juno-labs/simple_wikipedia huggingface dataset:
ELISPOT

**ELISPOT** stands for "Enzyme-Linked Immunosorbent Spot Assay".  It is a laboratory technique for detecting cells that make (or "secrete") various substances.  These substances include specific types of cytokines or antibodies.  The ELISPOT method is typically used with blood cells, and is a helpful tool in studying the human immune system and various treatments for disease (e.g. vaccines).

In the ELISPOT technique, tiny wells are used to contain the cells, with a variety of other substances.  The substances cause colored spots to form near the cells that secrete the substances in question. These spots can then be counted manually (using a microscope, for example) or automatically using specialized equipment with computer vision capabilities.

The ELISPOT technique is very sensitive, and can detect even a single substance-producing cell. It is also very versatile, since it can be tailored to detect a wide variety of very specific secretions.

## Other websites

- A flash animation of the ELISpot procedure
- An animated illustration of the ELISPOT process
- Examples of spot patterns formed by the ELISPOT technique
Billion

**Billion** is a name for a large number. There are two different meanings for the term:
- 1,000,000,000 (, one thousand million) is the short scale definition. It is used in both British and American English. The short scale has been used in the United Kingdom since 1974. Its prefix is “giga-“.
- 1,000,000,000,000 (, one million million) is the long scale definition. It was formerly used in the United Kingdom. It is currently in some other countries. When “billion” has this meaning, the word “milliard” can be used for “thousand million”.

Some examples of billion meaning thousand million:
- Over 1.3 billion people live in India.
- The total land area of Russia is 1.71 billion hectares.
- Billionaires are very rich people. Their wealth is in the billions of dollars, euros or pounds sterling.
- The Age of the Earth is about 4.5 billion years.
- One billion seconds is about 31.5 years.
- The distance to the planet Saturn from the Sun varies from 1.4 billion km to 1.5 billion km.

**Billion** may also refer to:
- _Billions_ (TV series), a Showtime series
- _Billions_ (movie), a 1920 silent comedy
- Billion (company), a Taiwanese modem manufacturer
- Jack Billion (born 1939), 2006 Democratic Party candidate for governor of South Dakota
- _Mr. Billion_, a 1977 movie by Jonathan Kaplan
- "Billions" (song), a song on Russell Dickerson's album _Yours_
White blood cell

The job of **white blood cells** (also called _leukocytes_) is to fight infections and cancer. They also remove poison, waste and damaged cells from the body.

The number of white blood cells increases when a person is fighting infection or disease and decrease when a person is healthy.

### Lymphocytes

Lymphocytes are round white blood cells a bit bigger than a red blood cell. Their center is round and they have little cytoplasm. Part of the lymphatic system, these target specific germs or poisons using their antibodies. There are three known types of lymphocytes, called T-cells, B-cells, and natural killer cells (NK cells).

B-cells make antibodies, which are little molecules that attach to viruses or bad cells. These act like flags to tell other cells to destroy the viruses or bad cells.

T-cells can either help make more B-cells, or kill cells with antibodies.

Natural killer cells kill cells in the body that have been infected by a virus or that are part of a tumor. They are part of the innate immune system.

### Monocytes

Monocytes are reserve cells which turn into macrophages and dendritic cells, which work together in tissues to fight disease. Monocytes have a kidney bean shaped center and lots of cytoplasm. They may appear as macrophages in a non-round shape when they pass through tissue to eat germs, "junk" cells, and dead cells.

### Granulocytes

The next three types of white blood cells are referred to as granulocytes since they all contain rough, grain-like particles that assist in attacking viruses and bacteria. Granulocytes are also called **polymorphonuclear leukocytes** because of the shape of the nucleus, which has three segments.

#### Neutrophils

Neutrophils are the most abundant type of white blood cells in mammals, 70% of leukocytes. They are an essential part of the immune system. They get to the site of an injury within minutes, and make up much of the content of pus. They have a short life-span of a couple of days.

The nucleus, which looks like a string of beads, does not take up stain strongly. Like phagocytes, they actually eat the bacteria and dead cells. They also release a bunch of proteins which work to damage the bacteria.

#### Basophils

Basophils, or basophil granulocytes, are rare granulocytes. If you collected 1000 white blood cells, only 13 of them would be basophils. Their nucleus is hidden by granules which turn dark blue in color when stained. Basophils carry histamine and heparin. They appear at the sites of ectoparasite infection, or allergies. We don't know exactly how they work.

#### Eosinophils

Eosinophils, or _acidophils_, are leukocytes. They are one of the immune system components which combat parasites and certain infections. As with mast cells and basophils, they are sometimes causes of allergy and asthma. Eosinophils are round cells with a lobed nucleus and granules which turn red when stained. These granules are packed with proteins that can be poured out to help destroy invaders.

## Cell testing

A test called a **differential count** shows how many white blood cells there are in a person's blood, and how many of each type are there.
Author

An **author** is a person who makes an original piece of work. Most people use author to mean writer. While a writer is a type of author, authors often do more than write. Anyone who creates something original is an author. These could be written items such as books, stories, or poems. This could also be other types of art, such as sculpture or music. Any type of work can be made by an author.

