Aarushhh/wikipedia-simple-splitted huggingface dataset:
Uses
The main use for krypton is to make light. There is one main type of krypton light bulbs. This is called a gas discharge lamp. There are three main types of these. First is a low energy gas discharge lamp or "neon light". Low energy gas discharge lights made from krypton are near white to green. Second is a high energy short length of time gas discharge light or "flash bulb". These are mostly used for photography. They are bright blue-white. Third is a high energy gas discharge light. This third kind is mostly used to light airport runways. They are also bright blue-white.
History
Krypton was found by Sir William Ramsay and Morris Travers in Great Britain in 1898. Ramsay was given the 1904 Nobel Prize in Chemistry for his work on noble gases. It was a difficult gas to discover; Ramsay suspected it existed but only found it by removing other gases. This is why he gave it the name Krypton. There is no mineral called Kryptonite or planet called Krypton, which both feature in the Superman comics by Jerry Siegel and Joe Shuster. The fictional planet is probably better known than the real chemical element called Krypton.

Related pages
List of common elements
Periodic table

References

Noble gases
The noble gases are a group of elements that are all gases. These elements are all in group 18 of the periodic table. All of them are monoatomic, meaning each molecule is a single atom. They almost never react with other elements. This is because they have a full 8 electrons outer electron shell. There are six noble gases:

 helium
 neon
 argon
 krypton
 xenon
 radon

All of these gases are found in air. They make up around 0.96% of the atmosphere. Noble gas compounds can be formed from noble gases.

When the noble gases are used in cold cathode tubes to produce light, each of them has a different colour. Since Radon is radioactive, it is usually not used for lighting. Here are pictures of what the others look like:

Oganesson (element 118) is probably the next noble gas after Radon because it is the next box down in the same group. However it has a half life of 0.89 ms, after which it decays to Livermorium (Element 116). This means its use is probably limited.
Noble gases were discovered by Lord Rayleigh and Sir William Ramsay. Rayleigh won the Nobel Prize in Physics in 1904 for his work on noble gas. Ramsay won the Nobel Prize in Chemistry in 1904 for his work with noble gas.

References
Polonium is a rare radioactive metalloid. It is chemical element 84 on the periodic table and its symbol is Po. It was discovered in 1898 by Marie and Pierre Curie.

Polonium is highly unstable, radioactive and toxic. This makes it difficult to handle. It can be dangerous, even in very small amounts. One gram of Po will self-heat to a temperature of about . It also vaporizes easily.

Polonium has 33 isotopes, and all of them are radioactive. It is a very rare element in nature because of its short half-life. It is a breakdown product of uranium, so it is found in uranium ores. 

Polonium is also very important because it the main element of nuclear bombs.

References 

Post-transition metals
Bismuth is a chemical element. It is element 83 on the periodic table and its symbol is Bi. Its atomic mass is 209. It is only slightly radioactive. The radioactivity is minimal so it is typically seen as nonradioactive. Bismuth is only naturally found as one isotope, which is the almost nonradioactive one. Its radioactivity was predicted by scientists and proven by analyzing the metal. It is in Group 15 on the periodic table.

Properties

Physical properties 

Bismuth is a silver metal with a pink tinge to it. This pink color is because of its oxide coating.  Bismuth is a post-transition metal.  It is one of the strongest diamagnetic metals.  It is almost as heavy as lead.  It is quite brittle.  It can make crystals with a shiny surface.  Its melting point is quite low: , which is normal for post-transition metals.  As a liquid it is denser and has a smaller volume than as a solid.  Another chemical that does this is water.  It does not conduct electricity or heat very well.
Chemical properties
Bismuth is somewhat similar to antimony. Bismuth makes a thin coating of bismuth(III) oxide when it is in air. This makes the colors on the crystals. It does not oxidize any more than the oxide layer. It burns when powdered with a bright blue flame, making yellow bismuth(III) oxide fumes.  Bismuth also reacts with sulfur, when molten.  Bismuth reacts with nitric acid to make bismuth(III) nitrate and concentrated sulfuric acid to make bismuth(III) sulfate and sulfur dioxide.  It reacts with halogens to make bismuth(III) halides but with fluorine it makes bismuth(V) fluoride unless the fluorine is diluted.
Chemical compounds
Bismuth forms chemical compounds in two main oxidation states: +3 and +5. +3 is more common. +3 compounds are weak oxidizing agents and are normally light yellow. +5 compounds are strong oxidizing agents. Bismuthates are the most common +5 compounds. Bismuth(V) fluoride is another +5 compound. Bismuth(V) oxide is an unstable red solid. Bismuth sulfide is a common ore of bismuth. Bismuthine, a bismuth hydride, is very unstable and only can be made at very cold temperatures. Bismuth makes many oxy- compounds like bismuth oxychloride. These compounds are made when bismuth halides dissolve in water.

