An Armatix employee holds a “smart gun” by the company at the Armatix headquarters in Munich May 14, 2014. The gun is implanted with an electronic chip that allows it to be fired only if the shooter is wearing a watch that communicates with it through a radio signal. If the gun is moved more than 10 inches (25 cm) from the watch, it will not fire. A Maryland gun shop owner has dropped his plan to be the first in the United States to sell the so-called “smart gun” after a backlash that included death threats. (Photo by Michael Dalder/Reuters)

A replica model of a Lamborghini Aventador LP 700-4 in Dubai, UAE. This is the world's most expensive model car, made from carbon fibre and covered in a thin layer of pure gold. The 1:8 scale replica Lamborghini Aventador LP 700-4, designed by German engineer Robert Gülpen, is available to buy for £200,000. But amazingly this model – currently on display at the Lamborghini showroom in Dubai – is just a prototype for a solid gold model, which will go up for auction in 2014 with a price tag of £4.6 million. (Photo by Robert Gulpen/Barcroft Media)

Inês Carvalho (C), accompanied by her sister and cousin, is helped by her aunt to dress up at Alfama neighborhood in Lisbon on June 12, 2014. Carvalho, 18, is one of the revelers from the Alfama march and every Saint Anthony's day, Lisbon's protector, she parades with several other typical neighborhoods of the city. (Photo by Patricia De Melo Moreira/AFP Photo)

Elaborately dressed monks costumed as wrathful guardian spirits perform ceremonial dances during the Tenchi Festival on May 25, 2014 in Lo Manthang, Nepal. The Tenchi Festival takes place annually in Lo Manthang, the capital of Upper Mustang and the former Tibetan Kingdom of Lo. Each spring, monks perform ceremonies, rites, and dances during the Tenchi Festival to dispel evils and demons from the former kingdom. (Photo by Taylor Weidman/Getty Images)

Three Boeing 737 fuselages lie on an embankment on the Clark Fork River after a BNSF Railway Co train derailed Thursday near Rivulet, Montana in this picture taken July 4, 2014. A train derailment in Montana this week damaged a shipment of jetliner fuselages and other large parts on its way to Boeing Co factories in Washington state from Spirit Aerosystems, Boeing said on Saturday. (Photo by Kyle Massick/Reuters)

“The scientists behind NASA's $2.5 billion Curiosity rover mission on Mars on Tuesday explained the nature of a tiny, gleaming "flower" embedded in Red Planet rock, and revealed where they'll be using the SUV-sized robot's drill for the first time”. – Alan Boyle via NBCNews.com

Photo: Scientists say that a “Martian flower”, seen here in an image from the Curiosity rover's Mars Hand Lens Imager, is a 2-millimeter-wide grain or pebble that's embedded in the surrounding rock. Another, darker-colored mineral grain can be seen above and to the left. (Photo by NASA)

The vendors show the toy of snake at the Spring Festival Temple Fair for celebrating Chinese Lunar New Year of Snake at the Temple of Earth park on February 9, 2013 in Beijing, China. The Chinese Lunar New Year of Snake also known as the Spring Festival, which is based on the Lunisolar Chinese calendar, is celebrated from the first day of the first month of the lunar year and ends with Lantern Festival on the Fifteenth day. (Photo by Feng Li)

A lightning strikes St Peter's dome at the Vatican on February 11, 2013. Pope Benedict XVI announced today he will resign as leader of the world's 1.1 billion Catholics on February 28 because his age prevented him from carrying out his duties – an unprecedented move in the modern history of the Catholic Church. (Photo by Filippo Monteforte/AFP Photo)