A dynamic heat flow meter is provided which introduces a measured air flow into the system adjacent the test sample, for which thermal properties are to be measured. One type of screw addresses the problem of extravazation of bone cement when filling an area of low-quality bone. The frequency passing circuit includes components forming a traditional low-pass or high-pass filter network and a resistive component connected in parallel across the second series mounted component of the low-pass or high-pass filter network. or lower at or below Tg, and the foil of the first layer has thickness greater than thickness of the foil of the second layer. Such a light emitting structure may improve emission characteristics, heat dissipation and high temperature reliability.