Parents in Philadelphia need to make sure their children aren’t out past 9 p.m. this weekend in Center City or University City. Earlier this week, Mayor Michael Nutter announced the city was temporarily tightening its weekend curfew in parts of the city for those under 18 years old. Police will be out in full force to keep the peace.Police Commissioner Charles Ramsey said there will be a strong police presence in the city on weekends for as long as it’s needed. And he says that means paying officers overtime. “Last weekend that was about $56,000 for both days–for Friday and Saturday–for the overtime,” said Ramsey. “Fifty-six thousand dollars is about what it cost us last weekend and approximately what it will cost this weekend, and every weekend that we put this deployment out.”Ramsey said he won’t put a price on public safety and if it makes people feel safer–and it stops the assaults–it’s well worth the investment.He said the city’s willing to expand the special curfew zone, or impose it 7 days a week, if need be.