Tuesday, September 25, 2007

Great Wall of China

The 'Great wall of China' was built 2000 years ago.  The construction is said to have begun from the 5th century B.C.  The construction of the wall spread over many dynasties and  across many years.  The Great Wall is the only longest human made structure. The wall spans to a distance of about 6,400 kms.    

The construction of the wall was begun by  Qin Shi Huangdi, the first emperor of China during the Qin (Ch'in) Dynasty . In Chinese the wall is called "Wan-Li Qang-Qeng".  The wall was built as a primary defense  against the nomadic tribes.  The king positioned armies near the wall to give warning signals about any attack.   The wall was initially constructed with earth and gravel.  As it was difficult to transport resources to build the wall local resources which were available were used.  Rocks were used near mountain ranges and earth and gravel in plains.  The wall got eroded in due course and was repaired and rebuilt several times by the ruling dynasties.

The present form of the Great Wall was done during the Ming dynasty.  The Ming were defeated by the Mongols in the northern border.  Hence to protect themselves the Ming adopted the strategy of building walls in the northern side.  The Ming construction was of higher quality as they used bricks and stones instead of earth.  The Ming also allocated ample resources to maintain the walls to withstand the frequent attacks. 

The wall was well equipped with watch towers at regular intervals.  The watch towers often housed weapons, food and army.  The steps that form the Great Wall of China are very steep and tall in some areas.  It is said that the Great Wall is visible from the earth's orbit.

Wednesday, September 19, 2007

Camel - Ship of the Desert

Camel is called the 'Ship of the desert'. Camels are friendly animals and the best suited to live in the desert.  They can travel very long distances. They can live without food and water for about 3-4 days time.  Their strength and endurance have made them valuable to the desert. 

There are two varities of camels the 'Arabian Camel which has a single hump and the Bacterian camel with the double hump.  Camel's milk is a wholesome food. The people in the desert consider camels's milk as a boon to them.  Camel meat is also a delicacy and is also known for its nutritive properties.

Camels are very tall animals.  They stand up to a height of more than 7 feet. Their height protects them from the heat reflection of the hot sand.  They have tear glands and long eyelashes to protect themselves from sand stroms.  Their feet are well padded and insulated to travel in the desert sands.  Their webbed toes prevent them from sinking into the sand. They are herbivorous.  They have a leathery mouth which is suitable to thorny food. Their capacity to recycle water from their bladder helps them to survive without drinking water for longer periods.  Energy producing fats are stored in the camel's hump.

Thursday, August 09, 2007

What are Mummies?

The Egyptians believed life after death.  Hence they adopted a method of embalming the dead bodies and preserving them in tombs along with the possessions of the dead like clothes food etc, this process of embalming is called mummification. The Egyptians believed that the mummified body was the home for this soul or spirit.  Mummification in ancient Egypt was a very long and expensive process. The embalmed bodies are called mummies. They drained the dead body completely of moisture and retained the dried form so theat it would not decay.  The procedure of embalming is a very long procedure.  This practice was followed in Egypt for  more than 2000 years.  The procedure adopted to embalm varied from century to century.  Usually this was done only for the royal family members.
The process of mummification almost took 70 days and this was carried out by special priests who had detailed knowledge of human body and were experts.  The first step which they did was to remove the vital organs like the brain, liver, lungs, stomach and put them into special jars called 'Canopic Jars'.  The brain was removed by a very critical operation else the face could get disfigured.  The other organs were removed by through a cut that was made in the left side of the abdomen.  The heart was left in place as it was considered the persons center of intelligence. 
The embalmers used 'Natron' which is a type of salt that has drying properties.  The bodies were immersed in Natron until all the mositure is removed. Packets of Natron are place in the insides of the body to ensure the insides are completely dry. They then did some filling to bring the body back to shape. The body was then wrapped with lots of linen, it is in this stage were the relatives and friends of the dead can donate linen for wrapping.  This procedure requires 100s of yards of linen and it took atleast fifteen days to complete wrapping.  Warm resin coating was used at stages of wrapping and wrapping was continued. 
The tomb preparation, decoration and collection of items for the dead are all done well in advance.  Once the wrapping is complete the priests perform some rituals at the tomb entrance and then put the mummy in a coffin and the tomb is sealed.

Sunday, July 15, 2007

Facts About the Moon

The Moon is the only natural satellite of Earth.  The Moon, has been known since time immemorial. It is the second brightest object in the sky after the Sun. As the Moon orbits around the Earth. I takes approximately one month to complete one rotation. The Moon is the only celestial body that humans have travelled to and landed on and have brought samples.  The Soviet spacecraft Luna 2 was the first one to land on the moon on the July 20, 1959.  Neil Armstrong became the first man to step onto the surface of the Moon On July 20, 1969.