Trioxides

+3 compounds are weak oxidizing agents except for bismuthine. They are normally pale yellow.
Bismuthine, unstable gas
Bismuth(III) bromide, pale yellow solid
Bismuth(III) chloride, pale yellow solid
Bismuth(III) fluoride, gray white solid
Bismuth(III) iodide, dark gray solid
Bismuth(III) oxide, pale yellow solid
Bismuth(III) oxychloride, whitish solid
Bismuth(III) sulfide, brown solid
Pentoxides
Bismuth(V) oxides (+5 compounds) are very strong oxidizing agents. Its chemical formula is Bi2O5. It is a scarlet red solid. It decomposes to bismuth(III) oxide and oxygen easily. It is made by electrolysis of bismuth(III) oxide in a hot concentrated alkali like sodium hydroxide.
Bismuth(V) fluoride, colorless solid
Bismuth(V) oxide, unstable red solid
Bismuthate, the ion
Sodium bismuthate, light brown solid, insoluble in water

History
Bismuth was known since ancient times. It was confused with tin and lead, though. No one is credited for discovering bismuth. In the 1500s, people started realizing that bismuth was different than tin or lead.

Occurrence

Bismuth is not very common in the earth. It is only about twice as common as gold. Bismite, a bismuth oxide mineral, and bismuthinite, a bismuth sulfide, are two common ores. Bismuth is sometimes found as a metal, too.
Preparation
Bismuth and its minerals are too rare to be mined. They are gotten by "secondary extraction". It is normally found in lead metal. The lead metal is purified by electrolysis, leaving the bismuth behind as a sludge on the bottom of the container. The copper is taken out of the sludge and the bismuth is purified by being reduced in a furnace and all the impurities are filtered out.

China makes the most bismuth. Peru, Mexico, and Japan also make bismuth.

Bismuth can also be recycled. This is difficult in many places because bismuth is used for things like bullets, solder, and stomach medicine that get scattered all over and cannot easily be gotten again.

Uses
Uses

As an element
Bismuth is used in alloys with very low melting points. Some of them melt in hot water. They are also found in solder that does not have lead in it. It can make alloys with other metals to make them more malleable. It is also used in bullets to replace lead. In some places lead bullets are outlawed as birds eat them and get lead poisoning. It is also used in alloys for plumbing. It is used in fishing sinkers.

As chemical compounds
Bismuth is used in some medicines such as Pepto-Bismol. This medicine has bismuth subsalicylate in it. It is also used as an internal deodorant and to treat eye infections and peptic ulcers.

Bismuth oxychloride is used in cosmetics. Bismuth telluride is used in electronic thermometers. Another compound is used in superconductors and becomes a superconductor at a high temperature. It can be used as a pigment and in fireworks to make crackling sounds. It is used in the nuclear fuel of a nuclear reactor.
Safety
Bismuth is much less toxic than other heavy metals. This is why it is replacing lead in many things. It does not add up in the body like other heavy metals do. A very large amount of bismuth can poison the kidneys and liver, though. Because its oxide does not dissolve in water, it is considered safe for the environment.

Post-transition metals
Iridium is the 77th element on the periodic table. Its symbol is Ir and its atomic number is 77.

Chemistry 
Iridium is a metal. Like other metals in the platinum group, Iridium is a rare and expensive "noble metal" and is a transition metal. It looks like platinum and is found in asteroids and comets. It is exceptionally hard-wearing. 

Iridium deposits are used to identify relative dates of collisions of foreign bodies. Iridium can fold and bend just like aluminum, and remains very shiny. Most iridium is found in the Americas, though some is mined in Myanmar, South Africa, and Russia. Iridium melts at 2410 °C, and boils at 4130 °C. It is the most corrosion-resistant metal.

Iridium is not needed in the body. It is used for the tips of pens. The main uses of iridium are the metal itself and its alloys.
History 
A man named Smithson Tennant first found it in the year 1803 and is was named after Iris in Greek mythology. Smithson Tennant found it in the remains when he left crude platinum in a mixture of hydrochloric acid and nitric acid.

Transition metals
The transition metals are a group of metals that are found in the middle of the periodic table. The alkaline earth metals, beginning with beryllium are to the left and the boron group elements are to the right. The term "transition element" was invented for them in 1921.

The atomic numbers of these metals are from 21 to 30, 39-48, 57, 72-80, 89 and 104-112. Many elements like Zn, Cd, Hg, La and Ac have a highly debatable position in the transition series of elements. La and Ac are also classed in the lanthanide series and actinide series respectively.

Transition metals have several general properties. They are harder and less reactive than the alkaline earth metals. They are also harder than the post transition metals. They make colorful chemical compounds with other elements. Most of them have more than one oxidation state. Like other metals, they are electrical conductors.
Some of the transition metals are necessary to keep humans healthy, such as iron, zinc, and chromium. Other elements in the transition metals can be harmful to our body, like cadmium and mercury. Other elements like gold or silver do not harm or help us. There are more transition metals than any other groups in the periodic table.

Only a few of the transition metals are colored; most of them are silver-gray or silver-bluish.
Characteristics 
Osmium has a blue-grey hue and is the densest stable element; it is about twice as dense as lead and slightly denser than iridium. Osmium is a hard but brittle metal that stays shiny even at high temperatures. It has a very low squeezability. Accordingly, its size module is extremely high, reported between 395 and 462 GPa, which is comparable to that of diamond (443 GPa). The hardness of osmium is moderately high at 4 GPa.  Because of its hardness, brittleness, low vapour pressure, and very high melting point, solid osmium is difficult to machine, form, or work.

