Systems and methods are disclosed for visually indicating an occurrence of an event. Through applying operating voltage on the thermal sensitive element within the electric control valve and then swiftly transmitting heat to the memory alloy spring, when the temperature of the memory alloy spring reaches to a deforming temperature, the memory alloy spring deforms and expands and thus pushes the pushing rod to move. The radio signal receiving system operates without any conventional self-contained antenna and includes a radio signal receiving carrier which is either made from a conventional conducting wire or made of a metal to thereby enhance the efficiency of signal reception. The guides are resiliently deformable to allow concurrent engagement of each roller element with both the inner and outer races. The invention also concerns the use of VCAM-1 ligands for making a medicine for treating a cardiovascular disease.