Waste disposal

مواضيع بكالوريا ( ملحق علمي)

Waste disposal

Every year people throw huge quantities of rubbish in their daily activities. People generate many types of waste including used paper, empty packages and food scraps. Homes, businesses and other places in the community produce substantial quantities of waste. To dispose of waste people either bury it, burn it or recycle it.

People often dispose of waste in open holes called open landfills, but they are dangerous because rainfall dissolves some of the chemicals from waste forming leachate which could pollute groundwater. Another type is called sanitary landfills which when full is covered by clay cap but they can also pollute the soil and groundwater. Another solution is solid waste composting which could reduce the volume of waste disposed of in sanitary landfills.

Incineration is the burning of solid waste in an incinerator which takes up less space and doesn't pollute groundwater and the heat produced can be used to generate electricity but incinerators release some pollution into the air and they cost much more money than landfills.

Recycling

Recycling is the process of reclaiming raw materials and reusing them again. Recycling reduces the volume of solid waste and saves the energy needed to obtain the raw materials. Common metals such as iron and aluminum can be melted down and reused. With recycling no ore needs to be mined, transported to factories and processed. Recycling metals also helps to conserve these nonrenewable resources.

Recycling glass is easy and inexpensive. It can be melted over and over again to make new glass containers. It can melt at a lower temperature than the raw materials. Therefore less energy is needed. Recycling glass also reduces the environmental damage caused by mining the raw materials.

We can also recycle used paper but each time paper is recycled, the new paper is rougher, weaker and darker. We can also recycle plastic which we get when oil is refined to get petrol and other products. When plastic is recycled, the new plastic can take very different forms such are carpeting, park benches. By recycling and reusing objects we can reduce pollution and the need for disposal sites.

The Future of the Internet

In the last thirty years the internet has grown dramatically. In 1983, there were only 200 computers connected to the internet; now there are around 50 million and this growth is going to continue.

Some specialists see our future in virtual reality – the use of computers with sounds and images that make you feel as if you are in a real situation. Virtual reality will become part of modern life. I think people will live and work in a virtual world . We will work in virtual offices, shop in virtual supermarkets, and we will even study in virtual schools and get all sorts of information from the internet.

The internet has transformed the way people communicate with each other and access information, and it continues to evolve everyday. It will be a low-costing network of billions of devices accessible to anyone everywhere. Some people fear that virtual reality will encourage people to opt out of human society, and that some will lose touch with reality of the real world.

The millennium bug

One of the most significant moments in IT history emerged at the close of the twentieth century when experts predicted that most computer system would malfunction at midnight on 31 January 1999. Computer scientists speculated that IT programs would stop working or produce incorrect result because they stored years with two digits instead of four – 98 instead of 1998, for example. They believed that the year 2000 would be represented by 00.This is known as the Millennium Bug, or the year 2000 problem.

They predicted that data systems in governments, banks and airports, would fail. When midnight arrived, the Millennium bug caused only minimal damage. Some Australian bus-ticket machines failed to work and some other small damages only happened.

The IT Age

IT, or Information Technology, is the foundation of our new world we live today. The term emerged in 1970s, but it can be traced to World War II, when the military and early computer specialists worked together to develop electronics, computers and information theory. In short, IT deals with the use of computers and computer software to convert, store, process, transmit and retrieve information.

In recent years the field has ballooned to include mobile telephones, computer games as well as ways of sharing, processing and storing information through the advance in computer applications and the internet. In a matter of decades, computers have developed from large machines to highly sophisticated devices that can fit in the palm of your hand.

Daily Life and Working Routine in Space

Now many people regularly travel into space facing extreme conditions and a tiny mistake can mean death. Life in space needs careful organization and planning. Daily life in space station needs a list of features , not just oxygen and heat. They also require the correct atmosphere. They need a mechanism for removing carbon dioxide which living things produce and a reliable means of day-t-to-day Living in microgravity (ways of eating, drinking and washing). Food, oxygen cylinders and fuels have to be prepared correctly. Sometimes work involves working outside the space station in a space suit.

They should carry out important work that could not be done on Earth. The International Space Station contains Laboratories where scientific experiments are carried out. Because they live in a small space, The astronauts carry out the cleaning in between their main duties.

They prepare food , maintain the systems on board and because there is no day and night in space. Sleep should be planned. They should allocate enough time to sleep and to keep fit they need two hours of exercise a day. Bones and muscles will become weak because there is no gravity .

Positive and Negative Effects of Caffeine on the Human Body

Caffeine is an odorless, slightly bitter solid. The most natural sources of caffeine are coffee, tea and cocoa. There is much debate about the health effects of caffeine. Caffeine is used as a stimulant of the heart and the nervous system in certain disorders. The stimulant effects of the caffeine are caused by a central nervous reaction . The heart rate increases , blood vessels expand and the brain receives more oxygen. This effect can last up to an hour. It make the person more alert and less sleepy. When taken in small amounts it increases the circulation and is considered harmless.

Caffeine may not be addictive in the classical sense, but the body build up tolerance over time. Some people find it difficult to function without at least one cup of strong coffee or tea in the morning. When taken in large amounts. It causes nervousness and loss of sleep, headache and digestive disturbances. The person who drinks caffeinated beverages in the morning only, may find themselves feeling more tired as the day progress.

How does the eye work ?

The eye is made up of several layers, each one playing a part in transforming the light that reflects off into images we can recognize. The amount of light that flows in through the pupil is controlled by tiny muscles around the iris. The lens focuses the rays of light so that when they strike the retina at the back of the eye they form a clear image. The retina is made of millions of rods and cones that detect the light, dismantle it and convert it into nerve impulses which travel along the optic nerve to the brain.

The brain then interprets the information and reconstructs it into a recognizable image . If any of these components do not function properly, or are not perfectly formed, a person's sight is impaired.