One night a young woman in tight jeans rode on the back of a motorbike in southern Khartoum, her hair flowing — a once unthinkable sight, likely to invite arrest.

Now, men in a passing car tooted their horn and made thumbs-up signs. The woman smiled and flashed a victory sign.

“The changes were shocking at first,” said Zuhayra Mohamed, 28, a project manager who defied her parents to participate in the protests. “It’s as if the regime had its arms around our necks for so long, and now there’s something so beautiful.”

But while the old Sudan may be out of sight, it has not gone away.

On a recent morning, dozens of uniformed public order police sat drinking tea under a cluster of trees outside their brightly painted Khartoum headquarters, near the confluence of the Blue Nile and White Nile. They were awaiting orders, a commander said.

And as the protesters celebrated last week, Amer Yousif was being lashed.

The 35-year-old driver had been caught with a bottle of araqi in his pocket on a trip out to buy cigarettes. The next morning a judge sentenced him to 50 lashes, including an extra 10 for aggravated circumstances.

The judge “seemed angered by the revolution,” said Mr. Yousif, lifting his shirt to show a welt on his back.