PVs can be used in a variety of applications. The simplest photovoltaic systems power small consumer goods such as calculators and wrist watches. Other applications include water pumps, street and car-park lighting, garden footpath lighting, etc. Some experimental cars also use PV cells. They convert sunlight directly into energy to power electric motors on the car. Solar photovoltaic panels are applied in satellites and spacecrafts as well.

The hidden factor behind the lack of widespread solar power production is the absence of mass consumer demand for solar technologies. If there is a demand for a product, there will be people that will supply that product at a cost that fulfills that demand. As a result, economic and efficient solar power technologies will be developed and exploit more quickly.

In 1472, he was accepted into the painter's guild of Florence and officially graduated from apprentice to master. After leaving Verrocchio's studio in 1478, Leonardo remained in Florence where he worked independently. His early paintings include Ginevra de Benu (1474), Adoration of the Magi (1481), Benois Madonna (1481), Saint Jerome (1481), and an altarpiece for the chapel of the Palazzo Vecchio. The unfinished Adoration of the Magi is the most important of all the early paintings.

In his lifetime, Leonardo began dozens of paintings, but abandoned the majority of them before they were completed, never returning to finish them. Many artists attest that this is not an occurrence unique to da Vinci, and that such abandonment stems from creative exhaustion. But psychologists and historians speculate that da Vinci's personality was simply too restless to complete many projects, most of which were started simultaneously and abandoned on a whim.

The breadth of his inventive prowess is astounding in light of his many other pursuits. Da Vinci designed or created devices that could immediately be employed in his own day, such as water pumps. He also drew up devices that are commonplace today, but would have been flights of fancy in his time, such as his design for a submarine. Based on the gear, he came up with loads of different ideas, including the bicycle and an "auto-mobile". He sketched designs of many different flying machines. Leonardo designed an flying machine that bears a striking resemblance to modern helicopters.

After the death of Giuliano dei Medici, Leonardo accepted an invitation from Francis I, king of France, to leave Italy and work for him. At the age of 67, in 1519, while living in France, Leonardo Da Vinci died and was buried in the church of Saint-Forentine in Amboise. The church was ruined during the French Revolution, and completely torn down during the 19th Century. And although today, there are no markings to identify Leonardo's grave, he continues to live on through his surviving paintings, his many notebooks and through the extensive selection of posters, stamps, and prints that have been produced over the years.

According to legend Oxford University was founded by King Alfred the Great in 872 when he happened to meet some monks there and had a scholarly debate that lasted several days. A more realistic scenario is that it grew out of efforts begun by Alfred to encourage education and establish schools throughout his territory.

From the start there was friction between "town and gown". Most students took lodgings with local people, who soon realised that they could charge high prices and rents of the Academics. However it was a strain on the resources of the community to have to provide for the influx of people from elsewhere. In the 13th century, rioting between students and localpeople hastened the establishment of primitive halls of residence. These were succeeded by the first of Oxford's colleges or endowed houses whose architectural splendour, together with the University's libraries and museums, give the city its unique character.

Today Oxford University is comprised of thirty-nine colleges and six permanent private halls, founded between 1249 and 1996, whose architectural grandeur, together with that of the University's libraries and museums, gives the city its unique character. More than 130 nationalities are represented among a student population of over 18,000. A range of scholarships offer support for international students.Thirty colleges and all halls admit students for both undergraduate and graduate degrees. Seven other colleges are for graduates only; one has Fellows only, and one specializes in part-time and continuing education. Each college is practically autonomous with its own set of rules. There is central administration, providing services such as libraries, laboratories, lectures and examination.

University of Cambridge is the second-oldest university in the English-speaking world (after Oxford). The start of the University is generally taken as 1209, when some masters and students arrived in Cambridge after fleeing from rioting in Oxford.

Cambridge University is more renowned than its rival for mathematics and natural sciences, and has produced 80 Nobel-prize winners (33 more than Oxford and the highest number of any university worldwide), 13 British Prime Ministers (12 less than the other place) and 8 Archbishops of Canterbury, among others.

The list of illustrious alumni is endless. Among the most famous are Desiderius Erasmus, Francis Bacon, Christopher Marlowe, Lord Byron, Charles Darwin, Ludwig Wittgenstein, Jawaharlal Nehru, Vladimir Nabokov, Lee Kuan Yew (PM of Singapore from 1959 to 1990), and Rajiv Gandhi. The great Russian scientist Pavlov came to Cambridge to receive the degree of the Honorary Doctor of Cambridge. University of Cambridge is known as a great centre of science, where many fomous scientists have worked.

Later, there were some people, who built snowboard like sleds. One of them was M.J. "Jack" Burchett. He cut out a plank of plywood in 1929 and tried to secure his feet with some clothesline and horse reins. Burchett came up with on of the first "snowboards".

Snowboarding continued to increase in popularity over the next years but for a long time, snowboarders were seen as society's outcasts. Ski resorts banned them and the upper-middle-class ski community looked down upon them. In 1985 snowboarding was only allowed in 7% of U. S. ski areas and story was much the same in Europe. As equipment and skill levels improved, though, snowboarding gradually became more acceptable. Most of the major ski areas had separate slopes for snowboarders by 1990. Now, about 97% of all ski areas in North America and Europe allow snowboarding and more than half of them have ramps and pipes. The number of snowboarders increased from about 2 million in 1990 to more than 7 million in 2000. It is predicted that the snowboarders will outnumber skiers by 2015.

The word "ski" is a Norwegian word which comes from the Old Norse word "skid", a board or a piece of split wood. The first hints to the existence of skis are on 4,500 to 5,000 years old rock carving at the Norwegian Island of Rodoy, showing a man on long runners with a hunting implement in hand. The oldest ski on record, being 1.10 m. long and 20 cm. broad was found in a peat bog in Hoting, Sweden and it is estimated to be about 4,500 years old. Several other skis have been found all throughout Scandinavia and Lapland. These ancient skis show regional differences in length and width, indicating a gradual refinement in technology.

Another illustrative example is found in Sweden history. In 1521 the Danes overran Sweden and massacred all the Swedish nobles but one, Gustav Vasa, who was able to escape. The Swedes were left without a leader, so two desparate peasants set out on skis to find Gustav. He came back, drove the Danes out of Sweden, and set up the kingdom that survives to this day.

When Europeans became aware of their Norwegian neighbors' amusement with skiing, the sport's popularity grew. By 1870, the skiing had spread to central Europe but soon became apparent that the techniques used by the Scandinavians were unsuitable for mountainous terrain, especially in the Alps of south central Europe. Nordic techniques were therefore adapted for the steeper slopes, and Alpine skiing was born.

The ski industry emerged and began in earnest after the Second World War, when Austria and Switzerland came out with the first Alpine Ski Resorts. The rapid advance of materials and technology further popularized the sport all over the world. Ski manufacturers developed faster and safer equipment which combined with the improving skills of the skiers to make the sport of skiing more intense, and easier to learn.

Nowadays, skiing has about 45 million fans worldwide. There are over 6,000 ski resorts around the world in more than 70 different countries. Most of these are in Europe, with 1,000 or so each in North America and Asia (Russia/Japan). Great ski resorts also exist in Chile, Argentina, Australia and New Zealand; they are found in hot countries such as Iran, Morocco, Lebanon, Greece, Turkey, Spain and Portugal; and since the end of the Cold War, East European countries such as Bulgaria and Romania, with their upgraded winter resorts provide excellent opportunities for ski enthusiasts of all levels.