## _Writer_ and _author_

The term author is commonly used to refer to a person who writes as a profession. It is also believed by many that the term is used for writers who are distinguished and who have had their works published. These explanations are common with people who work with those who write professionally.

An author does not always have to be a writer. If a person dictates a letter to a secretary, then the secretary is a writer, but the person who dictated the letter is the author.

## Examples

Other examples of someone being called an _author_:
- In copyright law, the author is the first owner of copyright. These laws also apply to other works of art, such as pictures or music.
- In biology, the first person to write an article that gives a name to and describes a type of living thing is the author of that name.
- Someone who writes music may be called the author of that piece of music. Another name for an author of music is a composer.

## French usage

When talking about movies, the French word for author, _auteur_, is often used about someone who has been both the writer and director of a movie.

## Related pages

- Writer
- Journalist
- Genre of literature

## Other websites

- Networks of scientific papers
Pedipalp

**Pedipalps** are the two appendages on the front of a spider's head. Other arachnids, and chelicerates that are not arachnids also have pedipalps. Some spiders seem to have ten legs and not eight, because these pedipalps look like an extra pair of legs. The pedipalps are used rather like arms.  Spiders often use them to hold insects (for example crickets) for them to eat.

Male spiders also use pedipalps for mating.  The male spiders make some silk, put sperm onto the silk, and then put their pedipalps into the sperm.  The pedipalps then hold the sperm, and the spider can use it to mate with a female by putting them inside her epigynum.

## Diversity of pedipalps

The pedipalps of all chelicerates vary: Ricinulei, Thelyphonida, Amblypygi, some Opiliones, Schizomida, scorpions and pseudoscorpions all have theirs as pincers, with the Amblypygi's being their entire pedipalps shaped like mantids. The Palpigradi's pedipalps have some of the strangest roles of arachnids as they use theirs for locomotion. The pedipalps of Solifugae act as antennae.

## Other websites

- Close-up view of pedipalps on a large spider
Ionic compound

In chemistry, an **ionic compound** is a compound made of ions. They have strong ionic bonds between particles. Lots of energy (heat) is required to break the bond apart, resulting in high melting and boiling points. The ions join because they have different charges. Compounds of metals and non-metals are usually ionic. They are made when two or more atoms come close together and an electron goes from one atom to the other atom. The electron does this because both atoms want a full outer shell, similar to those of the noble gases.

||Group I|Group II|Group III|Group IV|Group V|Group VI|Group VII|Group VIII|
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|**Example Element**|Na|Mg|Al|C|N|O|Cl|He|
|**Charge**|1+|2+|3+|**See Note 1**|3-|2-|1-|**See Note 2**|
|**Symbol of Ion**|Na<sup>+</sup>|Mg<sup>2+</sup>|Al<sup>3+</sup>|**See Note 1**|N<sup>3-</sup>|O<sup>2-</sup>|Cl<sup>-</sup>|**See Note 2**|

**Note 1**: carbon and silicon in Group 4 usually form covalent bonds by sharing electrons.

**Note 2**: the elements in Group 0 do not react with other elements to form ions

## Physical properties

|Physical Properties|Ionic Compounds|
| --- | --- |
|State at room temperature|Solid|
|Electrical conductivity|As Solid: No Liquid (melted): Yes Dissolved in solution: Yes (if soluble)|
|Boiling point and Melting Point|High|
|Solubility in water|Often high|
|Heat conductivity|Low|
ELISA

The **ELISA** method (**Enzyme Linked Immuno-Sorbent Assay**) is a technique used in biochemistry to determine if a certain substance--such as a specific cytokine or antigen--is present within a sample. It is sometimes abbreviated as "EIA."

This technique uses special antibodies that attach themselves to the substance. These antibodies generate a specific color. The amount of color indicates the amount of substance present. (Sometimes, the substance must be viewed under ultraviolet light for the antibodies to generate this color.)

Another set of antibodies are used to "capture" the substance. These antibodies adhere to both the substance and the testing container, thus holding the substance in place.

A more sophisticated and sensitive technique, the ELISPOT method, was derived from the ELISA techique.

## Other websites

- An animated illustration of an ELISA assay
- Image of a microtiter plate, such as is commonly used in ELISA tests
David Hume

**David Hume** (7 May 1711 – 25 August 1776) was a philosopher and historian from Scotland. When he was still alive, people thought of him as a historian. He wrote a series of large books called _The History of England_. But today, people think of Hume as an important philosopher.

## Works

In his books on philosophy, Hume said that many of our beliefs do not come from reason. Instead, they come from our instincts or feelings. For example, reason does not tell us that one thing causes another. Instead, we see one thing and then we see another, and we _feel_ a link between the two. Similarly, reason does not tell us that someone is a good person. Instead, we see that the person is kind and friendly, and we _feel_ a special moral feeling. Because Hume thought that these beliefs do not come from reason, people call him a "skeptical" or "anti-rationalist" philosopher.

Hume is famous for his 'Induction Fallacy'. This draws attention to a common mistake people make. People see something, and make claims that what they see will always be as they see it. For example, people see only white swans and claim that all swans are white. This is 'fallacious' or mistaken, because it is always possible that they then will see a black swan.