Transition metals
Radon'' is a chemical element in the periodic table. It is element 86 on the periodic table and its symbol is Rn'''. It is an odorless, tasteless noble gas. It is quite radioactive and can decay very quickly. 27 isotopes of Radon is known today. The most stable of them has a half life of about 3.8 days.

Chemistry 
Radon is a gas and is part of the group known as the noble gases.  It does not react with other elements, so it is found pure. Radon is radioactive, meaning that it can give off harmful rays.  Some people have high levels of radon in their houses, and this can be very dangerous.  A lot of radon can get stuck in the basement of old houses, and so people end up breathing it in.  It gets stuck in the lungs and has been known to cause cancer.  There are groups that try to make sure there is no dangerous radon in houses.

It can occur naturally on the Earth but is a very small amount. As elements like Thorium and Uranium decay, some of that gets turned into Radon.
Radon can cause lung cancer and is the second most popular cause of lung cancer straight after smoking.

History 
Radon was the fifth radioactive element to be discovered, in 1899 by Ernest Rutherford and Robert B. Owens at McGill University in Montreal, after uranium, thorium, radium, and polonium. In 1899, Pierre and Marie Curie saw that the gas given off by radium remained radioactive for a month. Later that year, Rutherford and Owens noticed different types of them when trying to measure radiation from thorium oxide.

Uses 
It is sometimes used in radiation therapy. However, it is very dangerous to use.

Related pages
List of common elements
Periodic table

References 

Noble gases
Carcinogens
Most modern operating systems support FTP. This implies that any computer connected to a TCP/IP based network can manipulate files on another computer on that network regardless of which operating systems are involved, provided that they are open to FTP connections. There are many existing FTP client and server programs, many of these are available free, or open source.

FTP connection is also seen in cellular phones when trying to transfer or receive data from a computer nearby.

FTP return codes 

FTP server return codes show their status by the digits within them. A short explanation of various digits' meanings are given below:
1xx: Positive Preliminary reply. The action requested is being initiated but there will be another reply before it begins.
 2xx: Positive Completion reply. The action requested has been completed. The client may now issue a new command.
 3xx: Positive Intermediate reply. The command was successful, but a further command is required before the server can act upon the request.
 4xx: Transient Negative Completion reply. The command was not successful, but the client is free to try the command again as the failure is only temporary.
 5xx: Permanent Negative Completion reply. The command was not successful and the client should not attempt to repeat it again.
 x0x: The failure was due to a syntax error.
 x1x: This response is a reply to a request for information.
 x2x: This response is a reply relating to connection information.
 x3x: This response is a reply relating to accounting and authorization.
 x4x: Not used.
x4x: Not used.
 x5x: These responses indicate the status of the Server file system vis-a-vis the requested transfer or other file system action.
FTP modes 
FTP may run in active or passive mode, which determines how the data connection is established. In both cases, the client creates a TCP control connection from a random, usually an unprivileged, port N to the FTP server command port 21.
 In active mode, the client starts listening for incoming data connections from the server on port M. It sends the FTP command PORT M to inform the server on which port it is listening. The server then initiates a data channel to the client from its port 20, the FTP server data port.
 In situations where the client is behind a firewall and unable to accept incoming TCP connections, passive mode may be used. In this mode, the client uses the control connection to send a PASV command to the server and then receives a server IP address and server port number from the server, which the client then uses to open a data connection from an arbitrary client port to the server IP address and server port number received.
Encryption 
 File Transfer Protocol Secured (Using SSL / TLS)
 SSH File Transfer Protocol (Using SSH)

FTP Servers 
Some popular open source FTP server implementations are:
 FileZilla Server (Windows)
 Pure-FTPd (Unix)
 VsFTPd (Unix)
 ProFTPd (Unix)

Other websites
 
 FTP Server Online Tester Authentication, encryption, mode and connectivity.

Internet
Computer protocols
Hypertext Transfer Protocol (usually abbreviated to HTTP) is a communications protocol. It is used to send and receive webpages and files on the internet. It was developed by Tim Berners-Lee and is now coordinated by the W3C. HTTP version 1.1 is the most common used version today. It is defined in RFC 2616.

About half of websites already use its successor HTTP/2 (which almost all web browsers support), and 25% of websites already support its much faster successor HTTP/3, which is the latest version of the protocol, published in 2022. HTTP/3 has lower latency for real-world web pages, if enabled on the server, load faster than with HTTP/2, and even faster than HTTP/1.1, in some cases over 3× faster than HTTP/1.1 

The secure variant of HTTP is called HTTPS (Hypertext Transfer Protocol Secure), and is used by more than 79% of websites, such as payment websites (if it's not used, then it's a clear signal that the payment site is a scam).
HTTPS is used by default by most web browsers (even if not requested by the user), assuming the web server supports it. If browsing to a website, and the web browser shows it starting with http: without an s before the colon (or an unlocked icon is seen), then that website is not secure, then passwords or other data sent to them can be stolen. HTTPS encrypts all the information that is sent and received. This can stop malicious users such as hackers from stealing the information. HTTPS uses port 443 for communication instead of port 80.

HTTP works as such, a user agent, usually meaning the web browser, connects to a (web) server. A user agent could also be a web crawler, or so-called "spider", but most users do not use such tools (they are used by search engines, such as Google). The server must be located using a URL or URI. It normally connects to port 80 on a computer.

