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Circuit Idea/Why Circuit Ideas are Hidden

<<< contents - hide ideas - kill ideas - formulas - page stage >>>

Why Circuit Ideas are Hidden

(Why Inventors, Authors, Lecturers, Professionals and Producers Frequently Hide Circuit Ideas)

Circuit ideas are frequently hidden
Electronic devices are based on brilliant circuit ideas that are conceived once in beautiful minds by lots of imagination, intuition and emotions. However, time mercilessly covers up these pearls of human thought and we have to dig for long in the garbage of mediocrity to uncover them...

Fortunately, in many cases the fundamental ideas behind circuits are clear and simple; so, we may derive them routinely relying on our experience. But for no apparent reason some circuit ideas are still thoroughly disguised. As a result, there are lots of circuits that never get explained in classical electronics sources.

Why are basic circuit ideas hidden? Why do we have to find answers ourselves to all these reasonable questions: "What is the idea behind the circuit? Where has it come from? How has the circuit idea been evolving through years?" Let's try to reveal the mystery of this phenomenon.

Looking for an answer in original sources
At first glance it would seem sufficient to read original (primary) sources to find out the ideas behind circuits. But there are obstacles that prevent us from revealing ideas in such a way.

Explaining abilities
Not every circuit originator (inventor, designer, scientist, etc.) has a gift for explaining and presenting circuit ideas. To invent a novel circuit structure does not exactly mean to present the idea behind it in the best way (the art of creation does not always involve the art of performance). In many cases, even if professionals want to explain their own circuit ideas in the best way, they are not successful. A routine example: as a rule, poets and composers do not perform their works in the best way.

Lacking of explaining abilities is typical for hobbyists that prefer rather to do something than to explain in the best way how it operates. Authors of articles published in hobby magazines, books and web resources usually give ready-made circuit diagrams with concrete components and values but do not show why.

Willingness for disclosing
Not everyone who invents a circuit wants to disclose its secret for variety of reasons. Let's consider some typical examples.

Patent descriptions
Patents are classical examples of such a reluctance. Why are patent descriptions so difficult to understand for ordinary people? The reason is that inventors just do not want to make circuit ideas clear and understandable! An army of patent specialists help inventors to professionally hide their ideas. There is a contradiction in patenting: from one side, the inventor must to reveal the idea; from the other side, he/she wants to hide the idea. Actually, inventors do not want to share what they invented with people; just the contrary, they want to keep it for themselves! If we compare patenting with Wikibooks idea, we can realize how deeply selfish patenting is.

Professional publications
It seems strange, but it is true that professionals very often hide circuit ideas. The reasons are various.

Inventors usually do not like to tell how they have invented circuit solutions. Maybe, they are afraid that revealing the circuit evolution will cloud their glory; so, they would like the ordinary people to think of inventing as a heavenly gift. In many cases, the way of inventing is even more valuable than the result of inventing. In other cases, it is more useful for understanding to imagine that the circuit is invented in a different than the actual way (i.e., the logic of understanding may differ from the logic of inventing). For example, few books (especially professional publications) explain the transistor operation in an intuitive way; instead, they directly jump to the mathematical expressions instead of explaining its principle of working. However, mathematical expressions are secondary part and are helpful for increasing the efficiency of circuit, they will not tell us the operation of circuit and how the circuit is designed.

Producers of electronic components are not interested in revealing circuit ideas; instead, they are interested in advertising their wares (components, devices, etc.) For example, an EDN's article states that a low-resistive load may be cancelled by placing in parallel the same negative resistance. However, the author has not shown what the op-amp actually does to act as a negative "resistor" but he has not forgotten to show the type of the op-amp (Maxim's MAX4165 op-amp). Seeing such a concrete circuit reader has the impression that this is the only possible circuit implementation. If there are not such components as shown, reader will not be able to make the circuit; he has to wait until other manufacturers suggest their components:) Actually, the idea is extremely simple and intuitive: the op-amp "helps" the input reference voltage source by injecting the whole current needed through the load (see the picture on the right).

Design engineers scrutinize interesting and useful technical details about circuit solutions but, as a rule, they do not like to reveal circuit ideas in the introductory part of the materials. Professionals usually think that "the ones that know do not need explanations while the ones that do not know will never understand it". For example, in another EDN's article, the famous Bob Pease from National Semiconductor has shown useful tips about designing the popular circuit of transimpedance amplifier; only, he has "forgotten" first to show the general idea behind the legendary circuit. Actually, this is the same "helping idea" as above; only, here the op-amp's output is connected in series with the input source and the resistor. Thus it "helps" the input source by adding so much voltage in the circuit as it loses across the resistor.

After this short "excursion" through the world of original sources we can already see the answer to the question, "Why are circuit ideas hidden?" Maybe, the main reason is that lots of actual authors actually do not like to explain circuits; they only like to create them.

Looking for an answer in second-hand sources
In circuitry, like in most areas of life, a few gifted people invent novel circuit solutions; then, an army of not so gifted, normal and poor people reproduces these ideas down the years. After such a reiteration valuable ideas can mutate and even vanish the same way that a sentence generally changes a little from person to person during a telephone game. It is even possible that the writer or teacher that present the circuit actually has not understood the idea behind it; as a result, readers or students will also not understand the circuit.

Well, let's prove these assertions. Imagine we are curious people that peek into various electronics sources in the hope of revealing circuit ideas. What do you think we will see?

Textbooks. If we turn over the pages of classical electronics textbooks, in the most cases (excluding The art of Electronics and the accompanying Student Manual for The art of Electronics, we will find there formulas, definitions and formal analyses. By using these quantitative means, authors (usually university lecturers) try to explain qualitative things. Why do they do that? Maybe, in this way they add more credits to climb the professional ladder? Or, if they are vain enough, just want to rise in the esteem of students? As a result, circuit ideas remain hidden for poor students.

Books. Maybe, we will manage to find out circuit ideas in traditional electronics books? Alas! Instead, we can most frequently see there ready-made circuit solutions to be analyzed in their complete, final and perfect form. Books claiming to show the basic circuit ideas (e.g., Floyd's Fundamentals of Analog Circuits) do not show any circuit idea although they are useful for other purposes. Even books pronouncing themselves as inventive do not reveal actually any circuit idea. For example, otherwise useful for technicians book Practical Electronics for Inventors actually does not show how to invent at least one new circuit!

Magazines, conferences, dissertations... In many cases, they are exploited by poor university lecturers and scientists for the purposes of their career. In order to satisfy academic requirements, as a rule, such materials are formal, dull and vague. They serve mainly other poor people to use them, in order to write more poor materials that will serve other poor people... and again and again... Such "reputable" materials have usually many authors that cite each other thus implementing the principle "I to you, you to me". Obviously, we will not find there the truth about circuits...

Hobby books, magazines and resources. As they are intended mainly for doers than for thinkers these sources prefer to give ready-made circuits with concrete electronic components and values. This is all very well if the circuit runs successfully, but what do we do if it doesn't? How do we repair it, if we do not know how it functions?

Lecture halls. Maybe, we will find the truth about circuits in university lecture halls? Alas! We will see there how lecturers try to explain circuits skilful juggling with formal methods; they treat poor students as computers, not as human beings. This approach frequently leads students to absurdity analyzing something not really knowing what it is. Why is this manner of teaching widely used? Maybe, it is just convenient...

Educational laboratories. Then let's peek into modern laboratory; maybe, there they will show circuit ideas? However, even the most perfect instruments and simulating programs do not reveal circuit ideas, if instructors compel us to use them in a traditional way (measure Ib and Ic, calculate ß, write a report, etc.) Instruments do not have imagination, they can't show circuit idea.

Web resources. Maybe, it is our last hope to find out circuit ideas and maybe, it is our biggest disappointment... Browsing through the web we see that only the way of presentation has changed but the content is the same...

After this "excursion" through the world of the second-hand sources we can already see more answers to the question, "Why are circuit ideas hidden?" Maybe, the main reason is that lots of secondary authors actually do not like circuits. They know circuits but do not understand them. Circuitry is more a routine job than a favorite pursuit for them. They have not a vocation for explaining circuits; so they can work with the same success in other completely different areas.

Conclusions
For various reasons, in the most cases great ideas behind circuits are hidden or mutated. It turns out that there is no place for revealing basic circuit ideas. No one shows what we, human beings, actually need - what basic circuit ideas are, where new circuit ideas come from and how they have been evolving through years.

Obviously, nobody can perform our work. We have to form by ourselves universal methods and skills for revealing the basic ideas behind circuits and then to enrich them continuously. In order to understand how circuits act, we have to revolve the ideas in our mind, in order to associate them with our former knowledge of life.


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Insubric/Altered nouns

The altered nouns (augmentative, diminutive, petting and pejorative) are always oxytone because of their suffixes. The suffixes are joined not to the noun, but to its stem, so deleting the desinences (like -a for feminine form) and the euphonic vowels (derivating from schwa), recuperating the vanished consonants (like r, l, d after long vowels), and receiving apophony because of the change of position of the stress (for example, oeu and o /o/, losing stress become o /u/).

Here are the most frequent masculine altering suffixes. You have to add an -a if you want to form the feminine form (for -oeu you can't). Sometimes, some feminine nouns, when altered, use the masculine form.