Hume was also skeptical about religion. He was not a religious person and religious people did not like his opinions. He did not believe in miracles. He said that suicide wasn't always wrong, but never said whether or not he believed in God. In 1776, when he was dying, his friends found him very calm about death, despite him not believing in an Afterlife. Today, Hume's books are very important to philosophers who are interested in religion.

## Influence

Today's philosophers sometimes use the term 'Hume's fork' to refer to Hume calling everything we can think about either a relation of ideas (things like mathematics, that must be true) or a matter of fact (like science, where we have to look at things to tell whether or not they are true).

Another philosopher, Immanuel Kant, read some of Hume's books and changed his mind about some important things. Kant said Hume had made him wake up from a sleeping dogmatism, the traditional metaphysics.

## Books

Here are Hume's most important books:

- _A Treatise of Human Nature: Being an Attempt to introduce the experimental Method of Reasoning into Moral Subjects._ (1739-40)
- In this large book, Hume talks about the human mind and tries to figure out how it works. He talks about knowledge, cause and effect, emotions, right and wrong, and many other things.

- _An Enquiry Concerning Human Understanding_ (1748)
- In this small book, Hume talks about many of the same things from the Treatise, like knowledge and cause and effect. He tried to make this book easy to read.

- _An Enquiry Concerning the Principles of Morals_ (1751)
- This is another small book, and again, Hume tried to make it easy to read. The book is about right and wrong.

- _Dialogues Concerning Natural Religion_ (after Hume died)
- In this book, Hume has three characters who argue with each other about God.
Bath

A **bath** (UK English) or **bathtub** (US English) is a basin large enough for people sit in when washing their body.  The bath is usually in the bathroom.  A less common name for a bath is a _washtub_.it can be painted with whiter color, a painted bathtub  have long life.

Sometimes people will add scents, oils and salts to the bath for better experience and relaxation.

A bath is also a place where people can sit in water (or other liquids, often hot) for their health. This is where the town name Bath comes from. Public baths for relaxing were built in all parts of the Roman Empire. The earliest known baths on record appeared somewhere around mid-2000 BC in Knossos, Crete. Another society known for their love of public bathing were the Romans. They invented the _Thermae_, which were grand in size, while _Balineaes_ were smaller in stature. Similar to the Greeks, the Romans also used these places for socialising, while the rich and wealthy would build their own private bathhouses at home.

## Other

- Bird bath
- Bathhouse
- Steam bath
Brush

A **brush** is a tool with bristles or wires or other filaments sticking out. There are many kinds. Most brushes have a long part at one end to hold (the handle), on the other end from the head that carries the bristles or filaments. We use brushes for cleaning, making hair look good, painting, and other purposes.

## Brushes for cleaning

Many kinds of brushes are made for cleaning, for example toothbrushes or brushes for cleaning floors.

## Paint brushes

We use paint brushes for putting ink or paint on paper. If a brush is dipped 1/3 to 1/4 of its length into a can of paint, a good brush will ideally pick up the perfect amount of paint and spread it on a surface in a film that is smooth and uniform and absent of any drips, dips, or brush marks. Paint brushes typically come in two forms, synthetic, and natural. Synthetic brushes are usually made from products such as nylon, while natural refers to bristles from an animal source. Computer graphics uses digital paintbrushes for making pictures.

Paint brushes can have three shapes:
- Round: The long, close-together bristles of these brushes mean they can hold more paint. This is why many artists like them for painting large things and for color washes.
- Flat: These are good for spreading paint.
- Fan-shaped: These mix paint well.

### Brush care

- Clean paint from brushes after you use them. This is very important for oil and acrylic paint because when the paint is dry, taking it off can break the brush.
- Never leave brushes in water (etc.) with the bristle end down. This is because the bristles can change shape.

### Sizes and materials

We can buy brushes in different sizes and materials. Here are some sorts.

#### Decorators' brushes

The sizes of brushes used for painting and decorating (changing the colour or look of a room) are usually in millimeters or inches. This shows how wide the head is.

Here are some sizes:

- 1/8", 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1", 1½", 2", 2", 3", 3", 4".
- 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm.

We can buy brushes with natural or synthetic (man-made) bristles. Handles (the part of the brush we hold) may be wood or plastic.

#### Artists' brushes

Artists' brushes usually have sizes with numbers, but there is no standard.

From smallest to largest, the sizes are:

- 7/0 _(also _ 0000000_)_, 6/0, 5/0, 4/0, 000, 00, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 18, 20, 22, 24, 25, 26, 28, 30.

We use sizes _000_ to _20_ most often.

Bristles may be natural—either soft hair or hog (pig) bristle—or synthetic (man-made).

Artists' brush handles (the part of the brush we hold) are often wooden, but the cheapest brushes may have plastic handles. Many cheap handles are made of unfinished wood; better quality handles are of finished wood.
Starch

**Starch** is a complex carbohydrate. It is made of many glucose units joined by chemical bonds. This polysaccharide is produced by most green plants as an energy store. It is the most common carbohydrate in human diets. Pasta, potatoes, bread, and other starchy foods are made out of carbohydrates.

