Category: Uncategorized

Red Giants And White Dwarfs
Red giants and white dwarfs come about because stars, like people, change with age and eventually die. For people, the cause of aging is the deterioration of biological functions. For a star, the cause is the inevitable energy crisis as it begins to run out of nuclear fuel.

Since its birth 4.5 billion years ago, the Sun’s luminosity has very gently increased by about 30%.3 This is an inevitable evolution which comes about because, as the billions of years roll by, the Sun is burning up the hydrogen in its core. The helium “ashes” left behind are denser than hydrogen, so the hydrogen/helium mix in the Sun’s core is very slowly becoming denser, thus raising the pressure. This causes the nuclear reactions to run a little hotter. The Sun brightens.

This brightening process moves along very slowly at first, when there is still ample hydrogen remaining to be burnt at the center of the star. But eventually, the core becomes so severely depleted of fuel that its energy production starts to fall regardless of the increasing density. When this happens, the density of the core begins to increase even more, because without a heat source to help it resist gravity, the only possible way the core can respond is by contracting until its internal pressure is high enough to hold up the weight of the entire star. Bizarrely, this emptying of the central fuel tank makes the star brighter, not dimmer, because the intense pressure at the surface of the core causes the hydrogen there to burn even faster. This more than takes up the slack from the fuel-exhausted center. The star’s brightening not only continues, it accelerates.

guitar playing. Because the new strings are much stronger. require less frequent tuning and produce better sound, they are more practical and more desirable. At present, the internationalization of the guitar is complete. The instrument is taugh throughout the world. After World War II, the guitar became incredibly popular in Japan and the country has produced a great number of guitarists, teachers and guitar makers. Almost everywhere magazines dealing with the guitar are published and available. International journals on guitar now exist and prints articles on guitar activities throughout the world: The Classical Guitar Magazine, published in England, and The Guitar Review, published in New York, have a worldwide circulation and are also published on Internet. Guitar Societies have grown everywhere. The burgeoning of societies, associations and organizations devoted to some facet or other of guitar activities bears further witness to the universal interest in the instrument. These organizations present young guitarists in recitals, encourage study, dedicate themselves to a great variety of aims having to do with the propagation of matters pertinent to the guitar. Number of guitar recitals have multiplied as competitions held on both national and international levels. REFERENCES Grunfeld, Frederic V.: “The Art and Times of the Guitar”, Collier MacMillan Publishers, London 1969. Sparks, Paul: “Guitar performance in the nineteenth and twentieth centuries”, Performance Practice Review Vol.10 No.1, 1997,: 71-79. Tyler James: “The guitar and its performance from the fifteenth to eighteenth centuries”, Performance Practice Review Vol.10 No.1, 1997,: 61-70. Bacon, Tony and Day, Paul: “The Ultimate Guitar Book”, Dorling Kindersley Limited, London 1991. “What is a Harp Guitar: http://www.harpguitars.net/history/org/hgorg.htm “Organology: HarpGuitar “Relatives”http://www.harpguitars.net/history/org/orgfretted_hgs.htm “The Guitar Foundation of America : http://www.guitarfoundation.org/

Maximum Strength of Materials
Figure 5

Contents

• From Nothing, to Monumental, to Agile
• Predictive versus Adaptive
  • Separation of Design and Construction
  • The Unpredictability of Requirements
  • Is Predictability Impossible?
  • Controlling an Unpredictable Process – Iterations
  • The Adaptive Customer
• Putting People First
  • Plug-Compatible Programming Units
  • Programmers are Responsible Professionals
  • Managing a People Oriented Process
  • The Difficulty of Measurement
  • The Role of Business Leadership
• The Self-Adaptive Process
• Flavors of Agile Development
  • Agile Manifesto
  • XP (Extreme Programming)
  • Scrum
  • Crystal
  • Context Driven Testing
  • Lean Development
  • (Rational) Unified Process
• Should you go agile?

• (Email me with your story, you might get to be mentioned here… 🙂 —- Update: I like to hear what happened to you. This will allow me to guess what happens most, and keep this file as accurate as possible. However I now have around 500 different Email addresses of people who’ve had sig-11 problems. I don’t think that it is useful to keep on adding “random” people’s names on this list. What do YOU think?

---

I’m interested in new stories. If you have a problem and are unsure about what it is, it may help to contact me. My curiosity will usually drive me to answering your questions until you find what the problem is….. (on the other hand, I do get pissed when your problem is clearly described above 🙂

