Urchin

Urchin or urcheon is the Middle English term for "hedgehog". As such, it is applied to many things that take a similar form to a hedgehog:

It may also refer to:

Urchin (film)

Urchin is a 2007 film about a homeless boy living in a New York City underground mole people community called Scum-City.

Plot

This is the story of a child who lives in Scum City. When the Old Man came to Scum City, a homeless camp in the Manhattan tunnels, his story seemed wild. He was from a kingdom deep within the earth, he said, and was sent to find the five nobles who got lost up here.

He had a map that would lead him and his followers back to this paradise, and a blue crystal called The Blessing, that when smoked granted the clarity and vision needed to complete great tasks.

Some believed. They were allowed to stay.

The Kid believes. Abused and tormented, he escaped the city shelter and fled to the streets, where he survived by wit and blood until he found Scum City. He will fulfil the Old Man's prophecy; he will get to paradise.

But someone else believes. The Old Man had a bodyguard once, a powerful little man called Goliath whose lungs and mind are rotting away. In his dementia he has committed to the ritual murder of innocents and the capture of the map held fast by the Old Man.

Modulated neutron initiator

A modulated neutron initiator is a neutron source capable of producing a burst of neutrons on activation. It is a crucial part of some nuclear weapons, as its role is to "kick-start" the chain reaction at the optimal moment when the configuration is prompt critical. It is also known as an internal neutron initiator. The initiator is typically placed in the center of the plutonium pit, and is activated by impact of the converging shock wave.

One of the key elements in the proper operation of a nuclear weapon is initiation of the fission chain reaction at the proper time. To obtain a significant nuclear yield, sufficient neutrons must be present within the supercritical core at the right time. If the chain reaction starts too soon ("predetonation"), the result will be only a 'fizzle yield', well below the design specification, therefore low spontaneous neutron emission of the pit material is crucial. If it occurs too late, the core will have begun to expand and disassemble into a less-dense state, leading to a lowered yield (less of the core material undergoes fission) or no yield at all (the core is no longer a critical mass).