Disease and ill health are caused largely by damage at the molecular and cellular level. Today's surgical tools are, at this scale, large and crude. From the viewpoint of a cell, even a fine scalpel is a blunt instrument more suited to tear and injure than heal and cure. Modern surgery works only because cells have a remarkable ability to regroup, bury their dead and heal over the injury.
Nanotechnology, "the manufacturing technology of the 21st century," should let us economically build a broad range of complex molecular machines (including, not incidentally, molecular computers). It will let us build fleets of computer controlled molecular tools much smaller than a human cell and built with the accuracy and precision of drug molecules. Such tools will let medicine, for the first time, intervene in a sophisticated and controlled way at the cellular and molecular level. They could remove obstructions in the circulatory system, kill cancer cells, or take over the function of subcellular organelles. Just as today we have the artifical heart, so in the future we could have the artificial mitochondrion.
Equally dramatic, nanotechnology will give us new instruments to examine tissue in unprecedented detail. Sensors smaller than a cell would give us an inside and exquisitely precise look at ongoing function. Tissue that was either chemically fixed or flash frozen could be analyzed literally down to the molecular level, giving a completely detailed "snapshot" of cellular, subcellular and molecular activities.
1. Introduction
There is broad agreement (though not consensus) that we will at some point in the future be able to inexpensively fabricate essentially any structure that is consistent with chemical and physical law and specified in molecular detail[REF04, REF06, REF07, REF08, REF18, REF21, REF22, REF30]. The most direct route to achieving this capability involves positioning and assembling individual atoms and molecules in a fashion conceptually similar to snapping together LEGO blocks. By designing and building programmable self replicating manufacturing systems[REF10, REF18, REF30, REF27, REF28] that incorporate these principles we should be able to achieve very low manufacturing costs. While the design and development of such programmable self replicating molecular manufacturing systems will be a major task and will likely require many years or a few decades, it appears that this kind of capability, to quote Feynman[REF08], "...cannot be avoided."
Design concepts for general purpose self replicating manufacturing systems have been discussed for many years [REF10, REF27, REF28], and their utility in manufacturing has been emphasized recently [REF04, REF05, REF06, REF18, REF30]. These proposals draw on a body of work started by von Neumann[REF27]. A wide range of methods have been considered[REF10, particularly pages 190 et sequitur "Theoretical Background"]. The von Neumann architecture for a self replicating system is the ancestral and archetypal proposal[REF24, REF27].
2. The von Neumann architecture for a general manufacturing system
Von Neumann's proposal consisted of two central elements: a universal computer and a universal constructor (see figure 1). The universal computer contains a program that directs the behavior of the universal constructor. The universal constructor, in turn, is used to manufacture both another universal computer and another universal constructor. Once construction is finished the program contained in the original universal computer is copied to the new universal computer and program execution is started.
Figure 1.
Von Neumann worked out the details for a constructor that worked in a theoretical two-dimensional cellular automata world (parts of his proposal have since been modeled computationally[REF24]). The constructor had an arm which it could move about and which could be used to change the state of the cell at the tip of the arm. By progressively sweeping the arm back and forth and changing the state of the cell at the tip, it was possible to create "objects" consisting of regions of the two-dimensional cellular automata world which were fully specified by the program that controlled the constructor.
While this solution demonstrates the theoretical validity of the idea, von Neumann's kinematic constructor (which was not worked out in such detail) has had perhaps a greater influence, for it is a model of general manufacturing which can more easily be adapted to the three-dimensional world in which we live. The kinematic constructor was a robotic arm which moved in three-space and which grasped parts from a sea of parts around it. These parts were then assembled into another kinematic constructor and its associated control computer.
An important point to notice is that self replication, while important, is not by itself an objective. A device able to make copies of itself but unable to make anything else would not be very valuable. Von Neumann's proposals centered around the combination of a universal constructor, which could make anything it was directed to make, and a universal computer, which could compute anything it was directed to compute. It is this ability to make any one of a broad range of structures under flexible programmatic control that is of value. The ability of the device to make copies of itself is simply a means to achieve low cost, rather than an end in itself.
3. Drexler's architecture for an assembler
Drexler's assembler follows the von Neumann kinematic architecture, but is specialized for dealing with systems made of atoms. The essential components in Drexler's assembler are shown in figure 2. The emphasis here (in contrast to von Neumann's proposal) is on small size. The computer and constructor both shrink to the molecular scale, while the constructor takes on additional detail consistent with the desire to manipulate molecular structures with atomic precision. The molecular constructor has two major subsystems: (1) a positional capability and (2) the tip chemistry.
Figure 2.
The positional capability might be provided by one or more small robotic arms, or alternatively might be provided by any one of a wide range of devices that provide positional control[REF09, REF15, REF25]. The emphasis, though, is on a positional device that is very small in scale: perhaps 0.1 microns (100 nanometers) or so in size.
The tip chemistry is logically similar to the ability of the von Neumann universal constructor to alter the state of a cell at the tip of the arm, but now the change in "state" corresponds to a change in molecular structure. That is, we must specify a set of well defined chemical reactions that take place at the tip of the arm, and this set must be sufficient to allow the synthesis of the structures of interest.
It is worth noting that current methods in computational chemistry are sufficient to model the kinds of structures that will appear in a broad class of molecular machines, including all of the structures and reactions needed for some assemblers[REF16, REF20, REF21, REF22]
4. Size of devices
Drexler's proposal for molecular mechanical logic [REF06] is the most compact and, from the system point of view, the best worked out. The logic elements ("locks," roughly the equivalent of a single transistor) need occupy a volume of only a few cubic nanometers. Even including system overhead (power, connections, etc). the volume per element should still be less than 100 cubic nanometers. A 10,000 element logic system (enough to hold a small processor) would occupy a cube no more than 100 nanometers on a side. That is, a volume only slightly larger than 0.001 cubic microns would be sufficient to hold a small computer. This compares favorably with the volume of a typical cell (thousands of cubic microns) and is even substantially smaller than subcellular organelles. Operating continuously at a gigahertz such a computer would use less than 10^-9 watts. By comparison, the human body uses about 100 watts at rest and more during exercise. Slower operation and the use of reversible logic would reduce power consumption, quite possibly dramatically[REF19, REF31].
A variety of molecular sensors and actuators would also fit in such a volume. A molecular "robotic arm" less than 100 nanometers long should be quite feasible, as well as molecular binding sites 10 nanometers in size or less.
By contrast, a single red blood cell is about 8 microns in diameter (over 80 times larger in linear dimensions than our 100 nanometer processor). Devices of the size range suggested above (~0.1 microns) would easily fit in the circulatory system and would even be able to enter individual cells.
5. An application: killing cancer cells
Given such molecular tools, we could design a small device able to identify and kill cancer cells. The device would have a small computer, several binding sites to determine the concentration of specific molecules, and a supply of some poison which could be selectively released and was able to kill a cell identified as cancerous.
The device would circulate freely throughout the body, and would periodically sample its environment by determining whether the binding sites were or were not occupied. Occupancy statistics would allow determination of concentration. Today's monoclonal antibodies are able to bind to only a single type of protein or other antigen, and have not proven effective against most cancers. The cancer killing device suggested here could incorporate a dozen different binding sites and so could monitor the concentrations of a dozen different types of molecules. The computer could determine if the profile of concentrations fit a pre-programmed "cancerous" profile and would, when a cancerous profile was encountered, release the poison.
Beyond being able to determine the concentrations of different compounds, the cancer killer could also determine local pressure. A pressure sensor little more than 10 nanometers on a side would be sufficient to detect pressure changes of less than 0.1 atmospheres (a little over a pound per square inch. See, for example, the discussion on page 472 et sequitur of Nanosystems[REF06] for the kind of analysis involved. One atmosphere is ~10^5 Pascals, so PV in this case would be (0.1 x 10^5 ) x (10^-8)^3 or 10^4 x 10^ -24 or 10^-20 joules. Multiple samples would be required to achieve reliable operation, as kT is ~4 x 10^-21 joules at body temperature. Linear increases in sensor volume would produce exponential increases in immunity to thermal noise and linear improvements in pressure sensitivity if that were to prove useful. Doubling the linear dimensions of the sensor would produce an eight-fold increase in both volume and pressure sensitivity).
As acoustic signals in the megahertz range are commonly employed in diagnostics (ultrasound imaging of pregnant women, for example), the ability to detect such signals would permit the cancer killer to safely receive broadcast instructions. By using several macroscopic acoustic signal sources, the cancer killer could determine its location within the body much as a radio receiver on earth can use the transmissions from several satellites to determine its position (as in the widely used GPS system). Megahertz transmission frequencies would also permit multiple samples of the pressure to be taken from the pressure sensor, as the CPU would be operating at gigahertz frequencies.
The cancer killer could thus determine that it was located in (say) the big toe. If the objective was to kill a colon cancer, the cancer killer in the big toe would not release its poison. Very precise control over location of the cancer killer's activities could thus be achieved.
The cancer killer could readily be reprogrammed to attack different targets (and could, in fact, be reprogrammed via acoustic signals transmitted while it was in the body). This general architecture could provide a flexible method of destroying unwanted structures (bacterial infestations, etc).
6. An application: providing oxygen
A second application would be to provide metabolic support in the event of impaired circulation. Poor blood flow, caused by a variety of conditions, can result in serious tissue damage. A major cause of tissue damage is inadequate oxygen. A simple method of improving the levels of available oxygen despite reduced blood flow would be to provide an "artificial red blood cell." We will consider a simple design here: a sphere with an internal diameter of 0.1 microns (100 nanometers) filled with high pressure oxygen at ~1,000 atmospheres (about 10^8 pascals). The oxygen would be allowed to trickle out from the sphere at a constant rate (without feedback). Diamond has a Youngs modulus of about 10^12 pascals. An atomically precise diamondoid structure should be able to tolerate a stress of greater than 5 x 10^10 pascals (5% of the modulus). Thus, a 0.1 micron sphere of oxygen at a pressure of 10^8 pascals could be contained by a hollow diamondoid sphere with an internal diameter of 0.1 microns and a thickness of less than one nanometer.
This thickness, thin as it is, results in an applied stress on the diamond of well under 1% of its modulus -- from a purely structural point of view we should be able to use a very large "bucky ball," i.e., a sphere whose surface is a single layer of graphite. Perhaps the most complex issue involved in the selection of the material is the reaction of the body's immune system. While some suitable surface structure should exist which does not trigger a response by the immune system -- after all, there are many surfaces in the body that are not attacked -- the selection of a specific surface structure will require further research. To give a feeling for the range of possible surface structures, the hydrogenated diamond (111) surface could have a variety of "camouflauge" molecules covalently bound to its surface. A broad range of biological molecules could be anchored to the surface, either directly or via polymer tethers.
The Van der Waals' equation of state is (p+a/v^2) (v-b) = RT, where p is the pressure, v is the volume per mole, R is the universal gas constant, T is the temperature in Kelvins, and a and b are constants specific to the particular gas involved. For oxygen, a = 1.36 atm liter^2/mole^2 and b = 0.03186 liter/mole and R = 0.0820568 liter-atmospheres/mole-kelvin. A mole of oxygen at 1,000 atmospheres and at body temperature (310 Kelvins) occupies 0.048 liters, or about 21 moles/liter. A mole of oxygen at 1 atmosphere and 310 Kelvins occupies 25.4 liters, or about 0.04 moles/liter. This implies a compression of ~530 to 1. A resting human uses ~240 cc/minute[REF32] of oxygen, so a liter of oxygen compressed to 1,000 atmospheres should be sufficient to maintain metabolism for about 36 hours (a day and a half). It might be desirable to replace less than a liter of blood with our microspheres of compressed oxygen, but it should still be quite feasible to provide oxygen to tissue even when circulation is severely compromised for periods of at least many hours from a single infusion.
Controlled release of oxygen from the diamondoid sphere could be done using the selective transport method proposed by Drexler[REF06] and illustrated in figure 3. Figure 3 shows transport in the "wrong" direction (for this application), but simply reversing the direction of rotor motion would result in transport from inside the reservoir to the external fluid. By driving a rotor at the right speed, oxygen could be released from the internal reservoir into the external environment at the desired rate.
Figure 3.
More sophisticated systems would release oxygen only when the measured external partial pressure of oxygen fell below a threshold level, and so could be used as an emergency reserve that would come into play only when normal circulation was (for some reason) interupted.
Full replacement of red blood cells would involve the design of devices able to absorb and compress oxygen when the partial pressure was above a high threshold (as in the lungs) while releasing it when the partial pressure was below a lower threshold (as in tissues using oxygen). In this case, selective transport of oxygen into an internal reservoir (by, for example, the method shown in Figure 3) would be required. If a single stage did not provide a sufficiently selective transport system, a multi-staged or cascaded system could be used. Compression of oxygen would presumably require a power system, perhaps taking energy from the combustion of glucose and oxygen (thus permitting free operation in tissue). Release of the compressed oxygen should allow recovery of a significant fraction of the energy used to compress it, so the total power consumed by such a device need not be great.
If the device were to simultaneously absorb carbon dioxide when it was present at high concentrations (in the tissue) and release it when it was at low concentrations (in the lungs), then it would also provide a method of removing one of the major products of metabolic activity. Calculations similar to those given above imply a human's oxygen intake and carbon dioxide output could both be handled for a period of about a day by about a liter of small spheres.
As oxygen is being absorbed by our artificial red blood cells in the lungs at the same time that carbon dioxide is being released, and oxygen is being released in the tissues when carbon dioxide is being absorbed, the energy needed to compress one gas can be provided by decompressing the other. The power system need only make up for losses caused by inefficiencies in this process. These losses could presumably be made small, thus allowing our artificial red blood cells to operate with little energy consumption.
By comparison, a liter of blood normally contains ~0.2 liters of oxygen[REF32, page 1722], while one liter of our spheres contained ~530 liters of oxygen (where "liter of oxygen" means, as is common in the literature on human oxygen consumption, one liter of the gas under standard conditions of temperature and pressure). Thus, our spheres are over 2,000 times more efficient per unit volume than blood; taking into account that blood is only about half occupied by red blood cells, our spheres are over 1,000 times more efficient than red blood cells.
Failure of a 0.1 micron sphere would result in creation of a bubble of oxygen less than 1 micron in diameter. Occasional failures could be tolerated. Given the extremely low defect rates projected for nanotechnology, such failures should be very infrequent.
7. An application: artificial mitochondria
While providing oxygen to healthy tissue should maintain metabolism, tissues already suffering from ischemic injury (tissue injury caused by loss of blood flow) might no longer be able to properly metabolize oxygen. In particular, the mitochondria will, at some point, fail. Increased oxygen levels in the presence of nonfunctional or partially functional mitochondria will be ineffective in restoring the tissue. However, more direct metabolic support could be provided. The direct release of ATP, coupled with selective release or absorption of critical metabolites (using the kind of selective transport system mentioned earlier), should be effective in restoring cellular function even when mitochondrial function had been compromised. The devices restoring metabolite levels, injected into the body, should be able to operate autonomously for many hours (depending on power requirements, the storage capacity of the device and the release and uptake rates required to maintain metabolite levels).
8. Further possibilities
While levels of critical metabolites could be restored, other damage caused during the ischemic event would also have to be dealt with. In particular, there might have been significant free radical damage to various molecular structures within the cell, including its DNA. If damage was significant restoring metabolite levels would be insufficient, by itself, to restore the cell to a healthy state. Various options could be pursued at this point. If the cellular condition was deteriorating (unchecked by the normal homeostatic mechanisms, which presumably would cease to function when cellular energy levels fell below a critical value), some general method of slowing further deterioration would be desirable. Cooling of the tissue, or the injection of compounds that would slow or block deteriorative reactions would be desirable. As autonomous molecular machines with externally provided power could be used to restore function, maintaining function in the tissue itself would no longer be critical. Deliberately turning off the metabolism of the cell to prevent further damage would become a feasible option. Following some interval of reduced (or even absent) metabolic activity during which damage was repaired, tissue metabolism could be restarted again in a controlled fashion.
