user: Why was Tamazulapam del Espíritu Santo placed under quarantine?

assistant: Tamazulapam del Espíritu Santo was placed under quarantine due to the COVID-19 pandemic.

user: What is a PCR test?

assistant: PCR stands for "polymerase chain reaction". This test uses cycles of heating and cooling to detect photons that are emitted when a reagent (binder) RNA binds to the viral RNA that has been extracted from the human sample. Each heating and cooling cycle increases (amplifies) the amount of the targeted genetic material in the test tube. If the intensity of the photons does not reach a threshold after a certain number of cycles, the PCR test will result in a "Not Detected" test result.

user: How do archaeologist use stratigraphy?

assistant: Stratigraphy is very important for archaeologists and is used to interpret time and space within a site. In general, the soil horizons near the top are the most recent and those lower down are older. Stratigraphy can help archaeologist determine how old a site is as well as different events that might have taken place at the site.