text:
Perl Programming/Strings

Strings
Any sequence of characters put together as one unit, is a string. So, the word the is a string. This sentence is a string. Even this entire paragraph is a string. In fact, you could consider the text of this entire book as one string.

Strings can be of any length and can contain any characters, numbers, punctuation, special characters (like ! #, and %), and even characters in natural languages besides English. In addition, a string can contain special whitespace formatting characters like newline, tab, and the bell character. We will discuss special characters more later on. For now, we will begin our consideration of strings by considering how to insert literal strings into a Perl program.

To begin our discussion of strings in Perl, we will consider how to work with string literals in Perl. The word literal here refers to the fact that these are used when you want to type a string directly to Perl. This can be contrasted with storing a string in a variable.

Any string literal can be used as an expression. We will find this useful when we want to store string literals in variables. However, for now, we will simply consider the different types of string literals that one can make in Perl. Later, we will learn how to assign these string literals to variables in the Scalar Variables section.

Single-quoted strings
String literals can be represented in primarily three ways in Perl. We have already used one type in the simple programming examples, using double quote marks. Using double or single quote marks in Perl each has a special meaning.

Single quotes can be thought of as literal strings. In the previous examples, you may have noticed that variable names were included inside the strings with double quotes. When the results were printed, the value of the variable was placed in the printed line, not the name of the variable. If single quote marks were used, the actual variable name would have been printed because nearly all special characters that might be interpreted differently are taken at face value when using single quotes.

To see what is meant by this, try this simple program:

You should see "Hello Fred" on the first line and "Hello $name\n" on the second (without a newline after it). Putting the value of $name into the string in the first print statement is called "interpolation." If you don't need interpolation, you should use single quotes, because it makes your intent clearer.

Special characters in single-quoted strings
There are two characters in single quoted strings that do not always represent themselves. This is due to necessity, since single-quoted strings start and end with the ' character. We need a way to express inside a single-quoted string that we want the string to contain a ' character.

The solution to this problem is to preceded any ' characters we actually want to appear in the string itself with the backslash (\ character). Thus we have strings like this:

We have in this example a string with seven characters exactly. Namely, this is the string: xxx'xxx. It can be difficult at first to become accustomed to the idea that two characters in the input to Perl actually produce only one character in the string itself. (C programmers are already probably used to this idea.) However, just keep in mind the rules and you will probably get used to them quickly.

Since we have used the \ character to do something special with the <tt>'</tt> character, we must now worry about the special cases for the backslash character itself. When we see a <tt>\</tt> character in a single-quoted string, we must carefully consider what will happen.

Under most circumstances, when a <tt>\</tt> is in a single-quoted string, it is simply a backslash, representing itself, as most other characters do. However, the following exceptions apply:

 * The sequence <tt>\'</tt> yields the character <tt>'</tt> in the actual string. (This is the exception we already discussed above).
 * The sequence <tt>\\</tt> yields the character <tt>\</tt> in the actual string. In other words, two backslashes right next to each other actually yield only one backslash.
 * A backslash, by itself, cannot be placed at the end of a the single-quoted string. This cannot happen because Perl will think that you are using the <tt>\</tt> to escape the closing <tt>'</tt>.

The following examples exemplify the various exceptions, and use them properly:

In the last example, note that the resulting string is <tt>Three \'s: "\\\"</tt>. If you can follow that example, you have definitely mastered how single-quoted strings work!

Instead of unreadable backslash escapes, Perl offers other ways of quoting strings. The first example above could be written as:

Newlines in single-quoted strings
Note that there is no rule against having a single-quoted string span several lines. When you do this, the string has newline characters embedded in it.

A newline character is a special ASCII character that indicates that a new line should be started. In a text editor, or when printing output to the screen, this usually indicates that the cursor should move from the end of the current line to the first position on the line following it.

Since Perl permits the placement of these newline characters directly into single quoted strings, we are permitted to do the following:

This string has a total of twenty characters. The first seven are <tt>Time to</tt>. The next character following that is a newline. Then, the eleven characters, <tt>start anew.</tt> follow. Note again that this is one string, with a newline as its eighth character.

Further, note that we are not permitted to put a comment in the middle of the string, even though we are usually allowed to place a <tt>#</tt> anywhere on the line and have the rest of the line be a comment. We cannot do this here, since we have yet to terminate our single-quoted string with a <tt>'</tt>, and thus, any <tt>#</tt> character and comment following it would actually become part of the single-quoted string! Remember that single-quotes strings are delimited by <tt>'</tt> at the beginning, and <tt>'</tt> at the end, and everything in between is considered part of the string, included newlines, <tt>#</tt> characters and anything else.

Examples of invalid single-quoted strings
In finishing our discussion of singled-quoted strings, consider these examples of strings that are not legal because they violate the exceptions we talked about above:

Sometimes, when you have invalid string literals such as in the example above, the error message that Perl gives is not particularly intuitive. However, when you see error messages such as:

(Might be a runaway multi-line '' string starting on line X) Bareword found where operator expected Bareword "foo" not allowed while "strict subs" in use

It is often an indication that you have runaway or invalid strings. Keep an eye out for these problems. Chances are, you will forget and violate one of the rules for single-quoted strings eventually, and then need to determine why you are unable to run your Perl program.

Brief digression from strings alone: The <tt>print</tt> function
Before we move on to our consideration of double-quoted strings, it is necessary to first consider a small digression. We know how to represent strings in Perl, but, as you may have noticed, the examples we have given thus far do not do anything interesting. If you try placing the statements that we listed as examples in Single Quoted Strings, into a full Perl program, like this:

#!/usr/bin/perl

use strict; use warnings;

'Three \\\'s: "\\\\\"'; # There are three \ chars between "" 'xxx\'xxx';            # xxx, a single-quote character, and then xxx 'Time to start anew.';

you probably noticed that nothing of interest happens. Perl gladly runs this program, but it produces no output.

Thus, to begin to work with strings in Perl beyond simple hypothetical considerations, we need a way to have Perl display our strings for us. The canonical way of accomplishing this in Perl is to use the <tt>print</tt> function.

The <tt>print</tt> function in Perl can be used in a variety of ways. The simplest form is to use the statement <tt>print STRING;</tt>, where <tt>STRING</tt> is any valid Perl string.

So, to reconsider our examples, instead of simply listing the strings, we could instead print each one out:

#!/usr/bin/perl

use strict; use warnings;

print 'Three \\\'s: "\\\\\"'; # Print first string print 'xxx\'xxx';            # Print the second print 'Time to start anew. ';   # Print last string, with a newline at the end

This program will produce output. When run, the output goes to what is called the standard output. This is usually the terminal, console or window in which you run the Perl program. In the case of the program above, the output to the standard output is as follows:

Three \'s: "\\\"xxx'xxxTime to start anew.

Note that a newline is required to break up the lines. Thus, you need to put a newline at the end of every valid string if you want your string to be the last thing on that line in the output.

Note that it is particularly important to put a newline on the end of the last string of your output. If you do not, often times, the command prompt for the command interpreter that you are using may run together with your last line of output, and this can be very disorienting. So, always remember to place a newline at the end of each line, particularly on your last line of output.

Finally, you may have noticed that formatting your code with newlines in the middle of single-quoted strings hurts readability. Since you are inside a single-quoted string, you cannot change the format of the continued lines within the print statement, nor put comments at the ends of those lines because that would insert data into your single-quoted strings. To handle newlines more elegantly, you should use double-quoted strings, which are the topic of the next section.

Double-quoted strings
Double-quoted strings are another way of representing scalar string literals in Perl. Like single-quoted strings, you place a group of ASCII characters between two delimiters (in this case, our delimiter is <tt>"</tt>). However, something called interpolation happens when you use a double-quoted string.

Interpolation in double-quoted strings
Interpolation is a special process whereby certain special strings written in ASCII are replaced by something different. In Single-quoted strings section, we noted that certain sequences in single-quoted strings (namely, <tt>\\</tt> and <tt>\'</tt>) were treated differently - these are called backslash escape sequences. This is very similar to what happens with interpolation.

For example, in interpolated double-quoted strings, various sequences preceded by a <tt>\</tt> character act differently according to the chart below:

As you may have noticed in the previous chapter, you can put the name of a variable within a string with its leading dollar sign. This form of interpolation replaces the name of the variable in the string with the content of the variable.

Examples of interpolation
Let us consider an example that uses a few of these characters:

#!/usr/bin/perl

use strict; use warnings;

print "A backslash: \\\n"; print "Tab follows:\tover here\n"; print "Ring! \a\n"; print "Please pay someone\@example.org \$20.\n";

This program, when run, produces the following output on the screen:

A backslash: \ Tab follows:	over here Ring! Please pay someone@example.org $20.

In addition, when running, you should hear the computer beep. That is the output of the <tt>\a</tt> character, which you cannot see on the screen. However, you should be able to hear it.

Notice that the <tt>\n</tt> character ends a line. <tt>\n</tt> should always be used to end a line. Those students familiar with the C language will be used to using this sequence to mean newline. When writing Perl, the word newline and the <tt>\n</tt> character are roughly synonymous.

String operators
Operators manipulate two or more strings in some way.

The concatenation operator
Perl uses the <tt>.</tt> operator to concatenate or connect two strings together, like this:

"Hello". "World" # This is the same as "HelloWorld"

If you want to make the string have a space between Hello and World you could write it like this:

"Hello". ", " . "World" # This is the same as "Hello, World"

Or like this:

"Hello". ", World" # This is the same as "Hello, World"

The <tt>x</tt> operator
This is called the string repetition operator and is used to repeat a string. All you have to do is put a string on the left side of the <tt>x</tt> and a number on the right side. Like this:

"Hello" x 5 # This is the same as "HelloHelloHelloHelloHello"

If you wish to insert a line break after each output of the string, use:

"Hello\n" x 5

Exercises

 * Write a program that uses the <tt>.</tt> operator to print "Hello, Sir!".

 * Write another program which uses the <tt>x</tt> operator to print "HelloHelloHelloHello". Put comments in this program that explain how it works

 * Remember to take some time to play with single and double quoted strings, the more practice you get, the better you will be.

