Posted on 24th November 2008 by Judy Breck in biology | engineering | sciences
dolphin, DPIV, Gray's_paradox
In this learn node the 2008 discovery of how the dolphin kicks with huge power is spotlighted at Rensselaer Polytechnic Institute where the discovery was made. For decades, scientists have puzzled over the sea mammal’s speed, since “Gray’s Paradox” was described, as the Rensselaer website explains:
There was something peculiar about dolphins that stumped prolific British zoologist Sir James Gray in 1936. He had observed the sea mammals swimming at a swift rate of more than 20 miles per hour, but his studies had concluded that the muscles of dolphins simply weren’t strong enough to support those kinds of speeds. The conundrum came to be known as “Gray’s Paradox.”
Timothy Wei, professor and acting dean of Rensselaer’s School of Engineering, has solved Gray’s Paradox using his new state-of-the-art water flow diagnostic technology that measures the force a dolphin generates with its tail. The image above is from a video that captures the action of the dolphin by using Digital Particle Image Velocimetry (DPIV). The dolphin performing in the video is Primo, who is retired from the U.S. Navy.
For background on these subjects, the San Diego Zoo has an excellent online dolphin section and the University of California Irvine School of Biological Sciences explains DPIV in great detail.
Posted on 18th November 2008 by Judy Breck in biology | general science | paleontology | sciences
dinosaur, jurassic, mouth, reptile, teeth, tooth
This learn node features a tiny dinosaur with big canine teeth that the Natural History Museum reports shows for the first time how one of the earliest dinosaurs grew into an adult. The webpage explains:
The turkey-sized reptile called Heterodontosaurus lived around 190 million years ago in the Early Jurassic period and had an unusual combination of molar-like and canine teeth.
Reptiles usually have small same-sized teeth along the length of their mouth but Heterodontosaurus had 2 fang-like canines at the front.
The image posted here is from a video narrated by Dr. Richard Butler, a dinosaur expert at the museum and featured on the page linked above.
For nodes of related learning: An excellent overview article about Anatomy and Physiology of the Reptile Mouth is provided at PetEducation.com. For time frames for the dinosaurs, the big picture can be seen in the Chart of Geological Ages at Connexions.
Posted on 12th November 2008 by Judy Breck in biography | geography | history
archduke_ferdinand, bismarck, germany, internet_archive, world_war_I, yale
The Origins of World War I is a lecture from a Yale University on which this learn node is based. The topic is from the Open Yale course France Since 1871 taught by Professor John Merriman, shown teaching in the image. The 45-minute lecture is offered in transcript, mp3 audio, and Flash or Quicktime video. The course overview explains:
The traditional, diplomatic history of World War I is helpful in understanding how a series of hitherto improbable alliances come to be formed in the early years of the twentieth century. In the case of France and Russia, this involves a significant ideological compromise. Along with the history of imperial machinations, however, World War I should be understood in the context of the popular imagination and the growth of nationalist sentiment in Europe.
A major player in the era that led to World War I was Otto von Bismarck. Internet Archive provides his book online: Bismarck, the man and the statesman; being the reflections and reminiscences of Otto, Prince von Bismarck 1898. His image here is from that books frontispiece. The Encyclopedia of 1848 Revolutions is an online source that of a sort the internet has made possible. Dozens of scholars contribute articles to the encyclopedia about the era from in the causes of World War I percolated. The Assassination of Archduke Franz Ferdinand, a kick-off point in World War I, is described in a report in the WWI Document Archive housed at Brigham Young University.
Posted on 6th November 2008 by Judy Breck in energy | engineering
steam, steam_history, steam_practices, steam_types, turbine
This learn node links out to “The story of steam power [that] stretches from attempts to harness atmospheric pressure in the 1600s to the steam turbines we depend upon today.” (Science Museum Energy Hall, source of the flywheel image above.) A steam industry source, spiraxsarco, provides an excellent steam overview. A US Department of Energy Best Practices page for Steam provides extensive practical information and explains:
Over 45% of all the fuel burned by U.S. manufacturers is consumed to raise steam. Steam is used to heat raw materials and treat semi-finished products. It is also a power source for equipment, as well as for building heat and electricity generation. Many manufacturing facilities can recapture energy through the installation of more efficient steam equipment and processes.
An interesting page on nuclear warfare at Notre Dame Open Courseware includes the mention that military tanks were tried with steam power, but it was the internal combustion engine that made tanks successful.