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

title: Insubric/Altered nouns


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User talk:Xera10

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.– Mike.lifeguard  | talk 00:59, 24 September 2007 (UTC)

Image:Hull House.jpg is a copyright violation
Please note that this image is not permitted on Wikibooks. It will be deleted in about a week. If you have questions, please ask me on my talk page, or at the staff lounge. Please be sure not to upload images that are copyright violations, or images with no license information. If you continue, you may be blocked from editing Wikibooks temporarily. – Mike.lifeguard  | talk 16:41, 23 September 2007 (UTC)
 * Image:Horace Mann.jpg is a copyright violation as well. – Mike.lifeguard  | talk 16:45, 23 September 2007 (UTC)

title: User talk:Xera10


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Muggles' Guide to Harry Potter/Magic/Doxy

Overview
A Doxy (otherwise known as Biting Fairy) is a small fairy-like creature, covered in hair with two pairs of arms and two pairs of legs. Doxies have two rows of sharp, venomous teeth.

Extended Description
Doxies are pests; Doxycide, a black liquid that effectively knocks them out, is needed to dispose of them.

Doxies are encountered in Harry Potter and the Order of the Phoenix when an infestation of them was found in the curtains of the drawing room at number twelve, Grimmauld Place. Fred and George, who had been hired to help with the spraying, secretly pocketed a large number of Doxy eggs, which were presumably used when developing Skiving Snackboxes for Weasleys' Wizard Wheezes.

In the run-up to the O.W.L. exams in that same book, one of the students, named Howard Dingle but otherwise unseen, claims to have powdered Dragon claw available for sale. Hermione, who is a Prefect, confiscates and examines it, and finds it to be dried Doxy droppings.

From a throw-away comment by Aberforth Dumbledore in Harry Potter and the Deathly Hallows, "They'd be on you like Bowtruckles on Doxy eggs," we surmise that Doxy eggs are a favoured food for Bowtruckles, when they can find them. Doxy eggs are apparently hard to find.

Analysis
Doxies are not described in the books; though Harry sees them quite close to and actually has to spray one of them that is headed for his face, the author does not go into detail as to what he sees. This description is courtesy Magical Beasts and Where to Find Them, by "Newt Scamander".


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User talk:Shannondl11

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Copyright problem with Image:Sps2.jpg

 * This appears to be your own work. Please decide how you want to license it and tag it as such. If you need help to decide, or to tag the image, please ask on my talk page, or at the staff lounge. – Mike.lifeguard  | talk 16:52, 23 September 2007 (UTC)
 * Please do the same for all your image uploads. They will be deleted in about a week unless appropriate license information is provided. – Mike.lifeguard  | talk 16:53, 23 September 2007 (UTC)

title: User talk:Shannondl11


text: Category:Book:Introduction to Astrophysics


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Automobile Repair/Nissan/Maxima (4th Generation)/Changing the oil and oil filter

Changing you oil/filter regularly is one of the most important things you can do to keep your engine running. It should be done between 3,000 miles and 7,000 miles depending on how the car is driven.

Tools/Parts needed

 * New oil filter
 * Oil filter wrench
 * A medium size adjustable wrench or a metric socket set.
 * 5 quarts of new engine oil

Procedure

 * 1) Let engine warm up, 5 minutes should be enough.
 * 2) Pull front passenger side of the car up on to a curb (or your preferred way of raising the front of the car).
 * 3) Get under the car, look for the belts on the passenger side, there will be a small tank under them with a bolt in it.
 * 4) Remove the bolt, and let all the oil come out.
 * 5) When the oil is done dripping use your oil filter wrench to remove the oil filter (it loosens by pulling the end of the wrench towards the front of the car.  Once off let it drip for a while.
 * 6) Now reinstall the engine oil plug tightly.
 * 7) Now install the new oil filter (bottom of filter rotates toward the back of the car), after the seal on the filter meets the engine tighten it one rotation with the wrench.
 * 8) Fill engine with four quarts of oil and start for a minute, shut car off and remove and clean dipstick.  Check oil level with dip stick.  If the dip stick is not giving accurate reading let the oil settle to the bottom of the engine for 5 to 10 minutes.  Add oil until the dip stick is a little below the H line on the dip stick.


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Category:Pages needing sources

This category contains pages in which someone has requested a reliable source of information be cited to verify information cited as facts, usually through uncited for an entire page or citation needed for a particular statement.

__HIDDENCAT__

title: Category:Pages needing sources


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User talk:Sandman85048

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title: User talk:Sandman85048


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XQuery/Incremental Searching

Motivation
You have a large data set and you want to use JavaScript to asynchronously communicate with a server to narrow the scope of the search as a user types.

US Zip Code Example
There are around 43,000 5 digit ZipCodes in the US. There are a number of applications to convert a zip code to a location, for example Ben Fry's Java applet written using Processing

This example uses a client-side XHTML page using Ajax to request a subset of codes from a server-side search of an XML database of Zipcodes, updating the page dynamically.

The HTML page
Generated by an XQuery although the content is static.

declare option exist:serialize "method=xhtml media-type=text/html indent=yes";

 ZIP Code to City and State using XmlHttpRequest  US Zipcode decoder  ZIP code:  e.g. 95472

Javascript
Uses XMLHttpRequest to request the subset and innerHTML to update the page.

function updateList { if (http.readyState == 4) { var divlist = document.getElementById('list'); divlist.innerHTML = http.responseText; isWorking = false; } }

function getList { if (!isWorking && http) { var zipcode = document.getElementById("zip").value; http.open("GET", "getzip.xq?zipcode=" + escape(zipcode), true); http.onreadystatechange = updateList; // this sets the call-back function to be invoked when a response from the HTTP request is returned isWorking = true; http.send(null); } }

function getHTTPObject { var xmlhttp; /*@cc_on @if (@_jscript_version >= 5) try { xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } catch (E) { xmlhttp = false; }   }  @else xmlhttp = false; @end @*/ if (!xmlhttp && typeof XMLHttpRequest != 'undefined') { try { xmlhttp = new XMLHttpRequest; xmlhttp.overrideMimeType("text/xml"); } catch (e) { xmlhttp = false; } }  return xmlhttp; }

var http = getHTTPObject; // create the HTTP Object var isWorking = false;

XQuery search
The Server-side XQuery to perform the search in the XML database and generate the XHTML. This uses the eXist full text index and the exist-specific &= operator.

let $zipcode := request:get-parameter("zipcode",) return {if (string-length($zipcode) > 1)  (: too slow :) then let $search := concat('^',$zipcode) for $zip in //Zipcode[matches(Code,$search)] return {string-join(($zip/Code,$zip/Area,$zip/State),' ')} else }

XML data file
The data was originally a CSV file, converted to XML using Excel and the XML add-in. This is a sample of the data.

  Portsmouth NH   Portsmouth NH </Zipcode> <Zipcode> <Area>Portsmouth</Area> <State>NH</State> </Zipcode> <Zipcode> <Area>Portsmouth</Area> <State>NH</State> </Zipcode> ...

Execute

title: XQuery/Incremental Searching


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Cookbook:Dabeli (Potato-stuffed Buns with Chutney)

Dabeli is an Indian dish, originally from the region Kutch in Gujarat. Dabeli is now a common street food in Mumbai. It is also called double roti or kutchi dabeli.

Filling

 * 1 tablespoon oil
 * 1 pinch of asafoetida powder
 * 2 teaspoons dabeli masala
 * 2 medium-sized potatoes, boiled and mashed
 * Salt
 * Water
 * Green chiles (optional), finely chopped
 * 2 tablespoons peanuts, roasted

Assembly

 * 5–6 ladi-pav or burger buns
 * Butter
 * 1 onion, finely chopped
 * ¼ cup sev
 * Garlic chutney (optional)
 * Tamarind date chutney

Garnish

 * Finely-chopped cilantro
 * 1 handful of pomegranate seeds (optional)
 * Roasted peanuts

Filling

 * 1) Heat oil in a pan. Add asafoetida, dabeli masala, potatoes, salt to taste, and a sprinkle of water. Mix it very well so that masala, salt and boiled potato assimilate very well.
 * 2) Mix in the green chiles if using.
 * 3) Remove potato mixture from the heat, and taste. If you want to make it more spicy, add some more dabeli masala, and mix again using your hands or a masher. Toss in the roasted peanuts and mix everything well.

Assembly

 * 1) Slice pav/bun into halves, and toast them with a little butter on a griddle.
 * 2) Apply garlic chutney to one half of the bun (inner side) and tamarind-date chutney to the other half.
 * 3) Place a portion of the potato filling in between between the bun halves.

Garnish

 * 1) Top with chopped onion, coriander, and sev.
 * 2) Press down the bun from both side, and garnish with pomegranate seeds, and roasted peanuts.
 * 3) Serve immediately, while medium-hot, with a extra dip of chutney on the plate. Fried green chillies, with a sprinkle of salt can be additionally given as an add-on.


text: User talk:Arnodenhond

title: User talk:Arnodenhond


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User talk:AdamStevenson

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.– Mike.lifeguard  | talk 00:58, 24 September 2007 (UTC)

title: User talk:AdamStevenson


text:
User talk:Chainsawriot

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.– Mike.lifeguard  | talk 02:13, 24 September 2007 (UTC)

DanielwayneR
This book doesn't have a very descriptive name. Before there are too many pages to move, you might consider using a different title - something like Biostatistics in R would be a good, descriptive title. Not many people coming to Wikibooks will be searching for a book with the title DanielwayneR. If you need help coming up with a better title, or with moving pages, please ask on my talk page, or at the staff lounge. – Mike.lifeguard  | talk 13:45, 24 September 2007 (UTC)

title: User talk:Chainsawriot


text:
User talk:24.158.217.179

 * – Mike.lifeguard  | talk 02:14, 24 September 2007 (UTC)

title: User talk:24.158.217.179


text:
Biostatistics with R

Wayne W. Daniel's Biostatistics (ISBN: 9780471456544) is a standard textbook for a lot of Biostatistics courses around the world. Similar to other books on similar topics, the examples of statistical computing given in Daniel's book haven't cover R. (Even it gives the examples in MINITAB, SAS and SPSS) As biostatistics is the trade and the statistical packages are only tools, one should believe all examples in Daniel's book can be rewritten in R. R, as a free and open source interpreter of S language, deserved some spots in Daniel's book and in the field of Biostatistics as a whole.