It is clear that this approach should be able to reverse substantially greater damage than can be dealt with today. A primary reason for this is that autonomous molecular machines using externally provided power would be able to continue operating even when the tissue itself was no longer functional. We would finally have an ability to heal injured cells, instead of simply helping injured cells to heal themselves.
9. Nanotechnology and Medical Research
Advances in medical technology necessarily depend on our understanding of living systems. With the kind of devices discussed earlier, we should be able to explore and analyze living systems in greater detail than ever before considered possible.
Autonomous molecular machines, operating in the human body, could monitor levels of different compounds and store that information in internal memory. They could determine both their location and the time. Thus, information could be gathered about changing conditions inside the body, and that information could be tied to both the location and the time of collection. Physical samples of small volumes (nano tissue samples) could likewise be taken.
These molecular machines could then be filtered out of the blood supply and the stored information (and samples) could be analyzed. This would provide a picture of activities within healthy or injured tissue. This new knowledge would give us new insights and new approaches to curing the sick and healing the injured.
10. Taking snapshots of the entire system
More dramatically, it should be feasible to take "snapshots" of tissue samples and analyze the structure down to the molecular level. First, a small tissue sample could be either fixed or frozen. Chemical fixation can be used to rapidly block most tissue changes. Ultra fast freezing of small tissue samples is an effective method of halting essentially all chemical processes and diffusion of all molecules.
Once fixed or frozen, the tissue sample could be analyzed in a leisurely fashion. With nanotechnology (and indeed, to some extent with current STM and AFM technologies, though rather more expensively) it should be feasible to scan the tissue surface in molecular detail, and store that information in a computer. Once the surface had been scanned, it could be removed in a very selective and precise fashion, and scanned again. As an example, the use of a positionally controlled carbene has been proposed for use in the synthesis of complex diamondoid structures [REF06, REF21]. Such a positionally controlled carbene is highly reactive and, if positioned at an appropriate site on the surface of the tissue being analyzed, would readily react with a surface molecule. This surface molecule could then be removed. A wide variety of other "sticky" molecular tools could be brought up to the surface and allowed to react with surface molecules, which could then be removed, exposing the layers beneath.
The use of a positionally controlled carbene implies that the environment in which it is used must be inert. This requirement could be satisfied by analyzing the tissue sample at very low temperature (a few Kelvins) and in a very good vacuum. Under these conditions the tissue specimen would remain stable during even a protracted analysis process.
While this process can readily be envisioned for very small structures, nanotechnology should make massive parallelism feasible. That is, a single positional device could be used at a certain speed to provide information about a certain (rather small) volume of tissue in a reasonable time. Nanotechnology should permit the manufacture of a large number of small devices, each able to analyze a small volume. Given enough such devices operating in parallel, larger volumes could be analyzed and the information from many individual devices integrated to provide a coherent picture of the larger whole. Effective use of this option will require massive computational power -- which will also be made feasible with nanotechnology. Estimates of the computational power that should be provided by nanotechnology exceed 10^24 logic operations per second for a single desktop computer[REF06]. This amount of raw computational power should make control of a large number of parallel devices feasible, and should permit integration and analysis of the information so obtained.
In short, tissue samples could be "frozen" (either literally by ultrafast cooling or figuratively by chemical fixation) and the entire resulting tissue sample could be analyzed down to the level of individual molecules. The information so obtained could be processed by computers able to handle the flood of data produced. The resulting "snapshots" will provide us with an instantaneous look at metabolic and cellular activities across even relatively large volumes of tissue. Such an ability should revolutionize our understanding of the complex processes that take place in living systems. The possibility of truly revolutionary advances in our medical abilities has also created renewed interest in cryonics.
11. How Long?
The abilities discussed here might well take years or decades to develop. It is quite natural to ask: "When might we see these systems actually used?" The scientifically correct answer is, of course, "We don't know." That said, it is worth noting that if progress in computer hardware continues as the trend lines of the last 50 years suggest, we should have some form of molecular manufacturing in the 2010 to 2020 time frame. After this, the medical applications will require some additional time to develop.
The remarkably steady trend lines in computer hardware, however, give a false sense that there is a "schedule" and that developments will spontaneously happen at their appointed time. This is incorrect. How long it will take to develop these systems depends very much on what we do. If focused efforts to develop molecular manufacturing and its medical applications are pursued, we will have such systems well within our lifetimes. If we make no special efforts the schedule will slip, possibly by a great deal.
As might be appreciated, developing these systems within our lifetimes would be advantageous for a variety of reasons.
Tuesday, July 12, 2011
Friday, April 29, 2011
Milky way galaxy
Milky Way, the large, disk-shaped aggregation of stars, or galaxy, that includes the Sun and its solar system. In addition to the Sun, the Milky Way contains about 400 billion other stars. There are hundreds of billions of other galaxies in the universe, some of which are much larger and contain many more stars than the Milky Way.
The Milky Way is visible at night, appearing as a faintly luminous band that stretches across the sky. The name Milky Way is derived from Greek mythology, in which the band of light was said to be milk from the breast of the goddess Hera. Its hazy appearance results from the combined light of stars too far away to be distinguished individually by the unaided eye. All of the individual stars that are distinct in the sky lie within the Milky Way Galaxy.
From the middle northern latitudes, the Milky Way is best seen on clear, moonless, summer nights, when it appears as a luminous, irregular band circling the sky from the northeastern to the southeastern horizon. It extends through the constellations Perseus, Cassiopeia, and Cepheus. In the region of the Northern Cross it divides into two streams: the western stream, which is bright as it passes through the Northern Cross, fades near Ophiuchus, or the Serpent Bearer, because of dense dust clouds, and appears again in Scorpio; and the eastern stream, which grows brighter as it passes southward through Scutum and Sagittarius. The brightest part of the Milky Way extends from Scutum to Scorpio, through Sagittarius. The center of the galaxy lies in the direction of Sagittarius and is about 25,000 light-years from the Sun (a light-year is the distance light travels in a year, about 9.46 trillion km or 5.88 trillion mi).
Galaxies have three common shapes: elliptical, spiral, and irregular. Elliptical galaxies have an ovoid or globular shape and generally contain older stars. Spiral galaxies are disk-shaped with arms that curve around their edges, making these galaxies look like whirlpools. Spiral galaxies contain both old and young stars as well as numerous clouds of dust and gas from which new stars are born. Irregular galaxies have no regular structure. Astronomers believe that their structures were distorted by collisions with other galaxies.
Astronomers classify the Milky Way as a large spiral or possibly a barred spiral galaxy, with several spiral arms coiling around a central bulge about 10,000 light-years thick. Stars in the central bulge are close together, while those in the arms are farther apart. The arms also contain clouds of interstellar dust and gas. The disk is about 100,000 light-years in diameter and is surrounded by a larger cloud of hydrogen gas. Surrounding this cloud in turn is a spherical halo that contains many separate globular clusters of stars mainly lying above or below the disk. This halo may be more than twice as wide as the disk itself. In addition, studies of galactic movements suggest that the Milky Way system contains far more matter than is accounted for by the visible disk and attendant clusters—up to 2,000 billion times more mass than the Sun contains.
The Milky Way is the most massive member of a group of about 40 galaxies called the Local Group, which includes another large spiral galaxy known as the Andromeda Galaxy and many dwarf galaxies such as the Magellanic Clouds. Although the Andromeda Galaxy appears to have more stars and visible matter in its disk than the Milky Way does, recent research indicates that the Milky Way has more dark matter and is the more massive of the two. Dark matter is a still unidentified substance that does not give off or reflect detectable electromagnetic radiation but can be measured by its gravitational effects. Dark matter is thought to surround most galaxies as a kind of invisible halo that influences how stars orbit within the galaxy. The mass and density of the dark matter around the Milky Way was determined by studying 12 dwarf galaxies that orbit our galaxy.
The Milky Way is visible at night, appearing as a faintly luminous band that stretches across the sky. The name Milky Way is derived from Greek mythology, in which the band of light was said to be milk from the breast of the goddess Hera. Its hazy appearance results from the combined light of stars too far away to be distinguished individually by the unaided eye. All of the individual stars that are distinct in the sky lie within the Milky Way Galaxy.
From the middle northern latitudes, the Milky Way is best seen on clear, moonless, summer nights, when it appears as a luminous, irregular band circling the sky from the northeastern to the southeastern horizon. It extends through the constellations Perseus, Cassiopeia, and Cepheus. In the region of the Northern Cross it divides into two streams: the western stream, which is bright as it passes through the Northern Cross, fades near Ophiuchus, or the Serpent Bearer, because of dense dust clouds, and appears again in Scorpio; and the eastern stream, which grows brighter as it passes southward through Scutum and Sagittarius. The brightest part of the Milky Way extends from Scutum to Scorpio, through Sagittarius. The center of the galaxy lies in the direction of Sagittarius and is about 25,000 light-years from the Sun (a light-year is the distance light travels in a year, about 9.46 trillion km or 5.88 trillion mi).
Galaxies have three common shapes: elliptical, spiral, and irregular. Elliptical galaxies have an ovoid or globular shape and generally contain older stars. Spiral galaxies are disk-shaped with arms that curve around their edges, making these galaxies look like whirlpools. Spiral galaxies contain both old and young stars as well as numerous clouds of dust and gas from which new stars are born. Irregular galaxies have no regular structure. Astronomers believe that their structures were distorted by collisions with other galaxies.
Astronomers classify the Milky Way as a large spiral or possibly a barred spiral galaxy, with several spiral arms coiling around a central bulge about 10,000 light-years thick. Stars in the central bulge are close together, while those in the arms are farther apart. The arms also contain clouds of interstellar dust and gas. The disk is about 100,000 light-years in diameter and is surrounded by a larger cloud of hydrogen gas. Surrounding this cloud in turn is a spherical halo that contains many separate globular clusters of stars mainly lying above or below the disk. This halo may be more than twice as wide as the disk itself. In addition, studies of galactic movements suggest that the Milky Way system contains far more matter than is accounted for by the visible disk and attendant clusters—up to 2,000 billion times more mass than the Sun contains.
The Milky Way is the most massive member of a group of about 40 galaxies called the Local Group, which includes another large spiral galaxy known as the Andromeda Galaxy and many dwarf galaxies such as the Magellanic Clouds. Although the Andromeda Galaxy appears to have more stars and visible matter in its disk than the Milky Way does, recent research indicates that the Milky Way has more dark matter and is the more massive of the two. Dark matter is a still unidentified substance that does not give off or reflect detectable electromagnetic radiation but can be measured by its gravitational effects. Dark matter is thought to surround most galaxies as a kind of invisible halo that influences how stars orbit within the galaxy. The mass and density of the dark matter around the Milky Way was determined by studying 12 dwarf galaxies that orbit our galaxy.
Computer viruses
A computer virus is a computer program that can copy itself[1] and infect a computer. The term "virus" is also commonly but erroneously used to refer to other types of malware, including but not limited to adware and spyware programs that do not have the reproductive ability. A true virus can spread from one computer to another (in some form of executable code) when its host is taken to the target computer; for instance because a user sent it over a network or the Internet, or carried it on a removable medium such as a floppy disk, CD, DVD, or USB drive.[2]
Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer.[3][4]
As stated above, the term "computer virus" is sometimes used as a catch-all phrase to include all types of malware, even those that do not have the reproductive ability. Malware includes computer viruses, computer worms, Trojan horses, most rootkits, spyware, dishonest adware and other malicious and unwanted software, including true viruses. Viruses are sometimes confused with worms and Trojan horses, which are technically different. A worm can exploit security vulnerabilities to spread itself automatically to other computers through networks, while a Trojan horse is a program that appears harmless but hides malicious functions. Worms and Trojan horses, like viruses, may harm a computer system's data or performance. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious or simply do nothing to call attention to themselves. Some viruses do nothing beyond reproducing themselves.
Virus program
The Creeper virus was first detected on ARPANET, the forerunner of the Internet, in the early 1970s.[10] Creeper was an experimental self-replicating program written by Bob Thomas at BBN Technologies in 1971.[11] Creeper used the ARPANET to infect DEC PDP-10 computers running the TENEX operating system.[12] Creeper gained access via the ARPANET and copied itself to the remote system where the message, "I'm the creeper, catch me if you can!" was displayed. The Reaper program was created to delete Creeper.[13]
A program called "Elk Cloner" was the first computer virus to appear "in the wild" — that is, outside the single computer or lab where it was created.[14] Written in 1981 by Richard Skrenta, it attached itself to the Apple DOS 3.3 operating system and spread via floppy disk.[14][15] This virus, created as a practical joke when Skrenta was still in high school, was injected in a game on a floppy disk. On its 50th use the Elk Cloner virus would be activated, infecting the computer and displaying a short poem beginning "Elk Cloner: The program with a personality."
The first PC virus in the wild was a boot sector virus dubbed (c)Brain,[16] created in 1986 by the Farooq Alvi Brothers in Lahore, Pakistan, reportedly to deter piracy of the software they had written.[17]
Before computer networks became widespread, most viruses spread on removable media, particularly floppy disks. In the early days of the personal computer, many users regularly exchanged information and programs on floppies. Some viruses spread by infecting programs stored on these disks, while others installed themselves into the disk boot sector, ensuring that they would be run when the user booted the computer from the disk, usually inadvertently. PCs of the era would attempt to boot first from a floppy if one had been left in the drive. Until floppy disks fell out of use, this was the most successful infection strategy and boot sector viruses were the most common in the wild for many years.[1]
Traditional computer viruses emerged in the 1980s, driven by the spread of personal computers and the resultant increase in BBS, modem use, and software sharing. Bulletin board-driven software sharing contributed directly to the spread of Trojan horse programs, and viruses were written to infect popularly traded software. Shareware and bootleg software were equally common vectors for viruses on BBS's.[citation needed]
Macro viruses have become common since the mid-1990s. Most of these viruses are written in the scripting languages for Microsoft programs such as Word and Excel and spread throughout Microsoft Office by infecting documents and spreadsheets. Since Word and Excel were also available for Mac OS, most could also spread to Macintosh computers. Although most of these viruses did not have the ability to send infected email messages, those viruses which did take advantage of the Microsoft Outlook COM interface.[citation needed]
Some old versions of Microsoft Word allow macros to replicate themselves with additional blank lines. If two macro viruses simultaneously infect a document, the combination of the two, if also self-replicating, can appear as a "mating" of the two and would likely be detected as a virus unique from the "parents".[18]
A virus may also send a web address link as an instant message to all the contacts on an infected machine. If the recipient, thinking the link is from a friend (a trusted source) follows the link to the website, the virus hosted at the site may be able to infect this new computer and continue propagating.
Viruses that spread using cross-site scripting were first reported in 2002,[19] and were academically demonstrated in 2005.[20] There have been multiple instances of the cross-site scripting viruses in the wild, exploiting websites such as MySpace and Yahoo.
Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer.[3][4]
As stated above, the term "computer virus" is sometimes used as a catch-all phrase to include all types of malware, even those that do not have the reproductive ability. Malware includes computer viruses, computer worms, Trojan horses, most rootkits, spyware, dishonest adware and other malicious and unwanted software, including true viruses. Viruses are sometimes confused with worms and Trojan horses, which are technically different. A worm can exploit security vulnerabilities to spread itself automatically to other computers through networks, while a Trojan horse is a program that appears harmless but hides malicious functions. Worms and Trojan horses, like viruses, may harm a computer system's data or performance. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious or simply do nothing to call attention to themselves. Some viruses do nothing beyond reproducing themselves.
