Die Walküre (The Valkyrie) is an opera by Richard Wagner.  It is the second of the four operas that together tell a story called Der Ring des Nibelungen (The Ring of the Nibelung).  The story continues from the first opera which was called Das Rheingold. It is a very beautiful piece.

Die Walküre was first performed on 26 June 1870 in Munich.  The first performance that was part of the whole Ring cycle took place on 14 August 1876.

The story of the opera

Act One
The opera starts with a storm.  The young man Siegmund is out in the storm and comes to a house.  The house belongs to Hunding who lives there with his wife Sieglinde.  An ash tree is growing in the middle of the house.  Siegmund and Sieglinde are twins who were separated as children, so neither of them knows who the other one is.  Their father is Wotan, the chief god, but they don't know this either.  Their mother was a mortal (an ordinary person, not a goddess) or perhaps a she-wolf, which is how the goddess Fricka refers to her.

Sieglinde lets Siegmund into the house and gives him a drink of mead.  They start to fall in love.  Hunding arrives and asks Siegmund who he is.  Siegmund says that his name ought to be Woeful because he has had an unhappy life.  When he was small he came home once and found his house burned down, his mother murdered and his twin sister had been abducted (taken away).  He then remembers that some years later he went to help a young lady who had been forced to marry a cruel man.  He had killed some of the man's friends.  Hunding realizes that he himself was this man, so that he is Siegmund's enemy.  He says to Siegmund that he can sleep in his house tonight because this is a law of hospitality, but in the morning he will have to fight him.

Sieglinde goes to prepare a drink for her husband.  She puts a drug in it which will make Hunding sleep deeply.  Siegmund meanwhile is thinking about something his father had promised him.  He had told him that he would thrust a magic sword called "Nothung" into a tree.  No one would get that sword until, one day, when Siegmund found himself in great difficulty, he would be able to pull it from the tree and use it.

Sieglinde enters and tells Siegmund a story about how, on the day she was forced to marry Hunding, an old man had come into the house and thrust a sword into the ash tree in the middle of the room.  They start to realize that they are brother and sister,  but it does not stop them from falling in love and they sing passionately about their love for one another.  Siegmund pulls the sword from the tree and the two lovers embrace.

Act Two
Wotan is the chief god, whom we heard in Das Rheingold. He is trying to get rid of the curse of the Rheingold, and has built a grand plan around Siegmund. Wotan tells his daughter Brünnhilde that she must make sure that Siegmund wins the fight with Hunding.  Brünnhilde (the out-of-wedlock daughter of Wotan and Erda, the Earth-Mother goddess) has the power to do this.  She is one of eight daughters of Wotan who are Valkyries (German: Walküren).  Their job is to collect the dead bodies of brave heroes who have died in battle and take them back to Valhalla, the house of the gods.

Wotan's wife Fricka arrives in a chariot pulled by a ram.  Brünnhilde disappears, and there follows a big argument between husband and wife.  Fricka says to Wotan that Siegmund and Sieglinde must be punished for breaking Hunding's marriage, and for loving one another because brothers and sisters are not allowed to be lovers (this is called "incest").  She says that she herself is the goddess of marriage and must make sure that marriage laws are obeyed. Fricka says that the gods will all be disgraced. Wotan says that he went to the world to have children with mortal women because the gods needed a race of heroes who would protect them.  But Fricka says to Wotan that he is wrong: Siegmund cannot be a free hero if he is being protected by Wotan. Giving in, Wotan now tells Brünnhilde that she must leave Siegmund to his fate.

Sieglinde tells Siegmund that she feels guilty and that he ought to leave her, but they are desperately in love.  When she hears Hunding's horn she imagines that Siegmund will be torn apart by the dogs and she faints.  Brünnhilde pities Siegmund. She tells Siegmund that he must follow her to Valhalla.  When Siegmund asks whether he can take Sieglinde with her Brünnhilde says that he cannot do this.  Siegmund refuses to go.  Brünnhilde tells him that he cannot escape his fate.  Siegmund continues to plead with Brünnhilde, and in the end she is so moved that she changes her mind. She breaks Wotan's order, and says that she will protect Siegmund in battle.  Hunding appears and the two men fight.  Brünnhilde protects Siegmund with her shield.  Siegmund is nearly winning when suddenly Wotan appears and smashes Siegmund's sword into pieces. Hunding kills Siegmund.

Act Three

The other Valkyries are wondering where Brünnhilde is.  They see her coming on her horse, but instead of a hero she is carrying a woman (it is Sieglinde).  The Valkyries are angry with Brünnhilde because she disobeyed Wotan.  Sieglinde wants to die, but when she is told that she has a baby in her womb she asks Brünnhilde to save her.  She escapes into the forest with bits of Siegmund's sword.  One day the baby she is now bearing will grow up, become a hero, and use the bits to make another sword.

Wotan goes to the Valkyries.  He is furious with Brünnhilde because she disobeyed him.  He punishes her.  He tells her that she is no longer a Valkyrie.  She will fall asleep on a rock and any man who finds her can have her.  Brünnhilde pleads with Wotan.  She asks him whether he could, at least, put a fire round her so that the only man who could get her would be a hero.  In the end Wotan agrees.  Loge, the god of fire, arrives and lights the fire.  At the end of the opera Brünnhilde is asleep on the rock, surrounded by the fire.  There she will stay until, one day, a hero comes to rescue her.

The music of the opera

The music contains many wonderful moments.  The most famous bit is the beginning of Act Three where the Valkyries are riding on their horses.  This music is known as The Ride of the Valkyries.  It is very dramatic music.  The very beginning of Act One is also very dramatic.  The music describes a storm.  The orchestra is a very large one, including special tubas which are known as "Wagner tubas".  There are no separate arias in these operas: all the sections flows into one another.  Sometimes a character has a section when they are telling a story.  There are beautiful sections like the one in Act One where  Siegmund is remembering about his father and the sword, or the love music between Siegmund and Sieglinde.  By using leitmotifs (music which goes with certain ideas or characters) he gets many subtle effects.  When Siegmund looks at the ash tree we hear the sword motive because the sword is in the tree, although at that moment he does not know about it.  We also hear Wotan's theme when Siegmund talks about his father.  We (the listener) know who his father is, but Siegmund does not.  The music tells us lots of things that the characters in the story may not understand.  This makes the music very powerful and exciting.

The other operas
The first opera in the cycle is Das Rheingold.
The third opera in the cycle is Siegfried.
The fourth opera in the cycle is Götterdämmerung.
The whole cycle is called Der Ring des Nibelungen.

References

Operas by Richard Wagner
1870s operas

Die Walküre


A bicycle (or bike) is a small, human powered land vehicle with a seat, two wheels, two pedals, and a metal chain connected to cogs on the pedals and rear wheel. A frame gives the bike strength, and the other parts are attached to the frame. The name comes from these two words - the prefix "bi-" meaning two, and the suffix "-cycle" meaning wheel. It is powered by a person riding on top, who pushes the pedals around with his or her feet.

Riding bicycles, which is also called cycling, is an important way to travel in several parts of the world. The most popular type of cycling is Utility cycling.  It is also a common recreation, a good form of low-impact exercise, and a popular sport. Road bicycle racing is the second most popular spectator sport in the world.
Bicycling uses less energy per mile than any other human transport.

Invention

In 1817 a German professor, Baron Karl von Drais, created the first two-wheeled bicycle. It was made of wood and had two wheels. The front wheel could be turned using the handlebars in order to steer the bike. However, it did not have pedals, so the rider would have to push their feet on the ground to make it move.

In the 1860s, French inventors added pedals to the front wheel. However, it took a lot of effort to turn the pedals.  Later inventors made bikes out of metal only, and made the front wheel very big, giving higher speed. This design was called the penny-farthing bicycle. However, it was difficult to ride, since it could fall easily and the rider would fall far.

Several improvements were made in the 1880s and '90s. In 1885, the safety bicycle was invented. This had two wheels the same size so that the rider could sit at a lower height. It was called the safety bicycle because it much easier to ride than the penny-farthing. When stopping, the rider can simply put down a foot instead of completely dismounting.  Instead of pedaling and steering with the front wheel, the safety bicycle steers with the front wheel while the pedals turn the back wheel using a chain. Brakes operated by hand levers on some bikes also increased safety.

In 1888, Scottish inventor John Boyd Dunlop re-invented a type of tire which was filled with air. This made safety bicycles more comfortable. Soon, the freewheel was invented. This was a device inside the hub of the back wheel that allowed the wheel to spin even if the rider wasn't pedaling.  However, this meant the rider could no longer stop the bike by backpedaling.  As a result, better hand brakes were invented, and a different type of brake which could stop the bike if the pedals were turned backwards.  Later inventions included better brakes, and gears which made cycling over hills much easier. During this time the bicycle became very popular.

Basic Design
Basic components common to most bikes include a seat, pedals, gearing, handlebar, wheels, and brakes, all mounted on a frame. The majority also have a gear shifter. The cyclist's feet push the pedals to make them go around in circles, which moves the chain, which turns the back wheel of the bike to make the bike move forwards. The front wheel is connected to the handlebar, so turning the handlebar from side to side swivels the front wheel which steers the bike.

Types of Bicycles

 The city bicycle is made for errands and commuting in cities.  It has a comfortable seat but is heavy.  It has front and back lights and a bell, and carriers for small cargoes.   It has mudguards to keep water and mud from spraying the rider.  The rider sits upright for comfort and easy steering in traffic.  "Bike share" systems usually provide " city-style bikes".
 The mountain bicycle is used for riding on rough roads.  They have many speeds (usually more than 20), wide tires, and strong wheels.  The tire is specially designed to ride smoothly on hills, grass, and mountains.