This wikibook is a companion to the Tenth Edition of Daniel''s book. The data sets are available for download from the Wiley Web Site. The instruction for importing these data sets into R will be introduced in chapter 2.

From Chapter 3 to Chapter 17, this companion book content exactly follows Wayne W. Daniel's book. Each chapter starts with summary for formular in Wayne W. Daniel's Biostatistics (ISBN: 9780471456544) and their expression in R programming. The sections per the chapter also follows Daniel's book content and includes Examples and Exercise in Daniel's book and direction in R programming. The sections which do not have examples and exercise will not be discussed here.

Volunteer Editor
 * This is a wiki project - an open source, free access reference book. Anyone would be welcome and encouraged to contribute anytime, anything (as long as it relates to Biostatistics with R).
 * Hanjin Deviasse Toronto,ON,Canada

Table of Content
Authors
 * 1) /A Brief Introduction To R/
 * 2) The First Step in R
 * 3) Data types and basic functions in R
 * 4) R programming for writing functions
 * 5) Basic graphics in R
 * 6) Data Import in R
 * 7) /Introduction to Biostatistics/
 * 8) Descriptive Statistics:Summary of formulas with R
 * 9) /The Ordered Array/
 * 10) /Grouped data:The frequency distribution/
 * 11) /Descriptive Statistics:Measures of Central Tendency/
 * 12) /Descriptive Statistics:Measures of Dispersion/
 * 13) Review Questions and Exercises
 * 14) Some Basic Probability Concepts:Summary of formulas with R
 * 15) /Calculating the probability of an event/
 * 16) /Bayes’ Theorem, Screening Tests Sensitivity, Specificity, and Predictive Value Positive and Negative/
 * 17) Review Questions and Exercises
 * 18) Probability Distributions:Summary of formulas with R
 * 19) Probability Distributions of Discrete Variables
 * 20) The Binomial Distribution
 * 21) The Poisson Distribution
 * 22) Continuous Probability Distributions
 * 23) The Normal Distributions
 * 24) Normal Distribution Applications
 * 25) Review Questions and Exercises
 * 26) Some Important Sampling Distributions:Summary of formulas with R
 * 27) Distribution of the Sample Mean
 * 28) Distribution of the Difference Between Two Sample Means
 * 29) Distribution of the Sample Proportion
 * 30) Distribution of the Difference Between Two Sample Proportions
 * 31) Review Questions and Exercises
 * 32) Estimation:Summary of formulas with R
 * 33) Confidence Interval for a Population Mean
 * 34) The t Distribution
 * 35) Confidence Interval for the Difference Between Two Population Means
 * 36) Confidence Interval for a Population Proportion
 * 37) Confidence Interval for the Difference Between Two Population Proportions
 * 38) Determination of Sample Size for Estimating Means
 * 39) Determination of Sample Size for Estimating Proportions
 * 40) Confidence Interval for the Variance of a Normally Distributed Population
 * 41) Confidence Interval for the Ratio of the Variances of Two Normally Distributed Populations
 * 42) Review Questions and Exercises
 * 43) Hypothesis Testing:Summary of formulas with R
 * 44) Hypothesis Testing: A Single Population Mean
 * 45) Hypothesis Testing: The Difference Between Two Population Means
 * 46) Paired Comparisons
 * 47) Hypothesis Testing: A Single Population Proportion
 * 48) Hypothesis Testing: The Difference Between Two Population Proportions
 * 49) Hypothesis Testing: A Single Population Variance
 * 50) Hypothesis Testing: The Ratio of Two Population Variances
 * 51) The Type II Error and the Power of a Test
 * 52) Determining Sample Size to Control Type II Errors
 * 53) Review Questions and Exercises
 * 54) Analysis of Variance:Summary of formulas with R
 * 55) The Completely Randomized Design
 * 56) The Randomized Complete Block Design
 * 57) The Repeated Measures Design
 * 58) The Factorial Experiment
 * 59) Review Questions and Exercises
 * 60) Simple Linear Regression and Correlation:Summary for formula with R
 * 61) The Regression Model
 * 62) The Sample Regression Equation
 * 63) Evaluating the Regression Equation
 * 64) Using the Regression Equation
 * 65) The Correlation Model
 * 66) The Correlation Coefficient
 * 67) Some Precautions
 * 68) Review Questions and Exercises
 * 69) Multiple Regression and Correlation:Summary of formulas with R
 * 70) The Multiple Linear Regression Model
 * 71) Obtaining the Multiple Regression Equation
 * 72) Evaluating the Multiple Regression Equation
 * 73) Using the Multiple Regression Equation
 * 74) The Multiple Correlation Model
 * 75) Review Questions and Exercises
 * 76) Regression Analysis: Some Additional Techniques:Summary of formulas with R
 * 77) Qualitative Independent Variables
 * 78) Variable Selection Procedures
 * 79) Logistic Regression
 * 80) Review Questions and Exercises
 * 81) The Chi-Square Distribution and the Analysis of Frequencies:Summary of formulas with R
 * 82) The Mathematical Properties of the Chi-Square Distribution
 * 83) Tests of Goodness-of-Fit
 * 84) Tests of Independence
 * 85) Tests of Homogeneity
 * 86) The Fisher Exact Test
 * 87) Relative Risk, Odds Ratio, and the Mantel–Haenszel Statistic
 * 88) Review Questions and Exercises
 * 89) Nonparametric and Distribution-Free Statistics:Summary of formulas with R
 * 90) Measurement Scales
 * 91) The Sign Test
 * 92) The Wilcoxon Signed-Rank Test for Location
 * 93) The Median Test
 * 94) The Mann–Whitney Test
 * 95) The Kolmogorov–Smirnov Goodness-of-Fit Test
 * 96) The Kruskal–Wallis One-Way Analysis of Variance by Ranks
 * 97) The Friedman Two-Way Analysis of Variance by Ranks
 * 98) The Spearman Rank Correlation Coefficient
 * 99) Nonparametric Regression Analysis
 * 100) Review Questions and Exercises
 * 101) Survival Analysis:Summary of formulas with R
 * 102) Time-to-Event Data and Censoring
 * 103) The Kaplan–Meier Procedure
 * 104) Comparing Survival Curves
 * 105) Cox Regression: The Proportional Hazards Model
 * 106) Review Questions and Exercises
 * 107) Vital Statistics:Summary of formulas with R
 * 108) Death Rates and Ratios
 * 109) Measures of Fertility
 * 110) Measures of Morbidity
 * 111) Review Questions and Exercises
 * 112) /Further reading/

title: Biostatistics with R


text:
Talk:Ecology/Biogeochemical cycles

I added a sub category(?) Biomes and a roman numeral if anybody wants to add a different biome. Feel free to change this it is only an idea. I cannot figure out how to eliminate the space in my paragraphs next to my pictures. If you know how please do and let me know.==Greg== —The preceding unsigned comment was added by Murphyangus (talk • contribs).

biogeochemical
What would be the impacts if there had been no cycling of the nutrients?

title: Talk:Ecology/Biogeochemical cycles


text:
Biostatistics with R/Import

Why R for biostatistics?
R is superior to common statistical packages such as SPSS, SAS and MINITAB because it is
 * powerful
 * available for many platforms (Mac OS X, Windows, Linux etc.)
 * programmable
 * non-commercial
 * extensively documented

Obtaining R/Installation
You may refer to R FAQ

Data Import
The format of data set available in Wiley's website are CSV, Excel, MINITAB, SAS and SPSS. Although you can import the data saved in Excel, SAS and SPSS into R using the foreign package, you should download the data in CSV format. It is because CSV is the easiest one to process in R.

For example, you would like to import the "Large Data set" data file. The downloaded data file (LDS_C02_NCBIRTH800.csv), assuming stored in the directory "/desktop",can be imported into R as a data.frame called "largedataset" using following syntax: > largedataset <- read.csv("/Desktop/LDS_C02_NCBIRTH800.csv", header=TRUE,na.strings="NA") if you prefer to choose the data file using the standard "point-and-click" GUI way, you may use the function file.choose, i.e. largedataset <- read.csv(file.choose, header=TRUE,na.strings="NA") Now, you should imported the data from the CSV to a data frame called "largedataset". You may try to look inside the data frame by calling its name > largedataset You can access the variable (in computer lingo, column) "sex" inside the largedataset dataframe by largedataset$sex For example, you want to count the frequency of sex > table(largedataset$sex) You can attach the data frame so that you can call the variable directly > attach(largedataset) > table(sex) > detach #cancel attaching

Basic data management
R is designed to be a analysis system instead of a integrated environment such as SPSS. Unlike SPSS, R doesn't have a spreadsheet-like environment for data input. Usually data are entered using different software (e.g. database, spreadsheet software such as OO.o Calc) and then imported to R as described above. For quick one-off calculations, you can do the data entry in R. For example, if you want to calculate the mean age of ten patients (30,31,32,34,35,36,37,30,40,45) you can enter the data into R using the c function. > pt_age <- c(30,31,32,34,35,36,37,30,40,45) You may call the newly created object pt_age by its name... > pt_age ...and then calculate the mean age of the ten patients. > mean (pt_age)

title: Biostatistics with R/Import


text:
LPI Linux Certification/Kernel Runtime Management & Query

Weight: 4

Description: Candidates should be able to manage and/or query a kernel and kernel loadable modules.