Virus program
The Creeper virus was first detected on ARPANET, the forerunner of the Internet, in the early 1970s.[10] Creeper was an experimental self-replicating program written by Bob Thomas at BBN Technologies in 1971.[11] Creeper used the ARPANET to infect DEC PDP-10 computers running the TENEX operating system.[12] Creeper gained access via the ARPANET and copied itself to the remote system where the message, "I'm the creeper, catch me if you can!" was displayed. The Reaper program was created to delete Creeper.[13]
A program called "Elk Cloner" was the first computer virus to appear "in the wild" — that is, outside the single computer or lab where it was created.[14] Written in 1981 by Richard Skrenta, it attached itself to the Apple DOS 3.3 operating system and spread via floppy disk.[14][15] This virus, created as a practical joke when Skrenta was still in high school, was injected in a game on a floppy disk. On its 50th use the Elk Cloner virus would be activated, infecting the computer and displaying a short poem beginning "Elk Cloner: The program with a personality."
The first PC virus in the wild was a boot sector virus dubbed (c)Brain,[16] created in 1986 by the Farooq Alvi Brothers in Lahore, Pakistan, reportedly to deter piracy of the software they had written.[17]
Before computer networks became widespread, most viruses spread on removable media, particularly floppy disks. In the early days of the personal computer, many users regularly exchanged information and programs on floppies. Some viruses spread by infecting programs stored on these disks, while others installed themselves into the disk boot sector, ensuring that they would be run when the user booted the computer from the disk, usually inadvertently. PCs of the era would attempt to boot first from a floppy if one had been left in the drive. Until floppy disks fell out of use, this was the most successful infection strategy and boot sector viruses were the most common in the wild for many years.[1]
Traditional computer viruses emerged in the 1980s, driven by the spread of personal computers and the resultant increase in BBS, modem use, and software sharing. Bulletin board-driven software sharing contributed directly to the spread of Trojan horse programs, and viruses were written to infect popularly traded software. Shareware and bootleg software were equally common vectors for viruses on BBS's.[citation needed]
Macro viruses have become common since the mid-1990s. Most of these viruses are written in the scripting languages for Microsoft programs such as Word and Excel and spread throughout Microsoft Office by infecting documents and spreadsheets. Since Word and Excel were also available for Mac OS, most could also spread to Macintosh computers. Although most of these viruses did not have the ability to send infected email messages, those viruses which did take advantage of the Microsoft Outlook COM interface.[citation needed]
Some old versions of Microsoft Word allow macros to replicate themselves with additional blank lines. If two macro viruses simultaneously infect a document, the combination of the two, if also self-replicating, can appear as a "mating" of the two and would likely be detected as a virus unique from the "parents".[18]
A virus may also send a web address link as an instant message to all the contacts on an infected machine. If the recipient, thinking the link is from a friend (a trusted source) follows the link to the website, the virus hosted at the site may be able to infect this new computer and continue propagating.
Viruses that spread using cross-site scripting were first reported in 2002,[19] and were academically demonstrated in 2005.[20] There have been multiple instances of the cross-site scripting viruses in the wild, exploiting websites such as MySpace and Yahoo.
Sinhala and Tamil new year
The timing of the Sinhala New Year coincides with the new year celebrations of many traditional calendars of South and Southeast Asia. The festival has close semblance to the Thai New year, Bengali New Year, and Sankranthi festival in India[citation needed].
Cultural anthropological history of the 'Traditional New Year' which is celebrated on month of April, goes back to an ancient period in Sri Lankan history. Various beliefs, perhaps those associated with fertility of the harvest, gave birth to many rituals, customs, and ceremonies connected with the New Year. The advent of Buddhism in the third century BC (300BC) led to a re-interpretation of the existing New Year activities in the Buddhism light[citation needed]. The majority of the people in the country are Buddhists, and as such, it is that the Buddhist outlook was predominant in transforming the New Year rites to what they are now.
Hinduism, on the other hand, existed side by side with Buddhism, in medieval times. New Year practices interpreted in the Hinduism way developed among the Hindus[citation needed]. Buddhism and Hinduism were historically connected with each other. Their philosophies were running along parallel dimensions, except for certain ultimate truths concerning the self, the way to achieve emancipation and the nature of a creative god(which Buddhism denies)and nirvana . There was no serious contradiction in New Year rituals that are found among the Buddhists and Hindus.
The mythological backdrop of the New Year is probably based on Hindu literature. The Prince of Peace called Indradeva descends upon the earth to ensure peace and happiness. He comes in a white carriage wearing on his head a white floral crown seven cubits high. He first dips, like a returning space capsule plunges, breaking earth's gravity, into a `Kiri Sayura' or sea of milk.[citation needed]
Modern day activities related to the celebration of the traditional New Year is based on auspicious times given by the astrologers. The New Year celebration is therefore can be thought as a complex mix of Indigenous, Astrological, Hindu, and Buddhist traditions.
•
[edit] Celebrations
In month of Bak in the Buddhist calendar (or the month of April according to the gregorian calendar), when the sun moves (in an astrological sense) from the Meena Rashiya (House of Pisces) to the Mesha Rashiya (House of Aries) in the celestial sphere; Sri Lankapeople of Sri Lanka begin celebrating Sinhala New Year or Aluth Avurudu (in Sinhala). It marks the end of the harvest season and also coincides with one of two instances when the sun is directly above Sri Lanka.
However, unlike the celebration of the new gregorian calender year at midnight on December 31, the Sinhalese traditional New Year begins at a time determined by astrological calculations. Also unlike 31st night celebrations, where old year ends at midnight and new year begins immediately afterwards; the ending of the old year, and the beginning of the new year occur several hours apart from one another (this span of time is usually 12 hours and 48 minutes, which starts when the sun, as a disk, starts to cross the astrological boundary between 'House of Pisces' and 'House of Aries' and ends when the crossing is complete. The halfway point is considered as the dawn of the new year). This period is, referred to as the Nonagathe (or the 'neutral period'). During this time Sri Lankans are, according to tradition, encouraged to refrain from material pursuits, and engage solely in either religious activities or traditional games.
Cultural rituals begin shortly after the beginning of the Sinhala new year with the cleaning of the house and lighting of an oil lamp. In some communities, women congregate to play upon on the Raban (type of a drum) to announce the incipient change in the year. All the families as one carries out variety of rituals in exact timings of which are determined by astrological calculations - from lighting the fire to making the Kiribath (milk rice) to entering into the first business transaction and eating the first morsels. The rituals vary slightly based on the locale. However the core of the celebrations remains the same.
The approach of the each auspicious time for various rituvals is heralded by the unmistakable sign of very loud firecrackers. Although loud firecrackers are an environmental concern, and a safety hazard, especially for children, this remains an integral part of the celebrations throughout Sri Lanka.
Once the important rituals are done, the partying begins as families mingle in the streets, homes are thrown open and children are let out to play. The ubiquitous plantain is dished out alongside celebratory feasts of Kavum (small oil cake) and Kokis (crisp and light sweetmeat, originally from the Netherlands). However, the extent of outdoor activities depends largely on the neighborhood. The suburban communities tend to have such social gatherings than urban or city dwellers.
Aluth Aurudu is an important national holiday for both the cultures of the Sinhalese people and the Tamil people of Sri Lanka. The celebrations are given wide coverage and patronage from state owned media as well as private media. Although it is being promoted as a national or cultural event, due to the fact that it is based on astrology, the Christians & Muslims that do not follow astrology tend to either totally refrain from celebrations, or do the minimum required to maintain the social connections with Sinhalese people and Tamil people.
[edit] Harvest Festival
The date upon which the Sinhala new year occurred, while determined by astrological calculations, also tends to coincide with one of the paddy harvest seasons. For farming communities, the traditional new year is a festival of harvest as well.
[edit] Cuckoo bird
A type of cuckoo bird, the Asian Koel, has a strong association with the new year celebrations in traditional literature around the festival. The mating season of the bird roughly coincides with the festival season. The mating call of the male is regarded as a heralding sign of the traditional new year. This bird is known as the Koha in Sri Lanka by the Sinhala language. The melodious call Koo-ooo of the male bird is heard through out Sri Lanka during the breeding season of the bird that roughly spans from March to August.
[edit] See also
Cultural anthropological history of the 'Traditional New Year' which is celebrated on month of April, goes back to an ancient period in Sri Lankan history. Various beliefs, perhaps those associated with fertility of the harvest, gave birth to many rituals, customs, and ceremonies connected with the New Year. The advent of Buddhism in the third century BC (300BC) led to a re-interpretation of the existing New Year activities in the Buddhism light[citation needed]. The majority of the people in the country are Buddhists, and as such, it is that the Buddhist outlook was predominant in transforming the New Year rites to what they are now.
Hinduism, on the other hand, existed side by side with Buddhism, in medieval times. New Year practices interpreted in the Hinduism way developed among the Hindus[citation needed]. Buddhism and Hinduism were historically connected with each other. Their philosophies were running along parallel dimensions, except for certain ultimate truths concerning the self, the way to achieve emancipation and the nature of a creative god(which Buddhism denies)and nirvana . There was no serious contradiction in New Year rituals that are found among the Buddhists and Hindus.
The mythological backdrop of the New Year is probably based on Hindu literature. The Prince of Peace called Indradeva descends upon the earth to ensure peace and happiness. He comes in a white carriage wearing on his head a white floral crown seven cubits high. He first dips, like a returning space capsule plunges, breaking earth's gravity, into a `Kiri Sayura' or sea of milk.[citation needed]
Modern day activities related to the celebration of the traditional New Year is based on auspicious times given by the astrologers. The New Year celebration is therefore can be thought as a complex mix of Indigenous, Astrological, Hindu, and Buddhist traditions.
•
[edit] Celebrations
In month of Bak in the Buddhist calendar (or the month of April according to the gregorian calendar), when the sun moves (in an astrological sense) from the Meena Rashiya (House of Pisces) to the Mesha Rashiya (House of Aries) in the celestial sphere; Sri Lankapeople of Sri Lanka begin celebrating Sinhala New Year or Aluth Avurudu (in Sinhala). It marks the end of the harvest season and also coincides with one of two instances when the sun is directly above Sri Lanka.
However, unlike the celebration of the new gregorian calender year at midnight on December 31, the Sinhalese traditional New Year begins at a time determined by astrological calculations. Also unlike 31st night celebrations, where old year ends at midnight and new year begins immediately afterwards; the ending of the old year, and the beginning of the new year occur several hours apart from one another (this span of time is usually 12 hours and 48 minutes, which starts when the sun, as a disk, starts to cross the astrological boundary between 'House of Pisces' and 'House of Aries' and ends when the crossing is complete. The halfway point is considered as the dawn of the new year). This period is, referred to as the Nonagathe (or the 'neutral period'). During this time Sri Lankans are, according to tradition, encouraged to refrain from material pursuits, and engage solely in either religious activities or traditional games.
Cultural rituals begin shortly after the beginning of the Sinhala new year with the cleaning of the house and lighting of an oil lamp. In some communities, women congregate to play upon on the Raban (type of a drum) to announce the incipient change in the year. All the families as one carries out variety of rituals in exact timings of which are determined by astrological calculations - from lighting the fire to making the Kiribath (milk rice) to entering into the first business transaction and eating the first morsels. The rituals vary slightly based on the locale. However the core of the celebrations remains the same.
The approach of the each auspicious time for various rituvals is heralded by the unmistakable sign of very loud firecrackers. Although loud firecrackers are an environmental concern, and a safety hazard, especially for children, this remains an integral part of the celebrations throughout Sri Lanka.
Once the important rituals are done, the partying begins as families mingle in the streets, homes are thrown open and children are let out to play. The ubiquitous plantain is dished out alongside celebratory feasts of Kavum (small oil cake) and Kokis (crisp and light sweetmeat, originally from the Netherlands). However, the extent of outdoor activities depends largely on the neighborhood. The suburban communities tend to have such social gatherings than urban or city dwellers.
Aluth Aurudu is an important national holiday for both the cultures of the Sinhalese people and the Tamil people of Sri Lanka. The celebrations are given wide coverage and patronage from state owned media as well as private media. Although it is being promoted as a national or cultural event, due to the fact that it is based on astrology, the Christians & Muslims that do not follow astrology tend to either totally refrain from celebrations, or do the minimum required to maintain the social connections with Sinhalese people and Tamil people.
[edit] Harvest Festival
The date upon which the Sinhala new year occurred, while determined by astrological calculations, also tends to coincide with one of the paddy harvest seasons. For farming communities, the traditional new year is a festival of harvest as well.
[edit] Cuckoo bird
A type of cuckoo bird, the Asian Koel, has a strong association with the new year celebrations in traditional literature around the festival. The mating season of the bird roughly coincides with the festival season. The mating call of the male is regarded as a heralding sign of the traditional new year. This bird is known as the Koha in Sri Lanka by the Sinhala language. The melodious call Koo-ooo of the male bird is heard through out Sri Lanka during the breeding season of the bird that roughly spans from March to August.
[edit] See also
Water pollution
Water Pollution, contamination of streams, lakes, underground water, bays, or oceans by substances harmful to living things. Water is necessary to life on earth. All organisms contain it; some live in it; some drink it. Plants and animals require water that is moderately pure, and they cannot survive if their water is loaded with toxic chemicals or harmful microorganisms. If severe, water pollution can kill large numbers of fish, birds, and other animals, in some cases killing all members of a species in an affected area. Pollution makes streams, lakes, and coastal waters unpleasant to look at, to smell, and to swim in. Fish and shellfish harvested from polluted waters may be unsafe to eat. People who ingest polluted water can become ill, and, with prolonged exposure, may develop cancers or bear children with birth defects.
The major water pollutants are chemical, biological, or physical materials that degrade water quality. Pollutants can be classed into eight categories, each of which presents its own set of hazards.
Oil and chemicals derived from oil are used for fuel, lubrication, plastics manufacturing, and many other purposes. These petroleum products get into water mainly by means of accidental spills from ships, tanker trucks, pipelines, and leaky underground storage tanks. Many petroleum products are poisonous if ingested by animals, and spilled oil damages the feathers of birds or the fur of animals, often causing death. In addition, spilled oil may be contaminated with other harmful substances, such as polychlorinated biphenyls (PCBs).
Chemicals used to kill unwanted animals and plants, for instance on farms or in suburban yards, may be collected by rainwater runoff and carried into streams, especially if these substances are applied too lavishly. Some of these chemicals are biodegradable and quickly decay into harmless or less harmful forms, while others are nonbiodegradable and remain dangerous for a long time.
When animals consume plants that have been treated with certain nonbiodegradable chemicals, such as chlordane and dichlorodiphenyltrichloroethane (DDT), these chemicals are absorbed into the tissues or organs of the animals. When other animals feed on these contaminated animals, the chemicals are passed up the food chain. With each step up the food chain, the concentration of the pollutant increases. This process is called biomagnification. In one study, DDT levels in ospreys (a family of fish-eating birds) were found to be 10 to 50 times higher than in the fish that they ate, 600 times the level in the plankton that the fish ate, and 10 million times higher than in the water. Animals at the top of food chains may, as a result of these chemical concentrations, suffer cancers, reproductive problems, and death.
Many drinking water supplies are contaminated with pesticides from widespread agricultural use. More than 14 million Americans drink water contaminated with pesticides, and the Environmental Protection Agency (EPA) estimates that 10 percent of wells contain pesticides. Nitrates, a pollutant often derived from fertilizer runoff, can cause methemoglobinemia in infants, a potentially lethal form of anemia that is also called blue baby syndrome.
