U.S. Patent Nos.7,376,606; 7,440,914; 7,596,522; 7,603,307; 7,640,199; 7,899,743; 7,899,745; 7,899,746; 7,899,747; 7,917,433; 7,921,057; 8,036,986; 8,051,004; 8,051,005; 8,190,520; 8,234,188; 8,392,304; 8,527,409; 8,712,881; 8,744,942.

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