 The difference between a woman's bicycle and other bicycles is the location of the top tube. When women began to ride bikes, they wore long skirts. The manufacturers of bicycles changed the location of the top tube to make it easier for women to sit down on them while wearing a skirt. Some utility bicycles are similar, for riders who make frequent stops.
 The tandem bicycle is made for two people. It has two pairs of pedals. The cyclists sit one behind another. The first cyclist steers the bicycle. There are bicycles for three and more people. There was a bicycle for 40 people.
 Folding bicycles can easily be stored in a small place or carried a long distance on an airplane or other public transport.
 Electric Bicycles have electric motors, usually inside the hub of either the front or rear wheel. You can choose to ride using the motor only, or with pedals only or with both together. In the U.S. the federal government has set a limit of 750 Watts and a top electric-powered speed of 20MPH to have only the rules that apply to bicycles and no extra restrictions such as operator license, vehicle license, registration or insurance requirements.
 A road bicycle usually has narrow wheels, less than 1" (25 mm) wide, with a frame that is much lighter than a mountain bicycle.  Road bikes are efficient for longer distances.  Many have clips to attach your shoes, rather than just pedals.  There are variations, as some road bicycles have regular tires.  Road bicycle racing is a popular sport.
 Recumbent bicycles come in several styles, but all of them have pedals in front of the seat, and the rider leans back while riding.  This is more comfortable for most people, but cost more.  Some types are lower to the ground, so it might be harder to see in traffic.  The fastest bikes in the world are recumbents.

Safety
Many thousands of people are hurt every year in bicycle accidents, and hundreds die. Careful riding helps prevent accidents. When riding on streets, it is safest to ride on the same side of the street that cars drive (which would mean riding on the right side of the road in countries where people drive on the right side of the road, and riding on the left in countries where people drive on the left).  To avoid hitting people, riders must obey signs that say "no bicycling", even if it does not seem to make sense at the time.  Low light makes bicycle lighting important. It may not be safe to ride when it is dark. Riders wear reflective clothing to be safer in low light.  Wearing a helmet makes bicycle riding safer. Wearing a helmet does not mean that somebody cannot be hurt if they crash their bicycle, but it makes being hurt less likely. Some bicycles have bells or horns that the rider can use to warn other people that they are riding by them.

Many places have a bicycle path linking houses with shops, schools and stations.  These make bicycling safer, letting cyclists stay away from busy motor traffic on dangerous roads.

Related pages
 World Bicycle Day
 Tour de France
 Unicycle
 Tricycle
 Tandem trike

References

Human-powered vehicles
Cycling

Bicycle


Sexual attraction is an attraction to other members of the same species for sexual or erotic activity. In many species this does not always mean a sexual act; indeed, some sexual behavior among primates is mostly a social activity.

In humans
What is sexually attractive to humans may change by culture or place. The sexual attraction of one person to another depends on both people.

Much of human sexual attractiveness is physical (see beauty). This involves the impact one's appearance has on the senses, especially in the beginning of a relationship:

 Visual perception (how the other looks);
 Olfaction (how the other smells, naturally or artificially; the wrong smell may be repellent);
 Audition (how the other's voice and/or movements sound).
 Vibes, sensory perception (generally biased) of another person based on one's own view or from influence from others. (negative or positive).

Types

Heterosexuality
Homosexuality
Gay
Lesbian
Bisexuality
Pansexuality

Related pages
Casual sex
Human bonding
Human sexuality
Interpersonal relationship
Intimacy
Love
Lust
Sexual arousal

References

Other websites
 Sexual Attraction Among Humans
 FaceResearch  – Scientific research and online studies on the role of faces in sexual attraction
 Reunions Set Off Sex Urges, Article on sexual attraction among birth relatives.
 www.lookism.info deconstruction of attraction and beauty standards

Human sexuality

Sexual attraction


This article is about the visible spectrum. For all other uses see: Spectrum (disambiguation)

A spectrum, plural: spectra, is a band of several colours: violet, indigo, blue, green, yellow, orange and red. A spectrum can be seen if the Sun's light is passed through a prism and allowed to gather on a white screen. This visible spectrum is part of the larger electromagnetic spectrum. Spectroscopy is the study of spectra.

A natural example of a spectrum is a rainbow. The word spectrum was first used by scientists studying optics. They used the word to describe the rainbow of colors in visible light when separated using a prism.  The spectrum seen when light passes through a prism is an example of the dispersion of light.  The material from which the prism is made has a different  refractive index n than air.  Usually, nprism is greater than nair, and nair is taken to be approximately one. This implies that light travels a little slower in the material of the prism than in the space surrounding it.  The angle of refraction can be determined from the angle of incidence and the refractive indexes using Snell's law.

The reason why the white light separates into in its component colors instead of remaining white is because the shorter wavelengths are refracted, or bent, more than the longer wavelengths.  Thus, red, having the longest visible wavelength, will appear closest to the line perpendicular to the surface of the material (the normal), that is, it will be bent the least.  Violet light, with the smallest wavelength  in the visible spectrum, will be bent the most.  The rainbow produced will always be in the same order: red, orange, yellow, green, blue, indigo, violet.

References

Related pages
Primary colour

Light

Spectrum


Nuclear physics is the part of physics that studies the nucleus of the atom. Everything on the earth is made up of atoms; they are the smallest part of a chemical element that still has the properties of that specific element. When two or more atoms combine they create what we know as the molecule, which is the smallest part of a chemical compound which still has the properties of that specific compound. Understanding the structure of atoms is key in studies such as physics, chemistry, biology, etc.

Atoms

Structure
Atoms are made up of electrons, neutrons, and protons. The protons and neutrons are in the center of the atom, which is called the nucleus. The protons and neutrons are the heaviest part of the atom and make up most of its mass. The electrons move around the nucleus very quickly, making what is called an electron cloud. The electron cloud has a very small mass, but it makes up most of the space of the atom. The electrons have a negative charge, and the protons have a positive charge. Due to the charges in the atom, that is how the atom stays together, by attraction of the electric charges present in the atom.

Properties
Atoms have different features that single out one atom from another, and show how each atom can change in different conditions. These properties include atomic number, mass number, atomic mass and weight, and isotopes.

Forces acting
In an atom there are three fundamental forces that keep atoms together. electromagnetic force, strong nuclear force, and weak nuclear force. The electromagnetic force keeps the electrons attached to the atom. The strong nuclear  force keeps the protons and neutrons together in the nucleus. The weak nuclear force controls how the atom decays.

Quantum
In the early 20th century, scientists had trouble explaining the behavior of atoms using their current knowledge of matter. So to deal with this they made a brand new way to view matter and energy, and they called it quantum theory. Quantum theory explains how matter acts both as a particle and a wave.

Radiation

Atoms emit radiation when their electrons lose energy and drop down to lower orbitals. The difference in energy between the orbitals determines the wavelength of the given radiation. This radiation can be shown by visible light or shorter wavelengths.

Nuclear energy

Nuclear physics


Lyrics are the words to a song. A person who writes lyrics is called a lyricist.

The lyrics of a song will usually have a meaning. Some times the meaning is easy to find but other times it can be very difficult to know what the lyrics mean. Some lyrics are so strange that it is nearly impossible to understand them. In such cases, people tend to look more at the form, articulation, meter, and symmetries of the lyrics instead of looking at their meaning.

There are many websites that have the lyrics to songs. This may be a bad thing since many web sites include copyrighted lyrics without permission from the copyright holder. The United States Music Publishers' Association (MPA), which represents sheet music companies, created a campaign against such sites in December 2005. MPA president Lauren Keiser said that the sites are "completely illegal" and that he wanted to see some site operators put in prison.

Etymology and usage
"Lyric" is from the Greek; a lyric was originally a song sung with a lyre.

A lyric poem is one that expresses a subjective, personal point of view.
 I would be the Lyric
 Ever on the lip,
 Rather than the Epic
 Memory lets die.
 –Thomas Bailey Aldrich

The word lyric was used for the "words of a popular song" about 1876  for the first time. The plural lyrics was used only in referring to the words of several songs. That it is used for the words of a single song as its lyrics became increasingly common (probably because of the association between lyrics and the plural form words), and is common in modern usage of today's society. Use of the singular form lyric is still grammatically acceptable.

References

Poetry

hu:Líra (műnem)

Lyrics


Liste over fylker i Illinois. Den amerikanske delstaten Illinois består av 102 fylker (counties).