Heavy metals, such as copper, lead, mercury, and selenium, get into water from many sources, including industries, automobile exhaust, mines, and even natural soil. Like pesticides, heavy metals become more concentrated as animals feed on plants and are consumed in turn by other animals. When they reach high levels in the body, heavy metals can be immediately poisonous, or can result in long-term health problems similar to those caused by pesticides and herbicides. For example, cadmium in fertilizer derived from sewage sludge can be absorbed by crops. If these crops are eaten by humans in sufficient amounts, the metal can cause diarrhea and, over time, liver and kidney damage. Lead can get into water from lead pipes and solder in older water systems; children exposed to lead in water can suffer mental retardation.
D. Hazardous Wastes
Hazardous wastes are chemical wastes that are either toxic (poisonous), reactive (capable of producing explosive or toxic gases), corrosive (capable of corroding steel), or ignitable (flammable). If improperly treated or stored, hazardous wastes can pollute water supplies. In 1969 the Cuyahoga River in Cleveland, Ohio, was so polluted with hazardous wastes that it caught fire and burned. PCBs, a class of chemicals once widely used in electrical equipment such as transformers, can get into the environment through oil spills and can reach toxic levels as organisms eat one another.
E. Excess Organic Matter
Fertilizers and other nutrients used to promote plant growth on farms and in gardens may find their way into water. At first, these nutrients encourage the growth of plants and algae in water. However, when the plant matter and algae die and settle underwater, microorganisms decompose them. In the process of decomposition, these microorganisms consume oxygen that is dissolved in the water. Oxygen levels in the water may drop to such dangerously low levels that oxygen-dependent animals in the water, such as fish, die. This process of depleting oxygen to deadly levels is called eutrophication.
F. Sediment
Sediment, soil particles carried to a streambed, lake, or ocean, can also be a pollutant if it is present in large enough amounts. Soil erosion produced by the removal of soil-trapping trees near waterways, or carried by rainwater and floodwater from croplands, strip mines, and roads, can damage a stream or lake by introducing too much nutrient matter. This leads to eutrophication. Sedimentation can also cover streambed gravel in which many fish, such as salmon and trout, lay their eggs.
A 1994 study by the Centers for Disease Control and Prevention (CDC) estimated that about 900,000 people get sick annually in the United States because of organisms in their drinking water, and around 900 people die. Many disease-causing organisms that are present in small numbers in most natural waters are considered pollutants when found in drinking water. Such parasites as Giardia lamblia and Cryptosporidium parvum occasionally turn up in urban water supplies. These parasites can cause illness, especially in people who are very old or very young, and in people who are already suffering from other diseases. In 1993 an outbreak of Cryptosporidium in the water supply of Milwaukee, Wisconsin, sickened more than 400,000 people and killed more than 100.
H. Thermal Pollution
Water is often drawn from rivers, lakes, or the ocean for use as a coolant in factories and power plants. The water is usually returned to the source warmer than when it was taken. Even small temperature changes in a body of water can drive away the fish and other species that were originally present, and attract other species in place of them. Thermal pollution can accelerate biological processes in plants and animals or deplete oxygen levels in water. The result may be fish and other wildlife deaths near the discharge source. Thermal pollution can also be caused by the removal of trees and vegetation that shade and cool streams.
Sources of water poluttant
Water pollutants result from many human activities. Pollutants from industrial sources may pour out from the outfall pipes of factories or may leak from pipelines and underground storage tanks. Polluted water may flow from mines where the water has leached through mineral-rich rocks or has been contaminated by the chemicals used in processing the ores. Cities and other residential communities contribute mostly sewage, with traces of household chemicals mixed in. Sometimes industries discharge pollutants into city sewers, increasing the variety of pollutants in municipal areas. Pollutants from such agricultural sources as farms, pastures, feedlots, and ranches contribute animal wastes, agricultural chemicals, and sediment from erosion.
The oceans, vast as they are, are not invulnerable to pollution. Pollutants reach the sea from adjacent shorelines, from ships, and from offshore oil platforms. Sewage and food waste discarded from ships on the open sea do little harm, but plastics thrown overboard can kill birds or marine animals by entangling them, choking them, or blocking their digestive tracts if swallowed.
Oil spills often occur through accidents, such as the wrecks of the tanker Amoco Cadiz off the French coast in 1978 and the Exxon Valdez in Alaska in 1992. Routine and deliberate discharges, when tanks are flushed out with seawater, also add a lot of oil to the oceans. Offshore oil platforms also produce spills: The second largest oil spill on record was in the Gulf of Mexico in 1979 when the Ixtoc 1 well spilled 530 million liters (140 million gallons). The largest oil spill ever was the result of an act of war. During the Gulf War of 1991, Iraqi forces destroyed eight tankers and onshore terminals in Kuwait, releasing a record 910 million liters (240 million gallons). An oil spill has its worst effects when the oil slick encounters a shoreline. Oil in coastal waters kills tidepool life and harms birds and marine mammals by causing feathers and fur to lose their natural waterproof quality, which causes the animals to drown or die of cold. Additionally, these animals can become sick or poisoned when they swallow the oil while preening (grooming their feathers or fur).
Water pollution can also be caused by other types of pollution. For example, sulfur dioxide from a power plant’s chimney begins as air pollution. The polluted air mixes with atmospheric moisture to produce airborne sulfuric acid, which falls to the earth as acid rain. In turn, the acid rain can be carried into a stream or lake, becoming a form of water pollution that can harm or even eliminate wildlife. Similarly, the garbage in a landfill can create water pollution if rainwater percolating through the garbage absorbs toxins before it sinks into the soil and contaminates the underlying groundwater (water that is naturally stored underground in beds of gravel and sand, called aquifers).
Pollution may reach natural waters at spots we can easily identify, known as point sources, such as waste pipes or mine shafts. Nonpoint sources are more difficult to recognize. Pollutants from these sources may appear a little at a time from large areas, carried along by rainfall or snowmelt. For instance, the small oil leaks from automobiles that produce discolored spots on the asphalt of parking lots become nonpoint sources of water pollution when rain carries the oil into local waters. Most agricultural pollution is nonpoint since it typically originates from many fields.
The major water pollutants are chemical, biological, or physical materials that degrade water quality. Pollutants can be classed into eight categories, each of which presents its own set of hazards.
Oil and chemicals derived from oil are used for fuel, lubrication, plastics manufacturing, and many other purposes. These petroleum products get into water mainly by means of accidental spills from ships, tanker trucks, pipelines, and leaky underground storage tanks. Many petroleum products are poisonous if ingested by animals, and spilled oil damages the feathers of birds or the fur of animals, often causing death. In addition, spilled oil may be contaminated with other harmful substances, such as polychlorinated biphenyls (PCBs).
Chemicals used to kill unwanted animals and plants, for instance on farms or in suburban yards, may be collected by rainwater runoff and carried into streams, especially if these substances are applied too lavishly. Some of these chemicals are biodegradable and quickly decay into harmless or less harmful forms, while others are nonbiodegradable and remain dangerous for a long time.
When animals consume plants that have been treated with certain nonbiodegradable chemicals, such as chlordane and dichlorodiphenyltrichloroethane (DDT), these chemicals are absorbed into the tissues or organs of the animals. When other animals feed on these contaminated animals, the chemicals are passed up the food chain. With each step up the food chain, the concentration of the pollutant increases. This process is called biomagnification. In one study, DDT levels in ospreys (a family of fish-eating birds) were found to be 10 to 50 times higher than in the fish that they ate, 600 times the level in the plankton that the fish ate, and 10 million times higher than in the water. Animals at the top of food chains may, as a result of these chemical concentrations, suffer cancers, reproductive problems, and death.
Many drinking water supplies are contaminated with pesticides from widespread agricultural use. More than 14 million Americans drink water contaminated with pesticides, and the Environmental Protection Agency (EPA) estimates that 10 percent of wells contain pesticides. Nitrates, a pollutant often derived from fertilizer runoff, can cause methemoglobinemia in infants, a potentially lethal form of anemia that is also called blue baby syndrome.
Heavy metals, such as copper, lead, mercury, and selenium, get into water from many sources, including industries, automobile exhaust, mines, and even natural soil. Like pesticides, heavy metals become more concentrated as animals feed on plants and are consumed in turn by other animals. When they reach high levels in the body, heavy metals can be immediately poisonous, or can result in long-term health problems similar to those caused by pesticides and herbicides. For example, cadmium in fertilizer derived from sewage sludge can be absorbed by crops. If these crops are eaten by humans in sufficient amounts, the metal can cause diarrhea and, over time, liver and kidney damage. Lead can get into water from lead pipes and solder in older water systems; children exposed to lead in water can suffer mental retardation.
D. Hazardous Wastes
Hazardous wastes are chemical wastes that are either toxic (poisonous), reactive (capable of producing explosive or toxic gases), corrosive (capable of corroding steel), or ignitable (flammable). If improperly treated or stored, hazardous wastes can pollute water supplies. In 1969 the Cuyahoga River in Cleveland, Ohio, was so polluted with hazardous wastes that it caught fire and burned. PCBs, a class of chemicals once widely used in electrical equipment such as transformers, can get into the environment through oil spills and can reach toxic levels as organisms eat one another.
E. Excess Organic Matter
Fertilizers and other nutrients used to promote plant growth on farms and in gardens may find their way into water. At first, these nutrients encourage the growth of plants and algae in water. However, when the plant matter and algae die and settle underwater, microorganisms decompose them. In the process of decomposition, these microorganisms consume oxygen that is dissolved in the water. Oxygen levels in the water may drop to such dangerously low levels that oxygen-dependent animals in the water, such as fish, die. This process of depleting oxygen to deadly levels is called eutrophication.
F. Sediment
Sediment, soil particles carried to a streambed, lake, or ocean, can also be a pollutant if it is present in large enough amounts. Soil erosion produced by the removal of soil-trapping trees near waterways, or carried by rainwater and floodwater from croplands, strip mines, and roads, can damage a stream or lake by introducing too much nutrient matter. This leads to eutrophication. Sedimentation can also cover streambed gravel in which many fish, such as salmon and trout, lay their eggs.
A 1994 study by the Centers for Disease Control and Prevention (CDC) estimated that about 900,000 people get sick annually in the United States because of organisms in their drinking water, and around 900 people die. Many disease-causing organisms that are present in small numbers in most natural waters are considered pollutants when found in drinking water. Such parasites as Giardia lamblia and Cryptosporidium parvum occasionally turn up in urban water supplies. These parasites can cause illness, especially in people who are very old or very young, and in people who are already suffering from other diseases. In 1993 an outbreak of Cryptosporidium in the water supply of Milwaukee, Wisconsin, sickened more than 400,000 people and killed more than 100.
H. Thermal Pollution
Water is often drawn from rivers, lakes, or the ocean for use as a coolant in factories and power plants. The water is usually returned to the source warmer than when it was taken. Even small temperature changes in a body of water can drive away the fish and other species that were originally present, and attract other species in place of them. Thermal pollution can accelerate biological processes in plants and animals or deplete oxygen levels in water. The result may be fish and other wildlife deaths near the discharge source. Thermal pollution can also be caused by the removal of trees and vegetation that shade and cool streams.
Sources of water poluttant
Water pollutants result from many human activities. Pollutants from industrial sources may pour out from the outfall pipes of factories or may leak from pipelines and underground storage tanks. Polluted water may flow from mines where the water has leached through mineral-rich rocks or has been contaminated by the chemicals used in processing the ores. Cities and other residential communities contribute mostly sewage, with traces of household chemicals mixed in. Sometimes industries discharge pollutants into city sewers, increasing the variety of pollutants in municipal areas. Pollutants from such agricultural sources as farms, pastures, feedlots, and ranches contribute animal wastes, agricultural chemicals, and sediment from erosion.
The oceans, vast as they are, are not invulnerable to pollution. Pollutants reach the sea from adjacent shorelines, from ships, and from offshore oil platforms. Sewage and food waste discarded from ships on the open sea do little harm, but plastics thrown overboard can kill birds or marine animals by entangling them, choking them, or blocking their digestive tracts if swallowed.
Oil spills often occur through accidents, such as the wrecks of the tanker Amoco Cadiz off the French coast in 1978 and the Exxon Valdez in Alaska in 1992. Routine and deliberate discharges, when tanks are flushed out with seawater, also add a lot of oil to the oceans. Offshore oil platforms also produce spills: The second largest oil spill on record was in the Gulf of Mexico in 1979 when the Ixtoc 1 well spilled 530 million liters (140 million gallons). The largest oil spill ever was the result of an act of war. During the Gulf War of 1991, Iraqi forces destroyed eight tankers and onshore terminals in Kuwait, releasing a record 910 million liters (240 million gallons). An oil spill has its worst effects when the oil slick encounters a shoreline. Oil in coastal waters kills tidepool life and harms birds and marine mammals by causing feathers and fur to lose their natural waterproof quality, which causes the animals to drown or die of cold. Additionally, these animals can become sick or poisoned when they swallow the oil while preening (grooming their feathers or fur).
Water pollution can also be caused by other types of pollution. For example, sulfur dioxide from a power plant’s chimney begins as air pollution. The polluted air mixes with atmospheric moisture to produce airborne sulfuric acid, which falls to the earth as acid rain. In turn, the acid rain can be carried into a stream or lake, becoming a form of water pollution that can harm or even eliminate wildlife. Similarly, the garbage in a landfill can create water pollution if rainwater percolating through the garbage absorbs toxins before it sinks into the soil and contaminates the underlying groundwater (water that is naturally stored underground in beds of gravel and sand, called aquifers).
Pollution may reach natural waters at spots we can easily identify, known as point sources, such as waste pipes or mine shafts. Nonpoint sources are more difficult to recognize. Pollutants from these sources may appear a little at a time from large areas, carried along by rainfall or snowmelt. For instance, the small oil leaks from automobiles that produce discolored spots on the asphalt of parking lots become nonpoint sources of water pollution when rain carries the oil into local waters. Most agricultural pollution is nonpoint since it typically originates from many fields.
Srilanka
Sri Lanka is a republic and a unitary state which is governed by a semi-presidential system with its official seat of government in Sri Jayawardenapura-Kotte, the capital.
As a result of its location in the path of major sea routes, Sri Lanka is a strategic naval link between West Asia and South East Asia.[12] It has also been a center of the Buddhist religion and culture from ancient times and is one of the few remaining abodes of Buddhism in South Asia along with Ladakh, Bhutan and the Chittagong hill tracts[13] The Sinhalese community forms the majority of the population; Tamils, who are concentrated in the north and east of the island, form the largest ethnic minority. Other communities include Moors, Burghers, Kaffirs, Malays and the aboriginal Vedda people.
The country is famous for the production and export of tea, coffee, coconuts, rubber and cinnamon, the latter which is native to the country.[14] The natural beauty Sri Lanka has led to the title The Pearl of the Indian Ocean, it is full of lush tropical forests, white beaches and diverse landscape throughout along with a rich biodiversity. The country lays claim to a long and colorful history of over three thousand years, having one of the longest documented histories in the world. Sri Lanka's rich culture can be attributed to the many different communities in the island. Sri Lanka is a founding member state of SAARC and a member United Nations, Commonwealth of Nations, G77 and Non-Aligned Movement.
•
The island of Sri Lanka lies in the Indian Ocean, to the southwest of the Bay of Bengal. It is separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait. According to Hindu mythology, a land bridge to the Indian mainland, known as Rama's Bridge, was constructed during the time of Rama by the vanara architect Nala. Often referred to as Adam's Bridge, it now amounts to only a chain of limestone shoals remaining above sea level.[21]
According to colonial British reports, this is a natural causeway which was formerly complete, but was breached by a violent storm in 1480.[22] The island consists mostly of flat-to-rolling coastal plains, with mountains rising only in the south-central part. Amongst these is the highest point Pidurutalagala, reaching 2,524 metres (8,281 ft) above sea level.