### Starch in food

Some good food sources of starch are cereals, bread, potatoes, grains, peas, and beans. Starch is also used for thickening sauces in cooking and thickening cold foods during a preheat. Starch is a white powder that is tasteless and odourless. Corn starch or cornflour is known as a popular kind of starch made from corn.

Foods with a lot of starch produce more energy than other foods. However, if this energy is not used, it is turned into fat by the liver through de novo lipogenesis.

### Laundry starch

There are also different kinds of starch, like laundry starch, which gives clothing a smooth and crisp feel. Sweat and dirt from a person’s wrist and neck will stick to the starch on the clothes, not to the fibers of the clothes, and will wash away along with the starch. Then, after each laundry load, the starch can be used again.

## Other facts

Starch glues are used in wood, cotton, and bonding of paper. Animals and humans have amylase, so they can digest starch.
Starch was used in Europe in the 16th and 17th centuries to stiffen the collars and ruffs of the fine linen which surrounded the neck. Starch also requires heat to thicken. The actual temperature depends on the type of starch.
Nicomachus

**Nicomachos** or **Nicomachus** is a Greek name. It can mean:
- Nicomachus of Gerasa, an ancient mathematician

- Nicomachus, the father of Aristotle and court physician (doctor) to King Amyntas III of Macedon. Nicomachus died when Aristotle was about 10. Nicomachus wanted Aristotle to follow in his footsteps. But Aristotle did not become a doctor but a philosopher.
This is a unique name (not in the top 1000 newborn names in the US in 2021).
Logo

A **logo** is a picture or drawing that is used by a person, group, or company to mark who they are. A **wordmark**, or 'logotype', is a logo made entirely of a word or words. It is usually the name of a product or organisation.

A company or group can use a 'logo' on the things that they make, like on the things they sell, on letters, and in advertisements. When a person sees the logo picture, that person knows that the thing they see the logo on came from that company.

Logos can have letters and words in them. Many logos have the name of the company or group in them.

Most logos are very simple drawings with only a small number of colors. Some logos are only in black and white.

In many countries, companies and groups should tell their country's government about the logo they are using. If they do this, the government can help stop a different company or group from using the same logo, so that every one can be sure that the logo is only used by the people who used it first. This is sometimes called a 'trade mark'.

Logos are not used only by companies. Many schools have logos. Some cities have logos. Clubs can have logos. Even people can have their own logos if they want. The heraldic badge is probably the oldest form of logo in the world.

## Related pages

- Logogram
Picture

A **picture**, also called an **image**, is a group of coloured points on a flat surface that looks the same as something else. For example, a picture can look the same as an object or a person. Pictures can also be drawing<nowiki/>s, paintings or photographs. People who make such pictures are called artists, photographers or painters.  Pictures are very helpful.  Sometimes people say pictures are worth a thousand words.  Pictures and diagrams can be used to explain how to do things, and thus a picture is a kind of tool. A moment captured in an image.

An **image** is something that can be seen, but it is not physically there.  It can be a photograph, a painting, or a picture on a television or computer screen.  A lens can make an image of an object appear somewhere else.  Cameras use this to make the image that becomes a photograph.

## Making Pictures

Most pictures today are 'photographs'. Photographs are made with cameras. A camera makes a picture that looks very real.

When there were no cameras, people made pictures by using paint, brushes, pencils, crayons, pens, and other things that people can write or draw with. Pictures made with paint and brush are called 'paintings'. Before cameras, some artists were able to make very real looking pictures with just paint. Sometimes pictures made with pencil or pen are called 'sketches', if they are made quickly and only look a little bit like the real thing.

Usually pictures are put on paper. Pictures made with paint are usually put on a strong, rough fabric called 'canvas'. Sometimes pictures can be put on walls or other things, even glass.

Some places, such as churches have pictures on windows made out of colored pieces of glass. These are called _stained glass_.

## Special types of Pictures

If people take a lot of pictures, and show them one at a time, very fast, they can make a picture that looks like it is moving.  This is called a "moving picture", or a movie.  A television shows people a moving picture by using light.

A slide show is a series of pictures arranged to tell a story, for example to illustrate a narrative.

A projector shines light from a light bulb through a kind of transparent picture.  When light shines through this kind of picture onto a screen or another flat place, the picture can be seen on that flat place.  This is often used to show movies and slide shows to an audience.

Some people make pictures that do not look flat, by taking two regular flat pictures at the same time. People have to move their eyes in a special way or use a stereoscope so they can see both pictures together.  When they look at the pictures using their binocular vision correctly, the picture does not look flat.  This is called '3D' or 'three dimensional'.

Cutaway pictures show what is inside of something, that cannot actually be seen.
Candle

A **candle** is a stick made of wax with a string (a thin piece of rope) straight in the middle. If someone puts the string on fire, the flame burns slowly but for a long time.

Fire can burn string very fast. But in a candle, the string does not burn fast, because the fire melts the wax instead. The wax sometimes drips down the side of the candle. When the melted wax is far from the flame, it gets hard again, and can be used again in a new candle.