 Adams County
 Alexander County
 Bond County
 Boone County
 Brown County
 Bureau County
 Calhoun County
 Carroll County
 Cass County
 Champaign County
 Christian County
 Clark County
 Clay County
 Clinton County
 Coles County
 Cook County
 Crawford County
 Cumberland County
 DeKalb County
 DeWitt County
 Douglas County
 DuPage County
 Edgar County
 Edwards County
 Effingham County
 Fayette County
 Ford County
 Franklin County
 Fulton County
 Gallatin County
 Greene County
 Grundy County
 Hamilton County
 Hancock County
 Hardin County
 Henderson County
 Henry County
 Iroquois County
 Jackson County
 Jasper County
 Jefferson County
 Jersey County
 Jo Daviess County
 Johnson County
 Kane County
 Kankakee County
 Kendall County
 Knox County
 LaSalle County
 Lake County
 Lawrence County
 Lee County
 Livingston County
 Logan County
 Macon County
 Macoupin County
 Madison County
 Marion County
 Marshall County
 Mason County
 Massac County
 McDonough County
 McHenry County
 McLean County
 Menard County
 Mercer County
 Monroe County
 Montgomery County
 Morgan County
 Moultrie County
 Ogle County
 Peoria County
 Perry County
 Piatt County
 Pike County
 Pope County
 Pulaski County
 Putnam County
 Randolph County
 Richland County
 Rock Island County
 Saline County
 Sangamon County
 Schuyler County
 Scott County
 Shelby County
 St. Clair County
 Stark County
 Stephenson County
 Tazewell County
 Union County
 Vermilion County
 Wabash County
 Warren County
 Washington County
 Wayne County
 White County
 Whiteside County
 Will County
 Williamson County
 Winnebago County
 Woodford County

Referanser

Eksterne lenker

Illinois

Liste over fylker i Illinois


A basilica is a large, important church. The word can also be used for an Ancient Roman building that was used for law and meetings. The word "basilica" is Latin which was taken from the Greek "Basiliké Stoà".

Nowadays the word is used in three ways:
 A Roman Catholic church that has been given the right to use that name, by the Pope. Only some large important churches have this right.
 An Ancient Roman basilica
 People who write about architecture often use the word "basilica" to mean a building that is shaped like an Ancient Roman basilica.

History

Ancient Rome

A Roman basilica was a large hall built for meetings, business and law. A Roman basilica usually had the doors at the long sides of the building. At each end was a semi-circular part where the judges sat. The building usually had two rows of columns, which made a high central part and a lower aisle on either side. The light came in from windows above the columns. As the Roman Empire spread, every city had a basilica.

Early Christian basilicas
Early in the 4th century (312 AD), the Roman Emperor Constantine made Christianity the legal religion of the Roman Empire. The Christians who had been worshipping secretly in private houses now wanted to build churches. They did not want the churches to look the same as Roman Temples. They built them to look more like Roman Basilicas. A basilica was a good plan for a Christian church because lots of people could fit inside, and the aisles were useful for people to move around. The semi-circular part at one end, the apse, was just right to put the altar. Christian basilicas usually have the door at one end, rather than at the side. In front of the door there was often a courtyard called an atrium. Most of these atriums have gone, but churches often have a town square or a market place in front of them.

Some of the oldest Early Christian basilicas were four that were begun in Rome by the Emperor Constantine. Three of them are still standing, but they have had many changes in the last 1,700 years. These are the basilicas of Santa Maria Maggiore, St. John Lateran and St. Paul's outside the Walls. The fourth basilica was 'Old St. Peter's which was replaced in the 16th and 17th centuries by the present St. Peter's Basilica. Other Early Christian Basilicas were built in Greece and the Holy Land.

Present-day basilicas
Some basilicas are called "Ancient Basilicas". These have been called basilicas since Early Christian or Medieval times. It is their traditional name. Ancient Basilicas include the Church of the Holy Sepulchre in Jerusalem, the Basilica of San Vitale in Ravenna and the Basilica of San Lorenzo in Rome. The four other ancient basilicas of Rome are called the "Major Basilicas". Each Major Basilica has a throne for the pope and an altar that is specially for the pope to celebrate mass. No-one else can use that altar without the pope's permission. All the other basilicas are called "Minor Basilicas".

Nowadays, for a church to be called a Minor Basilica, it has to be given some special privileges or rights by the pope in a document called a "Papal Brief". When a church has been made a basilica, the clergy then carry some special symbols when they are in procession. In 2008 there were more than 1,600 basilicas in the world.

Why do churches become basilicas?

Ancient basilicas
Many churches are given the name "basilica" to show that they are special in some way. There are very few ancient basilicas that were built on ground associated with Jesus. They are thought of as some of the holiest Christian sites in the world. These include the Basilica of the Annunciation in Nazareth, the Basilica of All Nations where Jesus prayed on the Mount of Olives and the Basilica of the Holy Sepulchre in Jerusalem. The Basilica of the Holy Sepulchre is very unusual because the church is shared by the Catholic and Orthodox Churches.

Martyrs
Other ancient basilicas are places where a saint was martyred (put to death). One of these is the Basilica of Saint Stephen, the first Christian Martyr, which is also in Jerusalem. There are many ancient basilicas which were built on the place where a saint was buried. In Rome there are many basilicas like this, because Rome was a very big city, with many Christian people. The Emperors thought Christianity was dangerous to them, because Christians put the rules of Jesus before the law of the Emperor. Many Christians were martyred. When Christianity became legal, churches were built over the graves of martyrs. These churches often became known as basilicas, because they were in the shape of a Roman basilica. Basilicas built over tombs of martyrs include Sant'Agnese outside the Walls, San Lorenzo outside the Walls, and St. Paul's outside the Walls. The words "outside the walls" mean that the burial place of the saint was outside the walls of the city.

Relics
Some basilicas are famous because they have "relics" (or bones or perhaps a body part) of a saint. It could also be the case that the relics were reinterred from the original place.  If a church housed the body of an important saint, then many people would come on pilgrimage and would dedicate themselves to prayer and the use of the sacraments. Basilicas that have bodies include St. Mark's, Venice, St. Nicholas of Bari, also in Italy, and the Basilica of St. Mary Magdalene in Vezelay, France. Not all relics are bodies. Basilicas may also hold a famous object like a piece of the True Cross, or the belt worn by the Virgin Mary. People often ask whether all these precious relics are authentic. The Roman Catholic Church does not get into arguments about trying to prove whether the pieces of the Cross, the body parts and other things are real. Sometimes the relic is known to be real. Sometimes there is no way to prove it, either way.

Saints
Other basilicas are churches that were built by a famous saint, were used by a famous saint, or were built to honour the saint, who did not die as a martyr but lived a very holy life. Two of the most famous basilicas of this sort are the Basilica of St. Francis of Assisi and the Basilica of St. Anthony of Padua. Many thousands of pilgrims go to these churches every day to remember two saints who were gentle, humble and taught people to live better lives.

Signs and Miracles
Some basilicas are built because a miracle or special sign took place. The sign might be a vision and might give a plan to build.  The Basilica of Lourdes in France is built at the place where Bernadette Soubirous had a vision of the Virgin Mary. It is an important pilgrimage place.  Sometimes the sign is not so strange as a vision. In the Philippines, the Basilica del Santo Niño was built at the place where a partly burnt box was found in 1565. It contained a little statue of the Christ Child and had been left behind by some Spanish or Portuguese explorers many years earlier. "Santo Niño" means "Holy Child" in Spanish.

Well-known basilicas

Major basilicas
The four great Basilicas of Rome, as well as having a seat and an altar for the pope, have a Holy Door which is only opened for special occasions such as a Jubilee Year.
 The Basilica of St. John Lateran, is also called the Lateran Basilica. It is the cathedral of the Bishop of Rome, the Pope.
 St. Peter's Basilica, also called the Vatican Basilica, is a major pilgrimage site, being built over the burial place of Saint Peter. It is used for most of the main religious ceremonies in which the Pope takes part.
 The Basilica of St. Paul outside the Walls, is also known as the Ostian Basilica, because it is on the road that led to Ostia. It is built over the burial place of Saint Paul.
 The Basilica of Santa Maria Maggiore, (St. Mary Major) is also called the Liberian basilica, because the building was thought to have been built by Pope Liberius. It is the largest church in Rome dedicated to the Virgin Mary.

Other well-known basilicas

 The Church of the Holy Sepulchre, Jerusalem, Israel
 The Basilica of St. Nicholas of Bari in Bari, Italy
 The Basilica of St. Anthony of Padua in Padua, Italy
 The Basilica of St. Francis of Assisi in Italy
 The Basilica of St. Mark in Venice, Italy
 The Basilica of St. Denis, near Paris, France
 The Basilica of St. Louis, St. Louis, Missouri USA
 The Basilica of Our Lady of Fátima, Portugal
 The Cathedral Basilica of San Thome, Chennai, India
 St. Stephen's Basilica, Budapest, Hungary
 The Cathedral Basilica of St. Chad, Birmingham England(1941)
 The Cathedral Basilica Shrine of Our Lady of the Rosary, Argentina
 The Cathedral Basilica of St. Mary, Help of Christians Sydney, Australia
 The Basilica of Our Lady of Peace of Yamoussoukro, in Côte d'Ivoire West Africa
 The Cathedral Basilica of Notre-Dame de Québec in Quebec City was the first basilica in North America. (1874).
 The Cathedral Basilica of Our Lord Jesus Christ King of the Universe, Reykjavík, Iceland
 The Basilica of St. Adalbert in Buffalo, New York United States of America, (1907)
 The Cathedral Basilica of Las Lajas, in Colombia
 Berchem Basilica, Antwerp, Belgium (1878)
 San Francisco de la Habana Basilica in Havana, Cuba
 The Basilica of St. Gereon, Cologne, Germany (1920)
 The Basilica of Our Lady of Lanka, Tewatte, Sri Lanka
 The Basilica of San Isidoro , León, Spain
 The Basilica of the Black Nazarene, Philippines
 The Basilica of Emmaus Nicopolis, Israel
 The Basilica of la Sagrada Familia, Spain, has been under construction since 1882, and although it is still unfinished, it was consecrated and proclaimed a minor basilica by Pope Benedict XVI in November 2010

Gallery

Related pages
 Church
 Cathedral
 Chapel
 Christianity
 Roman Catholicism

References

 Architecture of the basilica, well illustrated.
 Basilica Porcia
 W. Thayer, "Basilicas of Ancient Rome": from Samuel Ball Platner (as completed and revised by Thomas Ashby), 1929. A Topographical Dictionary of Ancient Rome (London: Oxford University Press)
 Paul Veyne, ed. A History of Private Life I: From Pagan Rome to Byzantium, 1987
 List of All Major, Patriarchal and Minor Basilicas by Giga-Catholic Information
 Catholic Encyclopedia: Basilica & minor parts in other articles
 Richard Krautheimer, Early Christian and Byzantine Architecture
 Domus ecclesiae: Privileges and obligations pertaining to minor basilicas
Church architecture
Roman buildings and structures

Basilica


Yahudi (Hebrew: יַהֲדוּת Yahăḏūṯ) ek rakam ke dharm hae, 14–15 million million Yahudi dunia mein hae.

