By Henriette Chacar and Ali Kucukgocmen KAHRAMANMARAS/ANTAKYA, Turkey (Reuters) -Rescuers in Turkey pulled several children alive from collapsed buildings on Monday, a week after the country s worst earthquake in modern history, but hopes of many more survivors were fading and criticism of the authorities grew. In one city, rescuers were digging a tunnel to reach a grandmother, mother and daughter, all from one family, who appeared to have survived the 7.8 magnitude Feb. 6 quake and aftershock that have killed more than 37,000 in Turkey and Syria. But others were bracing for the inevitable scaling down of operations as low temperatures reduced the already slim chances of survival with some Polish rescuers announcing they would leave on Wednesday. In the shattered Syrian city of Aleppo, U.N. aid chief Martin Griffiths said the rescue phase was coming to a close , with the focus switching to shelter, food and schooling. In a sign of hope, a 13-year-old was pulled out alive after spending