Winter is descending on Aleppo, Syria’s largest city and the bloodied stage for an urban battle, now running into its sixth month, between rebels and the military of President Bashar al-Assad. As temperatures drop and the weakened government’s artillery thunders on, Aleppo is administered by no one and slipping into disaster. Front-line neighborhoods are rubble. Most of the city’s districts have had no electricity and little water for weeks. All of Aleppo suffers from shortages of oil, food, medicine, doctors and gas.