Perl/Strings

title: Perl Programming/Strings


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World History/Operation: Blank Check

Operation: Blank Check is the title of the current stage of development for World History. The scope of this portion is divided into two major categories, as follows:

 * Finalization of structure
 * Basic articles in place (See: The Rise of Dictatorship and Totalitarianism)

Finalization of structure
This goal encompasses the final chapter listing (World History) and the structure of the articles themselves. Currently, there are 32 chapters. The scope of World History indicates that there will be more, probably at least 5, especially since one of the goals is to include little-known parts of history, like the Kush Empire (near India, no relation to the one south of Egypt) and the Parthian Empire. Also, more mainly, there are a few gaps in the history chain; the one between the Industrial Revolution and World War I is the most prominent. At this time however, we hope to concentrate on the 30 we have down. On the main page, each will have a brief summary, such as already exists for several. Eventually the broad date of the topic will be added to the summary. In naming, chapter titles should have any important words capitalized. Note the differences to this convention in Internal Article Structure (IAS).

Internal Article Structure (IAS)
IAS is in full swing at this point. It has been applied to several articles and is still evolving, and therefore varies slightly from article to article. For instance, see the Ancient Civilizations structure versus that in The Rise of Dictatorship and Totalitarianism. There are subtle differences. Because the latter article is almost complete, dates have been added to the subtitles and structural denotations in this article already. We hope to have a brief timeline someday to help expedite the dating process. IAS stipulates the following:

Each article is broken down into broad categories (see Precolumbian History of the Americas for an example) which are further divided into individual cultures/civilizations/events. Structure is to follow this basic method: 1)If the topic is better done by region, such as in the Americas example, then the subcategories must correlate to individual parts of that region, 2) If the topic is better done "by topic", such as in the Dictatorship example, then is is helpful to break the broad categories into time periods within it, such as the rise of Hitler. Also, when a single person has an inordinate influence on an event and enough information is available, text should be devoted to the development of this individual's thought, such as early life, political philosophy, etc. (again, see the Dictatorship example), 3) Under no circumstances should there be any divisions smaller than second level (as in ===Title=== ). Namewise, make sure that only the first word and the proper words are capitalized if possible.  It's odd, but in main chapter titles, all words other than "the", "and", and the like being capitalized is pleasing, but not in article categories and subcategories.  Please try to stick to this especially.

So, the guidelines are broad, and much leeway is given. Please feel free to do a little experimenting, but try not to move things around too much that already have substantial topical information in them. Follow the Golden Rule and ' Have fun! '

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: World History/Operation: Blank Check


text:
Talk:World History Project - Contents/Archive 1

This structure is based entirely on the requirements for the CA book. Lord, if it doesnt look to be a boring book. Somehow I graduated from high school and college without knowing most of this stuff. --Karl WickI think that a textbook on world history should actually encompass more than the development of western government. Talk more about India, China and Africa for heaven's sake. I realize this outline is designed to meet California requirements but a comprehensive textbook on World History should be more representative.

Just have come across this. It's as biased as World History could be. IS there a world outside Europe and the USA? Makes me wonder...

I just haven't gotten around to writing about most of the world yet. As you can tell, I've started work on the Ancient World, WWI & WWII, Exploration, Ancient Mesoamerica, and Early China & Japan. That's alot of information already (because of some additional chapters, this may turn out to cover much more than the CA standard, and at least twice as long). Right now, the entire thing is map deficient (most of that stuff is copyrighted and ineligible for inclusion), date deficient (sorry, but right now I'm more concerned about adding info than dates), and grammar deficient (again, info over proofs). It's going to take time, so thanks for patience and help! --Tai

One most consider the way in which one World History is taught. For example AP World History, to not seem Euro-centric fixates on the concept of interactions between nations after European Ex & Dis. this is in contrast to what World History once was where you would get a fairly indepth look at Mesopotamia then India, China, perhaps Mesoamerica and then to greece and rome and continue on with Europe for the rest of the year. My Pre-AP World History class was done like that but we stopped at the Renaissance in preperation for AP European History, which starts a few hundred years before the Renaissance. When I was offered the chance to take AP World History, I quickly discovered that although the education I received in World History was excellent, I was lacking in anything after the Renaissance for anywhere other then Europe. A good example of this method of history can be found in Spielvogel's World History: A Human Odessey. Speilvogel heavily emphasis Europe and "western" civilizations after a certain point, with one or two chapters here and there covering broad topics in non-western civilizations. Eurocentricism is a large component of history education and one needs to find a way to not babble on incoherently about the "East" in an attempt to make it seem like there is more there then there actually is, while not taking the imperialist concept of "The White Man's Burden" to bring civilization to those eastern savages. The College Boards method is affective, but it does take some of the fun out of history because you center on interactions and trade rather then events and figures. --Alexbl 02:37, 25 Jun 2004 (UTC)

Personally, interactions and trade is the way to go for me. Sure, we will need to know about Hannibal, Gengis Khan, Napoleon, or Bismark, but in most cases the impetus for the events they inspired are already there. For example, Germany was well on its way to unification before Bismark, with the Confederation of the Rhine and that economic thing of theirs. Bismark just cleverly got France and Austria out of the way so he could set up the German Empire, but I bet at the rate Prussia was going it could have annexed all the little German states eventually. Of course, studying their lives is far more interesting than looking at the "big picture", and it's very easy (and correct) to think of one "great leader" altering history. But conditions have to be right, too. I bet there were plenty of people wanting to set up a German Empire long before Bismark came around, and faileed because of the petty infighting between the Germanic royals (before all the fighting got to them). Just my 2 cents. --Tai (P.S., nice job on the European History book, it looks much more complete than this one).

This page is a little odd--it focuses in only on California standards, and the organization is also wierd. Simple little things like titles and headings are missing and/or not in the most gramatically correct english. Also, you can't just read from a book and summaraize and/or copy exactly down what you see, that's not only plagiarism, but 10th grade history books are meant to be understood by people with a huge range of IQs, and still developing minds. This page needs serious restructuring. Though, I do admire trying to adhere to a written set of standards.--Naryathegreat 23:52, 5 Nov 2004 (UTC)


text:
User:204.95.17.172

Stephanie Meakes
I'm Single, Smart, Sexy, What More Do You Want?

If You Want More Info About Me Than E-mail Me At:

Here's My Picture:

lover_girl303030@yahoo.com

Looking For Sexy Guys

title: User:204.95.17.172


text:
Wikijunior:South America/Brazil

Part of Wikijunior South America project

Bem-vindo ao Brasil—Welcome to Brazil! Brazil is by far the largest country in South America, and the fifth largest country in the world. Brazil is located right in the middle of South America, and borders most of the other countries, but it is also very different from them. For instance, while most people in South America speak Spanish, in Brazil people speak Portuguese. Brazil is home to 190 million people, who live in twenty-six states and one Federal District (the capital, Brasília). Because Brazil is so large, it is often broken up into five geographical regions; the North, the Northeast, the Southeast, the South, and the Center-West regions.

What are Brazil's national symbols?
Brazil's flag is green with a yellow rhombus and a blue circle set with stars.The stripe across it says ordem e progresso which means order and progress. Brazil's national colors, green and yellow, represent the colors of the royal Portuguese family. Brazil once had the largest gold mines in the world. The blue circle shows the sky over Rio de Janeiro.

What are some famous places in Brazil?
Brazil is home to the Amazon River and the Amazon Rainforest. It also has two of the 30 largest cities in the world, São Paulo and Rio de Janeiro.

The steamy rainforest of the Northern Region
The northern region of Brazil contains the Amazon, the world's largest rainforest. A rainforest is a place with lots of rain, animals, and trees. The rainforest is so big that it stretches into Brazil's neighbors—Colombia, Peru, Venezuela, Ecuador, Bolivia, Guyana, Suriname and French Guiana. In fact, the Amazon is so big that if you got all the rainforests in the rest of the world and put them all together it would not be as big as the Amazon. The Amazon Rainforest is named after the Amazon river which is the second longest river in the world.

Because the Amazon is a rainforest, life is very hot and wet. Many thousands of different types of animals and plants are found in the Amazon, as well as 2.5 million different insect species! Because the Amazon is so big, there are still some animals and plants that haven't even been discovered yet.

Unfortunately, the Amazon Rainforest is very quickly shrinking to make way for farmland and cattle. Burning the rainforest is illegal, but difficult for the police to stop because the vastness of the Amazonian region and for the money into the black market that sells wood worldwide... The burning of the forest means that many animals and plants are becoming extinct. Although lots of people are very worried about this it is unlikely that the destruction of the forest will end in the near future.

The beautiful beaches and festivals of the Northeast
One beautiful beach in the Northeastern area. This is Boa Viagem Beach. The northeastern region was the first part of Brazil to be inhabited by Europeans, and is sometimes called the heart of Brazil. Some of the oldest cities in the country are there, especially on the coast. The area's beautiful shores attract people from every part of the world. Salvador and Fortaleza are typical cities of the northeastern region. In Salvador the people have invented many dances and musical rhymes for the many festivals which are held year round.  Carnival A Carnival is a public parade, combining some elements of a circus and public street party. Carnival is a Catholic tradition, and is celebrated throughout most of South America, but is biggest and most famous in Brazil, especially in Rio de Janeiro. The celebrations start forty days before Easter, and run for four days. Every region celebrates Carnival in a different way. In Salvador many thousands of people cram the streets to listen to and dance to the trios elétricos. Trios elétricos are giant trucks with a band playing on. In Rio de Janeiro there are Escolas de Samba, which means "Samba schools" – but in these schools the people don't learn to samba, they work all year preparing a big show like an opera: the Samba Schools Parade. In Recife and Olinda, people go to streets to follow the frevo and maracatu bands like the Galo da Madrugada (Rooster of the Dawn), the largest Carnival group in the world.

The grand cities of the Southeastern Region

Southeast Brazil is the part of the country that has the most people and the most business. It contains the two famous Brazilian cities: Rio de Janeiro and São Paulo. São Paulo is Brazil's biggest city and has over 20 million people living in it. People living in São Paulo are called Paulistanos. Rio de Janeiro is also a very big city but not as big as São Paulo, with only 10 million inhabitants. The people who live in Rio (called Cariocas) are very proud of their city because it is so beautiful. Rio de Janeiro has some famous beaches, which have been mentioned in many songs and films. The city got its name (which means "January River" in Portuguese) because the city has a great bay; early Portuguese explorers discovered this bay in January and thought it was the mouth of a river, hence the name "January River."

