Mitosis

Mitosis

Mitosis is a type of cell division involves a series of complex changes in both, the nucleus and cytoplasm. During mitosis the diploid (2n) number of chromosomes kept constant in daughter cells.

Interphase

It is an active phase of cell division which occurs before the onset of mitosis. The basic components of cell duplicated during this phase particularly the DNA and histones. Moreover various proteins are also synthesized during interphase, which are essential for proper completion of mitosis.

Main Phases of Mitosis

The process of mitosis has been studied in both plants and animals. Walther studies it in animals wile Strassburger studied it in plants. According to these studies, mitosis takes place in somatic cells and comprises two phases.

1- Cytokinesis (division of cytoplasm)
2- Karyokinesis (division of nucleus)

Cytokinesis

Cytokinesis refers to the division of cytoplasm. In animals, it is carried out by the formation of cell membrane and contraction of cytoplasm. Cell membrane moves inward deeply and divides the cell into two halves. In plants, some special structures are formed by the transformation of spindle fibers at equatorial; these structures are called phragmoplast which leads to the division of one cell into two.

Karyokinesis

Karyokinesis refers to the division of nucleus. It comprises four stages:

1- Prophase
2- Metaphase
3- Anaphase
4- Telophase

1- Prophase

It involves the appearance of chromosomes as thin threads by the condensation of chromatin fiber in the nucleus. Each chromosome comprises two chromatids with centromere present in between. As mitosis proceeds, nucleolus and nuclear membrane also disappears gradually

2- Metaphase

During this phase spindle fibers starts to appear. Chromosomes get attached with spindle fibers and migrates from equator to opposites poles to take the final shape.

3- Anaphase

During anaphase, Spindle fibers attached to centromere pull them and two chromatids get separated from each other and move towards opposite poles.

4- Telophase

This phase is an opposite or reversal phase of prophase. All changes took place during prophase reverse to their original states. On reaching the poles, chromosome start uncoiling and nucleoli and nuclear membrane begins to appear, which results in the formation of two daughter cells.

Significance of Mitosis

Mitosis is a significant cell division which ensures the provision of correct and complete genetic information to the daughter cells. As chromosome have heredity material and number of chromosomes must be kept constant in daughter cells in order to transfer complete genetic information and mitosis keeps this number of chromosome constant. In case of abnormal number of chromosome, several physiological and psychological disorders can cause in an organism. So we can say that the product of mitosis is not only quantitative but qualitative as well. Healing of wounds and formation of new cells takes place due to the process of mitosis.

Nucleic Acid

Nucleic Acid

A nucleic acid is a macromolecule composed of polynucleotide chains. These polynucleotide chains are made up of several monomers which are called nucleotides. These nucleotides carry genetic information or form structures within cells. Ncleic acids are found in every living organism including viruses as well. Nucleic acids were first discovered in 1871 by Friedrich Miescher.

Composition of Nucleic Acid

Each nucleotide comprises three components; Pentose Sugar, Phosphase Group and nitrogenous bases. Nitrogenous bases are of two types; purine and pyrimidine. Purines are based on Adenine (A) and Guanine (G) while Pyrimidine are based on Cytosine (C), Thymine (T) and Uracil (U). Nitrogenous bases found in the two nucleic acid types are different: adenini, cytosine and guanine found in both RNA and DNA, while thymine only occurs in DNA and uracil only occurs in RNA. Some other types of nucleic acid also occur, for example inosine found in strands of mature tRNA.

Pentose Sugar in ribonucleotide is ribose and in deoxyribonucloetides is deoxyribose. Phosphate linkage with pentose sugar is called Phosphodiester Linkage. Phosphoric acid has ability to develop ester linkage with hydro oxyle(OH) groups of pentose sugar.

Types of Nucleic Acid

There are two types of nucleic acids.

1- RNA
2- DNA

1- RNA

RNA stands for Ribonucleic acid, is a single polynucleotide chain comprising nucleotide monomers. These monomers plays significant role during transcription. It transcribed genetic information from deoxyribonucleic acid (DNA) into proteins during protein synthesis. In this way RNA acts as a messenger between DNA and ribosomes which are protein synthesis complexes present in cell. RNA forms vital portions of ribosomes and serves as an essential carrier of amino acids during protein synthesis. RNA exists in three types which include:

1- tRNA (transfer RNA)
2- mRNA (messenger RNA)
3- rRNA (ribosomal RNA)

2- DNA

DNA stands for Deoxyribonucleic acid, comprises two polynucleotide chains linked together by weak hydrogen bonds. There are two hydrogen bonds between A and T and three hydrogen bonds between C and G. DNA is heredity material contain genetic information passed from generation to generation. Evidence from the study of bacterium (Pneumococcus) that DNA is heredity material. This genetic information plays essential role in the development and functioning of all known living organisms.

The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes or are involved in regulating the use of this genetic information. The amount of DNA depends upon the number of chromosomes present.

