Symmetry plays an important role in human reasoning about physical systems. Symmetry has been used as a constraint when deriving models for specific systems (as in dimensional analysis) as well as for physical laws. After reviewing human reasoning by symmetry in physics, this paper formalizes a symmetry-based reasoning. In dimensional analysis, only the scale symmetry for unit of measure of ind...

BACKGROUND Previous research suggests that school characteristics may influence physical activity. However, few studies have examined associations between school building and campus characteristics and objective measures of physical activity among middle school students. METHODS Students from ten middle schools (n=248, 42% female, mean age 13.7 years) wore TriTrac-R3D accelerometers in 1997 r...

In recent years, it has become evident that it is necessary to systematically and accurately define particle characteristics in order to understand the potential toxicity of nanoparticles to biological systems. The properties that need to be emphasized are size, shape, dispersion, doping, aggregation, functionalization, physical and chemical properties, surface area, and surface chemistry. Rout...

 Brain-computer interfaces (BCI) record brain signals, analyze and translate them into control commands which are relayed to output devices that carry out desired actions. These systems do not use normal neuromuscular output pathways. Actually, the principal goal of BCI systems is to provide better life style for physically-challenged people which are suffered from cerebral palsy, amyotrophic l...

Abstract—The plastic industry plays very important role in the economy of any country. It is generally among the leading share of the economy of the country. Since metals and their alloys are very rarely available on the earth. Therefore, to produce plastic products and components, which finds application in many industrial as well as household consumer products is beneficial. Since 50% plastic...