E-MAIL

electronic mail, called e-mail was started in the late 1960's by the armed forces of the United States of America. The army or military officers were looking for a way that communications could be carried out in the event of a large-scale nuclear war. They needed a system would be very decentralized, reliable and fast in case central institutions were destroyed. They came up with e-mail.

In early 1970's, e-mail was limited to the US military, defense contractors and universities doing defence research. By the 1970's it had begun to spread more broadly within university communities. By the 1980's, academies in a number of university disciplines were using e-mail for professional collaboration.The early 1990'ssaw an exlpotion of the use of e-mail and other computer networkin g tools for a wide range of professional, academic and personal purposes. Whereas a few thousand people were using e-mail in 1980, it was estimated that in 2000, more then 25 million people throughout the world were using it.

E-mail is a wey of sending a message from one computer to one or more computrs around the world. First, you writedown the e-mail address of the person you're sending the message to. Then you compose the message, either by writing it directly in a special e-mail software program or by writing it first in a word-processing program, then transfering it into the e-mail software. You push a button to issue a simple command to send the message. The computer system you're connected to will break the message up into tiny pieces and send them electronically to the distination, usually over common telephone lines. The pieces might travel through different routes to various computers on the way. Then, usually within two or three minutes, the pieces will all arive at their distination, where
he receiving computer will re-assemble them into a message that can be read. The person receiving the message can then log into his or her computer account at a convenient time and read the mail.

FOLK LORE

One very important knowledge is folk lore.Lore means learning.Folk lore is the learning or knowledge that has not been written down.It has been passed down orally from generation to generation.what is interesting about folk lore ?while the main body of knowledge is passed down,the details may change from area to area.They are bound up with the customs and traditions of the society .It includes tales ,legends,oral history,proverbs,jokes and popular beliefs.

Every country has its own body of folk lore.Agricultural societies were full of folk lore.In Europe folk lore became a serious study in the 19th century with a rise of nationalism.Sociologists study folk lore.Jacob and Wihelm Grimm collected the stories and legends known in Germeny and compiled them as one book.The English translation is known as Children's and Household Tales.This was published in 1812.Now we can read lots of tales from all other lands.

When we read stories about these lands we can learn about the nature of the land,the climate,the animals and the living conditions of the time.There are many stories about fire in my lands.Alaadin stuck a match.That was magic.Amal Biso went to a house to borrow some fire/light.The story of the Little Match Girl tells us how she sold matches in the cold wintry evenings.

These stories influence our lives too.The popularity of the teddy bears comes from the love of the stories.The bears in these tales are like human beings,kind and gentle.This attitude to bears is totally absent in cultures.Sometimes a similar story may be told in two different lands.There is a story in Ummaga Jataka very similar to the story told by Bertolt Brecht in A Caucasian Chalk Circle.

Some habits customs and taboos,that is things you must not do,also are part of folk lore.The use of lime and turmeric for cleansing is one such example.In ancient times when a person died and the dead body was taken out,the place was sprinkled with turmeric water.People returning from a funeral would rub themseleves with time.It is known that lime and turmeric have disinfecting properties.In ancient times in Sri Lanka people going into forests,crossing onto an unknown land would break a sprig and hang it on a tree.It was considered as an offering to Aiiyanaka,a local god of the area.However the custom had a very significant use or meaning.The spirgs dying on these trees would indicate the path to the traveller.So, the belief that 'if you did not observe the rites of god Aiiyanayake you would be lost,has a real meaning.Perhaps the fear of god would have made people not to forget to take this very essential precaution.  

ECONOMIC RESOURCES.

Resources or inputs refer to anything provided by nature or previous generations that can be used directly or indirectly to satisfy human wants.Those resources can be classified as follows:

• Capital resources.
• Human resources.
• Natural resources.

Money is a tool for transferring resources , goods and services.Classical economics recognizes three catergories of resources as land,labour,and capital.Together with enterpreneurship,land,labour,capital viewed as the 4 factors of prodution in neoclassical economics.

01.Land.

Includes all natural resources and is viewed as both the site of production and the source of raw materials.Renewable resources such as forests,and fisheries can be replenished or produced relatively quickly.The highest rate at which a resource can be used sustainabily is the sustainable yield.Non-Renewable resources cannot be replenished once they are depleated[metallic minerals can be reused by recycling them,but coal and petroleum cannot be recycled].The payment for use and the received income of a land is rent.

02.Labour.

Consists of human effort provided in the creation of products paid in wage.Skills,energies,abilities,and knowledge that are used for the production of goods or the rentering of services.It is an inseperable,perishable factor and cannot be stored.

labour is an active factor of production  not like the other factors.As they are humanbeing this factor has its own feelings,like and dislikes,thinking power and it is a hetrogeneous factor.

03.Capital.

Consists of human made goods or means of production which is neded of the depreciation[Machinery,buildings and other infrastracture] in the other goods and services paid in interest.

04.Enterpreneurship.

Enterpreneurs serve as managers,risk taskers,leaders and visionaries.They bear the risk and income received by them profit.They are one of the human factor and gain profit in return of their services or work.

SOURCES OF KNOWLEDGE.

Books

Books are the most inportant sources of knowledege. We have learnt many things from books. As students, we love to read fair tales and other story books.

Now we have read stories, poems, histories, reports,biographies, adventures, everything in books. We have learnt about our country and other countries from books. We have read about things we have never seen or heard before.