DNA comprises four types of nitrogenous bases i-e cytosine, thymine, guanine and adenine. These bases are linked together to form a polynucleotide chain. Two polynucleotide chains coil around each other to form the double helical sucture of DNA molecule.

What are Chromosomes?

Chromosomes

Chromosomes are important part of a cell discovered in 1876 by Waldeyer. In 1908 W.S. Sutton observed that genes are located on chromosomes and genetic phenomenon can be explained in terms of chromosomal behavior during cell division particularly during metaphase and anaphase.

Structure of Chromosome

Chromosome comprises two chromatids attached to centromere. Centromere is the point where spindle fibers get attached with them. The position is very important to distinguish the type of chromosome. You can say that on the basis of its position the type and shape of a chromosome can be defined.

Types of Chromosomes

On the basis of centromere’s position, chromosomes can be divided into four types.

1- Telocentric (Centromere present at one end of chromosome)
2- Acrocentric (Centromere present close to one end, so acrocentric chromosomes have very small arms)
3- Metacentric (Centromere present in centre with equal arms)
4- Submetacentric (Centromere present near the centre but not exactly in the centre therefore have an equal arms)

Karytype

It is the term used to describe the total chromosome complement of cell. Study of karytype helps in determining the total number of chromosome present in human beings and in other species.

Chemical Composition of Chromosomes

Chromosomes are chemically composed of DNA and basic protein. These basic proteins are called Histones. DNA and Histones combine together to form a structure which is called Nucleosome. Nucleosome comprises eight molecules of various types of histones with two turns of DNA molecules. Under electron microscope nucleosome appears as a beaded structure of 10nm diameter.

What is Ceramic?

Definition of Ceramic

A ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous (a glass).

Explanation of Ceramics

The word ceramic comes from the Greek word κεραμικός (keramikos) meaning pottery, which is said to derive from the Indo-European word ker, meaning heat. Ceramic may be used as an adjective describing a material, product or process; or as a singular noun, or, more commonly, as a plural noun, ceramics.

The earliest ceramics were pottery objects made from clay, later it has been used for manufacturing domestic, industrial and building products and art objects as well. In the 20th century, new ceramic materials were developed for use in advanced ceramic engineering e.g. in semiconductors.

Types of Ceramic Products

Ceramic products are divided into four categories including:

Structural Ceramic including bricks, pipes, floor and roof tiles.

Refractories including kiln linings, gas fire radiants, steel and glass making crucibles.

Whitewares Ceramic including tableware, wall tiles, pottery products, and sanitary ware

Technical Ceramic is also known as Engineering, Advanced, Special, and in Japan, Fine Ceramics. Such items include tiles used in the Space Shuttle Program, gas burner nozzles, ballistic protection, nuclear fuel uranium oxide pellets, bio-medical implants, jet engine turbine blades, and missile nose cones. Frequently the raw materials do not include clays.

Technical ceramics are further classified into three distinct material categories:

1- Oxides: Alumina, Zirconia.
2- Non-oxides: Carbides, Borides, Nitrides, Silicides.
3- Composites: Particulate reinforced combinations of oxides and non-oxides.

Each one of these classes can develop unique material properties.

Types of Ceramic Material

A ceramic material is often understood as restricted to inorganic crystalline oxide material. It is solid and inert. Ceramic materials are brittle, hard and strong in compression, weak in shearing and tension. They withstand chemical erosion that occurs in other materials subjected to acidic or caustic environment. Ceramics generally can withstand very high temperatures such as temperatures that range from 1,000 °C to 1,600 °C (1,800 °F to 3,000 °F). Exceptions include inorganic materials that do not include oxygen such as silicon carbide or silicone nitride.

A glass is often not understood as a ceramic because of its amorphous (non-crystalline) character. However, glass making involves several steps of the ceramic process and its mechanical properties are similar to ceramic materials.

Traditional ceramic raw materials include clay minerals such as kaolinite, whereas more recent materials include aluminium oxide, more commonly known as alumina. The modern ceramic materials, which are classified as advanced ceramics, include silicon carbide and tungsten carbide. Both are valued for their abrasion resistance, and hence find use in applications such as the wear plates of crushing equipment in mining operations. Advanced ceramics are also used in the medicine, electrical and electronics industries.

Crystalline Ceramics

Crystalline ceramic materials are not amenable to a great range of processing. Methods for dealing with crystalline ceramics tend to fall into one of two categories including making the ceramic in the desired shape, by reaction in situ and by "forming" powders into the desired shape, and then sintering to form a solid body.

Ceramic forming technique include shaping by hand (including a rotation process called "throwing"), Slip casting, tape casting (for making thin ceramic capacitors), injection moulding, dry pressing, and other variations.

Non-Crystalline Ceramics

Non-crystalline ceramics, being glasses, tend to be formed from melts. The glass is shaped when either fully molten, by casting, or when in a state of toffee-like viscosity, by methods such as blowing to a mold. If later heat-treatments cause this glass to become partly crystalline, the resulting material is known as a glass-ceramic.

What is Acid Rain?