Duusra websites
 A large website for Jewish people
 The Jewish History Resource Center Project of the Dinur Center for Research in Jewish History, The Hebrew University of Jerusalem
 Judaism article from the 1901-1906 Jewish Encyclopedia
 The Jewish Virtual Library
 Orthodox Judaism - The Orthodox Union: Official website
 The United Synagogues of Conservative Judaism: Official website
 Askmoses.com: Orthodox Judaism site that explains a lot of the basics of Judaism.
 Jewish Reconstructionist Federation: Official website
 The Judaica Press Complete Tanach with Rashi in English
 Global Directory of Jewish Museums
 Torah.org. (also known as Project Genesis) Contains Torah commentaries and studies of Tanakh, along with Jewish ethics, philosophy, holidays and other classes.
 The complete formatted Talmud online. Interpretative videos for each page from an Orthodox viewpoint are provided in French, English, Yiddish and Hebrew.

Dharam

Yahudi


In physics, interference is the effect of wave functions. A single wave can interfere with itself, but this is still an addition of two waves (see Young's slits experiment). Two waves always interfere, even if the result of the addition is complicated or not remarkable.

Something that happens when two or more waves are in the same space. Sometimes the peak of one wave joins with the peak of another wave, so the resulting peak is twice as high. Sometimes the peak of one wave falls into the trough of another wave, and the surface is then flat. When waves add their effects, it is called positive interference, or constructive interference. When one wave subtracts from the effects of the other, it is called negative interference, or destructive interference.

If two people pushed on a car in the same direction, they would move the car better than either one alone. That would be positive interference.  If two people of equal strength pushed the car from opposite directions, then it would not be moved by either of them. That would be negative interference.

Constructive interference

Constructive interference happens when two or more waves are in the same space and in phase. When this happens, the waves' amplitudes add together and the total is greater than the amplitude of any of the waves by themselves. This causes the waves to appear more intense.

At time = 0, one wave top is moving from the left and another wave is moving from the right.
At time = 1, the two wave tops meet in the middle.
At time = 2, the two waves have each continued moving forward and reappear again at their original heights.

Destructive interference
Destructive interference happens when two or more waves are in the same place and out of phase. When this happens, the waves' amplitudes add together and the total is less than the amplitude of any of the waves by themselves. This causes the waves to appear less intense.

At time = 0, a wave top is moving in from the left and a wave trough is moving in from the right.
At time = 1, the two waves have met in the middle. The crest (top) fills in the trough.
At time = 2, the two waves have moved along in their original direct and each reappears.

Examples of interference
After a rain, one can often see patterns when a little oil floats on top of puddles. The colors will be in the order: red, orange, yellow, green, blue, and violet. Each of these colors of light has its own wavelength, and different parts of the oil have different thicknesses. Part of the light from the sun bounces off the top surface,  in other words it bounces off the oil. Part of the sunlight bounces off the top of the water. The light waves from the oil surface and the light from the water surface meet back in the air, and they interfere. For any thickness of the oil layer, some of the light waves will add and some will subtract, so the result is that one color of light will be strongest there.

When two highly polished sheets of glass are pressed together, sometimes the distance between the two pieces will change from place to place. When that happens, the pattern that shows up is called "Newton's rings." When slide photographs are put between two thin sheets of glass for showing in a slide projector, this kind of pattern is a big problem. The same problem can show up when two microscope slides are put together.

Noise-canceling headphones use destructive interference to cut out noise from the outside.

Physics questions

Here is a diagram of the kind of thing that produces some kinds of light interference. The distance between the top piece of glass and the bottom piece gets larger near the outside edges.

A simpler setup would be to have two flat pieces of glass in contact along one edge and a narrow angle between their two faces. If the separation between the top surface of the first piece of glass and the top surface of the second piece of glass is, at some point, such that light beams reflected from each are synchronized or in phase, then the reflected light will be bright, but if the two beams are half a cycle out of phase, then at that point the two beams will cancel each other and what reflected light there is will not be bright.

Wave physics

Interference


Births
 April 6 – Wilbur Wright
 April 9 – Chris Watson, 3rd Prime Minister of Australia (d. 1941)
 November 7 – Marie Curie, Polish-French chemist and physicist (d. 1934)

Deaths
 January 14 – Jean Auguste Ingres, French painter (b. 1780)
 January 30 – Emperor Komei of Japan (b. 1831)
 May 12 – Friedrich William Eduard Gerhard, German archaeologist (b. 1795)
 June 19 – Maximilian, Emperor of Mexico (executed) (b. 1832)
 August 25 – Michael Faraday, English chemist and physicist (b. 1791)
 August 31 – Charles Baudelaire, French writer (b. 1821)
 September 10 – Simon Sechter, Austrian music teacher (b. 1788)
 Alexander Bryan Johnson, American philosopher (b. 1786)

Events
 January 1 – The John A. Roebling Suspension Bridge opens between Cincinnati, Ohio and Covington, Kentucky, becoming the longest suspension bridge in the world
 January 8 – African-American men are granted the right to vote in the District of Columbia.
 January 11 – Benito Juárez becomes Mexican president again
 January 30 – Emperor Komei of Japan dies. Crown Prince Mutsuhito is expected to become the next Emperor of Japan.
 January 31 – Maronite nationalist leader Karam leaves Lebanon on board of a French ship for Algeria
 February 3 – Shogun Tokugawa Yoshinobu abdicates, and the late Emperor Komei's son, Prince Mutshuhito becomes Emperor Meiji of Japan. End of the Late Tokugawa shogunate.
 February 17 – The first ship passes through the Suez Canal
 March 1 – Nebraska is admitted as the 37th U.S. state.
 March 16 – First publication of an article by Joseph Lister outlining the discovery of antiseptic surgery, in The Lancet.
 March 29 – The British North America Act receives royal assent, forming the Dominion of Canada in an event known as Confederation. This unites the Province of Canada, Quebec, Ontario, New Brunswick, and Nova Scotia as of July 1. Ottawa becomes the capital, and John A. Macdonald becomes the Dominion's first prime minister.
 March 30 – Alaska is purchased for $7.2 million from Alexander II of Russia, about 2 cent/acre ($4.19/km2), by United States Secretary of State William H. Seward. The news media call this "Seward's Folly."
 April 1 – Strait Settlement of Singapore, formerly ruled from Calcutta, becomes a Crown Colony under the jurisdiction of the Colonial Office in London.
 April 24 - A very bad earthquake hits Manhattan, Kansas.
 May 29 – Austro-Hungarian agreement called Ausgleich ("the Compromise") is born through Act 12, which established the Austro-Hungarian Empire; on June 8 Emperor Franz Joseph I was crowned King of Hungary
 June 19 – Firing squad executes Emperor Maximilian I of Mexico
 July 1 – Canada Day, recognizing the creation of Canada by the British North America Act.
 July 17 – In Boston, Massachusetts, the Harvard School of Dental Medicine is established as the first dental school in the United States.
 July 21 – Missionary Thomas Baker killed and eaten in Viti Levu, Fiji
 September 2 – Mutsuhito, the Meiji Emperor of Japan marries Ichijo Masako. The Empress consort is thereafter known as Lady Haruko.
 September 30 – The United States takes control of Midway Island.
 October 21 – 'Manifest Destiny': Medicine Lodge Treaty – Near Medicine Lodge Creek, Kansas a landmark treaty is signed by southern Great Plains Indian leaders. The treaty requires Native American Plains tribes to relocate a reservation in western Oklahoma.
 October 27 – Giuseppe Garibaldi's troops march into Rome
 December 2 – In a New York City theater, British writer Charles Dickens gives his first public reading in the United States.
 December 4 – Former Minnesota farmer Oliver Hudson Kelley founds the Order of the Patrons of Husbandry (better known today as the Grange movement).

1867


The Alps (, , , , , , ) is the greatest mountain range of Europe. It reaches from Austria and Slovenia in the east; through Italy, Switzerland, Liechtenstein and Germany; to France in the west. The original meaning of the word was 'white'.

The highest mountain in the Alps is Mont Blanc, at , on the Italian–French border.

Geography

The Alps stretch from Austria and Slovenia in the east, through Italy, Switzerland, Liechtenstein and Germany to France in the west.

Division
The mountains are divided into the Western Alps and the Eastern Alps. The division is along the line between Lake Constance and Lake Como, following the Rhine (on the north side, in Switzerland) and the river Mera in the South (in Italy). The Western Alps are higher, but their central chain is shorter and curved; they are located in Italy, France and Switzerland.

