Sacha Langton-Gilks is involved in the HeadSmart campaign which aims to raise awareness of the symptoms of brain tumours in children and young people.
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A police spokesman said the incident in the Bourke Street Mall on Friday was not related to terrorism.
The former reality TV star will follow in the footsteps of Abraham Lincoln and John F Kennedy when he takes his oath later on Friday.
The President-elect's comments on Twitter will come under even closer scrutiny when he takes office on Friday.