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Old Tuesday, January 29, 2008
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Post Organisms (common to all living things)

Organisms have the potential to carry out the life processes of nutrition, movement, growth, reproduction, respiration, sensitivity and excretion

The following characteristics are those that most biologists accept as being common to all living things. It is true that they may not always be displayed but even the most inactive of organisms has the potential to carry out all these functions. It is equally true that there are times in the life cycles of some organisms where all these functions appear to be suspended as is the case with seed producing organisms (Lotus seeds have been grown after being stored for 160 years).

Movement


Living things move in a directed and controlled way, moving of their own accord. Non-living things only move if they are pushed or pulled by something else. The majority of animals usually move their whole bodies often supported by specialized organs such as fins, wings and legs. These are called locomotors organs moving the animal from place to place.

Plant movement is not locomotors and does not generally involve moving the whole body. Leaves turning towards the light or shoots growing upwards whatever the orientation of the rest of the plant are examples of how plants move. These movements are generally very slow and not always obvious.

Growth


Living things grow. Most animals grow until they reach maturity and then remain at a constant size while plants usually continue to increase in size throughout their life span. It is important to recognize that growth is a permanent increase in measurable features such as volume, mass and length. Cells increase in number by dividing in a process called mitosis (making genetically exact copies). As the soft tissues increase, so there will be associated increase in size of skeletal support tissue such as bone, shell and wood.

When maturity is reached in animal’s cell division continues only at a level to maintain consistent size and to repair loss through damage. Putting on weight as a result of over-eating is not considered to be biological growth in this context

Reproduction


Living things are able to reproduce themselves. If organisms fail to do this, populations will diminish and disappear as their members die from old age, disease, accidents, predation, etc. It is a fundamental law of biology that other living things can only produce living things; every living organism owes its existence to the reproductive activities of other organisms.

This is contrary to the misconceived ideas of spontaneous generation, which some people held in the past. The notion that cockroaches were formed out of crumbs on the bakery floor, that mould was formed out of decaying bread and that rotting sacks of grain turned into mice are examples of how spontaneous generation was thought to operate. Today, these ideas are discredited but they still often provide the stimulus for works of dramatic fiction.

Respiration


Living things respire. Respiration is a complex sequence of chemical reactions, which result in the release of energy from food. There are two types of respiratory process.

Aerobic respiration


Carried out by the vast majority of organisms, this involves oxygen. The by-products of the reaction are water and carbon dioxide both of which are eliminated as waste products. Oxygen is obtained from the air or water using organs designed to optimize gaseous exchange. These include the stomata in plants (small, size regulated pores), spiracles in arthropods, gills in fish and lungs in mammals. The uptake of oxygen and simultaneous elimination of carbon dioxide and water is commonly referred to as breathing. It is important to distinguish between breathing and respiration. It is tempting; particularly with younger children to use the well used term breathing as an all-embracing description of the respiratory process. However, this is not correct and could lead to the reinforcement of misconceptions.


Anaerobic respiration


When oxygen levels are at a low level, it is possible for some simpler organisms and parts of more complex ones to release energy from food without oxygen. This is a far less efficient process but a necessary alternative in some cases. The by-products of anaerobic respiration are different to aerobic. In humans, oxygen starved muscle cells will respire anaerobically under stress such as heavy physical activity. The by-product of this is lactic acid and it is this that causes the puffed out feeling. Yeast cells respire anaerobically in sugar solution producing alcohol as the by-product






Sensitivity


Living things are sensitive to their environment. This means that they detect and respond to events in the world around them. Simple uni-cellular organisms such as Amoeba have limited sensitivity, while higher organisms such as mammals are more sensitive and can react to very small changes in light, sound, touch, taste, smell, temperature, etc.

In higher animals specific organs are developed for the purpose of detecting stimuli. The organization of light sensitive cells into eyes of varying complexity from one species to another is an example.

Plants do not have sensory organs as such but there are clearly certain regions of their bodies such as the shoot tip that are sensitive to light, gravity, water and various chemicals.

Excretion


Living things excrete. Excretion is the removal from the body of waste products which result from normal life processes. Waste products such as carbon dioxide must be removed. If they are allowed to accumulate they cause poisoning which slows down vital chemical reactions. When excretory organs such as kidneys are damaged, the organism quickly displays symptoms of poisoning and death is rapid unless treated.

Excretion should not be confused with egestion, which is the removal from the body of substances with no food value that have passed unused through the digestive systems.

Feeding


Living things feed. Food is the material from which organisms through respiration obtain the energy required to sustain life and carry out all the other defining functions of living things. Food also provides the raw materials for growth and repair. The study of food and feeding is called nutrition.

There are two types of nutrition:

Autotrophic organisms make their own food by a process called photosynthesis. Green plants, for example, manufacture sugar and starch from carbon dioxide and water using the energy of sunlight to drive the necessary chemical reactions

Heterotrophic nutrition
Heterotrophic organisms obtain their food from the bodies of other organisms.

This is done in various ways.

Herbivores such as cattle, tortoises and sparrows eat plants.
Carnivores such as lions, crocodiles, sharks and kestrels eat the flesh of other animals.

Omnivores such as humans can eat both plants and animals.

Saprophytes such as many types of fungi and bacteria, obtain their food in liquid form from the remains of dead organisms. This feeding manifests itself as the process called decay.

