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RNA interference/Medical

This page provides a non-technical exploration of the medical implications of the Nobel Prize in Physiology or Medicine for 2006, which was awarded to Andrew Fire and Craig Mello for their research on RNA interference.

Medical uses of RNA interference
RNA interference might allow future treatments of human diseases such as Lou Gehrig's disease (amyotrophic lateral sclerosis, ALS).

Trapped
Most people experience "sleep paralysis" at some point during their life. While sleeping, you might be aware of trying to move, but being unable to move. The frustrating and sometimes frightening experience of sleep paralysis can provide insight into the experience of living with advanced Lou Gehrig's disease. Most people with Lou Gehrig's disease retain their normal ability to think and reason while just the part of their nervous system that makes movement possible is selectively destroyed. What can go wrong to selective destroy the brain cells that control movement and leave people trapped in a body that will not respond to their wish to move?

The medical strategy
In order to understand functional defects observed in Lou Gehrig's disease, the loss of movement control has been traced to specific organs, cell types and individual genes. What are the structural components of the nervous system that are specifically involved in control of movement? Up until the middle of the 19th century, diseased brain and spinal cord tissue could generally only be productively analyzed in terms of alterations in the gross anatomy. Although microscopy was then allowing advances in cellular pathology -the association of disease processes with structural changes in specific cell types of organs- the individual neurons of the brain and spinal cord were generally resistant to meaningful visualization by microscopy. Anatomists such as Paul Broca were able to associate behavioral defects with structural damage to particular parts of the brain. The part of the brain called "Broca's area" was linked to disruption of speech generation without any block in the ability of patients to comprehend language. Broca's area is connected to nearby parts of the brain that contain cells with axons that carry movement control signals to the spinal cord. The bundles of movement control axons degenerate and are smaller than normal in patients with Lou Gehrig's disease. About a decade after Broca's area was recognized as a movement control area of the brain, Vladimir Betz used a new technique, the Golgi stain, to identify a type of giant pyramidal shaped cells that are movement control cells of the brain. These "Betz cells" are among the largest neurons of the human brain and they are depleted from the brains of patients with Lou Gehrig's disease.

Lou Gehrig's disease is inherited in a genetically dominant way within some families. This pattern of inheritance allowed identification of a specific gene that is linked to the death of Betz cells in some families, the gene for an enzyme called superoxide dismutase. Superoxide dismutase can protect cells from molecular damage caused by oxygen. Normally oxygen is thought of as being required for human life, but the human body must also constantly protect itself from deleterious effects of highly chemically reactive oxygen molecules. Mutant forms of superoxide dismutase can lead to cell death.

Treating Lou Gehrig's disease
Existing treatment options for Lou Gehrig's disease are very limited. Riluzole is a drug that inhibits the ability of some brain cells to generate the electrical signals that are sent down their axons. Clinical studies of patients with Lou Gehrig's disease have shown that some patients may live a few months longer if they are treated with Riluzole. Riluzole may have a beneficial effect by reducing damage to brain cells that naturally arises from their activity. Better treatments are needed that specifically target the causes of Lou Gehrig's disease.

The Nobel Prize-winning research on RNA inhibition might lead to new treatments for patients with Lou Gehrig's disease due to dominant mutations in the superoxide dismutase gene. Reduction in the level of the superoxide dismutase enzyme coded for by the mutant gene has been studied in animal models of Lou Gehrig's disease. Superoxide dismutase is a major protein in the brain and spinal cord, so it is a challenge to find ways to significantly reduce production of this protein in the movement control neurons. "RNA inhibition", often abbreviated "RNAi", is a normal process inside cells by which ribonucleic acid can lead to reduced levels of a specific protein. The specificity arises due to base-pair complementarity between the inhibitory RNA and target nucleic acids that are involved in producing a specific protein.

Since non-mutated superoxide dismutase might be beneficial, it would be useful to have a method that selectively decreases levels of the mutated form. Many dominant disease genes that cause Lou Gehrig's disease are point mutations. The RNA molecules that activate the RNA-mediated inhibition process are about 20 nucleotides in legth. It has been shown that highly selective RNA-mediated inhibition can be induced that selects between normal and point mutant superoxide dismutase.

Working with laboratory mice as an experimental model system for the human disease ALS, Miller et al showed that loss of muscle function could be slowed using RNA interference. This result was obtained by using a virus to induce RNA interference in neurons. Recent results indicate that disease-causing superoxide dismutase that is present in non-neuronal cells also contributes to the death of movement control cells and progression of the disease. These results from laboratory experiments suggest that if RNA-induced inhibition of mutant superoxide dismutase can be induced in the correct cells of the brain and spinal cord, it might be possible to slow progression of Lou Gehrig's disease in humans.

title: RNA interference/Medical


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Writing a simple greeting bot for MediaWiki/Introduction to MediaWiki scripting access

On this page you will get an introductory overview over how MediaWiki works and in which ways it can be accessed from scripts.

Fundamentals
MediaWiki is a PHP web application based on HTTP. Because of that, scripts communicate with MediaWiki in a series of requests and responses. To get the contents of a page, for example, the script sends a request to the server hosting MediaWiki (e.g. http://en.wikiversity.org/). The server then responds with the page content plus some additional statistical information. Each script action, such as loading or saving a page, requires a new set of requests and responses.

Exercise 1 - A simple C# request
Note: the following code example uses C# and the .NET Framework. The use of an Integrated development environment (IDE) is strongly recommended. For Windows users, Microsoft provides a free C# IDE called Visual C# Express. For Linux and Mac users, there is a free IDE called MonoDevelop available.

In this exercise, we will send a request to retrieve the contents of Wikiversity's main page in a file:

Let's take a closer look at what this code does. We
 * 1) We create an   object to hold the address of the page, in this case Main Page.
 * 2) We create a new HTTP request object by calling WebRequest's Create page with the address of the page we want. If you are not familiar with HTTP at all, I suggest taking a quick peek at HTTP.
 * 3) We then set the user agent and content type headers typical for HTTP requests. Although innocent looking, these are actually quite important: MediaWiki refuses any request which does not provide these two headers.
 * 4) By calling , the request is sent and a response retrieved.
 * 5) We read the content of the response and save it to a local file called "Main page.txt".

If you open the file, you will see the same content that would be shown if you went to Main Page with your browser and look at the source of that page (the menu option is commonly called View source oder Page source in graphic browsers).

Where to go next
Writing a simple greeting bot for MediaWiki/Signing in

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


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Java Programming/Boolean variables

Java is one of the languages that explicitly supports a primitive Boolean variable type.

Boolean variables
A primitive variable can be declared to be of type boolean and can have assigned to it one of the two boolean literals true or false.

boolean a = true; System.out.println("a is " + a);

The above code would print a is true.

Relational operators
Java supports the full set of relational operators, as described in the general introduction to Boolean variables. Relational operators can be used to compare any two type-compatible primitives.

At the moment, we have only covered two categories of primitives, numeric and boolean.

Any two values that are numeric (of any type) are, or will be made, compatible. The full suite of relational operators may be used without restriction.

As true and false are not numeric values, neither can be said to be greater or less than the other, in the strict mathematical sense. Only the is equal (==) and is not equal (!=) operators may be used for boolean values. The code below will print c = false.

boolean a = true; boolean b = false; boolean c = a == b;       System.out.println("c = " + c);

Note: the use of a double equal sign for is equal and a single equal sign for assignment is a common source of programming errors. It is very easy to accidentally type just one equal sign character in situations where you want two.

Conditional operators
Conditional operators operate only on boolean values. Java has three, conditional-and, conditional-or, and conditional-not (there is another kind of and, or and not that will be covered later, thus the distinction).

The operator for conditional-and is a pair of adjacent ampersand characters &&. The result of conditional-and is false unless both operands are true. The conditional-and operator has one unusual property that can be both useful and confusing: because the result will always be false if the value of either operand is false, the left operand will always be evaluated but the right hand operator will only be evaluated if the left hand operator evaluates to the value true.

