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Calculus/Definite integral

Suppose we are given a function and would like to determine the area underneath its graph over an interval. We could guess, but how could we figure out the exact area? Below, using a few clever ideas, we actually define such an area and show that by using what is called the definite integral we can indeed determine the exact area underneath a curve.

Definition of the Definite Integral

The rough idea of defining the area under the graph of $$f$$ is to approximate this area with a finite number of rectangles. Since we can easily work out the area of the rectangles, we get an estimate of the area under the graph. If we use a larger number of smaller-sized rectangles we expect greater accuracy with respect to the area under the curve and hence a better approximation. Somehow, it seems that we could use our old friend from differentiation, the limit, and "approach" an infinite number of rectangles to get the exact area. Let's look at such an idea more closely.

Suppose we have a function $$f$$ that is positive on the interval $$[a,b]$$ and we want to find the area $$S$$ under $$f$$ between $$a$$ and $$b$$. Let's pick an integer $$n$$ and divide the interval into $$n$$ subintervals of equal width (see Figure 1). As the interval $$[a,b]$$ has width $$b-a$$, each subinterval has width $$\Delta x=\frac{b-a}{n}$$. We denote the endpoints of the subintervals by $$x_0,x_1,\ldots,x_n$$. This gives us
 * $$x_i=a+i\Delta x\text{ for }i=0,1,\dots,n$$

Now for each $$i=1,\ldots,n$$ pick a sample point $$x_i^*$$ in the interval $$[x_{i-1},x_i]$$ and consider the rectangle of height $$f(x_i^*)$$ and width $$\Delta x$$ (see Figure 2). The area of this rectangle is $$f(x_i^*)\Delta x$$. By adding up the area of all the rectangles for $$i=1,\ldots,n$$ we get that the area $$S$$ is approximated by
 * $$A_n=f(x_1^*)\Delta x+\dots+f(x_n^*)\Delta x$$

A more convenient way to write this is with summation notation:
 * $$A_n=\sum_{i=1}^n f(x_i^*)\Delta x$$

For each number $$n$$ we get a different approximation. As $$n$$ gets larger the width of the rectangles gets smaller which yields a better approximation (see Figure 3). In the limit of $$A_n$$ as $$n$$ tends to infinity we get the area $$S$$.

It is a fact that if $$f$$ is continuous on $$[a,b]$$ then this limit always exists and does not depend on the choice of the points $$x_i^*\in[x_{i-1},x_i]$$. For instance they may be evenly spaced, or distributed ambiguously throughout the interval. The proof of this is technical and is beyond the scope of this section.

One important feature of this definition is that we also allow functions which take negative values. If $$f(x)<0$$ for all $$x$$ then $$f(x_i^*)<0$$ so $$f(x_i^*)\Delta x<0$$. So the definite integral of $$f$$ will be strictly negative. More generally if $$f$$ takes on both positive and negative values then $$\int\limits_a^b f(x)dx$$ will be the area under the positive part of the graph of $$f$$ minus the area above the graph of the negative part of the graph (see Figure 4). For this reason we say that $$\int\limits_a^b f(x)dx$$ is the signed area under the graph.

Independence of Variable
It is important to notice that the variable $$x$$ did not play an important role in the definition of the integral. In fact we can replace it with any other letter, so the following are all equal:
 * $$\int\limits_a^b f(x)dx=\int\limits_a^b f(t)dt=\int\limits_a^b f(u)du=\int\limits_a^b f(w)dw$$

Each of these is the signed area under the graph of $$f$$ between $$a$$ and $$b$$. Such a variable is often referred to as a dummy variable or a bound variable.

Left and Right Handed Riemann Sums
The following methods are sometimes referred to as L-RAM and R-RAM, RAM standing for "Rectangular Approximation Method."

We could have decided to choose all our sample points $$x_i^*$$ to be on the right hand side of the interval $$[x_{i-1},x_i]$$ (see Figure 5). Then $$x_i^*=x_i$$ for all $$i$$ and the approximation that we called $$A_n$$ for the area becomes
 * $$A_n=\sum_{i=1}^n f(x_i)\Delta x$$

This is called the right-handed Riemann sum, and the integral is the limit
 * $$\int\limits_a^b f(x)dx=\lim_{n\to\infty}A_n=\lim_{n\to\infty}\sum_{i=1}^n f(x_i)\Delta x$$

Alternatively we could have taken each sample point on the left hand side of the interval. In this case $$x_i^*=x_{i-1}$$ (see Figure 6) and the approximation becomes
 * $$A_n=\sum_{i=1}^n f(x_{i-1})\Delta x$$

Then the integral of $$f$$ is
 * $$\int\limits_a^b f(x)dx=\lim_{n\to\infty}A_n=\lim_{n\to\infty}\sum_{i=1}^n f(x_{i-1})\Delta x$$

The key point is that, as long as $$f$$ is continuous, these two definitions give the same answer for the integral.

Examples
Example 1 In this example we will calculate the area under the curve given by the graph of $$f(x)=x$$ for $$x$$ between 0 and 1. First we fix an integer $$n$$ and divide the interval $$[0,1]$$ into $$n$$ subintervals of equal width. So each subinterval has width
 * $$\Delta x=\frac{1}{n}$$

To calculate the integral we will use the right-handed Riemann sum. (We could have used the left-handed sum instead, and this would give the same answer in the end). For the right-handed sum the sample points are
 * $$x_i^*=0+i\Delta x=\frac{i}{n}\quad i=1,\ldots,n$$

Notice that $$f(x_i^*)=x_i^*=\frac{i}{n}$$. Putting this into the formula for the approximation,
 * $$A_n=\sum_{i=1}^n f(x_{i}^*)\Delta x=\sum_{i=1}^n f\left(\frac{i}{n}\right)\Delta x=\sum_{i=1}^n \frac{i}{n}\cdot\frac{1}{n}=\frac{1}{n^2}\sum_{i=1}^n i$$

Now we use the formula
 * $$\sum_{i=1}^n i=\frac{n(n+1)}{2}$$

to get
 * $$A_n=\frac{1}{n^2}\cdot\frac{n(n+1)}{2}=\frac{n+1}{2n}$$

To calculate the integral of $$f$$ between $$0$$ and $$1$$ we take the limit as $$n$$ tends to infinity,
 * $$\int\limits_0^1 f(x)dx=\lim_{n\to\infty}\frac{n+1}{2n}=\frac{1}{2}$$

Example 2 Next we show how to find the integral of the function $$f(x)=x^2$$ between $$x=a$$ and $$x=b$$. This time the interval $$[a,b]$$ has width $$b-a$$ so
 * $$\Delta x=\frac{b-a}{n}$$

Once again we will use the right-handed Riemann sum. So the sample points we choose are
 * $$x_i^*=a+i\Delta x=a+\frac{i(b-a)}{n}$$

Thus

We have to calculate each piece on the right hand side of this equation. For the first two,
 * $$A_n$$
 * $$=\sum_{i=1}^n f(x_{i}^*)\Delta x$$
 * $$=\sum_{i=1}^n f\left(a+\frac{(b-a)i}{n}\right)\Delta x$$
 * $$=\frac{b-a}{n}\sum_{i=1}^n \left(a+\frac{(b-a)i}{n}\right)^2$$
 * $$=\frac{b-a}{n}\sum_{i=1}^n \left(a^2+\frac{2a(b-a)i}{n}+\frac{(b-a)^2i^2}{n^2}\right)$$
 * }
 * $$=\frac{b-a}{n}\sum_{i=1}^n \left(a+\frac{(b-a)i}{n}\right)^2$$
 * $$=\frac{b-a}{n}\sum_{i=1}^n \left(a^2+\frac{2a(b-a)i}{n}+\frac{(b-a)^2i^2}{n^2}\right)$$
 * }
 * $$=\frac{b-a}{n}\sum_{i=1}^n \left(a^2+\frac{2a(b-a)i}{n}+\frac{(b-a)^2i^2}{n^2}\right)$$
 * }
 * }
 * $$\sum_{i=1}^n a^2=a^2\sum_{i=1}^n 1=na^2$$
 * $$\sum_{i=1}^n \frac{2a(b-a)i}{n}=\frac{2a(b-a)}{n}\sum_{i=1}^n i=\frac{2a(b-a)}{n}\cdot\frac{n(n+1)}{2}$$

For the third sum we have to use a formula
 * $$\sum_{i=1}^n i^2=\frac{n(n+1)(2n+1)}{6}$$

to get
 * $$\sum_{i=1}^n \frac{(b-a)^2i^2}{n^2}=\frac{(b-a)^2}{n^2}\frac{n(n+1)(2n+1)}{6}$$

Putting this together
 * $$A_n=\frac{b-a}{n}\left(na^2+\frac{2a(b-a)}{n}\cdot\frac{n(n+1)}{2}+\frac{(b-a)^2}{n^2}\frac{n(n+1)(2n+1)}{6}\right)$$

Taking the limit as $$n$$ tend to infinity gives

 * $$\int\limits_a^b x^2dx$$
 * $$=(b-a)\left(a^2+a(b-a)+\frac{1}{3}(b-a)^2\right)$$
 * $$=(b-a)\left(a^2+ab-a^2+\frac{1}{3}(b^2-2ab+a^2)\right) $$
 * $$=\frac{1}{3}(b-a)(b^2+ab+a^2)$$
 * $$=\frac{1}{3}(b^3-a^3)$$
 * }
 * $$=\frac{1}{3}(b-a)(b^2+ab+a^2)$$
 * $$=\frac{1}{3}(b^3-a^3)$$
 * }
 * $$=\frac{1}{3}(b^3-a^3)$$
 * }
 * }

Basic Properties of the Integral
From the definition of the integral we can deduce some basic properties. For all the following rules, suppose that $$f$$ and $$g$$ are continuous on $$[a,b]$$.

The Constant Rule
When $$f$$ is positive, the height of the function $$c\cdot f$$ at a point $$x$$ is $$c$$ times the height of the function $$f$$. So the area under $$c\cdot f$$ between $$a$$ and $$b$$ is $$c$$ times the area under $$f$$. We can also give a proof using the definition of the integral, using the constant rule for limits,
 * $$\int\limits_a^b c\cdot f(x)dx=\lim_{n\to\infty}\sum_{i=1}^n c\cdot f(x_i^*)=c\cdot\lim_{n\to\infty}\sum_{i=1}^n f(x_i^*)=c\int\limits_a^b f(x)dx$$

Example

We saw in the previous section that
 * $$\int\limits_0^1 xdx=\frac{1}{2}$$

Using the constant rule we can use this to calculate that
 * $$\int\limits_0^1 3xdx=3\int\limits_0^1 xdx=3\cdot\frac{1}{2}=1.5$$ ,
 * $$\int\limits_0^1 -7xdx=-7\int\limits_0^1 xdx=(-7)\cdot\frac{1}{2}=-3.5$$.

Example

We saw in the previous section that
 * $$\int\limits_a^b x^2dx=\frac{b^3-a^3}{3}$$

We can use this and the constant rule to calculate that
 * $$\int\limits_1^3 2x^2 dx=2\int\limits_1^3 x^2dx=2\cdot\frac{1}{3}\cdot(3^3-1^3)=\frac{2}{3}(27-1)=\frac{52}{3}$$

There is a special case of this rule used for integrating constants:

When $$c>0$$ and $$a<b$$ this integral is the area of a rectangle of height $$c$$ and width $$b-a$$ which equals $$c(b-a)$$.

