The scientific definition of hardness is the ability to resist scratching, nothing more. If you ask most folks, theyâll say feathers are soft and glass is hard. In the world of gemology, however, glass is fairly soft. It can be scratched easily by a variety of what we gemologists consider hard substances.
convergence excess. Convergence excess is an over-convergence of the eyes at a near distance for extended periods of time, such as when reading, writing, drawing, or viewing a computer screen. Sometimes, the over-convergence can result in diplopia (double vision).nce a diagnosis of convergence insufficiency has been made, a simple visual therapy technique that may be helpful is pencil pushups. 1. Hold a pencil at arm s length, with the eraser about level with the tip of your nose.
Speed has been identified as a key risk factor in. road traffic injuries, influencing both the risk of. a road crash as well as the severity of the inju-. ries that result from crashes. Excess speed is defined as exceeding the speed. limit. Inappropriate speed is defined as driving. at a speed unsuitable for the prevailing road. and traffic conditions. Excess and inappropriate. speed are responsible for a high proportion of. the mortality and morbidity that result from. road crashes.