A Yemeni child receives a polio vaccination during a polio immunization campaign at a health center in Sanaa, on December 16, 2013. A three-day anti-polio immunization campaign to vaccinate more than four million children under five years old against polio began. The World Health Organisation and UNICEF have launched a polio vaccination campaign for 23 million children in the Middle East after 17 cases were discovered in Syria, they announced December 9. (AFP/Getty Images)
Vicki Hollub will become the most influential woman in the oil and gas industry when she takes over as CEO of Occidental Petroleum in May. In a bleak period for the sector, how will the future boss of one of America’s biggest energy firms cope with the challenges ahead?