Glacial ice has sealed the gateway to Everest’s summit, keeping hundreds of climbers from reaching the top. “Icefall doctors” are on the case. Dawa Jangbu Sherpa is one of 11 elite doctors who monitor the perilous slopes of Mount Everest. But he isn’t there to address medical emergencies — the mountain itself is his patient. He and a team of other Nepali mountain guides, known as “icefall d... [1545 chars]