Parasites such as tapeworms and mosquitoes live on or in another living organism (called the host) from which they obtain food.
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Old Friday, April 11, 2008
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Arrow Everyday Science Notes

Computer:

Machine capable of executing instructions to perform operations on data. The distinguishing feature of a computer is its ability to store its own instructions. This ability makes it possible for a computer to perform many operations without the need for a person to enter new instructions each time. Modern computers are made of high-speed electronic components that enable the computer to perform thousands of operations each second.
Generations of computers are characterized by their technology. First-generation digital computers, developed mostly in the U.S. after World War II, used vacuum tubes and was enormous. The second generation, introduced c. 1960, used transistors and were the first successful commercial computers. Third-generation computers (late 1960s and 1970s) were characterized by miniaturization of components and use of integrated circuits. The microprocessor chip, introduced in 1974, defines fourth-generation computers.

Microprocessor:

A microprocessor is a computer processor on a microchip. It's sometimes called a logic chip. It is the "engine" that goes into motion when you turn your computer on. A microprocessor is designed to perform arithmetic and logic operations that make use of small number-holding areas called registers. Typical microprocessor operations include adding, subtracting, comparing two numbers, and fetching numbers from one area to another. These operations are the result of a set of instructions that are part of the microprocessor design. When the computer is turned on, the microprocessor is designed to get the first instruction from the basic input/output system (BIOS) that comes with the computer as part of its memory. After that, either the BIOS, or the operating system that BIOS loads into computer memory, or an application program is "driving" the microprocessor, giving it instructions to perform.

Digital Computers:

A digital computer is designed to process data in numerical form. Its circuits perform directly the mathematical operations of addition, subtraction, multiplication, and division. The numbers operated on by a digital computer are expressed in the binary system; binary digits, or bits, are 0 and 1, so that 0, 1, 10, 11, 100, 101, etc., correspond to 0, 1, 2, 3, 4, 5, etc. Binary digits are easily expressed in the computer circuitry by the presence (1) or absence (0) of a current or voltage. A series of eight consecutive bits is called a “byte”; the eight-bit byte permits 256 different “on-off” combinations. Each byte can thus represent one of up to 256 alphanumeric characters, and such an arrangement is called a “single-byte character set” (SBCS); the de facto standard for this representation is the extended ASCII character set. Some languages, such as Japanese, Chinese, and Korean, require more than 256 unique symbols. The use of two bytes, or 16 bits, for each symbol, however, permits the representation of up to 65,536 characters or ideographs. Such an arrangement is called a “double-byte character set” (DBCS); Unicode is the international standard for such a character set. One or more bytes, depending on the computer's architecture, is sometimes called a digital word; it may specify not only the magnitude of the number in question, but also its sign (positive or negative), and may also contain redundant bits that allow automatic detection, and in some cases correction, of certain errors. A digital computer can store the results of its calculations for later use, can compare results with other data, and on the basis of such comparisons can change the series of operations it performs. Digital computers are used for reservations systems, scientific investigation, data-processing and word-processing applications, desktop publishing, electronic games, and many other purposes.

Analog Computers:

Computer in which continuously variable physical quantities, such as electrical potential, fluid pressure, or mechanical motion, are used to represent (analogously) the quantities in the problem to be solved. The analog system is set up according to initial conditions and then allowed to change freely. Answers to the problem are obtained by measuring the variables in the analog model. Analog computers are especially well suited to simulating dynamic systems; such simulations may be conducted in real time or at greatly accelerated rates, allowing experimentation by performing many runs with different variables. They have been widely used in simulating the operation of aircraft, nuclear power plants, and industrial chemical processes.

Minicomputers:

A minicomputer, a term no longer much used, is a computer of a size intermediate between a microcomputer and a mainframe. Typically, minicomputers have been stand-alone computers (computer systems with attached terminals and other devices) sold to small and mid-size businesses for general business applications and to large enterprises for department-level operations. In general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously.

Microcomputers:

A digital computer whose central processing unit consists of a microprocessor, a single semiconductor integrated circuit chip. Once less powerful than larger computers, microcomputers are now as powerful as the minicomputers and super minicomputers of just several years ago. This is due in part to the growing processing power of each successive generation of microprocessor, plus the addition of mainframe computer features to the chip, such as floating-point mathematics, computation hardware, memory management, and multiprocessing support.

Microcomputers are the driving technology behind the growth of personal computers and workstations. The capabilities of today's microprocessors in combination with reduced power consumption have created a new category of microcomputers: hand-held devices. Some of these devices are actually general-purpose microcomputers: They have a liquid-crystal-display (LCD) screen and use an operating system that runs several general-purpose applications. Many others serve a fixed purpose, such as telephones that provide a display for receiving text-based pager messages and automobile navigation systems that use satellite-positioning signals to plot the vehicle's position.

Mainframe:

A mainframe (also known as "big iron") is a high-performance computer used for large-scale computing purposes that require greater availability and security than a smaller-scale machine can offer. Historically, mainframes have been associated with centralized rather than distributed computing, although that distinction is blurring as smaller computers become more powerful and mainframes become more multi-purpose.

A mainframe may support 100-500 users at one time. Typically, mainframes have a word length of 64 bits and are significantly faster and have greater capacity than the minicomputer and the microcomputer.

