Monday, February 26, 2007

spear

A spear is an ancient weapon used for hunting and war, consisting of a shaft, generally of wood, with a sharpened head. The head may be just the sharpened end of the shaft itself, as is the case with bamboo spears, or it may be of one more material fastened to the shaft. The most common design is of a metal spearhead, shaped somewhat like a dagger.
Spears were arguably one of the most general personal weapons from the late Bronze Age until the advent of firearms. They may be seen as the ancestor of such weapons as the lance, the halberd, the naginata and the pike. One of the initial weapons fashioned by human beings and their ancestors, it is still used for hunting and fishing, and its influences can still be seen in contemporary military arsenals as the rifle mounted bayonet.
Spears can be used as both melee and ballistic weapons. Spears used mainly for thrusting tend to have heavier and sturdier designs than those intended exclusively for throwing. Two of the most well-known throwing spears are the javelin thrown by the ancient Greeks and the pilum used by the Romans.

Wednesday, February 21, 2007

Bone

Bones are rigid organs that figure out the part of the endoskeleton of vertebrates. Bones job to move, support, and protect the body, produce red and white blood cells and store minerals. Bones come in a variety of shapes and have a complex internal and external structure, allowing them to be lightweight yet strong and hard, while fulfilling their many other functions. One of the types of tissues that makes up bones is the mineralized osseous tissue, also called bone tissue, that gives bones their rigidity and honeycomb-like three-dimensional inside structure. Other tissue types found in bones include marrow, the periosteum, nerves, blood vessels and cartilage.
There are five main functions of bones.
* Protection — Bones can serve to protect internal organs, such as the skull protecting the brain or the ribs protecting the abdomen.
* Shape — Bones provide a frame to keep the body supported.
* Blood production — The marrow, located within the medullary cavity of long bones and the interstices of cancellous bone, produces blood cells in a process called haematopoiesis.
* Mineral storage — Bones act as reserves of minerals important for the body, most notably calcium and phosphorus.
* Movement — Bones, skeletal muscles, tendons, ligaments and joints function together to generate and transfer forces so that individual body parts or the whole body can be manipulated in three-dimensional space. The interaction between bone and muscle is studied in biomechanics.

Thursday, February 15, 2007

Ice cream

Before the growth of modern refrigeration, ice cream was a luxury item kept for special occasions. Making ice cream was quite difficult. Ice was cut commercially from lakes and ponds during the winter and stored in large heaps in holes in the ground or in wood-frame ice houses, insulated by straw. Ice cream was made by hand in a huge bowl enclosed by packed ice and salt. The temperature of the ingredients was reduced by the mix of compressed ice and salt. The salt water was chilled by the ice, and the action of the salt on the ice causes it to (partially) melt, absorbing latent heat bringing the combination below the freezing point of pure water. The wrapped up container can also make better thermal contact with the salty water and ice mixture than it could with ice alone.The hand-cranked churn, which still used ice and salt for cooling, was made-up by an American named Nancy Johnson in 1846, making invention possible on site and avoiding the problem of nonstop chilling between production and consumer. Ice cream became a trendy item for the first time. The world's first business ice cream factory was opened in Baltimore, Maryland in 1851, by Jacob Fussell, a dairy farmer. An unstable demand for his milk led him to mass create ice cream. This allowed the previously expensive invention to be offered in the city at reduced prices.Fussell opened ice cream parlors as far west as Texas. Many were still around well into the twentieth century. Fussell later sold his business to Borden.
The improvement of industrial refrigeration by German engineer Carl von Linde during the 1870s eliminated the need to cut and store natural ice and when the continuous-process freezer was perfected in 1926, allowed commercial mass invention of ice cream and the birth of the modern ice cream industry.The most common method for producing ice cream at home is to use an ice cream maker, in modern times normally an electrical device that churns the ice cream mixture while cooled inside a house freezer, or using ice and salt. A newer method of making home-made ice cream is to add liquid nitrogen to the mixture while moving it using a spoon or spatula.

Thursday, February 08, 2007

Gold

Gold is a extremely sought-after valuable metal that for many centuries has been used as money, a store of value and in ornaments. The metal occurs as nugget or grains in rocks and in alluvial deposits and is one of the coinage metals. It is a soft, glossy, yellow, dense, malleable, and ductile (trivalent and univalent) change metal. Modern manufacturing uses include dentistry and electronics. Gold forms the basis for a financial typical used by the International Monetary Fund (IMF) and the Bank for International resolution (BIS). Its ISO currency code is XAU.
Gold is a tinny element with a trait yellow color, but can also be black or ruby when finely alienated, while colloidal solutions are intensely tinted and often purple. These colors are the effect of gold's plasmon frequency lying in the visible range, which causes red and yellow glow to be reflected, and blue light to be engrossed. Only silver colloids show the same interactions with light, albeit at a shorter occurrence, making silver colloids yellow in color.
Gold is a good conductor of temperature and electricity, and is not precious by air and most reagents. Heat, damp, oxygen, and most corrosive agents have very little chemical effect on gold, making it well-suited for use in coins and jewelry; equally, halogens will chemically alter gold, and aqua regia dissolve it.
Pure gold is too soft for ordinary use and is hard-boiled by alloying with silver, copper, and other metals. Gold and its lots of alloys are most often used in jewelry, coinage and as a typical for monetary exchange in various countries. When promotion it in the form of jewelry, gold is calculated in karats (k), with pure gold being 24k. However, it is more commonly sold in lower capacity of 22k, 18k, and 14k. A lower "k" indicates a higher percent of copper or silver assorted into the alloy, with copper being the more typically used metal between the two. Fourteen karat gold-copper alloy will be almost identical in color to definite bronze alloys, and both may be used to produce polish and added badges. Eighteen karat gold with a high copper content is establish in some traditional jewelry and will have a distinct, though not dominant copper cast, giving an attractively warm color. A comparable karat weight when alloyed with silvery metals will appear less humid in color, and some low karat white metal alloys may be sold as "white gold", silvery in exterior with a slightly yellow cast but far more resistant to decay than silver or sterling silver. Karat weights of twenty and higher is more general in modern jewelry. Because of its high electrical conductivity and confrontation to decay and other desirable combinations of physical and chemical properties, gold also emerged in the late 20th century as an vital industrial metal, particularly as thin plating on electrical card associates and connectors.

Sunday, February 04, 2007

The Real Miracle

As far as Miracles is concern, turning salty seawater in to sweet water is quite amazing. Regardless of the scientific clarification being doled out—surplus freshwater flowing from the Mahim River into the sea—the thousand mass to Mahim Creek near the beachfront in Mumbai will pretty see the ‘transubstantiation’ as the deed of the late Haji Maqdoom Baba, whose shrine is in the area. Mass hysteria, of course, is only a term to clarify the hordes of believers filling plastic bottles and drinking the water. But the real miracle would be if those glugging the ‘miraculous’ water manages to flee succumbing to serious gastric illness.
The water of Mahim Creek, sweetened or otherwise, is dirty and would scandalize not only the likes of Sunita Narain of the Centre for Science and Environment. Maharashtra Chief Minister Vilasrao Deshmukh and officials of the Municipal Corporation of Greater Mumbai have already request to people not to drink the water. Industrial waste is not the finest ingredient for a miracle. But telling this to goggle-eyed people facing even more goggle-eyed TV cameras is as worthwhile as persuasive people that a Ganesh idol sipping milk is caused by suction and not godly lactose tolerance.
Fortunately, rumors of the sweetened water turning back to its original brackish form might stop a future surge. Now we only wait for the real miracle of no one complaining of sickness.