adj.made tighter or more stringent

"endured tightened economic controls"

Coping with Thailand's Tightened Visa Regulations
Multi-axial bone screw assembly
Effect of electron correlation on theoretical equilibrium geometries
Evidence of a ventilation-perfusion mismatch during acute unilateral pulmonary artery occlusion in broilers
A new model of bilateral hemispheric ischemia in the unanesthetized rat.
SNOPT: An SQP Algorithm for Large-Scale Constrained Optimization
Image representation using 2D Gabor wavelets
Guarded commands, non-determinacy, and the formal derivation of programs
On the hardness of approximating minimization problems
Some-Long-Run Properties of Geophysical Records