 * Key knowledge area(s):
 * Use command-line utilities to get information about the currently running kernel and kernel modules.
 * Manually load and unload kernel modules.
 * Determine when modules can be unloaded.
 * Determine what parameters a module accepts.
 * Configure the system to load modules by names other than their file name.

 * The following is a partial list of the used files, terms and utilities:
 * /lib/modules/kernel-version/modules.dep
 * /etc/modules.conf
 * /etc/modprobe.conf
 * depmod
 * insmod
 * lsmod
 * rmmod
 * modinfo
 * modprobe
 * uname

Obtain information about kernel and modules
To display version of currently running kernel use uname command: uname -r uname -v

lsmod command can be used to display currently loaded kernel modules: $ lsmod Module                 Size  Used by nls_iso8859_1           3261  0 nls_cp437              4931  0 vfat                   9201  0 fat                   48240  1 vfat usb_storage           40172  0 .............

Used by column shows how many modules are dependent on a given one. In example above vfat depends on fat which has to be loaded first.

Loading and Unloading Modules
To load and unload kernel modules you need superuser privileges.

insmod - this command can be used to load kernel module (however use of modprobe is recommended). It is automatically located by the tool but this command works at low level and does not resolve module dependencies. Command below fails because vfat module requires fat to be loaded first: insmod: error inserting '/lib/modules/2.6.35-22-generic/kernel/fs/fat/vfat.ko': -1 Unknown symbol in module When we load fat module first everything works fine:
 * 1) insmod /lib/modules/2.6.35-22-generic/kernel/fs/fat/vfat.ko
 * 1) insmod /lib/modules/2.6.35-22-generic/kernel/fs/fat/fat.ko
 * 2) insmod /lib/modules/2.6.35-22-generic/kernel/fs/fat/vfat.ko

rmmod - this command can be used to remove modules from running kernel. As insmod it will not resolve dependencies: ERROR: Module fat is in use by vfat
 * 1) rmmod fat
 * 1) rmmod vfat
 * 2) rmmod fat

modprobe - this command allows to load and unload modules and automatically resolves dependencies using System.map file (ie. /lib/modules/2.6.31-21-generic/modules.dep). To load module use command with module name as parameter. It will make sure all required modules are loaded as well: To remove module using modprobe command use -r switch: To list all available modules for currently running kernel use -l switch:
 * 1) modprobe vfat
 * 1) modprobe -r vfat

.................. kernel/drivers/net/ne2k-pci.ko kernel/drivers/net/8390.ko kernel/drivers/net/pcnet32.ko kernel/drivers/net/e100.ko kernel/drivers/net/tlan.ko kernel/drivers/net/epic100.ko kernel/drivers/net/smsc9420.ko kernel/drivers/net/sis190.ko kernel/drivers/net/sis900.ko ..................
 * 1) modprobe -l

To determine whether a module can be safely removed use lsmod command described above. You have to make sure that number in the last column is 0 (so that no modules are using the one you are removing)

Getting Information About Modules
modinfo - can be used to display information about a module. Common switches are -a to display author information, -d to display description and -p to display options (parameters) a module accepts: $ modinfo bonding filename:      /lib/modules/2.6.35-22-generic/kernel/drivers/net/bonding/bonding.ko alias:          rtnl-link-bond author:        Thomas Davis, tadavis@lbl.gov and many others description:   Ethernet Channel Bonding Driver, v3.6.0 version:       3.6.0 license:       GPL srcversion:    EC8FCCE4D57BF7B3823F70F depends: vermagic:      2.6.35-22-generic SMP mod_unload modversions 686 parm:          max_bonds:Max number of bonded devices (int) parm:          num_grat_arp:Number of gratuitous ARP packets to send on failover event (int) parm:          num_unsol_na:Number of unsolicited IPv6 Neighbor Advertisements packets to send on failover event (int) parm:          miimon:Link check interval in milliseconds (int) .....................

Creating Name Aliases
To create an alias which used by modprobe command it needs to be added to one of its configuration files. It could be either /etc/modprobe.conf or a file in /etc/modprobe.d/ directory. Sample entries below define eth0 as an alias for bnx2 network card driver and scsi_hostadapter will be an alias for mptbase. Once entries are added one can use modprobe eth0 to load bnx2 network card module. alias eth0 bnx2 alias scsi_hostadapter mptbase


text:
LPI Linux Certification/Boot the System

101.2 Boot the system
(LPIC-1 Version 5.0)

Weight: 3

Description: Candidates should be able to guide the system through the booting process.

Key Knowledge Areas:
 * Provide common commands to the boot loader and options to the kernel at boot time
 * Demonstrate knowledge of the boot sequence from BIOS/UEFI to boot completion
 * Understanding of SysVinit and systemd.
 * Awareness of Upstart.
 * Check boot events in the log files

The following is a partial list of the used files, terms and utilities:
 * BIOS
 * UEFI
 * bootloader
 * kernel
 * SysVinit
 * kernel
 * SysVinit
 * SysVinit
 * SysVinit

Boot Process Overview
When a typical PC is powered on, the BIOS (Basic Input Output Service) detects hardware devices including hard drives and goes through a boot priority list. Assuming we are booting from a hard drive, it will execute the first 512 bytes of code from the first boot disk's MBR (stage1 bootloader). The stage1 boot loader is very basic and its function is to load the stage2 (or stage1.5 in some cases) boot loader. The next step depends on the type of bootloader being used. There are 2 popular boot loaders in Linux: LILO and GRUB

LILO (LInux LOader) is an older boot loader and modern Linux distributions use GRUB rather than LILO but it might still be in use on older systems. When LILO stage2 boot loader is loaded, depending on configuration, it might display a menu that allows a user to specify kernel options. Once kernel options are specified GRUB loads the kernel and initrd and executes the kernel passing any parameters specified by the user. It is important to remember that LILO is not filesystem aware so kernel and initrd are loaded from a predefined location on the hard drive.

GRUB (GRand Unified Bootloader) is a newer and more flexible boot loader. When stage1.5 is loaded it reads /boot partition and loads the stage2 bootloader from there. The stage2 bootloader reads configuration from /boot/grub/grub.conf (RedHat based distributions) or menu.lst (Debian based distributions) and presents user with options (if configured to do so). When the choice is made it loads kernel and initrd from /boot/ partition and executes it passing any options passed by user.

When the kernel loads it detects devices. One of the tasks it has to perform is to mount the root partition. If required hardware and filesystem support is built into the kernel it can be done immediately and /sbin/init program is loaded. This situation is very rare and majority of modern systems will require dynamically loaded modules to be loaded into the kernel in order to mount the root partition. These modules are contained within initial RAM disk (initrd). Once the root partition is ready the kernel runs /sbin/init program which continues to load the operating system.

/sbin/init is the first process started by the kernel and it becomes parent of all other processes. Usually it reads /etc/inittab configuration file however, some newer alternatives like upstart are not using this file any more. In RedHat based system init will execute /etc/rc.d/rc.sysinit and in Debian based systems /etc/init.d/rcS. This script will mount partitions and perform basic system setup. Next it will run all scripts located in /etc/rcX.d/ where X is runlevel number. This could be the default specified in /etc/inittab file or the number provided by administrator as kernel parameter. The last script to run is /etc/rc.local which can be used to add system specific initialization steps. Once this script is executed boot process is complete.

Bootloaders Configuration
LILO is older boot loader and has some limitations. One of them is the fact that kernel and initrd locations are hardcoded into stage2 bootloader. It means that every time new kernel image is added, administrator has to run /sbin/lilo command to reinstall LILO; configuration file used by the /sbin/lilo executable is located in /etc/lilo.conf and might look like:

boot=/dev/hda bitmap=/boot/image.bmp bmp-colors=255,0,255,0,255,0 append="vt.default_utf8=0" map=/boot/System.map install=/boot/boot.b prompt timeout=50 vga=773 image=/boot/vmlinuz-2.0.36 label=linux root=/dev/hda2 read-only
 * 1) begin LILO global section
 * 1) VESA framebuffer console @ 1246x768x256
 * 1) end LILO global section
 * 2) Linux bootable partition config begins
 * 1) Linux bootable partition config ends
 * 2) second bootable partition config begins...

 * boot - this parameter specifies where LILO will be installed. In example above it will be MBR of /dev/hda disk. (or in some cases /dev/sda).
 * bitmap - it will append a custom background image for your distribution.
 * bmp-colors - it will set other background color scheme to the loader.
 * append - will provide any additional commands to the kernel during boot for a specific setup, adding or removing a kernel feature or module.
 * map - the map file is automatically generated by LILO and is used internally. It is recommended not to change this option.
 * install - specifies which image to use for boot sector. Again it is not recommended to change this parameter.
 * prompt - this options enabled administrator to append kernel command line options when system boots.
 * timeout - specifies prompt timeout in tenths of a second so in example above timeout is set to 5 seconds.
 * vga - in some systems this will indicate what video resolution the boot process will be in.
 * image - kernel location. (use different kernel names for separate boot sections)
 * label - name which will be displayed in LILO menu during boot.
 * root - root filesystem location.
 * read-only - see kernel parameters section below

Grub offers many benefits over LILO. One of them is fact that it offers bash-like command line which can be used to dynamically change kernel or initrd image used. Sample configuration file is listed below: default        0 timeout        5 title          Debian GNU/Linux, kernel 2.6.26-2-686 root           (hd0,0) kernel         /vmlinuz-2.6.26-2-686 root=/dev/mapper/Disk-root ro quiet initrd         /initrd.img-2.6.26-2-686

First line specifies default image, in this case image number 0 which is the only one configured. Second line specifies prompt timeout in seconds. If it is set to 0 grub will immediately boot default image without any prompt. Next 4 lines define menu entry:
 * title - name of menu entry
 * root - partition on which to find kernel and initrd. In example above (hd0,0) is first partition on the first disk
 * kernel - kernel image to be loaded together with kernel parameters. Kernel's location is relative to the top of root partition, usually /boot (do not confuse with linux root partition or /)
 * initrd - initial ramdisk image.