The climate of Sri Lanka can be described as tropical and warm. Its position between 5 and 10 north latitude endows the country with a warm climate moderated by ocean winds and considerable moisture. The mean temperature ranges from about 16 °C (60.8 °F) in the Central Highlands, where frost may occur for several days in the winter, to a maximum of approximately 33 °C (91.4 °F) in other low-altitude areas. The average yearly temperature ranges from 28 °C (82.4 °F) to nearly 31 °C (87.8 °F). Day and night temperatures may vary by 4 °C (7.20 °F) to 7 °C (12.60 °F). During the coldest days of January, many people wear coats and sweaters in the highlands and elsewhere.
May, the hottest period, precedes the summer monsoon rains. The rainfall pattern is influenced by monsoon winds from the Indian Ocean and Bay of Bengal: as the winds encounter the mountain slopes of the Central Highlands, they unload heavy rains on the slopes and the southwestern areas of the island. Some of the windward slopes receive up to 2,500 millimetres (98.4 in) of rain each month, but the leeward slopes in the east and northeast receive little rain. Periodic squalls occur and sometimes tropical cyclones bring overcast skies and rains to the southwest, northeast, and eastern parts of the island.
Between December and March, monsoon winds come from the northeast, bringing moisture from the Bay of Bengal. Humidity is typically higher in the southwest and mountainous areas and depends on the seasonal patterns of rainfall, and places like Colombo experience daytime humidity above 70% all year round, rising to almost 90% during the monsoon season in June. Anuradhapura experiences a daytime low of 60% during the monsoon month of March, but a high of 79% during the November and December rains. In the highlands, Kandy's daytime humidity usually ranges between 70% and 79%.
The mountains and the southwestern part of the country, known as the "wet zone", receive ample rainfall at an average of 2,500 mm (98 in). Most of the east, southeast, and northern parts of the
country comprise the "dry zone", which receives between 1,200 mm (47 in) and 1,900 mm (75 in) of rain annually. Much of the rain in these areas falls from October to January; during the rest of the year there is very little precipitation. The arid northwest and southeast coasts receive the least amount of rain at 600 mm (24 in) to 1,200 mm (47 in) per year.
Varieties of flowering acacias are well adapted to the arid conditions and flourish on the Jaffna Peninsula. Among the trees of the dry-land forests, are some valuable species such as satinwood, ebony, ironwood, mahogany and teak. In the wet zone, the dominant vegetation of the lowlands is a tropical evergreen forest, with tall trees, broad foliage, and a dense undergrowth of vines and creepers. Subtropical evergreen forests resembling those of temperate climates flourish in the higher altitudes. Forests at one time covered nearly the entire island, but by the late 20th century lands classified as forests and forest reserves covered around ⅓ of the land.[23]
The Yala National Park in the southeast protects herds of elephant, deer, and peacocks, and the Wilpattu National Park in the northwest preserves the habitats of many water birds, such as storks, pelicans, ibis, and spoonbills. During the Mahaweli Ganga Program of the 1970s and
1980s in northern Sri Lanka, the government set aside four areas of land totalling 1,900 km2 (730 sq mi) as national parks. The island has four biosphere reserves, Bundala, Hurulu Forest Reserve, the Kanneliya-Dediyagala-Nakiyadeniya, and Sinharaja.[24]
The national flower of Sri Lanka is the Nymphaea stellata (Sinhalese Nil Mahanel),[25] the national tree is the Ironwood (Sinhalese Na),[26] and the national bird is the Sri Lanka Junglefowl, which is endemic to the country.[27]
Paleolithic human settlements have been discovered at excavations in several cave sites in the Western Plains region and the South-western face of the Central Hills region. Anthropologists believe that some discovered burial rites and certain decorative artefacts exhibit similarities between the first inhabitants of the island and the early inhabitants of Southern India. Recent bioanthropological studies have however dismissed these links, and have placed the origin of the people to the northern parts of India[citation needed].
One of the first written references to the island is found in the Indian epic Ramayana, which described the emperor Ravana as monarch of the powerful kingdom of Lanka, which was created by the divine sculptor Vishwakarma for Kubera, the treasurer of the Gods.[28] English historian James Emerson Tennent also theorised Galle, a southern city in Sri Lanka, was the ancient seaport of Tarshish from which King Solomon is said to have drawn ivory, peacocks and other valuables. The main written accounts of the country's history are the Buddhist chronicles of Mahavansa and Dipavamsa.
The earliest-known inhabitants of the island now known as Sri Lanka were probably the ancestors of the Wanniyala-Aetto people, also known as Veddahs and numbering roughly 3,000. Linguistic analysis has found a correlation of the Sinhalese language with the languages of the Sindh and Gujarat, although most historians believe that the Sinhala community emerged well after the assimilation of various ethnic groups.
From the ancient period date some remarkable archaeological sites including the ruins of Sigiriya, the so-called "Fortress in the Sky", and huge public works. Among the latter are large "tanks" or reservoirs, important for conserving water in a climate that alternates rainy seasons with dry times, and elaborate aqueducts, some with a slope as finely calibrated as one inch to the mile. Ancient Sri Lanka was also the first in the world to have established a dedicated hospital in Mihintale in the 4th century BCE. Ancient Sri Lanka was also the world's leading exporter of cinnamon, which was exported to Egypt as early as 1400 BCE. Sri Lanka was also the first Asian nation to have a female ruler in Queen Anula (47–42 BC).
Ancient Sri Lanka
Since ancient times Sri Lanka was ruled by monarchs, most notably of the Sinha royal dynasty that lasted over 2000 years. The island was also infrequently invaded by South Indian kingdoms and parts of the island were ruled intermittently by the Chola dynasty, the Pandya dynasty, the Chera dynasty and the Pallava dynasty. The island was also invaded by the kingdoms of Kalinga (modern Orissa) and those from the Malay Peninsula.
Buddhism arrived from India in the 3rd century BCE, brought by Bhikkhu Mahinda, who is believed to have been the son of Mauryan emperor Ashoka. Mahinda's mission won over the Sinhalese monarch Devanampiyatissa of Mihintale, who embraced the faith and propagated it throughout the Sinhalese population. The Buddhist kingdoms of Sri Lanka would maintain a large number of Buddhist schools and monasteries, and support the propagation of Buddhism into Southeast Asia.
Sri Lanka had always been an important port and trading post in the ancient world, and was increasingly frequented by merchant ships from the Middle East, Persia, Burma, Thailand, Malaysia, Indonesia and other parts of Southeast Asia. The islands were known to the first European explorers of South Asia and settled by many groups of Arab and Malay merchants.
A Portuguese colonial mission arrived on the island in 1505 headed by Lourenço de Almeida, the son of Francisco de Almeida. At that point the island consisted of three kingdoms, namely Kandy in the central hills, Kotte at the Western coast, and Yarlpanam (Anglicised Jaffna) in the north. The Dutch arrived in the 17th century. Although much of the coastal regions of the island came under the domain of European powers, the interior, hilly region of the island remained independent, with its capital in Kandy.
The British East India Company took over the coastal regions island controlled by the Dutch in 1796, in 1802 these provinces were declaring a crown colony under direct rule of the British government, therefore the island was not part of the British Raj. The annexation of the Kingdom of Kandy in 1815 by the Kandyan convention, unified the island under British rule.
20th Century and the World Wars
European colonists established a series of cinnamon, sugar, coffee, indigo cultivation followed by tea and rubber plantations and graphite mining. The British also brought a large number of indentured workers from Tamil Nadu to work in the plantation economy. The city of Colombo was developed as the administrative centre and commercial heart with its harbor, and the British established modern schools, colleges, roads and churches that brought Western-style education and culture to the native people.
Increasing grievances over the denial of civil rights, mistreatment and abuse of natives by colonial authorities gave rise to a struggle for independence in the 1930s, when the youth leagues opposed the "Ministers' Memorandum," which asked the colonial authority to increase the powers of the board of ministers without granting popular representation or civil freedoms. Buddhist scholars[citation needed] and the Teetotalist Movement also played a vital role in this time.
During World War II, the island served as an important Allied military base. A large segment of the British and American fleet were deployed on the island, as were tens of thousands of soldiers committed to the war against Japan in Southeast Asia. Majority of Ceylonese forget the war as part of British Commonwealth Forces, and some Ceylonese expatriates in the Far east joined to form a Lanka Regiment in the Indian National Army. There was a plan to transport them to Ceylon by submarine, to lead a liberation struggle there[citation needed], but this was aborted.
Independence
The formal ceremony marking the start of self rule, with the opening of the first parliament at Independence Square.
Following the war, popular pressure for independence intensified. The office of Prime Minister of Ceylon was created in advance of independence on 14 October 1947, Don Stephen Senanayake being the first prime minister. On 4 February 1948 the country gained its independence as the Dominion of Ceylon. The island enjoyed good relations with the United Kingdom and had the British Royal Navy stationed at Trincomalee until 1956. With Solomon Bandaranaike elected as prime minister, Ceylon began moving towards links with the communist bloc.
On 21 July 1960 Sirimavo Bandaranaike took office as prime minister, and became the world's first female prime minister[29] and the first female head of government in post-colonial Asia. During her second term as prime minister, her government instituted socialist economic polices and strengthened ties with the USSR and later China, while promoting a policy of non-alignment. However in 1971, Ceylon experienced a Marxist insurrection, which was quickly suppressed with international support. In 1972, with the adaptation of a new constitution, the country became a republic changing its name to Sri Lanka and remained a member of the Commonwealth of Nations.
Civil war
One of the aspects of the independence movement was that it was very much a Sinhalese movement[citation needed]. As a result, the Sinhalese majority attempted to remodel Sri Lanka as a Sinhalese nation-state[citation needed]. The lion in the national flag is derived from the banner of the last Sinhalese Kingdom, which, to the Sinhalese majority, is a symbol of their fight against British colonialism. One single strip of orange on the left part of the flag represents the Tamil population, and it is seen by many Tamil as a symbol of their marginalisation.[citation needed][30]
In 1956, the Official Language Act (commonly referred to as The Sinhala Only Act) was enacted. The law mandated Sinhala, the language of Sri Lanka's majority Sinhalese community, which is spoken by over 70% of Sri Lanka's population, as the sole official language of Sri Lanka. Supporters of the law saw it as an attempt by a community that had just gained independence to distance themselves from their colonial masters.
The immediate (and intended)[citation needed] consequence of this act was to force large numbers of Tamil who worked in the civil service, and who could not meet this language requirement, to resign. An attempt to make Buddhism the national religion, to the exclusion of Hindu and Islam, was also made.[citation needed] Affirmative action in favour of Sinhalese was also instituted, ostensibly to reverse colonial discrimination against Sinhalese in favour of Tamil. Many Tamil[who?], in response to this deliberate marginalisation, came to believe that they deserved a separate nation-state for themselves.[citation needed]
From 1983 to 2009, there was an on-and-off civil war against the government by the Liberation Tigers of Tamil Eelam (LTTE), a separatist militant organisation who fought to create an independent state named Tamil Eelam in the North and East of the island. Both the Sri Lankan government and LTTE have been accused of various human rights violations.[citation needed]
On 19 May 2009, the President of Sri Lanka officially claimed an end to the insurgency and the defeat of the LTTE, following the death of Velupillai Prabhakaran and much of the LTTE's other senior leadership.[31]
Post War
With the end of the war, the government of Sri Lanka called for redevelopment of the nation. The final stages of the war left some 300,000 people displaced.[32] By 2 May 2010, 214,227 IDPs (74%) had been released or returned to their places of origin.[33]
Government and politics
The Supreme Court of Sri Lanka, Colombo.
The Constitution of Sri Lanka establishes a democratic, socialist republic in Sri Lanka, which is also a unitary state. The government is a mixture of the presidential system and the parliamentary system. The President of Sri Lanka is the head of state, the commander in chief of the armed forces, as well as head of government, and is popularly elected for a six-year term.
In the exercise of duties, the President is responsible to the Parliament of Sri Lanka, which is a unicameral 225-member legislature[citation needed]. The President appoints and heads a cabinet of ministers composed of elected members of parliament. The President's deputy is the Prime Minister, who leads the ruling party in parliament and shares many executive responsibilities, mainly in domestic affairs.[34]
Members of parliament are elected by universal (adult) suffrage based on a modified proportional representation system by district to a six-year term. The primary modification is that, the party that receives the largest number of valid votes in each constituency gains a unique "bonus seat." The president may summon, suspend, or end a legislative session and dissolve Parliament any time after it has served for one year. The parliament reserves the power to make all laws.
On 1 July 1960 the people of Sri Lanka appointed the first-ever female head of government in Prime Minister Sirimavo Bandaranaike. Her daughter Chandrika Kumaratunga served for a short period as the prime minister between August and December 1994 before being elected as the first female president of the country from 1994 to 2005 for 2 consecutive terms. The current president, who took office on 21 November 2005, and has been elected for two consecutive terms, is Mahinda Rajapaksa. The current prime minister, D. M. Jayaratne, took office on 21 April 2010.
Sri Lanka has enjoyed democracy with universal suffrage since 1931. Current politics in Sri Lanka are controlled by rival coalitions led by the left-wing Sri Lanka Freedom Party, headed by President Rajapaksa, the comparatively right-wing United National Party led by former prime minister Ranil Wickremesinghe. There are also many smaller Buddhist, socialist and Tamil nationalist political parties that oppose the separatism of the LTTE but demand regional autonomy and increased civil rights. Since 1948, Sri Lanka has been a member of the Commonwealth of Nations and the United Nations.
It is also a member of the Non-Aligned Movement, the Colombo Plan, Asia-Pacific Economic Cooperation and the South Asian Association for Regional Cooperation. Through the Cold War-era, Sri Lanka followed a foreign policy of non-alignment but has remained closer to the United States and Western Europe.
The military of Sri Lanka comprises the Sri Lankan Army, the Sri Lankan Navy and the Sri Lankan Air Force. These are administered by the Ministry of Defence. During 1971 and 1989 the army assisted the police in government response against the Marxist militants of the JVP and fought the LTTE from 1983 to 2009. Sri Lanka receives considerable military assistance from Pakistan and China.[35]
Foreign relations and military
Foreign relations
Sri Lanka traditionally follows a nonaligned foreign policy but has been seeking closer relations with the United States since December 1977. It participates in multilateral diplomacy, particularly at the United Nations, where it seeks to promote sovereignty, independence, and development in the developing world. Sri Lanka was a founding member of the Non-Aligned Movement (NAM). It also is a member of the Commonwealth, the SAARC, the World Bank, International Monetary Fund, Asian Development Bank, and the Colombo Plan. Sri Lanka continues its active participation in the NAM, while also stressing the importance it places on regionalism by playing a strong role in SAARC.
Military
¬¬
Sri Lanka Air Force IAI Kfir fighter aircraft
The Sri Lanka Armed Forces, comprising the Sri Lanka Army, the Sri Lanka Navy and the Sri Lanka Air Force, comes under the purview of the Ministry of Defence (MoD). The total strength of the three services is around 230,000 active personnel. Sri Lanka does not use a military draft.