The European-like Southern Region
The Southern Region is very different from the rest of Brazil. The temperature is much cooler, and many of the people who live there descended from people who came to Brazil from Italy, Germany, and other countries in Europe. In some cities people still speak the languages of those countries along with Portuguese. The gaúcho is a kind of cowboy from southern Brazil: he rides his horse through the Pampas, large fields of cattle breeding. Nowadays, however, a gaúcho (or gaúcha, if female) is anyone born in Rio Grande do Sul, regardless of living in the city or in the country.

The vast fields of the Center-West Region
The Center-West Region is the least populated region in Brazil. The large fields of Cerrado are the place for big plantations of soy and cattle breeding. In central-west Brazil we find Brazil's capital, Brasília, a city constructed in the middle of the last century with street patterns shaped like an airplane! Brasília is also located near the exact center of Brazil's territory. In the central-west area there is also the Pantanal, probably the largest wetlands in the world (it is about half the size of France), where a great range of different kinds of birds, fish, mammals, reptiles and others beings live.

What important events have happened in Brazil?
 Where does Brazil's name come from? When the first Portuguese arrived in Brazil, they called this land Ilha de Vera Cruz (Island of True Cross), because they thought Brazil was an island. When they discovered that Brazil wasn't an island, the Portuguese called it Terra de Santa Cruz (Land of Holy Cross). Finally, they found a tree there that could be used to paint clothes with red color. They called this tree pau-brasil, pau means wooden stick and brasil comes from brasa which means ember. So, Brazil received its name from the tree pau-brasil. Portuguese explorer Pedro Álvares Cabral arrived in Brazil in 1500, and called the land for Portugal. Today, the Brazilians are descendants from people of many regions of the world, mainly Portuguese, Africans, and from people the people who lived there when the Portuguese arrived, the Indians (índios). There were many Indians in Brazil in ancient times, but diseases and wars against foreigners reduced Indian populations. Millions of Africans came to Brazil as slaves to work mainly in sugar cane farms.

In 1808, King João VI of Portugal, fleeing Napoleon's French army, moved the seat of government to Brazil, and made Rio de Janeiro the temporary capital of Portugal. Even after the government officially moved back to Portugal, Rio de Janeiro was thought to be a co-capital of the empire for many years, and had a significant influence on the people of Portugal.

In 1822, Brazil declared its independence from Portugal, becoming the Empire of Brazil. And the Portuguese Prince-Regent (next in line to become king of Portugal) Pedro I became Brazil's Emperor. Later on, his son, Pedro II, was chosen the second Emperor. During these times Brazil had to fight wars against its neighbors, Argentina and Paraguay, to avoid any invasion.

In 1888, Princess Isabel ended the practice of slavery. Finally, in 1889, Brazil turned into a Republic, which meant Brazil now had a President who is elected by the people, instead of an Emperor.

From a small land bordering the Atlantic Ocean, Brazil grew to be an immense country, especially when some people found gold in Minas Gerais and Goias, far away from the coast, and when Brazil started to take latex from the Amazônia.

The capital of Brazil was earlier Rio de Janeiro, and stayed there for many years. After many attempts, a new capital was created and built near the center of Brazil called Brasília in 1956. This was done for many reasons, although a major purpose was to draw the population of Brazil away from the coastal cities and instead toward the interior of the country.

During the twentieth century, Brazil went twice under Dictatorships, which is a type of government that gets a lot of power and turns against the people. When under dictatorships, Brazilians that opposed the government experienced hard times of censorship and cruelty. Today Brazil is a free country, where people are able to vote for President and express themselves with no fear. In late 2010, Brazil elected its first female president, Dilma Rousseff, who took office in January 2011.

What is the natural environment like in Brazil?
Brazil may have more different types of animals than any other country in the world. This is because Brazil is such a large country with many different forests that are dense with living things. All of Brazil is warm and some of Brazil is very rainy. There are two huge forests in Brazil. The Amazon rainforest and the Atlantic forest. Both of these forests are shrinking because people cut the trees down for lumber and also to clear the land for farming and ranching.

What types of things are made in Brazil?
Brazil produces many types of things. There are iron mines that produce iron to make into steel. Brazilians also grow coffee, soybeans, and fruit. They manufacture airplanes and cars and electrical equipment. There is also a lot of tourism and eco-tourism in Brazil. (They are known for one of the countries making the most coffee in the world) Lately, Petrobras, Brazil's largest oil company is offshore drilling along the continental shelf, it is moving Brazil from being nearly 100 percent dependent on foreign oil imports toward becoming a net oil exporter in the next few years.

What is School like in Brazil?
School varies in Brazil, there are many excellent schools however they are private schools and cost a lot of money to go to. The ones that are public can be much worse. Because many people in Brazil aren't very rich, many children will not get to go to a good school.

What sports are popular in Brazil?

Soccer/Football is the most popular sport in Brazil - the country has won the football World Cup more times than any other country. Swimming and Volleyball are some other competitive sports that are played.

Who are some famous people from Brazil?
Some people from Brazil have become famous all over the world.

One of the best-known is Pelé, a soccer player that many people believe was the best ever. Ayrton Senna was a Brazilian three-times Formula One world champion. He won in 1988, 1990, 1991.

title: Wikijunior:South America/Brazil


text:
User:The bellman

G'day The bellman is a character from The Hunting of the Snark by Lewis Carroll. My real name is Robin Shannon and i live in Canberra, Australia. If you want to contact me by email or with jabber/gtalk you can do so by using FIRSTNAME@LASTNAME.net

sub pages
Cookbook

Proofreading

title: User:The bellman


text:
User talk:The bellman

'Note to anyone doing anti-spam patrol: Spammers seemed to love this page for some reason and so i protected it. I have now unprotected it to see how it goes, but if it gets spammed and you feel the urge to reprotect it then by all means protect it again. In such a case i am contactable at my wikipedia or wikinews talk pages, by email/jabber at FIRSTNAME@LASTNAME.id.au (my full name is robin shannon) or thru my website'

Redirects
Ah, now you understand some of the bad things about interwiki redirects. You need to manually construct a url with &redirect=no at the end in the browser address bar, in this case http://en.wikibooks.org/w/index.php?title=User:The_bellman&redirect=no. You'll also need to do it for your talk page at http://en.wikibooks.org/w/index.php?title=User_talk:The_bellman&redirect=no. Gentgeen 09:37, 21 Jan 2005 (UTC)
 * Of course, by posting this here, I've kinda taken care of that last item. Gentgeen 09:45, 21 Jan 2005 (UTC)
 * Coolies, thanks. The bellman 22:44, 23 Jan 2005 (UTC)

adminship
I would have promoted you to admin here, except that you withdrew your request (I almost decided to do it anyway, but didn't). Let me know if you are interested again, as we could use some more admins here. Even if all you do is some occasional vandal-blocking, it'd be good to have another admin around. TUF-KAT 16:37, 23 Apr 2005 (UTC)
 * I don't think there'll be any controversy about it since you had some support, so I went ahead and made you an admin. TUF-KAT 17:23, 24 Apr 2005 (UTC)

specific companies
If you want to eliminate specific companies from the Cookbook:Vegan cuisine page, you have lots more to go. The page is virtually a corporate ad page.

I myself am guilty of adding 1 or 2 links to corporate web sites and/or 1 or 2 product names. I've only done this for those that I thought were particularly deserving. I tend to thing that anon users and non-regular contributers should not be allowed to do this, because they might be getting paid to spam the wiki. If a regular cookbook contributer wants to do this though, I think we should trust that the recommendation is in good faith and is useful. AlbertCahalan 17:13, 25 Apr 2005 (UTC)

-- I added most of those companies (some while not logged in) for the express purpose of people being able to find vegan products. These could perhaps be split off to another page, but I think it's unreasonable to eliminate them. Vegan substitute products are difficult to find and it's even more difficult to find good ones. I am curious about your thoughts on this. Kellen
 * Please respond on the Talk:Cookbook:Vegan_cuisine page instead of here. Thanks! Kellen 17:42, 18 May 2005 (UTC)

Recentchanges
Sure... It's not protected though, so one need not be an admin to edit recent changes. TUF-KAT 21:13, 26 Apr 2005 (UTC)

HEAR YE, SPAMMERS!
WHY DOST THOU LOVE TEH_BELLMAN SO?! DEFILE HIS TALK PAGE NO LONGER! Kellen T 19:19, 26 August 2005 (UTC)

Your De-Adminship
Hello. I would like to inform you that you will have your sysop rights removed here on 1 Nov 2006 due to inactivity. If you would like to discuss the matter, please see WB:RFA. You can re-apply for adminship at a later date if you wish. Thanks. -within focus 21:31, 1 October 2006 (UTC)

title: User talk:The bellman


text:
Celestia/Add-Ons

Introduction
This article describes the most common procedures for installing add-ons for the 3D astronomical visualization program "Celestia". It can be downloaded for free from Celestia. Most add-ons designed for this program can be downloaded from the Celestia Motherlode or Forum. This document does NOT describe how to create new add-ons. If you want to make your own add-ons or modify others, you should start by reading Selden Ball's Not-so Brief Introduction to Add-ons For further information, also see the Documentation Page of the Motherlode.

If you are new to Celestia, please read this document from start to finish, since information that is relevant to later sections is covered in earlier ones. If you try to read just the section that you want help with right now, you might miss important information that would help with future problems.

How Celestia determines what to display
The Celestia application itself is a very small part of the package that you initially download. Most of the size of the package is due to the pictures and catalogs of the celestial objects that Celestia draws. When Celestia launches, it reads the data from a folder on your computer called "Celestia" (Windows systems) or "Celestia Resources" (Macs). It then uses that data to determine what to display. By editing a few files in this folder, you can change what Celestia displays on the screen.

The Celestia Resources folder is in different places depending on your operating system.

In Windows, by default it usually is located in C:\Program Files\ and is called "Celestia" (Double-click on My Computer to find it). However, the Celestia installation program will let you specify any directory you want. Windows is very protective of its Program Files directory, making it difficult to modify Celestia's files. Because of this, it's usually a good idea to specify some other directory.

