Viruses cause most cases of pneumonia in preschool-aged children (i.e., four months to five years of age).1, 9, 16, 24 Although most physicians start antibiotic therapy, guidelines allow for withholding treatment if a viral etiology is suspected and close follow-up can be ensured.1, 9, 13, 15, 16, 24 These children usually have associated symptoms of viral infection, such as pharyngitis, rhinorrhea, and diarrhea .1
Backgrounder on Plutonium. Printable Version. Plutonium is a radioactive metallic element with the atomic number 94. It was discovered in 1940 by scientists studying how to split atoms to make atomic bombs. Plutonium is created in a reactor when uranium atoms absorb neutrons.Nearly all plutonium is man-made.rintable Version. Plutonium is a radioactive metallic element with the atomic number 94. It was discovered in 1940 by scientists studying how to split atoms to make atomic bombs. Plutonium is created in a reactor when uranium atoms absorb neutrons. Nearly all plutonium is man-made.
Radioactive isotopes have a variety of applications. Generally, however, they are useful either because we can detect their radioactivity or we can use the energy they release. Radioactive isotopes are effective tracers because their radioactivity is easy to detect.A tracerA substance that can be used to follow the pathway of that substance through some structure. is a substance that can be used to follow the pathway of that substance through some structure.Recall that tritium, H, is a radioactive isotope of hydrogen.). Tracers can also be used to follow the steps of a complex chemical reaction. After incorporating radioactive atoms into reactant molecules, scientists can track where the atoms go by following their radioactivity.