Mischa Barton came up trumps at the Ronson twins' weekend bash in New York. Barton, whose recent mental health has been a matter of concern, was all smiles and vitality as she attended the shindig for the I (Heart) Ronson clothing line put out by DJ Samantha Ronson and her sister Charlotte. UK television presenter Alexa Chung and actress Hilary Duff were guests for the Chelsea Piers event, while Lindsay Lohan was not. Lohan is Samantha Ronson's on-again, off-again partner. Barton, who jumped straight from psychiatric treatment into work in New York on The Beautiful Life, arrived at the Ronson do with a pal, actress Ashley Madekwe. The pair are co-stars in the Ashton Kutcher-produced story of models trying to make it in New York. Barton's quick return to work had some friends concerned. One said: "It's only been a matter of days since she was released from the hospital, and I think she definitely wasn't there long enough. She needs to be very cautious - she's at a very big risk." But for now Barton appears to be getting by with the help of her friends.