The flame is very hot, since it is a very small, real fire. The light blue part of the flame can be as hot as . It can still burn people and things. If the fire spreads, it can grow into a very big fire and even burn down a house or building.

If the flame is kept on the candle long enough, the candle will slowly get shorter and shorter until it is gone. The fire on a candle can be put out by blowing air on it. There is also a special tool called a "candle snuffer" that covers the fire with a small metal cup and puts it out. Today, candle snuffers are usually only used in churches or in places where candles are up very high. Stopping the fire stops the candle from burning until it is all gone.

Before light bulbs, candles were used so people could see at night. Some people still use candles today when electricity is down, or because they like the little amount of light that candles make. Some people also like candles because they look nice, or because they smell nice. A special kind of plant called "citronella" can be infused into the candle to help keep bugs away.

## Related pages

- Lantern
- Electric light
- Advent
Newt

**Newts** or _efts_ are small amphibia. They are in a subfamily of the salamanders. They are found in North America, Europe, and North Asia.

## Life cycle

Females lay eggs and leave them. Tadpoles are born from those eggs.

Newts have three life stages. First as a tiny aquatic larva, which gradually undergoes metamorphosis. Then they leave the water for a year as a juvenile called an _eft_. They go back in the water to breed as adults.

In some species the adults stay in water for the rest of their lives. Others are land-based, but return to water each year to breed.

## Defences

Many newts produce toxins in their skin secretions as a defence against predators. They have bright skin colours as a warning to other animals.

_Taricha_ newts of western North America are particularly toxic; the rough-skinned newt _Taricha granulosa_ of the Pacific Northwest produces more than enough tetrodotoxin to kill an adult human. Recently, a 29-year-old man in Coos Bay, Oregon, who had been drinking heavily, swallowed a rough-skin newt for a dare; he died later that day despite hospital treatment.

Most newts can be safely handled, provided that the toxins they produce are not ingested or allowed to come in contact with mucous membranes, or breaks in the skin. After handling, proper hand-washing techniques should be followed due to the risk from the toxins they produce and bacteria they carry, such as salmonella. It is illegal to handle or disturb great crested newts in the UK without a licence.

## Are newts a related group?

The term "newt" has traditionally been used as a functional term for salamanders living in water, and not a systematic unit. The relationship between the genera has been uncertain, though they may be a natural systematic unit. Newer molecular analysis tend to suggest they actually do form a clade.
Newts only appear in one subfamily of salamanders, the Pleurodelinae (of the family Salamandridae).
Some genera occasionally listed as Pleurodelinae are not newts (_Salamandrina_ and _Euproctus_).
Powder

**Powder** is very small, dry pieces or grains. When we press some dry solids very hard, or when we cut something up into lots of small pieces, we can sometimes make powder.

For example, people sometimes put _face powder_ on their faces, when they want to look good. Sometimes sports players put powder on their hands, to make them dry. We put _curry powder_ in our food, to make it taste stronger. We put _washing powder,_ which is a kind of soap, in the washing machine when we want to have clean clothes. People use _gunpowder_ to make bombs and fireworks.

"Powder" is also a verb - meaning to apply powder.
Larva

Many animals develop in separate stages. A **larva** (plural: _larvae_) develops from the egg in those animals. It is a separate life stage from the adult reproductive stage. A larva does not look like the adult animal, and changes shape (known as metamorphosis) as it grows up. There may be several larval stages before the adult form. Tadpoles, maggots and caterpillars are larvae.

Marine organisms with a larval stage often release large numbers of eggs and sperms into the water column. After fertilisation, the eggs develop into tiny larvae. The larvae develop and grow for some time before metamorphosing into adults. Most marine invertebrates and many fish have a pelagic larval stage or pelagic eggs. These live in the plankton, and may be transported long distances.

## Evolutionary theory

Probably the most widely accepted theory explaining the evolution of larval stages is the need for _dispersal_. Sessile organisms such as barnacles and tunicates, and sea-floor groups like mussels and crabs, need some way to move their young into new territory, since they cannot move long distances as adults. Many species have relatively long pelagic larval stages (how long a larva is in the water column). During this time, larvae feed and grow, and many species move through several stages of development. For example, most barnacles moult through six _nauplius_ larva stages before moulting to a _cipris_, when they look to settle. The larvae eat different food from the adults, and disperse.

The other consideration is the small size of the eggs. If animals lay many small eggs (and most do), then the young stages cannot live the life the adults lead. They must live a separate life until they have the size and capability to live as an adult. This is what the larvae do.

### Origin of vertebrates

A long-standing theory is that in transformed larvae of sea-squirts (tunicates) lies the origin of vertebrates. Tunicates are sessile, but their larvae are mobile, and have some features found in early vertebrates. The process of paedomorphosis, where juvenile features are retained in the adult, is the proposed mechanism. Genome analysis does show that the tunicates are the closest living relatives of vertebrates.
Father

A **father** (also called **dad** or **daddy**) is a male parent. Most human beings are born from a mother and a father. The father of a person's husband or wife is their father-in-law. Fathers determine the gender of their child through a sperm cell which either contains an X chromosome (female), or Y chromosome (male).

