RAINBOW                       


A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines on to droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun.
In a so-called "primary rainbow" ,the arc of a rainbow shows red on the outeR part of the arc, and violet on the inner section. This rainbow is caused by light being refracted then reflected once in droplets of water. In a double rainbow, a second arc may be seen above and outside the primary arc and has the order of its colours reversed. This second rainbow is caused by light reflecting twice inside water droplets. The region between a double rainbow is dark and is known as "Alexander's band" or "Alexander's dark band". The reason for this dark band is that, while light below the primary rainbow comes from droplet reflection and light above the upper rainbow also comes from droplet reflection, there is no mechanism for the region between a double rainbow to show any light reflected from water drops. It is impossible for an observer to manoeuvre to see any rainbow from water droplets at any angle other than the customary one (which is 42 degrees from the direction opposite the Sun). Even if an observer sees another observer who seems "under" or "at the end" of a rainbow, the second observer will see a different rainbow further off-yet, at the same angle as seen by the first observer. Thus, a "rainbow" is not a physical object and cannot be physically approached.

A rainbow spans a continuous spectrum of colours. The distinct bands are an artefact of human colour vision and no banding of any type is seen in a black-and-white photo of a rainbow. For colours seen by a normal human eye, the most commonly cited and remembered sequence, in English, is Newton's sevenfold violet, indigo, blue, green, yellow , orange and red  (popularly memorized as VIBGYOR). However, colour-blind persons will see fewer colors. Rainbows can be caused by many forms of airborne water. These include not only rain but also mist, spray and airborne dew.

Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind at a low altitude angle. The most spectacular rainbow displays happen when half the sky is still dark with raining clouds and the observer is at a spot with clear sky in the direction of the sun. The result is a luminous rainbow that contrasts with the darkened background. The rainbow effect is also commonly seen near waterfalls or fountains. In addition, the effect can be artificially created by dispersing water droplets into the air during a sunny day. Rarely, a moonbow, lunar rainbow or nighttime rainbow, can be seen on strongly moonlit nights. As human visual perception for colour is poor in low light, moonbows are often perceived to be white. It is difficult to photograph the complete semicircle of a rainbow in one frame, as this would require an angle of view of 84°. For a 35 mm camera, a lens with a focal length of 19 mm or less wide-angle lens would be required. Now that powerful software for stitching several images into a panorama is available, images of the entire arc and even secondary arcs can be created fairly easily from a series of overlapping frames. From an aeroplane, one has the opportunity to see the whole circle of the rainbow, with the plane's shadow in the centre. This phenomenon can be confused with the glory but a glory is usually much smaller, covering only 5–20°. At good visibility conditions, the second arc can be seen, with inverse order of colours. At the background of the blue sky, the second arc is barely visible.

          BIOSPHERE                         

The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system. From the broadest biophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, hydros  and atmosphere. The biosphere is postulated to have evolved, beginning through a process of biogenesis or biopoesis, at least some 3.5 billion years ago. In a broader sense, biospheres are any closed, self-regulating systems containing ecosystems including artificial ones such as Biosphere 2 and BIOS-3 and potentially, ones on other planets or moons.
Some life scientists and earth scientists use biosphere in a more limited sense. For example, geochemists define the biosphere as being the total sum of living organisms. In this sense, the biosphere is but one of four separate components of the geochemical model, the other three being lithosphere, hydrosphere and atmosphere. The narrow meaning used by geochemists is one of the consequences of specialization in modern science. Some might prefer the word ecosphere, coined in the 1960s, as all encompassing of both biological and physical components of the planet.

The Second International Conference on Closed Life Systems defined biospherics as the science and technology of analogs and models of Earth's biosphere i.e. artificial Earth-like biospheres. Others may include the creation of artificial non-Earth biospheres—for example, human-centered biospheres or a native Martian biosphere—in the field of biospherics. In the early 1970s, Lynn Margulis, a microbiologist from the United States, added to the hypothesis, specifically noting the ties between the biosphere and other Earth systems. For example, when carbon dioxide levels increase in the atmosphere, plants grow more quickly. As their growth continues, they remove more and more carbon dioxide from the atmosphere.
Many scientists are now involved in new fields of study that examine interactions between biotic and abiotic factors in the biosphere, such as geo-biology and geo-microbiology. Ecosystems occur when communities and their physical environment work together as a system. The difference between this and a biosphere is simple, the biosphere is everything in general terms.