The operator for conditional-or is a pair of pipe characters ||. The result of conditional-or is true unless both operands evaluate to false. If the value of the left-hand operand evaluates to the value true then the right-hand operand is not evaluated.

The operator for conditional-not is a single exclamation point !. This is a unary operation and the result is the opposite of the value of the operand.

Boolean expressions
Not everything is quite as simple as is x greater than two.

Take, for example, leap years. How would you write a Boolean expression that evaluates to true if the value of an integer variable year is that of a leap year in the Gregorian calendar? (n.b. there are several "right" ways to do it)

One way to start it is the obvious way: is year divisible by 4? You would use Java's integer remainder operator (%) and compare the result to 0: (year % 4) == 0. The parentheses are not strictly necessary, but improve readability.

Next, we could check to see that year is not divisible by 100: (year % 100) != 0. Finally, check for year is divisible by 400: (year % 400) == 0. Now combine them all together. The first two checks must both be true for it to be a leap year but if the third check is true then the result will always be true. This fact suggests that perhaps we could put the third check first (to take advantage of short circuiting).

((year % 400) == 0) or ((year % 4) == 0 and (year % 100) != 0)

Now we just need to substitute the Java operators for "or" and "and":

((year % 400) == 0) || ((year % 4) == 0 && (year % 100) != 0)

Exercise Try the expression out in a program. Declare a variable year and assign it a value, then have the program print out a message telling whether or not the value is a leap year.

If statements
The most common use of boolean values will appear in if statements. These statements allow you to designate units of code that will only execute if the boolean condition is true. For example, you can print a message if a given year is a leap year, and remain silent otherwise:

If statements and other flow control constructs will be discussed in more detail in the flow control module.

title: Java Programming/Boolean variables


text:
Lunar Boom Town/Fueling Station

Business idea
Mine or separate out lunar resources required to create a viable rocket fuel for use around Earth-Moon system and deep space. Oxygen is readily available. Buy it from Lox manufacturerLunar_Boom_Town/LOX_Domestic_and_Exports. Aluminum is readily available on the moon although extracting it in large quantities will be challenging and capital intensive.[[Lunar_Boom_Town/Aluminum_Production]|Using Al as a rocket fuel is theoretically possible but also challenging.]

Mix the two into a fuel for shipping to customer site or into a solid form of rocket booster suitable for getting off the lunar surface or both.

Market

 * Any mass, such as lox, which needs to be delivered to space from lunar surface.
 * Short suborbital lunar hopping. Much faster than Rovers or Freight Trucks.
 * Mars resupply missions. Need large delta V to Holman to Mars or Aldrin Cyclers.

External data

 * http://www.space-rockets.com/lsp.html Explanation of a aluminum based rocket fuel
 * Interplanetary travel

title: Lunar Boom Town/Fueling Station


text: Portal:Green chemistry

title: Portal:Green chemistry


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User:ChemGardener

Useful Wikiversity Starting Points

 * Special:Allpages
 * All articles
 * Category:Chemistry
 * Special:All articles
 * Special:Specialpages
 * Category:Community discussions
 * Category:Wikiversity

title: User:ChemGardener


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Microelectromechanical systems

MEMS or Micro Electro Mechanical Systems are sensors and actuators based on certain mechanical principles integrated with electronic circuits (signal transduction unit) for input and output on micro scale.

Learning projects and materials

 * MEMS design

Resources

 * Search for Microelectromechanical systems at Wikiversity
 * Microelectromechanical systems
 * MEMS sensor generations
 * SUGAR (MEMS Simulator)
 * MEMS thermal actuator
 * Accelerometer
 * RF MEMS
 * Vibrating structure gyroscope
 * Microtechnology
 * Lab-on-a-chip

title: Microelectromechanical systems


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User:Wikityke

Just another Wikicontributor

title: User:Wikityke


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Lunar Boom Town/Worm Soil Factory

Business Idea:

Topsoil is going to be at a premium on the moon. As much food as possible must be grown locally and CO2 must be recycled into biomass and oxygen.

Lunar regolith is initially not good topsoil. When moisture is added it creates a base (opposite of acidic) mixture which is inimical to plants. (need footnote here, find source) It also has no organic component.

Hence our worm farms. We purchase waste biomass, combine it with lunar regolith in proper proportions, feed it to our worms, then sell the resulting topsoil to plant growers and the extra worms to chicken farms.

Best of all, our worm farms take a lot less excavated space to operate than other full-blown ranches and farms, thus making it ideal for part-time entrepreneurs who work for other people full-time.

Startup costs:
 * Excavation of initial space for work beds and airlock to adjoining community corridor or owner's living space.
 * Initial supply of worms from Terra.
 * Initial biomass - primarily kitchen scraps, possibly human waste compost.
 * Hauling of initial sifted lunar regolith
 * Water

Design challenges:
 * What is the proper mix of lunar regolith and various types of biomass to create various types of topsoil?
 * What are the various types of topsoil Lunar Boomtown Businesses and residents will purchase?

Mill:
 * Without the weathering provided by the earth's atmosphere and water, individual grains of the regolith have extremely sharp edges, making it highly abrasive. This may be harmful to worms.  In order to blunt the regolith perhaps it could be tossed in a rotating drum.  Non-abrasive regolith may be a saleable product in an and of itself for coating outdoor work areas to reduce wear on equipment.

Oportunity:
 * Perhaps carbon-dioxide, dissolved in water would be a cheap acid for neutralizing the pH. Scoops operating in a low, elliptical orbit around Venus may provide an abundant source of spacebound CO2.

External Information Links

 * http://www.sustainability.vic.gov.au/www/html/1656-how-to-build-a-worm-farm.asp
 * http://www.prospect.sa.gov.au/site/page.cfm?u=959
 * http://www.kidsgardening.com/themes/business8.asp
 * http://www.wnyinsurance-quote.com/information-site/html/here_is_what_you_need_to_get_s.html
 * A Guide for Educators
 * Specialized market as lab specimens? http://www.wormclassroom.org/resources.html

title: Lunar Boom Town/Worm Soil Factory


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Lunar Boom Town/Horticulture Nursery

Business Idea
Raise and sell plants of various kinds. Vegetable starters, flowers, household potted plants, fruit trees, etc. Output determined by customer demand.

Materials Needed

 * Seeds -- Import initial stock from Earth, sell excess in kits and as seeds
 * Containers -- Use sintered regolith.
 * Topsoil -- Purchase from Worm farms or create own?
 * Grow lights
 * Electricity
 * Fertilizer -- Purchase from Worm farms or create own?
 * Water -- Import Hydrogen and mix own or buy from water/air plant
 * CO2 -- Import carbon or purchase CO2 from atmosphere regulators?
 * Oxygen -- Sell excess.
 * Nitrogen -- Import from Earth, experiment to find optimum economic mix in nursery

Customers

 * farms - starters
 * businesses (Potted Plants)
 * hotels
 * spaceports

 * residents (potted plants, garden starters)

title: Lunar Boom Town/Horticulture Nursery


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Talk:CisLunarFreighter

This is referred to a mud. Does this imply the game is to be text based? --Remi 21:27, 23 February 2007 (UTC)
 * No, the game is intended to have graphics involved in the gameplay. It is possible that early prototypes of some game modules could be developed in text only.   Mirwin 20:41, 27 February 2007 (UTC)

Cis?
What does CIS stand for?
 * Based on Cislunar space, I'd say "the volume between geostationary orbit and the moon's orbit". --JWSchmidt 04:37, 13 March 2007 (UTC)

Blender Game Engine
This project can be built entirely using Blender3D features such as the Blender Game Engine, 3D modelling/rendering using Blender's internal rendering system, Blender physics/particle system, animation/sequence editor, and scripting engine using the Python language. I propose we begin considering the stages of this production as an interactive animation project.--Brylie Oxley (discuss • contribs) 21:50, 4 February 2013 (UTC)

title: Talk:CisLunarFreighter


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User talk:Wikityke

add comments below, at the end of the list, please. Thanks 201.53.5.241 22:02, 23 February 2007 (UTC)

the versity suffix
"the versity suffix throws us into a whole new, and very much more exigent and critical arena" <-- Adopting the name "wikiversity" was one of the most contentious issues faced when this project was being planned. Wikiversity is not an attempt to replicate a conventional university as it exists at bricks-and-mortar institutions today. Wikiversity aims to provide learning resources for people of all ages. When I think about the ultimate goal of Wikiversity, I think about the historical origins of universities, collaborative efforts to facilitate learning that brought together learners and teachers. In a sense, we are starting over from that fundamental starting point but doing it in a new medium, a virtual world that is not constrained by the need to work in a restrictive physical space. We are able to explore what can be done in this new virtual space.

