Pre-exposure prophylaxis (PrEP) is a course of HIV drugs taken daily by HIV negative people most at risk of HIV to reduce their risk of HIV infection. Truvada is currently the only drug approved for use as PrEP. Truvada is a single pill that is a combination of two anti-HIV drugs, tenofovir and emtricitabine.
Astronomical spectroscopy is one of the most powerful tools used by astronomers to gain a fundamental understanding of our universe. Astronomical spectroscopy is a technique in which the absorption and emission of electromagnetic radiation from stars and other celestial objects are studied.he absorption and or emission spectra of a molecule generally consist of a number of lines. These lines correspond to the discrete differences in the internal energy modes of a molecule.
Electromagnetic radiation can be described in terms of a stream of mass-less particles, called photons, each traveling in a wave-like pattern at the speed of light. Each photon contains a certain amount of energy. The different types of radiation are defined by the the amount of energy found in the photons.Radio waves have photons with low energies, microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and, the most energetic of all, gamma-rays.lectromagnetic radiation can be described in terms of a stream of mass-less particles, called photons, each traveling in a wave-like pattern at the speed of light. Each photon contains a certain amount of energy. The different types of radiation are defined by the the amount of energy found in the photons.