Sensors can be placed discreetly in a building's entrance or turnstile creating an invisible fence.
Las Vegas
A victim of stalking tells her story and a man's sudden death after his Las Vegas wedding.
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Simon Head
MMA writer
Conor McGregor makes a winning return with a first-round victory over Donald Cerrone at UFC 246 in Las Vegas.
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Simon Head
MMA writer
Former UFC women's bantamweight champion Holly Holm claims a unanimous decision victory over Raquel Pennington at UFC 246.
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Paul Battison
BBC Sport
Everything you need to know about Conor McGregor's return to the octagon against Donald 'Cowboy' Cerrone at UFC 246 in Las Vegas this weekend.
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How to follow all the build-up and the UFC 246 fight night on the BBC, as Conor McGregor faces Donald 'Cowboy' Cerrone.
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Ciaran Varley
BBC Three
As Conor McGregor prepares to fight Donald Cerrone at UFC 246, BBC Sport looks at whether the Irishman is losing popularity with his home fans and whether his notoriety has finally become a turn-off.
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Leo Kelion
Technology desk editor
The products set to cause the biggest stir at this year's giant tech expo in Las Vegas.
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Rory Cellan-Jones
Technology correspondent
A look ahead to 2020's technology trends and some ideas about how to make the internet better.
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Carl Frampton says he twice re-fractured his hand in camp before his unanimous win over Tyler McCreary in Las Vegas on Saturday.
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