The remarkable properties of light-emitting diodes (LEDs) make them ideal sources for many applications ranging from indicator lights, optical communication systems, and displays to solid-state lighting. In this paper a radiometric approach to realistically model the intensity spatial distribution of encapsulated LEDs is presented. We provide an analytical relationship between the radiated patt...

Tracking the development of cities in emerging economies is difficult with conventional data. This paper shows that nighttime lights can be used as a reliable proxy for economic activity at city level, provided they are first corrected top-coding. The commonly-used satellite images light intensity fail to capture true brightness larger cities. We present stylized model urban luminosity and empi...

PURPOSE To compare the effect of reduced exposure times on the microhardness of resin composites cured with a "second-generation" light-emitting diode (LED) curing light and a quartz-tungsten-halogen (QTH) curing light. METHODS Ten composites were cured with a LED curing light for 50% of the manufacturers" recommended exposure time or a QTH light at the high power setting for 50% of the recom...

Recent innovations in smartphone technology have led to the development of a number of applications for the valid and reliable measurement of physical performance. Smartphone applications offer a number of advantages over laboratory based testing including cost, portability, and absence of postprocessing. However, smartphone applications for the measurement of running speed have not yet been va...