Request message
Request message 

The request message (for HTTP/1.1 and older) contains the following (i.e. it's in plain text; no longer used with HTTP/2 and later):

 Request line, such as GET /images/logo.gif HTTP/1.1, which requests the file logo.gif from the /images directory
 Headers, such as Accept-Language: en
 An empty line
 An optional message body

The request line and headers must all end with two characters: a carriage return followed by a line feed, often written <CR><LF>. The empty line must consist of only <CR><LF> and no other whitespace. In the HTTP/1.1 protocol, all headers except Host: are optional.

A request line containing only the path name is accepted by servers to maintain compatibility with HTTP clients before the HTTP/1.0 standard.

References

Internet
Computer protocols
Ethernet is a way of connecting computers together in a local area network or LAN. It has been the most widely used method of linking computers together in LANs since the 1990s. The basic idea of its design is that multiple computers have access to it and can send data at any time. This is comparatively easy to engineer. 

If two computers send data at the same time, a collision will occur. When this happens, the data sent is not usable. In general, both computers will stop sending, and wait a random amount of time, before they try again. A special protocol was developed to deal with such problems. It is called Carrier sense multiple access with collision detection or CSMA/CD.

Different cable types
There are different Ethernet standards.  Today, Ethernet cables look like thick telephone cables.  They connect to boxes called hubs or switches. Each cable runs from a computer's network interface card (NIC) to such a box. This cable is called 10BaseT or 100BaseT, or 1000BaseT Cable.
All cable types:
 10Base2 and 10Base5: These coaxial cables are like those used in television, but thinner.  They are also called "thinnet" or "coax". Each computer has a "T" plugged into it, and cables plug into each side of the "T". Sometimes, instead of a "T", a vampire tap is used. It supports 10MBits per second transfer speed. It was the first to be adopted, and became rare during the 21st century.
 10BaseT: Cables look like thick phone cables, but with 8 copper wires instead of 2 or 4, and they go from each computer' to a Hub or a Switch. Supported speed is 10 MBit/second.
 10BaseF: Same as 10BaseT, but cables transmit light pulses, instead of electrical signals.
 100BaseT:  Cables look the same as 10BaseT, but can run at up to  100 MBits per second
 1000BaseT: Cables look the same as 10BaseT, but can run at up to 1GBit (1000MBit) per second.
Today, the cables for 10BaseT, 100BaseT, and 1000BaseT are the same. Their transmission medium is unshielded twisted pair for Category 5 (UTP-Cat5) or 5e. Shielded cable (STP-Cat5 or Cat5e) can be used when there is a lot of electrical noise, and Category 6 (UTP-Cat6 or STP-Cat6) works better with faster signals such as 1GBit or 10GBit.

Different devices
Other devices, such as video game consoles, can also be connected using the same kind of cabling. Certain computer peripherals, for example printers and certain hard disks can be directly connected to the network with such cables.
Different speeds
Ethernet can go at different speeds. In the beginning, Ethernet was at 10 MBits per second. The Ethernet most often used today is at 100 MBits per second.  Most new computers now have the NIC built in, and can go at 1GBit per second. There are also standards for 1GBit per second and 10 GBit per second.  100 MBit can usually talk to 10 MBit, and 1 GBit can talk to 100 MBit and usually to 10 MBit (both full and half duplex).

Computer hardware
Computer networking
Obesity is the condition of being much too heavy for one's height so that one's health is affected. In other words, it means to be too overweight. Also known as being fat. It is considered a disease and has been described as an epidemic and a form of suicide.

To know if a person is overweight, the body mass index (BMI) is calculated, by dividing the person's weight (in kilograms), by their height (in metres) squared (multiplied by itself). (This is only meaningful for adults who are fully grown, and should not be used for children. Growth charts can be used to measure obesity in children.)
A BMI between 18.5 and 25 is considered normal. People with a BMI of 25 or more are said to be overweight; with 30 and above, they are considered obese, and with 35 and above, they are considered severely obese (this used to be called morbidly obese). In general, the BMI number is a good quantifiable measurement of a person's obesity. However, it is a poor predictor in people who are very athletic, because a person with a higher than average amount of muscle tissue will weigh more than an average person, thus resulting in a BMI that is higher than normal, even if that person is very large.

Causes
Causes

The most common cause for obesity is eating more calories than are used by the body. Other factors that often contribute to obesity are:
 Poor nutrition
 Hormonal problems (for example, caused by hypothyroidism)
 Problems with the metabolism, e.g. weight cycling (the so-called yo-yo effect)
 Eating disorders (for example, binge eating disorder)
 Psychological problems, like depression
 Lack of sleep or sleeping problems
 Lack of exercise

Genetics are known to contribute to obesity. Low levels of leptin, a hormone, is linked to obesity.

Health issues
Many health problems are associated with obesity. An example is Type 2 diabetes. A woman with a BMI higher than 35 is 93 times more likely to develop diabetes. A 2009 review found that people with a BMI between 40 and 50 were 22.5 times more likely to die from diabetes than people with BMIs between 22.5 and 25.

An obese woman is more likely to have an unhealthy baby.
Risk is associated with where the excess fat is stored on the body. Abdominal obesity is particularly dangerous.

