a) The appearance of a particular disease in a large number of people at the same time
b) A sudden, widespread occurrence of an undesirable phenomenon
Ex: Is the government capable of preventing a bird flu epidemic?
Ex: I remembered hearing about the cholera epidemic which had struck just before I was born.
Ex: What’s behind the nation’s fatness epidemic?
Ex: We have a sudden epidemic of obesity that has emerged over the past 15 years
Gradually wear away (soil, rock, or land), gradually destroy or be gradually destroyed
Ex: Wind and rain have eroded the statues into shapeless lumps of stone.
Ex: Layered deposits have been partly eroded by the wind in some places
Ex: I used to have immense pride and respect for England but since 1946 that has almost eroded away
Ex: Upon arrival everything was going right, all my worries slowly eroded away
Ex: Numerous hospital bills can cause your savings to erode
to cut off someone’s head, especially as a punishment
Ex: Militants threatened to behead him unless their demand was met.
Ex: His father was beheaded simply because he happened to be the head of a religious body
A plant, Cyamopsis tetragonolobus, of the legume family, grown as a forage crop and for its seeds, which produce a gum (guar gum) used as a thickening agent and stabilizer in foods and pharmaceuticals and as sizing for paper and cloth.
A Sense of Power
Most sharks wouldn’t perform well on an eye exam. If you take a close-up look at a shark’s face, you’ll notice that its eyes are quite small in proportion to the size of its head. Also, a shark’s headlights are usually situated farther back toward its neck, limiting its scope of vision.
Fortunately for sharks (and unfortunately for their prey), they have a sixth sense called electroreception, which enables them to hunt precisely underwater. Special pores around their faces act as homing devices and detect the electrical currents that other organisms emit. The salty aquatic environment transports those electrical currents toward the shark. These five cool components of electroreception demonstrate just how incredible this shark sense is.
Electroreception operates on the same general principles at work inside a battery. Whenever a living organism, such as a fish, contracts a muscle, it creates a faint electrical charge. That charge travels through the salty ocean water, thanks to the sodium and chlorine ions floating throughout it. Those ions possess positive and negative charges, and the fish’s cells are also slightly charged. Therefore, when the living cells on the fish come into contact with the free-floating sodium and chlorine ions, the ions exchange electrons in order to become more stabilized. That electron exchange then creates a weak voltage that sharks can sense.
Perhaps you’re wondering why you haven’t heard of animals on dry land who hunt via electroreception. That’s because the special sense only works in the ocean. To create that faint electrical charge, there must be sodium and chlorine ions (hence, the salt) to facilitate the electron exchange and pass it along. The human body also creates electrical impulses when muscles contract, but the open air doesn’t conduct them away from the body.
Aquatic(s) means relating to water; living in or near water or taking place in water
Ex: Water lilies are aquatic plants
Ex: An aquatic environment.
Ex: Acquatic sports
Ex: Boats are aquatic vehicles
Ex: The pond is quite small but can support many aquatic plants and fish.
As the name implies, a backpack is a bag you carry on your back. In America, often refer to a child’s schoolbag as a backpack, but really a backpack will be adequate for a day or weekend trip. A backpack has two shoulder straps, but on a true backpack, the shoulder straps actually carry very little of the weight. Instead, the load is mainly diverted to padded hip belts.
A rucksack is essentially a large, rugged backpack. The word “rucksack” is derived from the German. A rucksack is often used for camping or hiking and has pockets and belts used for holding a more substantial amount of gear compared to a backpack. Rucksacks will also have hip belts and often chest belts as well. A large rucksack is ideal for anything from an extended hiking and camping adventure to travelling around the world.
Both backpacks and rucksacks allow you to carry heavy loads more easily than is possible in a handbag or on the front of your body.