There are two effects that I want to talk about. Facebook Has a Negative Impact on the Concentration of Students, about 70-75 percent of high school students are falling behind in class because they spend many hours on Facebook.Therefore, it leads to lack of time to studying or concentration on school work.tudents watch adult movie on Facebook-As Facebook becomes popular, there are more users uploading a lot of music videos that was over 18. The problem is that on Facebook there are many middle school students around 8-9 years old always playing around, so the chance that they would watch adult videos is very high.
Three companies hold the contracts for towers in the various FAA regions around the U.S. Robinson Aviation employs approximately 600 controllers at 96 towers, Midwest Air Traffic Control has 300 controllers at 55 facilities and Serco Management Services employs 307 controllers at 58 contract towers.
In the United States, the carriers have effectively exited the tower business. Most sold their towers to companies like American Tower (AMT) and Crown Castle. These companies construct, maintain and operate the towers, and lease space to the carriers. Tower operators such as AMT actively seek to lease the same tower to multiple carriers, and this is a key metric of their financial success. A best-in-class tower operator will have 2-3 carrier tenants per tower.