Some people think that the idea that obesity causes bad health is not completely true and has been exaggerated. An example is J. Eric Oliver. He wrote a book called Fat Politics: The Real Story Behind America's Obesity Epidemic. There is evidence for this belief.
The Centers for Disease Control and Prevention said in 2003 that 400,000 people died because of being obese in 2000. Then in 2004 they said that the number was wrong. A 2013 review of scientific papers found that Grade 1 obesity (BMI 30-34.9) is not associated with increased deaths. Grades 2 (BMI 35-39.9) and 3 (40+) obesity are associated with much higher rates of death. It has been suggested that obesity is associated with mortality (death) because of mortality in Grade 2 and 3 obesity. People with grade 2 and 3 obesity are 29% more likely to die.
'Metabolically healthy obesity' is increasingly being recognized. Up to 40% of obese people are metabolically healthy. They are not more likely to get heart disease or die than metabolically healthy non-obese people.

The 'obesity paradox' is a term used to describe how obesity can lower the risk of death. Obesity increases the chance of getting heart disease. But obese people with heart disease are less likely to die in a 7-year period. The obesity paradox has also been found in patients with stroke, diabetes, and chronic obstructive pulmonary disease.
Treatment
Scientists have not yet found a 'cure' for obesity that most people are willing to implement. It is common wisdom that people who lose weight will regain it all within 5 years.
However, this position has been scientifically challenged for over a decade. Additionally, modern research has achieved significantly higher success rates than the figure that dominates the popular internet. Therefore, diet and exercise is the most common recommended treatment for obesity - it has the potential for a very high treatment success rate.

Surgery can be used to treat obesity. Gastric bypass is the most common weight loss surgery. It makes a person's stomach smaller so that they feel full after eating less food and causes their body to absorb less calories. People who have surgery are usually very obese. In Britain there are long waiting lists for this. It is very easy to get this surgery in Turkey. Seven Britons have died after having weight loss surgery there since 2019 and many more have had serious problems.
Some people think that obesity should not be treated at all. This position is contradicted by substantial medical research.
Weight loss medicines can make people want to eat less or make less of the energy from food be absorbed by their bodies. The only weight loss drug approved by the FDA for long term use is orlistat. The U.S. Food and Drug Administration has not approved other drugs because they have side effects. Also they are worried that people who are not obese will take them.

Societal views
In the West, people associate obesity with negative characteristics such as laziness, ugliness, stupidity, etc. Discriminating against someone because of their weight is legal in the United States. The fat acceptance movement says that this is wrong and is a kind of prejudice called fatphobia. In some cultures, obesity is viewed as positive. To those cultures, obesity is associated with wealth, beauty, and fertility.
Related pages
 Abdominal obesity
 Hypertrophy
 Healthy lifestyle
 Bariatrics (the part of medicine that deals with obesity)

References 

 
Physiques
Rn or RN could mean:
Radon, a gas that is a basic chemical element
Registered nurse, a nursing specialist in the medical field
Royal Navy,
Phillips Academy (also called Andover, Phillips Andover, or  PA) is a high school for boys and girls in Andover, Massachusetts, near Boston, USA.  The school is a boarding school.  75% of the students live there.

Phillips Academy is one of the oldest private boarding schools in the United States.  Two American Presidents, George H. W. Bush and George W. Bush, went to school there.

Phillips Academy was founded during the American Revolution as an all-boys school in 1778.  The great seal of the school was designed by Paul Revere. George Washington's nephews went to the school, and he once spoke at an assembly while visiting. John Hancock, the famous signer of the United States Declaration of Independence, signed the articles of incorporation.
Phillips Exeter Academy was made three years later in Exeter, New Hampshire by Samuel Phillips' uncle John.  The football teams have played against each other almost every year since 1878.  This makes their rilvalry one of the oldest high school rivalries in the country.

Paul Revere put bees, a beehive, and the sun into the school's great seal.  The school's main motto, Finis Origine Pendet, means "the end depends upon the beginning." It is written at the bottom of the seal. The school's second motto, Non Sibi means "not for self."  

Schools in Massachusetts
1778 establishments in the United States
18th-century establishments in Massachusetts
Gluttony is a wasting of resources. Usually it is food that is wasted. Either one person eats too much, or the person does something so the food (or the resources) do not reach those who need it.

In Christianity, this is considered to be one of the Seven deadly sins.

Seven deadly sins
Greed is a desire to have more goods, or more wealth than is needed. Christianity says that greed is one of the Seven deadly sins. There it is listed as avarice, or in Latin avaritia.

Emotions
Seven deadly sins

nl:Hoofdzonde#Avaritia
"Mazurek Dąbrowskiego" (, meaning "Dąbrowski's Mazurka") is the national anthem of Poland. It is commonly called "Poland is Not Yet Lost" in English. The words of the song were written in 1797 by a Polish nobleman named Józef Wybicki. Kazimierz Sikorski rearranged the song's music, though the original composer is not known. It was officially adopted as the country's national anthem in 1927.

Lyrics

Current version

Original version

Other websites 
  "Mazurek Dąbrowskiego" in Mp3 format  (Full version)
  "Mazurek Dąbrowskiego" in Mp3 format  (Instrumental version)

References 

 
1797 establishments
1790s songs
National symbols of Poland
CSA can mean the Confederate States of America.
 CSA was Czechoslovak State Airlines (now called Czech Airlines)
Fornication is a word that means having sex with someone who is not your spouse. Many Christians and Muslims believe it is sinful.