It is common for grub to contain many title/root/kernel/initrd sets for different kernel versions.

Kernel Parameters
As mentioned above kernel requires some arguments which can be configured in grub, LILO or dynamically appended by user during system startup. List of common kernel parameters below:
 * root=  - specifies root filesystem which will be mounted as /. It can be partition (ie. root=/dev/sda2), disk label (root=LABEL=root_partition) or logical volume (root=/dev/mapper/vg_root-root)
 * ro or read-only - instructs the kernel to mount root filesystem as read only. This allows filesystem to be checked before partition is remounted read-write. This option is used in almost all cases
 * quiet - do not print diagnostic messages to the screen
 * single - boot system into single user mode (runlevel 1)
 * console= - tells kernel to send output to console. For example to send it to serial port use console=/dev/ttyS0
 * init=/ - can be used to specify replacement for /sbin/init process for example to get root shell without password use init=/bin/bash

Checking Logs
All kernel messages diagnostic messages are send to kernel ring buffer. Its content can be reviewed using dmesg command, however the output can tedious and is best to use dmesg | less, use arrow keys to scroll verticle and Q to exit dmesg. Bear in mind that this buffer has limited capacity and when new messages come in the oldest ones could be removed. Once all partitions are mounted one of init scripts will write content of kernel buffer to a logfile, normally /var/log/messages so that diagnostic messages are available when needed.

title: LPI Linux Certification/Boot the System


text:
LPI Linux Certification/Change Runlevels And Shutdown Or Reboot System

101.3 Change runlevels / boot targets and shutdown or reboot system
(LPIC-1 Version 5.0)

Weight: 3

Description: Candidates should be able to manage the SysVinit runlevel or systemd boot target of the system. This objective includes changing to single user mode, shutdown or rebooting the system. Candidates should be able to alert users before switching runlevels / boot targets and properly terminate processes. This objective also includes setting the default SysVinit runlevel or systemd boot target. It also includes awareness of Upstart as an alternative to SysVinit or systemd.

Key knowledge area(s):
 * Set the default runlevel or boot target.
 * Change between runlevels / boot targets including single user mode.
 * Shutdown and reboot from the command line.
 * Alert users before switching runlevels / boot targets or other major system event.
 * Properly terminate processes.
 * Awareness of acpid.

The following is a partial list of the used files, terms and utilities:

Runlevels Overview
Runlevels are used in Linux to customize the way operating system is initialized. Runlevel defines which services are started automatically during initialization. Each runlevel has a number (and possibly alias) which defines it. Common runlevel number can be found in a table below, unfortunately some of the differ between RedHat and Debian based distributions:

Setting Default Runlevel
Default runlevel is controlled in /etc/inttab file in most of the distributions however this is currently changing as some new Linux distributions start using more advanced event driven upstart replacement for traditional init program. In /etc/inittab the following line controls default runlevel (example from Debian with runlevel 2 set as default): id:2:initdefault: When operating system loads /sbin/init program it will read the line above and determine that it should use runlevel 2 (unless another runlevel number was passed as kernel parameter). Following this init will run all scripts from /etc/rcX.d/ directory where X is runlevel number. Sample content of the directory might look similar to: -rw-r--r-- 1 root root 556 2008-08-12 15:09 README lrwxrwxrwx 1 root root 17 2010-01-07 22:08 S10rsyslog -> ../init.d/rsyslog lrwxrwxrwx 1 root root 15 2010-01-07 22:10 S12acpid -> ../init.d/acpid lrwxrwxrwx 1 root root 15 2010-05-09 11:39 S15bind9 -> ../init.d/bind9 lrwxrwxrwx 1 root root 13 2010-01-07 22:40 S16ssh -> ../init.d/ssh lrwxrwxrwx 1 root root 15 2010-01-07 22:15 S20exim4 -> ../init.d/exim4 lrwxrwxrwx 1 root root 20 2010-01-07 22:15 S20nfs-common -> ../init.d/nfs-common lrwxrwxrwx 1 root root 27 2010-01-07 23:10 S20nfs-kernel-server -> ../init.d/nfs-kernel-server lrwxrwxrwx 1 root root 23 2010-01-07 22:15 S20openbsd-inetd -> ../init.d/openbsd-inetd lrwxrwxrwx 1 root root 13 2010-01-07 22:15 S89atd -> ../init.d/atd lrwxrwxrwx 1 root root 14 2010-01-07 22:08 S89cron -> ../init.d/cron lrwxrwxrwx 1 root root 17 2010-01-07 22:59 S91apache2 -> ../init.d/apache2 lrwxrwxrwx 1 root root 18 2010-01-07 22:08 S99rc.local -> ../init.d/rc.local lrwxrwxrwx 1 root root 19 2010-01-07 22:08 S99rmnologin -> ../init.d/rmnologin lrwxrwxrwx 1 root root 23 2010-01-07 22:08 S99stop-bootlogd -> ../init.d/stop-bootlogd

All services from the directory will be run in order starting from the lowest number to the highest. As you might have notices all file in the /etc/rcX.d/ directory are symbolic links to startup scripts in /etc/init.d/. When operating system enters the runlevel init program passes "start" parameter to all scripts prefixed with "S" character and "stop" to all scripts prefixed with "K". In above example one of the first programs to run is rsyslog: S10rsyslog -> ../init.d/rsyslog This will cause init to execute the following command: /etc/init.d/rsyslog start

Above example is runlevel 2 from Debian which is full multiuser so no services have to be killed however if we look at runlevel 1 on the same system it looks very differently: lrwxrwxrwx 1 root root 17 2010-01-07 22:59 K09apache2 -> ../init.d/apache2 lrwxrwxrwx 1 root root 13 2010-01-07 22:15 K11atd -> ../init.d/atd lrwxrwxrwx 1 root root 14 2010-01-07 22:08 K11cron -> ../init.d/cron lrwxrwxrwx 1 root root 15 2010-01-07 22:15 K20exim4 -> ../init.d/exim4 lrwxrwxrwx 1 root root 20 2010-01-07 22:15 K20nfs-common -> ../init.d/nfs-common lrwxrwxrwx 1 root root 23 2010-01-07 22:15 K20openbsd-inetd -> ../init.d/openbsd-inetd lrwxrwxrwx 1 root root 27 2010-01-07 23:10 K80nfs-kernel-server -> ../init.d/nfs-kernel-server lrwxrwxrwx 1 root root 17 2010-01-07 22:15 K81portmap -> ../init.d/portmap lrwxrwxrwx 1 root root 13 2010-01-07 22:40 K84ssh -> ../init.d/ssh lrwxrwxrwx 1 root root 15 2010-05-09 11:39 K85bind9 -> ../init.d/bind9 lrwxrwxrwx 1 root root 15 2010-01-07 22:10 K88acpid -> ../init.d/acpid lrwxrwxrwx 1 root root 17 2010-01-07 22:08 K90rsyslog -> ../init.d/rsyslog -rw-r--r-- 1 root root 369 2007-12-23 11:04 README lrwxrwxrwx 1 root root 19 2010-01-07 22:08 S30killprocs -> ../init.d/killprocs lrwxrwxrwx 1 root root 16 2010-01-07 22:08 S90single -> ../init.d/single

When system enters runlevel 1 it will kill all services beginning with "K" leaving bare minimum running.

Changing Runlevels, shutting down and rebooting system
init and telinit - telinit command is just a link to init, functionality of both is the same. They can be used to change the current runlevel. They take only one parameter, which is the new runlevel number. Example usage: Change runlevel single user mode: init 1 Runlevel 6 is reboot. init can be used to reboot the system: telinit 6 To shutdown we go to runlevel 0 init 0

shutdown - shutdown command can be used to reboot, shutdown and send a warning message to all logged in users. /sbin/shutdown [-t sec] [-arkhncfFHP] time [warning-message] Common options:
 * -h - halt or power off after shutdown
 * -r - reboot after shutdown
 * -k - Don't really shutdown; only send the warning message to everybody

Examples: Shutdown in 5 minutes and send warning message shutdown -h +5 System is going down for maintenance Reboot immediately shutdown -r now Do not reboot or shutdown, only send message to users shutdown -k Make sure you keep your password safe Shutdown system at 23:59 shutdown -h 23:59 This system is going down for maintenance at 23:59


text:
LPI Linux Certification/Manage Printers And Printing

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 2

Description: Candidates should be able to manage print queues and user print jobs using CUPS and the LPD compatibility interface.

Key Knowledge Areas:
 * Basic CUPS configuration (for local and remote printers).
 * Manage user print queues.
 * Troubleshoot general printing problems.
 * Add and remove jobs from configured printer queues.

The following is a partial list of the used files, terms and utilities:
 * CUPS configuration files, tools and utilities
 * legacy interface
 * legacy interface


text:
LPI Linux Certification/Customize And Use The Shell Environment

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 4

Description: Candidates should be able to customize shell environments to meet users' needs. Candidates should be able to modify global and user profiles.

Key Knowledge Areas:
 * Set environment variables (e.g. ) at login or when spawning a new shell.
 * Write Bash functions for frequently used sequences of commands.
 * Maintain skeleton directories for new user accounts.
 * Set command search path with the proper directory.

The following is a partial list of the used files, terms and utilities:


text:
LPI Linux Certification/Customize Or Write Simple Scripts

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 4

Description: Candidates should be able to customize existing scripts, or write simple new Bash scripts.