Example
 * $$\int\limits_1^3 9dx=9(3-1)=9\cdot 2=18$$
 * $$\int\limits_{-2}^6 11dx=11(6-(-2))=11\cdot 8=88$$
 * $$\int\limits_2^{17} 0dx=0\cdot(17-2)=0$$

The addition and subtraction rule
As with the constant rule, the addition rule follows from the addition rule for limits:

The subtraction rule can be proved in a similar way.
 * $$\int\limits_a^b \bigl(f(x)+g(x)\bigr)dx$$
 * $$=\lim_{n\to\infty}\sum_{i=1}^n \Big(f(x_i^*)+g(x_i^*)\Big)$$
 * $$=\lim_{n\to\infty}\sum_{i=1}^n f(x_i^*)+\lim_{n\to\infty}\sum_{i=1}^n g(x_i^*)$$
 * $$=\int\limits_a^b f(x)dx+\int\limits_a^b g(x)dx$$
 * }
 * $$=\int\limits_a^b f(x)dx+\int\limits_a^b g(x)dx$$
 * }
 * $$=\int\limits_a^b f(x)dx+\int\limits_a^b g(x)dx$$
 * }

Example

From above $$\int\limits_1^3 9dx=18$$ and $$\int\limits_1^3 2x^2dx=\frac{52}{3}$$ so
 * $$\int\limits_1^3 (2x^2+9)dx=\int\limits_1^3 2x^2dx+\int\limits_1^3 9dx=\frac{52}{3}+18=\frac{106}{3}$$
 * $$\int\limits_1^3 (2x^2-9)dx=\int\limits_1^3 2x^2dx-\int\limits_1^3 9dx=\frac{52}{3}-18=-\frac{2}{3}$$

Example
 * $$\int\limits_0^2 (4x^2+14)dx=4\int\limits_0^2 x^2dx+\int\limits_0^2 14dx=4\cdot\frac{1}{3}(2^3-0^3)+2\cdot 14=\frac{32}{3}+28=\frac{116}{3}$$

The Comparison Rule

If $$f(x)\ge 0$$ then each of the rectangles in the Riemann sum to calculate the integral of $$f$$ will be above the $$y$$ axis, so the area will be non-negative. If $$f(x)\ge g(x)$$ then $$f(x)-g(x)\ge 0$$ and by the first property we get the second property. Finally if $$M\ge f(x)\ge m$$ then the area under the graph of $$f$$ will be greater than the area of rectangle with height $$m$$ and less than the area of the rectangle with height $$M$$ (see Figure 7). So
 * $$M(b-a)=\int\limits_a^b M\ge\int\limits_a^b f(x)dx\ge\int\limits_a^b m=m(b-a)$$

Linearity with respect to endpoints
Again suppose that $$f$$ is positive. Then this property should be interpreted as saying that the area under the graph of $$f$$ between $$a$$ and $$b$$ is the area between $$a$$ and $$c$$ plus the area between $$c$$ and $$b$$ (see Figure 8).

Even and odd functions
Recall that a function $$f$$ is called odd if it satisfies $$f(-x)=-f(x)$$ and is called even if $$f(-x)=f(x)$$.

Suppose $$f$$ is an odd function and consider first just the integral from $$-a$$ to $$0$$. We make the substitution $$u=-x$$ so $$du=-dx$$. Notice that if $$x=-a$$ then $$u=a$$ and if $$x=0$$ then $$u=0$$. Hence
 * $$\int\limits_{-a}^0 f(x)dx=-\int\limits_a^0 f(-u)du=\int\limits_0^a f(-u)du$$.

Now as $$f$$ is odd, $$ f(-u)=-f(u)$$ so the integral becomes
 * $$\int\limits_{-a}^0 f(x)dx=-\int\limits_0^a f(u) du$$.

Now we can replace the dummy variable $$u$$ with any other variable. So we can replace it with the letter $$x$$ to give
 * $$\int\limits_{-a}^0 f(x)dx=-\int\limits_0^a f(u)du=-\int\limits_0^a f(x)dx$$.

Now we split the integral into two pieces
 * $$\int\limits_{-a}^a f(x)dx=\int\limits_{-a}^0 f(x)dx+\int\limits_0^a f(x)dx=-\int\limits_0^a f(x)dx+\int\limits_0^a f(x)dx=0$$.

The proof of the formula for even functions is similar.

title: Calculus/Definite integral


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User:Kellen/Scratch/Uncategorized

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Microbiology/The 3 Domains of Life

The three Domains of organisms are:

Domain Archaea, which consists of the Archaeans, or extremophiles.

Domain Bacteria, which consists of all the bacteria.

Domain Eukarya, which consists of all eukaryotic organisms, or those with the largest, most complex cells and the most advanced compartmentalization.

title: Microbiology/The 3 Domains of Life


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Cookbook:Kugelis (Lithuanian Baked Potato Pudding)

| Cuisine of Lithuania

Kugelis, also called bulvių plokštainis (literally "flat potato dish") or banda, is a Lithuanian baked potato pudding. Its main ingredients are potatoes, bacon, milk, onions, and eggs. It may be spiced with salt, black pepper, bay leaves, and/or marjoram. It is usually eaten with sour cream and/or crumbled fried fat white bacon (spirgai).

Ingredients

 * 5 lb potatoes, peeled and grated (or ground with a food processor)
 * 2 medium onions, grated
 * 1 lb bacon, fried and crumbled (reserve about ¼ cup drippings)
 * 1 stick (8 tbsp) butter, melted
 * 6 eggs
 * 1 large can evaporated milk
 * 4 tsp salt
 * Pepper to taste (about 1 tsp)

Procedure

 * 1) Combine the grated potatoes and onions.
 * 2) Fry and crumble bacon. Add to the potato mixture along with ¼ cup bacon fat. Mix well.
 * 3) Beat the eggs, and stir in the evaporated milk, melted butter, salt, and pepper.
 * 4) Mix the egg mixture into the potato mixture.
 * 5) Pour into a well-greased 9x13-inch cake pan—it should just barely fit.
 * 6) Bake at 350°F (175°C) for 90 minutes.
 * 7) Slice into squares, and top with sour cream or applesauce.

Notes, tips, and variations

 * Leftovers are best reheated sliced thin and sautéed in melted butter. Kugelis also reheats well in the microwave and freezes well.
 * Do not drain the liquid from the potatoes and onions.


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Template talk:User firefox

The logo used before has been deleted from Commons as a derivative work. A sugested replacement logo is /Lokal_Profil 13:03, 25 October 2006 (UTC)

title: Template talk:User firefox


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Talk:Character Creation

very, very bad wikibook. --85.97.28.57 13:52, 25 October 2006 (UTC)

and it has been around since 25 october 2006 without being edited or deleted?--Nim 19:23, 1 August 2007 (UTC)

Said the people who are too lazy to even attempt to edit this wikibook and make it valuable. Thank you for your dedication to wikibooks. ~VNinja~ 13:54, 13 June 2008 (UTC)

 * A common problem. Anyway, I've had a go at expanding and developing this, hopefully people will be happier. Unusual? Quite TalkQu 22:45, 25 December 2008 (UTC)

Bravery, a important character trait?
Is bravery a important character trait, or the only important character trait? In a fictional story intended for children, and young adults, a heroic character is the only type of protagonist I'll buy for children. I think this is a great point. Peyton09 (discuss • contribs) 02:35, 20 May 2020 (UTC)

title: Talk:Character Creation


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XForms/Versioning Form Data With WebDAV and Subversion

Motivation
Users frequently want multi-versioned forms. This means that they not only want to keep prior versions of a form's instance data but they also want to:

 * be able to view prior versions
 * compare the current version with a prior version
 * see who changed what fields on a form an when
 * revert to a prior version

This problem frequently occurs in complex computer systems that have configuration files. Something stops working but people don't notice it till later. There is no information about what the prior versions of configuration file looked like so the entire systems must be restored from backups. Many of these problems could be avoided by automatically reverting to the prior version of a configuration file.

Background
With the XForms standard we are given the element and a small list of HTTP operators (GET, PUT, POST) to use and an action that can be any URL. If we want to allow users to save form data to a version-control system or to see prior versions of a form we have to translate these operations into something that a web server will recognize as operations on a version-control database.

Subversion is an open-source version control system with a client/server architecture (as opposed to a file-based architecture typical of other version controls systems).

Unlike older file-based version control systems, Subversion uses a transaction server model similar those used for reliable banking transactions. This makes subversion very reliable and allows you to check-in (or commit) groups of files that should be checked in together. They will either all succeed or all fail but the version controls system is guaranteed to always be in a consistent state.

Subversion also conforms (where it can) to the WebDAV WebDAV stands for Web Distributed Authoring and Versioning specification. The standard web HTTP protocol supports just a few operations such as get, put and post. WebDAV extends these simple operations to include operations we might expect on a file system such as delete, move and copy. Since WebDAV is more about file operations and Subversion is more centered on transactions, sometimes there is not an exact fit between the two.

Subversion has two principal concepts:
 * update - gets the latest version of your code from the server.
 * commit - take all the files you have changed from your local file system and save the changes through a transaction on the server.

To allow forms data to save to subversion we need to make a submission element do a commit. This is not necessarily hard but we want to be clear how the systems are different.

Subversion, WebDAV
Subversion is a version control database. At its core, it does not include an independent access control system. Because it is usually installed as part of a web server it usually uses the access control system of the web server it runs on. Apache also supports the WebDAV HTTP extensions which allow complex operations beyond the basic HTTP get, put and post. One of the best ways to get XForms to be persistent is to configure Apache to use WebDAV with

Autoversioning and Apache
To configure autoversioning with Apache2 server you must modify the configuration file. This file should be configured to support your XForms work.

WARNING!: Any time you allow public access to write to your server you are dealing with security issues. You should always consider ALL of the security implications before you make ANY changes to a web servers configuration file. Make sure that security professional in your organization review any systems that have public web access.

You will want to have an Apache configuration similar to the following somewhat half-XMLish format:

 DAV svn SVNPath /var/svnrepos SVNAutoversioning on    Require valid-user

See also the well-written chapter of the Subversion Red Book or the respective excellent Gentoo 's Apache-SVN-WebDAV-HOWTO section for detailed configuration help with examples.

Converting HTTP PUT into Subversion Submit
The last step is to convert HTTP PUT into a subversion COMMIT. This can be accomplished using a program such as Jetty.

(We will post a sample program soon).

ViewCV and ReST
You can also start to add tools to Apache and Subversion to get colorful output that shows the differences between prior files. One option is to add the ViewVC (View Version Control) system to your Apache server. ViewVC allows you to see version history can compare prior versions just by addeing parameters to the URL. This method of using the URL to pass parameters to a server program is frequently called a REST interface. Almost all REST interfaces are easy to interface with XForms since XForms can encode the submission instances directly onto the URL.

Subversion REST URL interface
Subversion allows you to access a resource's version history by adding an additional path to the URL. See

For example if your file name was

http://www.example.com/my-repository/myfile.xml

If you wanted to get version 47 of a file it might be:

http://www.example.com/my-repository/!svn/ver/47/myfile.xml

Debugging Tips
The Subversion FAQ suggests you run the Wireshark packet sniffer and look at the data in the HTTP messages. You can also use the Charles Web debugging proxy which also has a nice FireFox plug-in. Just make sure you know how to disable the proxy by going to the Firefox Tools/Options/General/Connection Settings and click the Direction Connection to the Internet. If you do not your web browser will no longer function when Charles shuts down.


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Adventist Youth Honors Answer Book/Knot/Sheetbend

/Transcluded Modules


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Adventist Youth Honors Answer Book/Knot/Sheepshank

/Transcluded Modules


text: Adventist Youth Honors Answer Book/Knot/Surgeons


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Nets, Webs and the Information Infrastructure/Viruses, Privacy and Security

What is a virus?
PCWebopedia (http://www.webopedia.com) defines a computer virus as “a program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves.”

The term virus has become a catch-all name for all malicious computer programs. Strictly speaking, a virus is a type of electronic infection. The most common forms of infection are the email virus, worm and trojan program.