Definition of Acid Rain

Acid rain describes any form of precipitation with high levels of nitric and sulfuric acids. It can occur in the form of fog, snow and tiny bits of dry material that settle to Earth.

Rotting vegetation and erupting volcanoes release some chemicals that can cause acid rain, but the main factor behind acid rain is human activities including burning of fossil fuels by coal-burning power plants, factories, and automobiles. By burning fossil fuels, sulfur dioxide (SO2) and nitrogen oxides (NO2) are released into the atmosphere. These gases react with water, oxygen, and other substances to form sulfuric and nitric acid. When acid rain reaches Earth, it flows across the surface in runoff water, enters water channels and absorbs into the soil.

Wet Deposition

Wet deposition of acids occurs when any form of precipitation (rain, snow) removes acids from the atmosphere and delivers it to the Earth's surface. This can result from the deposition of acids produced in the raindrops or by the precipitation removing the acids either in clouds or below clouds. Wet removal of both gases and aerosols are both of importance for wet deposition.

Dry Deposition

Acid deposition also occurs via dry deposition in the absence of precipitation. This can be responsible for 20% to 60% of total acid deposition. This occurs when particles and gases stick to the ground, plants or other surfaces.

Ecological Effects of Acid Rain

Acid rain has been proved to have adverse impacts on waters, aquatic life, soils, forests, buildings and human health.

Effect of Acid Rain on Water and Aquatic Life

Acid rain makes waters acidic and causes them to absorb the aluminum that makes its way from soil into lakes and streams. This combination makes waters toxic to crayfish, clams, fish, and other aquatic animals. Some species can tolerate acidic waters better than others. However, in an interconnected ecosystem, what impacts some species eventually impacts many more throughout the food chain—including non-aquatic species such as birds.

Both the lower pH and higher aluminum concentrations in surface water that occur as a result of acid rain can cause damage to fish and other aquatic animals. At pHs lower than 5 most fish eggs will not hatch and lower pHs can kill adult fish. As lakes and rivers become more acidic biodiversity is reduced. The United States Environmental Protection Agency's (EPA) website states: "Of the lakes and streams surveyed, acid rain caused acidity in 75 percent of the acidic lakes and about 50 percent of the acidic streams".

Effect of Acid Rain on Soil

Soil biology and chemistry can be seriously damaged by acid rain. Some microbes are unable to tolerate changes to low pHs and are killed. The enzymes of these microbes are denatured by the acid. The hydronium ions of acid rain also mobilize toxins such as aluminium, and leach away essential nutrients and minerals such as magnesium.

2 H+ (aq) + Mg2+ (clay) 2 H+ (clay) + Mg2+ (aq)

Soil chemistry can be dramatically changed when base cations, such as calcium and magnesium, are leached by acid rain thereby affecting sensitive species, such as sugar maple (Acer saccharum).

Effect of Acid Rain on Forests

Adverse effects may be indirectly related to acid rain, like the acid's effects on soil or high concentration of gaseous precursors to acid rain. High altitude forests are especially vulnerable as they are often surrounded by clouds and fog which are more acidic than rain. It robs the soil of essential nutrients and releases aluminum in the soil, which makes it hard for trees to take up water. Trees' leaves and needles are also harmed by acids. The effects of acid rain, combined with other environmental stressors, leave trees and plants less able to withstand cold temperatures, insects, and disease. The pollutants may also inhibit trees' ability to reproduce. Some soils are better able to neutralize acids than others. In areas where the soil's "buffering capacity" is low, the harmful effects of acid rain are much greater.

Other plants can also be damaged by acid rain, but the effect on food crops is minimized by the application of lime and fertilizers to replace lost nutrients. In cultivated areas, limestone may also be added to increase the ability of the soil to keep the pH stable, but this tactic is largely unusable in the case of wilderness lands. When calcium is leached from the needles of red spruce, these trees become less cold tolerant and exhibit winter injury and even death.

Effect of Acid Rain on Buildings

Acid rain can also cause damage to certain building materials and historical monuments. This results when the sulfuric acid in the rain chemically reacts with the calcium compounds in the stones (limestone, sandstone, marble and granite) to create gypsum, which then flakes off.

CaCO3 (s) + H2SO4 (aq) CaSO4 (aq) + CO2 (g) + H2O (l)

This result is also commonly seen on old gravestones where the acid rain can cause the inscription to become completely illegible. Acid rain also causes an increased rate of oxidation for metals, and in particular copper and bronze. Visibility is also reduced by sulfate and nitrate aerosols and particles in the atmosphere.

Effect of Acid Rain on Human Health

Scientists have suggested direct links to human health. Fine particles, a large fraction of which are formed from the same gases as acid rain (sulfur dioxide and nitrogen dioxide) have been shown to cause illness and premature deaths such as cancer and other diseases.

What is Global Warming?

Definition of Global Warming

Global warming is the observed and projected increases in the average temperature of Earth's atmosphere and oceans. The Earth's average temperature rose about 0.6° Celsius (1.1° Fahrenheit) in the 20th century.

