No redundancy rCh





Death (no aging)


Damage accumulation (aging)

Figure 5.7. Redundancy creates both damage tolerance and damage accumulation (aging). Systems without redundancy (on the top) fail every time when they are damaged, and therefore damage is not accumulated among survivors (no aging). Redundant systems (on the bottom) can sustain damage because of their redundancy, but this damage tolerance leads to damage accumulation (aging).

dynamics is extensively used in the calculation of the efficacy of sterilization processes in medicine and food preservation (Brock et al., 1994; Davis et al., 1990; Jay, 1996). A similar nonaging pattern of inactivation kinetics is often observed for viruses (Andreadis and Palsson, 1997; Kundi, 1999) and enzymes (Kurganov, 2002; Gouda et al., 2003).

In more complex systems with many vital structures and significant redundancy, every occurrence of damage does not lead to death (unless the environment is particularly hostile) because of their redundancy. Defects accumulate, therefore, giving rise to the phenomenon of aging (mortality increase). Thus, aging is a direct consequence (trade-off) of a system's redundancies, which ensure increased reliability and an increased lifespan of more complex organisms. As defects accumulate, the redundancy in the number of elements finally disappears. As a result of this redundancy exhaustion, the organism degenerates into a system with no redundancy (that is, a system with elements connected in series, in which any new defect leads to death). In such a state, no further accumulation of damage can be achieved, and the mortality rate levels off.

Reliability theory predicts that a system may deteriorate with age even if it is built from nonaging elements with a constant failure rate. The key issue here is the system's redundancy for irreplaceable elements, which is responsible for the aging phenomenon. In other words, each particular step of system destruction/deterioration may seem to be apparently random (no aging, just occasional failure by chance), but if a system failure requires a sequence of several such steps (not just a single step of destruction), then the system as a whole may have an aging behavior.

The positive effect of systems' redundancy is damage tolerance, which decreases the risk of failure (mortality) and increases lifespan. However damage tolerance makes it possible for damage to be tolerated and accumulated over time, thus producing the aging phenomenon.

The next section provides a mathematical illustration for these ideas.

Was this article helpful?

0 0
Staying Young

Staying Young

Discover The Secrets To Staying Young Forever. Discover How To Hinder The Aging Process On Your Body And In Your Life. Do you feel left out when it comes to trying to look young and keeping up with other people your age? Do you feel as though your body has been run down like an old vehicle on its last legs? Those feelings that you have not only affect you physically, but they can also affect you mentally. Thats not good.

Get My Free Ebook

Post a comment