Every part of the planet, from the polar ice caps to the Equator, supports life of some kind. Recent advances in microbiology have demonstrated that microbes live deep beneath the Earth's terrestrial surface and that the total mass of microbial life in so-called "uninhabitable zones" may, in biomass, exceed all animal and plant life on the surface. The actual thickness of the biosphere on earth is difficult to measure. Birds typically fly at altitudes of 650 to 1,800 meters and fish that live deep underwater can be found down to -8,372 meters in the Puerto Rico Trench. There are more extreme examples for life on the planet: Ruppell's Vulture has been found at altitudes of 11,300 meters. Bar-headed Geese migrate at altitudes of atleast 8,300 meters. Yaks live at elevations between 3,200 to 5,400 meters above sea level. Mountain goats live up to 3,050 meters. Herbivorous animals at these elevations depend on lichens, grasses and herbs.

Microscopic organisms live at such extremes that, taking them into consideration puts the thickness of the biosphere much greater. Culturable microbes have been found in the Earth's upper atmosphere as high as 41 km. It is unlikely, however, that microbes are active at such altitudes, where temperatures and air pressure are extremely low and ultraviolet radiation very high. More likely these microbes were brought into the upper atmosphere by winds or possibly volcanic eruptions. Barophilic marine microbes have been found at more than 10 km depth in the Marianas Trench. Microbes are not limited to the air, water or the Earth's surface. Culturable thermophilic microbes have been extracted from cores drilled more than 5 km into the Earth's crust in Sweden, from rocks between 65-75 °C. Temperature increases with increasing depth into the
Earth's crust. The speed at which the temperature increases depends on many factors, including type of crust, rock type, geographic location, etc. The upper known limit of temperature at which microbial life can exist is 122 °C and it is likely that the limit of life in the "deep biosphere" is defined by temperature rather than absolute depth.

Our biosphere is divided into a number of biomes, inhabited by broadly similar flora and Fauna. On land, biomes are separated primarily by latitude. Terrestrial biomes lying within the Arctic and Antarctic Circles are relatively barren of plant and animal life, while most of the more populous biomes lie near the equator. Terrestrial organisms in temperate and Arctic biomes have relatively small amounts of total biomass, smaller energy budgets and display prominent adaptations to cold, including world-spanning migrations, social adaptations, homeothermy, estivation and multiple layers of insulation.

      GEOMETRY

Geometry (Greek: Geo- "earth" -Metria "measurement") is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space. Geometry is one of the oldest mathematical sciences. Initially a body of practical knowledge concerning lengths, areas and volumes, in the 3rd century BC geometry was put into an axiomatic form by Euclid, whose treatment—Euclidean geometry—set a standard for many centuries to follow. Archimedes developed ingenious techniques for calculating areas and volumes, in many ways anticipating modern integral calculus. The field of astronomy, especially mapping the positions of the stars and planets on the celestial sphere and describing the relationship between movements of celestial bodies, served as an important source of geometric problems during the next one and a half millennia. A mathematician who works in the field of geometry is called a geometer. The introduction of coordinates by Rene Descartes and the concurrent development of algebra marked a new stage for geometry, since geometric figures, such as plane curves, could now be represented analytically, i.e., with functions and equations. This played a key role in the emergence of infinitesimal calculus in the Th century. Furthermore, the theory of perspective showed that there is more to geometry than just the metric properties of figures: perspective is the origin of projective geometry. The subject of geometry was further enriched by the study of intrinsic structure of geometric objects that originated with Euler and Gauss and led to the creation of topology and differential geometry.

In Euclid's time there was no clear distinction between physical space and geometrical space. Since the 19th-century discovery of non-Euclidean geometry, the concept of space has undergone a radical transformation and the question arose which geometrical space best fits physical space. With the rise of formal mathematics in the 20th century, also space lost its intuitive contents, so today we have to distinguish between physical space, geometrical spaces and abstract spaces. Contemporary geometry considers manifolds, spaces that are considerably more abstract than the familiar Euclidean space, which they only approximately resemble at small scales. These spaces may be endowed with additional structure, allowing one to speak about length. Modern geometry has multiple strong bonds with physics, exemplified by the ties between pseudo-Riemannian geometry and general relativity. One of the youngest physical  theories, string theory, is also very geometric in flavour. While the visual nature of geometry makes it initially more accessible than other parts of mathematics, such as algebra or number theory, geometric language is also used in contexts far removed from its traditional, Euclidean provenance.

