In the 3rd century BCE, Hippocrates introduced his theory of Humoralism. It was based on the notion that 4 fluids, each corresponding to one of the 4 elements, permeate the human body and cause disease when not in balance. Theories regarding the 4 humors—blood, black bile, yellow bile, and phlegm—expanded over the years, and in the 2nd century CE, Galen published a treatise which associated a specific temperament with each humor. What humor was thought to cause a melancholic disposition? Discuss
Source: The Free Dictionary
A satellite radio is a digital radio that receives signals broadcast by communications satellites. Since satellite radio operates wherever there is line of sight between the antenna and satellite, the signal spans a much wider geographical range than terrestrial radio. Satellite radio service is subscription-based and can only be accessed through specialized receivers. How many satellites are generally needed to provide service to an entire continent? 
The Magyars, a nomadic people, migrated from the Urals to the Northern Caucasus region around 460 CE. They remained there for roughly 400 years, until the advance of the Pechenegs forced them west into what is now Romania. They arrived in Hungary towards the end of the 9th century, displacing the resident Huns and Slavs. The Magyars currently comprise 92% of the Hungarian population; consequently, the words Magyar and Hungarian are used interchangeably. What is the origin of the latter term? 
Hieratic, first used around 3,000 BCE, was the basic writing system of the ancient Egyptian pharaonic period and provided a simpler alternative to the contemporaneous hieroglyphic system. It was generally written with ink on papyrus and was often used to compose administrative documents and letters, as well as legal, literary, and religious texts. Much of what is now known about the lives of common Egyptians has been deciphered from such texts. What writing system is descended from hieratic? 
Dog Whisperer is a National Geographic Channel reality TV series in which Cesar Millan, a self-proclaimed dog behaviorist, rehabilitates unruly dogs and teaches their owners proper canine training techniques. Though he has no formal certification, Millan believes his early observations of his family’s farm dogs give him unique insight into pack mentality. In 2006, Millan published Cesar’s Way, a guide to dog psychology. What are the three principles of Millan’s training philosophy? 
In 2002, Gabon’s president established a national park system that protects about 11% of the country’s land and waters. Included is Mayumba National Park, located on the Atlantic coast of central Africa and dedicated to the protection of marine life. The park shelters a 60 km (37 mi.) strip of beach and coastal vegetation and extends another 15 km (9 mi.) out to sea. Dolphins and whales can often be found in the waters off the coast. What reptile uses the park’s beach as its breeding ground? 
Automotive airbag inflation occurs only milliseconds after crash sensors detect a collision. The airbag’s cushioning effectively prevents direct human impact with dangerous vehicular surfaces and reduces the deceleration passengers experience as they come to a stop. While airbags were initially viewed as an alternative to seatbelts, they are now understood to offer greater protection when used in conjunction with other automotive safety methods. What injuries may result from airbag deployment? 
Andre-Jaques Garnerin used his invention, the parachute, when he undertook the first jump from a hot air balloon in 1797. Since then, parachuting, or skydiving, has been utilized in military operations as well as for recreation and sport. Skydiving typically involves jumping from an aircraft at an altitude of about 4,000 m (13,000 ft), free-falling, and then deploying a parachute to slow the landing. Who holds the record for the highest parachute jump in history? 
These frogs belong to the family Dendrobatidae, a group of small, diurnal, often brightly colored frogs native to Central and South America. These frogs secrete poisonous alkaloids through their skin, which ranges in color from bright orange to black and blue. Most poison frogs are not toxic to humans or animals, but a few secrete a potent neurotoxin that can kill within minutes. Why is it that poison frogs captured from the wild and fed a typical captive diet lose their toxicity? 
On March 24, 1998, Mitchell Johnson, age 13, and Andrew Golden, age 11, opened fire on students and teachers at their Arkansas middle school. Johnson hid in a wooded area and waited while Golden set off the school’s fire alarm. Then, as the building was being evacuated, the two boys shot and killed four students and a teacher; another 10 people were wounded in the shooting. Both boys were apprehended, tried, and convicted. When were they released from custody?