Reasons/Causes of Global Warming

Some of the major contributors of global warming are:

* Carbon Dioxide
* Methane
* Water Vapors
* Nitrous Oxide
* Deforestation

1- Carbon Dioxide Emission

Carbon Dioxide Emission from Burning of Fossil Fuels

In 2002 about 40% of U.S. carbon dioxide emissions stem from the burning of fossil fuels for the purpose of electricity generation. Coal accounts for 93 percent of the emissions from the electric utility industry.

Coal emits around 1.7 times as much carbon per unit of energy when burned as does natural gas and 1.25 times as much as oil. Natural gas gives off 50% of the carbon dioxide, the principal greenhouse gas, released by coal and 25% less carbon dioxide than oil, for the same amount of energy produced. Coal contains about 80 percent more carbon per unit of energy than gas does, and oil contains about 40 percent more. For the typical U.S. household, a metric ton of carbon equals about 10,000 miles of driving at 25 miles per gallon of gasoline or about one year of home heating using a natural gas-fired furnace or about four months of electricity from coal-fired generation.

Carbon Dioxide Emission from Vehicles

About 33% of U.S carbon dioxide emissions come from the burning of gasoline in internal-combustion engines different types of vehicles. Vehicles with poor gas mileage contribute the most to global warming. For example, according to the E.P.A's 2000 Fuel Economy Guide, a new Dodge Durango sports utility vehicle (with a 5.9 liter engine) that gets 12 miles per gallon in the city will emit an estimated 800 pounds of carbon dioxide over a distance of 500 city miles. In other words for each gallon of gas a vehicle consumes, 19.6 pounds of carbon dioxide are emitted into the air. Sports utility vehicles were built for rough terrain, off road driving in mountains and deserts. When they are used for city driving, they are so much overkill to the environment. If one has to have a large vehicle for their family, station wagons are an intelligent choice for city driving, especially since their price is about half that of a sports utility.

Carbon Dioxide Emission from Aviation Services

According to UN's Intergovernmental Panel on Climate Change aviation causes 3.5 percent of global warming that could rise up to 15 percent by 2050.

2- Methane

While carbon dioxide is the principal greenhouse gas, methane is second most important. According to the IPCC, Methane is more than 20 times aseffective as CO2 at trapping heat in the atmosphere. US Emission Inventory 2004 Levels of atmospheric methane have risen 145% in the last 100 years. Methane is derived from sources such as rice paddies, bovine flatulence, bacteria in bogs and fossil fuel production. Most of the world’s rice, and all of the rice in the United States, is grown on flooded fields. When fields are flooded, anaerobic conditions develop and the organic matter in the soil decomposes, releasing CH4 to the atmosphere, primarily through the rice plants.

3- Water Vapor in the Atmosphere Increasing Global Warming

Water vapor is the most prevalent and most powerful greenhouse gas on the planet, but its increasing presence is the result of warming caused by carbon dioxide, methane and other greenhouse gases. Water vapor holds onto two-thirds of the heat trapped by all the greenhouse gases. As the Earth heats up relative humidity is able to increase, allowing the planet's atmosphere to hold more water vapor, causing even more warming, thus a positive feedback scenario.

According to NCDC,” Because the air is warmer, the relative humidity can be higher, leading to more water vapor in the atmosphere”.

4- Nitrous oxide

Nitrous oxide (N2O) a colorless and non-flammable greenhouse gas with a sweetish odor, commonly known as "laughing gas". It is naturally produced by oceans and rainforests. Man-made sources of nitrous oxide include nylon and nitric acid production, the use of fertilizers in agriculture, cars with catalytic converters and the burning of organic matter. All chemical reactions involving sunlight causes break down of Nitrous oxide present in atmosphere.

5- Deforestation

Deforestation comes next after the human activities causing carbon dioxide emissions. Deforestation is being considered responsible up to 25% of all carbon emission entering the atmosphere, by the burning and cutting of about 34 million acres of trees every year, losing millions of acres of rainforests. The destroying of tropical forests alone is throwing hundreds of millions of tons of carbon dioxide into the atmosphere each year. The number of temperate forests is being reduced which account for an absorption rate of 2 billion tons of carbon annually.

Permafrost

Permafrost is a solid structure of frozen soil, extending to depths of 2.200 feet in some areas of the arctic and sub-arctic regions, containing grasses, roots, sticks, much of it dating back to 30,000 years. Permafrost is under 85% of Alaska land surface and much of Canada, Scandinavia and Siberia and holds about 14% of world’s carbon. The hard permafrost on which is built homes and other buildings, can, with rising temperatures, turn into a soft material causing subsidence and damage to buildings, electric generating stations, pipelines and other structures. Ground instability would cause erosion, affect terrain, slopes, roads, foundations and more.

"Permafrost has acted as a carbon sink, locking away carbon and other greenhouse gases like methane, for thousands of year. But there is now evidence that this is no longer the case, and the permafrost in some areas is starting to give back its carbon. This could accelerate the greenhouse effect."

