A study of 100 injection drug users who tested negative for HIV infection at enrollment had their HIV status retested at 3-month intervals over a 2-year follow-up period. All of the injection drug users were followed for the entire 2-year period. None died and none were lost to follow-up. Required:
What frequency measures of HIV infection can be calculated at the end of the study?

During the sixteenth, seventeenth, and eighteenth centuries, the mentally ill were housed in

Which of the following processes within viral replication is the greatest source of genetic variation in rna virus populations? a) high mutation rate due to lack of proofreading of rna genome replication errors. b) transcription from the host cell rna polymerase introduces numerous mutations. c) capsid proteins from the host cell can replace the viral capsid. d) viral rna is translated by host cell ribosomes.

When comparing the digestive and urinary system, we can conclude that they both