## Related pages

- God the Father
- Patriarchy
Gill

**Gills** are what fish, amphibians, and some other animals use to breathe in water. They have feathery parts which cause water to move across the animal's body, which contains dissolved oxygen, after the animal has swallowed the water. The oxygen is absorbed into the animal's blood, causing carbon dioxide to move out of the animal's blood and into the water through the gills.

Fish and frog gills are hidden on the sides of their heads. Sharks have many gills slits on their necks. Baby salamanders have gills that stick out like leaves from their heads.

In mushrooms, **gills** are the spore-bearing structure in agarics (gilled mushrooms) while fish and some young amphibians use them to get oxygen others breath.

Some insects that live in water have a **plastron**, which is a kind of gill. It is a patch of special hairs that keeps the water away from the insect's spiracles. This allows them to continue to take in oxygen and remove carbon dioxide while they are under water.
Wood

**Wood** is what keeps trees and shrubs upright, and what transports water from the roots to the leaves. The two main chemical substances in wood are cellulose and lignin.

Wood is formed in trees and shrubs by the cambium, a cell layer between bark and wood. The result is that wood is formed in circular rings, which are called growth rings.

The wood in the centre of the tree or shrub may have a different color from that on the outside. In that case, the wood on the outside is light in color, and is called "sapwood"; the wood in the centre is darker in color, and is called "heartwood". Most often, heartwood is more resistant to rot than sapwood. Not all trees and shrubs form heartwood, and it is also possible that heartwood differs very little in color from the sapwood, or not at all.

## Use of wood

Wood is used to make buildings and furniture, and also for art. Firewood is a fuel. Paper is made from wood fibres. Wood is a renewable resource although it has become scarcer in recent centuries. Its origin is about 425 million years ago.

Wood is hard to cut, but it is also strong. A lumberjack is a person who cuts down trees. After a tree falls, the wood in it can be cut into long, straight pieces called lumber. Lumber can then be used to make posts, or put together with nails, screws, or even glue to make wooden frames for other shapes.

Wood comes in many different kinds. Oak, maple (hardwood) and pine and redwood (softwood) are widely used types of wood. Woods are usually divided into softwood (from conifers) and hardwood from flowering plants.

## Housing

For a long time and even today, many buildings, mostly houses, have been made of wood. To build a house with wood, lumber is put together into frames that are the shape of each wall, floor, and roof of the house. Then the frames are placed into the shape of a house. Then the frames can be covered to make solid walls. Sometimes the walls are made of more wood.

When the outside of a house or building is covered in wood, the wooden pieces are usually flat and stacked. These pieces are called shingles. Wood is also sometimes used in other parts of the house, like doors and staircases. Wood is also used to make fences.

## Carpentry

Carpenters make houses of mostly soft wood such as pine. For many kinds of furniture they use harder wood such as maple or oak. When someone builds something with wood, they often paint it. Paint protects and beautifies the wood. Some people like the look of wood, so they put clear paint called _varnish_ on it. This helps to protect the wood and gives it a shiny finish.

Some people make art with wood. Sometimes sculptures are built with wood: see Grinling Gibbons.

Regular pencils are made of wood. Inside is the "lead", which is not actually lead. Clay or wax and graphite form the "lead" in a pencil.

## Paper

Wood is turned into paper in large factories called paper mill<nowiki/>s.  Heat, chemicals and machines separate the cellulose fibers from other parts and press the fibers into paper.

## Related pages

- Tree
- Petrified wood
- Plywood
- Firewood

## Other websites

- Wood -Citizendium
Chalk

**Chalk** is a type of limestone. It was made by calcareous (CaCO<sub>3</sub>) skeletons of tiny planktonic algae called coccoliths. They live in the sea in huge numbers. They make chalk (CO<sub>2</sub>) as a by-product of their photosynthesis. The chalk cliffs of Dover and elsewhere were made when England was below the equator in a tropical sea. It was in the Upper Cretaceous, when the Earth was even warmer than now. There are coccoliths today, but not the same species as formed the white cliffs.

Air and water do not wear chalk away easily, so when chalk is next to the sea, it often makes a large cliff. The "White Cliffs of Dover" in Kent, England are a good example of this. Chalk holds water, so these chalk hills may have a lot of water in them. When the weather is very dry, water comes slowly from the chalk.

**Blackboard chalk** is not real chalk. It is really gypsum (calcium sulfate), but people call it "chalk". People use it for drawing on hard things, because it is soft. If this chalk is rubbed on something hard or rough, it will leave a mark. People often write with chalk on a chalkboard or blackboard. A chalk eraser or water can be used to clean the chalk marks away so the board is clean again. Shops usually sell blackboard chalk in sticks that are about 5 cm long.

There are also big pieces of soft chalk for children to write on the ground with, for example on concrete (such as a sidewalk) or on asphalt. It is usually okay to write on the ground with this kind of chalk, because the rain will wash the chalk away.

**Tailors' chalk** is not real chalk either. It is talc (magnesium silicate). Tailors use it to draw on material when they are making clothes.
Utilitarianism

**Utilitarianism** is the view that the right thing to do is whatever is most useful. It is a  about ethics. The word "utilitarianism" comes from the word "utility", which means "usefulness". In most forms of utilitarianism, things that increase human well-being or happiness are called useful. This is not limited to the happiness caused by a single action but also includes the happiness of all people involved and all future consequences.