"the people who'll come here won't be seeking general knowledge but rather, expecting something much more advanced" <-- In some cases. Wikipedia takes a one-size-fits-all approach to topics. I've noticed that some people go to the discussion pages of the more technical Wikipedia articles and leave comments such as, "Can anyone explain this in English?" Wikiversity can complement Wikipedia by providing introductions to technical topics. But in some cases people will come to Wikiversity because they want to go beyond what is possible at Wikipedia.

"contributors MUST adopt a very much more conscientious, rigorously self-critical and professional attitude than in other wiki-projects (be they formally "qualified" or not) when preparing their submissions, edits, suggestions etc. etc." <-- As a wiki, Wikiversity is open to contributions of all types. I expect that many people will come to Wikiversity and have to learn what it means to function as a scholarly contributor. They will learn by making inept contributions at first and then slowly figuring out how do better. It will be important to have other participants who already have expertise and experience. I am interested in the idea that Wikiversity can establish a system by which the community calls upon its experts to take leadership roles in "more conscientious, rigorously self-critical and professional attitude than in other wiki-projects". See Review board.

"denouncing any error or misconduct" <-- Wikiversity is an experiment in how to apply new technologies to support learning. I hope we can plan ahead so as to avoid many problems. When problems arise, I hope we can learn from them and become stronger. Wikiversity aims to offer for free what many people sell. Sadly, we will receive some harsh comments from people who do not wish us well in our altruistic endeavor.--JWSchmidt 00:26, 24 February 2007 (UTC)

INITIAL logo and motto
If the misssion statement is still open to discussion, it's far too early to defibitively decide on the motto and logo, surely !

It's more than correct to elect an INITIAL motto and logo, but pleaseItalic text, shouldn't be made clear that this should not be "written in stone" and should be open to change as the project evolves/matures. wikityke 22:59, 23 February 2007 (UTC)

 * Thanks for your comment about the Motto_contest. I moved the comment to the project's talk page. To reply: The mission statement seems to have reached a plateau, having not changed much for last few months (i think). Ideally, there would be reciprocal development of the motto/slogan/logo and mission statement. I think that, indeed, we can now revisit the mission and polish that in light of the motto/slogan/logo. It should be noted that everything about Wikiversity is in a beta stage and I'm not sure but the main principles developed now might be subject to the approval of the Wikimedia foundation. Perhaps the outcomes of the motto & logo contests will lead to more discussion of the mission and vision for the university. Or, perhaps not. Various basic policies are currently being developed. If the project changes direction significantly for whatever reason, then yes, I think it would make sense to revisit the motto & slogan. At this time, I guess I think that if Wikiversity maintains and develops on the foundation of its current structure and goals, then probably no change in motto/slogan is needed, barring future basic problems with such. So, time will tell -- it is early in the life of Wikiversity -- i don't know if we know if things will be maintained or change. --Reswik 00:57, 25 February 2007 (UTC)

title: User talk:Wikityke


text: User talk:Prodego

title: User talk:Prodego


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Example for the Storyboard Artwork Project

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Example for the Storyboard Artwork Project

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Talk:C++/Conditional Statements

awesome :)

Examples
Could you please add some examples for the switch case? I'm not really sure on how to use it.

--Timmeh 1250 23:51, 21 January 2009 (UTC)

Switch statements are often used in place of massive if/else blocks, both to shorten them, and to make them more readable. For example, say you're writing code for a game, in which the player has four possible states - dead, crouching, standing, and jumping - that correspond to four integers respectively (I.E. 0=dead, 1=crouching, etc.) A piece of code telling the game what to do when the player does x action, may need to do something different, depending on the players current state. This could be done with if statements, like so:

if (state==0) { //Dead code here } if (state==1) { //Crouching code here } if (state==2) { //Standing code here } if (state==3) { //Jumping code here }

However, it would be easier and more efficient to use a switch statement, like so:

switch (state) { case 0: //Dead code here break; case 1: //Crouching code here break; case 2: //Standing code here break; case 3: //Jumping code here break;

Sorry for any C++ Syntax or terminology errors, I've been using computer logic for some time now, but I'm still learning C++.

Real world Examples?
I feel like it'd be nice to have a pseudo-real world example in here, just to relate to the reader. For example, Have the user input how much money they have in their wallet. If they have over $200 in it, have the console say "That's a lot of money!" Otherwise, it would say "That's neat." .....don't judge me. My right brain has been feeling weak lately. =) 64.118.9.189 23:08, 17 January 2010 (UTC).

title: Talk:C++/Conditional Statements


text:
User:Dhir

I Want to know about the LAN Chating programming through object oriented programming.

title: User:Dhir


text:
User talk:Chaplin~enwikiversity

Hi Chaplin, and welcome to Wikiversity! Hopefully the links below might help you find out more about what Wikiversity is. If you've any questions - just ask on my talk page. Cheers! Cormaggio beep 12:43, 24 February 2007 (UTC)

question about your edit
What were you trying to do with this edit? --JWSchmidt 02:21, 21 April 2007 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Chaplin. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Chaplin~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:32, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:04, 19 April 2015 (UTC)

title: User talk:Chaplin~enwikiversity


text:
User talk:Brownln

Image copyright problems

 * Your currently affected images are listed below. For each, please provide a license template and source. Thanks. – Mike.lifeguard | @en.wb 23:26, 13 February 2008 (UTC)

 * 2007-04-17 02:34, Brownln: Mayer mLearning.pdf: untagged! ; 0 (0)
 * 2007-04-17 02:38, Brownln: Design Document Example 1.pdf: untagged! ; 0 (0)
 * 2007-04-17 02:47, Brownln: Design document Example 2.pdf: untagged! ; 1 (1)
 * 2007-04-17 02:49, Brownln: Team2 P2 Design Final.pdf: untagged! ; 0 (0)
 * 2007-04-18 05:43, Brownln: TakeTheLead 01.jpg: untagged! ; 1 (1)
 * 2007-04-18 22:10, Brownln: Forrest Website.jpg: untagged! ; 1 (1)

title: User talk:Brownln


text:
User:Nerval

Me

title: User:Nerval


text:
User:JWSchmidt/Blog/23 February 2007

Complementing Wikipedia  Wikipedia is so large that it deforms the conditions for existence of all other wiki projects. In most cases, it helps when Wikiversity participants who are creating webpages here at Wikiversity are aware of the related resources that already exist at Wikipedia. I was pleased to see a new Wikiversity participant plainly express this as the need for "Searching Wikipedia to avoid reinventing the wheel".

I have been thinking about the fact that Wikipedia takes a one-size-fits-all approach to topics. The exception to this is built into the idea that Wikipedia articles can start "simple" and then get more technical towards the bottom. However, I've noticed that some people go to the discussion pages of the more technical Wikipedia articles and leave comments such as, "Can anyone explain this in English?" Wikiversity can complement Wikipedia by providing introductions to technical topics. At the opposite extreme, some people will come to Wikiversity because they want to go beyond what is possible at Wikipedia and investigate topics in greater detail.

