The youngest Jonas Brother takes a b-day walk with his pup in Toluca Lake, Calif. Plus: Britney Spears, Gwyneth Paltrow, Lindsay Lohan and more

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HAVE A HEART

Mischa Barton – who recently split with rocker beau Taylor Locke – keeps her spirits up (and her heart in her hands) Monday at the Temperley London runway show during London Fashion Week.