An email virus moves around in email messages, and usually replicates by automatically mailing itself to the addresses in the victim’s email address book.

A worm infiltrates existing computer networks through security holes. It uses the network to scan for other computers where the worm can reside and replicate itself.

A trojan program is a computer program that claims to do one thing (e.g., it claims to be a game) while taking other actions that the user is not aware of (e.g., copying and sending files to another computer). Trojan programs usually do not replicate automatically. Their activities may range from erasing or modifying files, sending email, or sending private information through the Internet.

Why do virus outbreaks cost companies money?
The following are some of the ways that virus outbreaks increase company expenditures:

Computer breakdowns. Viruses are capable of crippling a computer by erasing or changing important files. They can clog networks, resulting in delays in legitimate computing tasks. This reduces productivity.

Virus cleanup required. When a computer is infected by a virus, the expertise of IT personnel is required to get rid of the virus. Some companies call in IT experts to remove viruses. Other companies choose to employ full time personnel to troubleshoot and guard their system against virus outbreaks.

Lost data / Data recovery. There are instances when data is lost due to a virus outbreak. This data will need to be rebuilt or gathered again.

Security measures. Companies devote a portion of their IT budgets to prevent virus contamination of their networks. This means investments in anti-virus and other security software or hardware.

How can technology prevent virus outbreaks?
Virus infections can be prevented through a combination of good anti-virus software and good user habits.

Virus scanning - Scanning refers to the inspection of computer data to check whether there are viruses. Some scanning software inspect data as they are being introduced to a computer.

Common sense - The most effective defense against viruses are a person’s habits in using the computer. For example, users shouldn’t download email attachments without scanning them for viruses.

Virus fix - A virus fix is run on an infected computer to repair any damage caused by a virus. Virus fixes are the result of studying the effects of a virus on a computer. Thus, by its very nature, a virus fix becomes available only after a new virus is reported.

What are cookies?
In the Internet realm, a cookie is a message stored by a Web site in a user’s computer. It contains information that a Web site can retrieve when the user re-visits the Web site. During the user’s subsequent visits, the appearance of the Web site is adjusted based on the information that is “remembered” by the cookie. (Strictly speaking, because the cookie is stored in the computer, the Web site “remembers” the computer and not the user.)

Cookies work like a doctor entering data into a patient’s card. When the patient returns to the doctor, information about the patient’s previous visits helps the doctor provide better service to the patient.

What information is stored in cookies?
Cookies can store login information so that users do not need to type in this information every time they return to a site. Cookies can also determine the interests of a particular user by the sequence of sites that the user visits, by the information the user submits, or by the topics that the user chooses to view. Cookies can also store data about an ongoing transaction in order to continue the transaction at a later time.

For example, an online shopper, Almira, goes to an online bookstore (like Amazon.com) to buy a book about Elvis Presley. Almira will have a virtual shopping cart where she can store books related to Elvis. Cookies are used to store data for the shopping cart. Using cookies, the Web site may also recommend a compact disc of Elvis’s songs or movies by Elvis. Almira may see advertisements about other popular 70’s record albums on sale or travel tours featuring a trip to an Elvis museum or Web sites selling Elvis memorabilia. These are all based on the cookies’ perception of Almira’s interest in Elvis as shown by her search for a book about Elvis. Lastly, if Almira chooses to postpone her purchase, the cookie will store data so that when she comes back to continue her shopping, the books or other items she had left in her virtual shopping cart will still be there.

How can cookies become a privacy breach?
Cookies gather information to help make things convenient for a user. But when information is directly identifiable to a particular person and is used for purposes other than a user’s convenience, there could be a privacy breach.

Going back to the analogy of cookies acting like a patient’s card, if the doctor began to divulge information about the patient to a third party (e.g., to health insurance or pharmaceutical companies), the person’s privacy would be compromised. In Almira’s case, her privacy is breached when information gathered by the online bookstore is sold to other vendors.

There is a privacy breach when a Web site does not inform the user about the kind of information stored in a cookie and how this information is used.

Can a cookie “read” other files in a computer?
No, cookies do not have access to files in a person’s computer. Neither can cookies spread viruses. The only information available to cookies is information that has been divulged by the user such as his/her name, address, and credit card number. The privacy policy of a Web site is relevant here. In privacy statements, a Web site should state how they handle information exchanged between their Web site and a visitor’s computer.

What is a privacy policy? Why is it important?
A privacy policy is a declaration by Web sites or corporations that informs visitors about the kind of information gathered on the site and how this information is used. It states how the Web site protects the privacy of the visitor.

According to a study by Forrester Research, Inc., 90% of Web sites fail to comply with basic privacy principles. Also, the vast majority of such policies use vague terms and legal jargon that serve to protect companies and not individuals. The study showed that only about 10% of the companies studied adequately addressed the basic privacy of users.

How should governments handle online privacy problems?

There are four general approaches to privacy problems: laissez-faire, self-regulation, technology, and legislation/government.

Laissez-faire or “hands off” refers to the principle that governments need not regulate the marketplace, as the marketplace is guided by an “invisible hand” toward the most ideal balance of supply and demand. In the context of online privacy, the laissez-faire approach states that if people really feel concerned about their privacy, they will visit only Web sites with a clearly defined privacy policy. If the number of hits for Web sites with no or with inadequate privacy policy actually decreases as a consequence, this development would goad these Web sites to improve online privacy. In this scenario, consumer action defines the level of privacy protection that the consumers get.

Industry self-regulation is where there is cooperation and agreement between sectors in the industry regarding what is appropriate privacy policy. The policy will be based on recommendations of industry experts that balance the needs of businesses and consumers. Some tools for the implementation of industry self-regulation are seal programs, industry guidelines, and privacy organizations.

For example, the World Wide Web Consortium (W3C; www.w3c.org) has developed a privacy standard called Platform for Privacy Preferences Project (P3P). The W3C was created to help realize the Web’s full potential by developing common protocols that promote its evolution and ensure its interoperability. Simply stated, P3P lets a user declare a set of customized privacy rules. These rules will be used to determine whether or not a Web site has acceptable privacy policies. Software based on P3P will help a user determine the actions to be taken when a Web site’s privacy policies do not match the user’s privacy rules.

Technology is a solution that can be taken up by private individuals, enterprises and interest groups. Many of the technology solutions involve working with browsers which inform a user of the privacy levels upheld by the Web site being visited.

 * Box 3. Examples of P3P Tools

Technology and industry standards have become complimentary solutions to privacy issues. For example, there are tools developed based on P3P standards that automatically look up the privacy statement of the Web site. If the Web site’s privacy policies are within the specified standards of the user, navigation of the site is continued. Otherwise, the user is informed of the level of privacy protection afforded by the Web site. This is all done automatically, with minimal intervention of the user, by embedding machine-readable codes that are read by P3P tools. Tools are being developed by companies independent of W3C, which encourages private companies to develop software that will enable the use of P3P.

Governments sometimes play an active role in protecting privacy on the Internet. Korea, for example, has been vigilant in protecting citizen privacy, promulgating the “Information Infrastructure Protection Act” and “The Act on Promotion of Utilization of Information and Communication Network and Data Protection” in 2001.

What kinds of privacy legislation have been passed?
A study of the privacy laws of 15 jurisdictions reveals the following:

 * Eleven jurisdictions impose restrictions on the transfer of data across borders. Only Brazil, Russia and the United States do not. Chinese law does not address cross-border data transfers.

 * Twelve jurisdictions have existing or proposed laws that address both traditional privacy and data protection. The privacy laws in Japan and Sweden are focused primarily on data protection.

 * Most of the jurisdictions require notice to the data-subject that data is being collected and its use, some form of consent by the subject for the data to be collected and used, protection of the subject’s right to access the data, and maintenance of data security by the data controller.

 * In all but three jurisdictions-Australia, Hong Kong and Japan-a data-subject may go to court to enforce privacy laws.

 * In 13 jurisdictions in the survey, violations of privacy law can be criminal.

 * Box 4. Fair Information Practices of the United States and the OECD

Sources: Jared Straus and Ken Rogerson, “Policies for Online Privacy in the United States and the European Union,” Regulating the Internet: EU & US Perspectives [home page online]; available from http://jsis.artsci.washington.edu/ programs/europe/Netconference/Strauss-RogersonPaper.htm; accessed 4 September 2002.

James S. Huggins, “OECD Privacy-D-Personal Data Privacy Goes International,” James S. Huggins’ Refrigerator Door [home page online]; available from http://www.jamesshuggins.com/h/bas1/oecd_privacy_d.htm; accessed 4 September 2002.

What are the security issues on the Internet?
The CERT Coordination Center (CERT/CC; http://www.cert.org), a center for Internet security expertise, has suggested that the increasing speed and sophistication of attack tools, faster discovery of vulnerabilities, and increasing permeability of firewalls are important trends related to Internet security.

Notably, there is an increasing threat from infrastructure attacks. There are four types of infrastructure attacks. The first type is Denial of Service (DoS) where excessive network traffic caused by malicious attacks crowd out legitimate users from using the network. The second type of attack is through worms, which are self-propagating malicious code such as “Code Red”, “Nimda” and “Klez”. The Code Red worm infected more than 250,000 systems in just nine hours. Third, attacks on the Internet domain name systems (DNS) can render Web sites inaccessible, vandalize legitimate Web sites or re-direct Web site traffic to the attacker’s Web site. Government and military Web sites are common targets of this kind of attacks. The fourth type consists of attacks against or using routers. Attacks on routers can result in interception of information or a slowing down of information delivery.

What measures can be taken to prevent computer cracking and other security breaches?
There are three countermeasures to threats of cracking: technology, people and policy.

Advances in technology continue to improve the security of computer systems. Software and hardware are being developed to guard against computer break-ins. Among the countermeasures that can be implemented are a secure DSL connection, installation of a personal firewall, installation of anti-virus software, safe email practices, and regular backups.

But technology is effective only until the next cracker discovers another security hole. Thus, it is important for people (security experts, programmers, administrators) to be able to effectively monitor a system. Especially when computers, networks or servers contain sensitive information, it is imperative that experts can protect the security of the system.

Lastly, policies for punishing crackers are important. Recently, new laws in cybercrime have been put to the test. Legislators are learning whether or not the laws effectively address cybercrimes. Read more about this in the primer on cyberlaw.

 * Definition

 * Box 5. Korea Information Security Agency

Korea Information Security Agency, “About Korea Information Security Agency,” KISA [home page online]; available from http://www.kisa.or.kr/english/about_kisa_01.html; accessed 18 September 2002.

Is there a conflict between national security and privacy of the citizen in the online world?
The challenge is to protect the privacy of citizens online without impairing the State’s right to examine documents and transmissions that threaten national security. The September 11 terrorist attacks in the USA introduced a new perspective into the Security of the State vs. Privacy of the Citizen debate. On the one hand, there is a continued campaign for the protection of personal privacy. On the other hand, governments (particularly the US government) have turned to information technology as a tool to combat terrorism.

In the years prior to the September 11 attack, financial institutions developed systems for securing direct mail, credit card offers and other kinds of targeted marketing. Other systems specifically targeted the detection of money-laundering activities. This involved the collection of millions of transactions from various financial institutions and identifying trends that appear suspicious. This sharing of information between financial institutions was dropped as it was considered by many as an encroachment of privacy. After September 11, however, “some specialists believe the scrutiny of consumers on the government’s behalf is going even deeper”.


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Control Systems/Linear System Solutions

State Equation Solutions
The state equation is a first-order linear differential equation, or (more precisely) a system of linear differential equations. Because this is a first-order equation, we can use results from Ordinary Differential Equations to find a general solution to the equation in terms of the state-variable x. Once the state equation has been solved for x, that solution can be plugged into the output equation. The resulting equation will show the direct relationship between the system input and the system output, without the need to account explicitly for the internal state of the system. The sections in this chapter will discuss the solutions to the state-space equations, starting with the easiest case (Time-invariant, no input), and ending with the most difficult case (Time-variant systems).