Supercomputers:

Supercomputer is a computer that performs at or near the currently highest operational rate for computers. A supercomputer is typically used for scientific and engineering applications that must handle very large databases or do a great amount of computation (or both). At any given time, there are usually a few well-publicized supercomputers that operate at the very latest and always incredible speeds. The term is also sometimes applied to far slower (but still impressively fast) computers. Most supercomputers are really multiple computers that perform parallel processing. In general, there are two parallel processing approaches: symmetric multiprocessing (SMP) and massively parallel processing (MPP).

Hardware:

Mechanical and electronic parts that constitute a computer system, as distinguished from the computer programs (Software) that drive the system. The main hardware elements are the Central Processing Unit, Disk or magnetic tape data storage devices, Cathode-Ray Tube display terminals, keyboards, and Printers. In operation, a computer is both hardware and software. One is useless without the other. The hardware design specifies the commands it can follow, and the software instructions tell it what to do.

Software:

A set of instructions that cause a computer to perform one or more tasks. The set of instructions is often called a program or, if the set is particularly large and complex, a system. Computers cannot do any useful work without instructions from software; thus a combination of software and hardware (the computer) is necessary to do any computerized work. A program must tell the computer each of a set of minuscule tasks to perform, in a framework of logic, such that the computer knows exactly what to do and when to do it.

Input Devices:

An input device is a hardware mechanism that transforms information in the external world for consumption by a computer. Often, input devices are under direct control by a human user, who uses them to communicate commands or other information to be processed by the computer, which may then transmit feedback to the user through an output device. Input and output devices together make up the hardware interface between a computer and the user or external world. Typical examples of input devices include keyboards and mice. However, there are others which provide many more degrees of freedom. In general, any sensor which monitors, scans for and accepts information from the external world can be considered an input device, whether or not the information is under the direct control of a user.

Keyboard:

In computing, a keyboard is a peripheral partially modeled after the typewriter keyboard. Keyboards are designed to input text and characters, as well as to operate a computer. Physically, keyboards are an arrangement of rectangular buttons, or "keys". Keyboards typically have characters engraved or printed on the keys; in most cases, each press of a key corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence; other keys do not produce any symbol, but instead affect the operation of the computer or the keyboard itself.
Roughly 50% of all keyboard keys produce letters, numbers or signs (characters). Other keys can produce actions when pressed, and other actions are available by the simultaneous pressing of more than one action key.

Mouse:

A device that controls the movement of the cursor or pointer on a display screen. A mouse is a small object you can roll along a hard, flat surface. Its name is derived from its shape, which looks a bit like a mouse, its connecting wire that one can imagine to be the mouse's tail, and the fact that one must make it scurry along a surface. As you move the mouse, the pointer on the display screen moves in the same direction. Mice contain at least one button and sometimes as many as three, which have different functions depending on what program is running.

Output Devices:

Any machine capable of representing information from a computer. This includes display screens, printers, plotters, and synthesizers.

Display Screen:

The monitor displays the video and graphics information generated by the computer through the video card. Monitors are very similar to televisions but display information at a much higher quality. The Monitor is also known as monitor. The term monitor, however, usually refers to the entire box, whereas display screen can mean just the screen.

Printer:

A printer outputs data that is seen on the computer screen. Most printers are used through a parallel port, but some newer ones use USB connections. USB is somewhat faster, but there's not much of a difference for printers. Networked computers usually print to a printer through the network card. The most crucial printer measurement is its dots per inch rating. Although this can be misleading, a higher number is generally better. Printers are best chosen by actually seeing the quality of the printer output.

Scanner:

A scanner is a piece of hardware used to scan a document, i.e., create a digital copy. Although flatbed scanners are the most common type and operate much like a photocopy machine, there are many types of scanners, including some that never touch the document itself. Scanners use a variety of connection formats including Parallel Port, USB, and SCSI. USB is simple, SCSI is fast, and Parallel Port is extremely slow.

CPU (Central Processing Unit)

Stands for "Central Processing Unit." This is the pretty much the brain of computer. It processes everything from basic instructions to complex functions. Any time something needs to be computed, it gets sent to the CPU.

Generally, the CPU is a single microchip, but that doesn't necessarily have to be the case. In the consumer desktop and laptop market, the CPU market is dominated by Intel, AMD, and IBM. These manufacturers supply the computer makers such as Dell, HP, and Apple.

Due to its importance to every computing task, the speed of the CPU, usually measured in gigahertz (GHz) is the number that most vendors use in their marketing campaigns. In the past, the larger the number, the faster the computer could be expected to be. However, in recent years, the speed of the CPU has had less impact as other components of a computer take on more and more of the workload. Also, differences in technology mean that a slower chip that performs more calculations per cycle can actually be faster than a higher rate chip doing fewer calculations per cycle.


Bit:

A binary digit. The term was first used in 1946 by John Tukey, a leading statistician and adviser to five presidents. In the computer, electronics, and communications fields, “bit” is generally understood as a shortened form of “binary digit.” In a numerical binary system, a bit is either a 0 or 1. Bits are generally used to indicate situations that can take one of two values or one of two states, for example, on and off, true or false, or yes or no. If, by convention, 1 represents a particular state, then 0 represents the other state. For example, if 1 stands for “yes,” then 0 stands for “no.” A bit is abbreviated with a small "b".