Geometry originated as a practical science concerned with surveying, measurements, areas and volumes. Among the notable accomplishments one finds formulas for lengths, areas and volumes, such as Pythagorean theorem, circumference and area of a circle, area of a triangle, volume of a cylinder, sphere and a pyramid. A method of computing certain inaccessible distances or heights based on similarity of geometric figures is attributed to Thales. Development of astronomy led to emergence of trigonometry and spherical trigonometry, together with the attendant computational techniques.

                                           DEMOCRACY
     
Democracy is a form of government in which all people have an equal say in the decisions that affect their lives. Ideally, this includes equal participation in the proposal, development and passage of legislation into law. It can also encompass social, economic and cultural conditions that enable the free and equal practice of political self-determination. According to some theories of democracy, popular sovereignty is the founding principle of such a system. However, the democratic principle has also been expressed as "the freedom to call something into being which did not exist before, which was not given and which therefore, strictly speaking, could not be known." This type of freedom, which is connected to human "natality," or the capacity to begin anew, sees democracy as "not only a political system" an aspiration, really, intimately connected to and dependent upon a picture of what it is to be human—of what it is a human should be to be fully human."
While there is no universally accepted definition of 'democracy', equality and freedom have both been identified as important characteristics of democracy since ancient times. These principles are reflected in all citizens being equal before the law and having equal access to legislative processes. For example, in a representative democracy, every vote has equal weight, no unreasonable restrictions can apply to anyone seeking to become a representative and the freedom of its citizens is secured by legitimized rights and liberties which are generally protected by a constitution.

There are several varieties of democracy. Some of which provide better representation and more freedom for their citizens than others. However, if any democracy is not structured so as to prohibit the government from excluding the people from the legislative process or any branch of government from altering the separation of powers in its own favor, then a branch of the system can accumulate too much power and destroy the democracy. Representative Democracy, Consensus Democracy and Deliberative Democracy are all major examples of attempts at a form of government that is both practical and responsive to the needs and desires of citizens.
Many people use the term "democracy" as shorthand for liberal democracy, which may include elements such as political pluralism, equality before the law, the right to petition elected officials for redress of grievances, due process, civil liberties, human rights and elements of civil society outside the government. In the United States, separation of powers is often cited as a central attribute but in other countries such as the United Kingdom, the dominant principle is that of parliamentary sovereignty. In other cases, "democracy" is used to mean direct democracy. Though the term "democracy" is typically used in the context of a political state, the principles are applicable to private organizations and other groups as well.
Majority rule is often listed as a characteristic of democracy. However, it is also possible for a minority to be oppressed by a "tyranny of the majority" in the absence of governmental or constitutional protections of individual or group rights. An essential part of an "ideal" representative democracy is competitive elections that are fair both substantively and procedurally. Furthermore, freedom of political expression, freedom of speech and freedom of the press are considered to be essential, so that citizens are adequately informed and able to vote according to their own best interests as they see them. It has also been suggested that a basic feature of democracy is the capacity of individuals to participate freely and fully in the life of their society.
Democracy has its formal origins in Ancient Greece but democratic practices are evident in earlier societies including Mesopotamia, Phoenicia and India. Other cultures since Greece have significantly contributed to the evolution of democracy such as Ancient Rome, Europe and North and South America. The concept of representative democracy arose largely from ideas and institutions that developed during the European Middle Ages and the Age of Enlightenment and in the American and French Revolutions. Democracy has been called the "last form of government" and has spread considerably across the globe. The right to vote has been expanded in many jurisdictions over time from relatively narrow groups with New Zealand the first nation to grant universal suffrage for all its citizens in 1893. Democracy is often confused with the republic form of government.