By simply viewing through the naked eye one can see two major types of terrain: relatively bright highlands and darker plains. The Moon has no atmosphere. The lunar sky is always dark as the diffraction of light requires an atmosphere. Various samples obtained reveal that there are three types of Terrain on the moon, the Regolith, the maria, and the Terrae. 'Regolith is the outermost part, the relatively bright, heavily cratered highlands are called "Terrae" and the dark, lightly cratered  is called "Maria".

Meteorite impacts on the moon brought a variety of "exotic" rocks to the Moon.  The samples obtained produced many different rock types for study. The underlying crust was also thinned and cracked due to the impacts. Due to the lack atmosphere nor any water, the components in the soils do not weather chemically as they would on Earth. Rocks more than 4 billion years old still exist there, yielding information about the early history of the solar system that is unavailable on Earth.

The gravitational forces between the Earth and the Moon cause some interesting effects. The most obvious is the tides. The Moon's gravitational attraction is stronger on the side of the Earth nearest to the Moon and weaker on the opposite side. Since the Earth, and particularly the oceans, is not perfectly rigid it is stretched out along the line toward the Moon. From our perspective on the Earth's surface we see two small bulges, one in the direction of the Moon and one directly opposite. The effect is much stronger in the ocean water than in the solid crust so the water bulges are higher.

The Moon has no global magnetic field. But some of its surface rocks exhibit magnetism which indicates there could have been a global magnetic field early in the Moon's history. The Moon's surface is completely exposed to the solar wind and many ions form the solar wind have become embedded in the moon's Regolith.

Friday, July 06, 2007

Newton's Laws of Motion

Newton's laws of motion are three physical laws. These laws provide relationships between the forces acting on a body and the motion of the body.Newton's laws were first published together in his work Philosophiae Naturalis Principia Mathematica (1687). The laws form the basis for classical mechanics. Newton used them to explain many results concerning the motion of physical objects.

Newton's First Law of Motion:
Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Newton's Second Law of Motion:
The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.

Newton's Third Law of Motion:
For every action there is an equal and opposite reaction.

The first law is termed as the "Law of Inertia".  The second law aid in quantitative calculations of dynamics.  This law explains the velocity chnages that happen when a force is applied.  The third law exemplifies by what happens when we bounce a rubber ball on the ground it pushes back itself witht he same force in the opposite direction.

Tuesday, April 17, 2007

Akshaya Trithiya

'Atchayam' - Growing without becaoming empty.The third day of the lunar fortnight, which is called 'thritiya'. Thus the properous day ' Akshya trithiya '. Like any other thidhi we celebrate the trithiya of the growing phase of the moon. Many Indian women worship the Godess Lakshmi on this sacred day. Many of our puranas reveal prosperous instances that took place on this day.
The siddhas are said to move about the universe and bless the people. Its said that its good to perform charity on this day. There are certain rituals that have to be followed on this day. One should take oil bath and worship God and do some charity. Performing libations to our departed ancestors is considred to be fruitful on this day. It is believed that wealth will increase if one keeps money in the pooja and worships on this day.
Puranas say that it was on this day that Lord Krishna bestowed kuchela with boudless wealth when he came to meet him. Astronomers say that this is the day on which the sun and the moon are the brightest. This is also an auspicious day to start new ventures and purchases. Its also believed that if a person buys small amount of gold and keeps it in the pooja and wears it on this day, it will accumulate all throught the year. Its good to gift clothes and fruits on this day.

Tuesday, March 27, 2007

What is Heart Failure?

Heart failure is a condition due to the inability of the heart to pump oxygenated blood and essential substances to the body parts caused due to the weekness in its muscles. This is a serious medical illness, and requires critical care admission.

Surgical correction is required if the heart failure is due to vavular diseases. Some symptoms are Fatigue, breathlessness on exertion or swollen veins in the neck area, enlargement of the liver etc., Patients with advanced heart failure and severe pumping defect of left ventricle have to be treated with ventricular repair procedures or ventricular assist devices.
Some patients may develop a condition called stent thrombosis after agioplasty with stenting. This is due to improper dialation of stent or an uncovered dissected area where stenting was carried out. Some symptoms are chest pain and breathlessness. These patients may require hospitalisation and repeat agioplasty if necessary.

There are various types of stents available in the market. The cost of the stents depends on the brand, special features and stent designs.The cost also depends upon the older generation and newer generation manufactury.

