US bakery chain Panera Bread has posted fourth-quarter net income of $7.5m, compared with $4.8m a year earlier. The company, which opened 43 new bakery-cafes and closed one during the quarter, posted revenue of $73m compared with $55.7m in the year-ago period.   Panera, which owns or franchises around 478 bakery-cafes, said first-quarter same-store sales have so far been hurt by unusually cold weather. The company said it expects same-store sales to increase by around 3% for the remainder fo the year.