In general, the theory of utilitarianism is that whatever brings the most happiness to the greatest number of people is the right thing to do.

## History

The theory was made popular by 18th and 19th century British philosophers like Francis Hutcheson, Jeremy Bentham, and John Stuart Mill, but the idea goes all the way back to ancient times.

Bentham wrote about this idea with the words "The greatest good for the greatest number," but did not use the word _utilitarianism_. It was Mill, a follower of Bentham's ideas, who named the idea.

## Utilitarianism in Practice

Many philosophers argue that utilitarianism has important practical implications for how we should live ethically. For instance, according to utilitarianism we should help the poor, prevent animal suffering, and ensure that future generations have good lives.

## Related pages

- Hedonism
- Happiness pump
Village

A **village** is a place where people live, normally in the countryside. It is usually larger than a hamlet and smaller than a town or city.  In some places, it may be a kind of local government. The dwellings in a village are clustered fairly near one another, not scattered broadly over the landscape.

In the past, villages were where most people lived. Villages were a usual form of community for societies that do subsistence agriculture, and for some non-agricultural societies. After the industrial revolution, when people started making a lot of things in factories, people lived more in towns. Moving to towns is called urbanization. When villages grow a lot they can grow into towns and then cities. This is what happened to Athens and Chicago.

## United Kingdom

In The U.K. the main difference between a hamlet and a village is that many villages have a church.

Most villages are long-standing. The land has been settled (peopled) since the ice age. The soil is generally very fertile, and the land was once heavily forested. Much of what was forest was cut down to make ships, and farming replaced it. The land is fertile because of the deep loam (soil) in many places. That is partly due to the ice age, since the ice cover moved and ground against the bedrock.

### Incorporated villages

The word "village" is not used in most states. However, in twenty  US states, a "village" is a sort of local government, similar to a city but with less power and for a smaller place. But this is not so in all the United States. In many states, there are villages which are bigger than the smallest cities in the state. The difference is not the population, it is how much power the different sorts of places have, and what they do for people living there.

#### New York

In the state of New York, a village is a place which is usually called a town.

### Unincorporated villages

In many states, a "village" is only a place where people live, with no legal power, similar to a hamlet in New York state. The name for these is "unincorporated villages".
Gangnihessou

**Do-Aklin** or **Gangnihessou** (Ganye Hessou) or **Dogbari** was the first of twelve kings of Dahomey in Africa. Gangnihessou might have been the king around the year 1620. One of his symbols was a bird called "gangnihessou" after his name. His other symbols were a drum, and sticks used for throwing or hunting. He had a younger brother called Dakodonou, who was a king. Some historians think Gangnihessou was not actually a king. Instead, Gangnihessou might have led people by giving advice to his brother.

## Infobox (monarch)

- **name**: Do-Aklin
- **title**: Founder of the ruling dynasty of the Kingdom of Dahomey
- **reign**: c. 1600
- **successor**: Dakodonou
- **royal house**: Aladaxonou
No

**No** is an English word that has a negative meaning. It is the opposite of the word _yes_, which is a positive term.

_No_ is used when someone is turning away something. It is also used when opposing an idea. It can also be used in different figures of speech.

In both sentences and talking, the words "No" and the word "Not" can both be used, though the word "No" is mainly used when speaking to other people. In some cases, however, "Not" is not acceptable, and vice versa. These words are not to be confused with the similar sounding words know and knot.

Examples of  of "No" and "Not":
- Is this green? No, it is not.
- There is no way round the back.
- This is not the way (but there is another way).
- I will not come.
- Oh, no!
- No, thank you.
- Not on my watch!
- I can not go anywhere.

Examples of  of "No" and "Not":
- That is no the way you do it.
- Oh not!
- I know how to tie a knot. _(Disambiguation)_
- I didn't no that!
- I can no go.
- Not way!

When there are multiple "no's" in a sentence, if the number of "no's" is even then the "no's" together mean "yes" (because when saying "no no", the first _no_ cancels the second _no_). If the number of "no"'s is odd then together they mean "no".
Leon Trotsky

**Lev Davidovich Bronstein (** (; also transliterated _Leo_, _Lev_, _Trotskii_, _Trotski_, _Trotskij_ and _Trotzky_; 26 October (O.S.) = 7 November (N.S.), 1879 in Kropyvnytskyi (Russian Empire, now in Ukraine) - 21 August 1940 in Coyoacán, Mexico) was the pseudonym of **Leib** or **Lev Davidovich Bronstein**. He was a Russian revolutionary and political theoretician of Jewish-Ukrainian descent.  After leading the Red Army in the Russian Civil War, he disagreed with other Bolsheviks,. had to leave Russia, and was later killed under Stalin's orders.

## Life

Trotsky was a socialist and a Marxist. During the 1905 attempt at a revolution in Russia, Trotsky helped organize a committee of workers that was called the "soviet" in the Russian capital, Saint Petersburg. When the leader of the soviet was arrested, Trotsky took his place. Trotsky helped to expand on the idea of permanent revolution, a theory that had been originally thought up by Karl Marx. After the revolution's failure, Trotsky left Russia for his own safety.