Friedrich Bessel	1784-1846 Prussian	first to measure distance to the star 61 Cygni; proposed that Sirius has an unseen companion; worked out the mathematical analysis of what are now known as Bessel functions
Joseph von Fraunhofer	1787-1826 German	made detailed wavelength measurements of hundreds of lines in the solar spectrum; designed an achromatic objective lens
Johann Franz Encke	1791-1865 German	discovered the first short-period comet, now called Encke’s comet
Friedrich von Struve	1793-1864 German-born Russian	founded the study of double stars; published catalog of over 3000 binary stars; first to measure distance to the star Vega
Wilhelm Beer	1797-1850 German	prepared and published maps of the Moon and Mars
Thomas Henderson	1798-1844 Scottish	first to measure distance to a star (Alpha Centauri)
William Lassell	1799-1880 British	discovered Triton, the largest satellite of Neptune
Sir George Airy	1801-1892 British	improved orbital theory of Venus and the Moon; studied interference fringes in optics; made a mathematical study of the rainbow
Urbain Le Verrier	1811-1877 French	accurately predicted the position of Neptune, which led to its discovery
Johann Gottfried Galle	1812-1910 German	first person to observe Neptune, based on calculations by French mathematician, Urbain Le Verrier; however, Neptune’s discovery is usually credited to Le Verrier and English astronomer, John Crouch Adams, who first predicted its position
Anders Ångström	1814-1874 Swedish	discovered hydrogen in the solar spectrum; source of the Angstrom unit
Daniel Kirkwood	1814-1895 American	discovered the “Kirkwood gaps” in the orbits of the asteroids between Mars and Jupiter; explained the gaps in Saturn’s rings
William Huggins	1824-1910 British	first to show that some nebulae, including the great nebula in Orion, have pure emission spectra and thus must be gaseous
Sir Joseph Lockyer	1836-1920 British	discovered in the solar spectrum a previously unknown element that he named helium
Henry Draper	1837-1882 American	made first photograph of a stellar spectrum (that of Vega); later photographed spectra of over a hundred stars and published them in a catalog; studied spectrum of Orion Nebula, which he showed was a dust cloud
Edward Charles Pickering	1846-1919 American	discovered the first spectroscopic binary star, Mizar
Jacobus Cornelius Kapteyn	1851-1922 Dutch	discovered that the proper motions of stars were not random, but stars could be divided into two streams moving in opposite directions, representing the rotation of our galaxy
Edward Barnard	1857-1923 American	discovered eight comets and Almathea, the fifth moon of Jupiter; also discovered star with largest proper motion, now called Barnard’s star

Voice:

• Use active constructions. For example, say “the operating system starts the device” instead of “the device is started by the operating system.”

 

Tense:

Write in the present tense. For example, say “The system writes a page to the disk and then uses the frame…” instead of “The system will use the frame after it wrote the page to disk…”

Define Negation Early:

Example: say “no data block waits on the output queue” instead of “a data block awaiting output is not on the queue.”

Grammar And Logic:

• Be careful that the subject of each sentence really does what the verb says it does. Saying “Programs must make procedure calls using the X instruction” is not the same as saying “Programs must use the X instruction when they call a procedure.” In fact, the first is patently false! Another example: “RPC requires programs to transmit large packets” is not the same as “RPC requires a mechanism that allows programs to transmit large packets.”

All computer scientists should know the rules of logic. Unfortunately the rules are more difficult to follow when the language of discourse is English instead of mathematical symbols. For example, the sentence “There is a compiler that translates the N languages by…” means a single compiler exists that handles all the languages, while the sentence “For each of the N languages, there is a compiler that translates…” means that there may be 1 compiler, 2 compilers, or N compilers. When written using mathematical symbols, the difference are obvious because “for all” and “there exists” are reversed.

Focus On Results And Not The People/Circumstances In Which They Were Obtained:

• “After working eight hours in the lab that night, we realized…” has no place in the dissertation. It doesn’t matter when you realized it or how long you worked to obtain the answer. Another example: “Jim and I arrived at the numbers shown in Table 3 by measuring…” Put an acknowledgement to Jim in the dissertation, but do not include names (even your own) in the main body. You may be tempted to document a long series of experiments that produced nothing or a coincidence that resulted in success. Avoid it completely. In particular, do not document seemingly mystical influences (e.g., “if that cat had not crawled through the hole in the floor, we might not have discovered the power supply error indicator on the network bridge”). Never attribute such events to mystical causes or imply that strange forces may have affected your results. Summary: stick to the plain facts. Describe the results without dwelling on your reactions or events that helped you achieve them.

 

Avoid Self-Assessment (both praise and criticism):

Both of the following examples are incorrect: “The method outlined in Section 2 represents a major breakthrough in the design of distributed systems because…” “Although the technique in the next section is not earthshaking,…”

References To Extant Work:

• One always cites papers, not authors. Thus, one uses a singular verb to refer to a paper even though it has multiple authors. For example “Johnson and Smith [J&S90] reports that…”

Avoid the phrase “the authors claim that X”. The use of “claim” casts doubt on “X” because it references the authors’ thoughts instead of the facts. If you agree “X” is correct, simply state “X” followed by a reference. If one absolutely must reference a paper instead of a result, say “the paper states that…” or “Johnson and Smith [J&S 90] presents evidence that…”.