None of what I have written above is meant to ignore Wikibooks. Wikiversity participants should search Wikibooks and become aware of existing textbook modules that are related to Wikiversity webpages. However, there is much less content at Wikibooks than at Wikipedia. Based on my experience, in most cases Wikiversity participants will be actively helping to develop Wikibooks textbooks that can be used as resources by Wikiversity participants.

I started using the Science journalism content development project as place to explicitly test ways to take a Wikipedia article as a starting point and then design Wikiversity pages around that existing Wikipedia page. In particular, I selected the Nobel Prize in Physiology or Medicine learning project as my starting point. My goal with that project is to make sure that Wikiversity has learning resources related to each year's Nobel Prize. So far there is only the RNA interference page for the 2006 prize. That page now explicitly directs Wikiversity participants to individually decide if the related Wikipedia article is too technical or if it does not go into enough detail. For people who need a less technically detailed learning resource, there is a link to a subpage, RNA interference/Medical, where a less technical description of the medical implications of the Nobel Prize-winning research is outlined (still under construction at this moment). Anyone who wants to go into additional details is invited to join in further exploration of the topic, ask questions, and join in discussions.

This website has another approach, providing a set of questions about a topic, each with links to basic and advances options.

title: User:JWSchmidt/Blog/23 February 2007


text:
Python Concepts/Flow control

Boolean Expressions
Python has a Boolean type. The two values for this type are True and False. Note the capitalization: the first letter must be capitalized. Most text editors, including IDLE, will highlight True and False when properly capitalized.

The bool Function
If you need to convert something into a Boolean value, use the  function. For example:

In Python, the integer 0 evaluates to. All other integers will evaluate to.

Strings behave similarly: an empty string evaluates to, all other strings evaluate to.

Note that what is in the string does not matter: It can be "0", "False" or "ReallyReallyFalse": Everything that is not simply an empty string will evaluate to True.

This means we can write such useful constructs as  which will execute a block of code only if the string is non-empty.

Comparison Operators
Python has a number of built-in comparison operators. They are very versatile and can often be used across data types.

Equality
The Python operator for Equality is ==. Let's try it out:

Conjunction
The Python operator for conjunction is.

The  operator works by evaluating until it runs into something False, and return the value that evaluated to False. If everything is True, it returns the last thing it evaluated.

This means that in a Boolean context the result is evaluated to True or False in the way we would expect, using the actual value means that we can benefit from useful side effects in other contexts.

Disjunction
The  operator works similar to the   operator. It returns the first value to be True, or the final value if there is no True value.

Inversion
The  operator returns the opposite of the value passed to it.

Interestingly, Python treats the set of strings as having a True value, even if the strings themselves are empty. Since the set the set contains two strings, it really isn't empty, even if the strings are.

Comparison
The  operator compares two values to see if they match. Note that floating point and integer values are not the same thing.

chains like the  operator, evaluating to False if any part is False.

Contains
The  operator checks a list of things or a string to see if a value is present. Note that floating point and integers evaluate to the same thing for. If an array is present then it checks against the whole value of the components of the array, not against the contents of the components in the array.

needs an array of values to check against, checking in the same way as  produces an error.

Flow Control
Now that you know all these great ways to work with Booleans, let's use them!

if, elif, and else
Python the keyword  to determine   it should execute a section of code. You can tell which lines are in this section by the level of indentation. The general format of if goes like this: if [Boolean Expression]: some code rest of code

This allows for very simple logic. What if you want to have two options, similar to  in other languages? Instead of Case, python uses. if [Boolean Expression]: code elif [Boolean Expression]: More code else: Even more code rest of program

If the Boolean expression for the first  is True, nothing in the   section will execute, nor will anything in the else section. If there are multiple things that could evaluate to True, use multiple if statements.

That code sample also introduced the  statement. gets executed if the  statement's Boolean expression, and the Boolean expressions for all the   statements (if there are any), evaluate to False.

So, how about some actual code? Here's a simple program; try entering this into IDLE and running it. Don't forget to define the function.

While
While is our first example of a loop. While evaluates a Boolean expression, and if that expression is True, it runs some section of code. It then re-evaluates that Boolean expression: if it still evaluates to True, then it runs again. It keeps running - possibly forever! - until that loop evaluates to False, at which point the program continues with whatever comes after the while loop.

Let's take our previous example. That program ran once, and even if nothing was entered, it was done. Let's suppose we instead want a program that "won't take no for an answer": We'll use a while loop to make the prompt show up again and again until we get some response:

That's even better. However, there are a couple of things I don't like about it. First, I don't like that first Boolean expression. After all, we know that:

Therefore, wouldn't it make more sense just to test if name is False than to test if it's True that it's equal to ""?

And do we really want to test if it's True than to Test that it's True that it's equal to False?

That's right! Python has a "not" keyword, which acts a lot like ! in other languages.

We're missing one last thing: whatever comes after the "while" is automatically evaluated as a boolean expression. That means that in many cases (this one included) we can leave out the. (There will still be cases where it's needed, though, so remember that it exists!) while not name: # This is exactly the same as 'while name == "":', but a lot clearer. Okay, good? Cool. It's time to add a new feature: The for loop.

For concept in lesson: learn(concept)
If you thought the Python idioms for the while loop were cool, the for loop is even better. A for loop takes this basic form syntax-wise: for [variable name] in [sequence]: code The for loop will execute enough times that each element of "sequence" is assigned to "variable" once. For example: Of course, any data type could be within the sequence. While we're at it, let's use a descriptive variable name: As you can see, then, for loops make it easy to iterate over a sequence, or in simpler terms, to do something with each entry in a list. For loops are also excellent for times when you need to run a while loop a fixed number of times. Let's compare doint that with a for loop and a while loop: While this is legal Python code, it's not really descriptive. Furthermore, when working with large code blocks, it's easy to forget to add 1 to the variable (in this case 'c') at the end. Fortunately, we can do the same thing with a for loop, in a clearer fashion. Note how we don't have to worry about declaring i, or automatically incrementing it. It's also significantly faster, although most of the time your code will run fast enough anyway.

Note that while we used 'i' as the variable name, you could use anything else. As a general rule, when using the variable as a counter, simply use 'i'; this convention is widely followed and helps other programmers know exactly why you chose a for loop. Otherwise, use a descriptive variable name. For example:

The main reason we use while loops is sometimes we need to repeatedly prompt a user to get a valid input. Simply put, use while when you don't know or can't calculate how many times a loop will run. If you can, use for.

title: Python Concepts/Flow control


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Template talk:Doi

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gives

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User:Fuzzypickles

User:fuzzypickles/Calculus1

title: User:Fuzzypickles


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School:Sports and hobbies

Welcome to the School of Sports and Hobbies, part of Practical Arts and Sciences

Sports

 * Climbing
 * Football (American)
 * Futsal
 * Golf
 * Gymnastics
 * Rodeo
 * Running
 * Volleyball
 * Yoga
 * Basketball

Hobbies

 * Hobbies
 * Speedcubing

News

 * 24/02/07 - School founded
 * 27/02/15 - First sports history resource on collegiate volleyball: 1998 UAAP Women's Volleyball

Learning projects

 * Sport

Lectures

 * Sports

Active participants

 * Since 25 May 2015 with contributions to Sports --Marshallsumter (discuss • contribs) 05:15, 17 April 2018 (UTC)

Things you can do!

