A hiatal hernia does not cause many symptoms by itself, but when a sliding hernia occurs, the abnormal location of the gastroesophageal (GE) junction above the diaphragm affects its function and stomach contents can reflux into the esophagus.
-You need to work on sentence structuring. For example, when you wrote, The immigration, as a decision maked by a person is an act that occurs, because of some factors especially in the under developed countries and the most importants causes or reasons are mainly social reasons, politic reasons and economic reasons..
For a nation of immigrants and immigration, the United States adjusts its immigration policies only rarely, largely because the politics surrounding immigration can be deeply divisive. As a result, immigration policy has often been increasingly disconnected from the economic and social forces that drive immigration.