Dear Dr. Roach: Could you please explain in layman terms the difference between an X-ray, CT scan, MRI and PET scan? — C.D.B. Answer: All four of these tests provide images of the body, which…

ANKARA, Turkey (AP) — U.S. National Security Adviser John Bolton is set to press Turkey for assurances that it won’t attack the Kurdish fighters in Syria, which he said is now a condition for the…