In 1917, he returned to Russia because of the Russian Revolution. He successfully helped to bring about communism in Russia and to defend it during the Russian Civil War while was in charge of the Red Army. After the death of the leader of the Bolsheviks, Vladimir Lenin, Trotsky became involved in a power struggle with Joseph Stalin for the leadership of the party. Trostsky lost despite being Lenin's preference, and Stalin came to power.

## Death

Trotsky had to leave Russia because of Stalin, who was now an enemy of Trotsky and wanted to harm him. In 1938, Trotsky founded the Fourth International. Stalin tried several times to assassinate Trotsky. Stalin had one of his spies, Ramón Mercarder from Spain, fatally stabbed Trotsky with an ice axe in Mexico in 1940 with the help of Lavrentiy Beria .

## Trotskyism

People who believe in Trotsky's ideas are called Trotskyists and follow Trotskyism.  Trotskyism is seen as being a more democratic form of communism than others, such as Stalinism and Maoism. The main Trotskyist organizations are now the Socialist Workers Party in the United Kingdom and the International Socialist Tendency worldwide.

In the novel _Animal Farm_ by George Orwell, Trotsky is represented by Snowball, a pig, and Stalin is represented by Napoleon, another pig. The book reflected real-world events.

## Other websites

- Fourth International (post-reunification)
- Story of Trotsky's Murder
- Trotsky's Grave
Second International

The **Second International** (1889–1916) was an organization created on July 14, 1889, by socialist and labour parties who wanted to work together for international socialism. It continued the work of the First International, which stopped being an organization in 1886. However, it did not include the still-powerful anarcho-syndicalist movement and trade unions.

Among the Second International's most famous actions were its 1889 declaration of May 1 as International Labor Day and its 1910 declaration of March 8 as International Women's Day.

The International's permanent executive and information body was the International Socialist Bureau (ISB). It was located in Brussels and formed after the International's Paris Congress of 1900. Emile Vandervelde and Camille Huysmans of the Belgian Labour Party were its chair and secretary. Vladimir Lenin was a member from 1905.
Dadabhai Nauroji attended its Paris commune in 1906.
Insectivore

An **insectivore** is an animal or insect that eats mostly insects for food. An anteater is an animal that eats ants. Insectivorous plants also eat insects. The Venus flytrap is one of them.

To eat insects for food is not very easy because insects are small. Large insect-eating animals must eat many of them. Anteaters eat hundreds of ants every day.

Some omnivores like humans and bears also eat insects for food. There was once a taxonomic group of mammals called Insectivora. Most of its animals are now called Eulipotyphla.

## Related pages

- Herbivore - an animal that eats mostly plants
- Carnivore - an animal that mostly eats meat from other animals.
- Detritivore - an animal that eats garbage, dead animals or other food left from another animal.
- Omnivore - an animal that eats animal meat, plants, fruit, and insects.
Copy

**Copy** means a thing that is made to look like another thing.

- Copying, making a copy, the duplication of information
    - Photocopying, a process which makes paper copies of documents and other visual images
    - Fax, a telecommunications machine used to transfer copies of documents over the telephone network
    - Facsimile, a copy or reproduction that is as true to the original source as possible
    - Replica, a copy closely resembling the original concerning its shape and appearance
- Copy (written), commonly used in newsrooms and publications to refer to a writer's written content
Vapor

**Vapor** (British English: **vapour**) is when small drops of liquid float in the air.  Sometimes this happens because the liquid has been heated.  Vapor is not the same as gas.  It is a mixture of liquid and gas. The usual word for this is steam.
Vehicle

A **vehicle** is a machine to move people and things. A vehicle is not alive. A horse can move people and things, but it is an animal, not a machine or a vehicle.

The word vehicle is borrowed from French and Latin. French _véhicule_, going back to Middle French, borrowed from Medieval Latin _vehiculum_ "medium, agent of transmission," going back to Latin, "wheeled vehicle, means of transport," from _vehere_ "to carry, convey.

### Land vehicles

Some vehicles move on land. Most land vehicles have wheels. Examples of land vehicles are bicycles, cars, trucks, buses, motorcycles, and trains.

Land vehicles that are powered by an engine or motor are called motor vehicles.

Some land vehicles, like tanks and snowmobiles, have tracks. These tracks look and work like conveyor belts.

### Water vehicles

Some vehicles move on, or in, the water.  Examples are boats, ships, and submarines.

### Air and space vehicles

Vehicles that move in the sky are called aircraft.  Examples are aeroplanes and balloons.

Some vehicles, like the Space Shuttle, can even leave the Earth's orbit and go to outer space.

## Power

Vehicles can be propelled by various sources of energy.

- Human muscles.  Examples are bicycles and skateboards.
- Engines.  Examples are automobiles, ships, and aeroplanes.
- Electricity.  Examples are many passenger trains.
- Animals.  Examples are carts and chariots.
- Wind.  Examples are sailboats and iceboats.

Some vehicles have no propulsion power.  Examples are gliders, balloons and even fixed tower cranes.