Bulbs, corms, and tubers are all parts of a plant that grow underground. They are each a storage unit for food that gives the plant the energy it needs to grow, bloom, and complete its life cycle each year. A bulb is an underground stem and leaf. It grows in protective layers, much like an onion. At the very center of the bulb is a small version of the flower itself. The bulb’s basil plate—a round and flat hairy mass (the beginnings of roots) on the bottom of the bulb—helps the bulb stay together. Examples of bulbs include tulips, daffodils, lilies, narcissus, and amaryllis. A corm is an underground stem. It has the same type of protective covering and basal plate as the bulb, but it does not grow in layers. Instead, the corm is the base for the flower stem and has a solid texture. Crocuses and gladiolus are both corms. The tuber is an underground stem or root. Just like a potato, it has leathery skin, lots of “eyes,” and no basal plate. The eyes are the growing points where the plants eventually emerge. Dahlias, begonias, and anemones are all tubers.
Television works through a series of complicated processes. It starts with a television camera, which takes pictures of scenes. Photo cells inside the camera change the pictures to electrical signals. At the same time, a microphone records sounds that are occurring during the scenes. A vibrating magnet in the microphone changes these sounds into electrical signals, too. Some television shows, like news reports, are recorded live, which means that they are broadcast to homes as they occur. But most of the television programs that we watch are recorded, which means that they are put on videotape and sent out later. The electrical signals of sound and pictures are stored as magnetic signals on videotape, which are converted back to electrical signals when played. Before a program is broadcast, its electrical picture and sound signals are run through a device called a television transmitter. With the help of strong magnets, the transformer turns the electrical signals into invisible bands of energy called radio waves (similar to visible light waves), which can travel great distances through the air. They can travel directly to outdoor television antennae, which catch the waves and send them to television sets that change them into pictures and sounds again.
Cable companies send electrical picture and sound signals through cables directly to homes. When broadcasting to distant places, communication satellites that orbit Earth are used to bounce or return the waves back to Earth, extending their travel distance. Satellites are necessary because radio waves move in straight lines and cannot bend around the world. When an antenna or satellite dish receives radio waves, it changes them back into electrical signals. A speaker in a television set changes some of the signals back into sound. The pictures are reproduced by special guns at the back of a television set that shoot electron beams at the screen, causing it to glow with tiny dots of different colors. Viewed together, the dots look like a regular picture. The individual pictures that make up a scene are broadcast and received, one after another, at a pace so quick that it looks like continuous action is occurring on the screen. The entire process happens very fast because television stations and broadcast towers are all around and because radio waves travel very quickly, at the speed of light. Radio programs broadcast talk and music across the airwaves using the same technology.
In early England, one man would challenge another to a duel by slapping his face with a glove. The challenge was a serious matter of honour, and if the slapped man did not accept it, he would be branded a coward. Having a chip on your shoulder was kind of an early Wild West equivalent of the glove slap, though generally less mortal in nature.
Boys and men would place a woodchip on their shoulder, challenging anyone who dared knock it off to a fistfight. So, if a man had a “chip on his shoulder,” he was clearly in an aggressive mood and spoiling for a fight.
Technically, no. While it is responsible for receiving and transmitting all messages of pain for the whole body, the brain itself does not have pain receptors.
That means that, if you could somehow gain access to another person’s brain, you could poke it or pinch it and that person would not feel the pain.
The hard pavement surface we now call asphalt was discovered by chance when an Englishman named E. Purnell Hooley accidentally spilled tar onto some crushed stone. Hooley named this new black pavement by taking the last name of Scotsman John MacAdam, who had developed the use of crushed stone for a firm, dry highway, and prefixing it with “tar.” Tarmacadam was a mouthful, however, and was soon shortened to Tarmac. Hooley patented Tarmac in 1903.
Measures refractive indices
Glow-in-the-dark stickers, stars, toys, and clothes, all work by absorbing light and emitting it later. These items contain phosphors, substances such as zinc sulfide that radiate visible light after being energized by natural light. Phosphorescent materials continue to glow after the energizing light is removed. They have electrons that are easily excited to higher energy levels when they absorb light energy.
In phosphorescent materials—such as glow-in-the-dark objects—the excited electrons drop to a lower, but still excited intermediate level and stay there for a period of time before returning to their ground state (original energy level) and emitting the excess energy as visible light.
A jackpot is any large amount of money won through gambling. The word comes from a game of draw poker in which only a player dealt a pair of jacks or better can open.
Several hands are usually dealt before this happens, and with each deal the players must add to the ante, which can grow to a considerable amount of money — the “jack” pot. When two jacks are finally dealt and a player opens the betting, the winner will take the jackpot.
Each year, about 150,000 children are treated in emergency rooms for head injuries that occurred while riding their bikes. Many bike-related injuries could be avoided if riders wore their helmets properly. Wearing a bike helmet reduces the risk of brain injury by as much as 88 percent and reduces the risk of injury to the face by 65 percent. That is why many state laws say that bicyclists under the age of 14 are required to wear approved bicycle helmets when they ride their bicycles. If your friends don’t wear helmets when you bicycle together, teach them by your wise example. In the United States, bicycle helmets save one life every day and prevent one head injury from happening every four minutes.
When you flush the toilet or wash your clothes, the used water, called wastewater, goes down the drain. This wastewater travels through a network of underground pipes known as the sewer system. The city system treats the wastewater to keep it clean. Both large objects, such as sticks, cans, rocks, and small debris, such as gravel and sand, are separated from the wastewater.
It is treated with oxygen, which allows micro-organisms to grow and eat small bits of organics. The wastewater is then recycled and clarified again. The wastewater is then disinfected with chlorine to kill harmful pathogens before being released into a nearby river, lake, or sea. In towns that do not have a sewer system, each house has its own septic system. Toilet water flows into a big underground tank where bacteria helps break down the waste. Then the water flows out into the soil, where it is absorbed.