Byte:

The common unit of computer storage from desktop computer to mainframe. The term byte was coined by Dr. Werner Buchholz in July 1956, during the early design phase for the IBM Stretch computer. It is made up of eight binary digits (bits). A ninth bit may be used in the memory circuits as a parity bit for error checking. The term was originally coined to mean the smallest addressable group of bits in a computer, which has not always been eight. A byte is abbreviated with a "B".

RAM:

RAM stands for Random Access Memory. Computer main memory in which specific contents can be accessed (read or written) directly by the CPU in a very short time regardless of the sequence (and hence location) in which they were recorded. Two types of memory are possible with random-access circuits, static RAM (SRAM) and dynamic RAM (DRAM). A single memory chip is made up of several million memory cells. In a SRAM chip, each memory cell stores a binary digit (1 or 0) for as long as power is supplied. In a DRAM chip, the charge on individual memory cells must be refreshed periodically in order to retain data. Because it has fewer components, DRAM requires less chip area than SRAM; hence a DRAM chip can hold more memory, though its access time is slower. The size of the RAM (measured by kilobytes) is an important indicator of the capacity of the computer.

ROM:

ROM stands for Read Only Memory. A memory chip that permanently stores instructions and data. Also known as "mask ROM," its content is created in the last masking stage of the chip manufacturing process, and it cannot be changed. Once data has been written onto a ROM chip, it cannot be removed and can only be read.
Unlike main memory (RAM), ROM retains its contents even when the computer is turned off. ROM is referred to as being nonvolatile, whereas RAM is volatile.

Computer Networking:

A computer network is an interconnected group of computers. Networks may be classified by the network layer at which they operate according to basic reference models considered as standards in the industry, such as the four-layer Internet Protocol Suite model. While the seven-layer Open Systems Interconnection (OSI) reference model is better known in academia, the majority of networks use the Internet Protocol Suite (IP).
Computer networks may be classified according to the scale.

Personal area network(PAN)

A personal area network (PAN) is the interconnection of information technology devices within the range of an individual person, typically within a range of 10 meters. For example, a person traveling with a laptop, a personal digital assistant (PDA), and a portable printer could interconnect them without having to plug anything in, using some form of wireless technology. Typically, this kind of personal area network could also be interconnected without wires to the Internet or other networks.

Local Area Network (LAN)

Communications network connecting computers by wire, cable, or fiber optics link. Usually serves parts of an organization located close to one another, generally in the same building or within 2 miles of one another. Allows users to share software, hardware and data. The first LAN put into service occurred in 1964 at the Livermore Laboratory to support atomic weapons research. LANs spread to the public sector in the late 1970s and were used to create high-speed links between several large central computers at one site.
Initially, LANs were limited to a range of 185 meters or 600 feet and could not include more than 30 computers. Today, a LAN could connect a max of 1024 computers at a max distance of 900 meters or 2700 feet.

Campus Area Network(CAN)

A campus area network (CAN) is a computer network interconnecting a few local area networks (LANs) within a university campus or corporate campus. Campus area network may link a variety of campus buildings including departments, the university library and student halls of residence. A campus area network is larger than a local area network but smaller than a metropolitan area network (MAN) or wide area network (WAN). CAN can also stand for corporate area network.

Metropolitan area network (MAN)

A metropolitan area network (MAN) is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.

MAN networks use a different standard for communications; 802.6 as assigned by the Institute of Electrical and Electronics Engineers (IEEE), which uses a different bus technology to transmit and receive data than most larger or smaller networks. This allows MAN networks to operate more efficiently than they might if they were simply LAN networks linked together.

Wide area network (WAN)

The wide area network, often referred to as a WAN, is a communications network that makes use of existing technology to connect local computer networks into a larger working network that may cover both national and international locations. This is in contrast to both the local area network and the metropolitan area network, which provides communication within a restricted geographic area. The largest WAN in existence is the Internet.

Arithmetic Logic Unit(ALU)

In computing, an arithmetic logic unit (ALU) is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers. The processors found inside modern CPUs and GPU have inside them very powerful and very complex ALU; a single component may contain a number of ALU.

Mathematician John von Neumann proposed the ALU concept in 1945, when he wrote a report on the foundations for a new computer called the EDVAC.

Control Unit:

The control unit is the circuitry that controls the flow of information through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC.

The functions performed by the control unit vary greatly by the internal architecture of the CPU, since the control unit really implements this architecture. On a regular processor that executes x86 instructions natively, the control unit performs the tasks of fetching, decoding, managing execution and then storing results. On a processor with a RISC core the control unit has significantly more work to do. It manages the translation of x86 instructions to RISC micro-instructions, manages scheduling the micro-instructions between the various execution units, and juggles the output from these units to make sure they end up where they are supposed to go. On one of these processors the control unit may be broken into other units (such as a scheduling unit to handle scheduling and a retirement unit to deal with results coming from the pipeline) due to the complexity of the job it must perform.