Parliamentary democracy is a representative democracy where government is appointed by representatives as opposed to a 'presidential rule' wherein the President is both head of state and the head of government and is elected by the voters. Under a parliamentary democracy, government is exercised by delegation to an executive ministry and subject to ongoing review, checks and balances by the legislative parliament elected by the people. Parliamentary systems have the right to dismiss a Prime Minister at any point in time that they feel he or she is not doing their job to the expectations of the legislature. This is done through a vote of no Confidence where the legislature decides whether or not to remove the Prime Minister from office by a majority support for his or her dismissal. The Prime Minister can also call an election whenever he or she so chooses. Typically the Prime Minister will hold an election when he or she knows that they are in good favor with the public as to get re-elected.

           WINNERS vs LOSERS


The winner is a part of solution.                                  The loser is a part of the problem.


The winner has a plan.                                                   The Loser always has an excuse.


The winner says "It may be difficult".                         The loser says "Its impossible".


The winner makes commitments.                               The loser makes promises.


The winner has a dream.                                                The loser has schemes.


The winner sees gain.                                                      The loser sees the pain.


The winner says "Let me do it for you" .                       The loser says "That's not my job".


The winner says "I must do something"                The loser says "Something must be done"


The winner is a part of the team.                                   The loser is apart from the team.

                     ATM'S


An automated teller machine (ATM) also known as a Cash Point  is a computerised telecommunications device that provides the clients of a financial institution with access to financial transactions in a public space without the need for a cashier, human clerk or bank teller. ATMs are known by various other names including ATM Machine, automatic banking machine, cash machine and various regional variants derived from trademarks on ATM systems held by particular banks. Invented by IBM, the first ATM was introduced in December 1972 at Lloyds Bank in the UK. On most modern ATMs, the customer is identified by inserting a plastic ATM card with a magnetic stripe or a plastic smart card with a chip, that contains a unique card number and some security information such as an expiration date. Authentication is provided by the customer entering a personal identification number.

Using an ATM, customers can access their bank accounts in order to make cash withdrawals, credit card cash advances and check their account balances as well as purchase prepaid cellphone credit. If the currency being withdrawn from the ATM is different from that which the bank account is denominated in , the money will be converted at a wholesale exchange rate. Thus, ATMs often provide the best possible exchange rate for foreign travelers and are heavily used for this purpose as well.

The idea of self-service in retail banking developed through independent and simultaneous efforts in Japan, Sweden, the United Kingdom and the United States. In the USA, Luther George Simjian has been credited with developing and building the first cash dispenser machine. There is strong evidence to suggest that Simjian worked on this device before 1959 while his 132Nd patent was first filed on 30 June 1960. The rollout of this machine, called Bankograph, was delayed a couple of years. This was due in part to Simjian's Reflectone Electronics Inc. being acquired by Universal Match Corporation. An experimental Bankograph was installed in New York City in 1961 by the City Bank of New York but removed after 6 months due to the lack of customer acceptance. The Bankograph was an automated envelope deposit machine and it did not have cash dispensing features.

A first cash dispensing device was used in Tokyo in 1966. Although little is known of this first device, it seems to have been activated with a credit card rather than accessing current account balances. It was followed in 1967 by a machine in Uppsala.
ATMs are placed not only near or inside the premises of banks but also in locations such as shopping malls, airports, grocery stores, petrol stations, restaurants or anywhere frequented by large numbers of people. There are two types of ATM installations- on- and off-premise. On premise ATMs are typically more advanced, multi-function machines that complement a bank branch's capabilities and are thus more expensive. Off-premise machines are deployed by financial institutions and Independent Sales Organizations where there is a simple need for cash, so they are generally cheaper mono-function devices. In Canada, ABMs not operated by a financial institution are known as "White Label ABMs". In North America banks often have drive-through lanes providing access to ATMs. Many ATMs have a sign above them, called a topper, indicating the name of the bank or organization owning the ATM and possibly including the list of ATM networks to which that machine is connected.


Most ATMs are connected to interbank networks, enabling people to withdraw and deposit money from machines not belonging to the bank where they have their account or in the country where their accounts are held. Some examples of interbank networks include PULSE, PLUS, Interswitch, STAR and LINK.
ATM's rely on authorization of a financial transaction by the card issuer or other authorizing institution via the communications network. This is often performed through an ISO 8583 messaging system.

Many banks charge ATM usage fees. In some cases, these fees are charged solely to users who are not customers of the bank where the ATM is installed.

COAL (HOW IS IT FORMED)


Coal is a combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, with smaller quantities of sulfur, oxygen and nitrogen.