Sunday, March 18, 2007

Longest River in the world -Nile

Nile- The longest river in the worl, flowing about 6677 km. The Nile gets its name from the Greek word "Nelios", meaning River Valley. Nile Valley is called the cradle of civilization. Nile is the main water resource for Egypt. The two main tributaries of the Nile River are the White Nile and the Blue Nile. Lake Victoria is the source of the White Nile and the Blue Nile begins in the Ethiopian Highlands. The two tributaries converge in Khartoum, the capital of Sudan where they form the Nile River. The Nile flows from the mountains in the south to the Mediterranean in the north. Egypt is called the gift of Nile.

Before the construction of the Aswan High Dam; the Nile rolled through a series of six rapids, called cataracts, between northern Sudan and southern Egypt. The construction of the dam has caused major changes in the flow of Nile. Lake Nasser is a man-made lake created by the construction of the Aswan High Dam, opened in 1971. The dam was built to regulate the flow of the Nile River.

The major cities that are located on the edge of the Nile and White Nile are: Cairo, Gondokoro, Khartoum, Aswan, Thebes/Luxor, Karnak, and the town of Alexandria lies near the Rozeta branch.The major dams on the Nile are Roseires Dam, Sennar Dam, Aswan High Dam, and Owen Falls Dam. Fishing is a main source of income and wealth for many who live on the banks if Nile. Each year thousands of tonnes of fish are caught. Many modern travelers to Egypt today take a Nile cruise as part of their package.

Monday, March 12, 2007

What is Metabolism?

The body gets the energy it needs from food through a process called metabolism. Metabolism means transformation. Metabolism is a collection of chemical reactions that takes place to transform the food we eat into the energy needed by the body to perform actions. Metabolism is a constant process that begins when we're conceived and ends when we die. It is a necessary function that allows our bodies to use food and other resources to maintain the working parts, repair damage, heal injury and rid the body of toxins. Apart from aiding in digestion Metabolism aids absorption of nutrients. The metabolic activity is mostly influenced by the nutrition intake, adequate hydration and physical activity. When any one of these is lacking, the metabolic rate decreases.
After we consume food, the molecules in the digestive system called enzymes break proteins down into amino acids, fats into fatty acids, and carbohydrates into simple sugars. These compounds are absorbed into the blood, which transports them to the cells. After they enter the cells, other enzymes act to speed up or regulate the chemical reactions involved with "metabolizing" these compounds. During these processes, the energy from these compounds can be released for use by the body or stored in body tissues, especially the liver, muscles, and body fat. In this way, the process of metabolism is really a balancing act involving two kinds of activities that go on at the same time - the building up of body tissues and energy stores and the breaking down of body tissues and energy stores to generate more fuel for body functions.

Metabolism is a complicated chemical process. A calorie is a unit that measures how much energy a particular food provides to the body. The body stores the energy initially in form of fat. If a person consumes too many calories and his physical activity is not enough to utilise the consumed amount the excess remains as fat in the body thus resulting in increase of weight. The basal metabolic rate, or BMR, is a measure of the rate at which a person's body "burns" energy, in the form of calories, while at rest. Low calorie dieting slows your metabolism, making it progressively more difficult to lose weight and keep it off.

Anabolism or constructive metabolism, supports the growth of new cells, the maintenance of body tissues, and the storage of energy for use in the future. During anabolism, small molecules are changed into larger, more complex molecules of carbohydrate, protein, and fat.
Catabolism or destructive metabolism, is the process that produces the energy required for all activity in the cells. In this process, cells break down large molecules to release energy. This energy release provides fuel for anabolism, heats the body, and enables the muscles to contract and the body to move. As complex chemical units are broken down into more simple substances, the waste products released in the process of catabolism are removed from the body through the skin, kidneys, lungs, and intestines.
Several of the hormones of the endocrine system are involved in controlling the rate and direction of metabolism. Thyroxine , a hormone produced and released by the thyroid gland, plays a key role in determining how fast or slow the chemical reactions of metabolism proceed in a person's body.
The pancreas secretes hormones that help determine whether the body's main metabolic activity at a particular time will be anabolic or catabolic. For example, after eating a meal, usually more anabolic activity occurs because eating increases the level of glucose - the body's most important fuel - in the blood. The pancreas senses this increased level of glucose and releases the hormone insulin , which signals cells to increase their anabolic activities.

Metabolic disorder is caused by an abnormal chemical reaction in the body's cells. Some metabolic diseases are inherited. These conditions are called inborn errors of metabolism.

Wednesday, February 07, 2007

All About Nobel Prize

Nobel Prize is name after the swedish chemist Alfred Nobel who invented the Dynamite. He was first awarded the prize five years after his death.

The Nobel Prize was initially awarded for subjects like Physics, Chemistry, Medicine, Literature and Peace. Later on Economics was also added.

These prizes are awarded to individuals only except the Peace Prize and each award is awarded to minimum three people in a year.

