Posted on 28th September 2007 by Judy Breck in general science | sciences
astronomy, orbit, satellite, space, sputnik
This learn node notes the fiftieth anniversary of satellites. On October 4, 1957, the Soviet Union launched a 23-inch diameter satellite. It was the first object ever launched into Earth orbit by humankind, as a post I wrote for iCommons.org describes in a birthday salute to this object named Sputnik 1.
Although the image above suggests Sputnik satellite in orbit, it is more general. It is from a Connexions tutorial � an open educational resource where you can learn how artificial satellites are the backbone of modern communications system. A lot has happened in the past 50 years as orbiting objects have diversified and become common. The open learning website How Stuff Works’ section on How Satellites Work begins:
Not so long ago, satellites were exotic, top-secret devices. They were used primarily in a military capacity, for activities such as navigation and espionage. Now they are an essential part of our daily lives. We see and recognize their use in weather reports, television transmission by DIRECTV and the DISH Network, and everyday telephone calls. In many other instances, satellites play a background role that escapes our notice.
An interesting place to move out into the online clusters of the adventures and ramifications of the Sputniks is from this Astronomy Picture of the Day salute to Traveling Companion (which is what “sputnik” means). You can even meet Laika, the first dog in space.
More learn nodes at: learnodes.com
Posted on 21st September 2007 by Judy Breck in math
circle, geometry, math, mathematics
This learn node looks first in the new issue of the math and arithmetic online magazine plus where this month an article titled What is the area of a circle? uses cake slices to illustrate some principles of the geometry of a circle. The author of the circle studies is Tom Ko�ner, a lecturer in the Department of Pure Mathematical Statistics at Cambridge University. The magazine brings math explanations from terrific teachers to online visitors. The circle at the right was the work of a student in an MIT class on Geometric Combinatorics. The right circle and formulas to explain it are on page 7 of the PDF called “Bounds of Crossing Numbers.”
Two stand-bys of open learning for math show up at the top of a Google search for “geometry circles.’” One is the colorful Cool Math that been nurtured for a decade, with some advertising support. The other is a Geometry Circles from Math for Morons Like Us, created by the ThinkQuest team in 1998. For more circle investigations, go to University of Birmingham Lecturer Chris Sangwin’s geoGebra page.
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Posted on 19th September 2007 by Judy Breck in biography | history
biography, churchill, england, history, iron_curtain
An iron curtain has descended across the continent.
The speech in which Winston Churchill used those words and gave the phrase “iron curtain” to the 20th century Cold War era was given in Fulton, Missouri on March 5, 1946. A few of the sentences from the speech, including the words above and Sir Winston’s enunciation of the “capitals of the ancient states” behind the curtain can be accessed in Churchill’s voice from the Library of Congress. This audio node is included in a major exhibition by the LOC and Annenberg Foundation titled Churchill and the Great Republic. The exhibition networks photographs, texts, sounds and commentary into a distinguished digital biography of Churchill. (For a look at some realities of the Cold War that the Iron Curtain brought on: The Berlin Airlift.)
The Internet has many superb Churchillian nodes, which when interlinked form a web of Sir Winston’s rich weave into the fabric of 20th century history and thought. The grand appreciation for him is expressed in a BBC archived exhibit of his state funeral. To catch something of the vigor and courage of this great man, the Churchill Center’s page of quotations is a good place to start. For example, Churchill told the United States Congress in 1941:
“I am a child of the House of Commons. I was brought up in my father’s house to believe in democracy. ‘Trust the people’ that was his message….I owe my advancement entirely to the House of Commons, whose servant I am. In my country, as in yours, public men are proud to be the servants of the State and would be ashamed to be its masters. Therefore I have been in full harmony all my life with the tides which have flowed on both sides of the Atlantic against privilege and monopoly….By the way, I cannot help reflecting that if my father had been American and my mother British, instead of the other way around, I might have got here on my own!”
Posted on 13th September 2007 by Judy Breck in design | engineering | math | mechanics
arches, math, mathematics, mechanics
This learn node features a video called “The Arch Never Sleeps” in which professors explain the mechanics of the support arches provide for structures. One professor points out the limitations of laying a block of stone across two others. The professor whose foot is shown as he stands on an arch (that is not glued together) is demonstrating the strength of stone arches. The video is on a page from the Open University Mathematics and Statistics modeling problems open courseware.