FORMATION OF COAL:-


Coal begins as layers of plant matter accumulating at the bottom of a body of water. For the process to continue, the plant matter must be protected from biodegradation and oxidization, usually by mud or acidic water. This traps their carbon in immense peat bogs that are eventually covered over and deeply buried by sediments. Under this compression the plant material is metamorphosed into coal. Over time, the chemical and physical properties of the plant remains are changed by geological action to create a solid material.
The wide shallow seas of the Carboniferous period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the Coal gap in the Lower Triassic, where coal is rare. Coal is even known from Precambrian strata, which predate land plants. This coal is presumed to have originated from algal residues. Coal, a fossil fuel, is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide anthropogenic sources of carbon dioxide releases. Gross carbon dioxide emissions from coal usage are slightly more than those from petroleum and about double the amount from natural gas. Coal is extracted from the ground by mining, either underground by shaft mining through the seams or in open pits.




TYPES OF COAL:-

1. Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions, for example, Ireland and Finland. In its dehydrated form, peat is a highly effective absorbent for fuel and oil spills on land and water.
2. Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Upper Palaeolithic.

3. Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal are used primarily as fuel for steam-electric power generation. Additionally, it is an important source of light aromatic hydrocarbons for the chemical synthesis industry.
4. Bituminous coal, dense sedimentary rock, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke.
5. Steam coal is a grade between bituminous coal and anthracite, once widely used as a fuel for steam locomotives. In this specialized use it is sometimes known as sea-coal in the U.S. Small steam coal was used as a fuel for domestic water heating.
6. Anthracite(the highest rank):- A harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically altered bituminous coal and petrified oil as from the deposits in Pennsylvania.

7. Graphite, technically the highest rank but difficult to ignite and is not so commonly used as fuel. It is mostly used in pencils and when powdered as a lubricant.

       HUMAN SKELETON

The human skeleton consists of both fused and individual bones supported and supplemented by ligaments, tendons, muscles and cartilage. It serves as a scaffold which supports organs, anchors muscles and protects organs such as the brain, lungs and heart. The biggest bone in the body is the femur in the thigh and the smallest is the stapes bone in the middle ear. In an adult, the skeleton comprises around 30-40% of the total body weight and half of this weight is water.
Fused bones include those of the pelvis and the cranium. Not all bones are interconnected directly: there are three bones in each middle ear called the ossicles that articulate only with each other. The hyoid bone, which is located in the neck and serves as the point of attachment for the tongue, does not articulate with any other bones in the body, being supported by muscles and ligaments. Early in gestation, a fetus has a cartilaginous skeleton from which the long bones and most other bones gradually form throughout the remaining gestation period and for years after birth in a process called endochondral ossification. The flat bones of the skull and the clavicles are formed from connective tissue in a process known as intramembranous ossification and ossification of the mandible occurs in the fibrous membrane covering the outer surfaces of Meckel's cartilages. At birth, a newborn baby has over 300 bones, whereas on average an adult human has 206 bones. The difference comes from a number of small bones that fuse together during growth, such as the sacrum and coccyx of the vertebral column.

The axial skeleton is formed by the Vertebral column, the Rib cage and the skull. The axial skeleton transmits the weight from the head, the trunk and the upper extremities down to the lower extremities at the hip joints and is therefore responsible for the upright position of the human body. Most of the body weight is located in back of the spinal column which therefore have the erectors spinae muscles and a large amount of ligaments attached to it resulting in the curved shape of the spine. The 366 skeletal muscles acting on the axial skeleton position the spine, allowing for big movements in the thoracic cage for breathing and the head. Conclusive research cited by the American Society for Bone Mineral Research demonstrates that weight-bearing exercise stimulates bone growth. Only the parts of the skeleton that are directly affected by the exercise will benefit. Non weight-bearing activity including swimming and cycling has no effect on bone growth.

There are many differences between the male and female human skeletons. Most prominent is the difference in the pelvis owing to characteristics required for the processes of childbirth. The shape of a female pelvis is flatter more rounded and proportionally larger to allow the head of a fetus to pass. Also the coccyx of a female's pelvis is oriented more inferiorly whereas the man's coccyx is usually oriented more anteriorly. This difference allows more room for a developing fetus. Men tend to have slightly thicker and longer limbs and digit bones, while women tend to have narrower rib cages, smaller teeth, less angular mandibles, less pronounced cranial features such as the brow ridges and external occipital protuberance and the carrying angle of the forearm is more pronounced in females. Females also tend to have more rounded shoulder blades.