Key Knowledge Areas:
 * Use standard sh syntax (loops, tests).
 * Use command substitution.
 * Test return values for success or failure or other information provided by a command.
 * Execute chained commands.
 * Perform conditional mailing to the superuser.
 * Correctly select the script interpreter through the shebang line.
 * Manage the location, ownership, execution and suid-rights of scripts.

The following is a partial list of the used files, terms and utilities:


text:
LPI Linux Certification/Manage User And Group Accounts And Related System Files

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 5

Description: Candidates should be able to add, remove, suspend and change user accounts.

Key Knowledge Areas:
 * Add, modify and remove users and groups.
 * Manage user/group info in password/group databases.
 * Create and manage special purpose and limited accounts.

The following is a partial list of the used files, terms and utilities:


text:
LPI Linux Certification/Automate System Administration Tasks By Scheduling Jobs

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 4

Description: Candidates should be able to use cron and systemd timers to run jobs at regular intervals and to use at to run jobs at a specific time.

Key Knowledge Areas:
 * Manage cron and at jobs.
 * Configure user access to cron and at services.
 * Understand systemd timer units.

The following is a partial list of the used files, terms and utilities:


text:
LPI Linux Certification/Maintain System Time

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 3

Description: Candidates should be able to properly maintain the system time and synchronize the clock via NTP.

Key Knowledge Areas:
 * Set the system date and time.
 * Set the hardware clock to the correct time in UTC.
 * Configure the correct timezone.
 * Basic NTP configuration using  and.
 * Knowledge of using the  service.
 * Awareness of the  command.

The following is a partial list of the used files, terms and utilities:


text:
LPI Linux Certification/Mail Transfer Agent (MTA) Basics

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 3

Description: Candidates should be aware of the commonly available MTA programs and be able to perform basic forward and alias configuration on a client host. Other configuration files are not covered.

Key Knowledge Area(s):
 * Create e-mail aliases.
 * Configure e-mail forwarding.
 * Knowledge of commonly available MTA programs (postfix, sendmail, exim) (no configuration).

The following is a partial list of the used files, terms and utilities:
 * sendmail emulation layer commands
 * sendmail emulation layer commands


text:
LPI Linux Certification/Perform Security Administration Tasks

Weight: 3

Description: Candidates should know how to review system configuration to ensure host security in accordance with local security policies.

 * Key knowledge area(s):
 * Audit a system to find files with the suid/sgid bit set.
 * Set or change user passwords and password aging information.
 * Being able to use nmap and netstat to discover open ports on a system.
 * Set up limits on user logins, processes and memory usage.
 * Basic sudo configuration and usage.

 * The following is a partial list of the used files, terms and utilities:
 * find
 * passwd
 * lsof
 * nmap
 * chage
 * netstat
 * sudo
 * /etc/sudoers
 * su
 * usermod
 * ulimit


text:
LPI Linux Certification/Setup Host Security

Detailed Objectives
(LPIC-1 Version 5.0)

Weight: 3

Description: Candidates should know how to set up a basic level of host security.

Key Knowledge Areas:
 * Awareness of shadow passwords and how they work.
 * Turn off network services not in use.
 * Understand the role of TCP wrappers.

The following is a partial list of the used files, terms and utilities:


text: Biostatistics with R/Descriptive Statistics


text:
Past LSAT Explained/PrepTest 45/Method of Argument

attempt to undermine the analysts' argument by questioning the truth of its premises

attempts to undermine the analysts' argument by suggesting that the analysts present it for self-serving reasons

attempts to undermine the analysts' argument by drawing an alternative conclusion from the analysts' premises

argues that the analysts' conclusion is basically right, but suggests that it is somewhat too optimistic

argues in favor of the analysts' conclusion, but does so on the basis of a different body of evidence

proposing an alternative course of action for achieving the objectives of the proposal being argued against

raising considerations in order to show that the proposal being argued against, if strictly implemented, would lead to absurd consequences

using specific examples in order to show that an alternative to the proposal being argued against would better achieve the ends to which the original proposal was directed

introducing a case analogous to the one under consideration to show that a general implementation of the proposal being argued against would be impossible

questioning the motivation of those who made the proposal being argued against

|45/Method of Argument


text:
Talk:Mirad/Orthography and Pronunciation

Untitled
I think that the pronunciation guide on how to say the vowels needs some work. I had to look up the pronunciation of many, and even then couldn't get a clear idea. Could someone put in IPA equivalents when they have the chance? Talkie Toaster 12:55, 24 September 2007 (UTC)


text:
Power Electronics

Power Electronics is the study of switching electronic circuits in order to control the flow of electrical energy. Power Electronics is the technology behind switching power supplies, power converters, power inverters, motor drives, and motor soft starters.

Some discrete components used in power electronics
Diodes

Schottky Diodes

Power Bipolar Junction Transistors

MOSFETs

Thyristors:

Silicon Controlled Rectifier (SCR)

Gate Turn-Off Thyristors

Insulated Gate Bipolar Transistors (IGBT)

Gate-Commutated Thyristors

Heatsink
Motors and most other actuation devices are typically indirectly connected to the power supply through a power transistor which acts as a switch, either allowing energy to flow from the power supply to the motor, or disconnecting the motor from power. (The CPU, also connected to the transistor, chooses exactly when to turn it on or off).

When the switch is turned on, most of the power coming from the power supply goes to the motor. Unfortunately, some of the power is trapped by unwanted parasitic resistance in the power transistors, heating them up. Often a heatsink is necessary to keep the transistor from overheating and self-destructing. Practically all modern desktop or laptop PCs require a heat sink on the CPU and on the graphics chip. (A typical robot requires a heatsink on its power transistors, but not on its small CPU).

"Application note AN533: thermal management precautions for handling and mounting"  describes "how to calculate a suitable heatsink for a semiconductor device". It looks like this applies to all power semiconductors -- FET, BJT, Triac, SRC, etc. It gives thermal resistance for DPAK and D2PAK for FR4 alone, FR4 plus heatsink, Insulated Metallic Substrate (IMS), and IMS plus heatsink.

The principles behind heatsinking these power semiconductors are the same as the principles behind PC CPU heatsinking.

Triacs

Triacs have 3 pins. Triacs look like and are controlled much like PNP power transistors. Triacs can control AC power in a circuit much like a relay -- it's either on (shorted) or off (open).

Turning on a triac is easy: Typically digital logic is connected so its Vdd is connected to the triac A1 pin. Some digital logic output pin is connected to a small resistor connected to the triac gate pin. When the digital logic pulls the gate pin low (towards Vss), the triac is triggered and turns all the way on.

As long as the triac is on, the A1 and A2 pins act like they are shorted together. Current can flow in both directions through the triac -- whether A2 is higher or lower than the A1 voltage.

Turning the triac off is a little more difficult. First the digital logic output drives the gate pin high (so it is the same voltage as the common A1 pin). But the triac remains on until the current through the triac drops to less than the holding current. Normally triacs are used with 50 Hz or 60 Hz AC, so the triac may stay on as long as 10 ms after the digital logic tries to turn it off.

After the triac is off, A2 acts like is disconnected and isolated from the rest of the triac (as long as the external circuit doesn't drive it outside its voltage rating, typically plus or minus several hundred volts).

Driving a triac is very similar to driving PNP transistor -- "gate" analogous to "base", "A1" analogous to "emitter", "A2" analogous to "collector".

By far, the most common silicon device to drive AC loads connected to mains voltage is the triac. A triac works better than a BJT or a FET transistor as a switch when controlling AC power. A triac can remain off while A2 can swing up and down hundreds of volts (relative to A1 and the gate). It's difficult to keep a BJT or FET transistor from spontaneously turning on in the "reverse" direction.

PNP transistors work better than triacs as switches when controlling DC power. A PNP transistor can quickly turn off even when full current is flowing through them. A triac will stay on indefinitely when DC current flows through it.

A "snubberless triac" or "logic level triac" will not turn on with positive gate current when the A2 lead is at a negative voltage (relative to A1), but they will turn on with a positive gate current when the A2 lead is at a positive voltage. Some "standard" triacs will turn with a positive gate current (like a power NPN transistor) no matter if A2 is positive or negative, but such "positive gate current triggering" is not recommended. The "negative gate current triggering" is preferred.

Power Electronic Converters
AC-to-DC Converter (Rectifiers)

DC-to-AC Converter (Inverter)

DC-to-DC Converter (Chopper)

AC-to-AC Converter(Cycloconverter)

Soft Starters
Soft Starters

Introduction
In industrial applications, almost everything uses a motor, in fact, motors may account for up to 80% of our country’s energy usage. There are generally three different ways to start a motor: full-voltage, reduced voltage, and inverter. A full voltage, across-the-line, or direct on-line (DOL) start uses a contactor, which is a heavier duty three-phase relay. Reduced voltage starting can be accomplished via several different ways: auto-transformer, wye-delta, primary resistor/reactor, or with a solid state soft starter. Inverters are generally referred to as drives. This paper focuses on solid state soft starters (referred to as soft starter only from here on): what they are, why they are used, their construction, and applications.

What is a soft starter?
A soft starter is a solid state motor starter that is used to start or stop a motor by notching the voltage waveform, thereby, reducing the voltage to each phase of a motor and gradually increasing the voltage until the motor gets up to full voltage/speed all at a fixed frequency. The profile of the increase of voltage depends on the application. The voltage is reduced and controlled by 3 pairs of back-to-back silicon-controlled rectifiers (SCRs) (Fig. 1), which are a type of high speed thyristor. A soft starter takes the place of a contactor and can also take the place of an overload relay in a standard motor starting application. Fig. 1 demonstrates the configuration of a soft starter controlling a line or wye connected motor from a three-phase source.

