WASHINGTON -- At least a half-dozen top NFL health officials waged an improper, behind-the-scenes campaign last year to influence a major U.S. government research study on football and brain disease, congressional investigators have concluded in a new report.

A new congressional report uses Purdue University as an example to push for tighter limits on Chinese students and academic partnerships nationwide, even as it praises the school as a model for research security. The report follows a March inquiry from the ...