KILLER WAVES - TSUNAMI

A tsunami at one time referred to as a tidal wave, is a series of water waves caused by the displacement of a large volume of a body of water, usually an ocean, though it can occur in large lakes. Tsunamis are a frequent occurrence in Japan, approximately 195 events have been recorded. Owing to the immense volumes of water and the high energy involved, tsunamis can devastate coastal regions. Earthquakes, volcanic eruptions and other underwater explosions glacier calvings and other mass movements, meteorite ocean impacts or similar impact events, and other disturbances above or below water all have the potential to generate a tsunami.

Some meteorological conditions, such as deep depressions that cause tropical cyclones can generate a storm surge called a meteotsunami, which can raise tides several metres above normal levels. The displacement comes from low atmospheric pressure within the centre of the depression. As these storm surges reach shore, they may resemble tsunamis, inundating vast areas of land. Tsunami can be generated when the sea floor abruptly deforms and vertically displaces the overlying water. Tectonic earthquakes are a particular kind of earthquake that are associated with the Earth's crustal deformation. When these earthquakes occur beneath the sea, the water above the deformed area is displaced from its equilibrium position. More specifically, a tsunami can be generated when thrust faults associated with convergent or destructive plate boundaries move abruptly, resulting in water displacement, owing to the vertical component of movement involved. Movement on normal faults will also cause displacement of the seabed, but the size of the largest of such events is normally too small to give rise to a significant tsunami.Tsunamis have a small amplitude offshore and a very long wavelength ,which is why they generally pass unnoticed at sea, forming only a slight swell usually about 12 inches above the normal sea surface. They grow in height when they reach shallower water, in a wave shoaling process described below. A tsunami can occur in any tidal state and even at low tide can still inundate coastal areas. On April 1, 1946, a magnitude 7.8 earthquake occurred near the Aleutian Islands, Alaska. It generated a tsunami which inundated Hilo on the island of Hawai with a 14 metres high surge. The area where the earthquake occurred is where the Pacific Ocean floor is subducting under Alaska. Examples of tsunami originating at locations away from convergent boundaries include Storegga about 8,000 years ago, Grand Banks 1929, Papua New Guinea 1998. The Grand Banks and Papua New Guinea tsunamis came from earthquakes which destabilized sediments, causing them to flow into the ocean and generate a tsunami. They dissipated before traveling transoceanic distances.

The cause of the Storegga sediment failure is unknown. Possibilities include an overloading of the sediments, an earthquake or a release of gas hydrates like methane. The 1960 Valdivia earthquake 9.5, 1964 Alaska earthquake 9.2, 2004 Indian Ocean earthquake 9.2 and 2011 Tohoku earthquake 9.0 are recent examples of powerful megathrust earthquakes that generated tsunamis that can cross entire oceans. Smaller 4.2 earthquakes in Japan can trigger tsunamis that can only devastate nearby coasts but can do so in only a few minutes.

                                                                          TEACHER'S DAY  

Teachers Day is celebrated as a tribute to the valuable contribution made by teachers to the society by imparting knowledge and enlightening and shaping the career of students. Celebration of Teachers Day is fairly popular in many countries across the world and is even acknowledged by UNESCO. For students, Teachers Day is an occasion to pay reverence and gratitude to teachers for their selfless effort in shaping their career and enriching the education system in the process. When is Teachers’ Day celebrated? The date for celebrating this special event varies from country to country across the world. In India, Teachers Day is celebrated on the 5th of September every year, whereas, China celebrates this event on 10th September every year. The celebration in each country is generally correlated to either significant personalities or achievements of milestone in the field of education. India celebrates Teachers Day on September 5 since 1962 as it is the birth anniversary of Dr Sarvapalli Radhakrishnan, a prominent thinker, philosopher and an educator.