In Mac OS X, the folder is called "CelestiaResources" and it will be where the person who installed the original Celestia program put it. This is usually in /Users/ /Library/Application Support/ or within the Celestia application bundle. To find it inside the bundle, hold down the {Ctrl} key, click on the Celestia icon and select "Show Package Contents" from the menu that appears.

In Linux KDE, the folder can be installed anywhere, although /opt/kde3/share/apps/celestia is the default and most likely place. In Ubuntu the directory is /usr/share/celestia.

Types of add-ons
Add-ons fall roughly into two broad classes: replacement textures and extras. Since their methods of installation are different, we will deal with them differently.

Replacement Textures
If the files you download are nothing more than images, you are dealing with a replacement texture. Celestia supports the following image formats: JPEG, PNG, DDS and BMP. (BMP images should be avoided. Celestia does not implement most of the BMP standard.)

An add-on containing replacement textures is designed to replace a texture that was included with the default distribution of Celestia that you downloaded. There are two ways to install new textures: by replacing the original image file, or by editing the catalog file that points to the texture, so that it points to your new image file instead.

Replacing the image file
Replacing the image file is simple. The tricky part is detailed in the note below about image resolutions.

Open the textures folder in the Celestia resources folder, find the image file that you want to replace, and remember or write down its exact name. Then rename the original file to something else, like -old.jpg. Place the new image file in the same folder as the old one, and re-name it so it matches the original name of the old image (paste the name from the clipboard.) When you relaunch Celestia, you should see the new texture in place of the old one.

Resolutions
Celestia allows you to provide images with the same name but with three different resolutions: low, medium and high. They are kept in the lores, medres and hires folders. You can type the letters "r" and "R" to switch among them. These resolution names are just for your convenience, though. There's otherwise nothing special about the images.

Texture images must be a power-of-two on a side: 512x256, 4096x2048, etc. This restriction is in the design of most 3D graphics cards.

Editing the catalog file to refer to your new Texture
Instead of renaming files as above, you can change the catalog file that directs Celestia to the image file you want to replace. For all default textures, these catalog files are in the folder "data" inside the main Celestia resources folder. They are called "ssc" catalog files, and they end in the 3-letter extension (ssc).

Based on the names of the files, find the one that describes the texture you want to replace. For safekeeping, copy the original catalog file to another name with a different filetype. Then open it with a text editor and scroll down until you see the entry for the object you are trying to improve. The syntax of the catalog file should be understandable. Replace the name of the old texture with the name of your new texture, but don't modify anything else. Save and close the catalog file.

Place your new texture in the medres folder inside the textures folder inside the Celestia Resources folder.

When you launch Celestia, you should see the new texture on the object whose catalog entry you edited.

Extras
Extras are add-ons which usually cause Celestia to display an object that is not present at all in the default distribution. They usually include several files including catalogs, models, textures, and, hopefully, a README that tells you what to do get the object to display properly. If there is a README included, follow its instructions to install the add-on. If there is no README, you will need to sort the add-on's files by their filetypes (the part of the name that is after the dot).

Place the files in the following directories (folders) according their filetypes:

 * .cmod or .3ds or .cms -- Place these models in the models directory.

 * .jpg or .png or .dsc or .bmp -- Place these pictures in the textures/medres directory.

 * .ssc or .stc or .dsc -- Place these catalogs in the add-on's main directory.

 * .xyz -- Place these trajectories in the data directory.

Testing the Add-on
After you have installed the add-on, you'll need to quit and relaunch Celestia. This is because Celestia only reads the data files when it is launched. Any changes you make will not be apparent until you start Celestia again.

If you are installing a new object in Celestia, visit the object by pressing the [Return] or [Enter] key to bring up the target entry prompt. As you begin to type the name of the object you want to visit, Celestia will try to guess what object you want. You can press the TAB key to cycle through Celestia's guesses. When the window displays the name you want, press [Return] (or [Enter]) again. If the object's name does not appear in the target entry window, you probably have not installed it correctly.

The object has now been selected. Press the 'g' key to go to it. Celestia's viewpoint should move toward the object and it should come into view. If the viewpoint changes but an object does not become visible, make sure that rendering for that object is enabled in the Rendering menu. If the proper rendering is enabled, but you still see nothing, it is possible that the object is not defined at the time that Celestia is simulating. This could occur with comet Shoemaker-Levy 9, for example, which crashed into Jupiter during July 1994. Celestia will still take you to a location for objects which no longer exist, but nothing will be displayed. To view the object, set the time to something more appropriate. For Shoemaker-Levy, this would be any date before July 18, 1994.

If you are installing a different texture for an object that already exists in Celestia, it might be defined in an SSC catalog as an AltTexture. To view such an alternate texture, right-click on the object and select the alternate texture from the popup menu. If you still have trouble getting your new add-on to work, you may want to read its ssc, stc or dsc catalog file for clues to how and where the object should appear in Celestia. Even the smallest error can cause Celestia to function incorrectly, so be careful.

Error messages often are shown in Celestia's "console log." Type a tilde (~) to toggle the log on and off. The up- and down-arrow keys can be used to navigate within it.

title: Celestia/Add-Ons


text:
Celestia/Versions

Celestia has gone through quite a few versions since it was first made available in the late 1990s. Some of the older versions are still available from SourceForge.

 * The next major release of Celestia, v1.7.0, is currently under development.
 * If the user interface changes to QT, which will be common to all operating systems, it may be called v2.0.
 * See the Development instructions if you'd like to try compiling the "pre-alpha" version yourself. It's very easy to do under Windows, at least.

 * Celestia v1.6.1 will be only a bug-fix release.
 * V1.6.1 has been delayed due to an intractable problem in the MacOS version.

 * Celestia v1.6.0 was made available on July 10, 2009.
 * Please visit the Celestia Web forum: Celestia 1.6.0 released for details.

 * Celestia v1.5.0 was made available on January 26, 2008.
 * Please visit the Celestia Web forum : Celestia 1.5.0 is ready for details.

 * The previous stable version of Celestia, v1.4.1, was released in February, 2006.

title: Celestia/Versions


text:
Introduction to Philosophy/Logic/Building More Complicated Formulas

Introduction to Philosophy > Logic > Building More Complicated Formulas

 * 'I need a hammer and nails or a screwdriver and screws.'

Though we know what is meant by the above statement, it is technically ambiguous - imagine saying it to a not very bright apprentice. In this case no harm would be done and the apprentice might fetch an unnecessary tool. One could think of other situations where such ambiguity could be lethal.

In propositional calculus we use brackets to prevent any ambiguity:

 * 'I need (a hammer and nails) or (a screwdriver and screws).'

This is just like the usual mathematical use of brackets: you evaluate the contents first.

We don't use brackets around ¬ symbols -- it binds tightly onto whatever is following it.


text:
Talk:Introduction to Philosophy/Logic/Building More Complicated Formulas

Does this make sense to anyone coming to the subject for the first time? I don't think I've written this brilliantly. Complete rewrites are invited.--publunch 12:11, 9 Nov 2004 (UTC)


text:
Talk:Introduction to Moral Reasoning/The dissertation

This sounded ok when I read it in French, but when I translated it into English, it suddenly sounds a little bit grand and wordy. Perhaps this is why a lot of English people have a problem with Derrida?? :) --publunch 12:34, 9 Nov 2004 (UTC)


text:
Talk:Supplemental Guide to Lord of the Flies

I've edited it: Move the parts to seperate pages if that is necessary (considering the amount of content) 193.63.168.228 14:50, 9 Nov 2004 (UTC)

General Question
It is a great debatable question as to how long the boys spent on this island. If anyone has any thoughts, or general guesses, please leave some here.

>>I don't know about how long. However, I do know that the story did not take place during WWI or II. The author's opinions and ideas may have stemmed from his experiences in WWII, but at the time of his writing LotF it was supposed to be futuristic.

>> I agree with the point made above. I would guess it was written shortly after the stories about WWII were told. Golding probably used these stories to help further his thoughts and ideas.

This is a great book Killershark101 (discuss • contribs) 21:28, 1 November 2016 (UTC)

Potential Copyright violation
User:Kernigh pointed out that the material on this page fails a google test. That may be true, but I'm thinking that instead of failing because the content was copyied from elsewhere, this is a failed test because many other sites are mirroring Wikibooks material and doing so illegally, unless they have also been granted copyright permission all of the users, including anonymous users (there are many for this Wikibook) who have contributed.

In short, by going over the history one edit at a time, I fail to see how this can possibly be a copyright violation by Wikibooks. Instead, it needs to be turned over to the Wikimedia legal team to have some real fun in terms of GFDL violations and other fun stuff that should be happening to people who abuse Wikibooks content.

Perhaps some minor content needs to be culled, but not this whole wikibook. --Rob Horning 03:11, 29 March 2006 (UTC)

 * On much futher review and really digging deep into the edit history, this edit is likely to be a copyright violation from an external source. Most of the rest of this Wikibook seems to have been generated a few sentances at a time, and typical of most Wikimedia development.  I'm surprised with how many people have subsequently visted this page havn't caught this earlier.  --Rob Horning 04:08, 29 March 2006 (UTC)

Lord of the Flies Quick Question
Who thinks that the prejudice in chapter 1 when Jack says to Piggy: "you're no good on a job like this" is important

chrisdabookreader 2k16

Chrisdabookreader (discuss • contribs) 18:10, 16 November 2016 (UTC)


text:
Management Strategy/Sustainable Competitive Advantage

In 1991, Jay Barney developed the Resource Based View of the firm. This view established four criteria that determine a firm's competitive capabilities in the marketplace.

These four criteria for judging a firm's resources are:
 * 1) Are they Valuable? (do they enable a firm to devise strategies that improve efficiency or effectiveness?)
 * 2) Are they Rare? (if many other firms possess it, then it is not rare)
 * 3) Are they Imperfectly Imitable? (because of unique historical conditions, causally ambiguous, and/or are socially complex)
 * 4) Are they Non-Substitutable? (if a ready substitute can be found, then this condition is not met)

When all four of these criteria are met, then a firm can be said to have a sustainable competitive advantage. In other words, the firm will have an advantage in the marketplace which will last until the criteria are no longer met completely. As a result, the firm will be able to earn higher profits than other firms with which it competes.


text:
User:Isomorphic

I'm an infrequent editor here on Wikibooks.