Solving for x(t) With Zero Input
Looking again at the state equation:

 * $$x' = Ax(t) + Bu(t)$$

We can see that this equation is a first-order differential equation, except that the variables are vectors, and the coefficients are matrices. However, because of the rules of matrix calculus, these distinctions don't matter. We can ignore the input term (for now), and rewrite this equation in the following form:

 * $$\frac{dx(t)}{dt} = Ax(t)$$

And we can separate out the variables as such:

 * $$\frac{dx(t)}{x(t)} = A dt$$

Integrating both sides, and raising both sides to a power of e, we obtain the result:

 * $$x(t) = e^{At+C}$$

Where C is a constant. We can assign D = eC to make the equation easier, but we also know that D will then be the initial conditions of the system. This becomes obvious if we plug the value zero into the variable t. The final solution to this equation then is given as:

 * $$x(t) = e^{A(t-t_0)}x(t_0)$$

We call the matrix exponential eAt the state-transition matrix, and calculating it, while difficult at times, is crucial to analyzing and manipulating systems. We will talk more about calculating the matrix exponential below.

Solving for x(t) With Non-Zero Input
If, however, our input is non-zero (as is generally the case with any interesting system), our solution is a little bit more complicated. Notice that now that we have our input term in the equation, we will no longer be able to separate the variables and integrate both sides easily.

 * $$x'(t) = Ax(t) + Bu(t)$$

We subtract to get the $$Ax(t)$$ on the left side, and then we do something curious; we premultiply both sides by the inverse state transition matrix:

 * $$e^{-At}x'(t) - e^{-At}Ax(t) = e^{-At}Bu(t)$$

The rationale for this last step may seem fuzzy at best, so we will illustrate the point with an example:

Example
Using the result from our example, we can condense the left side of our equation into a derivative:

 * $$\frac{d(e^{-At}x(t))}{dt} = e^{-At}Bu(t)$$

Now we can integrate both sides, from the initial time (t0) to the current time (t), using a dummy variable τ, we will get closer to our result. Finally, if we premultiply by eAt, we get our final result:

 * $$x(t) = e^{A(t-t_0)}x(t_0) + \int_{t_0}^{t}e^{A(t - \tau)}Bu(\tau)d\tau$$

If we plug this solution into the output equation, we get:

 * $$y(t) = Ce^{A(t-t_0)}x(t_0) + C\int_{t_0}^{t}e^{A(t - \tau)}Bu(\tau)d\tau + Du(t)$$

This is the general Time-Invariant solution to the state space equations, with non-zero input. These equations are important results, and students who are interested in a further study of control systems would do well to memorize these equations.

State-Transition Matrix
The state transition matrix, eAt, is an important part of the general state-space solutions for the time-invariant cases listed above. Calculating this matrix exponential function is one of the very first things that should be done when analyzing a new system, and the results of that calculation will tell important information about the system in question.

The matrix exponential can be calculated directly by using a Taylor-Series expansion:

 * $$e^{At} = \sum_{n=0}^\infty \frac{(At)^n}{n!}$$

Also, we can attempt to diagonalize the matrix A into a diagonal matrix or a Jordan Canonical matrix. The exponential of a diagonal matrix is simply the diagonal elements individually raised to that exponential. The exponential of a Jordan canonical matrix is slightly more complicated, but there is a useful pattern that can be exploited to find the solution quickly. Interested readers should read the relevant passages in Engineering Analysis.

The state transition matrix, and matrix exponentials in general are very important tools in control engineering.

Diagonal Matrices
If a matrix is diagonal, the state transition matrix can be calculated by raising each diagonal entry of the matrix raised as a power of e.

Jordan Canonical Form
If the A matrix is in the Jordan Canonical form, then the matrix exponential can be generated quickly using the following formula:

 * $$e^{Jt} = e^{\lambda t} \begin{bmatrix} 1 & t & \frac{1}{2!}t^2 & \cdots & \frac{1}{n!}t^n \\0 & 1 & t & \cdots & \frac{1}{(n-1)!}t^{n-1} \\ \vdots & \vdots & \vdots & \ddots & \vdots \\ 0 & 0 & 0 & \cdots & 1\end{bmatrix}$$

Where λ is the eigenvalue (the value on the diagonal) of the jordan-canonical matrix.

Inverse Laplace Method
We can calculate the state-transition matrix (or any matrix exponential function) by taking the following inverse Laplace transform:

 * $$e^{At} = \mathcal{L}^{-1}[(sI - A)^{-1}]$$

If A is a high-order matrix, this inverse can be difficult to solve.

If the A matrix is in the Jordan Canonical form, then the matrix exponential can be generated quickly using the following formula:

$$e^{Jt} = e^{\lambda t} \begin{bmatrix} 1 & t & \frac{1}{2!}t^2 & \cdots & \frac{1}{n!}t^n \\0 & 1 & t & \cdots & \frac{1}{(n-1)!}t^{n-1} \\ \vdots & \vdots & \vdots & \ddots & \vdots \\ 0 & 0 & 0 & \cdots & 1\end{bmatrix}$$

Where λ is the eigenvalue (the value on the diagonal) of the jordan-canonical matrix.

Spectral Decomposition
If we know all the eigenvalues of A, we can create our transition matrix T, and our inverse transition matrix T-1 These matrices will be the matrices of the right and left eigenvectors, respectively. If we have both the left and the right eigenvectors, we can calculate the state-transition matrix as:

 * $$ e^{At} = \sum_{i = 1}^ne^{\lambda_i t} v_i w_i'$$

Note that wi'  is the transpose of the ith left-eigenvector, not the derivative of it. We will discuss the concepts of "eigenvalues", "eigenvectors", and the technique of spectral decomposition in more detail in a later chapter.

Cayley-Hamilton Theorem
The Cayley-Hamilton Theorem can also be used to find a solution for a matrix exponential. For any eigenvalue of the system matrix A, λ, we can show that the two equations are equivalent:

 * $$e^{\lambda t} = a_0 + a_1 \lambda t + a_2 \lambda^2t^2 + \cdots + a_{n-1}\lambda^{n-1}t^{n-1}$$

Once we solve for the coefficients of the equation, a, we can then plug those coefficients into the following equation:

 * $$e^{At} = a_0I + a_1 A t + a_2 A^2 t^2 + \cdots + a_{n-1} A^{n-1} t^{n-1}$$

Example: Multiple Methods in MATLAB
תורת הבקרה/פתרון משוואת המצב עבור מערכת קבועה בזמן

title: Control Systems/Linear System Solutions


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Nets, Webs and the Information Infrastructure/For Further Reading

Information Infrastructure / Information & Communications Technologies
I Buy Broadband. 2002. “Broadband 101 - ISDN Frequently Asked Questions,” I Buy Broadband. Home page on-line. Available from https://www.ibuybroadband.com/ibb2/know-isdn.asp; Internet.

Naik, Dilip. 1998. Internet Standards and Protocols. Washington: Microsoft Press.

Palm.com. 2002. “ Bluetooth(tm) Create Wireless Personal Area Networks,” Palm.com. Home page on-line. Available from http://www.palm.com/wireless/bluetooth/. Internet.

Sheldon, Tom. 2002. “Internet Organizations and Committees,” Linktionary. Available from http://www.linktionary.com/i/internet_organizations.html; Internet.

The Living Internet. 2002. “The Living Internet,” The Living Internet. Home page online. Available from http://livinginternet.com/; Internet.

Viruses, Privacy and Security
Brain, Marshall. 2002. “How Computer Viruses Work,” Howstuffworks. Home page on-line. Available from http://www.howstuffworks.com/virus.htm; Internet.

Computer Knowledge. 2002. “Virus history,” Computer Knowledge. Home page online. Available from http://www.cknow.com/vtutor/vthistory.htm; Internet.

Electronic Privacy Information Center. 2002. “EPIC Online Guide to Practical Privacy Tools,” Electronic Privacy Information Center. Home page on-line. Available from http://www.epic.org/privacy/tools.html; Internet.

Electronic Privacy Information Center. 2002. “Cookies,” Electronic Privacy Information Center. Home page on-line. Available from http://www.epic.org/privacy/internet/ cookies/; Internet.

Huggins, James S. 2002. “Privacy Policy,” James S. Huggins. Home page on-line. Available from http://www.jamesshuggins.com/h/bas1/privacy.htm; Internet.

Lawson, Katherine T. 2002. “United States Internet Privacy Laws and the European Community Data Directive,” School of Information and Library Science. Available from http://www.ils.unc.edu/~lawsk/policypaper.html; Internet.

Platform for Privacy Preferences Initiative. 2002. “P3P 1.0: A New Standard in Online Privacy,” World Wide Web Consortium. Home page on-line. Available from http://www.w3.org/P3P/brochure.html; Internet.

Roziah, Sharifah. 2002. “Home PC Security,” National ICT Security & Emergency Response Centre. White paper on-line. Available from http://niser.org.my/resources/homepcsecurity.pdf; Internet.

Science Technology and Industry Directorate - OECD. 2002. “Information Security and Privacy,” Organisation for Economic Cooperation and Development. Home page on-line. Available from http://www.oecd.org/EN/relevant_links/0,,EN-relevant_links43-1-no-no-146-000.html; Internet.

Strauss, Jared and Ken Rogerson. 2002. “Policies for Online Privacy in the United States and the European Union,” University of Washington. Available from http://jsis.artsci.washington.edu/programs/europe/Netconference/Strauss-RogersonPaper.htm; Internet.

Tolman, Jarrett. 2002. “Computer Virus Timeline,” Information Please. Home page on-line. Available from http://www.infoplease.com/spot/virustime1.html; Internet.

White & Case News. 2002. “White & Case Privacy Law Survey Shows Rising Tide of Legal/Regulatory Controls in Major Countries Worldwide,” White & Case News. Home page on-line. Available from http://www.whitecase.com/pr_wc_privacy_law_survey.html; Internet.

Universal Service and Universal Access
Cairncross, Frances. 1997. The Death of Distance. Boston: Harvard Business School Press.

Benton Foundation. 2002. “The Benton Foundation’s Universal Service and Universal Access Virtual Library,” Benton Foundation. Home page on-line. Available from http://www.benton.org/Policy/Uniserv/; Internet.

Björn Wellenius. 1997. “Extending Telecommunications Service to Rural Areas-The Chilean Experience,” Public Policy for the Private Sector. Publication online. Available from http://www.worldbank.org/html/fpd/telecoms/pdf/ruralchi.pdf; Internet.

Global Information & Communication Technologies Department. 2002. GICT. Home page on-line. Available from http://info.worldbank.org/ict/; Internet.

Purdue Universal Access Initiative. 2002. “Purdue Universal Access Initiative - Web Developer’s Resources,” Purdue University. Home page on-line. Available from http://www.purdue.edu/odos/puai/; Internet.

Telecommunication Sector Reform Unit. 2002. “Documents & Reports : Universal Service,” International Telecommunication Union. Available from http://www.itu.int/ITU-D/treg/related-links/links-docs/uso.html; Internet.

UNESCO Observatory on the Information Society. 2002. “Universal Access Overview,” UNESCO. Home page on-line. http://www.unesco.org/webworld/observatory/doc_uni_access/index.shtml; Internet.

Wolf, Jason and Natalie Zee. 2001. The Last Mile - Broadband and the Next Internet Revolution. USA: McGraw-Hill.

Language
Language Technologies Institute. 2002. “LTI Projects,” Language Technologies Institute. Home page on-line. Available from http://www.lti.cs.cmu.edu/Research/cmtprojects.html; Internet.

Translate-free.com. 2002. “Foreign Language Translation Services Available Free on the Internet,” Translate-free.com. Links page on-line. Available from http://translatefree.com/; Internet.