Sexual acts
Religious ethics
Profit is how much money somebody (normally a company) makes. This is found by subtracting how much money they have spent (expenditure) from how much money they have brought in (revenue).

An example
If John spends $15 on some ice cream cones, and then sells them for $20, he has made a profit of $5. This is because he made $20 but when the $15 he used to buy the ice cream cones is subtracted, what is left is $5. In the end, he has $5 more than he had before he bought and sold the ice cream cones.

Money
Income
Roasting is a way of cooking. Something gets roasted if it is put over a fire, and some is burnt. The same effect can also be attained with a grill at a barbecue.

Meat 

In different countries people like to roast different things.  People usually roast meats such as pork, beef, chicken, lamb, and duck. The roasted meat, along with its accompanying vegetables, is often called a roast.

Most meat being roasted has to cook for a relatively long time, to ensure that it is cooked through.  Variations to this include lamb and beef, which may be left "pink" or partially uncooked towards the centre.

Other 
Other things can be roasted too. For example, vegetables, coffee and chocolate. Coffee and chocolate are always roasted.

Cooking methods
Influenza, better known as the flu and sometimes called the grippe, is a common childhood illness, but is not as common among adults. It is not limited to humans, most mammals and many birds can also catch influenza. It is caused by several different viruses, termed influenza viruses A, B, C, and D.

Flu transmission and symptoms 
Human influenza can pass from one person to another very easily. It is most commonly spread by the microscopic droplets of mucus and fluid that are sent into the air when the sick person coughs or sneezes. Symptoms include cough, sore throat, muscle aches and pains, fever, headache, and rarely vomiting and diarrhea.  Influenza can also lead to other diseases, such as pneumonia. This makes it especially dangerous to young children and elderly people.
Although there is no cure for influenza, antiviral drugs can be used to treat the illness so it is not as severe and does not last as long. Influenza vaccines are available worldwide, and are quite effective. They are changed each year as the virus changes.

The  influenza  season runs from late fall to spring because most people catch it in the winter months. When there are more cases of influenza than expected, it will sometimes be called an epidemic. When there are a large number of cases of the same type of influenza all over the world, it is often called a pandemic.

History 
The virus is ancient. It has infected humans for centuries.

Changes in the influenza virus 
Small changes that happen as flu is passed from one person to another is the most common way flu viruses change. This is the main reason that people can catch the flu every year.
The CDC keeps track of the different flu viruses that are circulating, and gives this information to the companies that make flu "shots". Since the flu changes so much from year to year, flu shots have to be given each new flu season.

Flu shots only protect against the most common flu viruses, and every now and then a slightly different type spreads more than expected. Usually when this happens, the existing flu shot gives some protection so that even if a person who had a flu shot catches it, they do not get as sick.

Some flu viruses are caught from animals. Bird flu, for example, is usually only caught by people in contact with sick birds (usually chickens). These types of flu virus are usually very limited, and while they can make a person very ill, usually other people do not catch the virus from the sick person.
Another way that the flu can change is when a person or animal catches two different flu viruses. The two viruses can exchange some of their genetic information, which can create a brand new flu that nobody has ever caught before.

If an animal flu virus changes in this way to one that can easily pass from human to human, many people become ill because nobody has any immunity to the new virus. Often, a brand new virus is more severe and kills more people.

New types of flu virus are usually what causes pandemics, and that is the reason many scientists have been following bird flu so closely—it kills six people out of every ten who catch it. This would be a very serious problem if it changes enough to spread easily between people.
Swine flu (March/April 2009)  
This new flu virus got its name because it contains genetic parts that are commonly found in flu viruses that infect pigs. It is not spread by pigs or by eating pork—this is a new human virus being spread by humans. The name was the 2009 flu pandemic.

References

Other websites 
 CDC info on influenza
 World Health Organization Fact Sheet Overview of influenza.
 NHS Direct Health encyclopedia entry 
 Both overview and technical details on influenza viruses with emphasis on the potential H5N1 pandemic Includes details of various nonhuman influenza viruses. Extensive and well done.
 Another overview of influenza

Pulmonology
Diseases caused by viruses
The pancreas is an organ that makes hormones and enzymes to help digestion. The pancreas helps break down carbohydrates, fats, and proteins. The pancreas is behind the stomach and is on the left side of the human body.

The part of the pancreas that makes hormones is called the Islets of Langerhans. The Islets of Langerhans are a small part (2%) of the total cells in the pancreas.  The Islets of Langerhans change which chemical they make depending on how much of other chemicals are already in the blood.  So, the pancreas works to keep the level of chemicals in balance in the body.  If the Islets of Langerhans stop working, a person will suffer from a disease called diabetes. Doctors are experimenting with taking the Islets of Langerhans cells from a donor body and putting them into the pancreas of a person with diabetes to make that person well.