I've done a little work on the Wikijunior project, which is getting far too little attention considering that we got a grant to work on it. I started the Ecuador article for Wikijunior South America, but so far that's my only original content.

I'm mostly active on the English Wikipedia, and my main user page is there.

title: User:Isomorphic


text:
Celestia/Time Control

There are several keys that can be used to control the rate and direction of the passage of time.

title: Celestia/Time Control


text:
User talk:68.255.68.229

added new title

title: User talk:68.255.68.229


text:
User talk:271828

Welcome to my talk page. I'm not sure how often I will check it, so you should probably send me e-mail if you want to be sure I hear from you.

geometry book
we both seem to be working on the geometry book right now. i'd like to email you about it, but don't know your email. trying not to duplicate your work.

Pictures
As you can see at the top of this page, "All unlicensed images uploaded to wikibooks before November 1, 2006 will soon be deleted." You have uploaded images and some of them are untagged. You can see them here. Please review them and add appropriate tags. --Think Fast 04:33, 13 November 2006 (UTC)

title: User talk:271828


text:
User:鼠

 * 私は馬鹿です.
 * わたしはばかです.
 * Watashi ha baka desu.

 * Member of Jref.com forums.
 * Teaches people the basics of the Japanese language in a quick and mannerable fashion.
 * Passed JLPT 4 and 3.

 * I don't understand why Wiki wants everything so complex. It make a person need a high vocabulary list,
 * Edit the lessons I give all you want, just don't destroy the learning incline.

title: User:鼠


text:
Geometry/Introduction

Introduction to High School Geometry
The word geometry comes originally from Greek, meaning literally, to measure the earth. It is an ancient branch of mathematics, but its modern meaning depends largely on context.
 * To the elementary or middle school student (ages six to thirteen in the U.S. school system), geometry is the study of the names and properties of simple shapes (e.g., the defining properties of triangles, squares, rectangles, trapezoids, circles, prisms, etc., along with formulas for their areas or volumes).
 * To the high school student (ages fourteen to seventeen in the U.S. system), geometry has two flavors: synthetic and analytic. Synthetic geometry uses deductive proof to study the properties of points, lines, angles, triangles, circles, and other plane figures, roughly following the plan laid out by the Greek textbook writer Euclid around 300 B.C. Analytic geometry follows the pioneering work of the French mathematicians René Descartes (1596-1650) and Pierre Fermat (1601-1665) to impose a coordinate grid on the plane, making it possible to study geometric objects (e.g., lines, parabolas, and circles) by means of algebra (e.g., linear equations and quadratic equations) and vice versa.
 * To the mathematical researcher geometry is a subject that has grown far from its roots, and he may refer to his field as modern geometry to distinguish it from the school subject. Modern geometry comes in two main flavours: algebraic geometry (Algebraic curves and surfaces, algebraic varieties), and differential geometry (Riemannian geometry, Spin geometry, Lie groups and algebras). Differential geometry is used in many ways; to describe the universe in the theory of general relativity (Lorentzian 4-manifolds), to describe soap bubble films (minimal surfaces) and as the building blocks of particle physics (Lie groups).

The first part of this wiki textbook aspires to be a high school geometry text adequate to satisfy the California curriculum content standards.

Why invest the energy to learn geometry?
Basic geometry is a very powerful practical problem solver. It was used by the ancient Egyptians and Greeks for solving most problems and was the proto-type for rational thinking. Where we use algebra today the Greeks used geometry then. It is still very current in all the building and fabrication trades. Before building something big and expensive it is better to work out the bugs in a small scale model. Before expending a lot of energy in making a model it is best to do a drawing. With geometry the drawings become very accurate and can be used to predict measurements and costs. Geometry can be easy to master; the proofs are more fun than sudoko; and its applications are as practical as a hammer and saw. It will give you a sophisticated visual intuition and a strong sense of rational proof and a jumping-off place for some of the most abstract areas of pure mathematics. It’s hard to imagine a mathematical education without geometry.

What should I know before attempting this text?

 * Read Geometry for Elementary School. It will make you comfortable with the terms and diagrams used here.

 * You should be able to do arithmetic up to addition of fractions without a calculator (1/4 + 2/5 = 13/20); and solve simple algebra problems (2x -1= 0 then x= 1/2) and (X^2-16=0). Often algebra and geometry are taught together and the students would know enough algebra by the time they needed it. It wouldn't hurt to read the first few chapters in both arithmetic and beginning algebra while doing geometry. Mathematics builds on itself. This means that only if you work all the examples and learn the definitions will later pages make sense to you. Keep a notebook and make lots of drawings. Talking to others about what you learn is invaluable. You do your part and a good text book will get you there. Unit 1 from Algebra should be more than enough to achieve proficient knowledge for this book.

How difficult? Intuition vs. rigor:
Fifteen little boys sit in front of their first soccer coach, knowing nothing about the game. The coach stands up to teach them soccer. How does he begin?

Perhaps he lectures for several hours, explaining the rules of soccer along with common strategies and tactics. The little boys grow bored. Having no experience of the game, they have trouble understanding the rules and even more trouble remembering them. By the end they have no sense of what a soccer game feels like.

On the other hand, perhaps the coach divides the boys into two teams, takes them to a soccer field, throws them a ball, tells them, "Try to get the ball into the other team's goal and keep it out of your own," and then lets them play. Knowing no rules, the boys play a game little like soccer. They pick the ball up and run with it, paying no attention to the boundaries of the field. When they finally get the idea to kick the ball, they have no skill at dribbling, passing, or working together as a team. They have some fun, but again they end up not knowing what a soccer game feels like.

The first approach (teaching all the rules before playing) is what mathematicians might call a rigorous approach to soccer while the second (just playing without worrying about rules) is what they might call an intuitive approach. Rigor emphasizes the rules. Intuition emphasizes the play. Good teaching and good learning need a balance of both. A good soccer coach starts by teaching the boys some of the most important rules, making them practice some basic drills, and letting them play a little. At first he probably emphasizes the intuitive, letting them play more, so that they get a sense of how the game works and how much fun it can be. Later, as they develop a taste for the game, he focuses more on skills and drills, on rules, strategy, and tactics.

The teacher of beginning geometry students faces the same question as the soccer coach: emphasize rigor or emphasize intuition? Following the example of the good coach, this first chapter emphasizes intuition while introducing a little rigor. Specifically this chapter introduces many of the elementary concepts and much of the terminology of geometry in the context of an intuitive treatment of Euclidean geometry. Later chapters revisit these topics with greater rigor.

So, for instance, this chapter addresses Euclidean geometry without explaining what makes it Euclidean and without mentioning other sorts of geometry. Again, since elementary geometers think of points as dots, this chapter explains that a point is like an infinitely small dot. It is a helpful mental image that has served geometers well for over 2000 years. Rigorous approaches to geometry leave the term point undefined, but this text reserves that subtle and confusing convention for a later chapter. Again, this text assumes that its readers already understand something about area and volume and the units for measuring them, so it does not try to define and explain standard units of area and volume.

title: Geometry/Introduction


text:
User talk:鼠

そうですか.

Hi Nezumi-san! Welcome to the Japanese wikibook project and thanks for joining us. I apologize for all those discussions you saw. I don't think it was very constructive. No point to argue all day desho?

Don't worry about your pages being deleted. You're very much welcome to do whatever you like. It's nice to see people contributing new ideas. I really look forward to your Kanji lessons section :D — [[User:Mkn|Mkn (Talk)]] 00:32, 10 Nov 2004 (UTC)

Japanese wikibook
Hey,

For some reason the Japanese wikibook mailing list disappeared. If you're still interested in working on the Japanese wikibook please sign up for the new Japanese wikibook mailing list. Thanks. - Sik0fewl 02:20, 5 May 2005 (UTC)

title: User talk:鼠


text:
Wikijunior talk:Solar System/Venus

Sources used:

 * Venus (planet) -- General data
 * -- Weight data
 * Atlas of the universe ISBN 0-540-06087-9 -venus facts
 * Venus Revealed: A new look below the clouds of our mysterious twin planet (1997); Grinspoon, David Harry; ISBN 0-201-40655-1; Helix Books: Addison-Wesley Publishing Company, Inc.

In both the Mercury and Venus articles, the lack of a moon is explained in the same way. I think it would make sense for Mercury to have the explanation, and Venus to refer to Mercury's explanation. The section about Venus' moon would still have content, due to the story of its fabled moon.

Mihoshi 02:19, 11 Apr 2005 (UTC)

"Venus'" or "Venus's" as possessive
This goes back to my Senior year of high school (and English 101) where I wouldn't have swore that when you make a possessive out of a word that ends in the letter "s", you simply put the apostrophe on the end. Apparently I'm in an edit war over this with Laurascudder, so now I'm appealing to the community in general to decide this issue. This is like the name of the magazine Boys' Life (note the apostrophe on the end.) I guess to clarify things we could also simply use the term Venusian (as opposed to Venerial which is the correct term but usually not used in scientific circles to talk about things pertaining to Venus and only used in medical journals instead). --Rob Horning 02:43, 29 July 2005 (UTC)

 * Technically the apostrophe only rule is only applicable when the s on the end is due to a plural. An example is that you write Texas's rather than Texas' because Texas is singular but boys' instead of boys's because boys is plural (See for instance University of Minnesota style guide).  This is however a frequently confused rule.  --Laura Scudder | Talk 18:55, 29 July 2005 (UTC)

I've seen (and myself use) constructions such as Texas' meaning "of Texas" along the lines of "two days' time" meaning "the time of two days". Would we write (or try to say) "two days's time"..? I'm not convinced the rule given in the University of Minnesota's style guide is generally considered to be a rule – but then I suppose there's no final arbiter to whom to appeal. So I'll just say that "Texas's" (and "Venus's", etc) looks odd to me! Best wishes, David Kernow 15:12, 8 December 2005 (UTC)

 * K, if that's what you guys want, I'm not going to fight it. Let me just point out that there's ~400k instances of Texas's on the internet according to google.  — Laura Scudder | Talk 16:02, 8 December 2005 (UTC)

I don't know what the conclusion to this was, but I'm editing it as "Venus's" because this is what it is correct grammatically, rather than taking artistic license to make it anything else. In any case, the possessive form is definitely not "Venuses", which I had to edit it from. MiltonT 19:53, 6 October 2006 (UTC)

title: Wikijunior talk:Solar System/Venus


text:
Celestia/Bookmarks

Introduction
A Cel: URL is a bookmark that saves the time, location, rendering options and other settings of a specific Celestia event or place. These URLs can be exported and published as regular HTML, so that any Celestia user can share a Celestia scene with any other.

