Although the Russians and the Chinese are reportedly fretting about the end of the world tomorrow  — according to an interpretation of the ancient Mayan calendar — down here in the Yucatan, which was part of the Mayan empire, the locals couldn’t care less. Nor does anyone in Mexico City seem to notice. They are too busy thinking about what the new government is going to get up to. With its candidate, Enrique Peña Nieto, sworn into as president on Dec. 1, the Institutional Revolutionary Party (PRI) is back in power after 12 years out of office.