The vertebrate brain’s cerebrum is covered by an outer layer, or cortex, that is largely responsible for higher brain functions, including sensation, voluntary muscle movement, thought, reasoning, and memory. It is composed of unmyelinated fibers that—in preserved brains—are grey in color, hence the name “grey matter.” Each region of the cerebral cortex is highly differentiated and sends and receives information specific to its function. How thick is the cerebral cortex in humans? Discuss
Source: The Free Dictionary
A congenital heart defect (CHD) is a flaw in the structure of the heart and great vessels of a newborn. Most CHDs either obstruct blood flow to the heart or nearby vessels or cause blood to flow through the heart in an abnormal pattern. Though such defects occur in less than 1% of the population, they are the leading cause of birth defect-related deaths. There are 8 defects that comprise the bulk of all CHDs, with ventricular septal defects presenting most commonly. What is the septum? 
At 965,000 sq mi (2,499,350 sq km), the Mediterranean Sea is the world’s largest inland sea. It is surrounded by Europe, Asia, and Africa, and is linked to the Atlantic Ocean via the Strait of Gibraltar. Known as the “cradle of civilization,” it was a superhighway of transport in ancient times, allowing for trade and cultural exchange between communities in the area. The regions surrounding the sea have typically warm, dry, sunny climates. How many states have a coastline on the Mediterranean? 
The clepsydra, or water clock, is an ancient timekeeper that operates by measuring the regulated flow of liquid into or out of a vessel. It is believed to have been used in Egypt as early as 2,000 BCE, making it one of the earliest known time-measurement devices. Early water clocks were calibrated with a sundial, and they remained the most accurate timekeeping devices until the invention of the pendulum clock in the 17th century. When did knowing the time become important to the common man? 
In 1964, Prometheus, a Great Basin Bristlecone Pine, was the oldest known non-clonal organism on Earth. That year, a graduate student cut down the 5,000- year-old tree to examine its ring growth patterns and derive information about the climate. It is unclear who suggested that Prometheus be cut down, why the action was deemed necessary, and whether its impact was fully understood at the time. Methuselah is currently the oldest known living tree. How old is it? 
An o-ring is a rubber ring that is used in machinery as a seal against substances like oil and air. Although it is one of the most commonly used seals, it is forever linked to a catastrophic failure. After the space shuttle Challenger exploded in 1986, investigators determined that the o-ring seal in one of the shuttle’s solid fuel rockets failed due to a loss of elasticity that resulted from the low temperature at launch time. How was this problem later demonstrated at a news conference? 
Paul Klee was a Swiss painter, graphic artist, art theorist, and violinist. His early introduction to music played a large role in the way he approached his art and its imagery. Klee often varied the media and style in which he worked and produced over 10,000 works before his death. He also taught at the Bauhaus school of art and architecture with his friend and fellow artist Wassily Kandinsky. During WWI, Klee served in the German army; what was his job? 
The Death of Marat, painted by Jacques-Louis David, depicts the 1793 assassination of radical journalist and revolutionary activist Jean-Paul Marat and is one of the most famous images of the French Revolution. Marat was stabbed while writing in his bathtub, and his murderer’s name is written on the paper he holds in the painting. David’s representation of this scene is reminiscent of depictions of Christian martyrs in religious works. What is the political significance of this imagery? 
Traditionally, olive oil, a yellow to greenish vegetable oil, was produced by crushing olives in mortars or beam presses. Modern processing involves mixing a ground olive paste with water, and extracting the oil using a centrifuge. The olive tree is native to the Mediterranean basin, where olive oil has been used for millennia as lighting fuel, anointing oil, and in food preparation. Recent scientific evidence suggests olive oil may reduce the risk of heart attacks and strokes; how? 
The mandala, meaning circle or completion, is a ritualistic diagram that has spiritual significance in Hinduism and Buddhism. Representing a microcosm of the universe and the totality of existence, it serves as a collection point for gods and universal powers. Its symmetric geometric shapes draw the viewer’s attention to a central meditative point. A Tibetan sand mandala is created over the course of days or weeks only to be swept away upon completion. What does this represent?