The Windows version of Celestia includes a Bookmark menu. Those bookmarks are not the same as Cel: URLs.

To record a Cel: URL to your computer's "clipboard", type a Ctrl-C, or the usual "copy selected region" keyboard shortcut. On a Windows system, you can type a Ctrl-Insert.

To paste a Cel: URL into a document, type a Ctrl-V, or the usual "paste clipboard".

Potential incompatibility warning
Unfortunately URLs recorded by one version of Celestia often are not compatible with other versions. The origin of Celestia's coordinate system changed in V1.5. As a result, URLs recorded by previous versions of Celestia place the viewpoint hundreds of AU from the intended viewpoint. Similarly, the rotation of the Earth was greatly improved in Celestia v1.6. As a result, URLs recorded by V1.5 for viewpoints on the Earth's surface will place the viewpoint tens of kilometers from the intended viewpoint. Also, although URLs recorded by previous versions of Celestia can be read by V1.6, the URLs generated by V1.6 cannot be used by previous versions of Celestia.

Fix for Linux if clicking on a Cel: URL does not work
Depending on the specifics of your installation, Celestia might not have been registered to handle the Cel: URLs. If that is the case, you can remedy as follows (this should work on any system compliant with the XDG specifications).

 * 1) Enter   in a terminal. (This registers Celestia as the program that handles cel: links.)
 * 2) Edit , replacing the line   with  , so that the system knows that it has to pass the URL argument to Celestia, when launching it. The desktop file is usually found in   and if you don't want to edit files with root, you can instead copy it to   and edit it there (or more generally copy it from   to  ). Optionally, you can also add   to the desktop file. (See the XDG desktop entry spec.)

title: Celestia/Bookmarks


text:
Perl Programming/Numbers

Numbers
Numbers in Perl do not have to be enclosed in any kind of punctuation; they can be written as straight numbers.

Floating-point numbers
Here are some acceptable floating point numbers:

0.1, -3.14, 2.71828…

Integers
Integers are all whole numbers and their negatives (and 0): {… -3, -2, -1, 0, 1, 2, 3, …}.

Here are a few examples of integers:

12, -50, 20, 185, -6654, 6654

The following examples are not integers:

15.5, -3.458, 3/2, 0.5

Non-decimal numbers
I'll dwell on this topic for a little longer than the other types of numbers. In Perl you can specify not only decimal numbers, but also numbers in hex, octal, and binary. If you are not familiar with how these systems work, you can try these Wikipedia articles:

 * Hexadecimal
 * Octal
 * Binary

In Perl you have to specify when you are going to write a non-decimal number. Binary numbers start with an 0b, so here are some possible binary numbers:

0b101011101

0b10

Octal numbers start with 0 ("zero"), so here are some possible octal numbers:

015462

062657

012

Hexadecimal numbers start with 0x, so here are some possible hexadecimal numbers:

0xF17A

0xFFFF

Number Operators
Just like strings, numbers have operators. These operators are quite obvious so I'll just give a quick example of each one.

The +, -, /, and * operators
These operators are pretty obvious, but here are some examples:

100 + 1 # That's 101 100 - 1 # That's 99 100/2 # That's 50 100*2 # That's 200

Perl also has the familiar increment, decrement, plus-equals, and minus-equals operators from C: $a++   # evaluate, then increment ++$a   # increment, then evaluate $a--   # evaluate, then decrement --$a   # decrement, then evaluate $a += 5 # plus-equals operator, adds 5 to $a. Equivalent to $a = $a + 5 $a -= 2 # minus-equals operator, subtracts 2 from $a. Equivalent to $a = $a-2

Now let's look at one more operator that's a little less obvious.

The ** Operator
The ** operator is simply the exponentiation operator. Here's another example:

2**4 # That's 16, same as 24 4**3**2 # that's 4**(3**2), or 49, or 262144

Exercises

 * Remember the x operator? Use a mathematical expression as the number of times to repeat the string, see what happens.
 * Write a program like our original hello world program except make it print a mathematical expression.

Perl/Números

title: Perl Programming/Numbers


text:
User:Toriber

Heriberto Cantu Villarreal P15 Biologia

title: User:Toriber


text:
Wikijunior talk:Solar System/Mercury

Sources

 * Mercury (planet) -- General data
 * Mercury (mythology)
 * NASA -- Nasa overview
 * NASA kid's site -- Some trivia
 * nineplanets.org -- More general data
 * mathforum.org -- Weight data

Size of Mercury
I simplified the section on Mercury's size, thinking that our target audience wouldn't need three decimal places when comparing it to the Earth and moon. I changed it to "a little over a third as big as the Earth," and changed the moon comparison similarly. I also deleted the fifth significant figure for the size in km, figuring such percision unnecessary.

My version is not necessarily the best way to phrase it either, though, so feel free to edit as you will. --Asbestos 00:06, 15 Nov 2004 (UTC)

Mythology
Though none of the other planet articles have expanded this section yet, I figured saying why a planet was named after a certain god was important. I've started changing it in this direction, feel free to expand. On a completely unrelated note, I felt a little like Calvin from Calvin and Hobbes: "Mercury was a Roman God with winged feet... Why they named a planet after this guy, I can't imagine. Um... back to you, Susie..." --Asbestos 00:45, 15 Nov 2004 (UTC)

I've also added a possible "Mythology box." Do people think such asides are good? -- Asbestos 20:52, 15 Nov 2004 (UTC)

I love the Mythology Box! Such asides usually make it more interesting, especially in children's books. Lady~Macbeth 02:18, 10 Jun 2005 (UTC)

Orbital precession
Is the concept of orbital precession too advanced for a book of this nature? As you probably know, in physics the precession of the orbit of Mercury is considered important as it helped confirm Einstein's theory of relativity. Historically people tried to explain the discrepancies in the rate of precession by predicting the existence of the planet Vulcan. (Which may be an interesting section all by itself.) — 130.76.32.15 14:55, 27 Jun 2005 (UTC)
 * Try to simplify (in this case really simplify) the issues and bring up the larger issues of being very close to a massive object like the Sun. Another place you could write up this issue in terms of relativistic effects could be in a supplimental article like the existing How was the Solar System born? article.  These are planned to be a part of the appendix when the book is formally put together.  Rob Horning 9 July 2005 11:00 (UTC)

How long is a year on this planet?
Wouldn't this sentence: "This means that an eight-year-old person would be 32 years old on Mercury."

suggests the reader that they will biologically age faster in Mercury? How about: "... would be 32 Mercury years"?

 * Sounds great -- go for it. --SV Resolution 17:37, 8 September 2005 (UTC)

Mercury Facts

 * Mercury's surface temperature can vary from -300 °F (-180 °C) to 800 °F (430 °C). The hottest shade temperature ever felt on Earth was only 58 °C (136 °F)!

- mixed use in the same line of: xxx °F (yyy °C) - versus - xxx °C (yyy °F) - dominant use on other Solar System pages seems(?) to be, xxx °C (yyy °F) ? making the (yyy °X) part slightly differ might make it a little more readable. (whole book!) (--MvGulik 23:53, 20 October 2005 (UTC))

 * That isn't "mixed use". It is consistent use of the logical and proper convention for expressing converted values:  List the original first, followed by the converted value in parentheses.  You can see from the roundness of the numbers that the degrees Fahrenheit are the likely originals.  But we know that the 58 °C was originally made on the Celsius scale, in part because those are the only units of temperature for weather used where it was made.  Metric1000 13:39, 21 October 2005 (UTC)

 * It is consistent use if you are aware of the rule that is applied. Not sure how I should have know this. --MvGulik 09:49, 22 October 2005 (UTC)

 * I was just trying to point out that there are several different bases from which you can look at consistency, and they aren't always compatible with each other. You could certainly find publications which do follow an "English units first" or "metric units first" rule and things like that.  I'm just arguing that the better position is "originals first", because, as pointed out below, that is often the best indicator of the precision of the original measurement, and also because, if an error has been made in conversion--which happens quite often, it is a clue as to which one is more likely correct.  Metric1000 14:23, 22 October 2005 (UTC)

 * Note, however, for the stuff below as well, that the better and easier to read conversion style groups ranges of numbers:
 * Mercury's surface temperature can vary from -300 °F to 800 °F (-180 °C to 430 °C). The hottest shade temperature ever felt on Earth was only 58 °C (136 °F).
 * Metric1000 13:55, 21 October 2005 (UTC)

Line Example: normal
 * Mercury's surface temperature can vary from -180 °C (-300 °F) to 430 °C (800 °F). The hottest shade temperature ever felt on Earth was only 58 °C (136 °F)!

Line Example: italic
 * Mercury's surface temperature can vary from -180 °C (-300 °F) to 430 °C (800 °F). The hottest shade temperature ever felt on Earth was only 58 °C (136 °F)!

Line Example: small
 * Mercury's surface temperature can vary from -180 °C (-300 °F) to 430 °C (800 °F) . The hottest shade temperature ever felt on Earth was only 58 °C (136 °F) !

Full Example's:

Mercury Facts:
 * Mercury orbits the Sun faster than any other planet.
 * Mercury's surface temperature can vary from -180 °C (-300 °F) to 430 °C (800 °F) . The hottest shade temperature ever felt on Earth was only 58 °C (136 °F) !
 * Radar observations suggest that there is frozen water on Mercury's north pole.

Mercury Facts:
 * Mercury orbits the Sun faster than any other planet.
 * Mercury's surface temperature can vary from -180 °C (-300 °F) to 430 °C (800 °F). The hottest shade temperature ever felt on Earth was only 58 °C (136 °F)!
 * Radar observations suggest that there is frozen water on Mercury's north pole.

Mercury Facts:
 * Mercury orbits the Sun faster than any other planet.
 * Mercury's surface temperature can vary from -300 °F (-180 °C) to 800 °F (430 °C). The hottest shade temperature ever felt on Earth was only 58 °C (136 °F)!
 * Radar observations suggest that there is frozen water on Mercury's north pole.

