In the days before elevators, there was no such thing as a penthouse on the top floor. The highest floors of a building had cheaper rents because the stairs were hard to climb.
Caracas, Venezuela, is organized roughly the same way, with many poor neighborhoods climbing up the sides of a mountain valley. Some of the poorest homes are among the most remote, accessible not by any road but by alleyways and long flights of stairs.
As Venezuela's president, Hugo Chavez thought in grandiose terms, and his country's vast oil riches enabled him to act on his vision. But Chavez died before he had to deal with the flaws in his model, and some hard choices await his successor.
Key to Chavez's notion of "21st Century Socialism" was the redistribution of Venezuela's oil earnings. The country's oil reserves — estimated by the Organization of Petroleum Exporting Countries to be the largest in the world — are worth tens of billions of dollars a year in potential revenue.
Scientists reported Wednesday that they had developed a way to measure how much pain people are experiencing by scanning their brains.
The researchers hope the technique will help doctors treat pain better, but the work is also raising concerns about whether the technique might interfere with doctors simply listening to their patients.
Now, when someone is in pain, a doctor has no way to judge its severity except to ask questions, a method that often is inadequate.