Learn node: Traversing the Suez Canal


Posted on 15th January 2008 by Judy Breck in engineering | geography | history

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The Suez Canal, featured in this learn node, is an enormous topic spanning the globe in influence, and with a story that continues over several millennia. This learnode contains 3 sources that individually and together provide a general overview and lead into other materials so you can traverse this rich subject for yourself.

The postcard that forms the title illustration, “Port Said, Steamer Traversing the Suez Canal,” is from the TIMEA collection. The postcard is displayed on a Rice Connexions unit about Places in Egypt: Lower Egypt, which gives this historical background:

Linking the Mediterranean and the Red Sea, this feat of engineering opened in 1869. Although not the first canal (earlier ones, though not exactly in the same location as the modern one, include ones built by Darius I and Trajan), the modern canal stretches over a hundred miles, from Port Said on the Mediterranean to Suez and the Red Sea. Its opening was the cause of international celebration and was attended by royalty from all over the world; it was also marked by the opening of the “Old” Cairo Opera House, which has since been demolished.

For general background to this vast subject a good place to begin is the Suez Canal overview at Tour Egypt! Another rich cluster of knowledge and links to more for the Suez Canal is the BBC Key map webpage for the 1956 Suez Crisis.

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Learn Node: Helmets to prevent brain injury 79 AD and 2007 AD


Posted on 27th October 2007 by Judy Breck in design | engineering | health

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football helmet gladiator helmetAs this learn node shows, the recent publicity and concern for concussion injuries in sports provides a demonstration of the way networking online knowledge can produce comparative studies from distant fields. When it comes to helmets, history, sports and brain science form a focused network of ideas from all three fields.

Earlier this month, the National Athletic Trainers Association issued a press release describing their new campaign for sports concussion education. The release explains:

The Centers for Disease Control estimate that 300,000 brain injuries occur in sports each year. Of these reported concussions, an estimated 63,000 occur among high school athletes. Even though these numbers alone suggest that concussions represent a significant public health concern, it is likely that many athletes with concussions fail to report their symptoms to medical personnel.

The New York Times today is carrying the story of a new football helmet being developed by former Harvard quarterback Vin Ferrara. The football helmet in the image above is from an interactive graphic that can now be used freely online because of the NY Times new open content policy.

There is, of course, nothing new about the need to protect the human head from blows. Helmet designers have been scratching their heads for centuries to come up with a better way to prevent battering brains by external blows.

The image of the Roman helmet in the graphic above is a Helmet of a Thracian Gladiator on exhibit at the Louve Museum in Paris, France and on their museum website. In this caption the Louvre curators describe the helmet�where there is, like modern sports helmets, distinctive decoration as well as protective features:

Several examples of highly enveloping helmets of this type have been found at Pompeii. They were part of the equipment used by the most heavily armed gladiators – those from the northeast of Greece, the “Thraces” (Thracians), and those from Gaul, the “mirmillones”. The shell of the helmet is highly rounded, with a broad brim, and has a crest decorated with overlapping plumes and terminating in a griffin’s head. This mythological creature was the companion of Nemesis, the goddess of fate, who was venerated by gladiators (there was often a chapel dedicated to her inside the amphitheater). On the front of the helmet, the silver-plated head of the Gorgon Medusa stands out. On either side of the helmet are plume holders to which feathers were attached. The face and neck of the gladiator were protected by a movable visor made up of four riveted plates, two of them solid, the other two pierced.

One of the marvelous resources for open education are museums. Because textbooks must be brief and general, the helmet of a Thracian Gladiator would not survive the first round of editing battles.

Head injury in the past was invisible. A Thracian helmet designer or doctor would have been unable to look inside the skull to see the brain injury of a gladiator whose head had been struck in battle. But today, we can examine brain injuries inside the brain with methods like Computed Tomography (CT) of the head, which is also to be found among open knowledge resources online.

To venture into the future, how about a look at cloning brains in 3D animation of androids at Tufts University?

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Learn node: Mechanics of stone structures


Posted on 13th September 2007 by Judy Breck in design | engineering | math | mechanics

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arch structure

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.

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Learn node: Materials science: mixture or solution


Posted on 1st September 2007 by Judy Breck in chemistry | engineering | general science

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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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