Natural selection, which includes sexual selection, is the fact that some traits make it more likely for an organism to survive and reproduce. Population genetics describes natural selection by defining fitness as a propensity or probability of survival and reproduction in a particular environment. The fitness is normally given by the symbol w=1-s where s is the selection coefficient.
Atrial fibrillation with RVR (Rapid Ventricular Response) is a heart condition caused by irregular electrical activity that results in irregular contractions of the heart walls and its chambers. The heart (atrium), shakes with a rapid tremulous movement or makes fine irregular twitching movements, generally referred to as fibrillating.
SCR means Silicon Controlled Rectifier. This device belongs to the family THYRISTORS. Thyristors denotes a family of semiconductor devices used for power control in DC and AC system. At present , the use of SCR is well spread and so vast that the word thyristor becomes synonymous with SCR. In construction, it is a pnpn device .