Friday, March 30, 2007
From the east of the Andes, the Amazon Rainforest begins. It is the biggest rainforest in the world and is of great ecological significance, as its biomass is capable of absorbing enormous amounts of carbon dioxide. Conservation of the Amazon Rainforest has been a main issue in recent years.
The rainforest is supported by the extremely wet climate of the Amazon basin. The Amazon, and its hundreds of tributaries, flow gradually across the landscape, with an enormously shallow gradient sending them towards the sea: Manaus, 1,600 km (1,000 mi) from the Atlantic, is only 44 m (144 ft) above sea level.
The biodiversity within the rainforest is extraordinary: the region is home to at least 2.5 million insect species, tens of thousands of plants, and some 2,000 birds and mammals. One fifth of all the world's species of birds can be found in the Amazon rainforest.
The diversity of plant species in the Amazon basin is the highest on Earth. Some experts estimate that one square kilometre may contain over 75,000 types of trees and 150,000 species of higher plants. One square kilometre of Amazon rainforest can contain about 90,000 tons of living plants.
Monday, March 26, 2007
In optics, a prism is a transparent optical element by means of flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use "prism" typically refers to this type. Some types of optical prisms are not in fact in the shape of geometric prisms. Prisms are characteristically made out of glass, but can be made from any material that is transparent to the wavelengths for which they are designed.
A prism can be used to break light up into its constituent spectral colors (the colors of the rainbow). They can also be used to reflect light, or to split light into components with different polarizations.
Wednesday, March 21, 2007
A camera is a device used to take pictures (usually photographs), also singly or in sequence, with or without sound, such as with video cameras. The name is derived from camera obscura, Latin for "dark chamber", an early mechanism for projecting images in which an entire room functioned much as the internal workings of a modern photographic camera, except there was no way at this time to record the image short of physically tracing it. Cameras may work with the visual spectrum or other portions of the electromagnetic spectrum.
Friday, March 16, 2007
Ice can also be an obstacle; for harbors near the poles, being ice-free is an significant advantage, ideally all-year round. Examples are Murmansk (Russia), Petsamo (Russia, formerly Finland) and Vardø (Norway). Harbors that are not ice-free are opened up using icebreakers.
Ice forming on roads is a unsafe winter hazard. Black ice is very difficult to see because it lacks the predictable glossy surface. Whenever there is freezing rain or snow that occurs at a temperature near the melting point, it is common for ice to build up on the windows of vehicles. Driving safely requires the removal of the ice build-up. Ice scrapers are tools designed to break the ice free and clear the windows, while removing the ice can be a long and labor-intensive process.
Far enough below the freezing point, a thin layer of ice crystals can form on the inside surface of windows. This frequently happens when a vehicle has been left alone after being driven for a while, but can happen while driving if the outside temperature is low enough. Moisture from the driver's breath is the source of water for the crystals. It is troublesome to take away this form of ice, so people often open their windows somewhat when the vehicle is parked in order to let the moisture dissipate, and it is now common for cars to have rear-window defrosters to combat the problem. A similar problem can happen in homes, which is one reason why many colder regions require double-pane windows for insulation.
When the outdoor temperature stays below freezing for comprehensive periods, very thick layers of ice can form on lakes and other bodies of water (although places with flowing water require much colder temperatures). The ice can become thick enough to drive onto with automobiles and trucks. Doing this safely requires a thickness of at least 30 centimeters (one foot).
Sunday, March 11, 2007
Cheese is a solid food prepared from the milk of cows, goats, sheep, and other mammals. Cheese is made by curdling milk using a mixture of rennet (or rennet substitutes) and acidification. Bacteria acidify the milk and play a role in essential the texture and flavor of most cheeses. Some cheeses also feature molds, either on the outer rind or all through.
There are hundreds of types of cheese produced all over the world. Different styles and flavors of cheese are the result of using milk from various mammals or with different butterfat contents, employing particular species of bacteria and molds, and varying the length of aging and other dealing out treatments. Other factors contain animal diet and the addition of flavoring agents such as herbs, spices, or wood smoke. Whether the milk is pasteurized may also affect the flavor. The yellow to red coloring of many cheeses is a result of adding annatto. Cheeses are eaten both on their own and cooked as part of a variety of dishes; most cheeses melt when heated.
For a few cheeses, the milk is curdled by adding together acids such as vinegar or lemon juice. Most cheeses, however, are acidified to a lesser degree by bacteria, which turn milk sugars into lactic acid, followed by the addition of rennet to complete the curdling. Rennet is an enzyme mixture conventionally obtained from the stomach lining of young cattle, but now also laboratory created. Vegetarian alternatives to rennet are available; most are formed by fermentation of the fungus Mucor miehei, but others have been extracted from a variety of species of the Cynara thistle family.
Tuesday, March 06, 2007
The Leaning Tower of Pisa (Italian: Torre pendente di Pisa) or simply The Tower of Pisa (La Torre di Pisa) is the campanile, or self-supporting bell tower, of the cathedral of the Italian city of Pisa. It is situated behind the Cathedral and it is the third structure in Pisa's Campo dei Miracoli (field of Miracles).
Although planned to stand vertically, the tower began leaning to the southeast soon after the onset of construction in 1173 due to a poorly laid foundation and loose substrate that has permitted the foundation to shift.
The height of the tower is 55.86 m (183.27 ft) from the ground on the lowest side and 56.70 m (186.02 ft) on the highest side. The width of the walls at the base is 4.09 m (13.42 ft) and at the top 2.48 m (8.14 ft). Its weight is estimated at 14,500 tonnes. The tower has 294 steps.
The Tower of Pisa was a work of art, performed in three stages over a period of about 174 years. Construction of the first floor of the white marble campanile began on August 9, 1173, a period of military success and prosperity. This first floor is enclosed by pillars with classical capitals, leaning against blind arches. Today, it is still unscarred from centuries of weather and age.
Thursday, March 01, 2007
A lollipop, or lolly, is a type of confectionery consisting mostly of hardened, flavoured sucrose with corn syrup mounted on a stick and intended for sucking or licking. In many regions of the United States, the term "sucker" is used interchangeably with or instead of "lollipop". In these areas, the term "lollipop" is frequently applied to candy that is disc-shaped, while "sucker" is applied to candy that is spherical. Lollipops come in a variety of flavors from cherry, grape and orange to watermelon and green apple. In Europe, particularly the Nordic countries, Germany and the Netherlands, salmiakki-flavoured lollipops are also available, but these are largely unknown to the USA. With numerous companies producing lollipops, the candy now comes in dozens of flavors.They were first commercially manufactured on a large scale in the 1920s.
Some lollipops contain fillings, such as bubble gum or Tootsie Rolls. Notable brand names include Chupa Chups and DumDums. The origin of the lollipop has yet to be determined. Both Racine, Wisconsin and San Francisco, California, claim that they made the first automatic lollipop maker.