Through the 2008 Summer Games, the U.S. has never won a medal in handball, table tennis, rhythmic gymnastics, and badminton. According to the olympic website, the US has 3 events it has never won a medal in----I know one of them is Handball, but do not know the other two. Through the 2006 Winter Games, the U.S. has never won a medal in biathlon and nordic combined.
The circle with the arrow means male, and the circle with the plus sign means female. the circle with a plus-sign is used as the zodiacal symbol for the planet Venus. It is the female and male sign. the one in your question with the top pointing up is male, and the one with the cross pointing down, is female.
The circle symbolizes the sacred earth. However, the square symbolizes the opposite. The meaning of the square is about the physical world. The square had a focus of the points of the compass to the pagans. Like a circle that is split into quarters, the square will indicate north, east, south, and west. The circle could represent traits of the female.