U.S. Health Secretary Robert F. Kennedy Jr. is to appear before a congressional committee Thursday, where he is expected to face questions about turmoil at federal health agencies. The U.S. Senate Finance Committee has called Kennedy to a hearing about his plans to — according to Kennedy’s slogan — “Make America Healthy Again.” But the health secretary is expected to face questions about layoffs and planned budget cuts that detractors say is wrecking the nation’s ability to prevent disease.