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..
Illegal immigration. Illegal immigration is the illegal entry of a person or a group of persons across a country's border, in a way that violates the immigration laws of the destination country, with the intention to remain in the country. Illegal immigration, as well as immigration in general, is overwhelmingly upward, from a poorer to a richer country.