 * Clean up Draft:Journalism and move it to become a subpage of a supporting main page learning project.
 * Clean up Draft:Literature and move it to become a subpage of a supporting main page learning project.
 * Clean up Draft:Medicine and move it to become a subpage of a supporting main page learning project.
 * Clean up Draft:Orthomolecular medicine and move it to become a subpage of a supporting main page learning project.
 * Clean up Draft:Sex integration and move it to become a subpage of a supporting main page learning project.
 * Clean up Draft:Sports and move it to become a subpage of a supporting main page learning project.

title: School:Sports and hobbies


text: User talk:Jim mac

title: User talk:Jim mac


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Introductory Classical Mechanics/Introduction

Classical Mechanics is the study of large (relatively speaking) objects, as opposed to quantum mechanics, which studies particles and very small objects, or relativity, which pertains to very large objects (on the order of stars and galaxies) and objects moving very quickly, over about .5c. The field includes Newton's laws of motion and gravitation and Kepler's laws of planetary motion, in addition to other laws and the application of these laws to real world problems. Classical Newtonian mechanics is accepted as incorrect due to errors observed on large scales, such as the progression of the perihelion of Mercury, which motivated Einstein to create General relativity, or under certain other circumstances including blackbody radiation, which motivated Max Planck to author his papers generating the quantum hypothesis. The theory is accurate on large scales to an incredible degree of accuracy.

Units of Measurement
Physics today uses an internationally agreed system of units for measurement. These units are precisely defined and are known as SI Units, (SI is an abbreviation of the system's French name Système international d’unités). The system defines 7 base units, and several derived units. The derived units can all be defined in terms of the base units. The base units are as follows:

In order to simplify the writing of very small or very large quantities of units, prefixes denoting an order of magnitude are used. These are also defined by by the Système Internationale and are thus called SI prefixes, or sometimes metric prefixes. They also help to simplify equations. The following table lists the officially defined prefixes.

Newton's laws
Newton's legacy is founded upon the three concepts he contributed to the idealogical world. They are his three laws of motion, his law of gravitation, and calculus. They work hand in hand in defining Newtonian mechanics. Since his time, physics as a subject has always been taught in that order, simply because each concept builds upon the work of the one before.

Before jumping into the subject at hand, it is worth it to note that Newton did not create the three laws of motion from scratch. Physics, and mechanics along with it, came before Newton. He observed nature carefully, working upon the hypotheses and knowledge of his predecessors, such as Galileo and Kepler. His modification and research lead to the formation of his three laws of motion. Hence his famous saying: "If I have seen further it is by standing on the shoulders of Giants."

His formal approach starts with a few axioms. His model of the world was of masses and forces. They form a powerful theoretical framework where the real world can be simulated. However powerful it may seem, do treat them as merely a theoretical construct and not the real thing, for they must be discarded once they do not function.

Firstly, we must define force. A force is a push or a pull, very close to how they are normally defined. However, it would be rather difficult to visualise a force that acts at a distance or that acts on a mass uniformly.

The First Law
The first law states that A body at rest stays at rest and a body in uniform motion stays in uniform motion unless acted upon by an outside force.

This law is formulated as the fundamental principle in Newton's work, and it is also known as the law of inertia. It references Aristotle's work, which states the complete opposite. This law is important for its intellectual leap, not for the mathematical use, simply because this law is completely embedded in the second law. Where mathematics becomes a hindrance, as in Newton's time, it will be helpful.

The Second Law
Newton's second law of motion states that The rate of change of momentum of a body is proportional to the resultant force acting on the body and is in the same direction. In mathematical terms, that is $$\Sigma \vec{F} = \frac{d\vec{p}}{dt}$$ where $$\vec{F}$$ refer to the various forces acting on the body and $$\vec{p}$$ refers to the momentum of the body.

This forces us to define momentum. Momentum is a mathematical product of mass and velocity. Specifically, it is mass times velocity. Then, what are mass and velocity? Velocity is the speed AND direction of the body's motion. Mass, however, is something that is totally new. It is a quantity attached to all objects; a number that Newton's theory must enforce in order to work. Luckily, from the information given so far, it is possible to define it backwards. Since we know of the law of inertia, we can define mass, inertia mass, as how difficult it is to change the motion of a body. In fact, it is possible to define the unit mass as the amount of matter (same thing as mass) in a body which changes by a unit velocity when subjected to a unit force for a unit time. $$\Sigma \vec{F} = \frac{d\vec{p}}{dt} = \frac{d}{dt}(m\vec{v})$$ $$\therefore m \frac{\Delta v}{\Delta t} = \Sigma \vec{F}$$ for constant mass and force over time. $$m = \frac{\Delta t}{\Delta v} \Sigma \vec{F}$$

The Third Law
Newton originally formulated the third law as To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. However, because of the fact that English evolves over time, we have to replace actions with forces in our modern context. It is therefore shortened to For every force there is an equal, but opposite, force

Please do note that the opposing force has to act on the other body, and is in most cases ignored.

The Law of Universal Gravitation
Two bodies exert a force on each other directly proportional to the product of their masses and inversely proportional to the square of the distance between them. That is $$F_g=G\frac{m_1m_2}{r^2}$$, where $$G$$ is a constant of proportionality.


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Template:Citation/doc

The Citation template is a versatile template for citing books, periodicals, contributions in collective works, patents, and web-sites. Its goal is to be an all-purpose citation template. It also has functionality to aid the use of the Harvard referencing style. The template allows author-date ("Harvard") citations in the main body of text to link to a full citation (generated by this template) in a "References" section at the end of the article via the Template:Harvard citation template. This template creates an HTML anchor to which the Harvard citation and related templates can link.

The template knows whether you are citing a book, periodical, or a chapter in a compilation, depending on which combination of parameters you use. For use with author-date systems such as the Harvard citation template, use of last and date parameters should be considered mandatory, where possible.

TemplateData
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Theory of relativity/General relativity

General relativity (GR), also known as the General Theory of Relativity, is an extension of special relativity, dealing with curved coordinate systems, accelerating frames of reference, curvilinear motion, and curvature of spacetime itself. It could be said that general relativity is to special relativity as vector calculus is to vector algebra. General relativity is best known for its formulation of gravity as a fictitious force arising from the curvature of spacetime. In fact, "general relativity" and "Einstein's formulation of gravity" are nearly synonymous in many people's minds.

The general theory of relativity was first published by Albert Einstein in 1916.

General relativity, like quantum mechanics, (relativity and quantum mechanics are the two theories comprising "modern physics") has a reputation for being notoriously complicated and difficult to understand. In fact, in the early decades of the 20th century, general relativity had a sort of cult status in this regard. General relativity and quantum mechanics are both advanced college-level and postgraduate level topics. We won't attempt to give a comprehensive explanation of general relativity at the expert level. But we will attempt to give a rough outline, for reasonably advanced students, of the general relativistic formulation of gravity, below. A somewhat simpler, but, we hope, still reasonably literate, introduction for students may be found here.

Modern science does not say that Newtonian (classical) gravity is wrong. It is obviously very very nearly correct. In the weak field approximation, such as one finds in our solar system, the differences between general relativity and Newtonian gravity are minuscule. It takes very sensitive tests to show the difference. The history of those tests is a fascinating subject, and will be covered near the end of this article. But in all tests conducted so far, where there are discrepancies between the predictions of general relativity and Newtonian gravity (or other competing theories for that matter), experimental results have shown general relativity to be a better description.

Outside of the solar system, one can find stronger gravitational fields, and other phenomena, such as quasars and neutron stars, that permit even more definitive tests. General relativity appears to pass those tests as well.

This is not to say, by any means, that general relativity is the ultimate, perfect theory. It has never been unified with modern formulations of quantum mechanics, and it is therefore known to be incorrect at extremely small scales. Just as Newtonian gravity is very nearly correct, and completely correct for its time, general relativity is believed to be very nearly correct, but not completely so. Contemporary speculation on the next step involves extremely esoteric notions such as string theory, gravitons, and "quantum loop gravity".