Translation Journal. 2002. “Translation Journal,” Accurapid Translations. Home page on-line. Available from http://accurapid.com/journal/index.html; Internet.

Competition / Monopoly
Accenture, Markle Foundation, United Nations Development Programme. 2002. “Appendix 3 National ICT Approaches: Selected Case Studies,” Digital Opportunity Initiative. Home page on-line. Available from http://www.opt-init.org/framework/pages/appendix3Case2.html; Internet.

Stiglitz, Joseph. 2002. “Creating Competition in Telecommunications,” The World Bank Group. Home page on-line. Available from http://www.worldbank.org/html/extdr/extme/jssp042798.htm; Internet.

U. S. Department of Commerce - National Trade Data Bank. 2002. “Costa Rica: 1998 Country Report On Economic Policy and Trade Practices,” TradePort. Home page on-line. Available from http://www.tradeport.org/ts/countries/costarica/ecopol.html; Internet.

Internet History
Berners-Lee, Tim. 1999. Weaving the Web. New York: Harper San Francisco.

Berners-Lee, Tim. 2002. “The World Wide Web: A very short personal history,” World Wide Web Consortium. Home page on-line. Available from http://www.w3.org/People/Berners-Lee/ShortHistory.html; Internet.

Croatian Academic and Research Network. 2002. “History of The Internet,” Croatian Academic and Research Network. Home page on-line. Available from http://www.carnet.hr/internet/eng/world/index_eng.htm; Internet.

Griffiths, Richard T. 2002. “History of the Internet, Internet for Historians (and just about everyone else),” Universiteit Leiden. Home page online. Available from http://www.let.leidenuniv.nl/history/ivh/frame_theorie.html; Internet.

Internet Society. 2002. “All about the Internet: History of the Internet,” Internet Society. Home page on-line. Available from http://www.isoc.org/internet/history; Internet.

Zakon, Robert H. 2002. “Hobbes’ Internet Timeline,” Hobbes’ Internet Timeline. Home page on-line. Available from http://www.zakon.org/robert/internet/timeline/; Internet.

Figures
Figure 1. Schematic diagram by Edwin S. Soriano, digitally rendered by Corey Cruz ( http://geocities.com/mcxidesign).

Figure 2. Adapted from TeleGeography, “Major Interregional Internet Routes, 2001,” TeleGeography [home page online]; available from http://www.telegeography.com/resources/statistics/internet/pg02_major_internet_routes.html; accessed 18 September 2002.

Box 1 diagram. Adapted from Russ Haynal, “Schematic Diagram: Internet: ‘The Big Picture’,” Information Navigators [home page online]; available from http://navigators.com/internet_architecture.html; accessed 29 August 2002.

The Internet Time line. Adapted from “Hobbes’ Internet Timeline” Copyright (c) 19932003 by Robert H Zakon.

The cellular phone tower, fiber optic cable and satellite dish are building blocks of the global Internet infrastructure.

The cellular phone tower photograph is used with permission from EMF Services with website at http://www.emfservices.com.


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Nets, Webs and the Information Infrastructure/Glossary

Glossary
3G - Third Generation Wireless, wireless systems that provide high-speed data transmission (144kbps and higher). The system is equipped to handle regular mobile phone calls, short message service (SMS), email, Internet access and video.35

Bluetooth - a short-range wireless technology that links fixed or mobile devices such as mobile phones, PDAs, printers, audio players and other electronic appliances

Broadband - a type of data transfer in which a single wire can accommodate several data paths at once. Depending on the type of broadband connection, data speeds are from 2 to 20 times faster than ordinary dial-up connections.

Bug - an error or defect in software or hardware that causes a program to malfunction

Convergence - the coming together of two or more disparate disciplines or technologies

Cookie - a message stored by a Web site in a user’s computer so that the Web site can adjust its features to suit the user

Cracker - individuals who gain unauthorized access to computer systems for the purpose of stealing and corrupting data. See also Hacker.

Cybercrime - a criminal offense that has been created or made possible by the advent of computer technology36

Denial of Service (DoS) - a type of attack that floods a network with excessive traffic, rendering it useless to legitimate customers

DNS - Domain Name System; Domain Name Service

DVD - Digital Video Disk

Firewall - data protection device that restricts and controls the flow of data traffic between networks, typically between an internal corporate network and the Internet

FTP - File Transfer Protocol, a protocol for transferring files from one device (e.g., a workstation or a server) to another

Hacker - A slang term for a computer enthusiast, i.e., a person who enjoys learning programming languages and computer systems and who is often considered an expert on the subject(s). See also Cracker.

HTML - Hypertext Markup Language, the authoring language used to create documents on the World Wide Web

HTTP - Hypertext Transfer Protocol, the underlying protocol used by the World Wide Web

Infrared - light waves used to transmit data

Internet Explorer - A Web browser developed by Microsoft Corporation

ISDN - Integrated Services Digital Network, the international communications standard for sending voice, video, and data over digital telephone lines or normal telephone wires

ISP - Internet Service Provider, a company that provides access to the Internet

LAN - Local Area Network, a computer network that spans a relatively small area, typically a small office or home Last mile - the portion of the cable or telephone company that is wired directly to the customer’s home

Modem - Modulation/Demodulation, a device that enables a computer to transmit data over telephone lines

Netscape Navigator/Communicator - a Web browser that revolutionized the computer software market by giving away for free its popular Navigator Web browser, thus acquiring an overwhelming market share in the mid-1990s

OSS - open source software

P3P - Platform for Privacy Preferences (P3P) Project

PGP - Pretty Good Privacy

POTS - Plain Old Telephone Service

PSTN - Public Switched Telephone Network

Protocol - an agreed-upon format for transmitting data between two devices

Source Code - a computer program’s instructions in its original form

TCP/IP - Transmission Control Protocol / Internet Protocol

Telnet - allows users to log into remote computers and provides basic communication functions between computers

Telecenter - a public establishment that offers telecommunications services such as Internet access, landline or mobile phone calls, facsimile and video conferencing Unicode - a standard for representing characters as integers designed to support the worldwide interchange, processing, and display of the written texts of the diverse languages of the modern world

USB - Universal Serial Bus, a data communication standard that can be used to connect to computer peripherals such as a mouse, printer, modem, audio device, digital camera etc.

VSAT - Very Small Aperture Terminal, an earthbound station used in satellite communications of data, voice and video signals, excluding broadcast television

W3C - World Wide Web Consortium, an organization that develops interoperable specifications, guidelines, software, and tools for the Web (Web site: http://www.w3.org)

WAP - Wireless Application Protocol, a communication protocol that allows users to access information instantly via handheld wireless devices

WLAN - Wireless Local Area Network

Wireless - technologies that transmit data between devices without using connecting cables

XML - Extensible Markup Language


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User:Errantkid

My wikipedia userpage: Errantkid

title: User:Errantkid


text:
Cookbook:Sesame Oil

| Oils and Fats

Sesame oil is a rich, aromatic oil widely used in cooking across Asia, and to some degree throughout the Middle East. It is usually extracted after toasting the sesame seeds, which gives the oil a pleasant nutty flavor.

title: Cookbook:Sesame Oil


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Template:REVISIONMONTHNAME

Returns the revision month name of a page:

title: Template:REVISIONMONTHNAME


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Cookbook:Rocky Road Ice Cream

| USA | Ice Cream

Rocky road is a popular ice cream flavor in the United States. Though there are variations on the flavor, it is traditionally composed of chocolate ice cream, nuts and marshmallows. The flavor is claimed to have been created in 1929 by William Dreyer when he cut up almond and marshmallows with his wife's sewing scissors and added them to his chocolate ice cream during the Great Depression. The company claims it was then so named "to give folks something to smile about in the midst of the Great Depression."

Alternately, Fenton's Creamery in Oakland, California, claims that William Dreyer based his recipe on a Rocky Road ice cream invented by his friend, Fenton's George Farren, who blended his Rocky Road candy bar into ice cream; however Dreyer substituted pecans for almonds.

Ingredients

 * ⅓ cup (50 g / 1.8 oz) unsweetened cocoa powder
 * 1 cup (200 g / 7.1 oz) white granulated sugar
 * 2 cups (500 ml / 1 US pint) milk
 * 1 tbsp vanilla extract
 * 1 pinch of salt
 * 2 cups (450 ml / 15 oz) whipping cream
 * 1 oz (28 g) semisweet chocolate square
 * 1 cup (80 g / 2.8 oz) miniature marshmallows
 * ½ cup (40 g / 1.4 oz) chopped almonds or pecans

Procedure

 * 1) In a large saucepan, mix cocoa powder and sugar.
 * 2) Gradually stir in milk. Stir over low heat until sugar and cocoa dissolve.
 * 3) Cool to room temperature.
 * 4) Stir in vanilla, salt, and whipping cream; set aside.
 * 5) Shred chocolate with coarse side of grater.
 * 6) Stir shredded chocolate, marshmallows and almonds or pecans into cocoa mixture.
 * 7) Pour into ice cream canister.
 * 8) Freeze in ice cream maker according to manufacturer's directions.
 * 9) Stir marshmallows evenly throughout frozen mixture before serving or ripening.

title: Cookbook:Rocky Road Ice Cream


text:
Cookbook talk:Rocky Road Ice Cream

I find it odd no mention of the candy bar exists. [unsigned]

exists where? [unsigned]

 * In Australia, rocky road is known almost exclusively as a confection, with nothing to do with ice cream. I have modified the article to indicate this. I suspect "rocky road" means slightly different things in many countries, so it shouldn't be described only as an ice cream flavour. If other editors could add/clarify other regional meanings, that would help. -dmmaus 04:03, 6 April 2006 (UTC)

second only?
What is the origin of that information?

 * I believe it was from the Food Network show Unwrapped. Joyous | Talk 06:04, 31 December 2005 (UTC)

http://www.sciencenewsforkids.org/articles/20050810/Feature1.asp

this says that it's number 14 --Uccello 12:19, 4 February 2006 (UTC)

 * That seems like a more reliable source. Joyous | Talk 15:09, 4 February 2006 (UTC)

 * Here's an anecdotal source: I don't remember seeing rocky road since I was a kid. Art LaPella 02:29, 15 February 2006 (UTC)

title: Cookbook talk:Rocky Road Ice Cream


text:
Cookbook:Rocky Road Confectionery I

| Australia | Confectionery

Rocky road is a type of confectionery commonly made in Australia. It is made from chunks of marshmallow in a matrix of chocolate. Common optional ingredients include peanuts and blobs of chewy, coloured gelatine-based sweets, similar to jubes.

Ingredients

 * 12 oz chocolate morsels
 * 2 tbsp milk
 * 2 tbsp butter
 * 3 cup mini marshmallows
 * ¾ cup walnut meats, shelled and chopped
 * 1 tsp vanilla extract

Procedure

 * 1) Measure all ingredients.
 * 2) Butter an 8x8x2-inch square pan. Reserve.
 * 3) Place chocolate morsels, milk and butter into a heavy-bottomed pot. Set heat control dial at 350°F (175°C).
 * 4) Begin stirring immediately. Stir constantly until chocolate is melted and milk and butter are incorporated. Stir in remaining ingredients.
 * 5) Spread the mixture into the prepared pan.
 * 6) Refrigerate until firm, about 2 hours.

