A German four-man team bolts to a first place finish at a recent World Cup, with Americans taking silver and bronze. Michaela Rehle/Reuters
Steve Holcomb's USA1 sled teammates prepare for their first run at the 2010 World Cup in St. Moritz, Switzerland, after which the US team was named. Arnd Wiegmann/Reuters
Karl Angerer (front) and Alex Mann of Germany, a bobsled powerhouse, compete in a recent World Cup. During the mile-long run, sleds can reach speeds in excess of 90 m.p.h. Arnd Wiegmann/Reuters
US team members Steven Langton, Charles Berkeley, John Napier, and Christopher Fogt, celebrate a recent third-place finish on the World Cup. They're one of three US teams competing in the four-man bobsled in Vancouver. Uwe Lein/AP
German driver Karl Angerer sits on his helmet after crashing his sled during the first run of the 2009 World Championships in Lake Placid, N.Y. In any given competition, drivers must guide their sleds through 15-20 banked turns at speeds that often surpass 90 m.p.h. Peter Morgan/AP
Three bobsledders prepare for their runs in the four-man World Cup competition in St. Moritz, Switzerland: at German pilot Andre Lange (top), his compatriot Karl Angerer (center), and Russia's pilot Alexandr Zubkov (bottom). St. Moritz has the only non-refrigerated track in the world. Arnd Wiegmann/Reuters
German women Cathleen Martini (front) and Romy Logsch celebrate a recent World Cup victory. Martini is one of three female German drivers ranked in the top seven internationally, making the country one of the most dominant in the world. Michaela Rehle/Reuters
A four-man team takes a fall practice run at the U.S. Olympic Training Center in Lake Placid, N.Y. The U.S. Olympic Bobsled Team will consist of 14 men and 6 women. Alfredo Sosa / The Christian Science Monitor
The German and Canadian two-man bobsled teams celebrate a first-place tie at the World Cup in St. Moritz. Bobsled is timed to the hundredths of a second. Arno Balzarini/AP/Keystone
Preparing bobsleds for a run – whether in training or racing – is a time-consuming process. Then, after each run, the sleds must be transported back up to the start – all for an event that lasts less than a minute. Arnd Wiegmann/Reuters
German women bolt to a first-place finish at the 2010 World Cup in Königssee, Germany. The results of the World Cup competition determine the starting lineup at the 2010 Vancouver Games. Michaela Rehle/Reuters
Kaillie Humphries (l.), the No. 2 ranked driver in the world, celebrates World Cup silver with teammate Heather Moyse of Canada. Joining them are the gold-medal winners Cathleen Martini and Romy Logsch of Germany. Michaela Rehle/Reuters
Syria's largest city is contested by various rebel groups, including anti-US jihadists. A UN envoy is trying to broker a temporary cease-fire so that humanitarian aid can reach civilians.
ByDominique Soguel, Correspondent
The battle for Syria’s largest city is intensifying, as are UN-led diplomatic efforts to arrange a local cease-fire. UN envoy Steffan De Mistura is trying to broker a halt to fighting in Aleppo between an array of Islamist and moderate rebels and the government forces of President Bashar al-Assad. Jihadist extremists also have their sights on the city, which is divided into rebel and regime enclaves.