--MvGulik 23:53, 20 October 2005 (UTC)

PS: considering the text in the side box is larger than normal text, the small text variant might become to small. --MvGulik 00:17, 21 October 2005 (UTC)

 * The second example is bad, because the rules say that symbols for units of measure can never be italicized.
 * Smaller numbers for he converted values is a bad idea.
 * As I said above, originals first! Metric1000 13:55, 21 October 2005 (UTC)

 * Italic: Aha, did not know that. --MvGulik 09:49, 22 October 2005 (UTC)

Incorporating all of my suggestions, plus the &minus; symbol: Metric1000 14:08, 21 October 2005 (UTC)

Mercury Facts:
 * Mercury orbits the Sun faster than any other planet.
 * Mercury's surface temperature can vary from −300 °F to 800 °F (−180 °C to 430 °C). The hottest shade temperature ever felt on Earth was only 58 °C (136 °F)!
 * Radar observations suggest that there is frozen water on Mercury's north pole.

 * While there aren't "rules" about use of symbols, there are "style" guidelines that suggest you may be correct. A good "style" suggestion as well is consistancy.  If you are going to be quoting temperatures like this, be consistant with your units like this box:

Mercury Facts:
 * Mercury orbits the Sun faster than any other planet.
 * Mercury's surface temperature can vary from −300 °F to 800 °F (−180 °C to 430 °C). The hottest shade temperature ever felt on Earth was only 136 °F (58 °C)!
 * Radar observations suggest that there is frozen water on Mercury's north pole.

Still, I like this one better, and is clean and to the point. Parenthesis tend to break up thoughts and reading, so grouping the concept of the range is a good one. I also agree that as a matter of style italics are inappropriate here. As a general style guideline as well, don't put in false precision when doing conversions between Imperial (American now?) units and Metric units. I hate it when you see something like 100 miles (160.94 km) when you were talking about a rough distance to somewhere. Instead it should be somewhat close in precision like 100 miles (160 km) where you can assume in this case +/- 10 km accuracy. Things like diameters of asteroids and moons generally only have about 2 digit accuracy anyway, and in some cases even the order of magnitude is a guess. --Rob Horning 17:27, 21 October 2005 (UTC)

 * I repeat, the consistency to strive for is originals first; not some artificial notion that some particular unit of measure should come first.
 * The reason for this has a lot to do with your point about precision. That temperature was originally measured as 58 °C, likely on a thermometer that only had the Celsius scale.  Assuming that this was accurately measured to the nearest degree Celsius, it would be somewhere between 135.5 °F and 137.3 °F; to the nearest degree Fahrenheit, it might have been 136 °F or 137 °F.
 * However, if it is instead stated as 136 °F first, this creates the misleading impression that it was measured to the nearest degree Fahrenheit, and would be somewhere in the 57.5 °C to 58.1 °C range if accurately measured to greater precision.
 * Similarly, with the originals first in the other numbers, there are two logical choices for the precision of the conversion: either −300 °F to 800 °F (−200 °C to 400 °C) or −300 °F to 800 °F (−180 °C to 430 °C) would work, but if we can safely assume that the originals have been kept in the primary position, we have a better idea how precise those numbers actually are, no matter which conversion is used.  Metric1000 20:41, 21 October 2005 (UTC)

Bye bye & GL. (I would clean up, but u 2 are still talking) --MvGulik 09:49, 22 October 2005 (UTC)

 * We are not talking about a formal scientific journal, where the original numbers are of huge importance and it is critical that the original data is preserved (like real scientists never fudge the data anyway). This is a book for kids, for crying out loud.  The consistancy is to deal with the cultural context of what units the kids may be familiar with, although even in the USA it is likly that the kids reading this are familiar with the metric system.  If this were to be published in the EU as a primary target, it would be better if the temperature and distances listed would be in metric measurements first.  The dual listing of imperial and metric units is done in part to help encourage a transition away from the imperial units, but use them when that is all the reader may be familiar with.  --Rob Horning 14:39, 22 October 2005 (UTC)

 * In this particular case, the figures currently in the Wikipedia article are expressed in kelvins: 90 K minimum, 400 K mean, 700 K maximum, 103 K average night, 623 K average day (in at least the last two cases, there is a fairly good chance they are from originals in degrees Celsius, to the nearest 10 degrees).
 * Using those values as the originals, it is fine with me if it is expressed as (-180 °C to 430 °C (-300 °F to 800 °F). It is merely coincidence that rounding the degrees Fahrenheit to the nearest ten degrees gives us numbers divisible by 100.  Metric1000 15:37, 23 October 2005 (UTC)

Needs reorganizing and more
Despite the fact that all the tasks seem to have been checked off, this page looks like it needs some help. Can the proofreading page be essentially reset to start the proofreading process over again? I don't want to upset anyone by undoing their hard work, but looking at the dates and arguments, someone needs to be bold if any of these books are going to reach the finished stage.

Starchildmom 20:16, 3 April 2006 (UTC)

"Fun facts" boxes
I quite liked the two boxes that used to be in this article (which can be seen in this version). They were removed by User:Shanel with no explaination. I'm not sure if the problem was the formatting (they took up a bit of room when there was very little on the page), but I think that these articles ought to include such things, especially as having the exact same structure in every article in the series can be fairly boring. — Asbestos | talk (not signed in), 21:02, 18 April 2006 (UTC)

Image
The classical depiction of Mercury was removed by User:Starchildmom. I think that either it or a similar image should go back. Are we trying to make this article as dry as possible? — Asbestos | talk (not signed in), 21:08, 18 April 2006 (UTC)

 * The images have been removed due to some discussion that they detract rather than enhance from the content here. While classical art is interesting, and the names of many bodies of the Solar System are based on ancient mythology, this is not an art history book.  Notably the images of Europa and Neptune were borderline pornographic, and either we need to get something a tad bit more conservative or simply leave them out.  This isn't fighting NPOV, but rather that we want to allow this content to the widest possible audience.  I agree that a classical depiction of Mercury would be useful, so if you know of some images that we could use to represent these greek gods that are 1) availble under GFDL-compatable licenses, 2) are otherwise culturally neutral in their appearance and 3) fairly consistent within the set between one diety and another.  That is also the importantce of each point, I would add, but it seemed as though point #2 was failing with some of these images, and none of the images seemed to show any consistancy of any sort on point #3.  If you are an artist, would you want to give it a try?  --Rob Horning 23:06, 18 April 2006 (UTC)

title: Wikijunior talk:Solar System/Mercury


text:
General Biology/Cells/Cell Structure

Cell structure
What is a cell? The word cell comes from the Latin word "cella", meaning "small room", and it was first coined by a microscopist observing the structure of cork. The cell is the basic unit of all living things, and all organisms are composed of one or more cells. Cells are so basic and critical to the study of life, in fact, that they are often referred to as "the building blocks of life". Organisms - bacteria, amoebae and yeasts, for example - may consist of as few as one cell, while a typical human body contains about a trillion cells.

According to Cell Theory, first proposed by Schleiden and Schwann in 1839, all life consists of cells. The theory also states that all cells come from previously living cells, all vital functions (chemical reactions) of organisms are carried out inside of cells, and that cells contain necessary hereditary information to carry out necessary functions and replicate themselves. It is the basis of human life.

All cells contain:
 * Lipid bilayer boundary (plasma membrane)
 * Cytoplasm
 * DNA (hereditary information)
 * Ribosomes for protein synthesis

Eukaryotic cells also contain:
 * At least one nucleus
 * Mitochondria for cell respiration and energy

Cells may also contain:
 * Lysosomes
 * Peroxisomes
 * Vacuoles
 * Cell walls

Concepts

 * Plasma Membrane : Phospholipid bilayer, which contains great amount of proteins, the most important functions are the following:
 * 1) It selectively isolates the content of the cell of the external atmosphere.
 * 2) It regulates the interchange of substances between the cytoplasm and the environment.
 * 3) Communicates with other cells.
 * Model of the fluid mosaic : Describes the structure of the plasma membrane, this model was developed in 1972 by cellular biologists J. Singer and L. Nicholson.
 * Phospholipid bilayer : Is in the plasma membrane and produces the fluid part of membranes.
 * Proteins : Long chains of amino acids.
 * Glucose proteins : Proteins together with carbohydrates in the plasma membrane, mostly in the outer parts of the cell.
 * Functions of proteins : Transport oxygen, they are components of hair and nails, and allow the cell interact with its environment.
 * Transport Proteins : Regulate the movement of soluble water molecules, through the plasma membrane. Some transport proteins called channel proteins form pores or channels in the membrane so that water soluble molecules pass.
 * Carrying proteins : Have union sites that can hold specific molecules.
 * Reception proteins : They activate  cellular responses  when specific molecules join.
 * Proteins of recognition : They work as identifiers and as place of union to the cellular surface.
 * Fluid : It is any substance that can move or change of form.
 * Concentration : Number of molecules in a determined unit of volume.
 * Gradient : Physical difference between two regions of space, in such a way that the molecules tend to move in response to the gradients.
 * Diffusion : Movement of the molecules in a fluid, from the regions of high concentration to those of low concentration.
 * Passive transport : Movement of substances in a membrane that doesn’t need to use energy.
 * Simple diffusion : Diffusion of water, gases or molecules across the membrane.
 * Facilitated diffusion : Diffusion of molecules across the membranes with the participation of proteins.
 * Osmosis : Diffusion of the water across a membrane with differential permeability.
 * Transport that needs energy : Movement of substances across a membrane generally in opposition to a gradient of concentration with the requirement of energy.
 * Active transport : Movement of small molecules using energy (ATP).
 * Endocytosis : Movement of big particles towards the interior of the cell using energy. The cells enclose particles or liquids.
 * Pinocytosis : (Literally cell drinking) Form in which the cell introduces liquids.
 * Phagocytosis : Way of eating of the cells. It feeds in this case of big particles or entire microorganisms.
 * Pseudopodia : False feet (the amoeba).
 * Exocytosis : Movement of materials out of the cell with the use of energy. It throws waste material.
 * Isotonic : The cytoplasm fluid of the interior of the cells is the same that the outer.
 * Hypertonic solution : The solutions that have a higher concentration of dissolved particles than the cellular cytoplasm and that therefore water of the cells goes out with osmosis.
 * Hypotonic : The solutions with a concentration of dissolved particles lower than the cytoplasm of a cell and that therefore do that water enters the cell with osmosis.
 * Swelling : Pressure of the water inside the vacuole.
 * Endoplasmic Reticulum : It is the place of the synthesis of the cellular membrane.