Svein Tveitdal, Managing Director of the Global Resource Information Database (GRID) in Arendal, Norway, a UNEP environmental information center monitoring the thawing of permafrost, told a meeting at the 21st session of the United Nation's Governing Council in Nairobi, Kenya on February 7, 2001.

Tundra

Tundra means ‘treeless plain’ is a name used for environs of the arctic and sub-arctic. The tundra is a biome home to about 1700 kinds of plants, including shrubs, mosses, grasses, lichens and 400 kinds of flowers.

About 50 billion tons of carbon is estimated to be held in a frozen state in the tundra, and now the tundra is beginning to become a source of carbon dioxide. In the 1970's University of California biologist Walter Oechel studied carbon dioxide emissions in the tundra, which until this time had been thought of as a carbon sink. Doing further tests in the 1980's, Oechel discovered that this was no longer the case, that warming temperatures had changed the tundra to a net emitter of carbon dioxide.

“We found to our great surprise that the tundra was already losing carbon dioxide to the atmosphere. So that by the start of these experiments, which was in 1982, the tundra had already warmed and dried enough, that its historic role as a carbon sink had reversed and changed. It was now losing carbon dioxide to the atmosphere. That was totally unexpected." Oechel said.

Total Amount of Carbon Present Everywhere

In Atmosphere: 750 billion tons of Carbon
In Forests: 610 billion tons of Carbon
In Soils: 1580 billion tons of Carbon
In Deep Ocean: 38100 billion tons of Carbon
In Surface Layer of Oceans: 1020 billion tons of Carbon

What is an Ecosystem?

Definition of Ecosystem

An ecosystem is a biological community of interacting living things and their environment. In an ecosystem plants, animals and human beings exist together and depend upon each other for their survival.

OR

An ecosystem is generally an area within the natural environment in which physical (abiotic) factors of the environment, such as rocks and soil, function together along with interdependent (biotic) organisms, such as plants and animals, within the same habitat.

Explanation of Ecosystem

Ecosystems can be permanent or temporary. Ecosystems usually form a number of food webs. Living plants provide food, oxygen and shelter, while dead plants are used as a great source of fossil fuels. Animal provide carbon dioxide used by plants during photosynthesis and excretory waste used as manure for plants. Dead animals decompose to provide basic soil continents. Vital balance is required for survival of all components, malfunctioning can disturb the balance of ecosystem.

Examples of Ecosystem

* Agroecosystem
* Aquatic Ecosystem
* Chaparrel
* Coral Reef
* Desert
* Forests
* Human Ecosystem
* Marine Ecosystem
* Littoral Zone
* Prairie
* Pond Ecosystem
* Rainforest
* Savanna
* TundraUrban Ecosytem

Biomes

Biomes are similar to ecosystems, climatically and geographically defined area of ecologically similar climatic conditions such as communities of plants, animals and soil organisms, often referred to as ecosystems. Biomes are defined based on factors such as plant structures (such as trees, shrubs, and grasses), leaf types (such as broadleaf and needleleaf), plant spacing (forest, woodland, savanna), and climate. Unlike ecozones, biomes are not defined by genetic, taxonomic, or historical similarities. Biomes are often identified with particular patterns of ecological succession and climax vegetation.

Biodiversity

Biodiversity is the variation of life forms within a given ecosystem, biome, or for the entire earth. Biodiversity is often used as a measure of the health of biological systems. The biodiversity found on Earth today consists of millions of distinct biological species, which is the product of nearly 3.5 billion years of evolution. 2010 is the International Year of Biodiversity.

Functions of Ecosystem

From an anthropological point of view, some people perceive ecosystems as production units that produce goods and services, such as wood by forest ecosystems and grass for cattle by natural grasslands. Meat from wild animals, often referred to as bush meat in Africa, has proven to be extremely successful under well-controlled management schemes in South Africa and Kenya. Much less successful has been the discovery and commercialization of substances of wild organism for pharmaceutical purposes. Services derived from ecosystems are referred to as ecosystem services. They may include:

* Facilitating the enjoyment of nature, which may generate many forms of income and employment in the tourism sector, often referred to as eco-tourisms.
* Water retention, thus facilitating a more evenly distributed release of water.
* Soil protection, open-air laboratory for scientific research, etc.

Hovering Satellites

Hovering Satellites

Satellites are man-made objects revolve around the earth for certain scientific purposes. The satellites apparently static in relation to earth are put into such orbits that their orbital velocity cancels the spinning velocity of earth and both becomes synchronized, such satellites are called ‘Hovering Satellites’.

Geostationary Orbits

The orbits in which such hovering satellites appear stationary from the earth are called geostationary orbits.

Explanation of Hovering Satellites

* Hovering satellites are usually situated at the height of about 35600km above the earth. A number of hovering satellites are situated at various parts around the earth for instant communication facilities round the globe.

* Communication satellites provide reliable and continuous telephone and TV transmission throughout the globe and change their position with respect to ground stations.