Modem:

Equipment that converts digital signals into analog signals for purpose of transmission over a telephone line. Signal is then converted back to digital form so that it can be processed by a receiving computer. Modems are typically used to link computers via telephone lines. Short for modulator-demodulator.
The speed at which a modem transmits data is measured in units called bits per second or bps. The first modems ran at even less than 300 bps. Now 1200, 2400, and 9600 bps modems are considered slow. The faster models reach speeds of 14,400 and 28,800 bps. The faster the modem, the faster the data (for example, images from the Web) appear. Even a 28,800 bps modem, however, cannot compare to the several million bps speed that a campus Ethernet connection gives you.

Register:

A small, high-speed computer circuit that holds values of internal operations, such as the address of the instruction being executed and the data being processed. When a program is debugged, register contents may be analyzed to determine the computer's status at the time of failure.
In microcomputer assembly language programming, programmers look at the contents of registers routinely. Assembly languages in larger computers are often at a higher level.

Cache Memory:

Cache memory is extremely fast memory that is built into a computer’s central processing unit (CPU), or located next to it on a separate chip. The CPU uses cache memory to store instructions that are repeatedly required to run programs, improving overall system speed. The advantage of cache memory is that the CPU does not have to use the motherboard’s system bus for data transfer. Whenever data must be passed through the system bus, the data transfer speed slows to the motherboard’s capability. The CPU can process data much faster by avoiding the bottleneck created by the system bus.

Cache that is built into the CPU is faster than separate cache, running at the speed of the microprocessor itself. However, separate cache is still roughly twice as fast as Random Access Memory (RAM). Cache is more expensive than RAM, but it is well worth getting a CPU and motherboard with built-in cache in order to maximize system performance.

Computer Virus:

A virus is a program designed to infect and potentially damage files on a computer that receives it. The code for a virus is hidden within an existing program—such as a word processing or spreadsheet program—and when that program is launched, the virus inserts copies of itself into other programs on the system to infect them as well. Because of this ability to reproduce itself, a virus can quickly spread to other programs, including the computer's operating system. A virus may be resident on a system for a period of time before taking any action detectable to the user. The impact of other viruses may be felt immediately. Some viruses causes little or no damage. For example, a virus may manifest itself as nothing more than a message that appears on the screen at certain intervals. Other viruses are much more destructive and can result in lost or corrupted files and data. At their worst, viruses may render a computer unusable, necessitating the reinstallation of the operating system and applications.
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You should have all the recommended books of the syllabus. These notes are also helpful and u can get notes on any topic if not available in the books.
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Post Is Nuclear Power The Solution For Global Warming?

Is Nuclear Power The Solution For Global Warming?


Nuclear power is not a solution for Global Warming. It is neither the only option, nor the best one.

First of all, let us discuss the meaning of global warming and its consequences to the environment. Global warming is the increase of temperature in the Earth due to the use of fuels fossils and other industrial level processes, that form an accumulation in the atmosphere of gases which provide the Greenhouse Effect, such as Carbon Dioxide, Methanol, Nitrogen Oxide and the CFCs.

It’s known that Carbon Dioxide can retain the infrared radiation of the Sun on atmosphere, stabilizing then the temperature through the Greenhouse Effect. Therefore, it can also cause our death, as we are increasing its quantity in the air, which makes the Earth really hot, causing the high ocean level(melting the ices in the Poles), killing people that live in countries not used to cold weather. Also, a problem that is clear for everyone is the change in the seasons, which are getting unstable, with hot winters, cold summers and affecting some animals’ hibernation.

The Problems of Global Warming are gerenally caused by the bad use of energy, the fuels(cars and traffic) and pollution. A Solution for the Global Warming then comes, by the government’s eyes(it doesn’t mean it is right), and it is: Nuclear Power.

Nuclear Power is the energy that the atom has, keeping protons and neutrons together. If for exemple, a neutron reaches the nucleus of an atom of Uraniun-235, dividing it with emission from 2 to 3 neutrons, part of the energy that links the protons and the neutrons goes out in form of heat. This process is called nuclear fission. The Nuclear Power is an option of energy source: it’s possible to use the heat emmited from the fission to move the water, which moves the turbines which generates the eletricity.
In a reactor of power type PWR the fuel is uranium enriched 3.5%. Uranium found in the environment contains just 0.7% of the isotopus 235U, then it must be processed until the proportion gets 3.5%.

FIGURE 1 – The Project of a water reactor[7]

The complete process of attainment of the nuclear fuel is known as cycle of the fuel and it has diverse stages:

i) extration of the ore from the ground;

ii) improvement to separate the Uraniun from other ores;

iii) conversion in gas of the product of the improvement, called yellow cake

iv) enrichment of the gas, in which the ratio of 235U is increased until the desired level;

v) reconversion of the enriched gas of Uraniun for the dust state;

vi) manufacture of tablets from the compacting of the dust;

vii) and finally the assembly of the combustible elements, when they place the tablets in metallic cylinders that will go to form the combustible elements of the nucleus of the reactor.

Currently, in the world, there are, in operation, 440 nuclear reactors directed toward the generation of energy in 31 countries. Other 33 are in construction. About 17% of the world-wide’s electric generation is of nuclear origin, the same ratio of the use of hidroeletric energy and energy produced by gas.