The pancreas belongs to two systems of the body: the digestive system for its role in breaking down nutrients, and the endocrine system for producing hormones.
Hormones 
The pancreas releases these hormones:
 Insulin (which decreases the amount of glucose or sugar in the blood)
 Glucagon (which increases the amount of glucose in the blood)
 Somatostatin (which reduces production of insulin and glucagon)

Digestive enzymes 
The pancreas releases many different enzymes to help digestion:
 Lipase (which breaks down fats)
 Amylase (which breaks down carbohydrates)
 Trypsinogen and Chymotrypsin (which break down proteins)
 Erepsin, which digests peptones into amino acids.

References

Other websites 

 Pancreatic Cancer Info 

Anatomy of the digestive system
A chloroplast is a small organelle inside the cells of plants and algae. They absorb light to make sugar in a process called photosynthesis. The sugar can be stored in the form of starch. 

Chloroplasts contain the molecule chlorophyll, which absorbs sunlight for photosynthesis. In addition to chlorophyll, a chloroplast uses carbon dioxide (CO2) and water (H2O) to form sugar and gives off oxygen (O2). 

Chlorophyll is what gives green plants their green colour. Chloroplasts also contain various yellow and orange pigments to assist in photon capture for photosynthesis.

Structure 
Each chloroplast is surrounded by a double walled semi-permeable membrane. These are collectively known as peristromia. In the layered stacks are flat disk-shaped thylakoids. They contain light-absorbing pigments, including chlorophyll and carotenoids, as well as proteins which bind the pigments. Like mitochondria, chloroplasts also contain their own DNA and ribosomes.
Evolution 
Chloroplasts are one of the many different types of organelles in the cell. They may have originated as endosymbiotic cyanobacteria. This was suggested by Konstantin Mereschkowski in 1905, after an observation by Schimper in 1883 that chloroplasts closely resembled cyanobacteria. 

Almost all chloroplasts are thought to derive directly or indirectly from a single endosymbiotic event. 

Mitochondria also had a similar origin, but chloroplasts are found only in plants and protists. In green plants, chloroplasts are surrounded by two lipid-bilayer membranes. They may be the outer and inner membranes of the ancestral cyanobacterium. Chloroplasts have their own genome, much smaller than that of free-living cyanobacteria. The DNA which remains shows clear similarities with the cyanobacterial genome. 

Plastids may contain 60–100 genes whereas cyanobacteria often contain more than 1500 genes. Many of the missing genes are encoded in the nuclear genome of the host.
In some algae (such as the heterokonts), chloroplasts seem to have evolved through a secondary event of endosymbiosis, in which a eukaryotic cell engulfed a second eukaryotic cell containing chloroplasts. This formed chloroplasts with three or four membrane layers. In some cases, such secondary endosymbionts may have themselves been engulfed by still other eukaryotes, so forming tertiary endosymbionts. In the alga Chlorella, there is only one chloroplast, which is bell-shaped.

In some groups of mixotrophic protists such as the dinoflagellates and some sea slugs, chloroplasts are separated from a captured alga or diatom and used temporarily. These klepto (stolen) chloroplasts may only have a lifetime of a few days and are then replaced.

References 

Organelles
Chlorophyll is a pigment that gives plants their green colour. Chlorophyll is a chemical in the chloroplasts of plants. It allows plants to absorb and use light. Energy from the light is used in photosynthesis to make glucose. This contains lots of stored energy which the plant needs to release. It does this through respiration. This energy is then used when the plant grows or repairs damage. Chlorophyll also makes the stem and leaf of the plant green.

Chlorophyll is a green pigment in almost all plants, algae, and cyanobacteria. It absorbs light most strongly in the blue portion of the electromagnetic spectrum, followed by the red portion. However, it is a poor absorber of green and near-green portions of the spectrum. Chlorophyll was first isolated in 1817.

Chlorophyll and photosynthesis 
Chlorophyll is necessary for photosynthesis, which allows plants to obtain energy from light.
Chlorophyll molecules are arranged in and around the membranes of chloroplasts. It serves two main functions. The function of most chlorophyll (up to several hundred molecules per photosystem) is to absorb light and transfer that light energy to reaction centres. These pigments are named after the wavelength (in nanometers) of their red-peak absorption maximum. These chlorophyll pigments can be separated in a simple paper chromatography experiment.

The function of the reaction center chlorophyll is to use the energy transferred to it from the other chlorophyll pigments to undergo a specific redox reaction. In this reaction the chlorophyll gives an electron to an electron transport chain. This reaction is how photosynthetic organisms such as plants produce O2 gas, and is the source for practically all the O2 in Earth's atmosphere. Photosystem I typically works in series with Photosystem II.
The electron flow produced by the reaction center chlorophyll pigments is used to shuttle H+ ions across the membrane, setting up a chemiosmotic potential used mainly to produce ATP chemical energy; and those electrons ultimately reduce NADP+ to NADPH, a universal reductant used to reduce CO2 into sugars as well as for other biosynthetic reductions.

A green sea slug, Elysia chlorotica, has been found to use the chlorophyll it has eaten to perform photosynthesis for itself. This process is known as kleptoplasty, and no other animal has been found to have this ability.

Why green and not black?
Shil DasSarma, a microbial geneticist at the University of Maryland, has pointed out that species of archaea use another light-absorbing molecule, retinal, to get power from the green spectrum. Some scientists believe that green-light-absorbing archae were once the most common in the earth environment. This could have left open a "niche" for green organisms which would absorb the other wavelengths of sunlight. This is just a possibility, and Berman wrote that scientists are still not convinced of any one explanation.