In support of the armed forces there are three paramilitary units functioning under purview of the Ministry of Defence, which are the Special Task Force, the Civil Defence Force and the Sri Lanka Coast Guard[36][37]
Since independence from Britain in 1948, the primary focus of the armed forces has been on internal security, due to three major insurgencies, including a 30 year long conflict with the Liberation Tigers of Tamil Eelam which was proscribed as a terrorist organisation by 32 countries. Due to this conflict the armed forces had expanded to its current size and where in a continuous mobilized state for the last 30 years. Unique in modern military history, this was a low intensity conflict which progressed into a bloody conflict which included elements of conventional warfare as well as classic guerrilla and asymmetric warfare, with pitch battles taking place in land and at sea, later briefly moving to the air and unprecedented use of suicide attacks by a violent non-state actor. Although it drew in other regional countries into the conflict directly (India) or indirectly (Pakistan, China); the conflict itself did not result in any territorial or constitutional changes, it resulted in the deaths of 80,000-100,000 people.[38]
In a rare occurrence in modern history the conflict that had 30 years of constant fighting, halted several times briefly by failed peace overtures, ended by a military outcome with a comprehensively defeat of the LTTE May 2009.[39] Since 2002 the Sri Lankan armed forces have also taken part in several peace keeping missions with the UN.
Peace keeping
Even though its armed forces were then engaged in an internal conflict, Sri Lanka contributed with forces in international missions organised by the United Nations, notably the United Nations Stabilization Mission in Haiti and continue to contribute their forces to the United Nations. On 21 October 2009 another group of two hundred Sri Lankan troops including nine officers from all three branches of the armed forces were added to the current deployment in a passing-out parade. The two hundred troops are scheduled to leave for Haiti on 8 November 2009.[40]
Economy
In the 19th and 20th centuries, Sri Lanka became a plantation economy, famous for its production and export of cinnamon, rubber and Ceylon tea, which remains a trademark national export. The development of modern ports under British rule raised the strategic importance of the island as a centre of trade. During World War II, the island hosted important military installations and Allied forces. However, the plantation economy aggravated poverty and economic inequality.
From 1948 to 1977 socialism strongly influenced the government's economic policies. Colonial plantations were dismantled, industries were nationalised and a welfare state established. While the standard of living and literacy improved significantly, the nation's economy suffered from inefficiency, slow growth and lack of foreign investment[citation needed].
From 1977 the UNP government began incorporating privatisation, deregulation and the promotion of private enterprise. While the production and export of tea, rubber, coffee, sugar and other agricultural commodities remains important, the nation has moved steadily towards an industrialised economy with the development of food processing, textiles, telecommunications and finance. By 1996 plantation crops made up only 20% of export, and further declined to 16.8% in 2005 (compared with 93% in 1970), while textiles and garments have reached 63%.
The GDP grew at an average annual rate of 5.5% during the early 1990s, until a drought and a deteriorating security situation lowered growth to 3.8% in 1996. The economy rebounded in 1997–2000, with average growth of 5.3%. The year of 2001 saw the first recession in the country's history, as a result of power shortages, budgetary problems, the global slowdown, and continuing civil strife. Signs of recovery appeared after the 2002 ceasefire which died away following the beginning of war. Since the separatist war ended in May 2009 the Sri Lankan stock market has shown marked gains to be among the 3 best performing markets in the world.[41] The Colombo Stock Exchange reported the highest growth in the world for 2003, and today Sri Lanka has the highest per capita income in South Asia. About 14% of the population live on less than US$ 1.25 per day.[42]
Sri Lanka's most widely known export, Ceylon tea.
In April 2004, there was a sharp reversal in economic policy after the government headed by Ranil Wickremesinghe of the United National Party was defeated by a coalition made up of Sri Lanka Freedom Party and the leftist-nationalist Janatha Vimukthi Peramuna called the United People's Freedom Alliance. The new government stopped the privatisation of state enterprises and reforms of state utilities such as power and petroleum, and embarked on a subsidy program called the Rata Perata economic program. Its main theme to support the rural and suburban SMEs and protect the domestic economy from external influences, such as oil prices, the World Bank and the International Monetary Fund.
Sri Lanka, with an income per head of US$1,972, still lags behind some of its neighbours including Maldives but is ahead of its giant neighbour India. Its economy grew by an average of 5% during the 1990s during the 'War for Peace' era. According to the Sri Lankan central bank statistics, the economy was estimated to have grown by 7% last year, while inflation reached 20%.
Parts of Sri Lanka, particularly the South and East coast, were devastated by the 2004 Asian Tsunami. The economy was briefly buoyed by an influx of foreign aid and tourists, but this was disrupted with the reemergence of the civil war resulting in increased lawlessness in the country[43] and a sharp decline in tourism.[44][45] But following the end of the 3 decade long separatist war in May 2009 tourism has seen a steep uptick. Also the end of war has ensured the rule of law in the whole of the island.
Recently, New York Times has placed Sri Lanka Number 1 in 31 places to go in 2010.[46]
As a result of its location in the path of major sea routes, Sri Lanka is a strategic naval link between West Asia and South East Asia.[12] It has also been a center of the Buddhist religion and culture from ancient times and is one of the few remaining abodes of Buddhism in South Asia along with Ladakh, Bhutan and the Chittagong hill tracts[13] The Sinhalese community forms the majority of the population; Tamils, who are concentrated in the north and east of the island, form the largest ethnic minority. Other communities include Moors, Burghers, Kaffirs, Malays and the aboriginal Vedda people.
The country is famous for the production and export of tea, coffee, coconuts, rubber and cinnamon, the latter which is native to the country.[14] The natural beauty Sri Lanka has led to the title The Pearl of the Indian Ocean, it is full of lush tropical forests, white beaches and diverse landscape throughout along with a rich biodiversity. The country lays claim to a long and colorful history of over three thousand years, having one of the longest documented histories in the world. Sri Lanka's rich culture can be attributed to the many different communities in the island. Sri Lanka is a founding member state of SAARC and a member United Nations, Commonwealth of Nations, G77 and Non-Aligned Movement.
•
The island of Sri Lanka lies in the Indian Ocean, to the southwest of the Bay of Bengal. It is separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait. According to Hindu mythology, a land bridge to the Indian mainland, known as Rama's Bridge, was constructed during the time of Rama by the vanara architect Nala. Often referred to as Adam's Bridge, it now amounts to only a chain of limestone shoals remaining above sea level.[21]
According to colonial British reports, this is a natural causeway which was formerly complete, but was breached by a violent storm in 1480.[22] The island consists mostly of flat-to-rolling coastal plains, with mountains rising only in the south-central part. Amongst these is the highest point Pidurutalagala, reaching 2,524 metres (8,281 ft) above sea level.
The climate of Sri Lanka can be described as tropical and warm. Its position between 5 and 10 north latitude endows the country with a warm climate moderated by ocean winds and considerable moisture. The mean temperature ranges from about 16 °C (60.8 °F) in the Central Highlands, where frost may occur for several days in the winter, to a maximum of approximately 33 °C (91.4 °F) in other low-altitude areas. The average yearly temperature ranges from 28 °C (82.4 °F) to nearly 31 °C (87.8 °F). Day and night temperatures may vary by 4 °C (7.20 °F) to 7 °C (12.60 °F). During the coldest days of January, many people wear coats and sweaters in the highlands and elsewhere.
May, the hottest period, precedes the summer monsoon rains. The rainfall pattern is influenced by monsoon winds from the Indian Ocean and Bay of Bengal: as the winds encounter the mountain slopes of the Central Highlands, they unload heavy rains on the slopes and the southwestern areas of the island. Some of the windward slopes receive up to 2,500 millimetres (98.4 in) of rain each month, but the leeward slopes in the east and northeast receive little rain. Periodic squalls occur and sometimes tropical cyclones bring overcast skies and rains to the southwest, northeast, and eastern parts of the island.
Between December and March, monsoon winds come from the northeast, bringing moisture from the Bay of Bengal. Humidity is typically higher in the southwest and mountainous areas and depends on the seasonal patterns of rainfall, and places like Colombo experience daytime humidity above 70% all year round, rising to almost 90% during the monsoon season in June. Anuradhapura experiences a daytime low of 60% during the monsoon month of March, but a high of 79% during the November and December rains. In the highlands, Kandy's daytime humidity usually ranges between 70% and 79%.
The mountains and the southwestern part of the country, known as the "wet zone", receive ample rainfall at an average of 2,500 mm (98 in). Most of the east, southeast, and northern parts of the
country comprise the "dry zone", which receives between 1,200 mm (47 in) and 1,900 mm (75 in) of rain annually. Much of the rain in these areas falls from October to January; during the rest of the year there is very little precipitation. The arid northwest and southeast coasts receive the least amount of rain at 600 mm (24 in) to 1,200 mm (47 in) per year.
Varieties of flowering acacias are well adapted to the arid conditions and flourish on the Jaffna Peninsula. Among the trees of the dry-land forests, are some valuable species such as satinwood, ebony, ironwood, mahogany and teak. In the wet zone, the dominant vegetation of the lowlands is a tropical evergreen forest, with tall trees, broad foliage, and a dense undergrowth of vines and creepers. Subtropical evergreen forests resembling those of temperate climates flourish in the higher altitudes. Forests at one time covered nearly the entire island, but by the late 20th century lands classified as forests and forest reserves covered around ⅓ of the land.[23]
The Yala National Park in the southeast protects herds of elephant, deer, and peacocks, and the Wilpattu National Park in the northwest preserves the habitats of many water birds, such as storks, pelicans, ibis, and spoonbills. During the Mahaweli Ganga Program of the 1970s and
1980s in northern Sri Lanka, the government set aside four areas of land totalling 1,900 km2 (730 sq mi) as national parks. The island has four biosphere reserves, Bundala, Hurulu Forest Reserve, the Kanneliya-Dediyagala-Nakiyadeniya, and Sinharaja.[24]
The national flower of Sri Lanka is the Nymphaea stellata (Sinhalese Nil Mahanel),[25] the national tree is the Ironwood (Sinhalese Na),[26] and the national bird is the Sri Lanka Junglefowl, which is endemic to the country.[27]
Paleolithic human settlements have been discovered at excavations in several cave sites in the Western Plains region and the South-western face of the Central Hills region. Anthropologists believe that some discovered burial rites and certain decorative artefacts exhibit similarities between the first inhabitants of the island and the early inhabitants of Southern India. Recent bioanthropological studies have however dismissed these links, and have placed the origin of the people to the northern parts of India[citation needed].
One of the first written references to the island is found in the Indian epic Ramayana, which described the emperor Ravana as monarch of the powerful kingdom of Lanka, which was created by the divine sculptor Vishwakarma for Kubera, the treasurer of the Gods.[28] English historian James Emerson Tennent also theorised Galle, a southern city in Sri Lanka, was the ancient seaport of Tarshish from which King Solomon is said to have drawn ivory, peacocks and other valuables. The main written accounts of the country's history are the Buddhist chronicles of Mahavansa and Dipavamsa.
The earliest-known inhabitants of the island now known as Sri Lanka were probably the ancestors of the Wanniyala-Aetto people, also known as Veddahs and numbering roughly 3,000. Linguistic analysis has found a correlation of the Sinhalese language with the languages of the Sindh and Gujarat, although most historians believe that the Sinhala community emerged well after the assimilation of various ethnic groups.
From the ancient period date some remarkable archaeological sites including the ruins of Sigiriya, the so-called "Fortress in the Sky", and huge public works. Among the latter are large "tanks" or reservoirs, important for conserving water in a climate that alternates rainy seasons with dry times, and elaborate aqueducts, some with a slope as finely calibrated as one inch to the mile. Ancient Sri Lanka was also the first in the world to have established a dedicated hospital in Mihintale in the 4th century BCE. Ancient Sri Lanka was also the world's leading exporter of cinnamon, which was exported to Egypt as early as 1400 BCE. Sri Lanka was also the first Asian nation to have a female ruler in Queen Anula (47–42 BC).
Ancient Sri Lanka
Since ancient times Sri Lanka was ruled by monarchs, most notably of the Sinha royal dynasty that lasted over 2000 years. The island was also infrequently invaded by South Indian kingdoms and parts of the island were ruled intermittently by the Chola dynasty, the Pandya dynasty, the Chera dynasty and the Pallava dynasty. The island was also invaded by the kingdoms of Kalinga (modern Orissa) and those from the Malay Peninsula.
Buddhism arrived from India in the 3rd century BCE, brought by Bhikkhu Mahinda, who is believed to have been the son of Mauryan emperor Ashoka. Mahinda's mission won over the Sinhalese monarch Devanampiyatissa of Mihintale, who embraced the faith and propagated it throughout the Sinhalese population. The Buddhist kingdoms of Sri Lanka would maintain a large number of Buddhist schools and monasteries, and support the propagation of Buddhism into Southeast Asia.
Sri Lanka had always been an important port and trading post in the ancient world, and was increasingly frequented by merchant ships from the Middle East, Persia, Burma, Thailand, Malaysia, Indonesia and other parts of Southeast Asia. The islands were known to the first European explorers of South Asia and settled by many groups of Arab and Malay merchants.
A Portuguese colonial mission arrived on the island in 1505 headed by Lourenço de Almeida, the son of Francisco de Almeida. At that point the island consisted of three kingdoms, namely Kandy in the central hills, Kotte at the Western coast, and Yarlpanam (Anglicised Jaffna) in the north. The Dutch arrived in the 17th century. Although much of the coastal regions of the island came under the domain of European powers, the interior, hilly region of the island remained independent, with its capital in Kandy.
The British East India Company took over the coastal regions island controlled by the Dutch in 1796, in 1802 these provinces were declaring a crown colony under direct rule of the British government, therefore the island was not part of the British Raj. The annexation of the Kingdom of Kandy in 1815 by the Kandyan convention, unified the island under British rule.
20th Century and the World Wars
European colonists established a series of cinnamon, sugar, coffee, indigo cultivation followed by tea and rubber plantations and graphite mining. The British also brought a large number of indentured workers from Tamil Nadu to work in the plantation economy. The city of Colombo was developed as the administrative centre and commercial heart with its harbor, and the British established modern schools, colleges, roads and churches that brought Western-style education and culture to the native people.
Increasing grievances over the denial of civil rights, mistreatment and abuse of natives by colonial authorities gave rise to a struggle for independence in the 1930s, when the youth leagues opposed the "Ministers' Memorandum," which asked the colonial authority to increase the powers of the board of ministers without granting popular representation or civil freedoms. Buddhist scholars[citation needed] and the Teetotalist Movement also played a vital role in this time.
During World War II, the island served as an important Allied military base. A large segment of the British and American fleet were deployed on the island, as were tens of thousands of soldiers committed to the war against Japan in Southeast Asia. Majority of Ceylonese forget the war as part of British Commonwealth Forces, and some Ceylonese expatriates in the Far east joined to form a Lanka Regiment in the Indian National Army. There was a plan to transport them to Ceylon by submarine, to lead a liberation struggle there[citation needed], but this was aborted.
Independence
The formal ceremony marking the start of self rule, with the opening of the first parliament at Independence Square.
Following the war, popular pressure for independence intensified. The office of Prime Minister of Ceylon was created in advance of independence on 14 October 1947, Don Stephen Senanayake being the first prime minister. On 4 February 1948 the country gained its independence as the Dominion of Ceylon. The island enjoyed good relations with the United Kingdom and had the British Royal Navy stationed at Trincomalee until 1956. With Solomon Bandaranaike elected as prime minister, Ceylon began moving towards links with the communist bloc.
On 21 July 1960 Sirimavo Bandaranaike took office as prime minister, and became the world's first female prime minister[29] and the first female head of government in post-colonial Asia. During her second term as prime minister, her government instituted socialist economic polices and strengthened ties with the USSR and later China, while promoting a policy of non-alignment. However in 1971, Ceylon experienced a Marxist insurrection, which was quickly suppressed with international support. In 1972, with the adaptation of a new constitution, the country became a republic changing its name to Sri Lanka and remained a member of the Commonwealth of Nations.