Note, tips, and variations

 * For easy clean-up, fill pot half full with water, bring to a rolling boil and then rinse.

title: Cookbook:Rocky Road Confectionery I


text:
Radiation Oncology/NSCLC/Screening

Screening

 * National Lung Screening Trial (2002-2004)
 * 2011 PMID 21714641 Full Text -- "Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening" (NEJM. 2011 Aug 4;365(5):395-409.)
 * Randomized. 53,454 persons, between 55 and 74 year of age, at high risk for lung cancer, randomly assigned to undergo three annual screenings with either low-dose CT or single-view posteroanterior chest radiography.
 * Outcome: Rate of positive screening tests: 24.2% (low-dose CT) vs. 6.9% (radiography); False positive: 96.4% vs. 94.5%; Diagnosis: 645 cases per 100,000 person-years vs. 572 per 100,000 person-years (rate ratio 1.13, 95%CI: 1.03 to 1.23); 20.0% (SS) relative reduction in mortality from lung cancer with low-dose CT screening.
 * Conclusion: Screening with the use of low-dose CT reduces mortality from lung cancer.
 * 2013 - Incidence -- PMID 24004119 -- "Results of the two incidence screenings in the National Lung Screening Trial." (Aberle DR, N Engl J Med. 2013 Sep 5;369(10):920-31.)
 * 2013 - Initial LDCT -- PMID 23697514 -- "Results of initial low-dose computed tomographic screening for lung cancer." (National Lung Screening Trial Research Team, N Engl J Med. 2013 May 23;368(21):1980-91.)
 * Positive screening test: LDCT 27% vs X-ray 9%; lung cancer diagnosis 1.1% vs 0.7%. Sensitivity and specificity LDCT 94% and 73% vs x-ray 73% and 91%
 * Conclusion: Initial screening result suggest reduction in mortality is achievable

 * Multi-Institutional, 2007 PMID 17341709 -- "Computed tomography screening and lung cancer outcomes." (Bach PB, JAMA. 2007 Mar 7;297(9):953-61.)
 * Retrospective. 3246 asymptomatic current or former smokers, annual CT screening, began in 1998. 3 institutions (Milan, Mayo, Moffitt)
 * Outcome: Diagnosis: 144 patients vs. 44 expected (RR 3.2, SS); lung resection 109 vs. expected 11 (RR 10.0, SS); advanced cases 42 vs. expected 33 (NS); deaths 38 vs. expected 39 (NS)
 * Conclusion: Screening increases rate of diagnosis and treatment, but may not reduce death from lung cancer
 * NY Times commentary, -- "How Two Studies on Cancer Screening Led to Two Results" (Welch GH, NY Times, March 13, 2007). Interpretation of these two trials. Significant controversy over this point JCO Comment

 * The International Early Lung Cancer Action Program (I-ELCAP) (1993-2005) - PMID 17065637 — "Survival of Patients with Stage I Lung Cancer Detected on CT Screening." Henschke CI et al. NEJM. 2006 Oct 26;355(17):1763-1771.
 * 31,567 pts. Screening annually using low-dose CT.
 * 484 lung cancers detected. 85% had Stage I. Of those Stage I pts, 10-year survival rate was 88% (92% for those who underwent surgical resection).
 * Conclusion: Annual CT screening can detect lung cancer that is curable.
 * Comment: Interpretation of survival data only in those screened positive. Concern about lead-time and length bias, since those patients diagnosed earlier may live longer (longer survival) but have same death rate nonetheless. Not clear who should be screened.

 * Dutch Belgian Randomised Lung Cancer Screening Trial (NELSON) (2002 - Ongoing) Registry
 * Randomised trial comparing spiral CT screening vs. observation in high risk individuals for decreasing disease specific mortality.
 * Results expected 2011

Work-Up of Pulmonary Nodules

 * Mass General Hospital, 2007 PMID 17544146 -- "Evaluating pulmonary nodules." (Miller JC, J Am Coll Radiol. 2007 Jun;4(6):422-6.)
 * Review. Algorithm described:
 * Compare current study with old study (CXR or CT). If growth, biopsy
 * If no old study, do CT. If benign calcification or fat, no action
 * If nodule on CT:
 * If immunocompromised or fever, consider short (4-6 week) follow up or biopsy
 * If history of malignancy, consider follow-up CT (3, 6, 12 months)
 * Otherwise, look at size:
 * If <=4mm, repeat CT (timing depends on age). If growth, biopsy
 * If 4-8mm, repeat CT (timing depends on age). If growth, biopsy
 * If >8mm, biopsy or PET

 * Indiana University, 2006 PMID 16567482 -- "The solitary pulmonary nodule." (Winer-Muram HT, Radiology. 2006 Apr;239(1):34-49.)
 * Review. Solitary pulmonary nodule defined as round/oval opacity <3cm diameter, surrounded by pulmonary parenchyma, not associated with lymphadenopathy, atelectasis, or pneumonia
 * Most lesions: granulomas, hamartomas, or lung cancer
 * Size : nodules approaching 3cm likely malignant, nodules <1cm likely benign
 * Location : RUL most common location of cancer. 70% of lung CA in upper lobes
 * Calcification : typically benign, unless history of bone malignancy
 * Fat : typically benign, unless history of renal cell or liposarcoma
 * Imaging features : consider attenuation, air bronchograms, margin, and cavitation; however, significant overlap in features
 * Growth rate : If no change over 2 years, can consider benign
 * PET : Best test to determine malignancy in lesions >1cm

title: Radiation Oncology/NSCLC/Screening


text:
Cookbook:Trifle

 * Desserts

Trifle, also commonly known as sherry trifle, is a traditional layered dessert in many countries. It can be prepared with or without alcohol, and the nonalcoholic version is popular with children.

Ingredients

 * 1 swiss roll or similar sponge cake
 * 50–100 ml dry sherry
 * 1 packet/sachet fruit-flavoured jelly (can be found under the brand names "Quick-Jel" or "Jell-O")
 * 1 tin of peach segments
 * Custard
 * Whipped double cream
 * Hundreds and thousands, sprinkles, or other sweet topping (optional)

Procedure

 * 1) Slice the Swiss roll approximately ¾-inch (2 cm) thick, and line the base of a Pyrex casserole dish with it.
 * 2) Pour sherry over the swiss roll.
 * 3) Drain the peaches, keeping the juice/syrup aside and then arrange the peaches over the swiss roll.
 * 4) Prepare the jelly as per the instructions, you may wish to use the syrup from the peaches for this. Pour the jelly into the casserole dish and allow to set in the fridge.
 * 5) Make the custard, again as per the instructions (use fresh or powdered as opposed to canned). Allow this to cool to lukewarm, and pour into the casserole. Allow this to set in the fridge.
 * 6) Whip the cream for the top of the trifle and spread it over the custard. Garnish with hundreds and thousands, sprinkles, or other cake decorations.
 * 7) Serve!

title: Cookbook:Trifle


text:
Microtechnology/Introduction

=Introduction= Without microchips you would not be reading this page... Microtechnology and microfabrication is a fundamental prerequisite for modern life.

This wikibook can hopefully become an opensource handbook in microfabrication. With the possibility to spawn subchapters, it should be possible to make detailed discussions of the various fabrication techniques and the processing details.

The devil is in the detail, and most people doing processing seem to have the same few lists that have been made on etch rates etc. Here, in the wiki system, users should be able to contribute and expand the readily available knowledge.

Hope you will contribute!! Things can always be changed, so its better to add things and comments to the book than just reading it!! Don't be afraid to participate :-)

Micro technology involves changing things in the scale of one micro metre, thats 0.000001 m or (10-6 m)

=A Perspective on Microtechnology=

=Applications of Microtechnology=

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Introduction


text:
Microtechnology/Overviews

= Overviews =

= Internet Resources = See also
 * This wikibook links extensively to wikipedia, but also to many valuable external resources.
 * Integrated circuit
 * Microelectronics
 * Sensors
 * Actuators
 * Transducers
 * Microfluidics

= Books =

Books about microfabrication
 * "Fundamentals of Microfabrication" (2nd ed, 2002) by M. Madou - highly recommended!
 * "Introduction to Microfabrication" (2004) by S. Franssila

= Journals = Overview of the microtechnology related journals and their impact factors (Aug. 2006 values)

= Software =

Layout Editor

 * L-Edit
 * LinkCAD
 * CleWin

MEMS Simulation

 * Coventor
 * Intellisuite

Optical Simulations

 * Olympios

= Microfabrication Products & Companies = Where to buy raw materials, wafers etc, and where to get the fabrication done is you cannot readily access cleanroom facilities.

Foundry services

 * Danchip- cleanroom access for both industry and universities
 * Freescale
 * Honeywell MEMS Foundry Services
 * X-fab
 * Micrel's Wafer Fab Division
 * ISSYS
 * Micralyne MEMS Foundry

Silicon on insulator (SOI) wafers

 * Icemostech ; UK; [sales@Icemostech.com]; Device layer +/- 0.5 µm
 * University wafers ; USA; Chris Baker [@universitywafer.com]; All kinds of wafers, possibility of small quantities
 * Soitec ; France; Sabrina Grosdidier [sabrina.grosdidier@soitec.fr]; High quality SOI, device layer +/- 5 nm
 * MEMC USA Marco Maffe [mmaffe@memc.it]; Device layer +/- 0.5 µm
 * Ultrasil ; USA; Thomas J. Gentemann [ultrasiltg@aol.com]; Device layer +/- 0,5 µm, next day shipment of wafers from online inventory
 * Okmetic Oyj ; Finland; Veli-Pekka Virtanen [veli-pekka.virtanen@okmetic.com]; Device layer +/- 0.5 µm
 * IBIS ; USA; High quality SOI; Device layer +/- 5 nm

= Microtechnology Products =
 * Intel

= A Microtechnology Timeline =
 * The first transistor
 * The first microchip
 * The first microprocessor
 * 1965 Moores Law
 * The roadmap
 * The first PCR lab-on-a-chip system
 * The first point-of-care lab on a chip system

= References =

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Overviews


text:
Microtechnology/About

About the Book

=Vision= I hope that you will contribute and make this opensource handbook a useful tool for students, process specialists and all the people who might want to know more about microtechnology!

There is a great need for easily accessible tables for process parameters as well as a continuously updated resouce for teaching materials.

=How to contribute= You are most welcome to add alter and correct throughout the book!

Media
Please put images in the commons

=History= The wikibook was started by Kristian Molhave(wiki user page) 29. June 2006. A related book is the handbook on Nanotechnology.

=Authors=
 * Main editor Kristian Molhave(wiki user page)

=Support and Acknowledgements=

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/About


text:
Microtechnology/Reaching Out

=Reaching Out=

=Outreach Projects=

=Demonstration Experiments=

=Teaching Microtechnology= Course materials available on the net:

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Reaching Out


text:
Microtechnology/Materials

=Materials=

=Overview= [[Image:Electronic_structure_of_materials.jpg|thumb|400px| Overview of the electronic structure of the different fundamental classes of materials.

Atoms have discrete energy levels for each electronic state. Electronic transitions by eg. optical excitation can change the state of the atom.

Molecules can also have discrete energy levels, but the more complex structure also gives a much more complex diagram of electronic states. In addition, the molecules can rotate and vibrate which modulates the observed energy levels.

Insulators can be seen as a condensed phase of molecules with little electronic connection between neighboring molecules for conducting a current. Only when excitation is made with an energy above the several eV bandgap will conduction be possible.

Semiconductors have a more narrow bandgap and even at room temperature a few conduction electrons will be excited into the conductance band.

Doped Semiconductors have higher electrical conductance because added dopants provide conduction electrons.

Metals can be considered as ionized metal atoms in a sea of free electrons, giving a high conductivity and high reflectivity of light (as long as it is not too high in frequency) ]]

Resources with overviews of materials and their most prominent uses:
 * Semiconductor materials
 * Ioffe NSM data archive
 * overview of microfabrication materials
 * overview of microfabrication materials
 * Semiconductor materials
 * polymers

Overview table of microfabrication materials
This table should be merged with the above...

