The parking lot at Durham's Lincoln Community Health Center fills quickly on a weekday morning, as cars, taxis, and shuttle buses jockey for space. Boarded-up houses and junked cars pockmark the surrounding neighborhood, where the poverty rate is clearly much higher than the 15 percent countywide. But inside the center, the mood is upbeat, and the lobby and halls teem with activity. Elderly women talk with young mothers, men swap jokes, and children watch videos and play games as they wait to be seen.