Chemical structure
Chlorophyll is a chlorin pigment, which is structurally similar to and produced through the same metabolic pathway as other porphyrin pigments such as haem. At the center of the chlorin ring is a magnesium ion. For the structures depicted in this article, some of the ligands attached to the Mg2+ center are omitted for clarity. The chlorin ring can have several different side chains, usually including a long phytol chain. There are a few different forms that occur naturally, but the most widely distributed form in terrestrial plants is chlorophyll a. The general structure of chlorophyll a was worked out by Hans Fischer in 1940. By 1960, when most of the stereochemistry of chlorophyll a was known, Robert Burns Woodward published a total synthesis of the molecule. In 1967, the last remaining stereochemical elucidation was completed by Ian Fleming, and in 1990 Woodward and co-authors published an updated synthesis
. In 2010, a near-infrared-light photosynthetic pigment called chlorophyll f might have been discovered in cyanobacteria and other oxygenic microorganisms that form stromatolites.
The different structures of chlorophyll are summarized below:

Measuring chlorophyll 
Chlorophyll Content meters measure the optical absorption of a leaf to estimate its chlorophyll content. Chlorophyll molecules absorb in the blue and red bands, but not the green and infra-red bands. Chlorophyll content meters measure the amount of absorption at the red band to estimate the amount of chlorophyll present in the leaf. To compensate for varying leaf thickness, Chlorophyll Meters also measure absorption at the infrared band which is not significantly affected by chlorophyll.
The chlorophyll content of leaves can be non-destructively measured using hand-held, battery-powered meters. The measurements made by these devices are simple, quick and relatively inexpensive. They now have large data storage capacity, averaging and graphical displays.

Spectrophotometry
Spectrophotometry 

Measurement of the absorption of light is complicated by the solvent used to extract it from plant material, which affects the values obtained,
 In diethyl ether, chlorophyll a has approximate absorbance maxima of 428 nm and 660 nm, while chlorophyll b has approximate maxima of 453 nm and 642 nm.
 The absorption peak of chlorophyll a is at 666 nm.

Biosynthesis
In Angiosperms, the last step in the synthesis of chlorophyll is light-dependent. Such plants are pale (etiolated) if grown in the darkness. Non-vascular plants and green algae have an additional light-independent enzyme and grow green in the darkness instead.
Chlorosis is a condition in which leaves do not make enough chlorophyll, so they become yellow. Chlorosis can be caused by a not having enough iron—called iron chlorosis—or by not having enough magnesium or nitrogen. Soil pH sometimes affects these kinds of chlorosis. Many plants are adapted to grow in soils with specific pH levels and their ability to absorb nutrients from the soil can depend on this. Chlorosis can also be caused by pathogens including viruses, bacteria and fungal infections, or sap-sucking insects.

Related pages
 Xanthophyll

References 

Molecular biology
Pigments
Nitrogen compounds
Organic compounds
Photosynthesis
Plant anatomy
The oak tree is a tree or shrub in the genus Quercus. There are about 500 living species. They are divided into subgenera. The common name "oak" may also appear in the names of species in related genera, such as Lithocarpus.

Oaks have spirally arranged leaves, with rounded edges in many species; some have leaves with jagged edges or entire leaves with smooth margins. Many deciduous species do not drop dead leaves until the next Spring. In Spring, a single oak tree produces both male flowers (as catkins) and small female flowers. The fruit is a nut called an acorn, carried in a cup-like structure. Each acorn has one seed (rarely two or three) and takes 6–18 months to mature, depending on species. The so-called "live oaks" are evergreen. They are not a taxonomic group, just a life style which occurs in the genus.
The oak is a kind of hardwood forest tree. They are well known as a climax vegetation in the temperate zone of the northern hemisphere. That means, left untouched by humans, it would be the dominant tree. Much of England was covered by oak forests before modern farming took over the land. The last extensive oak woodlands were cut down to build ships for the Royal Navy in the 18th century.

Some kinds of oak wood are very hard. That is why people in past centuries cut them down to make ships, furniture and other things. The wood is now scarce and expensive and only used to make a few things anymore. Much cheaper are softwoods like pine.

Oak trees grow slowly and can live up to 1000 years.
Associated animals 
A mature oak tree stands about 100 feet tall (~30 metres). It is a home for more animals than any other European tree. 30 species of birds, 45 different bugs and over 200 species of moth have been found on oaks. Beetles burrow under the bark, and some drill holes into the wood. The leaves are eaten by many caterpillars. Many leaves carry strange little bumps on the underside. These are insect galls, caused by many little animals. Midges, moths, worms and tiny wasps lay their eggs in leaves or leaf buds. The leaf reacts by forming a growth around the eggs. Inside the gall, larvae develop. The leaf falls, but the larvae may come out only the next spring. Small galls only have one larva, but larger galls may contain as many as 30 larvae.

Acorns 

Oak trees produce acorns once a year which ripen in autumn. Oak trees may start producing acorns when they are about 20 years old. A mature oak may produce 90,000 acorns a year; this is several millions in its lifetime.

Related pages 
 Cork oak
References 

Trees
Fagales