* Surveillance satellites placed either in geostationary orbit or in lower orbits, gather info about enemy troops and military installations through visual and infrared imaging.

* Weather satellites provide daily info about changing weather conditions expected to prevail in the region.

* Research satellites provide info about earth’s magnetic field and cosmic rays e.g. MRI Skylab.

* Moving satellites do not serve for establishing communication links between different continents as communication through space require these satellites to have specific position relative to earth for efficient transmission of signals between ground station and a satellite.

A - C

ACTH

Adreno Cortico Tropic Hormone

ADH

Antidiuretic Hormone$Alcohol Dehydrogenase

ADP

Adenosine Di Phosphate

AFM

Atomic Force Microscope

AHF

Anti-Haemophilic Factor

AIDS

Acquired Immune Deficiency Syndrome

ALGOL

Algorithmic Language

AMF

Action Message Format

AMU

Atomic Mass Unit

APS

Advanced Photo System

APS-C

Advanced Photo System type-C

AR

Aqua Regia/

Androgen Receptor

ARDS

Adult Respiratory Distress Syndrome

ATM

Automated Teller Machine/

Asynchronous Transfer Mode

ATP

Adenosine Tri Phosphate

ATS

Anti Tetanus Serum

AV

Atrio Ventricular

BASIC

Beginners All-Purpose Symbolic Instruction Code

BBS

Bulletin Board System

BCG

Bacillus Calmette Guerin/

Ballisto Cardio Graphy

BeV

Billion Electron Volt

BIT

Binary Digit

BJT

Bipolar Junction Transistor

BMR

Basal Metabolic Rate

BSD

Berkeley Software Distribution

BTU

British Thermal Unit

BWR

Boiling Water Reactor

CAD

Computer Aided Design

CAG

Cytosine Adenine Guanine

CAL

Common Application Language

CAT

ScanComputed Axial Tomography Scan

CDMA

Code Division Multiple Access

CFC

Chloro Fluoro Carbon

CGI

Common Gateway Interface/

Computer Generated Imagery

CMOS

Complementary Metal Oxide Semiconductor

CNG

Compressed Natural Gas

COBOL

Common Business Oriented Language

CPR

Cardio Pulmonary Resuscitation

CPU

Central Processing Unit

CRO

Cathode Ray Oscilloscope

CRT

Cathode Ray Tube

CSS

Cascade Style Sheet

CT Scan

Computed Tomography Scan

CU

Control Unit

CW

Continuous Wave

D - L

DBMS

Database Management System

DBS

Digital Broadcast Satellite/

Deep Brain Stimulation

DDT

Dichloro Diphenyl Trichloro Ethane

DNA

Deoxy Ribonucleic acid

ECG

Electro Cardio Graphy

EEG

Elctro Encephalo Graphy

EM

Electron Microscope

EMF

Electro Magnetic Field/

Electro Motive Force

ENIAC

Electronic Numerical Integrated And Computer

EROM

Erasable Read Only Memory

ERP

Enterprise Resource Planning

EST

Expressed Sequence Tag

ETT

Endo Tracheal Tube

FAD

Flavin Adenine Dinucleotide

FMN

Flavin Mono Nucleotide

FORTRAN

FORmula TRANslation language

FSH

Follicle Stimulating Hormone

GAC

Guanine Adenine Cytosine

GeV

Giga Electron Volt

GIGO

Garbage In Garbage Out

GMT

Greenwich Mean Time

GPS

Global Positioning System

GSM

Global System for Mobile communication

HDL

High Density Lipoprotein

HDLM

Handheld Device Markup Language

HDPE

High Density Polyethylene

Hi-Fi

High Fidelity

HIV

Human Immunodeficiency Virus

HSD

High Speed Data

HST

Hubble Space Telescope

HTML

Hyper Text Markup Language

HWT

Heavy Water Reactor

IPC

Inter Process Communication

IRDS

Infant Respiratory Distress Syndrome

IT

Information Technology

JSP

Java Server Pages

KWH

Kilo Watt Hour

LAN

Local Area Network

LASER

Laser Amplification by Stimulated Emission of Radiation

LCD

Liquid Crystal Display

LDI

Light Dependent Inductor

LDL

Low Density Lipoprotein

LDPE

Low Density Polyethylene

LED

Light Emitting Diode

LPG

Liquified Petroleum Gas

LWR

Light Water Reactor

M - R

MAF

Million Acre Feet

MASER

Microwave Amplification by Stimulated Emission of Radiation

MBTU

Million British Thermal Unit

MeV

Million Electron Volt

MHD

Magneto Hydro Dynamics

MIDI

Musical Instrument Digital Interface

MIMD

Multiple Instruction Multiple Data/

Multiple Data Stream

MMS

Multimedia Messaging Service

MRI

Magnetic Resonance Imaging

NMR

Nuclear Magnetic Resonance

NPN

Negative Positive Negative(Diode)

