1.   Because satellite signals cannot be blocked by political borders, though, the signals continue to be transmitted into Canada.

2.   Bisphosphonates appear to work by blocking these signals, thus reducing metastases.

3.   After all, GPS signals can be blocked in dense forests and jungles.

4.   Buildings and trees block the signals, so their source has to be almost directly overhead, everywhere on earth to ensure high-quality Internet and video transmission.

5.   But in people with asthma, the signal is somehow blocked, and the airways remain constricted.

6.   Dense forest, ravines and other terrain obstructions will block the signals.

7.   For one thing, the GPS satellite signals are often blocked when offenders are inside buildings or outside in areas with many tall buildings.

8.   In an exquisitely clear-cut experiment, Dr. Hongyan Zou and Dr. Lee Niswander blocked the signal and found that chickens developed duck feet.

9.   In an exquisitely clear-cut experi- ment, Dr. Hongyan Zou and Dr. Lee Niswander blocked the signal and found that chickens developed duck feet.

10.   In response, he occasionally taped a metal bucket over the satellite dish on the back of his tractor to block the signal.