The Eastern Alps (main ridge system elongated and broad) belong to Austria, Germany, Italy, Liechtenstein, Slovenia and Switzerland.

The highest peaks of the Western Alps are Mont Blanc, 4,808 metres (15,774 ft), Mont Blanc de Courmayeur 4,748 metres (15,577 ft), the Dufourspitze 4,634 metres (15,203 ft) and the other summits of the Monte Rosa group, and the Dom, 4,545 metres (14,911 ft). The highest peak in the Eastern Alps is Piz Bernina, 4,049 metres (13,284 ft). Perhaps the most famous location for tourist to the Alps are the Swiss Alps.

Main chain

The main chain of the Alps follows the watershed from the Mediterranean Sea to the Wienerwald, Austria, defining partially the northern border of Italy. It then passes over many of the highest and most famous peaks in the Alps. From the Colle di Cadibona to Col de Tende it runs to the west before turning to the northwest and then, to the north, near the Colle della Maddalena. Upon reaching the Swiss border, the line of the main chain goes about northeast, a heading it follows until its end near Vienna.

Four-thousanders
The Union Internationale des Associations d'Alpinisme (UIAA) has defined a list of 82 "official" Alpine 4,000-meter (13,123 ft) peaks. The list has many sub-peaks with little prominence, but good for mountaineering. Here are the twelve four-thousanders with at least 1 km prominence.

Alpinisme
Karl Blodig was the first person to climb all the main four-thousand meter peaks, round 1900.

The Alpine Club is the oldest organization of mountaineers of the world. It's an organization from Great Britain, formed in 1857.

The Swiss Alpine Club was founded in 1863.

Geology and orogeny
The reason mountains form is usually the moving together of continental plates of the Earth's crust. The Alps rose as a result of the slow but gigantic pressure of the African plate as it moved north against the stable Eurasian landmass. In particular, Italy (which had been a separate island) got pushed into Europe.

This all took place in the Tertiary period, mostly in the Miocene and Pliocene. That's about 35 to 5 million years ago.

The Alps are just a part of a larger orogenic belt of mountain chains, called the Alpide belt. It reaches through southern Europe and Asia from the Atlantic Ocean most of the way to the Himalayas.

A gap in these mountain chains in central Europe separates the Alps from the Carpathians off to the east. Subsidence is the cause of the gaps in between.

A great and ancient ocean was once between Africa and Europe, the Tethys Ocean. Now sediments of the Tethys Ocean basin and its Mesozoic and early Cenozoic strata sit high above sea level. Even metamorphic basement rocks are found high on Mont Blanc, the Matterhorn, and other high peaks in the Pennine Alps and Hohe Tauern.

The formation of the Mediterranean Sea is a more recent development.

Transport
The Alps do not make an impassable block; the common passes have been traveled by since the ancient history for war and commerce, and later by pilgrims, students and tourists.
Mountain passes give paths between mountains, for road, train or foot traffic.  Some are famous, being used for thousands of years.

Important passes in the Alps are, e.g.:

 Mont Cenis
 Little St Bernard Pass
 Great St Bernard Pass
 Simplon Pass
 Furka Pass
 Gotthard Pass
 Julier Pass
 Arlberg
 Bernina Pass
 Brenner Pass

Long highway and railway tunnels:

 Fréjus Rail Tunnel
 Mont Blanc Tunnel
 Simplon Tunnel
 Gotthard Base Tunnel (the longest railway tunnel of the world)
 Gotthard Road Tunnel
 Arlberg Railway Tunnel

Bridges:
 Teufelsbrücke (devil's bridge)

Travel and visitors

The Alps are popular both in summer and in winter. The Alps as a place for sightseeing and sports. Winter sports (Alpine and Nordic skiing, snowboarding, tobogganing, snowshoeing, ski tours) can be learned in most regions from December to April. In summer, the Alps are popular with hikers, mountain bikers, paragliders, and mountaineers. There are also alpine lakes which attract swimmers, sailors and surfers. The lower places and bigger towns of the Alps are well served by motorways and main roads, but higher passes and by-roads can be bad even in the summer. Many passes are closed in winter. Many airports around the Alps (and some within), as well as long-distance rail links from all bordering countries, afford large numbers of travelers easy access from abroad. The Alps normally has more than 100 million visitors a year.

Climate
The Alps is split into five climate zones, each with a different kind of environment. The climate, plant life and animal life vary on different sections or zones of the mountain.

 The section of the Alps that is above 3,000 metres is called the névé zone.  This area, which has the coldest climate, is permanently coated with compressed snow.  Plants are therefore scarce in the névé zone.
 The alpine zone lies between the height of 2,000 and 3,000 metres.  This zone is less cold than in the névé zone.  Wildflowers and grasses grow here.
 Just below the alpine zone is the subalpine zone, 1,500 to 2,000 metres high.  Forests of fir trees and spruce trees grow in the subalpine zone as the temperature slowly goes up.
 At about 1,000 to 1,500 metres high is the arable zone.  Millions of oak trees sprout in this area.  This is also where farming takes place.
 Below 1,000 metres are the lowlands.  Here, a larger variety of plants are produced. Aside from plants, villages are also in the lowlands because the temperature is easier for humans and farm animals.

The Alps is a classic example of what happens when a temperate area at lower altitude gives way to higher land. A rise from sea level into the upper regions causes the temperature to decrease. The effect of mountain chains on winds is to carry warm air belonging to the lower region into an upper zone, where it expands and loses heat, and drops snow or rain.

Plants
The typical trees—oak, beech, ash and sycamore maple have a natural height limit: the 'tree line'. Their upper limit matches the change in climate which comes with increasing height. The change from a temperate to a colder climate is also shown true by a change in the wild flowering plant life. This limit normally lies about  above the sea on the north side of the Alps. On the southern slopes, it often reaches to , sometimes even to .

The Alps do not always have the typical trees. People have felled them in many places. Except for the beech forests of the Austrian Alps, forests of the typical deciduous trees are hardly found. Where such woods were, Scots pine and Norway spruce now grow. These trees are less sensitive to the attacks of goats who eat the saplings of deciduous trees.

Above the tree line, there is often a band of dwarf pine trees (Pinus mugo), which is taking place of dwarf shrubs. These shrubs are Rhododendron ferrugineum (on acid soils) or Rhododendron hirsutum (on non-acid soils).

Above this is the alpine meadow. Above the alpine meadow is where plant life becomes less and less common. At these great heights, the plants are likely to make separate groups. In the Alps, many species of flowering plants have been recorded above . These are like Ranunculus glacialis, Androsace alpina and Saxifraga biflora.

Animals
Species common to the Alps:

References

Alps


Theodosius Grygorovych Dobzhansky (; ; January 25, 1900 – December 18, 1975) was a noted geneticist and an evolutionary biologist.

Dobzhansky was born in Ukraine (then part of Imperial Russia) and emigrated to the United States in 1927. He was a central figure in the field of evolutionary biology for his work on the fruit-fly Drosophila. He did research on these flies in California, mostly on populations of Drosophila pseudoobscura.

Dobzhansky was important in the modern evolutionary synthesis, which was the synthesis of evolutionary biology with genetics.

Ukraine and Russia
At school Dobzhansky collected butterflies and beetles, and studied biology at Kiev University. After graduation he moved to St Petersburg (then called Leningrad), and studied under Yuri Filipchenko, who had a Drosophila lab. Dobzhansky collected Coccinellidae (ladybird beetles) in the wild, and explored their genetics.

America
Dobzhansky emigrated to the United States in 1927. He worked with Thomas Hunt Morgan at Columbia University, who had pioneered the use of fruit flies (Drosophila melanogaster) in genetics experiments. He followed Morgan to the California Institute of Technology from 1930 to 1940. Dobzhansky took fruit fly research out of the laboratory and into the field. He discovered that regional varieties of flies were more similar to each other genetically than to flies from other regions.

In 1937 Dobzhansky published one of the major works of the modern evolutionary synthesis, entitled Genetics and the Origin of Species. He defined evolution as "a change in the allele frequency within a gene pool". It is through changes in the proportion of alleles in a population that evolution takes place. Also in 1937, he became a naturalized citizen of the United States. During this time he had a falling out with one of his Drosophila collaborators, Alfred Sturtevant, based perhaps on professional competition.

Dobzhansky returned to Columbia University from 1940 to 1962. He was one of the signatories of the 1950 UNESCO statement The Race Question. He then moved to the Rockefeller University) until his retirement in 1971.

Other key publications
 Nothing in biology makes sense except in the light of evolution  The American Biology Teacher 35: (March): 125-129.
 Genetics of the evolutionary process. Columbia University Press, New York 1970.
 Dobzhansky's Genetics of Natural Populations I-XLIII. R.C. Lewontin, J.A. Moore, W.B. Provine & B. Wallace, eds. Columbia University Press, New York 1981. (reprints the 43 papers in this series, all but two of which were authored or co-authored by Dobzhansky)

References

1900 births
1975 deaths
American evolutionary biologists
American zoologists
Ukrainian scientists
American geneticists
Naturalized citizens of the United States
Rockefeller University faculty
Columbia University faculty
California Institute of Technology faculty

Theodosius Dobzhansky


Sapote (from Nahuatl tzapotl) is a word for a soft, edible fruit. The word is part of the names of several plants from Mexico, Central America and northern parts of South America that have fruits.