Figure 1: Standard Soft Starter Topology

Why use a soft starter?
In general, there are two reasons to use a soft starter: the power distribution network may not be able to handle the inrush current of the motor and/or the load cannot handle the high starting torque. As a rule of thumb, a motor utilizes around 600-800% of its full load current (FLA) to start. This current is referred to as inrush current or locked-rotor current. Some systems, when the power is switched on, briefly pull 50 times the normal operating current. If a large motor is on a smaller power distribution network or on a generator system, this inrush current can cause the system voltage to dip or to “brown out.” Brown outs can cause problems with whatever else is connected to the system, such as computers, lights, motors, and other loads. Another problem is that the system may not even be able to start the motor because it cannot source or supply enough current. Most industrial businesses run during the day can be fined or charged extra (Peak Demand charges) during this peak usage time for large transients caused by large horsepower (HP) motor start ups. These Peak Demand charges can add up very quickly, especially if the motor needs to be started multiple times during any given day. The inrush current can be controlled one of two ways with a soft starter: either with a current limit (discussed later) or reduced linearly with the reduced voltage, and follows this approximation: Applications such as conveyors may not be able to handle a sudden jolt of torque from an across-the-line start. Utilizing soft starters reduces the wear and tear on belts, conveyors, gears, chains, and gearboxes by reducing the torque from the motor. The torque decreases as a square of the reduced voltage, and follows this approximation: Since soft starters are generally controlled and monitored by a microprocessor, a soft starter can add many features and protections fairly easily. It can offer a choice of the starting time, limited speed control, and energy savings. Power monitoring, such as three-phase current, three-phase voltage, power, power usage, power factor, and motor thermal capacity usage, can be implemented with current transformers, a voltage meter, and an internal clock. With the above implementations, protection, for the motor or the soft starter, from the items listed below (Table 1) can also be offered by stopping the firing of the SCRs, dropping out the bypass contactor (a contactor that carries the motor load after the motor is up-to-speed), and/or alerting a user via some form of communications with the microprocessor and another computer.

Possible protections that can be offered by a soft starter
 * SCR Open Gate
 * Phase Unbalance
 * Power Loss
 * Undervoltage
 * Overtemperature
 * Jam
 * Underload
 * Phase Reversal
 * Overload
 * Overvoltage
 * Stall
 * Excessive Starts/Hr
 * Line Loss
 * Ground Fault
 * Bypass Failure

Construction
Generally, a soft starter is constructed with three pairs of SCRs reverse parallel connected to allow the current to flow to or from the motor. Soft starters can be made by controlling just one or two phases, but this paper will focus on the most prevalent implementation, three-phase control. Each phase of a soft starter can be controlled with an SCR pair reverse parallel connected (Fig. 2), an SCR/diode pair reverse parallel connected (Fig. 3), or a triac (Fig. 4), depending on cost and/or quality. The most prevalent switch in industry is probably the SCR pair and will also be the focus of this paper. Soft starters are used almost exclusively for starting and stopping and not during the run time because of the heat loss through the SCRs from the voltage drop across them. Figure 2: SCR Pair Figure 3: SCR/Diode Pair Figure 4: Triac

A standard assembly of a soft starter uses one SCR pair per phase and once the voltage gets to within approximately 1.1V of full voltage (depending on the voltage drop across the SCR) a bypass contactor (internal or external to the soft starter), running parallel to the SCR pairs, pulls in (Fig. 5). Once pulled in the SCRs stop firing. Typically, the bypass contactor is much smaller than compared to what is needed for a full voltage start as the contacts only need to be able to handle the full load current of the motor. Since the mechanical contacts cannot handle the inrush current, the SCRs must be sized correctly to handle the motor’s locked-rotor current. Figure 5: Standard Soft Starter Topology With Bypass

The transition from SCRs to bypass should also be near full speed to minimize the jump in current (Fig. 6). Fig. 7 shows a transition at slow speed; the transition has a jump in current near the locked-rotor or starting current, defeating the purpose of a soft starter. Figure 6: Near Full Speed Transition [7] Figure 7: Low Speed Transition [7]

Control
A soft starter reduces the voltage by “notching” the applied sinusoidal waveform, simulations of which can be seen in Figures 8-13. A notch is a non-technical term for the zero voltage area in the middle waveform seen in Fig. 9. Fig. 9 also shows the forward firing SCR pulses in green and the reverse firing pulses in blue to notch the output voltage. Fig. 10-13 show a progression from a 90º firing angle to 30º. As the notch decreases in size, the Vrms increases along with Irms. An initial voltage, determined by the user, is ramped up to full voltage by varying the firing angle depending on the preset profile of the soft starter. Soft starters can be controlled via open-loop or closed-loop control. Figure 8: Single Phase Simulation Figure 9: Single Phase Simulation (90º Firing Angles, Voltage, and Current) Figure 10: 90º ~ 341Vrms Figure 11: 70º ~ 405Vrms Figure 12: 50º ~ 452Vrms Figure 13: 30º ~ 469Vrms

Open-Loop and Closed-Loop
An example of open loop control is the voltage ramp (Fig. 14), the voltage ramps from an initial voltage to full voltage in a linear fashion without regards to the load. Pump start is another form of open-loop control. The pump starter’s firing circuit ramps up the voltage with a profile that allows the speed/torque to ramp (Fig. 15) in a more efficient manner and helps protect against water hammering, a common problem in pump applications. Fig. 14-15 also show examples of soft stopping. Applications such as current limit (Fig. 16) use feedback from the motor or the line current/voltage to change the firing angle of the SCRs as necessary, hence closed-loop. All control schemes listed monitor back EMF of the motor as to not become unstable. Figure 14: Voltage Ramp [7] Figure 15: Pump Start [7] Figure 16: Current Limit [7]

Applications
Soft starters can be made for a reversing application by adding two extra SCR pairs that switch two phases. For example, line phase “b” is connected to load phase “c” and vice versa. L2 (“b”) is connected to T3 (“c”) and L3 (“c”) is connected to T2 (“b”) in Fig. 17. A delta configuration motor can also be controlled with a soft starter (Fig. 18), but it will see more current than a line connected motor. As a way to get around the larger current switching, a soft starter can be wired “inside the delta,” as can be seen in Fig. 19. Wiring in this configuration will allow the soft starter to control a larger motor than even line connected by a √3 advantage. For instance, an “inside the delta” soft starter can switch a 277A load versus a line connected soft starter needs to be able to switch 480A to control the same rated motor load. A disadvantage of “inside the delta” is that it requires six leads coming from the motor which can be an added expense with larger HP motors. Figure 17: Reversing Soft Starter Topology Figure 18: Delta Soft Starter Topology Figure 19: "Inside the Delta" Topology

Above are some physical variations of soft starter applications. In contrast, kick starting and low speed ramps are some other applications that can be implemented via different programming of SCR firing angles.

High Inertia Load Characteristics
Below are some calculated simulations of different applications of soft starters with high inertia loads. Table 2 holds the properties the motor simulated. Fig. 20-21 shows a general full voltage start for comparison with a motor that has a locked-rotor current LRA that is 600% of the FLA and a locked-rotor torque LRT or starting torque that is 180% of the full load torque. See Appendix Fig. 35 for an explanation of the %Current & % Torque vs. Speed curves. Table 2: Simulated Motor Motor Information	Load Information Motor Type	NEMA B	Load Type	High Inertia Rated HP	200	Load Inertia	36000 Rated Speed	1750	Load Speed	605 Frequency	60	%Load Factor	80% LRA %	600%	%Inefficiency	30% LRT%	180%
 * 1) of Poles	4	Motor Inertia	100

Motors must be sized appropriately to have enough torque with respect to its load or the motor will not be able to start, irregardless of starter type. Figure 20: Full Voltage Starting [8] Figure 21: Full Voltage Starting [8]

As you can see in Fig. 22, the starting current is reduced from 600% to roughly 400% and the initial starting torque is set to 50%. The initial torque for this motor application cannot be any less than the load torque, or a stall condition may occur (discussed later). Figure 22: Soft Start Motor Starting Characteristics [8]

In a current limit start (Fig. 23), the current is limited to a specified value, in this instance 450% of the FLA. The lowest level to which the current can be limited depends on the motor torque. Again, caution needs to taken in setting the current limit to make sure the motor torque does not dip below the load torque to avoid stall conditions. Figure 23: Current Limit Motor Starting Characteristics [8] High Inertia Load Speed Characteristics Fig. 24-25 are for comparison to an across-the-line start. Figure 24: Soft Start [8] Figure 25: Current Limit Start [8]

High Inertia Stall Conditions
A stall occurs when the motor torque cannot overtake the load torque and the motor cannot rotate. When this happens, the motor will draw more current than the FLA to try to turn the load, again, defeating the purpose of the soft starter. Motor stalls are possible if the motor torque dips below the load torque; for a high inertia load, the starting load torque is quite high and stays relatively high. Fig. 26-27 show possible stall conditions (highlighted by arrows) for a soft start or a current limit start. Fig. 26-27 and 32 may be slightly misleading because once the motor stalls the speed will not increase. Soft Starter Settings Starting Type	Soft Start Initial Torque %	40% Figure 26: Soft Start Stall [8] Soft Starter Settings Starting Type	Current Limit Initial Current%	300% Figure 27: Current Limit Stall [8]