Structure and function of the cell

 * Rudolf Virchow : Zoologist, who proposed the postulates of the cellular theory, observes that the living cells could grow and be in two places at the same time, he proposed that all the cells come from other equal cells and proposed 3 postulates:
 * 1) Every living organism is formed from one or more cells
 * 2) The smallest organisms are unicellular and these in turn are the functional units of the multicellular organisms.
 * 3) All the cells come from preexisting cells.

Common characteristics of all the cells

 * Molecular components : Proteins, amino acids, lipids, sweeten, DNA, RNA.
 * Structural components : Plasmatic membrane, cytoplasm, ribosomes.
 * Robert Hooke : He postuled for the first time the term cell
 * Prokaryotes : Their genetic material is not enclosed in a membrane ex. Bacterias
 * Eukaryotes : Their genetic material is contained inside a nucleus closed by a membrane

History of cell knowledge
The optical microscope was first invented in 17th century. Shortly thereafter scientists began to examine living and dead biological tissues in order to better understand the science of life. Some of the most relevant discovery milestones of the time period include:

 * The invention of the microscope, which allowed scientists for the first time to see biological cells
 * Robert Hooke in 1665 looked at cork under a microscope and described what he called cork "cells"
 * Anton van Leeuwenhoek called the single-celled organisms that he saw under the microscope "animalcules"
 * Matthias Jakob Schleiden, a botanist, in 1838 determined that all  plants  consist of cells
 * Theodor Schwann, a zoologist, in 1839 determined that all  animals  consist of cells
 * Rudolf Virchow proposed the theory that all cells arise from previously existing cells

In 1838, the botanist Matthias Jakob Schleiden and the physiologist Theodor Schwann discovered that both plant cells and animal cells had nuclei. Based on their observations, the two scientists conceived of the hypothesis that all living things were composed of cells. In 1839, Schwann published 'Microscopic Investigations on the Accordance in the Structure and Growth of Plants and Animals', which contained the first statement of their joint cell theory.

Cell Theory
Schleiden and Schwann proposed spontaneous generation as the method for cell origination, but spontaneous generation (also called abiogenesis) was later disproven. Rudolf Virchow famously stated "Omnis cellula e cellula"... "All cells only arise from pre-existing cells." The parts of the theory that did not have to do with the origin of cells, however, held up to scientific scrutiny and are widely agreed upon by the scientific community today.

The generally accepted portions of the modern Cell Theory are as follows: (1) The cell is the fundamental unit of structure and function in living things. (2) All organisms are made up of one or more cells. (3) Cells arise from other cells through cellular division. (4) Cells carry genetic material passed to daughter cells during cellular division. (5) All cells are essentially the same in chemical composition. (6) Energy flow (metabolism and biochemistry) occurs within cells.

Microscopes

 * Allow greater resolution, can see finer detail
 * Eye: resolution of ~ 100 μm
 * Light microscope: resolution of ~ 200 nm
 * Limited to cells are larger organelles within cells
 * Confocal microscopy: 2 dimension view
 * Electron microscope: resolution of ~0.2 nm
 * Laser tweezers: move cell contents

Cell size
One may wonder why all cells are so small. If being able to store nutrients is beneficial to the cell, how come there are no animals existing in nature with huge cells? Physical limitations prevent this from occurring. A cell must be able to diffuse gases and nutrients in and out of the cell. A cell's surface area does not increase as quickly as its volume, and as a result a large cell may require more input of a substance or output of a substance than it is reasonably able to perform. Worse, the distance between two points within the cell can be large enough that regions of the cell would have trouble communicating, and it takes a relatively long time for substances to travel across the cell.

That is not to say large cells don't exist. They are, once again, less efficient at exchanging materials within themselves and with their environment, but they are still functional. These cells typically have more than one copy of their genetic information, so they can manufacture proteins locally within different parts of the cell.

Key concepts: Cell size:
 * Is limited by need for regions of cell to communicate
 * Diffuse oxygen and other gases
 * Transport of mRNA and proteins
 * Surface area to volume ratio limited
 * Larger cells typically:
 * Have extra copies of genetic information
 * Have slower communication between parts of cell

Structure of Eukaryotic cells
Eukaryotic cells feature membrane delimited nucleii containing two or more linear chromosomes; numerous membrane-bound cytoplasmic organelles: mitochondria, RER, SER, lysosomes, vacuoles, chloroplasts; ribosomes and a cytoskeleton. Also, plants, fungi, and some protists have a cell wall.

Structure of the nucleus
The nucleus is the round object in the cell that holds the genetic information (DNA) of the cell. It is surrounded by a nuclear envelope and has a nucleolus inside.

Nuclear envelope
The nuclear envelope is a double-layered plasma membrane like the cell membrane, although without membrane proteins. To allow some chemicals to enter the nucleus, the nuclear envelope has structures called Nuclear pores. The nuclear envelope is continuous with the endoplasmic reticulum.

Nucleolus
The nucleolus appears in a microscope as a small dark area within the nucleus. The nucleolus is the area where there is a high amount of DNA transcription taking place.

Chromatin
Chromosomes consist of chromatin. This is made up of strings of DNA, which typically measure centimeters in length if stretched out. This DNA is wound around a histone core and organized into nucleosomes.

The chromatin must be uncoiled for gene expression and replication. Chromosome micrograph

Endoplasmic reticulum
The endoplasmic reticulum is a cellular organelle made up of a series of extended folded intracellular membranes. It is continuous with the nuclear membrane.

There are two main types of endoplasmic reticulum:
 * RER: rough endoplasmic reticulum (site of protein synthesis) associated with ribosomes
 * SER: smooth endoplasmic reticulum (site of lipid synthesis)

Rough Endoplasmic Reticulum
Proteins are directed to the RER by a signal sequence of a growing polypeptides on the ribosome. This is recognised by a signal recognition particle which brings the ribosome/polypeptide complex to a channel on the RER called a translocon. At the translocon, the signal sequence and ribosome/polypeptide complex interact with the translocon to open it. The signal sequence becomes attached to the translocon. The ribosome can continue to translate the polypeptide into the lumen of the RER. As synthesis continues, 2 processes can happen.

 * 1) If the protein is destined to become a membrane bound protein then the protein synthesis will continue until termination. The ribosome can then dissociate, allowing protein folding within the RER lumen to occur and continuation to the golgi apparatus for processing of the polypeptide.
 * 2) If the protein is destined for storage for later secretion after stimulation or for continuous secretion then a protease -an enzyme which cuts proteins at the peptide bond- can cut the signal sequence from the growing polypeptide. Continuation to the golgi etc. can then occur.

When produced, proteins are then exported to one of several locations. The proteins are either modified for extracellular membrane insertion or secretion. Note, this is in contrast with ribosomes which do not associate with the RER and produce proteins which will become cytosolic enzymes for example.

Smooth Endoplasmic Reticulum
Smooth endoplasmic reticulum produces enzymes for lipid and carbohydrate biosynthesis and detoxification RER

Sarcoplasmic Reticulum
This is a specialised form of endoplasmic reticulum found in some muscle cell types-particularly striated, skeletal muscle. Its main function is different from the other 2 types in that is mainly acts as a storage of calcium. This reticulum has voltage gated channels which respond to signals from 'motor neurones' to open and release calcium into the cytoplasm. This can then bring about the next part in muscle contraction.

The Golgi apparatus
The golgi apparatus is made up of multiple stacks of bilipid membranes.
 * Proteins made on the RER are modified and then sorted
 * Formation of secretory vesicles
 * Formation of lysosomes (intracellular digestion)

Other membrane-bound cytoplasmic organelles include:
 * Microbodies (generic term)
 * Glyoxysome (transforms fat into carbohydrate in plants)
 * Peroxisome (uses oxidative metabolism to form hydrogen peroxide and is destroyed by catalase)

Ribosomes
Ribosomes are the site of protein synthesis. Ribosomes themselves are synthesized in the cell nucleoli and are structured as two subunits, the large and the small. These parts are composed of RNA and protein.

Prokaryotic and eukaryotic ribosomes are different, the eukaryotic ones being larger and more complicated.

DNA-containing organelles
Mitochondria Chloroplast Centrioles
 * Double membrane
 * Aerobic metabolism, internal membrane
 * DNA, ribosomes
 * Give rise to new mitochondria
 * Double membrane
 * Photosynthesis, internal membrane
 * DNA, ribosomes
 * Give rise to new chloroplasts
 * Microtubule organizing centers
 * Animal cells and many protists
 * Pair constitutes the centrosome
 * Give rise to flagellum during spermatogenesis
 * Consist of 9 triplet microtubules
 * Mitosis, meiosis

Cytoskeleton
Cytoskeleton is a collective term for different filaments of proteins that can give physical shape within the cell and are responsible for the 'roads' which organelles can be carried along.

 * Gives the cell shape
 * Anchors other organelles
 * Vital to intracellular transport of large molecules

The cytoskeleton is composed of 3 main types of filaments:
 * Actin filaments (7 nm)
 * Microtubules: (25 nm) polymer of tubulin; 13/ring.
 * Intermediate Filaments

Both actin and microtubules can have associated motor proteins.

Intermediate Filaments
These are rope like filaments, 8-10 nm in diameter and tend to give the structural stability to cells. Examples include Vimentin, neurofilaments and keratin. It is keratin which principly makes up hair, nails and horns.

Growth
These filaments are 2-stranded and composed of dimeric subunits called G-Actin. They contain a GTP molecule in order to bind (polymerise). As GTP is hydrolysed then the structure becomes unstable and depolymerisation occurs. The growth of actin filaments is concentration dependant-that is, the higher the concentration of free G-actin, the greater the polymerisation. The are also polar, having a + and a - end (not related to charge) and polymerisation tends to happen faster at the + end.

Cilia and flagella are threads of microtubules that extend from the exterior of cells and used to move single celled organisms as well as move substances away from the surface of the cell. motor proteins-move, wave motion

title: General Biology/Cells/Cell Structure