Some but not all sapotes come from the family Sapotaceae:

 Sapotaceae sapotes:
 Sapodilla (Manilkara zapota) is native to Mexico, Guatemala, Nicaragua, Belize, and possibly El Salvador.
 Yellow sapote (Pouteria campechiana) is from Mexico and Central America.
 Mamey sapote (Pouteria sapota) is from southern Mexico to northern South America.
 Green sapote (Pouteria viridis) is native to lowland southern Mexico.

 Ebenaceae sapotes:
 Black sapote (Diospyros digyna) is from eastern Mexico south to Colombia. This is probably the original Aztec tzapotl.
 Chapote (Diospyros texana) is from the lower Rio Grande valley region in Texas and Mexico

 Other sapotes
 White sapote (Casimiroa edulis: Rutaceae) is from northern and central Mexico, Costa Rica, El Salvador and Guatemala.
 South American sapote (Quararibea cordata: Malvaceae) is from the Amazon rainforests of Brazil, Colombia, Ecuador, and Peru.

References

Tropical fruit

Sapote


Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. It combines aspects of inorganic chemistry (the study of non-carbon bonds) and organic chemistry (the study of carbon bonds).

Examples of organometallic compounds are tetraethyllead; it was used as a fuel (leaded gasoline) additive in the past. Also Methylcobalamin (Vitamin B12) is a common organometallic compound.

Organometallic compounds

Organometallic compounds are compounds that have chemical bonds between an one or more metal atoms and one or more carbon atoms of an organyl group (an organic ligand). They have the prefix "organo-" (for example, organopalladium compounds). Organometallic compounds include subgroups like the metalloproteins such as haemoglobin.

The term "metalorganics" usually refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands which bind them to an organic compound. Metal beta-diketonates, alkoxides, and dialkylamides are members of this class.

In addition to the traditional metals, elements such as boron, silicon, arsenic, and selenium form organometallic compounds.

Coordination compounds with organic ligands

Many complexes have coordination bonds between a metal and organic ligands. The organic ligands often bind the metal through a heteroatom such as oxygen or nitrogen, in which case such compounds are called "coordination compounds".

Many organic coordination compounds occur in nature. For example, hemoglobin and myoglobin contain an iron center coordinated to the nitrogen atoms of a porphyrin ring; magnesium is the center of a chlorin ring in chlorophyll. The field of such inorganic compounds is known as bioinorganic chemistry. However, methylcobalamin (a form of Vitamin B12), with a cobalt-methyl bond, is a true organometallic complex, one of the few known in biology.

Structure and properties
The metal-carbon bond in organometallic compounds is half way between being ionic and covalent. Organometallic compounds with bonds that have characters in between ionic and covalent are very important in industry. They are both relatively stable in solutions but ionic enough to undergo reactions. Two important classes are organolithium and Grignard reagents.

Uses
Organometallics find practical uses in stoichiometric and catalytic processes, especially processes involving carbon monoxide and alkene-derived polymers.  All the world's polyethylene and polypropylene are produced with organometallic catalysts.  Acetic acid is produced using metal carbonyl catalysts in the Monsanto process and Cativa process. The bulk of the synthetic alcohols, at least those larger than ethanol, are produced by hydrogenation of hydroformylation-derived aldehydes.  Similarly, the Wacker process is used in the oxidation of ethylene to acetaldehyde.

Organomettalic are highly basic and highly reducing. They catalyze many polymerization reactions. They are also useful stoichiometrically.

Organometallic compounds may be found in the environment. Environmentalists worry about organo-lead and organo-mercury compounds. They are toxic hazards.

Research is currently underway using organometallic catalysis.  The energy crisis has initiated increased interest in more efficient ways of working with the remaining fossil fuels we have left.  While many agree that lowering oil dependence is safer for the environment as well as politically wise.   The new interest in "green" technologies has also helped increase research.  Many examples of organometallic research can be found in the petrochemical and pharmaceutical industries.  Some current methods of chemical production are wasteful and produce toxic waste, while many organometallic catalysts show promise to change that.

History
Louis Claude Cadet synthesized methyl arsenic compounds related to cacodyl. William Christopher Zeise made platinum-ethylene complex. Edward Frankland discovered dimethyl zinc. Ludwig Mond discovered Ni(CO)4. Victor Grignard worked with organomagnesium compounds. The abundant and diverse products from coal and petroleum led to Ziegler-Natta, Fischer-Tropsch, hydroformylation catalysis which employ CO, H2, and alkenes as feedstocks and ligands.

Years ago, Tetraethyllead was added to gasoline as an antiknock agent. Because lead is toxic, it is no longer used in gasoline. Instead, other organometallic compounds such as ferrocene and methylcyclopentadienyl manganese tricarbonyl (MMT) are now added to gasoline to prevent knocking.

The 1973 Nobel Prizes to Ernst Fischer and Geoffrey Wilkinson for work on metallocenes made organometallic chemistry more popular. In 2005, Yves Chauvin, Robert H. Grubbs and Richard R. Schrock shared the Nobel Prize for metal-catalyzed olefin metathesis.

Organometallic chemistry timeline
 1760 Louis Claude Cadet de Gassicourt investigates inks based on Cobalt salts and isolates Cacodyl from cobalt mineral containing arsenic
 1827 Zeise's salt is the first platinum / olefin complex
 1848 Edward Frankland discovers diethylzinc
 1863 Charles Friedel and James Crafts prepare organochlorosilanes
 1890 Ludwig Mond discovers Nickel carbonyl
 1899 Introduction of Grignard reaction
 1900 Paul Sabatier works on hydrogenation organic compounds with metal catalysts. Hydrogenation of fats kicks off advances in food industry, see margarine
 1909 Paul Ehrlich introduces Salvarsan for the treatment of syphilis, an early arsenic based organometallic compound
 1912 Nobel Prize Victor Grignard and Paul Sabatier
 1930 Henry Gilman works on lithium cuprates, see Gilman reagent
 1951 Ferrocene is discovered
 1963 Nobel prize for Karl Ziegler and Giulio Natta on Ziegler-Natta catalyst
 1965 Discovery of cyclobutadieneiron tricarbonyl
 1968 Heck reaction
 1973 Nobel prize Geoffrey Wilkinson and Ernst Otto Fischer on sandwich compounds
 1981 Nobel prize Roald Hoffmann and Kenichi Fukui on Isolobal Principle
 2005 Nobel prize Yves Chauvin, Robert Grubbs, and Richard R. Schrock on metal-catalyzed alkene metathesis
 2010 Nobel prize Richard F. Heck, Ei-ichi Negishi, Akira Suzuki for their work in palladium-catalyzed coupling reactions in organic synthesis.

Related pages
Chelation

References

Other websites
 MIT OpenCourseWare: Organometallic Chemistry
 Rob Toreki's Organometallic HyperTextbook
  Web listing of US chemists who specialize in organometallic chemistry

Organometallic chemistry


A subatomic particle is a particle smaller than an atom. This means it is very, very small.  Like atoms and molecules, a subatomic particle is far too small to be seen with the eye.  They are also very interesting to physicists who study atoms.  The subatomic particles that make atoms: protons, neutrons, and electrons are the most commonly studied ones.  The study of subatomic particles is called particle physics.

These particles are often held together within an atom by one of the four fundamental forces (gravity, electromagnetic force, strong force, or weak force).  Outside of the atom the particles often move very, very quickly- near the speed of light which is very, very fast (around 300,000 kilometres per second).

Subatomic particles are divided into two groups, Baryons and Leptons.

Baryons are made of quarks while Leptons are thought to be among the smallest particles, called elementary particles. Baryons have a given Baryon number. In reactions, the Baryon number must be conserved, meaning that both the starting and ending sides of a reaction must have the same number of Baryons. Baryonic particles are made up of a combination of 3 of the six quarks, which are among the smallest particles. The six quark types are up, down (making up protons and neutrons), strange, charm, top, and bottom.

Leptons are generally much smaller than Baryons. This category includes electrons, Muons, Taus and neutrinos. Leptons are not made up of quarks and are not divisible.

For every one of these types, there is also an antiparticle. Antiparticles have the same mass as their normal counterparts, except they have the opposite electric charge. Anti-matter and matter cannot exist near each other. Whenever matter and antimatter collide, they destroy each other with a huge release of energy equivalent to E=mc2, where m is the combined mass of the particles, c is the speed of light, and E is the energy produced. These collisions often take place in large particle accelerators, where the energy can be converted the other way, into matter by the same equation. This can produce many odd, often heavy (large mass) particles that exist only for a short time.

Most of the particles discovered are created by accelerating particles and colliding them against others, creating huge showers of new subatomic particles which decay extremely quickly. However, because the particles are moving close to the speed of light, the laws of special relativity become important and time dilation occurs. This means that time passes slower for the particle, and they can travel (and be measured) over a longer distance than non-relativity science would predict.

Subatomic particle


The didgeridoo (sometimes didjeridu) is an Australian Aboriginal wind musical instrument. They were used by the Yolgnu people of Arnhem Land. They can be quite long, anywhere from  long. Most are around   long. The longer the instrument, the lower the pitch or key of the instrument. They are a  hollow wooden tube, which can be either cylindrical or conical in shape. It is best described as being a wooden trumpet or drone. Musicologists say it is a brass aerophone.

It is difficult to know when didgeridoos were first used. Studies of rock art in Arnhem Land show that it has been in use for more than 1,500 years. A  rock painting in Ginga Wardelirrhmeng, on the northern edge of the Arnhem Land plateau, dates from the freshwater period. It shows a didgeridoo player and two singers playing in a ceremony.