Pump Application Load Characteristics
The pump application simulation uses the same motor characteristics as the previous high inertia application but is connected to a pump. A pump load starts with almost no load torque and it increases with speed. The red line in Fig. 28 shows the load torque. Motor Information	Load Information Motor Type	NEMA B	Load Type	Pump Rated HP	200	Load Inertia	36000 Rated Speed	1500	Load Speed	605 Frequency	60	%Load Factor	80% LRA %	600%	%Inefficiency	30% LRT%	180%
 * 1) of Poles	4	Motor Inertia	100

The closer the motor torque can get to the pumps torque with out dipping below it, the more potential for energy savings. With almost no starting load torque a soft start can be set much lower than in a high inertia load. Fig. 28 is set to 2% of locked-rotor torque. Figure 28: Pump Soft Start [8]

Using a current limit start with this application, the motor torque is kept closer to the load torque (highlighted by arrows) than with the soft start above (highlighted by arrows), allowing even more energy savings. Fig. 29 is set to 225% of the locked-rotor torque. Figure 29: Pump Current Limit [8]

Pump Application Speed Characteristics Fig. 30-31 are speed vs. time curves for comparison to the across-the-line start. Figure 30: Soft Start [8] Figure 31: Current Limit [8]

Pump Application Stall Conditions
With a pump application there is almost no starting torque, and the soft start option almost cannot fault. However, the current limit has an inherent dip in its starting profile, and again, caution must be taken to avoid stall conditions. Fig. 32 has a current limit set to 200% of the FLA and the motor starts to stall at around 50% of its full speed (highlighted by arrow). Figure 32: Pump Stall [8]

Conclusion
A soft starter is a versatile starter that can take many forms and be used to start many different applications. Along with protecting applications such as belt conveyors and saw mills, it can help save a great deal of energy by reducing the starting current and starting torque and help stop numerous conditions that are damaging to motors. Appendix Figure 33: Kickstart Profile Figure 34: Low Speed and Low Speed Revering Profile Figure 35: Speed/Current vs. Torque Curve Explanation

other soft starters
Soft start circuits are useful in many applications, even ones that don't use motors.

For example, when a simple switching regulator is first connected to a simple solar array, the array voltage drops, causing the regulator to pull more current, causing the array voltage to drop further, causing the regulator to pull even more current, and so on. The result is "voltage collapse" with the system locking up in an undesirable state.

style="text-align:center;" | Soft-start circuits are one solution to this latchup problem.

title: Power Electronics


text:
Past LSAT Explained/PrepTest 45/Attitude

enthusiastic support

bemused dismissal

reasoned disagreement

strict neutrality

guarded agreement

|45/Attitude


text:
User talk:Sivapriyan

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.– Mike.lifeguard  | talk 13:36, 24 September 2007 (UTC)

title: User talk:Sivapriyan


text:
User talk:204.218.240.61

 * – Mike.lifeguard  | talk 13:53, 24 September 2007 (UTC)

title: User talk:204.218.240.61


text:
MediaWiki:Common.js/NavigationTabs.js

// Navigate Tabs. Allows for lots of information to be displayed on a page in a more compact form. // Maintained by User:Darklama function Navigate_Tabs {	function clicked_tab( e ) {		var $target = $( e.target ), id = e.target.hash;

if ( !$target.is( 'a' ) || !id ) { return true; }

$target = $(this).siblings( id );

if ( !$target.hasClass( 'contents' ) || !$target.parent.hasClass( 'navtabs' ) ) { return true; }

e.preventDefault;

$target.parent.children( '.tabs' ).find( 'a' ).each( function {			if ( this.hash !== id ) {				$(this).parent.addClass( 'inactive' ).removeClass( 'selected' );			} else {				$(this).parent.addClass( 'selected' ).removeClass( 'inactive' );			}		} );

$target.parent.children( '.contents' ).hide; $target.show; }

mw.util.$content.find('.navtabs').each( function {		var $this = $(this), $p = $this.children( 'p' ), $tabs, $any;

// remove any surrounding paragraph first $p.has( '.tabs' ).before( $p.children( '.tabs' ) ).remove;

// deal with clicks, and show default $tabs = $this.children( '.tabs' ).click( clicked_tab ); $any = $tabs.children( '.selected' ).find('a[href^="#"]').click;

if ( !$any.length ) { $tabs.children(':first-child').find('a[href^="#"]').click; }	} ); } $(document).ready(Navigate_Tabs);

title: MediaWiki:Common.js/NavigationTabs.js


text:
Talk:Adventist Youth Honors Answer Book/Recreation/Dutch Oven Cooking

Advent Source lists a patch (image yet unknown) Catalog: #005475

Pathfinders Online has PDF requirements


text:
GIMP/Body Shifting

This is more or less how magazines are manipulating their images so that the models look "perfect" in their eyes and other areas. A nice example of this in Adobe Photoshop is available at. I strongly recommend using the latest version of The GIMP.

Load an image that you want to manipulate. Go in   Filters > Distorts > IWarp (for Adobe Photoshop and Photoshop Elements users, this is the equivalent of the "Liquify" filter).

You manipulate the image in the preview. In the "Deform Mode" section, choose "Move", this will deform the image in the direction of the movement of the mouse. For the purpose of body shifting, "Remove", "Grow" and "Shrink" are the other interesting buttons. They do what it says on the tin. Adjust "Deform radius" and "Deform amount" to your likings, depending how subtle your edits have to be. Also the "Swirl" options produce interesting results. If you want to start over (e.g. you messed your image up) click on "Reset".

title: GIMP/Body Shifting


text:
Signal Processing/Steepest Descent Algorithm

Steepest Descent
The steepest descent algorithm is an old mathematical tool for numerically finding the minimum value of a function, based on the gradient of that function. Steepest descent uses the gradient function (or the scalar derivative, if the function is single-valued) to determine the direction in which a function is increasing or decreasing most rapidly. Each successive iteration of the algorithm moves along this direction for a specified step size, and the recomputes the gradient to determine the new direction to travel.

The method of steepest descent is a useful tool for signal processing because it can be applied iteratively.

We can apply the steepest descent algorithm to the Wiener filter in such a way that at each new step we can calculate a new set of filter coefficients. Using the steepest descent method, we can approach a minimum error value in relatively few iterations, and we can track a signal that changes in time to apply new minimum coefficients to each new version of the signal. It is important to use a steepest descent, or other fast minimization algorithm so that the filter coefficients can be updated more quickly then the next input sample is received.

Steepest Descent Algorithm
The steepest descent algorithm can be formulated as follows:

 * $$\mathbf{a}(n + 1) = \mathbf{a}(n) + \mu;[\nabla J(\mathbf{a})]$$

For mathematical convenience, it is often useful to add in an additional 1/2 term:

 * $$\mathbf{a}(n + 1) = \mathbf{a}(n) + \frac{1}{2}\mu;[\nabla J(\mathbf{a})]$$

Steepest Descent Wiener Filter
We can apply the steepest descent algorithm to the Wiener filter so that at each iteration the tap-weight vector a will approach the optimum Wiener tap weight vector ao. If p is the cross-correlation vector between the filter input x(n) and the desired response d(n), and if R is the cross-correlation matrix of the filter input u(n), then applying the steepest descent algorithm we obtain:

 * $$\mathbf{a}(n + 1) = \mathbf{a}(n) + \mu[\mathbf{p} - \mathbf{R} \mathbf{a}(n)]$$

This update algorithm is especially convenient since it is possible to parallelize large portions of the correlation calculations.

Stability
The steepest descent algorithm has the potential to diverge or become unstable unless:

 * $$0 \le \mu$$

and

 * $$-1 < 1 - \mu \lambda_k < 1$$

Where λk are the eigenvalues of R. If these two conditions are satisfied, the algorithm should converge towards an optimal value.

Performance
A higher value of μ will cause the algorithm to converge more quickly.


text:
Radiation Oncology/CSI

 * McGill; 2006 PMID 16330119 -- "A simple technique for craniospinal radiotherapy in the supine position." (Parker WA, Radiother Oncol. 2006 Feb;78(2):217-22. Epub 2005 Dec 5.)
 * Supine position, using CT sim

Thyroid

 * Hypothyroidism is one of the earliest late side effects of craniospinal irradiation (CSI), and second most common (after growth hormone disturbances)
 * Prevalence of hypothyroidism is 40-80% after CSI
 * There is also an increased risk of thyroid cancer, possibly with doses as low as 1 Gy

 * Milan; 2007 (1998-2001) PMID 17601681 -- "Thyroid-stimulating hormone suppression for protection against hypothyroidism due to craniospinal irradiation for childhood medulloblastoma/primitive neuroectodermal tumor." (Massimino M, Int J Radiat Oncol Biol Phys. 2007 Oct 1;69(2):404-10. Epub 2007 Jul 2.)
 * Prospective. 37 children with medulloblastoma/PNET. Thyroid function evaluation pre and post treatment. Given L-thyroxine at suppressive doses q3 days, starting 14 day prior CSI till end of treatment. Median F/U 7 years for alive patients
 * Outcome: 8 children adequate TSH suppression, 17 children not. Hypothyroid-free survival rate: adequate TSH suppression 70% vs. not adequate TSH suppression 20% (SS)
 * Conclusion: TSH suppression had a protective effect during CSI

title: Radiation Oncology/CSI


text:
Radiation Oncology/WBRT

 * Yale; 2007 PMID 17276616 -- "A dosimetric evaluation of conventional helmet field irradiation versus two-field intensity-modulated radiotherapy technique." (Yu JB, Int J Radiat Oncol Biol Phys. 2007 Jun 1;68(2):621-31. Epub 2007 Feb 2.)
 * Comparison of opposed laterals and IMRT for helmet technique. V98 100% vs. 99.5%; Dmax 105% vs. 113%
 * Conclusion: IMRT improves dose homogeneity but clinical implications not yet clear

title: Radiation Oncology/WBRT