The first Nobel prizes were awarded to

Chemistry : Jacobus H' van't Hoff
Physics : Wilhelin C Rotgen
Medicine : Emil A Von Behring
Literature : Rene F A Sully Prudhomme
Peace : Jean H Dunant Frederic Passy.

Saturday, February 03, 2007

Story of Paper - Papyrus To Paper

The story of paper tracks down to 5000 years behind. Paper originated in Egypt. Egyptians wrote on materials made from Papyrus Reed. These were grown in the Nile Delta. The writing material was made by laying strips of the stem side by side and sticking them together.

Although Papyrus was prevalent in Egypt it did not reach Europe. The Europeans used the animal skins. This material was called parchment. This had many advantages over papyrus. The parchment was very flexible and did not crack. It could be folded and both sides of it could be cused for writing.

The Chinese official name Ts' Ai Lun made paper using a strange assortment of mulberry and bamboo fibers. This is the material we use today. The chinese guarded the secret of making paper for more than 1000 years. Unfortunately the Moors learnt this and spread it to Spain and Sicily. From there it spread throughout Europe and by the 1200 the paper mills had mushroomed in Italy.

The Paper gained its importance once Johannes Gutenberg invented the first mechanical printing press in 1455. From then on books were printed using the paper and demad for paper grew. Presently United States is the world's leading paper producer.

Thursday, January 11, 2007

What is Chlorophyll?

Chlorophyll is the green colouring of leaves which are vital to green plants. This helps the plants to make their food. This is also reponsible for the colours in plants such as red in carrots. Plants which have no chlorophyll depend on other plants for food and are called parasites.

Chlorophyll absorbs sunlight and uses its energy to synthesise carbohydrates from CO2 and water. During this process of photosynthesis, chlorophyll produces energy, in the form of carbohydrates, which will power all of the plant's essential growth and development.

Friday, January 05, 2007


Fungi respresent a very important part of the thallophytes, and are distinguished from the rest by many definite charateristics. They have no chlorophyll and no starch is present in their cells. They do not live on their own manufactured food, but rely on decaying plant or animal remains.

The fungi may be single celled plants such as yeast, which is used for baking bread abd brewing beer or can be multicelled such as mushrooms. In these more advanced forms the main part of the plant is an intricate web of threads known as hyhae, the whole web is called mycelium. This often lives underground or inside the host plant on which the fungus is living. The hyphae threads run about either in or between the cells of the plant and have the power of dissolving the cellulose of the cell walls and living on the contents.

The saprophytic ones act in a similar way on dead organic material and are not generally harmful to plants or animals. The parasites on the other hand cause man a great deal of trouble and expense in trying to get rid of them. Some fungi like 'Athelete's foot attack man. With the larger fungi, the hyphae sometimes come above the ground and form a special structure which can produce spores. This is the fruiting stage of the plant and the mushroom and toadstool are examples of this.

The hyhpae have another property which is important to the fungus and this is the formation of hard tuber like body called sclerotium which is capable of exsiting for a long time without growing. This stage makes it difficult to get rid of fungal infections for they can withstand all adverse treatments yet germinate at favourable conditions.

The fungi lack chlorophyll so they absorb carbohydrates from plants or animals on which they live. Like the animals they are dependent on green plants for their food and canot live without them.

What are Bryophytes?

These are the mosses and liverworts. Liverworts are plants requiring damp conditions and they are often found in shade by water or near ditches, where they make green growths on surface of the soil or on rocks. The flattish visible part of the plant is called the thallus and from its underside are produced simple root-like growths which anchor it to the ground.

Most liverworts can increase by sending out branches which eventually become detached from the main plant. They can also reproduce sexually and after the fertilisation of the egg a stalk is produced from the upper surface of the thallus. At the top of the stalk is a capsule containing spores which, when released to fall on a suitable place of growth, will produce a new generation of liverworts.

Wednesday, January 03, 2007


A calender is just a way to keep track of time. The 'Gregorian' calender is most used these days. In Indian history, we have used different types of calenders. For business and government purposes we use the 'Gregorian' calender but, when its time to celebrate holidays like Pongal and Eid other calenders are used.

The Islamic calender is a lunar calender. The lunar month is roughly the time moon takes to go around the earth. The Islamic Lunar calender is shorter than the 'Gregorian' calender by 11 days. This means that the month of Ramzan will be observed around 11 days earlier every 'Gregorian' calender.

Emperor Akbar used a combination of the Hindu and Muslim Calender. This calender counts dates begining with the birth of Christ as A.D and counts dates before the birth of Christ as B.C. These days, many modern historians use the letters C.E (common era) instead of A.D and letters B.C.E instead of B.C.