The word
"Didgeridoo" is said to be a word invented in the West, not an Aboriginal word. It may come from the Irish words dúdaire or dúidire. This means 'trumpeter; constant smoker, puffer; long-necked person, eavesdropper; hummer, crooner' and  dubh, meaning "black" (or duth, meaning "native").  However, this theory is not widely accepted.

The earliest examples of the word in print was in a 1919 issue of Smith's Weekly where it was called an "infernal didjerry" which "produced but one sound - (which sounded like) didjerry, didjerry, didjerry and so on". It was also used the 1919 Australian National Dictionary, The Bulletin in 1924 and the writings of Herbert Basedow in 1926.  There are more than 45 names for this instrument among the Aboriginal people of northern Australia including Yirdaki. Yirdaki, also sometimes spelt yidaki, is for the instrument made and used by the Yolngu people of north-east Arnhem Land.

Making a didgeridoo

Aboriginal didgeridoos are made in the traditional communities in Northern Australia or by makers who travel to Central and Northern Australia to get the materials. They are usually made from hardwoods, usually eucalyptus species that are native to the area. Sometimes a native bamboo, such as Bambusa arnhemica, or pandanus is used. The main trunk of the tree is used, though a big branch may be used instead. Aboriginal makers spend a lot of time looking for a tree that has been hollowed out by termites. If the hollow is too big or too small, it will make a poor quality instrument.

When a tree is found and cut down, the part of trunk or branch that will be made into a didgeridoo is cut out. The bark is taken off, the ends are trimmed, and there is some shaping of the outside. It may be painted or left natural. A rim of beeswax may be put on to the mouthpiece end. Traditional instruments made by Aboriginals in Arnhem Land are sometimes fitted with a 'sugarbag'  mouthpiece. This is black beeswax from wild bees and has a its own special smell.

Didgeridoos can also be made from PVC pipes, non-native hard woods (which are split, hollowed and rejoined), fiberglass, metal, agave, clay, hemp (a bioplastic named zelfo), and even carbon fiber. These didgeridoos usually have an upper inside diameter of around 1.25" down to a bell end of anywhere between two to eight inches and have a length made to the needed key. The mouthpiece can be made of beeswax, hardwood or simply sanded and sized by the craftsman. In PVC, rubber stopper with a hole cut into it can be used.

Modern didgeridoo designs are different from the traditional Australian Aboriginal didgeridoo. They are recognized as being a separate instrument. Didgeridoo design changes started in the late 20th century using new materials and different shapes.

Playing the didgeridoo

A didgeridoo is usually played sitting down because they are so long. It is played with continuously vibrating lips to make the drone while using a special way of breathing called circular breathing. This means a player breathes in through the nose at the same time as pushing air out of the mouth. A skilled player can refill the air in their lungs. With practice, the player can keep a note playing for as long as desired. There are recordings of modern didgeridoo players playing without stopping for more than 40 minutes; Mark Atkins on Didgeridoo Concerto (1994) plays for over 50 minutes continuously.

The rhythm of the circular breathing, gives the instrument its readily recognizable sound. Other changes in the didgeridoo's sound can be made by adding vocal sounds to the drone. Most of the sounds are related to the sounds of Australian animals, such as the dingo or the kookaburra. To make these sounds, the players simply have to use their voice to make the sounds of the animals whilst continuing to blow air through the instrument. The results range from very high-pitched sounds to very low sounds. Adding vocal sounds increases the complexity of the playing.

Anthony Baines wrote that the didgeridoo is like "...an aural kaleidoscope of timbres". He also said that the virtuoso skills used by the best performers were unlike those needed on any other instrument.

Use of the didgeridoo
The didgeridoo was mainly played for ceremonial dancing and singing. It was also common for didgeridoos to be played for entertainment outside of ceremonial life. In northern Australia, the didgeridoo is still a very important as it plays for singers and dancers in surviving cultural ceremonies. Today, most didgeridoo playing is for entertainment in both Indigenous Australian communities and elsewhere around the world.

Pair sticks, sometimes called clapsticks or bilma, set the beat for the songs during ceremonies. The rhythm of the didgeridoo and the beat of the clapsticks use patterns that have been handed down for many generations. Traditionally, only men play the didgeridoo and sing during ceremonies, but both men and women may dance. There were female didgeridoo players, but they did not play in ceremonies and it was not encouraged. Linda Barwick, an ethnomusicologist, says that traditionally women have not played the didgeridoo in ceremony, but in informal situations there is no prohibition in the Dreaming Law. On September 3, 2008, the publisher Harper Collins issued a public apology for its book "The Daring Book for Girls", scheduled to be published in October, which openly encouraged girls to play the instrument.

Didgeridoo in popular culture

The didgeridoo is now often used as an instrument in the experimental and avant-garde music scene. Industrial music bands like Test Department- used sounds from this instrument in their performances, linking ecology to industry, influenced by ethnic music and culture.

It has also been an instrument used for the fusion of tribal rhythms with a black metal sound. A music project called Naakhum  used the paganism of the Australian tribes and many others as an approach.

Souvenir didgeridoos
Most didgeridoos made today are for souvenir purposes. It is common to find didgeridoos made of non-native timbers, decorated incorrectly by non-indigenous artists with colourful designs or copied dot patterns. These decorations do not use traditional dreamtime stories or designs. These didgeridoos also often vary widely in size and shape, many being thinner and straighter. As a result of the inadequate wood types, shapes and lengths, souvenir didgeridoos can rarely be used as musical instruments.

Decoration of souvenir didgeridoos is often seen by Aboriginal communities as offensive, inappropriate, inadequate, inaccurate and in many cases, misleading.  The copying of traditional artwork is also used to sell these didgeridoos to unsuspecting tourists.

Health benefits
A 2005 study in the British Medical Journal found that learning and playing the didgeridoo helped reduce snoring and sleep apnea. It does this by making muscles in the upper airway stronger, and this helps them stay open during sleep. This strengthening happens after the player has learned the circular breathing technique.

References

Musical instruments
Indigenous Australian music
Australian music

Didgeridoo


Mollusks are an important phylum of invertebrate animals. Most of them are marine animals, which means they live in the ocean. They have huge numbers in-shore, that is, in shallow water. They are the largest marine phylum, with about 85,000 living species, 23% of all named marine organisms. They also occur in freshwater and on land.

Mollusks are extremely varied: they have great diversity. That may be why there is no word in English for the phylum as a whole. "In an evolutionary sense, mollusks are plastic material". They have much more variety than their ancient rivals, the brachiopods.

Most molluscs have shells, but some groups do not: octopods, slugs, and the gastropods known as sea slugs.

Diversity
Many mollusks also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and in anatomical structure, but also in behaviour and in habitat.

The phylum is usually divided into 9 or 10 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish and octopus, are among the most neurologically advanced of all invertebrates: they have good brains and complex behaviours. Either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods (snails and slugs) are by far the most numerous molluscs in terms of classified species, and account for 80% of the total. The scientific study of mollusks is called malacology.

Main features
The three most universal features defining modern mollusks are:
 a mantle with a cavity used for breathing and excretion,
 the presence of a radula, and
 the structure of the nervous system.

Other than these things, mollusks have so much variety that many textbooks use a "hypothetical ancestral mollusk" to summarize them (see below). This has a single, "limpet-like" shell on top, which is made of proteins and chitin reinforced with calcium carbonate. It is secreted by a mantle covering the whole upper surface. The underside of the animal consists of a single muscular "foot".

The mollusk's feeding system starts with a rasping "tongue", the radula. The complex digestive system uses mucus and microscopic, muscle-powered "hairs" called cilia. The generalized mollusk has two paired nerve cords, or three in bivalves. The brain, in species that have one, circles the oesophagus. Most mollusks have eyes, and all have sensors to detect chemicals, vibrations, and touch. The simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur. All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults.

A striking feature of molluscs is the use of the same organ for multiple functions. For example, the heart and nephridia ("kidneys") are important parts of the reproductive system, as well as the circulatory and excretory systems. In bivalves, the gills both "breathe" and produce a water current in the mantle cavity: this is important for excretion and reproduction. In reproduction, molluscs may change gender to accommodate the other breeding partner.

Good evidence exists for the appearance of gastropods, cephalopods and bivalves in the Cambrian period, 541 to 485.4 million years ago (mya). Before that, the evolutionary history of molluscs' emergence from the ancestral Lophotrochozoa is still unclear.

Mollusk species can also represent hazards or pests for human activities. The bite of the blue-ringed octopus is often fatal, and that of Octopus apollyon causes inflammation that can last for over a month. Stings from a few species of large tropical cone shells can also kill: their venom have become important tools in neurological research. Schistosomiasis (also known as bilharzia, bilharziosis or snail fever) is transmitted to humans via water snail hosts, and affects about 200 million people. Snails and slugs can also be serious agricultural pests, and accidental or deliberate introduction of some snail species into new environments has seriously damaged some ecosystems.

A "generalized mollusk"

Because mollusks have so many different shapes, many textbooks start the subject of molluscan anatomy by describing what is called an archi-mollusc, hypothetical generalized mollusc, or hypothetical ancestral mollusc (HAM) to illustrate the most common features in the phylum. The picture is rather similar to modern monoplacophorans: some think it may resemble very early mollusks.

