Actually the principal ageing classes considered in the literature can be defined in terms of log-concavity or log-convexity (see, for instance, [[9], Ch. 2]).
The assessment reveals that hormetic dose response relationships occur in males and females of numerous animal models in all principal age groups as well as across species displaying a broad range of differential susceptibilities to toxic agents.
In reliability theory, the principal ageing properties considered for a random variable involve the study of the log-concavity (positive ageing) or log-convexity (negative ageing) of a certain function (which usually is the distribution function, survival function or density function).
The food consumption data were subdivided by principal age bands employed in the EFSA Comprehensive Food Consumption Database: 1 2, 3 9, 10 17 and 18+ years (there were no data on children less than 1 year; and the elderly were grouped with adults).
An increasing average age for farmers and ranchers has been reported by the USDA National Agricultural Statistics Service showing that the mean age of principal farm operators has increased from 50 years in 1978 to 54 years in 1997, 57 years in 2007, and 58 years in 2012 with 33%% of the nation's principal operators aged 65 years or older (USDA Census of agriculture 2012).
Writing in The New York Times Book Review, William Laurence, a former Times science editor, praised Mr. Lamont for preserving the recollections of the aging "principal protagonists" of the Manhattan Project.
By 1997 Dr. Guarente's group had established a principal mechanism of aging in yeast: the nucleolus sooner or later gets clogged up with waste circles of ribosomal material until it can no longer produce ribosomes and the yeast cell dies.
Accumulation of DNA damage leading to adult stem cell exhaustion has been proposed to be a principal mechanism of aging.
The principal effects of aging are the exponential rise in the incidence and mortality rates of cancer and non-cancer diseases and the progressive increase in tissue degeneration and atrophy.
Dallas Anderson, an expert on the epidemiology of dementia at the National Institute on Aging, the principal financer of dementia research in the United States, said the new studies were "rigorous and are strong evidence".
