Relapsing fever, as its name implies, is an illness characterized primarily by recurrent episodes of fever, often accompanied by fatigue, malaise and other constitutional symptoms. It is caused by at least 15 spirochete species belonging to the genus Borrelia, and can be vectored to humans by either lice or ticks. Louse-borne relapsing fever (LBRF) is caused by Borrelia recurrentis and is transmitted from human to human by the body louse, Pediculus humanus humanus.
This means that the calendar has a cycle of 400 years as far as leap years are concerned. Every 400 years the same leap year schedule appears. During that cycle, 97 leap years occur (once every 4 years except 3 century changes, so 400 / 4 - 3 = 97). By pure coincidence, this happens to be just an integral number of weeks as well This means that every 400 years the Gregorian calendar repeats itself exactly on the same days of the week!
Discussion Questions These questions can be used for group discussion or for written answers in the studentsâ learning logs. 1. How many days does it take for the Earth to make one revolution of the Sun? Answer: The Earth takes 365 Â¼ days to revolve around the Sun. This is known as one Earth year. Each planet takes a different amount of time to rotate around the Sun. 2. How many times will the Earth rotate as it goes around the sun once? Answer: The Earth rotates 365 Â¼ times as it revolves around the Sun. This is also the number of days in one Earth year. 3. If it takes 365 Â¼ days for the Earth to go around the Sun, but each year only has 365 days, what happens to the Â¼ day? Answer: Leap Year occurs every 4 years. This is because each 4 times around the Sun, there is a total of one extra day. (Â¼ + Â¼ + Â¼ + Â¼ = 1) This day is added on February 29th every fourth year, making that year 366 days long. 4. How many times does the Moon orbit the Earth in one Earth year? Answer: About 12, or 12.3 times. This is why we have about twelve full moons each year. 5. Does the Moon give off its own light? How do you know? Answer: No, in this model, the Moon is represented by a Styrofoam ball and does not give off light. 6.