NTP

Normal Temperature & Pressure/

Nitrogen Triphosphate

OPV

Oral Polio Vaccine

ORS

Oral Rehydration Salts

OS

Operating System

OSI

Open Systems Interconnection

PABA

Para Amino Benzoic Acid

PCM

Pulse-Code Modulation/

Protein Calorie Malnutrition

PCR

Polymerase Chain Reaction

PDA

Personal Digital Assistant

PERL

Practical Extraction & Reporting Language

PET

Positron Emission Tomography

PHP

Hypertext Preprocessor

PNP

Positive Negative Positive (Diode)

PROM

Programmable Read Only Memory

PTCA

Percutaneous Transluminal Coronary Angioplasty

PTFE

Poly Tetra Flouro Ethylene

PTH

Para Throid Hormone

PTC

Poly Vincyl Chloride

PWR

Pressurized Water Reactor

RADAR

Radio Angle Direction And Range

RAM

Random Access Memory

RBC

Red Blood Cell

RDS

Respiratory Distress Syndrome/

Radio Data System

RNA

Ribo Nucleic Acid

ROM

Read Only Memory

RQ

Respiratory Quotient

RSS

Really Simple Syndication

S -X

SA

Sino Atrial

SARS

Severe Acute Respiratory Syndrome

SEM

Scanning Electron Microscope

SEO

Search Engine Optimization

SGML

Standard Generalized Markup Language

SIMD

Single Instruction Multiple Data

SLBM

Submarine Launched Ballistic Missile

SLR

Single-Lens Reflex

SMS

Short Messaging Service

SOAP

Simple Object Access Protocol

SONAR

Sound Navigation And Ranging

STD

Sexually Transmitted Disease/

Subscriber Trunk Dialing

STEM

Scanning & Transmission Electron Microscope

STM

Scanning Tunneling Microscope/

Software Transactional Memory

STP

Standard Temperature & Pressure

TCP/IP

Transmission Control Protocol/

Internet Protocol

TEM

Transmission Electron Microscope

TNT

Tri Nitro Toluene

TPN

Triphospho Pyridine Nucleotide/

Total Parenteral Nutrition

UHF

Ultra High Frequency/

Ultra High Fidelity

UPS

Uninterruptible Power Supply

VCR

Video Cassette Recorder

WAN

Wide Area Network

WAP

Wireless Application Protocol

WBC

White Blood Cell

WLL

Wireless Local Loop

WR

Water Reactor

WSDL

Web Services Description Language

WWW

World Wide Web

W3C

World Wide Web Consortium

XHTML

Extensible Hypertext Markup Language

XML

Extensible Markup Language

XSL

Extensible Stylesheet Language

XSLT

Extensible Stylesheet Language Transformation

Polycystic Kidney Disease

"PKD" stands for polycystic kidney disease characterized by the formation of multiple cysts on kidney surface causes increase in its size and weight. The weight of cyst filled kidney can reach 20-30 pounds. It is the most common heredity kidney disorder passes down through families. If both parents are carrier of this disease there is 50% chance for child to develop this disease but if one of the parents carries it the chance of its occurrence in child remains 25%. In this case child does not develop it but simply passes it to the next generation. It occurs in two forms; Autosomal dominant PKD and Autosomal recessive PKD. Autosomal dominant PKD shows symptoms in adulthood while Autosomal recessive PKD shows symptoms in infancy and early childhood.

In Autosomal dominant PKD there is chance for a person to live for several years so it is also called "adult polycystic kidney disease". Symptoms of Autosomal dominant PKD are abdominal pain or pain in back and lower portion,excessive urination at night,headache, high blood pressure,abnormal heart valves,kidney stones, nail abnormalities,drowsiness and painful menstruation etc. Some other severe conditions include hematuria,aneurysms (bulges in walls of blood vessels) and direvticulosis (small pouches bulge outward through the colon). Hematuria (blood in urine) can be classified into microscopic and gross hematuria. In microscopic hematuria blood spots are so small that they can only be seen through a microscope. While in gross hematuria large spots of blood can be seen through naked eye.

Autosomal recessive PKD is rare form caused by mutation in Autosomal recessive PKD gene (PKHD1). Signs of this form of PKD appear before birth so it is also called "infantile PKD". In many cases child with Autosomal recessive PKD develops kidney failure before reaching adulthood. Severity of this condition varies from case to case as in some cases baby die after some hours or days due to respiratory difficulties or total respiratory failure. Its symptoms are high blood pressure,urinary tract infection, frequent urination, effects on liver and spleen, low blood cells count, varicose veins and hemorrhoids (formation of masses or clamps of tissues within anal canal) etc. Growth factor is considered a primary feature of Autosomal recessive PKD as child shows less growth activity (smaller in size) than average growth rate.

It is important to remember that there is no specific cure for PKD. But antibiotics can be used for pain reduction,high blood pressure and for urine related problems. Dialysis and kidney transplantation are also used as alternative methods of cure to avoid its severity.

What is Cell Nucleus?