The generalized mollusk is bilaterally symmetrical and has a single, "limpet-like" shell on top. The shell is secreted by a mantle covering the upper surface. The underside consists of a single muscular "foot". The visceral mass, or visceropallium, is the soft, nonmuscular metabolic region of the mollusc. It contains the body organs.

Taxonomy
Classes of molluscs:
 Aplacophora: molluscs: the living ones are shell-less
 Bivalvia: Most shellfish; clams, oysters, scallops, mussels
 Cephalopoda: Squid, Octopus
 Gastropoda: whelks, limpets, snails, slugs, Nudibranchs
 Helcionelloida: (see below)
 Monoplacophora: molluscs with a cap-like shell
 Polyplacophora: Chitons
 †Rostroconchia: an extinct group
 Scaphopoda: the tusk shells

Helcionelloida
It has become clear that the fossil taxon Helcionelloida does not belong to the class Gastropoda. It is now a separate class in the Mollusca. Parkhaev (2006, 2007) created the class Helcionelloida, whose members were previously treated as "Paleozoic mollusks of uncertain systematic position" by Bouchet & Rocroi.

Uses
 Many mollusks are eaten as food: clams, oysters, scallops, mussels, squid (calamari) and land snails (escargot)
 Oysters sometimes make pearls, which are valuable and used to make necklaces. Other shells are collected for their beauty and sometimes used to make jewelry.

References

Mollusc


Socrates (470 BC – 399 BC) was one of the greatest Greek philosophers. He did not propose any specific knowledge or policy. He showed  how argument, debate, and discussion could help men to understand difficult issues. Most of the issues he dealt with were only political on the surface. Underneath⬇, they were moral questions about how life should be lived. Such is the influence of Socrates that philosophers before him are called the Presocratic philosophers.

Enemies
Socrates made enemies, three of whom brought charges against him. Socrates was tried for his life in 399 BC, found guilty, and put to death by drinking hemlock (a herbal poison). The story of his trial and death is the subject of a tract by Plato which is called the Apologia.

Socrates and Plato
Most of what we know about Socrates comes from the works of Plato, who was his pupil. Socrates lived in the Greek city of Athens. His method of teaching was to have a dialogue with individual students. They would propose some point of view, and Socrates would question them, asking what they meant. He would pretend "I don't know anything; I'm just trying to understand what it is you are saying", or words to that effect. This is now called the Socratic method of teaching.

Reputation
Socrates is sometimes called the "father of Western philosophy". This is because in the discussions he uncovered some of the most basic questions in philosophy, questions which are still discussed today. Some of the people he taught came to be important and successful, like Plato and Alcibiades.

The life of Socrates
Socrates never wrote anything. All of what we know about Socrates is from what other people wrote about him. Our main source of what we know about Socrates is from the writings of his student, Plato. Some of Plato's dialogues, such as the Crito and the Phaedo, are loosely based on fact. They are not written records, but artistic re-creation of Socrates in action.

Another of Socrates' students, Xenophon also wrote about Socrates. Aristophanes, a person who wrote brilliant satirical comedies, wrote about him in play called The Clouds. Socrates was an easy target for satire. He walked barefoot, and with a swagger. Sometimes he stood in a trance for hours.p8 In The Clouds Socrates is a crazy person who tries to scam people out of their money. Plato wrote that Socrates taught for free.

We do not know if Plato's description of Socrates is accurate or not. That is called the 'Socratic problem'. While a lot of what Plato wrote about Socrates is accepted by historians, some believe that Plato (who saw Socrates as a hero) portrayed Socrates as a greater man than he actually was. Some think that Plato was using the character of Socrates as a tool to express his own opinions rather than to accurately write about Socrates. This is what makes Socrates such a mysterious historical figure. Plato's dialogues are works of art, finely written. The general view is that they are based on reality, but no doubt adjusted for the purpose of writing.

Biographical details
Socrates' father was a sculptor, and his mother was a midwife who helped women give birth to children. He may have been a stonemason like his father, and Plato wrote that he served in the Athenian army as a hoplite (heavy infantry). We know he was influenced by an older philosopher, Archelaus, and that he talked with anyone who had interesting ideas in Athens, but beyond that nothing is known.

Socrates was about 50 when he married a much younger woman, Xanthippe. They had three children together. Socrates made complaints about his wife, but no one knew if he was telling the truth.

It is said that one of Socrates' friends went to ask the  oracle at Delphi if there was anyone wiser than Socrates in Athens. The oracle said that there was no wiser person. The oracle was well known for saying things that were ambiguous or unclear. It did not say that Socrates was the wisest, just that there was no person wiser.

After being puzzled by this, Socrates finally decided that his wisdom lay in knowing that he was ignorant. His attempts to show the citizens that some of their ideas were nonsense might help explain his unpopularity. In Plato's works, Socrates says he knows nothing, but can draw out other people's ideas just as his mother helped other women to give birth.

The death of Socrates

The accusations
In 399 BC, when Socrates was an old man, three citizens—Meletus, Anytus and Lycon—brought charges against Socrates. A trial was held. In ancient Athens the procedure was quite different from the present day. There was a jury of 500 men drawn from the citizens. Both the accusers and the defendant had to make speeches in person to the jury. Guilt or innocence was by majority vote. There was no preset penalty if the verdict was 'guilty'. Both the accuser and the defendant would make speeches proposing what the penalty should be. Again, a vote was taken.p17

There were two charges against him. The general theme was that Socrates was a menace to society. The first charge was of heresy, disbelief in the Gods. It was probably meant to cause prejudice amongst the jurymen. Actually, Socrates observed all the correct procedures of the religion of his times. The charge had been used successfully against another philosopher, Anaxagoras.p17

The second charge was that he corrupted the youth with his teachings. What was meant by this? Apparently, this was not about his personal relationship with his pupils. It was about the way he was thought to influence their political views. His circle had included a number of right-wing aristocrats whose ideas were now rejected by most citizens. The brilliant Alcibiades, once a great leader of Athens, was now seen as a traitor.p17

The trial
Crito, a friend of Socrates, illegally paid the prison guards to allow Socrates to escape.  Socrates, however, decided not to escape.  When Socrates was put on trial, he gave a long speech to defend himself against the claims made by the Athens government.

We have Plato's version of how Socrates defended himself, in the Apologia. It starts:
"I do not know what effect my accusers have had upon you, gentlemen, but for my own part I was carried away by them; their arguments were so convincing. On the other hand, scarcely a word of what they said was true".p19

The sentence
When Socrates was asked to propose his punishment, Socrates said that the government should give him free dinners for the rest of his life for all the good that he did for society. The court held a vote between giving Socrates a fine to pay or putting him to death.  The verdict was that Socrates was to be put to death.

Death of Socr

Plato on Socrates' trial and death
There are several dialogues by Plato which deal directly with the trial of Socrates and the period up to his death. They are, in order of the events:
Apologia, or The Apology. This deals in particular with Socrates' defence at his trial. It is regarded as accurate in substance, and perhaps in detail.
Crito. This deals with the month between his trial and his death. In particular, Socrates explains to his friend Crito why he is not going to escape, or permit his friends to bribe the jailor.
Phaedo. This is a later work. It is written as if by an eye-witness of the last day of Socrates' life. In the work, Phaedo of Elias reports to a group of friends on what Socrates said on his last day. This is called a "reported dialogue" or one dialogue inside another.  The Phaedo is longer than the other two works.

The ideas of Socrates
Socrates helped  people to see what was wrong with their ideas. Sometimes they liked this, sometimes they were not happy or grateful. He said that he, Socrates, was not wise, but that he "knew that he knew nothing." Since other people think they know something, but no one really knows anything, Socrates claimed he knew more than anyone else. He said that people who do bad things do so because they do not know any better.

People think that Socrates was a good man because he did no harm, except he asked questions about everything. However, during his life many people thought he was a bad person, because he asked those questions and because he made young people unhappy about their lives.

Someone once wrote that Socrates said that "A life that was not examined was not worth living". This means that someone must think about their own life and its purpose. Some people believe that most humans are happier if they do not think too much about their life.

Socrates also taught that many people can look at something and not truly see it. He asked questions about the meaning of life and goodness. These are still very important questions. Much of philosophy (love of wisdom) is about these things.

Legacy
Socrates is seen by some people as a martyr, since he willingly died to support the idea that knowledge and wisdom are very important to our lives.

Socrates is known as one of the most important philosophers in history. He is often described as the father of Western philosophy. He did not start Western philosophy, but he had a big influence on it. Before Socrates, philosophy was mainly about mathematics and answering questions about our natural world. Socrates expanded on that and added questions about ethics, politics, and epistemology to philosophy.

References

460s BC births
399 BC deaths
Ancient Greek philosophers
Executed people

Socrates


Backward compatibility refers to hardware or software that can successfully use interfaces and data from earlier versions of the system or with other systems. For example, Perl, the scripting language, was designed to be backward compatible with awk, an earlier language that Perl was designed to replace.

Backward compatibility is more easily accomplished if the previous versions have been designed to be forward compatible, or extensible, with built-in features such as hooks, plug-in, or an application program interface (API) that allows the addition of new features.

The term backward combatible (notice the "b") is sometimes used to describe hardware or software that is designed without regard for compatibility with earlier versions, causing the two versions to fight (or combat) each other. In this case, the two versions cannot share data easily and may have features that cause errors or crashes when they are installed on the same computer, often because the computer does not understand which version is being referred to. Even if the earlier version is removed, remaining vestiges of it may cause problems in running the newer version.

Computer terminology

Backward compatibility