Gompertz law and aging as exclusion effects

2007 ◽  
Vol 8 (5) ◽  
pp. 605-612 ◽  
Author(s):  
Anund Hallén
Keyword(s):  
2007 ◽  
Vol 8 (5) ◽  
pp. 595-603 ◽  
Author(s):  
Anund Hallén
Keyword(s):  

2009 ◽  
Vol 11 (1) ◽  
Author(s):  
Anund Hallén
Keyword(s):  

2008 ◽  
Vol 10 (4) ◽  
pp. 517-522 ◽  
Author(s):  
Anund Hallén
Keyword(s):  

2014 ◽  
Vol 20 (2) ◽  
pp. 66-73 ◽  
Author(s):  
Leonid A. Gavrilov ◽  
Natalia S. Gavrilova ◽  
Charles Austin Stone ◽  
Anne Zissu

2000 ◽  
Vol 2000 (2) ◽  
pp. 168-179 ◽  
Author(s):  
W. J. Willemse ◽  
H. Koppelaar

2006 ◽  
Vol 14 (02) ◽  
pp. 303-314 ◽  
Author(s):  
YUJUAN ZHANG ◽  
ZHILONG XIU ◽  
LANSUN CHEN

In this paper we investigate the optimal harvesting problems of a single species with Gompertz law of growth. Based on continuous harvesting models, we propose impulsive harvesting models with constant harvest or proportional harvest. By using the discrete dynamical systems determined by the stroboscopic map, we discuss existence, stability and global attractivity of positive periodic solutions, and obtain the maximum sustainable yield and the corresponding optimal population level. At last, we compare the maximum sustainable yield of impulsive harvest with that of continuous harvest, and point out that proportional harvest is superior to constant harvest.


2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S966-S967
Author(s):  
Natalia S Gavrilova ◽  
Leonid Gavrilov

Abstract In order to develop genuine anti-aging interventions it is important to find the best estimate of the aging rate in humans, which is often measured as a slope parameter of the Gompertz law. The compensation effect of mortality (CEM), refers to mortality convergence, when higher values for the slope parameter are compensated by lower values of the intercept parameter (initial mortality) in different populations of a given species. The age of this convergence point is called the "species-specific life span". Due to CEM, factors associated with life span extension are usually accompanied by paradoxical increase in actuarial aging rate. We evaluated the stability of CEM by analyzing the United Nations abridged life tables for 241 countries and regions and estimating parameters of the Gompertz-Makeham model using method of non-linear regression in the age interval 30-80 years. We found that the species-specific lifespan is equal to 94.5 ± 0.5 years, which is the same as reported in the past for years before the 1960s: 95 ± 3 years (Gavrilov, Gavrilova, 1991). Thus, the convergence point of CEM is stable despite significant mortality decline over past 50 years and is not affected by factors decreasing mortality at younger ages. Populations deviating from CEM with apparently slow aging (with both slow actuarial aging rate and low intercept parameter) have been identified. The existence of CEM in mice (ITP data) allowed us to find interventions that are able to both extend lifespan and slow the actuarial aging rate giving promise for radical life extension.


2019 ◽  
Vol 12 (02) ◽  
pp. 1950018
Author(s):  
P. D. N. Srinivasu ◽  
Simon D. Zawka

This work presents an optimal harvesting problem associated with a single-species population governed by Gompertz law in a seasonally fluctuating environment. The influence of environmental fluctuation is accommodated by choosing the coefficients in the differential equation to be periodic functions with the same period and restriction on the harvesting effort is accommodated by considering binding constraints on the control variable. Hence, a linear optimal control problem has been considered where the state dynamics is governed by Gompertz equation and the control variable is subject to the binding constraints. With the help of maximum principle and the concept of blocked intervals, an optimal periodic solution has been obtained which is followed by the construction of optimal solution using the theory of most rapid approach. Important results of the study are demonstrated through numerical simulations.


2020 ◽  
Vol 21 (8) ◽  
pp. 2905
Author(s):  
Maher A. Dayeh ◽  
George Livadiotis ◽  
Farzan Aminian ◽  
Kwan H. Cheng ◽  
James L. Roberts ◽  
...  

The association between plasma cholesterol levels and the development of dementia continues to be an important topic of discussion in the scientific community, while the results in the literature vary significantly. We study the effect of reducing oxidized neuronal cholesterol on the lipid raft structure of plasma membrane. The levels of plasma membrane cholesterol were reduced by treating the intact cells with methyl-ß-cyclodextrin (MßCD). The relationship between the cell viability with varying levels of MßCD was then examined. The viability curves are well described by a modified form of the empirical Gompertz law of mortality. A detailed statistical analysis is performed on the fitting results, showing that increasing MßCD concentration has a minor, rather than significant, effect on the cellular viability. In particular, the dependence of viability on MßCD concentration was found to be characterized by a ~25% increase per 1 μM of MßCD concentration.


Sign in / Sign up

Export Citation Format

Share Document