The theory was inspired by a thought experiment developed by Einstein involving two elevators. The first elevator is stationary on the Earth, while the other is being pulled through space at a constant acceleration of g. Einstein realized that any physical experiment carried out in the elevators would give the same result. This realization is known as the equivalence principle and it states that accelerating frames of reference and gravitational fields are indistinguishable. General relativity is the theory of gravity that incorporates special relativity and the equivalence principle.

Click here for a simple introduction for students.

Click here for video lectures by Kip Thorne of Caltech on the mathematics of General Relativity.

Curved space-time
To fully describe the location of an event in our universe, something that occurs at a particular time and place, requires three dimensions of space and one time. In flat spacetime the Cartesian coordinates are often represented in index notation, x=x1, y=x2, z=x3 and Einstein referred to time as a fourth dimension ct=x4, though it is more common today to list the time first as ct=x0. In the early development of relativity it seemed simple to consider time as an imaginary number ict where i is the quadratic root of -1 and c the speed of light. Then the space-time has the following four dimensions: (x,y,z,w=ict), but in modern pedagogy this has been abandoned as it is now understood that the metric tensor is what carries the sign difference in inner product operation yielding a spacetime displacement (line element) between events in flat spacetime of ds2 = dct2 - (dx2 + dy2 + dz2) Calculation of the Riemann tensor for this line element yields all zero elements and so when line elements are frame transformations of this one they also yield a zero Riemann tensor and are said to correspond to flat spacetime. When there is a matter source, the Riemann tensor is not zero and then the line element that yields that Riemann tensor can not be globally transformed into that of the flat spacetime line element of special relativity above, so it is said that spacetime.

Riemann coordinates
Understanding of general relativity, like restricted relativity, will be easier by first looking at the calculus of curved spacelike coordinates called Riemannian tensor calculus and first at the case of a surface described by two dimensions (x,y) instead of four. Generalizing the Riemann tensor and the calculus of curved space to four dimensional spacetime is referred to as pseudo-Riemannian tensor calculus. Cartesian coordinates are the most common reference system. The Earth, being spherical,  is not a flat space and the Pythagorean theorem is valid only locally. The cartesian frame changes its orientation from place to place but the law of gravity is the same in Paris or in Valparaiso. The Riemann coordinates are local cartesian coordinates. They are such that the Pythagorean theorem is valid even on a curved surface. It is not necessary to know the transformation from curved coordinates to use them. They are not always suitable; for example, it is necessary to compute the Riemann tensor in Gauss (e.g. spherical) coordinates in order to obtain the Schwarzschild metric.

The metric
The metric of a euclidean space represents, the Pythagorean theorem. With the $$\left(-+++\right)$$ sign convention reduced to the Euclidean three dimensions of space the theorem is $$\left. ds ^2 = dx^2 + dy^2 + dz^2 \right. $$

The line element for a two dimensional surface of coordinates x and y which is curved is according to Gauss: $$\left. ds ^2= g_{xx} dx^2 + 2 g_{xy} dx dy + g_{yy} dy^2\right.$$

where the gij are the coefficients of the metric. Every curved surface may be approximated, locally, by the osculating paraboloid, becoming the tangent plane  z=0 when the principal curvatures kx and ky cancel: $$z= \frac{1}{2}\left(k_{x} x^2 + k_{y} y^2\right) $$

Indeed, in the frame used, the axes Ox and Oy are in the tangent plane z=0, the origin of the coordinates, x=0, y=0 being at the contact point. The Gauss curvature is, by definition, the product of the principal curvatures: $$ K=k_{x}k_{y}=  \frac{\partial ^2 z}{\partial x^2} \frac{\partial ^2 z}{\partial y^2} $$

In order to be in Riemann coordinates, it remains to orient the axes Ox and Oy in such a manner that the metric be diagonal. The computation is given in: $$ds^2= dx^2 + \left[1 - K\left( x^2 + y^2\right)\right] dy^2$$

where K= kxky is the Gaussian curvature. In this expression, we have gxx=1, gxy=0 and $$g_{yy} =1 - K\left( x^2 + y^2\right) $$ It is not necessary to determine the principal directions to work with the Riemann coordinates since the laws of physics are invariant under a frame change. It is also not necessary to change the scales of the coordinate axes to get a metric with coefficients equal to one. It only assumed that it is always possible to change the coordinates in such a way that the Pythagorean theorem is verified locally, at the contact point, taken as the origin of the coordinates. In Riemann coordinates, all the paraboloids, including the sphere, locally, have the same metric, provided that they have the same Gaussian curvature.

The line element applied to a real particle of any sort describes the world line or path of the particle through spacetime and its length integrated along the path is the proper time for the particle. As such it is proper to use the +--- sign convention for the metric of spacetime so that ds along the path of a real particle is itself real representing the proper time differential dct. With the +--- sign convention the rectilinear coordinate line element of special relativity becomes $$ds^2 = dct^2 - dx^2 - dy^2 - dz^2 $$ Just as the introduction of the metric tensor $$g_{ij}$$ allowed Gauss to describe paths along curved surfaces, the introduction of it in general relativity allows for the description of curved spacetimes $$ds^2 = g_{\mu \nu}dx^{\mu}dx^{\nu}$$ where we here use the Einstein summation convention where a high and low repeated index is summed over from 0 to 3. This set of elements $$g_{\mu \nu}$$ is known as the covariant "metric tensor".

Riemann tensor
Gauss found a formula of the curvature K of a surface with a computation, complicated in Gaussian coordinates but much simpler in Riemannian coordinates where the curvature and the Riemann tensor are equal (in two dimensions) : $$ R_{xyxy}= -\frac{1}{2}\left(\frac{\partial ^2 g_{xx}}{\partial y^2} + \frac{\partial ^2 g_{yy}}{\partial x^2}\right) $$

Let us check that the Riemann tensor is equal to the total Gauss curvature: $$R_{xyxy}= -\frac{1}{2}\left(\frac{\partial ^2 g_{xx}}{\partial y^2} + \frac{\partial ^2 g_{yy}}{\partial x^2}\right)= 0 -\frac{1}{2}(-2K)=K $$ We have also, by partial derivation of the coefficients of the metric: $$\frac{\partial ^2 g_{xx}}{\partial x^2} + \frac{\partial ^2 g_{xx}}{\partial y^2}= 0 $$

The same for gyy $$\frac{\partial ^2 g_{yy}}{\partial x^2} + \frac{\partial ^2 g_{yy}}{\partial y^2}= -4K $$ We have obtained a Laplace equation and a Poisson equation.

In full four dimensional spacetime the entire expression for the Riemann tensor in terms of the Christoffel symbols is $$R^{\lambda}_{\mu \rho \nu}=\Gamma ^{\lambda}_{\mu \nu},_{\rho}-\Gamma ^{\lambda}_{\mu \rho},_{\nu}+\Gamma ^{\lambda}_{\sigma \rho}\Gamma ^{\sigma}_{\mu \nu}-\Gamma ^{\lambda}_{\sigma \nu}\Gamma ^{\sigma}_{\mu \rho}$$

Einstein equations in vacuum
Einstein's hypothesis is that the curvature of space-time is zero in the vacuum which is thus a flat space. This is true in two dimensions where the Gaussian curvature is zero. In higher dimensions, only the Ricci tensor is zero according to the Einstein equation. In matter, the Ricci tensor is different from zero. We shall not consider this case, here, but it should be considered to describe the universe which contains matter. The Einstein equations are, in the vacuum: $$\left.R_{ik}= 0\right.$$

Rik is a complicated function of the various componants of the Riemann tensorRijkl and of the metric gik. The Ricci tensor, like the Riemann tensor depends only on the coefficients of the metric. The Christoffel symbols are then unnecessary intermediaries. In two dimensions, the Ricci tensor has two components each proportional to the single component of the Riemann tensor. Therefore there is only one Einstein equation in two dimensions: $$\left.R_{xyxy}= 0\right.$$

In two dimensions and in Riemann coordinates, the Riemann tensor is equal to the Gaussian curvature K, which is zero in the vacuum. Then the coefficients of the metric have to satisfy the Laplace equation Δgxx=0 and Δgyy=0. But, in two dimensions, the Laplace equation diverges unless the coefficients of the metric are constants, corresponding to a pseudo-euclidean space.

