41. Multi-zone security electric fence used alongside a physical barrier . 42. Intellectual property has always depended on both legal and physical barriers to copying, Nesson noted. 43. This is a physical barrier to check infiltration. 44. "People have access to and from the site, but there are physical barriers , " said Bejarano. 45. Physical barriers are only part of the equation.46. The French navy could also use its powerful tugboats as a physical barrier against protest vessels. 47. Card-key controls, added security guards and physical barriers in front of buildings are the main improvements. 48. _Physical barriers that can impede communication among employees. 49. The commission believes fences and other physical barriers should be used only as a last resort. 50. As long as the political and physical barriers persist, he said, prices are likely to remain volatile.
