The United States unveiled Tuesday its official mascot for next year's World Expo in the Japanese city of Osaka, with officials saying it represents "imagination and innovation."The star-shaped pavilion mascot is named Spark and its design is inspired by American symbols and motifs, such as the national flag's stars and stripes.At an event to preview the U.S. pavilion, Deputy Secretary of State Kurt Campbell said the exposition, which will be held from April to October, will provide "tremendous opportunities for us to engage a broad group of people, not just Japanese friends but visitors fr…READ FULL ARTICLE