Cell nucleus is spherical or semi spherical body present usually in the center of eukaryotic cells. In prokaryotic cell, nuclear material is dispersed throughout the cytoplasm without a definite membrane. Nucleus is often called 'Brain Of The Cell' as it contains cell's hereditary material DNA and coordinates its all metabolic activities including growth, metabolism, protein synthesis and reproduction (cell division) etc. As far as its size is concerned it occupies about 10 percent of total eukaryotic cell's volume.

Nuclear membrane is nuclear envelope that separates the nuclear material from the cellular cytoplasm. It is double layered membrane that encloses the nuclear material during most of the cell's life cycle. These two unit membranes run parallel to each other with a space between them called perinuclear space which is an electron transport area. At some places outer membrane gives out tubular structures called endoplasmic reticulum. Annuli are openings in nuclear envelope through which nucleoplasm communicates with the cytoplasm. These nuclear pores regulate the passage of molecules between the nucleus and cytoplasm allowing them to pass through the nuclear membrane. It is believed that these pores can open and close but its definite mechanism is not clear. During cell division (mitosis), the nuclear membrane disintegrates into vesicles which disappear in the cytoplasm. But soon at the reformation stage when two cells complete their formation and the chromatin begins to appear these vesicles again combine to reform nuclear membrane.

The semi-fluid matrix bounded by nuclear membrane is called nucleoplasm. Within nucleoplasm, a mass of thin fibrils called chromatin is present. This chromatin network is the actual site of genetic activities as it contains DNA and become highly coiled at the time of cell division to form chromosomes. Chromatin is so organized that it gives reticulate appearance. About 6 feet of DNA is present in every human cell, divided into 46 individual molecules (chromosomes). Chromosomes are chemically composed of DNA, RNA, Histone (basic proteins) and Hertones (non histone proteins). Calcium is also present in it. Genes, the fundamental units of heredity, are present on chromosomes on specific position called locus.

The nucleus also contains one or more dark, spherical, colloidal bodies called nucleoli (singular; nucleolus). Nucleolus is associated with a special region called 'Nucleolar Organizing Region' present in the chromosome. It is rich in RNA which passes to cytoplasm to take part in protein synthesis. Nucleoli are involved in manufacturing ribosomes. A nucleolus consists of RNA, acidic and basic dyes, phospholipids and alkaline phosphates. Under microscope nucleolus looks like a large dark spot within the nucleus. A nucleus may contain several nucleoli which sometimes merge to form a single and large nucleolus.

Reiki - A technique for Stress Reduction and Healing

Reiki,a Japanese technique for stress reduction and for healing purposes introduced in Canada and US in 1970s by Mrs.Hawayo Takata. Reiki is made up of two Japanese words,"Rei" means God's wisdom "ki" means "life force energy. So Reiki means "Spiritually guided life force energy" a technique based upon the idea of unseen life force energy flows through us.Reiki was founded by Dr Mikao Unsi,a Japanese Buddhist in 1870s. He experienced a profound spiritual enlightenment after a 21 days period of fasting and meditation. He began to deliver this technique to other people as well and opened his teaching clinic in Japan.

Reiki treats the whole person with his physical and spiritual problems. It is a lying on hands healing technique to balance subtle energies within the body. During the treatment patient is laid down on massage table dressed in loose garments. Atmosphere during session is kept relaxing using dimmed lights with complete silence or with light music. Reiki master places his hands on different parts of body for 2-5 minutes. Energy flows through the palms of his hands to the recipient's body. During session It is not necessary to touch the patient body. Some reiki masters hover their palms few inches above the body. Energy flow to the effected part is automatic regardless of hands position and sequence of hands placements.

Unlike other techniques it is not learned but is transferred from reiki master to his students during class. It is taught in three levels,level 1 & 2 in one day class. Level 3,more intensive,longer involves a ritual(Attunement) and learning of placing hands for treatment. Attunement is the initiation to open up crown,heart and palm chakras to allow "Rei" energies to flow through. The time period for its training can be varied. This technique is not difficult to learn as it does not depend upon intellectual capacity of a person. No specific belief or intellectual capacity is required to learn it. An important reason for its unique way of learning is to avoid its misuse by people for illicit purposes so it is transferred to student not learned through written material to keep its spiritual nature sacred.

There are also some myths and misconceptions about this technique. First one is that it is a related to religion or any dogma or belief. No it is not true,as it is purely spiritual in nature and promotes spiritual growth of person. Second misconception is that after treating a patient the energy level of reiki master get lowered. It is again wrong as "rei" energies are infinite and can not run out. If somebody feels tired after treating a patient it is because of his or her own internal weakness not because of reiki treatment. Thirdly it is considered a massage therapy as it is also used in massage therapies but it is not true as well. As discussed earlier it is energy based technique not involving bones and tissues. Another misunderstanding is about the process of attunement that it will open the doors of spiritual world and a person will be able to find solution about all spiritual problems. It is not so as well though reiki promotes spiritual growth but assuming it the way to spiritual world would be an exaggeration.