A cohort is a group of people who share a common characteristic or experience within a defined period (e.g., are currently living, are exposed to a drug or vaccine or pollutant, or undergo a certain medical procedure).
A rift valley is a lowland region formed by the interaction of Earth's tectonic plates. This small rift valley has a typical formationâlong, narrow, and deep. It was formed by the Thingvellir rift, where the North American and Eurasian tectonic plates are tearing, or rifting, apart over a hotspot on the island of Iceland.
Cluster headache (CH) is a neurological disorder characterized by recurrent, severe headaches on one side of the head, typically around the eye.ndividuals typically experience repeated attacks of excruciatingly severe unilateral headache pain. Cluster headache attacks often occur periodically; spontaneous remissions may interrupt active periods of pain, though about 10â15% of chronic CH never remit.