Civil war
One of the aspects of the independence movement was that it was very much a Sinhalese movement[citation needed]. As a result, the Sinhalese majority attempted to remodel Sri Lanka as a Sinhalese nation-state[citation needed]. The lion in the national flag is derived from the banner of the last Sinhalese Kingdom, which, to the Sinhalese majority, is a symbol of their fight against British colonialism. One single strip of orange on the left part of the flag represents the Tamil population, and it is seen by many Tamil as a symbol of their marginalisation.[citation needed][30]
In 1956, the Official Language Act (commonly referred to as The Sinhala Only Act) was enacted. The law mandated Sinhala, the language of Sri Lanka's majority Sinhalese community, which is spoken by over 70% of Sri Lanka's population, as the sole official language of Sri Lanka. Supporters of the law saw it as an attempt by a community that had just gained independence to distance themselves from their colonial masters.
The immediate (and intended)[citation needed] consequence of this act was to force large numbers of Tamil who worked in the civil service, and who could not meet this language requirement, to resign. An attempt to make Buddhism the national religion, to the exclusion of Hindu and Islam, was also made.[citation needed] Affirmative action in favour of Sinhalese was also instituted, ostensibly to reverse colonial discrimination against Sinhalese in favour of Tamil. Many Tamil[who?], in response to this deliberate marginalisation, came to believe that they deserved a separate nation-state for themselves.[citation needed]
From 1983 to 2009, there was an on-and-off civil war against the government by the Liberation Tigers of Tamil Eelam (LTTE), a separatist militant organisation who fought to create an independent state named Tamil Eelam in the North and East of the island. Both the Sri Lankan government and LTTE have been accused of various human rights violations.[citation needed]
On 19 May 2009, the President of Sri Lanka officially claimed an end to the insurgency and the defeat of the LTTE, following the death of Velupillai Prabhakaran and much of the LTTE's other senior leadership.[31]
Post War
With the end of the war, the government of Sri Lanka called for redevelopment of the nation. The final stages of the war left some 300,000 people displaced.[32] By 2 May 2010, 214,227 IDPs (74%) had been released or returned to their places of origin.[33]
Government and politics
The Supreme Court of Sri Lanka, Colombo.
The Constitution of Sri Lanka establishes a democratic, socialist republic in Sri Lanka, which is also a unitary state. The government is a mixture of the presidential system and the parliamentary system. The President of Sri Lanka is the head of state, the commander in chief of the armed forces, as well as head of government, and is popularly elected for a six-year term.
In the exercise of duties, the President is responsible to the Parliament of Sri Lanka, which is a unicameral 225-member legislature[citation needed]. The President appoints and heads a cabinet of ministers composed of elected members of parliament. The President's deputy is the Prime Minister, who leads the ruling party in parliament and shares many executive responsibilities, mainly in domestic affairs.[34]
Members of parliament are elected by universal (adult) suffrage based on a modified proportional representation system by district to a six-year term. The primary modification is that, the party that receives the largest number of valid votes in each constituency gains a unique "bonus seat." The president may summon, suspend, or end a legislative session and dissolve Parliament any time after it has served for one year. The parliament reserves the power to make all laws.
On 1 July 1960 the people of Sri Lanka appointed the first-ever female head of government in Prime Minister Sirimavo Bandaranaike. Her daughter Chandrika Kumaratunga served for a short period as the prime minister between August and December 1994 before being elected as the first female president of the country from 1994 to 2005 for 2 consecutive terms. The current president, who took office on 21 November 2005, and has been elected for two consecutive terms, is Mahinda Rajapaksa. The current prime minister, D. M. Jayaratne, took office on 21 April 2010.
Sri Lanka has enjoyed democracy with universal suffrage since 1931. Current politics in Sri Lanka are controlled by rival coalitions led by the left-wing Sri Lanka Freedom Party, headed by President Rajapaksa, the comparatively right-wing United National Party led by former prime minister Ranil Wickremesinghe. There are also many smaller Buddhist, socialist and Tamil nationalist political parties that oppose the separatism of the LTTE but demand regional autonomy and increased civil rights. Since 1948, Sri Lanka has been a member of the Commonwealth of Nations and the United Nations.
It is also a member of the Non-Aligned Movement, the Colombo Plan, Asia-Pacific Economic Cooperation and the South Asian Association for Regional Cooperation. Through the Cold War-era, Sri Lanka followed a foreign policy of non-alignment but has remained closer to the United States and Western Europe.
The military of Sri Lanka comprises the Sri Lankan Army, the Sri Lankan Navy and the Sri Lankan Air Force. These are administered by the Ministry of Defence. During 1971 and 1989 the army assisted the police in government response against the Marxist militants of the JVP and fought the LTTE from 1983 to 2009. Sri Lanka receives considerable military assistance from Pakistan and China.[35]
Foreign relations and military
Foreign relations
Sri Lanka traditionally follows a nonaligned foreign policy but has been seeking closer relations with the United States since December 1977. It participates in multilateral diplomacy, particularly at the United Nations, where it seeks to promote sovereignty, independence, and development in the developing world. Sri Lanka was a founding member of the Non-Aligned Movement (NAM). It also is a member of the Commonwealth, the SAARC, the World Bank, International Monetary Fund, Asian Development Bank, and the Colombo Plan. Sri Lanka continues its active participation in the NAM, while also stressing the importance it places on regionalism by playing a strong role in SAARC.
Military
¬¬
Sri Lanka Air Force IAI Kfir fighter aircraft
The Sri Lanka Armed Forces, comprising the Sri Lanka Army, the Sri Lanka Navy and the Sri Lanka Air Force, comes under the purview of the Ministry of Defence (MoD). The total strength of the three services is around 230,000 active personnel. Sri Lanka does not use a military draft.
In support of the armed forces there are three paramilitary units functioning under purview of the Ministry of Defence, which are the Special Task Force, the Civil Defence Force and the Sri Lanka Coast Guard[36][37]
Since independence from Britain in 1948, the primary focus of the armed forces has been on internal security, due to three major insurgencies, including a 30 year long conflict with the Liberation Tigers of Tamil Eelam which was proscribed as a terrorist organisation by 32 countries. Due to this conflict the armed forces had expanded to its current size and where in a continuous mobilized state for the last 30 years. Unique in modern military history, this was a low intensity conflict which progressed into a bloody conflict which included elements of conventional warfare as well as classic guerrilla and asymmetric warfare, with pitch battles taking place in land and at sea, later briefly moving to the air and unprecedented use of suicide attacks by a violent non-state actor. Although it drew in other regional countries into the conflict directly (India) or indirectly (Pakistan, China); the conflict itself did not result in any territorial or constitutional changes, it resulted in the deaths of 80,000-100,000 people.[38]
In a rare occurrence in modern history the conflict that had 30 years of constant fighting, halted several times briefly by failed peace overtures, ended by a military outcome with a comprehensively defeat of the LTTE May 2009.[39] Since 2002 the Sri Lankan armed forces have also taken part in several peace keeping missions with the UN.
Peace keeping
Even though its armed forces were then engaged in an internal conflict, Sri Lanka contributed with forces in international missions organised by the United Nations, notably the United Nations Stabilization Mission in Haiti and continue to contribute their forces to the United Nations. On 21 October 2009 another group of two hundred Sri Lankan troops including nine officers from all three branches of the armed forces were added to the current deployment in a passing-out parade. The two hundred troops are scheduled to leave for Haiti on 8 November 2009.[40]
Economy
In the 19th and 20th centuries, Sri Lanka became a plantation economy, famous for its production and export of cinnamon, rubber and Ceylon tea, which remains a trademark national export. The development of modern ports under British rule raised the strategic importance of the island as a centre of trade. During World War II, the island hosted important military installations and Allied forces. However, the plantation economy aggravated poverty and economic inequality.
From 1948 to 1977 socialism strongly influenced the government's economic policies. Colonial plantations were dismantled, industries were nationalised and a welfare state established. While the standard of living and literacy improved significantly, the nation's economy suffered from inefficiency, slow growth and lack of foreign investment[citation needed].
From 1977 the UNP government began incorporating privatisation, deregulation and the promotion of private enterprise. While the production and export of tea, rubber, coffee, sugar and other agricultural commodities remains important, the nation has moved steadily towards an industrialised economy with the development of food processing, textiles, telecommunications and finance. By 1996 plantation crops made up only 20% of export, and further declined to 16.8% in 2005 (compared with 93% in 1970), while textiles and garments have reached 63%.
The GDP grew at an average annual rate of 5.5% during the early 1990s, until a drought and a deteriorating security situation lowered growth to 3.8% in 1996. The economy rebounded in 1997–2000, with average growth of 5.3%. The year of 2001 saw the first recession in the country's history, as a result of power shortages, budgetary problems, the global slowdown, and continuing civil strife. Signs of recovery appeared after the 2002 ceasefire which died away following the beginning of war. Since the separatist war ended in May 2009 the Sri Lankan stock market has shown marked gains to be among the 3 best performing markets in the world.[41] The Colombo Stock Exchange reported the highest growth in the world for 2003, and today Sri Lanka has the highest per capita income in South Asia. About 14% of the population live on less than US$ 1.25 per day.[42]
Sri Lanka's most widely known export, Ceylon tea.
In April 2004, there was a sharp reversal in economic policy after the government headed by Ranil Wickremesinghe of the United National Party was defeated by a coalition made up of Sri Lanka Freedom Party and the leftist-nationalist Janatha Vimukthi Peramuna called the United People's Freedom Alliance. The new government stopped the privatisation of state enterprises and reforms of state utilities such as power and petroleum, and embarked on a subsidy program called the Rata Perata economic program. Its main theme to support the rural and suburban SMEs and protect the domestic economy from external influences, such as oil prices, the World Bank and the International Monetary Fund.
Sri Lanka, with an income per head of US$1,972, still lags behind some of its neighbours including Maldives but is ahead of its giant neighbour India. Its economy grew by an average of 5% during the 1990s during the 'War for Peace' era. According to the Sri Lankan central bank statistics, the economy was estimated to have grown by 7% last year, while inflation reached 20%.
Parts of Sri Lanka, particularly the South and East coast, were devastated by the 2004 Asian Tsunami. The economy was briefly buoyed by an influx of foreign aid and tourists, but this was disrupted with the reemergence of the civil war resulting in increased lawlessness in the country[43] and a sharp decline in tourism.[44][45] But following the end of the 3 decade long separatist war in May 2009 tourism has seen a steep uptick. Also the end of war has ensured the rule of law in the whole of the island.
Recently, New York Times has placed Sri Lanka Number 1 in 31 places to go in 2010.[46]
Nature
NATURE
Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic.
The word nature is derived from the Latin word natura, or "essential qualities, innate disposition", and in ancient times, literally meant "birth".[1] Natura was a Latin translation of the Greek word physis (φύσις), which originally related to the intrinsic characteristics that plants, animals, and other features of the world develop of their own accord.[2][3] The concept of nature as a whole, the physical universe, is one of several expansions of the original notion; it began with certain core applications of the word φύσις by pre-Socratic philosophers, and has steadily gained currency ever since. This usage was confirmed during the advent of modern scientific method in the last several centuries.[4][5]
Within the various uses of the word today, "nature" may refer to the general realm of various types of living plants and animals, and in some cases to the processes associated with inanimate objects–the way that particular types of things exist and change of their own accord, such as the weather and geology of the Earth, and the matter and energy of which all these things are composed. It is often taken to mean the "natural environment" or wilderness–wild animals, rocks, forest, beaches, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention. For, example, manufactured objects and human interaction generally are not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature". This more traditional concept of natural things which can still be found today implies a distinction between the natural and the artificial, with the artificial being understood as that which has been brought into being by a human consciousness or a human mind. Depending on the particular context, the term "natural" might also be distinguished from the unnatural, the supernatural, and the artifactual.
GEOLOGY
Earth (or, "the earth") is the only planet presently known to support life, and its natural features are the subject of many fields of scientific research. Within the solar system, it is third nearest to the sun; it is the largest terrestrial planet and the fifth largest overall. Its most prominent climatic features are its two large polar regions, two relatively narrow temperate zones, and a wide equatorial tropical to subtropical region.[6] Precipitation varies widely with location, from several metres of water per year to less than a millimetre. 71 percent of the Earth's surface is covered by salt-water oceans. The remainder consists of continents and islands, with most of the inhabited land in the Northern Hemisphere.
Earth has evolved through geological and biological processes that have left traces of the original conditions. The outer surface is divided into several gradually migrating tectonic plates, which have changed relatively quickly several times.[citation needed] The interior remains active, with a thick layer of molten mantle and an iron-filled core that generates a magnetic field.
The atmospheric conditions have been significantly altered from the original conditions by the presence of life-forms,[7] which create an ecological balance that stabilizes the surface conditions. Despite the wide regional variations in climate by latitude and other geographic factors, the long-term average global climate is quite stable during interglacial periods,[8] and variations of a degree or two of average global temperature have historically had major effects on the ecological balance, and on the actual geography of the Earth.[9][10]
Earth's atmosphere, Climate, and Weather
The atmosphere of the Earth serves as a key factor in sustaining the planetary ecosystem. The thin layer of gases that envelops the Earth is held in place by the planet's gravity. Dry air consists of 78% nitrogen, 21% oxygen, 1% argon and other inert gases, carbon dioxide, etc.; but air also contains a variable amount of water vapor. The atmospheric pressure declines steadily with altitude, and has a scale height of about 8 kilometres at the Earth's surface: the height at which the atmospheric pressure has declined by a factor of e (a mathematical constant equal to 2.71...).[24][25] The ozone layer of the Earth's atmosphere plays an important role in depleting the amount of ultraviolet (UV) radiation that reaches the surface. As DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.
Terrestrial weather occurs almost exclusively in the lower part of the atmosphere, and serves as a convective system for redistributing heat. Ocean currents are another important factor in determining climate, particularly the major underwater thermohaline circulation which distributes heat energy from the equatorial oceans to the polar regions. These currents help to moderate the differences in temperature between winter and summer in the temperate zones. Also, without the redistributions of heat energy by the ocean currents and atmosphere, the tropics would be much hotter, and the polar regions much colder.
Weather can have both beneficial and harmful effects. Extremes in weather, such as tornadoes or hurricanes and cyclones, can expend large amounts of energy along their paths, and produce devastation. Surface vegetation has evolved a dependence on the seasonal variation of the weather, and sudden changes lasting only a few years can have a dramatic effect, both on the vegetation and on the animals which depend on its growth for their food.
A tornado in central Oklahoma.
The planetary climate is a measure of the long-term trends in the weather. Various factors are known to influence the climate, including ocean currents, surface albedo, greenhouse gases, variations in the solar luminosity, and changes to the planet's orbit. Based on historical records, the Earth is known to have undergone drastic climate changes in the past, including ice ages.
The climate of a region depends on a number of factors, especially latitude. A latitudinal band of the surface with similar climatic attributes forms a climate region. There are a number of such regions, ranging from the tropical climate at the equator to the polar climate in the northern and southern extremes. Weather is also influenced by the seasons, which result from the Earth's axis being tilted relative to its orbital plane. Thus, at any given time during the summer or winter, one part of the planet is more directly exposed to the rays of the sun. This exposure alternates as the Earth revolves in its orbit. At any given time, regardless of season, the northern and southern hemispheres experience opposite seasons.
Weather is a chaotic system that is readily modified by small changes to the environment, so accurate weather forecasting is currently limited to only a few days.[citation needed] Overall, two things are currently happening worldwide: (1) temperature is increasing on the average; and (2) regional climates have been undergoing noticeable changes.[26]
WATER
Water is a chemical substance that is composed of hydrogen and oxygen and is vital for all known forms of life.[27] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface.[28] On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation.[29] Oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. Additionally, a minute amount of the Earth's water is contained within biological bodies and manufactured products.