If the concepts of arches and mechanical forces get curiosity strongly aroused, a popular online set of notes for the mathematics of mechanics can be found at the University of Nebraska-Lincoln. Included are algebra, geometry, trigonometry, analytical geometry, calculus and vectors � as each of them relates to mechanics. Or for more concrete contemplations of arches mathematics and more, there is a page titled Geometry of Bridge Construction by a Jesuit teacher of math. That site includes a quick explanation of the famed seven Bridges of Konigsberg problem and Euler’s solution that provides a key basis for understanding how the connectivity of the Internet makes it possible for learn nodes to form the webs from which ideas can emerge. Related in time and math concepts are the Medieval breakthroughs in math visible in mosaics from Islamic buildings.
More learn nodes at: learnodes.com
Posted on 10th September 2007 by Judy Breck in math
algebra, math, mathematics, motion
This learn node cluster math help available online virtually from an amazing array of open sources. The picture here of Wolfgang Pauli and Niels Bohr as they “stare in wonder at a spinning top” is from lectures by David Tong of Cambridge University on Classical Dynamics. The picture is included in the third Tong lecture titled The Motion of Rigid Bodies. Pauli and Bohr � great mathematicians of the early 20th century � would surely turn the full intensity of their wonder on how a click of a 21st century mouse sends students to math help, math problems and math mentors.
In a click or two this learn node crosses the Atlantic pond from Cambridge to MIT for Algebra I lectures or to a place to think about geometry themes and variations while listening to some Bach.
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Posted on 3rd September 2007 by Judy Breck in biology | health | molecules, cells
cells, polio, poliomyelitis, virus
Polio invasion is seen in this learn node illustration. The little purple ball – lower center in this image – is a very scary thing. It is polio entering a person’s gut. Good public health can prevent polio and many other human miseries. Superb learning materials for public health practitioners are available as open education resources OER at Johns Hopkins Bloomberg School of Public Health. The image above combines slides 26-28 from an OPENCOURSEWARE course on Public Health Biology. The exact location for these OER lectures, which are open for you to download, is: Module 2: Pathogens and Host Immunity > Lecture 3: Pathogens: Nature and Transmission. This is the text that accompanies the illustrations above:
Poliovirus Viron (left image):
30 nM diameter virion contains 60 copies each of four proteins (encoded in the viral RNA) – Viral RNA is a single strand mRNA (+) polarityi, is about 8000 bases long, and encodes 11 proteins – Viron is non-enveloped and contains no enzymes
Poliovirus: Intracellular Replication (right image):
1. Attachment to cell via specific receptor (Vpr) on cell membrane 2. Virus entry (endocytosis); extrusion of RNA into cytoplasm 3-5. Translation of viral RNA; processing of polyprotein; formation of RNA replicase protein 8-10. Replication of viral RNA 11. Continued translation and processing; formation of virion proteins 12. Assembly of (+) RNA and rivon proteins into new virions 13. Virion release into the gut
MORE POLIOVIRUS LEARN NODES:
For more about the ongoing fight against polio, the Stony Brook University School of Medicine published an open access article in Virology Journal: “Epidemics to eradication: the modern history of poliomyelitis.”
For a look at sleuths who are tracking the polio viruses as they invade our cells try this open access article from the Public Library of Science BIOLOGY: “Imaging Poliovirus Entry in Live Cells.”
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Posted on 1st September 2007 by Judy Breck in chemistry | engineering | general science
chemistry, materials, mixture, science, solution
The sketch in this learn node is from a course taught at MIT. You can virtually sit in on the lectures from the course by clicking this link: Fundamental Concepts of Material Science. The above sketch is from page 7 of lecture L2 PDF that you can download from the list you will get when you click the link. The sketch teaches us:
Mixture: Inhomogeneous multi-phase system where the components are not mixed on a molecular level.
Solution: Homogeneous system, components are mixed on a molecular level.
The difference between a solution and a mixture is a basic idea that the illustration above gives us � so that we can go on in our own learning to other concepts linked to the subject. The PDF of the lecture is an excellent place to move on in this learning; it has 13 pages of basics. The elemental new power of learning in the network ecology online is a matter of grasping a node like this one about “mixture or solution” and linking to related nodes to build concepts and experience thinking.
MORE LEARN NODES about mixtures and solutions from Rice University: “The word mixture can be defined as a heterogeneous association of substances that cannot be represented by a single chemical formula. This definition does not limit mixtures to solids mixed with liquids, nor is every mixture considered to be a solution. . . .”
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