Other viruses that can cause colds include coronavirus, respiratory syncytial virus, influenza and parainfluenza. Colds cause a lot of people to stay home. The CDC says 22 million school days are lost each year in the U.S. because of them. Some estimates say that Americans have 1 billion colds a year. For more detail, see Common Cold Causes. How a Common Cold Starts. You can catch it from another person who is infected with the virus. This can happen by direct physical contact with someone who has a cold, or by touching a surface contaminated with their germs -- like a computer keyboard, doorknob or spoon --- and then touching your nose or mouth.
The hypocaust system. The hypocaust system (hypocaustum in Latin) was a heating system used in (wealthy) Roman homes and Roman baths, and the closest thing to central heating today. The hypocaust was a system that circulated hot air under the floor and surrounding walls. Hypocaust construction
Most of their cheeses were fresh cheeses, though the Romans fully understood the use of rennet to make hard-cheeses, and did. For coagulants, the Roman world used rennet from hare and goat kids, as well as fig tree branch sap, vinegar, thistle flowers, bastard saffron seed, thyme, and an extract from green pineapples.hile normal Roman meals were often meatless, though, people would have been insulted if a banquet did not include meat. Meat would make appearances mostly at special occasions such as these. The Romans considered the Germanic tribes barbarians because they relied so heavily in their diets on meat and animal products.