Israeli companies excel in computer software and hardware development, particularly computer security technologies, semiconductors and communications. Israeli firms include Check Point, a leading firewall firm; Amdocs, which makes business and operations support systems for telecoms; Comverse, a voice-mail company; and Mercury Interactive, which measures software performance. A high concentration of high-tech industries in the coastal plain of Israel has led to the nickname Silicon Wadi (lit: "Silicon Valley"). More than 3,850 start-ups have been established in Israel, making it second only to the US in this sector and has the largest number of NASDAQ-listed companies outside North America. Optics, electro-optics, and lasers are significant fields and Israel produces fiber-optics, electro-optic inspection systems for printed circuit boards, thermal imaging night-vision systems, and electro-optics-based robotic manufacturing systems. Research into robotics first began in the late 1970s, has resulted in the production of robots designed to perform a wide variety of computer aided manufacturing tasks, including diamond polishing, welding, packing, and building. Research is also conducted in the application of artificial intelligence to robots.