Books give us not only knowlegde; give us entertainment too. The "Tales of the Arabian Nights", tell us of strange adventures. They keep us awake with curiosity. Aesop's Fables tell us of folktales of many lands. The fairy tales delighted us in our chidhood. Now we have the "Harry Potter" series. Sometimes back we had the Enid Blyton stories. Sometime back we had the Enid Blyton stories.

Each religion has its own books too.the christians have the Bible,the Muslims have the Quran,the Hindus have the Vedas,the buddhists have the Dammapada.The Mahavamsa is considered  the oldest record of history of our country.

When we are free,we spend our time with books in the library.When we are ill,and inbed how would we spend our time if we didnot have a storybook?Books and knowledge are inseperable in our life.

Encyclopaedia.

The word "encyclopaedia",comes from the classical Greek word meaning,'a general education'.The idea of producing an encyclopaedia is very old.The term was first used in 1541.

The encyclopaedia has developed from the dictionary in the 18th century. A dictionary is mainly on words and their definitions.it provides limited information,for the word defined.Sometimes the definition given in the dictionary may not given enough understanding of the words to the reader.He mey not understand the meaning,or significance of the world.he may not understand the broad meaning.

On the other hand it gives a full account on the subject.it gives the most relevent knowledge gathered on the subject.It often includes maps,illustrations,charts,as well as ststistics to show relationships.It is an ocmplete summary of information.This information can be on all branches of knowledge or a particular branch of knowledge.

Historical Ruins.

Historical Ruins provide alot of knowledge about the country.Sometimes these hitorical ruins are not properly understood,or interpreated.There are some ruins about which there are no records.Stone Henge of Wales is one such ruin.Still people donot know what it could have been.Some people think it may have been associated with the worship of the sun.

Some Henge is a popular decoration!Many computer users have the Stone Henge as a wall paper.There is also the massive stone pillar on the banks of the river Thames.This is known as Cleopatra'sNeedle!The totem poles of aborigines of Africa can be seen in the British Museum.For a long time the Sinhala crown and throne were kept in Britin They were returned when we got independence.

We can get an idea of the arts and crafts of the time from these ruins.We can learn about a country too from these ruins,They are an interesting source of knowledge.

NON VERBAL COMMUNICATION

All of us communicate verbally as well as non-verbally. If irritated, we may tense our bodies, press our lips together, and gesture with our eyebrows. With a gaze, a glenze or stare we can communicate intimacy, submission, or dominance.

Most of us are good at"reading" non-varbal cues to understand the emotions in an old silent fikm. We are especially good at detecting non-verbal threats. In a crowd of faces, single face will "pop out"fasetr than a single happy one. Some of us are more sensitive to these cues than others.

Robert Roasantheal and colleaggues discovered this by showing hundreds of people in brief film clips of portions of a person's emotionally expressive face or body, sometimes with a garbled voice added. For example, after a two second scene revealing only the face of an upset woman, the researchers would ask whether the woman was expressing anger or discussing a divorce. Rosenthal and company reported that some people are much better 'emotions detectors' than others, and that women were better at it that men.

The growing awareness that we communicate through the body's silent language has led to studies of how job applicants and interviewers communcation (or miscommunicate). There has also been a spate of guide business deal or selling a product, it pays to be ale to "read" feelings. Fidgeting for example, may reveal anxiety or boredom. Different expressions may convey the same emotions; either a cold stare or the avoidance of eye contact may signify hospitality. A given expression can also convey vary different emotions: folded arms, for example, can signify irritaton or relaxation.

MICROSCOPES IN RELATION TO CELLS

The invention of light microscope led to the discovery of cells. The electron microscope has revealed the fascinating world inside the cell and opened up the study of cell biology.the first commercial instrument was built in 1938. It was used to tsudy metals. Later, biologhists found to their surprise that the electron beam did not destroy biological speciments. The powerful new microscope opened up a new world. It revealed cell structures whitch no-one had ever  seen before. The science of cell biology took off.

Optical Microscope

Most cells are too small to be seen with the nacked eye. Without microscopes, we should know very little about  them. The photographs(called photomicrographs)are images of plant cells and animal cells seen through the micrographs. A lamp lights the specimen of cells which the observer views through two magnifying lenses. The magnification of the cell is worked out as:

Total magnification of cells = magnifying power of the eye piece lens x magnifying power of the objective lens.

Good quality optical microscopes can magnify cells up to 2000times (x 2000)their original size. At higher magnification, the miage is enlarged but less clear because together the eye piece lens and objective lens of the micrscope can not distinguish between cell structures lying side-by-side-the syructures blur together appearing as one fuzzy image. The ability of amicroscope to distinguish between structures lying close together is called resolving power.

Instead of a beam of light, it passses a beam of electrons through the speciman of the cells. It can magnify uo to 1 million times (x 1000000), producing images which show the structures of cells in minute detail. Such detail is possible because the resolving power of the transmission electron microscope is much greater then that of the optical microscope.

Electron Microsocope

One way to increase resolution is to increase magnification, so that small objects appear larger. Robert Hooke and Antonie van Leeuwenhoek were able to see small cells by magnifying their size, so that the cells appeared larger then the 100-micrometer limit imposed by human eye. Hooke and Leeuwenhoek accomplished this feat with microscopes that magnified images of cells by bending light through a glass lens. The size of the image that falls on the sheet of detector cells lining the back of your eye depends on how close the objects is to your eye - the closer the object, the bigger the image. Your eye, however, is incapable of focusing comfortably on an object closer then about 25 centimeters, because the eye is limited by the thickness of its lens.

Image of a cancer cell under microscope