Coal mining generates significant adverse environmental impacts. Historically, coal mining has been a very dangerous activity and the list of historical coal mining disasters is a long one. Underground mining hazards include suffocation, gas poisoning, roof collapse and gas explosions.
The term 'OVD' (Optically Variable Device) is used to describe both laser generated hologram images and electron beam generated images. These optically variable devices are created in highly-secure facilities and are at the forefront of overt asset and brand protection programmes.
Copy Mini DVD to DVD. miniDVD is a miniature DVD disc that is approximately 3 inches in diameter. A miniDVD can be played back in DVD players that are tray loaded. Because of it's small size miniDVDs hold a relatively small amount of video in standard definition, typically only 20-30 minutes.