Just a few months later, at the time her account was disabled, the Shepherd University student says she had over 4, 000 friends.

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Professor Jonathan Shepherd, from Cardiff University, said the research showed sharing information costs little, and saves money in the longer term for the NHS and the criminal justice system.

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Marshall Shepherd, climate change expert and professor at the University of Georgia.

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"It allows us to make some firm conclusions, " said Andrew Shepherd, a professor of earth observation at the University of Leeds in England and a lead author of the study.

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Prof Shepherd, who was a surgeon at Cardiff's University Hospital of Wales, started his work in 1996 after realising that a great deal of violence which resulted in hospital treatment was not known to the police because victims did not report it.

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