In full four dimensional spacetime General relativity/Einstein equations $$G^{\mu \nu}-\lambda g^{\mu \nu}=kT^{\mu \nu}$$ in vacuum and for a zero cosmological constant are $$G^{\mu \nu}=0$$ $$R^{\mu \nu} - \frac{1}{2}g^{\mu \nu}R=0$$ Contracting this with the metric tensor yeilds $$R - \frac{1}{2}g^{\mu \nu}g_{\mu \nu}R=0$$ $$R - \frac{1}{2}4R=0$$ Yeilding a zero Ricci-scalar $$R$$: $$R=0$$ Inserting above then, Einstein's field equations in vacuum and a zero cosmological constant reduce to a statement that the Ricci tensor $$R^{\mu \nu}$$ is zero: $$R^{\mu \nu}=0$$

Gravitational waves
Replacing y by ict in the Laplace equation, one obtains the d'Alembert equation of the plane gravitational waves for two of the coefficients of the metric: $$\frac{\partial ^2 g_{xx}}{\partial x^2} - \frac{1}{c^2}\frac{\partial ^2 g_{xx}}{\partial t^2} = 0 $$ $$\frac{\partial ^2 g_{tt}}{\partial x^2} - \frac{1}{c^2}\frac{\partial ^2 g_{tt}}{\partial t^2} = 0 $$ The Brinkmann solution which is the exact solution to Einstein's field equations for gravitational and electromagnetic plane polorized waves traveling in the + x direction is $$ds^2 = dct^2 - \left(dx^2 + dy^2 + dz^{2}\right) + h\left(x-ct,y,z\right)\left(dx - dct\right)^2 $$

and though Khan, Penrose and Szekeres have written an exact solution for colliding plane waves, exact solutions to the field equations for astronomical sources for which the waves would not be plane waves are not known. As such the theoretical modeling of gravitational wave emissions are based on weak field approximations of Einstein's field equations. Measurements on the orbital decay of binary pulsars agree with such weak field approximation predictions on the amount of energy carried away by gravitational waves, but otherwise gravitational waves have not yet been directly detected.

Einstein and Newton
The two-dimensional Laplace equation may be extrapolated in higher spaces with small curvature. In three dimensions, spherical symmetry and time independent metric, the Einstein equations reduce to the radial laplacian: $$ \frac{1}{r^2}\frac{d}{dr}\left(r^2\frac{dg_{rr}}{dr}\right)= 0 $$ and for $$ g_{tt}$$. Its solution is the Coulomb potential in 1/r: $$ds^2= g_{tt} dct^2 + g_{rr} dr^2= \left(A'+ \frac{B'}{r}\right) dct^2 - \left(A+ \frac{B}{r}\right) dr^2$$

The correspondence principle with special relativity will give us the integration constants A and A'. For r=∞, we have: $$ds^2= A' dct^2 - A dr^2$$

It should be the Minkowski metric: $$ds^2=dct^2 - dr^2$$ Identifying these two metrics, we get A=A'=1. Yeilding $$g_{tt} = \left(1+ \frac{B'}{r}\right)$$ The geodesic equation is $$\frac{d^{2}x^{\lambda}}{d\tau ^{2}} + \Gamma ^{\lambda} _{\mu \nu} \frac{dx^{\mu}}{d\tau} \frac{dx^{\nu}}{d\tau}=0$$ At low speeds the only contributing terms are $$\frac{d^{2}x^{\lambda}}{d\tau ^{2}} + c^2 \Gamma ^{\lambda} _{00} \left(\frac{dt}{d\tau}\right)^2 =0$$ And in the Newtonian limit $$dt=d\tau $$ so the equation of motion reduces to $$\frac{d^{2}x^{\lambda}}{d\tau ^{2}} + c^2 \Gamma ^{\lambda} _{00} =0$$ Writting the Christoffel symbol in terms of the metric $$\frac{d^{2}x^{\lambda}}{d\tau ^{2}} + \frac{c^2}{2}g^{\lambda \rho}\left(g_{0\rho},_{0} + g_{\rho 0},_{0} - g_{00},_{\rho}\right) =0$$ This metric is time independent $$\frac{d^{2}x^{\lambda}}{d\tau ^{2}} - \frac{c^2}{2}g^{\lambda \rho}\left(g_{00},_{\rho}\right) =0$$ And diagonal so the only contributing $$g^{\lambda \rho}$$ is for $$\rho =\lambda$$. Looking At radial motion for simplicity: $$\frac{d^{2}r}{d\tau ^{2}} - \frac{c^2}{2}g^{rr}\left(g_{00},_{r}\right) =0$$ In the weak field $$g^{rr} \approx -1$$ $$\frac{d^{2}r}{d\tau ^{2}} + \frac{c^2}{2}\left(g_{00},_{r}\right) =0$$ which in terms of the metric element found above is $$\frac{d^2 r}{d\tau ^2 } + \frac{c^2 }{2} \left(\frac{\partial}{\partial r}\left(1+\frac{B'}{r} \right) \right) = 0$$ for this to correspond to Newtonian dynamics then $$\frac{c^2 }{2}\frac{B'}{r}$$ must therefor be the Newtonian gravitational potential $$\Phi = -\frac{GM}{r}$$ resulting in $$B' = - \frac{2GM}{c^2}$$ where G is the gravitation constant, M the mass of the attracting star.

According to Einstein, the determinant (or its trace for low gravitation) of the metric should be equal to one. This can be shown by solving the four-dimensional Einstein equations for a static and spherically symmetric gravitational field. Therefore we may write B=-B' and obtain an approximation of the Schwarzschid metric: $$ds^2= \left(1- \frac{2GM}{rc^2}\right) dct^2 - \left(1+ \frac{2GM}{rc^2}\right) dr^2 - r^2 d\theta ^2 - r^2 sin ^2 \theta d\phi ^2$$

This metric gives a light deviation by the sun twice as predicted by the newtonian theory or by the first Einstein theory of 1911 where time is dilated by gravitation. In his 1916 theory, gravitation dilates time and contracts space. The exact Schwarzschild metric is $$ds^2= \left(1- \frac{2GM}{rc^2}\right) dct^2 - \frac{dr^2 }{ \left(1- \frac{2GM}{rc^2}\right)} - r^2 d\theta ^2 - r^2 sin ^2 \theta d\phi ^2$$ The Schwarzschild metric is an exact vacuum solution to General relativity/Einstein equations.

Problems of general relativity
There are strong indications the general relativity theory is incomplete. The problem of quantum gravity and the question of the reality of spacetime singularities remain open, see section Quantum gravity. Observational data that is taken as evidence for dark energy and dark matter could indicate the need for new physics, see section Cosmology. See also Lorentz-invariant theory of gravitation.

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Portal:African history

Welcome to the Department of African History Part of the School of History and the School of African Studies.

The Department of African History wishes to provide a comprehensive understanding of the history of the African cultures.