Units

 * 1 g/cm3 = 1 kg/L = 1000 kg/m3
 * g/mol = amu = Da

=Applications and Uses=
 * Microprocessors
 * Transistors
 * Lab-on-a-chip
 * MEMS

=Product Life-Cycles= Cheap and disposable point-of-care microfluidic chips require very different materials compared to high performance microprocessors.

=Environmental Considerations= The environmental footprint of microfabriaction is not discussed very often. If anyone has knowledge about this I hope they will contribute!!

=Wafers and Substrates= Overview of wafer types, flats, cleaving planes etc.

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Materials


text:
Microtechnology/Semiconductors

=Semiconductors=

Physical Semiconductor Properties Overview Table

 * D = Diamond
 * W = Wurzite
 * Z = Zincblende
 * R = Rock Salt
 * I = Indirect
 * D = Direct
 * At ~ 2K

Some data from

Electronic Semiconductor Properties Overview Table

 * D = Diamond
 * W = Wurzite
 * Z = Zincblende
 * R = Rock Salt
 * I = Indirect
 * D = Direct
 * At ~ 2K

Some data from

=Silicon=

The traditional material for microfabrication is silicon and a wealth of processes have been developed to work with silicon wafers.

There are several different silicon crystal orientations as well as polycrystalline silicon (often called polysilicon) to choose between, and these orientations all have their own material parameters.

The Young’s modulus, Poisson’s ratio, and shear modulus are transversely and vertically isotropic for Si111 whereas these vary significantly for Si100 and Si110 .

Youngs modulus for polysilicon has values within that of crystalline silicon , which indicates that it is not affected by the grain boundaries, but is highly dependent on crystal orientation as well as the intrinsic stress.

Bulk shear modulus (which governs torsional motion) varies minimally on silicon (111), with respect to crystallographic directions, as compared to silicon (100) and (110).

It should be kept in mind that the values of Young’s modulus for microstructures are very much dependent on the size of the structure

Silicon is a nonlinear material, where the material parameters such as thermal coefficient of expansion, conductivity, and piezoresistivity  all depend on the temperature. Care must be taken when modelling the behaviour devices with a wide temperature variation.

Silicon Material Properties Overview Table

 * Extensive properties listing on with "Resistivity & Mobility Calculator for Silicon Substrates"

This table indicates that Si 111 is an attractive material compared to other Si crystal orientations when only considering the mechanical properties, because it is providing a rigid structure by the high Young’s modulus, low Poisson’s ratio, high shear modulus and also the simplest because it is transversely and vertically isotropic.

=Polycrystalline Silicon=

=IV Semiconductors= Of the IV group elements C,Si,Ge,Sn,Pb; Si and Ge are considered semiconductors although graphite,a allotropic form of carbon is conducting but its conductivity is too high than the standard semiconductors.So,it is like the metal.

=III-V Semiconductors=

Units
 * 1 N = 10^5 dyn
 * 1 GPa= 10^9 N /m2= 10^9+5dyn/m2= 10^9+5-4 dyn cm-2=10^10 dyn/cm2
 * 1 g/cm3 = 1 kg/L = 1000 kg/m3

=II-VI Semiconductors=

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Semiconductors


text:
Microtechnology/Insulators

=Insulators=

Polymers

 * tables of properties of polymers

=Silicon Dioxide= Silicon Dioxide

=Silicon Nitride= Silicon Nitride

=PMMA= PMMA

=PDMS= PDMS

=SU8= SU8

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Insulators


text:
Microtechnology/Conductors

=Conductors=

=Noble Metals=
 * Au
 * Pt
 * Ag
 * Cu
 * Ni

The values in the table have not been proof read yet!!

=Alloys=
 * TiW

=Silicides=
 * AuSi
 * TiSi

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Conductors


text:
Microtechnology/Additive Processes

=Additive Processes= Processes where material is added to the wafer.

=Overview=

=Oxidation=

Oxidation in microtechnology refers most often to the oxidation of silicon. A layer of silicon dioxide created on the surface of a silicon wafer can be easily patterned. An SiO2 layer can be created by thermal oxidation or by deposition.

=Chemical Vapor Deposition (CVD)=
 * Chemical vapor deposition and plasma enhanced CVD

=Physical Vapor Deposition (PVD)=
 * Physical vapor deposition (PVD)

Sputter Deposition

 * sputtering
 * Thin-film deposition

Electron Beam Evaporation Coating

 * Electron Beam Evaporation Coating

=Epitaxial Growth=
 * Metal Organic Vapor Phase Epitaxy (MOVPE)
 * Molecular beam epitaxy (MBE) using solid sources and Chemical beam epitaxy (CBE) using gasseuos sources.
 * Epitaxy in general.
 * Atomic layer epitaxy where only a few monolayers are deposited and bond to chemisorption sites on the surface.

=Electrochemical Methods=

Electroplating

 * Electroplating
 * list of standard reaction potentials standard reduction potentials

Electroless depositions

 * Electroless nickel plating
 * Electrochemical deposition of metals onto silicon
 * Y. Okinaka, in Electroless Plating: Fundamentals and Applications, edited by Glenn O. Mallory and Juan B. Hajdu, Chapter 15, American Electroplaters and Surface Finishers Society (1990).

=Spinning= Photo and electron beam resists as well as many other polymers are often coated on wafers by spinning a volatile solution of the compound onto the wafer.

=Surface Functionalization=
 * Self-assembled monolayers (SAM)
 * Hydrophobe and Hydrophile surface layers to control wetting.

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Additive Processes


text:
Microtechnology/Etching Processes

=Etchants=

Resources
Wikipedia
 * Wet etching
 * Chemical etching

=Wet Etch Overview Table=

References:
 * table of etchants on http://grover.mirc.gatech.edu/processing/Etchants.pdf
 * table of etchants on http://www.siliconfareast.com/etch_recipes.htm
 * See also the two papers 'Etch Rates for Micromachining Processing' Part I and II in JOURNAL OF MICROELECTROMECHANICAL SYSTEMS by Kirt R. Wiliams et al.
 * Extensive table with etch rates on http://www.eng.utah.edu/~gale/mems/etch%20rates.pdf

=Wet Etch Compatibility Chart=

=Capillary Effects= The surface tension of a wet etch solution can often make problems with movable parts in microchips and droplet formations that leave residues.

Avoiding capillary effects

 * Use dry/gas etching instead of wet (eg. HF vapor instead of HF solutions)
 * Use critical point drying
 * Quickly take from wet etchant into a water rinse bath for a thorough rinse and then quickly into an ethanol bath and then dry - the low surface tension of ethanol reduces capillary effects when drying.
 * use silicon structures with an oxide sacrificial layer - the very hydrophobic hydrogen terminated silicon after a HF wet etch will avoid capillary effects.

=Silicon KOH Etch= Potassium hydroxide (KOH) is an anisotropic wet etch that preferentially etches the 100 planes of Si and almost doesn't attack the 111 planes. This leads to a V shaped pyramidal holes in Si 100 from square openings in the etch mask, with side edges at a 54.7deg angle from the surface. The etch rate does not depend on As, P, Sb dopants, but too high B doping will reduce the etchrate in the 110 direction. The etchrate in the 100 and 110 direction can be varied by adding isopropanol to the solution.

Overall reaction: Si + 2OH- + 4H2O -> Si(OH)2++ + 2H2 + 4OH-

KOH% determination: KOH (%) = KOH dry mass(g) / solvents(ml)

Recipe for a typical 30% KOH/Isopropanol etch solution:
 * 70g KOH pellets dissolved in 190mL DI water (use heat and/or ultrasound to dissolve quickly)
 * Add 40mL Isopropanol
 * The etch rate for should be about 1 micron/minute at 80°C

KOH etch masks can be made from silicon nitride or silicon oxide (though SiO2 is slowly etched by KOH)

See also
 * http://www.virginiasemi.com/pdf/siliconetchingandcleaning.pdf
 * 'Review: The effect of alcohol additives on etching characteristics in KOH solutions' Sensors and Actuators A 101 (2002) 255–261 by Irena Zubel

=Silicon Oxide Etch (HF, BHF, BOE)= NB: HF is very dangerous, it diffuses quicker than anything you can add to try and reduce the damage, so the key is NOT to get in touch with it in the first place. It attacks the calcium in your bones, the nerves, and the blood vessels - and importantly, it does not burn like other acids!! Wear lab coats, eye protection and 6h gloves, and work in a closed fume hood.

Fundamental reaction SiO2 + 6HF -> H2SiF6+ 2H2O

Etchants:
 * HF or Hydrofluoric acid is a highly corrosive and toxic solution of hydrogen fluoride in water.
 * Buffered Hydrofluoric Etch (BHF) or Buffered Oxide Etch (BOE) is a mixture of ammonium fluoride and hydrofluoric acid with a more controlled etch rate of silicon oxide.
 * ammonium fluoride containing etches give silicon surfaces with an atomically smoother surface than HF, ammonium fluoride solutions can also be used to make atomically flat surfaces. See Appl. Phys. Lett. vol 56 p. 656 1990 by Higashi.

An oxide etch is often used to remove the impurity containing native oxide layer of wafers before contamination sensitive processes. BOE has a more controllable oxide etch rate than HF (the pH is stabilized by the buffer) but also etches Si slowly and the higher pH in BOE can cause metal precipitation, so for clean processes or thin underlying Si layers a HF etch is preferable.

 * 49% HF is used for fast removal of oxide
 * BOE gives a slower removal of oxide, but can extend the lifetime of a photoresist mask. Etch rate typically 1000-2500 Å/min.
 * Diluted HF etches - say 5% HF - is used for removal of native oxide in about 30 seconds. The surface becomes highly hydrophobic.
 * HF/HCl or HF/Glycerin mixtures can be used to make less rough surfaces when thinning oxide layers
 * HF mixed with isopropanol can be used to increase the wetting properties of the solution to better etch into narrow pores.

Etch rates vary depending on on oxide quality (eg. wether its wet furnace grown or PECVD)

Recipe for Buffered Oxide Etch or Buffered Hydrofluoric Etch
 * Prepare the 40% NH4F solution, eg 40g NH4F in 60mL water.
 * 6 parts 40% NH4F and 1 part 49% HF - HF etches glass so use plastic beakers! Add HF into NH4F instead of NH4F into HF.

Recipe for BHF/HCl etch for smooth oxide Etch rate about 1 micron/min at room temperature.
 * add 5mL Buffered Oxide etch as above to 85mL water
 * Add 10mL conc. HCl

=Silicon Nitride Etch= Typical etch rates
 * Standard etch in H3PO4 100Å/min at 180°C, 55Å/min at 165°C. Use a short BHF dip first to remove oxynitride layer.
 * 10% HF 5000 Å/min
 * 1% HF 600 Å/min
 * BHF (7:1) 5-20 Å/min

=Metal Etches=
 * table of etchants on http://grover.mirc.gatech.edu/processing/Etchants.pdf
 * See also the two papers 'Etch Rates for Micromachining Processing' Part I and II in JOURNAL OF MICROELECTROMECHANICAL SYSTEMS by Kirt R. Wiliams et al; Volume 5 Number 4 December 1996 and Volume 12 Number 6, December 2003. DOI: 10.1109/84.546406 & DOI: 10.1109/JMEMS.2003.820936
 * Table with etch rates from Kirt R. Wiliams et al. http://www.eng.utah.edu/~gale/mems/etch%20rates.pdf

=Cleaning Methods= There are several standard cleaning procedures. Some use a wealth of dangerous and highly corrosive chemicals. Don't underestimate the power of keeping things clean, and also simple soap rinses before starting on the more dangerous processes will probably increase the quality of the result.

Rinsing
In cleanrooms you often see people rinsing by submerging a wafer into a bath with running water. This has the advantage that the wafers do not dry out and eventually whatever should be washed away will be removed.

