BBC reports the 2008 discovery by Max Planck Institute scientists, using telescopes in Hawaii and Spain to capture faint light echoes of the original explosion — in effect capturing a fossil imprint of Tycho’s famous supernova. Wikipedia’s excellent article on Tycho’s Supernova for more background. NASA’s dictionary defines supernova and other relevant terms. The Galileo Project has a fine biography of Tycho Brahe. MIT’s open courseware offers instruction on the Plasma Physics that is a major focus for Tycho’s supernova.

The center node takes you to the work of Timothy Wei, professor and acting dean of Rensselaer’s School of Engineering, to see how he has solved Gray’s Paradox using his new state-of-the-art water flow diagnostic technology — Digital Particle Image Velocimetry DPIV — that measures the force a dolphin generates with its tail. Other nodes are about DPIV, how the US Navy trains dolphins (a retired Navy dolphin stars in the Rensselear video), general dolphin information (from the San Diego Zoo), and open courseware from Tufts University School of Veterinary Medicine on marine mammal medicine including care of dolphins, who are cetaceans.

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.

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.

Two contrasting behaviors: The first is steady swimming at slow and intermediate speeds using low amplitude axial undulations (i.e. the side to side displacement of the body is small). The second is burst swimming and escape responses using high amplitude axial undulation. In the escape response, a fish bends into a C-like posture then whips its tail in the opposite direction, accelerating a mass of water behind the fish, which causes the fish to accelerate forward. The key is that body bending is small in steady swimming and large in bursts and escapes. Also, the escape response can be very fast, that is less than 1/10th of a second.

The toadfish is an important fish muscle specimen because it has been found that its swim bladder muscles are the fastest twitching muscles in the vertebrate world. The image by Robert Golder shown here is from an article at the Marine Biological Laboratory on this talented but ugly fish. Several articles at the St. Andrews University website of its Fish Muscle Research Group provide the latest ideas and theories in this important subject for mechanics, anatomy, genetics, and aquaculture.

Early Cambrian arthropod chain gangs this learn node describes are fossilized in chain formation that reveals community behavior. The chain gang 525-million-year-old fossils were found in southern China’s Chengjiang Lagerstatte fossil field. A Science News report of the discovery says that the discovery site is “a treasure trove of fossils often compared to Canada’s Burgess Shale.” The above image from Science News (credit Derek Siviter) shows the that newly discovered species of Early Cambrian arthropod formed sturdy chains of about 20 individuals. In the report:

Nigel Hughes, a paleobiologist from the University of California, Riverside comments that these types of finds provide snapshot scenes of “normal” life.

“Of the millions of fossils, the chances of getting an occurrence where we can determine collective behavior is quite rare,” says coauthor Derek Siveter of the University of Oxford in England. He and his colleagues found 22 complete or partial chains, but only one solitary specimen.

A Brief History of Life on Earth provided at Connexions sets the time frame for these fossils

Comparing the sinuses in some newly studied dinosaur bones from Argentina with bird anatomy, this learn node from the Public Library of Science lets students go online to peer over the shoulders of working scientists. The drawing is from Figure 1 in the article. In their recent work concerning the the anatomical relationships of dinosaurs and birds, the scientists here tell us:

In this paper, we describe a new large-bodied theropod from the Late Cretaceous of Argentina, Aerosteon riocoloradensis gen. et sp. nov., characterized by cranial and postcranial bones that are exceptionally pneumatic. Some of its postcranial bones show pneumatic hollowing that can be linked to intrathoracic air sacs that are directly involved in lung ventilation. As a result of an extraordinary level of pneumatization, as well as the excellent state of preservation of much of the axial column and girdles, Aerosteon helps to constrain hypotheses for the evolution of avian-style respiration.

For background on the general subject, the University of California Museum of Paleontology has an overview article: Are Birds Really Dinosaurs?

galileo spacecraft

Galileo and the Pendulum is a node for learning that is part of a rich cluster and course, The Galileo Project at Connexions. Other sections of the Galileo Project are his biography, family life, the Inquisition, and descriptions of his work on motion, mechanical devices, and the telescope.

Surely the great Galileo Galilei of 14th century Italy would gaze in pride on the achievements of his namesake, the Galileo spacecraft that explored the solar system from 1989-2003.

via: Scout Report

The image above is the Hurricane Ike Interactive Map from NOAA. When you go to the page you can click into the boxes to locate and study satellite photos of damage. StormWatch is part of the work of the Johns Hopkins University/ Applied Physics Laboratory.

Remote sensing imagery and study materials abound on the internet. An excellent cluster of information can be found at the Atmospheric Radiation Measurement (ARM) Program which “is a multi-laboratory, interagency program, and is a key contributor to national and international research efforts related to global climate change. A primary objective of the program is improved scientific understanding of the fundamental physics related to interactions between clouds and radiative feedback processes in the atmosphere. ARM focuses on obtaining continuous field measurements and providing data products that promote the advancement of climate models.”

To learn scientific and technical background for the field MIT offers open couseware on Atmospheric Radiation that is “an introduction to the physics of atmospheric radiation and remote sensing including use of computer codes. Subjects covered include: radiative transfer equation including emission and scattering, spectroscopy, Mie theory, and numerical solutions. We examine the solution of inverse problems in remote sensing of atmospheric temperature and composition.”

A NASA- based Remote Sensing Tutorial provides further introduction to the field.