Friday, February 23, 2007

Erosion

Erosion is the displacement of solids by the agents of wind, water or ice, by downward or down-slope movement in response to gravity or by living organisms . Erosion is well-known from weathering, which is the decomposition of rock and particles through processes where no movement is caught up, although the two processes may be concurrent.
Erosion is an intrinsic normal process but in many places it is increased by human land use. Poor land use practices include deforestation, overgrazing, unmanaged construction movement and road or trail building. wever, improved land use practices can limit erosion, using techniques like terrace-building and tree planting.A certain amount of erosion is natural and, in fact, healthy for the ecosystem. For example,
gravels repeatedly move downstream in watercourses. Excessive erosion, however, can cause problems, such as in receipt of water sedimentation, ecosystem damage and outright loss of soil.

Monday, February 19, 2007

Magnetic field in Mercury planet

Despite its slow revolving, Mercury has a relatively strong magnetic field, with a magnetic field strength 1% as strong as the Earth’s. It is potential that this magnetic field is generated in a manner similar to Earth’s, by a dynamo of circulating liquid core material. However, scientists are uncertain whether Mercury’s core could still be liquid,although it could perhaps be set aside liquid by tidal effects during periods of high orbital eccentricity. It is also probable that Mercury’s magnetic field is a remnant of an earlier dynamo effect that has now ceased, with the magnetic field becoming “frozen” in solidified magnetic materials.
Mercury’s magnetic field is physically powerful sufficient to deflect the solar wind around the planet, that creates a magnetosphere within which the solar wind does not go through. This is in difference to the situation on the Moon, which has a magnetic field too weak to stop the solar wind impacting on its surface and so lacks a magnetosphere.

Wednesday, February 14, 2007

Fashion and the process of change

Fashion, by definition, changes regularly. The changes may proceed more quickly than in most other fields of human activities (language, thought, etc). For some, modern fast-paced changes in fashion embody many of the negative aspects of capitalism: it results in waste and encourages people qua regulars to buy things unnecessarily. Others, particularly young people, enjoy the diversity that varying fashion can it seems that provide, seeing the constant change as a way to satisfy their desire to experience "new" and "interesting" things. Note too that fashion can change to enforce uniformity, as in the case where so-called Mao suits became the national uniform of mainland China.At the same time there remains an equal or larger range designated (at least currently) 'out of fashion'. (These or similar fashions may cyclically come back 'into fashion' in due course, and remain 'in fashion' again for a while.).Practically every aspect of appearance has been changed at some time, for example skirt lengths ranging from ankle to mini to so short that it just covers anything, etc. In the past, new discoveries and lesser-known parts of the world could provide an impetus to change fashions based on the exotic: Europe in the eighteenth or nineteenth centuries, for example, might favor things Turkish at one time, things Chinese at another, and things Japanese at a third. The current version of exotic clothing includes club wear. Globalization has reduced the options of exotic novelty in more recent times, and has seen the introduction of non-Western wear into the Western world. Fashion houses and their connected fashion designers, as well as high-status consumers (including celebrities), appear to have some role in determining the rates and directions of fashion change.

Friday, February 09, 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.