Which statement is false? a. an extinction burst is the complete cessation of the target behavior after the extinction procedure has started. b. extinction procedures should not be used with behaviors that cause serious injury to the subject. c. if the behavior analyst does not have the ability to control the subject's access to reinforcement, an extinction procedure should not be implemented. d. spontaneous recovery of the target behavior will be short-lived, as long as the extinction procedure remains in effect