OCEAN
In ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (an area of some 361 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean.[30][31] This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography.[32]
The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria: these divisions are (in descending order of size) the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the Arctic Ocean. Smaller regions of the oceans are called seas, gulfs, bays and other names. There are also salt lakes, which are smaller bodies of landlocked saltwater that are not interconnected with the World Ocean. Two notable examples of salt lakes are the Aral Sea and the Great Salt Lake.
LAKE
A lake (from Latin lacus) is a terrain feature (or physical feature), a body of liquid on the surface of a world that is localized to the bottom of basin (another type of landform or terrain feature; that is, it is not global) and moves slowly if it moves at all. On Earth, a body of water is considered a lake when it is inland, not part of the ocean, is larger and deeper than a pond, and is fed by a river.[33][34] The only world other than Earth known to harbor lakes is Titan, Saturn's largest moon, which has lakes of ethane, most likely mixed with methane. It is not known if Titan's lakes are fed by rivers, though Titan's surface is carved by numerous river beds. Natural lakes on Earth are generally found in mountainous areas, rift zones, and areas with ongoing or recent glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world, there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.
[edit] Ponds
The Westborough Reservoir (Mill Pond) in Westborough, Massachusetts.
POND
A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding, and solar ponds designed to store thermal energy. Ponds and lakes are distinguished from streams via current speed. While currents in streams are easily observed, ponds and lakes possess thermally driven microcurrents and moderate wind driven currents. These features distinguish a pond from many other aquatic terrain features, such as stream pools and tide pools.
RIVER
A river is a natural watercourse,[35] usually freshwater, flowing toward an ocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including stream, creek, brook, rivulet, and rill; there is no general rule that defines what can be called a river. Many names for small rivers are specific to geographic location; one example is Burn in Scotland and North-east England. Sometimes a river is said to be larger than a creek,[36] but this is not always the case, due to vagueness in the language.[37] A river is part of the hydrological cycle. Water within a river is generally collected from precipitation through surface runoff, groundwater recharge, springs, and the release of stored water in natural ice and snowpacks (i.e., from glaciers).
STREAM
A stream is a flowing body of water with a current, confined within a bed and stream banks. In the United States a stream is classified as a watercourse less than 60 feet (18 metres) wide. Streams are important as conduits in the water cycle, instruments in groundwater recharge, and they serve as corridors for fish and wildlife migration. The biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity. The study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography.[38]
Main articles: Ecology and Ecosystem
Ecosystems are composed of a variety of abiotic and biotic components that function in an interrelated way.[40] The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are: soil, atmosphere, radiation from the sun, water, and living organisms.
Central to the ecosystem concept is the idea that living organisms interact with every other element in their local environment. Eugene Odum, a founder of ecology, stated: "Any unit that includes all of the organisms (ie: the "community") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e.: exchange of materials between living and nonliving parts) within the system is an ecosystem."[41] Within the ecosystem, species are connected and dependent upon one another in the food chain, and exchange energy and matter between themselves as well as with their environment.[42] The human ecosystem concept is grounded in the deconstruction of the human/nature dichotomy and the premise that all species are ecologically integrated with each other, as well as with the abiotic constituents of their biotope.[citation needed]
A smaller unit of size is called a microecosystem. For example, a microsystem can be a stone and all the life under it. A macroecosystem might involve a whole ecoregion, with its drainage basin.[43]
Wilderness
Wilderness is generally defined as areas that have not been significantly modified by human activity. The WILD Foundation goes into more detail, defining wilderness as: "The most intact, undisturbed wild natural areas left on our planet - those last truly wild places that humans do not control and have not developed with roads, pipelines or other industrial infrastructure." Wilderness areas can be found in preserves, estates, farms, conservation preserves, ranches, National Forests, National Parks and even in urban areas along rivers, gulches or otherwise undeveloped areas. Wilderness areas and protected parks are considered important for the survival of certain species, ecological studies, conservation, solitude, and recreation. Some nature writers believe wilderness areas are vital for the human spirit and creativity,[44] and some Ecologists consider wilderness areas to be an integral part of the planet's self-sustaining natural ecosystem (the biosphere). They may also preserve historic genetic traits and that they provide habitat for wild flora and fauna that may be difficult to recreate in zoos, arboretums or laboratories.
Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction.[45] Life may also be said to be simply the characteristic state of organisms.
Properties common to terrestrial organisms (plants, animals, fungi, protists, archaea and bacteria) are that they are cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, and reproduce. An entity with these properties is generally considered life. However, not every definition of life considers all of these properties to be essential. Human-made analogs of life may also be considered to be life.
The biosphere is the part of Earth's outer shell – including land, surface rocks, water, air and the atmosphere – within which life occurs, and which biotic processes in turn alter or transform. From the broadest geophysiological 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 (rocks), hydrosphere (water), and atmosphere (air). Currently the entire Earth contains over 75 billion tons (150 trillion pounds or about 6.8 x 1013 kilograms) of biomass (life), which lives within various environments within the biosphere.[46]
Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence.[47] More than 2 million species of plant and animal life have been identified to date,[48] and estimates of the actual number of existing species range from several million to well over 50 million.[49][50][51] The number of individual species of life is constantly in some degree of flux, with new species appearing and others ceasing to exist on a continual basis.[52][53] The total number of species is presently in rapid decline.[54][55][56]
Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic.
The word nature is derived from the Latin word natura, or "essential qualities, innate disposition", and in ancient times, literally meant "birth".[1] Natura was a Latin translation of the Greek word physis (φύσις), which originally related to the intrinsic characteristics that plants, animals, and other features of the world develop of their own accord.[2][3] The concept of nature as a whole, the physical universe, is one of several expansions of the original notion; it began with certain core applications of the word φύσις by pre-Socratic philosophers, and has steadily gained currency ever since. This usage was confirmed during the advent of modern scientific method in the last several centuries.[4][5]
Within the various uses of the word today, "nature" may refer to the general realm of various types of living plants and animals, and in some cases to the processes associated with inanimate objects–the way that particular types of things exist and change of their own accord, such as the weather and geology of the Earth, and the matter and energy of which all these things are composed. It is often taken to mean the "natural environment" or wilderness–wild animals, rocks, forest, beaches, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention. For, example, manufactured objects and human interaction generally are not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature". This more traditional concept of natural things which can still be found today implies a distinction between the natural and the artificial, with the artificial being understood as that which has been brought into being by a human consciousness or a human mind. Depending on the particular context, the term "natural" might also be distinguished from the unnatural, the supernatural, and the artifactual.
GEOLOGY
Earth (or, "the earth") is the only planet presently known to support life, and its natural features are the subject of many fields of scientific research. Within the solar system, it is third nearest to the sun; it is the largest terrestrial planet and the fifth largest overall. Its most prominent climatic features are its two large polar regions, two relatively narrow temperate zones, and a wide equatorial tropical to subtropical region.[6] Precipitation varies widely with location, from several metres of water per year to less than a millimetre. 71 percent of the Earth's surface is covered by salt-water oceans. The remainder consists of continents and islands, with most of the inhabited land in the Northern Hemisphere.
Earth has evolved through geological and biological processes that have left traces of the original conditions. The outer surface is divided into several gradually migrating tectonic plates, which have changed relatively quickly several times.[citation needed] The interior remains active, with a thick layer of molten mantle and an iron-filled core that generates a magnetic field.
The atmospheric conditions have been significantly altered from the original conditions by the presence of life-forms,[7] which create an ecological balance that stabilizes the surface conditions. Despite the wide regional variations in climate by latitude and other geographic factors, the long-term average global climate is quite stable during interglacial periods,[8] and variations of a degree or two of average global temperature have historically had major effects on the ecological balance, and on the actual geography of the Earth.[9][10]
Earth's atmosphere, Climate, and Weather
The atmosphere of the Earth serves as a key factor in sustaining the planetary ecosystem. The thin layer of gases that envelops the Earth is held in place by the planet's gravity. Dry air consists of 78% nitrogen, 21% oxygen, 1% argon and other inert gases, carbon dioxide, etc.; but air also contains a variable amount of water vapor. The atmospheric pressure declines steadily with altitude, and has a scale height of about 8 kilometres at the Earth's surface: the height at which the atmospheric pressure has declined by a factor of e (a mathematical constant equal to 2.71...).[24][25] The ozone layer of the Earth's atmosphere plays an important role in depleting the amount of ultraviolet (UV) radiation that reaches the surface. As DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.
Terrestrial weather occurs almost exclusively in the lower part of the atmosphere, and serves as a convective system for redistributing heat. Ocean currents are another important factor in determining climate, particularly the major underwater thermohaline circulation which distributes heat energy from the equatorial oceans to the polar regions. These currents help to moderate the differences in temperature between winter and summer in the temperate zones. Also, without the redistributions of heat energy by the ocean currents and atmosphere, the tropics would be much hotter, and the polar regions much colder.
Weather can have both beneficial and harmful effects. Extremes in weather, such as tornadoes or hurricanes and cyclones, can expend large amounts of energy along their paths, and produce devastation. Surface vegetation has evolved a dependence on the seasonal variation of the weather, and sudden changes lasting only a few years can have a dramatic effect, both on the vegetation and on the animals which depend on its growth for their food.
A tornado in central Oklahoma.
The planetary climate is a measure of the long-term trends in the weather. Various factors are known to influence the climate, including ocean currents, surface albedo, greenhouse gases, variations in the solar luminosity, and changes to the planet's orbit. Based on historical records, the Earth is known to have undergone drastic climate changes in the past, including ice ages.
The climate of a region depends on a number of factors, especially latitude. A latitudinal band of the surface with similar climatic attributes forms a climate region. There are a number of such regions, ranging from the tropical climate at the equator to the polar climate in the northern and southern extremes. Weather is also influenced by the seasons, which result from the Earth's axis being tilted relative to its orbital plane. Thus, at any given time during the summer or winter, one part of the planet is more directly exposed to the rays of the sun. This exposure alternates as the Earth revolves in its orbit. At any given time, regardless of season, the northern and southern hemispheres experience opposite seasons.
Weather is a chaotic system that is readily modified by small changes to the environment, so accurate weather forecasting is currently limited to only a few days.[citation needed] Overall, two things are currently happening worldwide: (1) temperature is increasing on the average; and (2) regional climates have been undergoing noticeable changes.[26]
WATER
Water is a chemical substance that is composed of hydrogen and oxygen and is vital for all known forms of life.[27] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface.[28] On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation.[29] Oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. Additionally, a minute amount of the Earth's water is contained within biological bodies and manufactured products.
OCEAN
In ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (an area of some 361 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean.[30][31] This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography.[32]
The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria: these divisions are (in descending order of size) the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the Arctic Ocean. Smaller regions of the oceans are called seas, gulfs, bays and other names. There are also salt lakes, which are smaller bodies of landlocked saltwater that are not interconnected with the World Ocean. Two notable examples of salt lakes are the Aral Sea and the Great Salt Lake.
LAKE
A lake (from Latin lacus) is a terrain feature (or physical feature), a body of liquid on the surface of a world that is localized to the bottom of basin (another type of landform or terrain feature; that is, it is not global) and moves slowly if it moves at all. On Earth, a body of water is considered a lake when it is inland, not part of the ocean, is larger and deeper than a pond, and is fed by a river.[33][34] The only world other than Earth known to harbor lakes is Titan, Saturn's largest moon, which has lakes of ethane, most likely mixed with methane. It is not known if Titan's lakes are fed by rivers, though Titan's surface is carved by numerous river beds. Natural lakes on Earth are generally found in mountainous areas, rift zones, and areas with ongoing or recent glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world, there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.
[edit] Ponds
The Westborough Reservoir (Mill Pond) in Westborough, Massachusetts.
POND
A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding, and solar ponds designed to store thermal energy. Ponds and lakes are distinguished from streams via current speed. While currents in streams are easily observed, ponds and lakes possess thermally driven microcurrents and moderate wind driven currents. These features distinguish a pond from many other aquatic terrain features, such as stream pools and tide pools.
RIVER
A river is a natural watercourse,[35] usually freshwater, flowing toward an ocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including stream, creek, brook, rivulet, and rill; there is no general rule that defines what can be called a river. Many names for small rivers are specific to geographic location; one example is Burn in Scotland and North-east England. Sometimes a river is said to be larger than a creek,[36] but this is not always the case, due to vagueness in the language.[37] A river is part of the hydrological cycle. Water within a river is generally collected from precipitation through surface runoff, groundwater recharge, springs, and the release of stored water in natural ice and snowpacks (i.e., from glaciers).
STREAM
A stream is a flowing body of water with a current, confined within a bed and stream banks. In the United States a stream is classified as a watercourse less than 60 feet (18 metres) wide. Streams are important as conduits in the water cycle, instruments in groundwater recharge, and they serve as corridors for fish and wildlife migration. The biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity. The study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography.[38]
Main articles: Ecology and Ecosystem
Ecosystems are composed of a variety of abiotic and biotic components that function in an interrelated way.[40] The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are: soil, atmosphere, radiation from the sun, water, and living organisms.
Central to the ecosystem concept is the idea that living organisms interact with every other element in their local environment. Eugene Odum, a founder of ecology, stated: "Any unit that includes all of the organisms (ie: the "community") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e.: exchange of materials between living and nonliving parts) within the system is an ecosystem."[41] Within the ecosystem, species are connected and dependent upon one another in the food chain, and exchange energy and matter between themselves as well as with their environment.[42] The human ecosystem concept is grounded in the deconstruction of the human/nature dichotomy and the premise that all species are ecologically integrated with each other, as well as with the abiotic constituents of their biotope.[citation needed]
A smaller unit of size is called a microecosystem. For example, a microsystem can be a stone and all the life under it. A macroecosystem might involve a whole ecoregion, with its drainage basin.[43]
Wilderness
Wilderness is generally defined as areas that have not been significantly modified by human activity. The WILD Foundation goes into more detail, defining wilderness as: "The most intact, undisturbed wild natural areas left on our planet - those last truly wild places that humans do not control and have not developed with roads, pipelines or other industrial infrastructure." Wilderness areas can be found in preserves, estates, farms, conservation preserves, ranches, National Forests, National Parks and even in urban areas along rivers, gulches or otherwise undeveloped areas. Wilderness areas and protected parks are considered important for the survival of certain species, ecological studies, conservation, solitude, and recreation. Some nature writers believe wilderness areas are vital for the human spirit and creativity,[44] and some Ecologists consider wilderness areas to be an integral part of the planet's self-sustaining natural ecosystem (the biosphere). They may also preserve historic genetic traits and that they provide habitat for wild flora and fauna that may be difficult to recreate in zoos, arboretums or laboratories.
Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction.[45] Life may also be said to be simply the characteristic state of organisms.
Properties common to terrestrial organisms (plants, animals, fungi, protists, archaea and bacteria) are that they are cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, and reproduce. An entity with these properties is generally considered life. However, not every definition of life considers all of these properties to be essential. Human-made analogs of life may also be considered to be life.
The biosphere is the part of Earth's outer shell – including land, surface rocks, water, air and the atmosphere – within which life occurs, and which biotic processes in turn alter or transform. From the broadest geophysiological 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 (rocks), hydrosphere (water), and atmosphere (air). Currently the entire Earth contains over 75 billion tons (150 trillion pounds or about 6.8 x 1013 kilograms) of biomass (life), which lives within various environments within the biosphere.[46]
Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence.[47] More than 2 million species of plant and animal life have been identified to date,[48] and estimates of the actual number of existing species range from several million to well over 50 million.[49][50][51] The number of individual species of life is constantly in some degree of flux, with new species appearing and others ceasing to exist on a continual basis.[52][53] The total number of species is presently in rapid decline.[54][55][56]
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