The Rhyming Peg Mnemonic Device Applied to Learning the Mohs Scale of Hardness

NOTE: This is a large file, 55.7mb in size! This article describes the use of the rhyming peg mnemonic device to teach Moh's scale of hardness. The "pegs" consist of a set of words, each rhyming with a number from one to ten, to which the mineral names are linked. The mnemonic drawings are incorporated into a poem. This technique is effective because it is meaningful, helps students organize information, provides many associations, uses the creative thinking skill of visualization of images, and focuses student attention. Educational levels: Graduate or professional

Creativity Skills Applied to Earth Science Education: Examples from K-12 Teachers in a Graduate Creativity Class

NOTE: This is a large file, 10.7 mb in size! This article briefly explores different aspects of creativity, and then examines K-12 teachers' reactions to exercises applied to earth science concepts in a graduate creativity class. Different types of puzzle activities centering on geoscience content include a quiz game based on Odyssey of the Mind spontaneous problems, and other exercises related to embedded words, transformed cliches, remotely associated word sets, and wordsmithing. Teachers used visualization for an imaginary interview with a geoscientist, along with personal analogy of an earth science feature. As a culminating activity, teachers fashioned a geoscience curriculum material with a given set of items. Ideas for applying the activities to geoscience classes at various grade levels are included. Educational levels: Graduate or professional, Graduate or professional

Design of a welded joint for robotic, on-orbit assembly of space trusses

In the future, some spacecraft will be so large that they must be assembled on-orbit. These spacecraft will be used for such tasks as manned missions to Mars or used as orbiting platforms for monitoring the Earth or observing the universe. Some large spacecraft will probably consist of planar truss structures to which will be attached special purpose, self-contained modules. The modules will most likely be taken to orbit fully outfitted and ready for use in heavy-lift launch vehicles. The truss members will also similarly be taken to orbit, but most unassembled. The truss structures will need to be assembled robotically because of the high costs and risks of extra-vehicular activities. Some missions will involve very large loads. To date, very few structures of any kind have been constructed in space. Two relatively simple trusses were assembled in the Space Shuttle bay in late 1985. Here the development of a design of a welded joint for on-orbit, robotic truss assembly is described. Mechanical joints for this application have been considered previously. Welded joints have the advantage of allowing the truss members to carry fluids for active cooling or other purposes. In addition, welded joints can be made more efficient structurally than mechanical joints. Also, welded joints require little maintenance (will not shake loose), and have no slop which would cause the structure to shudder under load reversal. The disadvantages of welded joints are that a more sophisticated assembly robot is required, weld flaws may be difficult to detect on-orbit, the welding process is hazardous, and welding introduces contamination to the environment. In addition, welded joints provide less structural damping than do mechanical joints. Welding on-orbit was first investigated aboard a Soyuz-6 mission in 1969 and then during a Skylab electron beam welding experiment in 1973. A hand held electron beam welding apparatus is currently being prepared for use on the MIR space station. Presently, Marshall Space Flight Center is evaluating processes appropriate for on-orbit welding. A low gravity environment has been found to have very minor effects on the welding processes appropriate for this application. This is based on tests run on-orbit as well as low gravity environments achieved by flying aircraft in parabolic trajectories. It appears that a modified form of gas tungsten arc welding (GTAW) will be most appropriate for welding together structures on-oribt. The process has been modified to work in a vacuum by providing gas to the arc zone by means of a hollow tungsten electrode with special shielding. A commercial tube welding head has been successfully modified for use on-orbit with a gas leakage rate of approximately 2.5 liters/min. To develop as realistic a joint as possible, a specific truss structure was selected on which to base the design. The structure considered was based on the 120 foot diameter aerobrake tetrahedral truss structure. The truss members were assumed to consist of graphite/epoxy tubes. Also, it was assumed that the nodes were constructed of 2219-T87 aluminum alloy. The magnitude of the member load assumed for design purposes was 100 kips

Using Poetry to Teach about Minerals in Earth Science Class

This article describes how a high school earth science teacher and a college education professor team-taught a lesson to ninth graders on using poetry to learn about minerals. The professor, a geologist, shared an electronic slide show of poems she had composed about gem minerals that incorporated physical properties, formation, uses, and other information. After instruction, students researched a mineral of choice and wrote poems that contained facts and a personal reaction to the mineral. Some students reported difficulties in finding words to express their ideas in rhyme, but expressed satifaction in the sense of accomplishment in producing a scientific poem. Educational levels: Graduate or professional

Benthic algae and seagrasses of the Walpole and Nornalup Inlets Marine Park, Western Australia

A survey of the marine plants of the Walpole and Nornalup Inlets Marine Park has recorded 49 species of marine benthic algae and seagrasses, including 15 green algae, 11 brown algae, 18 red algae, 4 seagrasses, and one cyanobacterium, representing a substantial increase on the 14 previously recorded species. Most species are relatively common elements of the south-western Australian marine flora, but several are of taxonomic or biogeographic and ecological interest. Included in this group are: a new species of the green algal genus Codium, the first records of previously unknown reproductive phases in the red algae Mazoyerella australis and Spermothamnion cymosum, and a new distribution record for Ossiella pacifica, a species hitherto known only from warmer waters of the Pacific Ocean and not recorded for mainland Australia. The species diversity in the inlets decreases markedly with increasing distance from the ocean, reflecting a reducing marine and increasing estuarine influence

An efficient frequency response solution for nonproportionally damped systems

A method is presented to accurately and economically calculate steady state frequency responses based on the analysis of large finite element models with nonproportional damping effects. The new method is a hybrid of the traditional nonproportional and proportional damping solution methods. It captures the advantages of each computational approach without the burden of their respective shortcomings, as demonstrated with comparative analysis performed on a large finite element model

The Twenty-Fifth Amendment to the United States Constitution: A Reader\u27s Guide

Historic overview and analysis of presidential succession coupled with findings of the law clinic

Charge-equilibrium and radiation of low-energy cosmic rays passing through interstellar medium

The charge equilibrium and radiation of an oxygen and an iron beam in the MeV per nucleon energy range, representing a typical beam of low-energy cosmic rays passing through the interstellar medium, is considered. Electron loss of the beam has been taken into account by means of the First Born approximation allowing for the target atom to remain unexcited, or to be excited to all possible states. Electron capture cross sections have been calculated by means of the scaled Oppenheimer-Brinkman-Kramers approximation, taking into account all atomic shells of the target atoms. Radiation of the beam due to electron capture into the excited states of the ion, collisional excitation and collisional inner-shell ionization of the ions has been considered. Effective X-ray production cross sections and multiplicities for the most energetic X-ray lines emitted by the Fe and O beams have been calculated