Pulmonary embolism. Pulmonary embolism Pulmonary embolism occurs when a blood clot gets lodged in an artery in the lung, blocking blood flow to part of the lung. Blood clots most often originate in the legs and travel up through the right side of the heart and into the lungs.
WordReference Random House Unabridged Dictionary of American English Â© 2016. tread (tred), v., trod, trodâ¢den ortrod, treadâ¢ing, n. v.i. 1  to set down the foot or feet in walking; step; walk.  to step, walk, or trample so as to press, crush, or injure something (usually fol. by on or upon):to tread on a person's foot.
Treads are the workhorses. When treads are installed in a staircase, there is customarily a wedge-shaped mortise or âslotâ cut into the stringers to hold the treads where they belong. The very important, but hidden and often unknown, element of tread installation is a blind or hidden wedge.hen treads are installed in a staircase, there is customarily a wedge-shaped mortise or âslotâ cut into the stringers to hold the treads where they belong. The very important, but hidden and often unknown, element of tread installation is a blind or hidden wedge.