Most of the schools and institutions make elaborate preparations for the celebrations. The ceremony usually kicks off with a warm Teachers Day speech paying respect and thanking teachers for their contribution. This is often followed by a range of colourful cultural programs, feast and other activities which make the event special and memorable.  A few traditional ways of celebrating the event include presenting colourful flowers, beautiful Teachers Day cards or gifts to the teacher as tokens of love and admiration. But students often try innovative ways and ideas to celebrate Teachers Day. Some rely on creative and attractive Teachers Day greeting cards adorned with captivating and touchy quotes and messages to convey the indebtedness unfailingly and also to capture the wonderful moments of the event. Others select lovely and popular Teachers Day quotes to convey their inner feeling of love for their teacher.  Sending animated or e-greeting card is also a rage in the contemporary times. Available absolutely free of cost, these Teachers Day Greetings e-cards have become a preferred way to send warm wishes and shower emotions on teachers. Another modern and popular mode of wishing teachers today is the Teachers Day SMS. The advantage of sending SMS is that the message reaches its destination promptly and rarely goes unnoticed. For the celebration of Teachers Day, the text messages are available in varied languages allowing users to send SMS according to his/her preferred language.
All of us have been students at some stage of our life and have benefited from our teachers. Celebration of Teachers Day 2011 is a wonderful opportunity especially for all of us to show our gratitude and appreciation to our teachers.




Oh teacher, Oh teacher!


My test isn't signed
Because somehow

My parents went blind
Now, don't say it's my fault,
They left their hands in the bank vault.

Oh teacher, Oh teacher
Do you know why
I was born without wings
And so cannot fly
Thus I am late
Didn't have breakfast,
So if you don't mind,
Pass me a plate.

Oh teacher, Oh teacher!
I've failed again
Please don't scold me,
Now you'll see why,
I was thinking about
Having an eagle's brain.

            DAM


A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are often used in conjunction with dams to generate electricity. A dam can also be used to collect water or for storage of water which can be evenly distributed between locations.The word dam can be traced back to Middle English and before that, from Middle Dutch, as seen in the names of many old cities. Early dam building took place in Mesopotamia and the Middle East. Dams were used to control the water level, for Mesopotamia's weather affected the Tigris and Euphrates rivers, and could be quite unpredictable.

The earliest known dam is the Jawa Dam in Jordan, 100 kilometres northeast of the capital Amman. This gravity dam featured a 4.5 m high and 1 m wide stone wall, supported by a 50 m wide earth rampart. The structure is dated to 3000 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, located about 25 km south of Cairo, was 102 m long at its base and 87 m wide. The structure was built around 2800 or 2600 B.C. as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. By the mid-late third century BC, an intricate water-management system within Dholavira in modern day India, was built. The system included 16 reservoirs, dams and various channels for collecting water and storing it.Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on a grand scale". Roman planners introduced the then novel concept of large reservoir dams which could secure a permanent water supply for urban settlements also over the dry season. Their pioneering use of water-proof hydraulic mortar and particularly Roman concrete allowed for much larger dam structures than previously built, such as the Lake Homs Dam, possibly the largest water barrier to that date and the Harbaqa Dam both in Roman Syria. The highest Roman dam was the Subiaco Dam near Rome. Its record height of 50 m remained unsurpassed until its accidental destruction in 1305.

Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of the other basic dam designs which had been unknown until then. These include arch-gravity dams, arch dams, buttress dams and multiple arch buttress dams, all of which were known and employed by the 2nd century AD. Roman workforces also were the first to build dam bridges, such as the Bridge of Valerian in Iran.
Eflatun Pınar is a Hittite dam and spring temple near Konya, Turkey. It's thought to be from the time of the Hittite empire between the 15th and 13 century BC.The Kallanai is constructed of unhewn stone, over 300 m long, 4.5 m high and 20 m wide, across the main stream of the Kaveri river in Tamil Nadu, South India. The basic structure dates to the 1st century AD. and is considered one of the oldest water-diversion or water-regulator structures in the world, which is still in use. The purpose of the dam was to divert the waters of the Kaveri across the fertile Delta region for irrigation via canals.It is considered to be the oldest dam still in use.
Du Jiang Yan is the oldest surviving irrigation system in China that included a dam that directed waterflow. It was finished in 251 B.C. A large earthen dam, made by the Prime Minister of Chu, Sunshu Ao, flooded a valley in modern-day northern Anhui province that created an enormous irrigation reservoir 100 km, a reservoir that is still present today.