But think of how you can get tea leaves out of a tea pot: If you put the pot under running water, it will probably never ever really get completely free from leaves, whereas if you pour as much out as possible, add a little water, empty again and repeat a couple of times, your pot is completely clean with almost no use of water. The math is simple. If you add 1/10 of water pr minute in a large bath you dilution will take place very slowly compared to adding a small amount of water that maybe is gives a 50/50 dilution in one go and thereby rapidly decrease the fraction of original contaminant considerably.

Flushing your wafers with a jet of water probably orders of magnitude more efficient and faster at rinsing than submerging in a bath...

Ultrasound
Ultrasound baths work by standing waves of high frequency sound that at the wave anti-nodes create so high pressure variations that water vapor bubbles form and implode during the sounds pressure cycle. The bubble implosion creates shock waves that knock any loose material off surfaces and also can initiate chemical reactions or cause pitting in soft materials and damage smaller MEMS structures.

Soap
Don't underestimate the power of ordinary soap or more harsh treatments with surfactants such as Triton-X. Especially together with ultrasound.

RCA
A standard wafer cleaning method developed by the RCA corp. It is made from 2 baths:
 * RCA1 is a H2O:NH4OH:H2O2 cleaning of organic residues
 * RCA2 is a H2O:HCl:H2O2 etch of metal impurities.

RCA cleaning is often used before furnace processes.

See also
 * http://www.virginiasemi.com/pdf/siliconetchingandcleaning.pdf

Piranha
Piranha solutions are often made from sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). But basic solutions and other recipes are also named piranha. The solution is very corrosive. Use fume hood, lab coat, eye protection and nitrile/6H gloves. To effectively demonstrate to people how dangerous it is, try putting a small droplet on a piece of paper and it instantly is burning black with a hissing sound.

 * Acid Piranha (Caro's acid, Sulfuric Peroxide) - for 10mL Piranha, pour 7mL 95% H2SO4 into 3mL 30% H2O2 -use glass beakers. The mixture heats on mixing to about 80°C

This is a piranha etch with Ammoniumperoxydisulfate. Mix 1L 95% H2SO4 at 80°C with a table spoon of Ammoniumpersulfate. The solution will start to bubble indicating that it is ready. It can be reused several times (add another spoon of Ammoniumperoxydisulfate every time) until it does not bubble any longer and must be replaced.
 * Peroxydisulfuric etch (also nicknamed 7-up since it bubbles upon heating to 80°C).

 * Base Piranha is a 3:1 mixture of ammonium hydroxide (NH4OH) with hydrogen peroxide.

Piranha solutions etches organic compounds vigorously. It can form explosive compounds if mixed with organic solvents, so be careful and do not work near eg. acetone, ethanol or isopropanol with piranha.

The exothermic heat of mixing can bring solution temperatures up to 120°C and can lead to violent boiling, or even splashing of the extremely acidic solution. Explosions may occur if the peroxide solution concentration is more than 50%. A 30% peroxide in water solution is more reasonable.

Too thick organic contamination can harden up in piranha, so a degrease clean is often made before piranha cleaning.

For instance a sequential cleaning as follows is often used for substrates used for epitaxial growth:
 * 2min sonication in Tri-chlor ethylene
 * 2min sonication in acetone
 * 2min sonication in ethanol
 * 2min sonication in millipore water (MPW)
 * then rinse in MPW 3 times.
 * Piranha etch 6 min.
 * Rinse in MPW 3 times.
 * Dehydration bake 200-250°C for 30 min.

=Dry Etching Overview= Dry etching on Wikipedia

=Reactive Ion Etching (RIE, DRIE, ASE)=

Advanced Silicon Etch (ASE) / Deep Reactive Ion Etch (DRIE)

 * DRIE on Wikipedia

=Dry Cleaning Methods (Plasma, Ozone)=

Plasma Ashing
Plasma Ashing on Wikipedia

Ozone Cleaning
Ozone cleaning on Wikipedia

Sputtering
Sputtering on Wikipedia

=Laser Ablation=
 * Carbon dioxide laser cutting of sub-millimeter structures in plastics
 * Eximer laser ablation of materials
 * Solid state laser ablation of materials

=Gas Etches=
 * Hydro fluoric gas etching of oxide to avoid collapse of silicon MEMS structures that would happen during drying if etched in aqueous fluoride etchants. See eg. http://www.imec.be/wwwinter/microsystems/SPIEpaper.pdf
 * Xenon Difluoride (XeF2) anisotropic (non-directional) dry-etching of Ge for similar reasons as above.
 * Laser activated chlorine gas etch of nanoscale patterns

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Etching Processes


text:
Microtechnology/Lithography

=Lithography=

 * SPIE Handbook
 * Intro to lithography

=Ultra Violet Lithography (UVL)=
 * Photolithography
 * Photoresist

Masks for UVL
Various types of masks are in use for UVL:
 * Chrome-on glass maks for structures down to micron-resolution
 * Acetate masks for structures with minimum dimensions of tens of microns

Negative UVL resists

 * PMMA
 * SU-8

Positive UVL resists
=Electron Beam Lithography (EBL)= Electron beam lithography offers linewidths down to the few nm range, much smaller than what can bea achieved by optical lithography. One drawback is that the pattern writing is a serial process and hence very time consuming for larger structures.

Resources on the net
 * SPIE Handbook of Microlithography, Micromachining and Microfabrication has an online chapter on EBL

What determines the EBL resolution

 * Beam diameter
 * Resist sensitivity
 * development method
 * Proximity effect
 * Resist thickness

Negative E-beam resists
negative e-beam resists will remain in the irradiated areas after development.
 * Electron beam induced deposition
 * PMMA
 * SU-8

Positive E-beam resists
Positive e-beam resists will be removed in the electron irradiation areas upon development. PMMA Typical PMMA process
 * 300nm PMMA think film made by spinning 950k PMMA 5% in anisole at 5000rpm for 30sec (avoid bubbles in the resist when placing it on the wafer, use about 3ml for a 4" wafer).
 * drying 180C Hot plate for 2 min or oven bake for at least 2h at 180 C. Oven takes longer than hot plate as convection heat trasnfer is slower than contact transfer.
 * Electrob beam lithography. Dosage depends on pattern density and acceleration voltage.
 * Developing in MIBK:IPA (1:3) for 60s and rinse in IPA for 30s.
 * Post bake to improve etch resistance. 30 min at 110C
 * 5 mBar Oxygen plasma in faraday cage for 20 sec to remove residual resist.
 * For instance metal evaporation to form metal structures, followed by liftoff 5 min in hot remover s-1165 and acetone in several fresh baths to remove liftoff fragments.

 * ZEP

=Resist Coatings=
 * Spinning
 * Electrochemical coating
 * Spray coating (Spray coaters are made by eg. EVG)
 * Drop casting
 * Self assembled monolayers

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Lithography


text:
Microtechnology/Additional Methods

Additional Methods
Apart from additiev and etching processes, there is also a range of processes to alter the materials properties and to characterize them.

Rapid Thermal Anneal (RTA)

 * Rapid thermal anneal (RTA)

Wafer Bonding
Wafer bonding Wafer bond characterization
 * Direct bonding
 * Plasma activated bonding
 * Anodic bonding
 * Eutectic bonding
 * Glass frit bonding
 * Adhesive bonding
 * Thermocompression bonding
 * Reactive bonding

Doping

 * Dopant

Ion Implantation

 * Ion Implantation

Interconnections

 * Wire bonding
 * Flip chip bonding
 * Wedge bonding
 * Using ZIF sockets

Encapsulation

 * Silicone oil
 * Spray-on polymers

Glues

 * Epo-tek H77 is a common packaging two-component UHV compatible epoxy glue.
 * Fortafix makes a high temperature glue that should work up to around 1000 C called Rocksett.
 * Vitcas Refractories manufacturer of high temperature glue/adhesives for industrial and domestic use up to 1700 C

Ellipsometry
Ellipsometers are used to measure thin film thicknesses by their optical properties (refractive index and reflectivity/absorbance).

4 Point Measurements
The four-point probe technique can be used to measure the conductivity of thin films. For improved measurements micro four-point probes can be used. Capres has an application note about micro four-point probes.

Atomic Force Microscopy
The Atomic force microscope (AFM) is mainly used to measure the topography of a surface, such as the roughness.

Scanning Electron Microscopy
JEOL has a good guide to SEM image interpretation

Optical Microscopy
Theres a good introduction to optical microscopy from Zeiss.

Vacuum Equipment

 * mass flow controllers (MFC) Gas conversion factors and formulas for calculating them

title: Microtechnology/Additional Methods


text:
Microtechnology/Microelectronics

=Microelectronics=

See the Wikibook Semiconductors on electronic devices

=An Ohmic Resistor=

=The Diode=

=The Transistor=

=CMOS= complementary metal oxide semiconductor

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Microelectronics


text:
Microtechnology/Photonics

=Photonics=

=Waveguides=

=Photonic Band Gap Structures=

=Electro-optical Devices=

...

Mach-Zender optical modulator , also spelled the Mach-Zehnder interferometer.

...

=References=

See also notes on editing this book about how to add references Microtechnology/About.

title: Microtechnology/Photonics


text:
Microtechnology/Microelectromechanical Systems (MEMS)

=Applications= =Resonators= =Strain Gauges= =Pressure Sensors= =AFM cantilevers= =Acceleration Detectors= =Optical Beam Control= =RF MEMS=
 * Microelectromechanical Systems (MEMS)
 * RF_MEMS

= Reliability design rules =

Sandia has published a set of "reliability design rules" for MEMS devices intended to avoid failure modes experienced in early MEMS device tests. The most common failure mechanism was wear of the rubbing surfaces.

=References=

See also notes on editing this book about how to add references Microtechnology/About.


text:
Cookbook:Cheese Spread on French Bread

| Snacks

Ingredients

 * ½ tbsp Dijon mustard
 * 1 tbsp butter, room temperature
 * 2 tsp dried sage
 * ¼ cup apple juice
 * 2 cups shredded sharp cheddar cheese
 * ½ tsp pepper
 * 8 oz package cream cheese, softened
 * 1 loaf French bread, cut in small slices

Procedure

 * 1) In a large bowl, mix together mustard, butter, and sage.
 * 2) Add the apple juice, cheddar cheese, and pepper, then stir well.
 * 3) Add the cream cheese, blending well.
 * 4) Cover and refrigerate for 3 hours.
 * 5) When ready to serve, remove from refrigerator and allow to stand for ½ hour.
 * 6) Spread on bread and serve with milk.

title: Cookbook:Cheese Spread on French Bread


text:
Adventist Youth Honors Answer Book/First aid/Electric wire contact

First, do not touch a person who comes into contact with a live electric wire. If you do, the electricity will also flow through your body, and there will be two victims instead of one. Instead, if you can quickly turn off the power source, do so immediately. If it cannot be turned off quickly, try to knock the wire off with something that does not conduct electricity, such as a shoe (take it off first), a wooden broom handle, or a wooden chair.

Once the victim has been separated from the electric power source, check for breathing. If the victim is not breathing, begin artificial respiration (mouth-to-mouth).

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text:
Cookbook:Snacks

Snacks are small tidbits, usually eaten with the fingers, though occasionally with utensils. They may require utensils to prepare. They may even be nutritionally beneficial, but this is not a requirement.

Snacks

 * Cheese Spread on French Bread
 * Party Mix
 * Toast
 * Microwave Chocolate Cake
 * Popcorn
 * Date bar
 * Cookies and milk
 * Crisps
 * Vegetable sticks and cream cheese
 * Cereal and milk

title: Cookbook:Snacks


text:
Adventist Youth Honors Answer Book/First aid/Litter carry

When transporting an injured person, always see that the litter is carried feet forward no matter what the injuries are. This will enable the rear bearer to observe the victim for any respiratory obstruction or stoppage of breathing.

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text: Nets, Webs and the Information Infrastructure/Notes