Some developed countries have its supplying of electric energy with one high percentage of nuclear generation. Between them, France has 78%, Belgium 57%, Japan 39%, the South Korea 39%, Germany 30%, Sweden 46%, Switzerland 40%. Only in the United States, the 104 reactors in operation, that generate 20% of the electricity of that country, produce more electricity than all the Brazilian system of electric generation. Beyond these reactors, 284 reactors of research in 56 countries function more, without counting to an esteem number of 220 reactors of propulsion in ships and submarines.

If it is so complicated preparing the nuclear power, why should we be for it? That is what the gorvenment guide us to, hidding what? The problems. Energy resources are two: the reuseable ones, and the non-reuseable ones. Not very happy to say that Nuclear Power is not reuseable. And what do they do about the waste? In some places, like in Finland, there are people, like Posiva, who know how to get those things in a right place: The spent fuel is set in cast iron, which is then encased in copper and dropped down a borehole. The borehole is filled with saturated bentonite, a kind of clay. He also affirms that: “Posiva's metallurgists suggest that under these conditions the copper barrier would be good for at least a million years.” Though, George Monbiot stated that not all the countries can do what Finland does and it may no longer be available as a solution.

The whole world is not so ignorant about this, and some argumentations are already made about this theme. Some people, like James Lovelock, afirm that the only solution for Global warming is Nuclear energy, giving arguments such as explaining how the world is in danger, as said before, by high temperatures all around the world and, he comfirmed "only one immediately available source does not cause global warming and that is nuclear energy" as it does not emmit gases from the Greehouse Effect. However, some people have argumented against these afirmations, such as George Monbiot, who has replied to Lovelock, saying that “he was wrong on two counts. It is not the only one, and it is not immediately available”, stating the dangers of Nuclear Energy into human being and nature, as well as he states that the use of nuclear energy is not immediately avaiable because the governmet is not up to pay for suddenly, and something like a nuclear plant takes a long time to be done. Monbiot also afirms that “

The Rocky Mountain Institute has shown that you can save seven times as much carbon through electricity efficiencies as you can by investing in nuclear. And you kill no one.” As an add to the side against using nuclear power, two dutch researchers - Jan Willem Storm van Leeuwen and Philip Smith - show that, ahead the increasing exploration of Uranium, the extration is going to become more and more difficult and expensive, spending increasing amounts of energy, which is going to launch in the atmosphere a great volume of carbon dioxide.

Though, a lot of argument are in fight to decide if it’s useful or not using nuclear power. The reason the people are talking about this, is all because of global warming, using it as an alternative source, however what about the environmental impacts? There are three main environmental problems of this energy source. The first one is the manipulation of radioactive material in the process of nuclear fuel production and in the nuclear reactors, with risks of emptyings and accidents. The second problem is related to the clandestine shunting line possibility of nuclear material for use in weapons, for example, increasing risks of nuclear proliferation. The last one is the one mentioned above: the uraniun waste.

The alternative sources as solar, aeolian and biomass, are not totally exempt of ambient impacts, even though they can be relatively less aggressive to the environment. The use in wide scale of panels or biomass implies in an alteration in the use of the ground. The manufacture of components of these technologies also produces ambient problems, as it is the case of the extration of silicon for panels. Many of these systems depend on chemical batteries for storage of the electricity, that still present serious problems of contamination for toxic lead and other metals for the environment.

The use of nuclear power, then, is a kind of solution, but not he best because of its environmental problems, difficulty to extract, and, at last, the energy sources are just 20% guilty of the global warming. If the people are looking for best solutions, they should start with something easier, like protecting their own houses, using less energy, less polution, less use of cars, preservation of trees and recycling. Why should we keep looking for such expensive solutions, while we can just use our conscience and do simple solution, which are basically, the best ones.
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Post Global Warming

GLOBAL WARMING


ABSTRACT: The term "global warming" is a specific example of climate change, which can also refer to global cooling. In common usage, the term refers to recent warming and implies a human influence. The United Nations Framework Convention on Climate Change (UNFCCC) uses the term "climate change" for human-caused change, and "climate variability" for other changes.The Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations” via the greenhouse effect. Natural phenomena such as solar anthropogenic Natural phenomena climate change climate variability greenhouse gas solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950. Climate model projections summarized by the IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century. The range of values results from the use of differing scenarios of future greenhouse gas emissions as well as models with differing climate sensitivity.

KEYWORDS: Global cooling, Greenhouse gas, Solar variation, Anthropogenic, Natural phenomena, Climate variability.

WHAT IS GLOBAL WARMING ?: Global warming is the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation. The global average air temperature near the Earth's surface rose 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the hundred years ending in 2005. Although most studies focus on the period up to 2100, warming and sea level rise are expected to continue for more than a thousand years even if greenhouse gas levels are stabilized. The delay in reaching equilibrium is a result of the large heat capacity of the oceans. Increasing global temperature will cause sea level to rise, and is expected to increase the intensity of extreme weather events and to change the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, trade routes, glacier retreat, species extinctions and increases in the ranges of disease vectors.