In Iran, bridge dams such as the Band-e Kaisar were used to provide hydropower through water wheels, which often powered water-raising mechanisms. One of the first was the Roman-built dam bridge in Dezful, which could raise water 50 cubits in height for the water supply to all houses in the town. Also diversion dams were known. Milling dams were introduced which the Muslim engineers called the Pul-i-Bulaiti. The first was built at Shustar on the River Karun, Iran, and many of these were later built in other parts of the Islamic world. Water was conducted from the back of the dam through a large pipe to drive a water wheel and watermill. In the 10th century, Al-Muqaddasi described several dams in Persia. He reported that one in Ahwaz was more than 910 m long and that and it had many water-wheels raising the water into aqueducts through which it flowed into reservoirs of the city. Another one, the Band-i-Amir dam, provided irrigation for 300 villages.In the Netherlands, a low-lying country, dams were often applied to block rivers in order to regulate the water level and to prevent the sea from entering the marsh lands. Such dams often marked the beginning of a town or city because it was easy to cross the river at such a place, and often gave rise to the respective place names in Dutch.

For instance the Dutch capital Amsterdam started with a dam through the river Amstel in the late 12th century, and Rotterdam started with a dam through the river Rotte, a minor tributary of the Nieuwe Maas. The central square of Amsterdam, covering the original place of the 800 year old dam, still carries the name Dam Square or simply the Dam.French engineer Benoit Fourneyron developed the first successful water turbine in 1832. The era of large dams was initiated after Hoover Dam was completed on the Colorado River near Las Vegas in 1936. By 1997, there were an estimated 8,00000 dams worldwide, some 40,000 of them over 15 m high.

      REFRIGERATOR

A refrigerator referred to as a fridge is a common household appliance that consists of a thermally insulated compartment and a heat pump which transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room. Cooling is a popular food storage technique in developed countries and works by decreasing the reproduction rate of bacteria. The device is thus used to reduce the rate of spoilage of foodstuffs.
A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for perishable food storage is 3 to 5 °C. A similar device which maintains a temperature below the freezing point of water is called a freezer.The refrigerator is a relatively modern invention among kitchen appliances. It replaced the icebox, which had been a common household appliance for almost a century and a half prior. For this reason, a refrigerator is sometimes referred to as an icebox.
refrigerators keep things cold because of the nature of heat. The Second Law of Thermodynamics essentially states that if a cold object is placed next to a hot object, the cold object will become warmer and the hot object will become cooler. A refrigerator does not cool items by lowering their original temperatures; instead, an evaporating gas called a refrigerant draws heat away, leaving the surrounding area much colder. Refrigerators and air conditioners both work on the principle of cooling through evaporation.

A refrigerator consists of two storage compartments - one for frozen items and the other for items requiring refrigeration but not freezing. These compartments are surrounded by a series of heat-exchanging pipes. Near the bottom of the refrigerator unit is a heavy metal device called a compressor. The compressor is powered by an electric motor. More heat-exchanging pipes are coiled behind the refrigerator. Running through the entire system is pure ammonia, which evaporates at -32 Celsius. This system is closed, which means nothing is lost or added while it is operating. Because liquid ammonia is a powerful chemical, a leaking refrigerator should be repaired or replaced immediately. The refrigeration process begins with the compressor. Ammonia gas is compressed until it becomes very hot from the increased pressure. This heated gas flows through the coils behind the refrigerator, which allow excess heat to be released into the surrounding air. This is why users sometimes feel warm air circulating around the fridge. Eventually the ammonia cools down to the point where it becomes a liquid. This liquid form of ammonia is then forced through a device called an expansion valve. Essentially, the expansion valve has such a small opening that the liquid ammonia is turned into a very cold, fast-moving mist, evaporating as it travels through the coils in the freezer. Since this evaporation occurs at -32 degrees Celsius, the ammonia draws heat from the surrounding area. This is the Second Law of Thermodynamics in effect. Cold material, such as the evaporating ammonia gas, tend to take heat from warmer materials, such as the water in the ice cube tray.

As the evaporating ammonia gas absorbs more heat, its temperature rises. The cool ammonia still draws heat from the warmer objects in the fridge, but not as much as the freezer section. The ammonia gas is drawn back into the compressor, where the entire cycle of pressurization, cooling and evaporation begins.