Glossary
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| Term | Definition |
|---|---|
| Permafrost thaw | The warming and melting of permanently frozen ground, which can damage buildings and infrastructure and release stored carbon, amplifying climate change. Climate Change |
| Persecuted victim | Portraying oneself or one's group as being attacked or suppressed by powerful forces, which is used to explain away lack of support. Science Literacy |
| Personal incredulity | Rejecting a claim because it is hard to understand or imagine, such as doubting evolution because it seems unlikely. Science Literacy |
| Pertussis (whooping cough) | A highly contagious bacterial respiratory infection that causes severe coughing fits. It is most dangerous for infants and is prevented by DTaP and Tdap vaccines. Vaccines |
| Petrostates | Nations whose economies depend on fossil fuels have long invested in campaigns to undermine climate science, obstruct international agreements, and frame environmental action as a threat to national sovereignty. Their influence extends into global energy markets, diplomacy, and media ecosystems, ensuring that scientific warnings about planetary risk are met with political inertia. Science General |
| PH | A scale from 0 to 14 that measures how acidic or basic a solution is. 7 is neutral, and each step represents a tenfold change. Science General |
| Phase I trial | The first stage of human clinical trials, testing a vaccine's safety and immune response in a small group of healthy volunteers, usually 20 to 100 people. Vaccines |
| Phase II trial | The second stage of clinical trials, involving hundreds of people, to further assess safety, find the best dose, and measure immune responses. Vaccines |
| Phase III trial | The large-scale stage of clinical trials, involving thousands to tens of thousands of people, that measures how well a vaccine prevents disease and detects less common side effects. Vaccines |
| Phase IV (post-marketing surveillance) | Ongoing monitoring of a vaccine's safety and effectiveness after it is licensed and in wide use, which can detect very rare side effects. Vaccines |