In the world of the American public school, few subjects are more controversial than intelligence. If there’s a tension in American society between the ideal of equality and the pursuit of meritocracy, that tension escalates into the equivalent of a migraine headache in the schools. Called upon to produce young people fully prepared for citizenship and ready to meet the competitive challenges o...

Background: Repeated implantation failure (RIF) is the main problem after using assisted reproductive techniques (ART). The main causes of RIF as a multifactorial problem including decrease in endometrial receptivity, defects of embryo or combinational. Successful embryo implantation depends on trophoblast proliferation, migration and invasion to the endometrium, all of which are associated wit...