 

Terms And Phrases To Avoid:

• adverbs
  Mostly, they are very often overly used. Use strong words instead. For example, one could say, “Writers abuse adverbs.”
• jokes or puns
  They have no place in a formal document.
• “bad”, “good”, “nice”, “terrible”, “stupid”
  A scientific dissertation does not make moral judgements. Use “incorrect/correct” to refer to factual correctness or errors. Use precise words or phrases to assess quality (e.g., “method A requires less computation than method B”). In general, one should avoid all qualitative judgements.
• “true”, “pure”,
  In the sense of “good” (it is judgemental).
• “perfect”
  Nothing is.
• “an ideal solution”
  You’re judging again.
• “today”, “modern times”
  Today is tomorrow’s yesterday.
• “soon”
  How soon? Later tonight? Next decade?
• “we were surprised to learn…”
  Even if you were, so what?
• “seems”, “seemingly”,
  It doesn’t matter how something appears;
• “would seem to show”
  all that matters are the facts.
• “in terms of”
  usually vague
• “based on”, “X-based”, “as the basis of”
  careful; can be vague
• “different”
  Does not mean “various”; different than what?
• “in light of”
  colloquial
• “lots of”
  vague & colloquial
• “kind of”
  vague & colloquial
• “type of”
  vague & colloquial
• “something like”
  vague & colloquial
• “just about”
  vague & colloquial
• “number of”
  vague; do you mean “some”, “many”, or “most”? A quantative statement is preferable.
• “due to”
  colloquial
• “probably”
  only if you know the statistical probability (if you do, state it quantatively
• “obviously, clearly”
  be careful: obvious/clear to everyone?
• “simple”
  Can have a negative connotation, as in “simpleton”
• “along with”
  Just use “with”
• “actually, really”
  define terms precisely to eliminate the need to clarify
• “the fact that”
  makes it a meta-sentence; rephrase
• “this”, “that”
  • As in “This causes concern.” Reason: “this” can refer to the subject of the previous sentence, the entire previous sentence, the entire previous paragraph, the entire previous section, etc. More important, it can be interpreted in the concrete sense or in the meta-sense. For example, in:

  “X does Y. This means …”

   the reader can assume “this” refers to Y or to the fact that X does it. Even when restricted (e.g., “this computation…”), the phrase is weak and often ambiguous.
• “You will read about…”
  The second person has no place in a formal dissertation.
• “I will describe…”
  The first person has no place in a formal dissertation. If self-reference is essential, phrase it as “Section 10 describes…”
• “we” as in “we see that”
  A trap to avoid. Reason: almost any sentence can be written to begin with “we” because “we” can refer to: the reader and author, the author and advisor, the author and research team, experimental computer scientists, the entire computer science community, the science community, or some other unspecified group.
• “Hopefully, the program…”
  Computer programs don’t hope, not unless they implement AI systems. By the way, if you are writing an AI thesis, talk to someone else: AI people have their own system of rules.
• “…a famous researcher…”
  It doesn’t matter who said it or who did it. In fact, such statements prejudice the reader.
• Be Careful When Using “few, most, all, any, every”.
  A dissertation is precise. If a sentence says “Most computer systems contain X”, you must be able to defend it. Are you sure you really know the facts? How many computers were built and sold yesterday?
• “must”, “always”
  Absolutely?
• “should”
  Who says so?
• “proof”, “prove”
  Would a mathematician agree that it’s a proof?
• “show”
  Used in the sense of “prove”. To “show” something, you need to provide a formal proof.
• “can/may”
  Your mother probably told you the difference.

In Italy the first great center of the paper-making industry was Fabriano in the marquisate of Ancona. Mills were established in 1276, and rose to importance with the decline of the manufacture in Spain. (http://www.manufactura.cz/paper.htm)The first official document recording the presence of paper manufacturing in Fabriano dates to 1283, and is the deed of a public notary recording the purchase of a house by a “carthaio” or paper maker, with another six paper makers called as witnesses. This document clearly points to the existence of a number of paper factories, and implies a well developed commercial activity.
Fabriano was the first manufacturing center to harness water power to drive the fibrillation (pulping) process, previously a labor intensive manual activity. (http://www.museodellacarta.com/ing/chiavelli.html)

In 1340 a factory was established at and Treviso ; and other factories were quickly established in the territories of Florence, Bologna, Parma, Milan, Venice. The factories of northern Italy supplied southern Germany with paper as late as the 15th century. The earliest German factories are said to have been set up between Cologne and Mainz, and in Mainz itself about 1320. Ulman Stromer established a mill in 1390 at Nuremberg, with the aid of Italian workmen. Ratisbon and Augsburg were other sites of early manufacture. Western Germany, the Netherlands and England, are said to have obtained paper at first from France and Burgundy then through the markets of Bruges, Antwerp and Cologne.
The first paper-mills in France were established in 1189, in the district of Hérault. By the second half of the 14th Century, the use of paper for all literary purposes had become established in all of Western Europe. In the course of the 15th century vellum was gradually superseded by paper. Some later manuscripts would use a mixture of vellum and paper. usually a vellum sheet would form the outer, or the outer and inner, leaves of a quire while the rest were paper.
(Stutermeister 1954, 11) Paper Making In Italy