CAUSES OF GLOBAL WARMING: The Earth's climate changes in response to external forcing, including variations in its orbit around the Sun (orbital forcing), volcanic eruptions, and atmospheric greenhouse gas concentrations. The detailed causes of the recent warming remain an active field of research, but the scientific consensus is that the increase in atmospheric greenhouse gases due to human activity caused most of the warming observed since the start of the industrial era. Some other hypotheses departing from the consensus view have been suggested to explain the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity

* Greenhouse Gasses In Atmosphere : The greenhouse effect was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warm a planet's lower atmosphere and surface. Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F), without which Earth would be uninhabitable. Rather, the issue is how the strength of the greenhouse effect changes when human activity increases the atmospheric concentrations of some greenhouse gases.
On Earth, the major greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect (not including clouds); carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone, which causes 3–7%. Molecule for molecule, methane is a more effective greenhouse gas than carbon dioxide, but its concentration is much smaller so that its total radiative forcing is only about a fourth of that from carbon dioxide. Some other naturally occurring gases contribute very small fractions of the greenhouse effect; one of these, nitrous oxide (N2O), is increasing in concentration owing to human activity such as agriculture. The atmospheric concentrations of CO2 and CH4 have increased by 31% and 149% respectively since the beginning of the industrial revolution in the mid-1700s. The IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100.Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100, if coal, tar sands or methane clathrates are extensively used.

* Solar Variation : A few papers suggest that the Sun's contribution may have been underestimated. Two researchers at Duke University, Bruce West and Nicola Scafetta, have estimated that the Sun may have contributed about 45–50% of the increase in the average global surface temperature over the period 1900–2000, and about 25–35% between 1980 and 2000.[38] A paper by Peter Stott and other researchers suggests that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated.[39] They nevertheless conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming since the mid-20th century is likely attributable to the increases in greenhouse gases.
A different hypothesis is that variations in solar output, possibly amplified by cloud seeding via galactic cosmic rays, may have contributed to recent warming.[40] It suggests magnetic activity of the sun is a crucial factor which deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.[41]One predicted effect of an increase in solar activity would be a warming of most of the stratosphere, whereas greenhouse gas theory predicts cooling there [42].

The observed trend since at least 1960 has been a cooling of the lower stratosphere [43]. Reduction of stratospheric ozone also has a cooling influence, but substantial ozone depletion did not occur until the late 1970s.[44] Solar variation combined with changes in volcanic activity probably did have a warming effect from pre-industrial times to 1950, but a cooling effect since.[1] In 2006, Peter Foukal and other researchers from the United States, Germany, and Switzerland found no net increase of solar brightness over the last thousand years. Solar cycles led to a small increase of 0.07% in brightness over the last thirty years. This effect is far too small to contribute significantly to global warming

* Climate Variability : In recent usage, especially in the context of environmental policy, the term "climate change" often refers to changes in modern climate.Climate change is the variation in the Earth's global climate or in regional climates over time. It involves changes in the variability or average state of the atmosphere over durations ranging from decades to millions of years. These changes can be caused by dynamic process on Earth, external forces including variations in sunlight intensity, and more recently by human activities.

Climate changes can include changes in the average temperature, amount of precipitation, days of sunlight, and other variables that might be measured at any given site. However, there are also changes within the Earth's environment that can affect the climate such as Glaciations. Glaciers are recognized as being among the most sensitive indicators of climate change, advancing substantially during climate cooling (e.g., the Little Ice Age) and retreating during climate warming on moderate time scales. Glaciers grow and collapse, both contributing to natural variability and greatly amplifying externally forced changes. For the last century, however, glaciers have been unable to regenerate enough ice during the winters to make up for the ice lost during the summer months.

* Anthropogenic : Anthropogenic effects, processes, objects, or materials are those that are derived from human activities, as opposed to those occurring in natural environments without human influences. Anthropogenic literally means "producing man". The correct term for "produced by man" would be anthropogenous.

Anthropogenic sources include industry, agriculture, mining, transportation, construction, habitations and deforestation.

Industry: Release of gases and dust into the atmosphere.
Waste disposal practices.
Air pollution, water pollution

Agriculture: Diversion of surface and groundwater.
Ground water Stalinization due to inadequate drainage.
Pollution of soil and water by chemicals found in fertilizer

Mining: Removal of topsoil and creation of spoil piles.
Diversion of groundwater by mine shafts.
Surface runoff bearing mining wastes.
Release of air pollution by refining processes.

Transportation: Diversion of surface water flow by roadways.
Vehicular air pollution.
Roadway noise, aircraft noise and transit noise.

Construction: Removal of natural habitats by grading and building
Diversion of groundwater.
Filling in marshes, bay lands, swamps, ponds, stream beds.


Habitations: Concentration of human activities in discrete zones.
Concentration of waste products, sewage, and debris

EFFECT OF GLOBAL WARMING : The predicted effects of global warming on the environment and for human life are numerous and varied. It is generally difficult to attribute specific natural phenomena to long-term causes, but some effects of recent climate change may already be occurring. Rising sea levels, glacier retreat, Arctic shrinkage, and altered patterns of agriculture are cited as direct consequences, but predictions for secondary and regional effects include extreme weather events, an expansion of tropical diseases, changes in the timing of seasonal patterns in ecosystems, and drastic economic impact. Concerns have led to political activism advocating proposals to mitigate, eliminate, or adapt to it. The 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) includes a summary of the expected effects. Most of the consequences of global warming would result from one of three physical changes: sea level rise, higher local temperatures, and changes in rainfall patterns. Sea level is generally expected to rise 18 to 59 cm (7.1 to 23.2 inches) by the end of the century.

