A method for coding a motion vector using a 2-dimensional minimum bitrate predicting technique is disclosed. A hand-held portable device is provided which can rapidly read small quantities of selected molecular tags in tissues of fish or other animals in the field. The selector circuit receives the first multiphase clock from the oscillator and outputs a second multiphase clock including a plurality of clock signals. At this time, a non-porous single-crystal Si layer is epitaxial-grown on the porous Si layer. Pieces of frangible material dropped into the hopper are sucked to the venturi where they are blown apart and reduced to powder. A light source control part 16 controls a light source 18 so that a visual brightness level on a screen is equal to a brightness level of the input video signal.