Division description
The scope of this division is the following:

 * To create a comprehensive annotated bibliography of publications and materials on African history.
 * To improve the quality of Wikipedia articles on topics related to African history.
 * To develop free teaching materials for schools outside of Africa. African history is a severely underrepresented topic in school curricula. As a result, misconceptions about Africa, often originating in racist ideologies of the colonial times, are still widespread among Europeans and Americans. To solve this problem, course materials should be developed that can be used by history teachers in Europe, America and other parts of the world.
 * To develop free books or teaching materials about African history for primary school and pre school level so that educators and parents can work against the formation of misconceptions about Africa at an early age.
 * To develop free teaching materials for African schools. The teaching of history in African school curricula is often highly eurocentric and based on European curricula of France and the United Kingdom so that students often learn more about European history than about the history of their own country and continent. The teaching materials for African schools might or might not be identical to the teaching materials for non-African schools or might share modules with them. They might be more detailed in some areas than the teaching materials for non-African schools and might be complemented with regional materials that provide in depth coverage of the regional history of certain parts of Africa and can be used regionally.
 * To develop free textbooks and teaching materials for academic level education about African history.
 * To discuss how such teaching materials can become incorporated into the curricula of Schools inside and outside of Africa.
 * To do original research in African history.

The scope of this department is not limited to written history but may include knowledge on African history gained from other disciplines like archeology, oral history research, linguistics, comparative ethnology, genetics etc.

Research Projects

 * Institute of History of Racism
 * North west African continental shelves
 * Slavery
 * South east African continental shelves

Active participants
If you would like to contribute to this, please add a reference to your user page here.
 * Since 25 June 2012 with Libyan history. --Marshallsumter (discuss • contribs) 02:26, 18 April 2018 (UTC)

Inactive participants

 * User:Nannus: will forward the Legendary brisf history of the Akans and particularly my family. Adako Royal family and our history since the 1100AD.

Department news

 * 25 February 2006 - Department founded!
 * 20 May 2013 - Early telescopes is a Special Story for This month in GLAM
 * 7 October 2016 - Slavery announced on Main Page News!
 * 21 January 2017 - Paleanthropology announced on Main Page News!
 * 22 July 2017 - Comparison between Roman and Han Empires announced on Main Page News!
 * 29 August 2017 - Sustainable Development Goals announced on Main Page News!
 * 29 August 2017 - Pre-Late Egyptian Reconstruction announced on Main Page News!

title: Portal:African history


text:
Portal talk:African history

I just noticed that I was not logged on when I founded this school. So that was me. If you have questions or remarks, you can contact me on my talk page. Nannus 13:06, 25 February 2007 (UTC)

Tasks
Would love to see a tasks page for this Department. The Jade Knight 04:17, 14 March 2008 (UTC)

title: Portal talk:African history


text:
Racism/History

Races in the sense of this project are social, cultural or political constructions in the form of explicit or implicit racist ideologies, created for purposes like exploitation and suppression. Races in the sense of this institute are groups of people discriminated against (positively or negatively) by a racist ideology. The aim of the research is to find out how, when, where, by whom and for what reason and purpose such constructions have been created, how the ideas involved developed and how they influenced history. In this sense, the research of this institute may be called biased.

Scope
The scope of this project may include questions like:

 * Research about the origin of racism
 * in Western culture.
 * Where and when did the idea of dividing humans into "races" originate. Possible questions here are for example:
 * Is the origin of racism related to the Spanish reconquista, the crusades etc.?
 * Where, when and why did the specific anti-"black" form of racism in Western culture begin?
 * Does it stem from Arab-Muslim prejudices against non-Arabs during the Umayyad conquests?
 * Are its roots to be found in Biblical Israel, or earlier?
 * in Chinese Culture
 * What are the oldest Chinese records which state that non-Chinese peoples are racially inferior?

Initially, an annotated bibliography about this topic shall be developed. This can then be used to develop teaching materials and to improve the quality of the coverage of the subject on Wikipedia. (An example of the method to be used for this can be seen in the Department of African philosophy.)

Further goals of this project include:
 * Creating the basis for the improvement of the quality of coverage of these topics in Wikipedia.
 * Creation of teaching materials about the origins and history of racism for schools and universities worldwide.

Links
Racism

title: Racism/History


text: User talk:Jimbobjames

title: User talk:Jimbobjames


text:
Talk:Racism/History

I am not myself a historian. If you are, please consider contributing here. Nannus 13:52, 25 February 2007 (UTC)
 * Just a note: This doesn't really belong in the Department of European History, particularly as it is a global topic.  A course on "The History of Racism in Europe" should be cross-listed here and in European History, however.  If you don't have any objections, I'll make the relevant changes.  The Jade Knight 18:53, 25 February 2007 (UTC)
 * Hi. I agree that this really belongs a level up. A specialized subsection on the origin and development of racism in Europe should be referenced from the European history section. However, in the times of slavetade and colonialism, European racism contributed a lot to the destruction of other parts of the world, so at least the Western type of racism has some world wide relevance.Nannus 23:59, 26 February 2007 (UTC)
 * One more thought about this: nothing forces us to build a strict hierarchy. In a physical university, you have to put everything into just one place, but here we have a hypertext medium. Something may be linked from European History, African History, Chinese History etc. at the same time if it contains stuff relevant for all of them. That is the reason why I did not call this a "Department", but an "Institute", meaning that it is not a subdivision of any of the Departments or Schools it is linked from. Maybe this should be indicated more clearly on the pages where it is referenced. One additional advantage of linking it from many pages is that it might get some attention. Nannus 20:58, 27 February 2007 (UTC)
 * If every single project that has something to do with European History was linked to from the European Department page, we wouldn't need a History School page, because 90%+ of everything would be in the European Department page (and it would eventually get quite cluttered). Individual materials relevant to European History should be listed there.  This Institute, however, doesn't really belong there—it just belongs under History.  European racism certainly affected the world, but not necessarily to a greater degree than Middle Eastern (semitic) racism—it factored significantly into Islam, and the Old Testament/Tanakh is rife with it (and it is arguably this which much European racism is founded on).  Ultimately, global topics like this belong directly in the School of History, not under its subdepartments.  If you want attention, I recommend posting on the talk page of various Departments, asking if contributors there would be willing/able to create projects related to your Institute.  The Jade Knight 08:50, 10 March 2007 (UTC)

Proposed Move
It has been proposed that this Department be moved to simply History of Racism, as it does not appear to have enough content to warrant Topic space. Any objections? The Jade Knight (d'viser) 03:56, 16 October 2008 (UTC)

title: Talk:Racism/History


text:
Earth Station/Alpha

Alpha
Margie saw the suit on her sister for the first time. It made her look like a completely different person than the one that taught her to play _______ and Helped her climb the big _hickory_ out back. When the _drafter_ came to pick her up, she could hardly believe it was her own older sibling about to go fight the _______ at the outskirts. But there she was. The bold primary colors of the uniform reminded her of the squad that saved her very life, indeed the lives of many in _______ just a few years earlier. Most 7-year-olds had similar memories of the battle.

title: Earth Station/Alpha


text:
Wikiversity talk:Motto contest/Round 5

Layout Idea
Hi. I don't want to sound preachy or anything, and I personally don't really mind what the motto or slogan for Wikiversity is; but wouldn't it be easier if, rather than the current systemy ou seem to have, which is very confusing to read, would it be easier to have like a simple voting system? For example:

Created by: _ _ _
 * Set Learing Free

Number of Votes:

Click Here for a list of the people/users who have voted for this motto.

Created by: _ _ _
 * Bringing Learning to Life

Number of Votes:

Click Here for a list of the people/users who have voted for this motto.

And so on.

The Closing date for the Motto/Slogan competition is the 1st of April. Remember, your votes counts, and will shape the way that Wikiversity is viewed by the rest of the world. So choose carefully.

Just an idea, to make the current page easier to read. I didn't want to do it, because I didn't want to step on anybody's toes; and I'm not familiar with wiki-formatting.

Tom S.

title: Wikiversity talk:Motto contest/Round 5


text:
Talk:CisLunarFreighter/UML case diagrams

I've started an Earth Station series. Earth Station/Alpha sets up two actors, Marge and her 12-year-old big sister. Marge is code for "margin" because she begins on a constraint boundary in the UML Model. In the case diagram, her role is established within the margin at the upper left-hand corner of the 2-dimentional representation. -- CQ 16:18, 25 February 2007 (UTC)