EFFECT ON WEATHER

* Extreme Weather : Storm strength leading to extreme weather is increasing, such as the power dissipation index of hurricane intensity. Kerry Emanuel writes that hurricane power dissipation is highly correlated with temperature, reflecting global warming. Hurricane modeling has produced similar results, finding that hurricanes, simulated under warmer, high-CO2 conditions, are more intense; there is less confidence in projections of a global decrease in numbers of hurricane. substantially higher risk of extreme weather does not necessarily mean a noticeably greater risk of slightly-above-average weather.However, the evidence is clear that severe weather and moderate rainfall are also increasing. Increases in temperature are expected to produce more intense convection over land and a higher frequency of the most severe storms

* Increased Evaporation : As the climate grows warmer and the causes of global dimming are reduced, evaporation will increase due to warmer oceans. Because the world is a closed system this will cause heavier rainfall, with more erosion. This erosion, in turn, can in vulnerable tropical areas (especially in Africa) lead to desertification due to deforestation. On the other hand, in other areas, increased rainfall lead to growth of forests in dry desert areas. The IPCC Third Annual Report says: "...global average water vapor concentration and precipitation are projected to increase during the 21st century

* Glacier Retreat And Disappearance : In historic times, glaciers grew during a cool period from about 1550 to 1850 known as the Little Ice Age.

The loss of glaciers not only directly causes landslides, flash floods and glacial lake overflow[36], but also increases annual variation in water flows in rivers. Glacier runoff declines in the summer as glaciers decrease in size, this decline is already observable in several regions [37]. Glaciers retain water on mountains in high precipitation years, since the snow cover accumulating on glaciers protects the ice from melting. In warmer and drier years, glaciers offset the lower precipitation amounts with a higher meltwater input [35].

* Sea Level Rise : With increasing average global temperature, the water in the oceans expands in volume, and additional water enters them which had previously been locked up on land in glaciers, "The IPCC predicts that sea levels could rise by as much as 59 cm this century. [50] Hansen’s paper argues that the slow melting of ice sheets the panel expects doesn’t fit the data. The geological record suggests that ice at the poles does not melt in a gradual and linear fashion, but flips suddenly from one state to another. When temperatures increased to 2-3 degrees above today’s level 3.5 million years ago, sea levels rose not by 59 centimeters but by 25 meters. The ice responded immediately to changes in temperature.

* Acidification : The world’s oceans soak up much of the carbon dioxide produced by living organisms, either as dissolved gas, or in the skeletons of tiny marine creatures that fall to the bottom to become chalk or limestone. Oceans currently absorb about one tone of CO2 per person per year. It is estimated that the oceans have absorbed around half of all CO2 generated by human activities since 1800.But in water, carbon dioxide becomes a weak carbonic acid, and the increase in the greenhouse gas since the industrial revolution has already lowered the average pH.

* Effects Of Agriculture : For some time it was hoped that a positive effect of global warming would be increased agricultural yields, because of the role of carbon dioxide in photosynthesis, especially in preventing photorespiration, which is responsible for significant destruction of several crops. In Iceland, rising temperatures have made possible the widespread sowing of barley, which was untenable twenty years ago. Some of the warming is due to a local (possibly temporary) effect via ocean currents from the Caribbean, which has also affected fish stocks.

* Spread Of Diseases : Global warming is expected to extend the favorable zones for vectors conveying infectious disease such as dengue fever[139] and malaria[140][141] In poorer countries, this may simply lead to higher incidence of such diseases. In richer countries, where such diseases have been eliminated or kept in check by vaccination, draining swamps and using pesticides, the consequences may be felt more in economic than health terms. The World Health Organization (WHO) says global warming could lead to a major increase in insect-borne diseases in Britain and Europe, as northern Europe becomes warmer, ticks - which carry encephalitis and lyme disease - and sandflies - which carry visceral leishmaniasis - are likely to move in.
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are these notes enough for css papers?
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No these notes are not enough for EDSpaper? It lacks many things such as Muslim scientists,Scietific reasons etc
one must cover following areas for Evereyday science.
1] Muslim scientists
2]Short notes such as Fertilizers,Laser, Earth.Atmosphere,Pesticides,Balance diet,solar system,Vitamins
3] Scientific reasons
4] Definations Isotopes,Radioactivity,enzymes,Pllen grains etc
5]Abbreviations and Acronms
6]Units and Instruments
7] For Long questios Energy and its forms,Soil erosion, water logging, Nitrogen cycle etc
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there are some braches of science that are not in discuss. please also post the branches of science
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Branches of biology
1] Botany: study of plants.
2] Zoology; study of animals.
3] Microbiology: study of micro organisms like bacteria etc
4] Cytology: study of structure and functions of cells.
5] Physiology: study of different parts of body.
6] Ecology: study of relationship between organisms and environment.
7] Taxonomy: study of classification and naming of organisims.
8] Genetics: study of inherited charactrs from parents to offspring.
9] Palentology: study of fossils.
10] Biotechnology: study of use of living organisms for the welfareof mankind.
11] Entomology:study of insects.
12] Ornithology: Study of birds.
13] Mammology: study of mammals.
14] Odontology: study of teeth.
15] Mycology: study of fungi..
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i find 103 branches of science. in the book of Eeryday Science.
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