@article {Pi{\~n}ol2011101, title = {Catastrophic senescence and semelparity in the Penna aging model}, journal = { Theory Biosci.}, volume = {130}, number = {2}, year = {2011}, note = {cited By 2}, pages = {101-106}, abstract = {
The catastrophic senescence of the Pacific salmon is among the initial tests used to validate the Penna aging model. Based on the mutation accumulation theory, the sudden decrease in fitness following reproduction may be solely attributed to the semelparity of the species. In this work, we report other consequences of mutation accumulation. Contrary to earlier findings, such dramatic manifestation of aging depends not only on the choice of breeding strategy but also on the value of the reproduction age, R, and the mutation threshold, T. Senescence is catastrophic when T <= R. As the organism{\textquoteright}s tolerance for harmful genetic mutations increases, the aging process becomes more gradual. We observe senescence that is threshold dependent whenever T \> R. That is, the sudden drop in survival rate occurs at age equal to the mutation threshold value.
}, doi = {10.1007/s12064-010-0115-7}, author = {Chrysline Margus N Pi{\~n}ol and Ronald Banzon} } @article {Pi{\~n}ol20111295, title = {Stability in a population model without random deaths by the Verhulst factor}, journal = {Physica A}, volume = {390}, number = {7}, year = {2011}, note = {cited By 1}, pages = {1295-1299}, abstract = {
A large amount of population models use the concept of a carrying capacity. Simulated populations are bounded by invoking finite resources through a survival probability, commonly referred to as the Verhulst factor. The fact, however, that resources are not easily accounted for in actual biological systems makes the carrying capacity parameter ill-defined. Henceforth, we deem it essential to consider cases for which the parameter is unnecessary. This work demonstrates the possibility of Verhulst-free steady states using the Penna aging model, with one semelparous birth per adult. Stable populations are obtained by setting a mutation threshold that is higher than the reproduction age.
}, doi = {10.1016/j.physa.2010.11.046}, author = {Chrysline Margus N Pi{\~n}ol and Ronald S. Banzon} } @conference {357, title = {Penna model estimate of improved medical care in the Philippines}, year = {2010}, month = {14{\textendash}16 Jun 2010}, pages = {59}, publisher = {10th Science Council of Asia Conference}, address = {Pasay City}, abstract = {The average life expectancy at birth is one indicator of the overall health of a country. In a Penna model that accounts for enhancements in medical services and welfare, the effect of heritable diseases is diminished. Individuals may live longer with probability equal to the relative increase in health care. Choosing the 1950 data for the Philippine population as baseline, the 44\% rise in average life span of Filipinos from then to 1995 may be attributed to a 20\% improvement in medical care. The 2010 life expectancy estimate follows from a 6\% increase in the quality of medical assistance during the last 15 years.}, url = {http://www.scj.go.jp/en/sca/activities/conferences/conf_10.html}, author = {Chrysline Margus N Pi{\~n}ol and Ronald S. Banzon} } @inproceedings {258, title = {Penna model estimate of medical care improvement}, booktitle = {Proceedings of the 28th Samahang Pisika ng Pilipinas Physics Congress}, year = {2010}, month = {25{\textendash}27 Oct 2010}, pages = {SPP-2010-001}, address = {Meralco Management and Leadership Development Center, Antipolo City}, abstract = {
Quantitative estimates for the quality of care are obtained from a Penna model that incorporates medical care. Enhancements in health services and welfare increase the average lifespan by decreasing the effect of heritable diseases. Feasibility of the approach was demonstrated by fitting simulation results with the Philippine life expectancy data. We find that the relative increase in lifespan is proportional to the improvement in care. The Penna model estimates of life expectancy compare well with the UN projections for the Philippine population.
}, author = {Chrysline Margus Pi{\~n}ol and Ronald S. Banzon} } @inproceedings {pinol-spp-2009, title = {Obtaining finite populations in a Verhulst-free 8-bit Penna model with periodic change in reproduction}, booktitle = {Proceedings of the 27th Samahang Pisika ng Pilipinas Physics Congress}, year = {2009}, month = {28{\textendash}30 Oct 2009}, pages = {SPP-2009-033}, address = {Development Academy of the Philippines Convention Center, Tagaytay City}, abstract = {
Periodic changes in reproduction age slow down population growth or decay. The minimum reproductive age in an 8-bit, Verhulst-free Penna model varied repeatedly between two values. It is an invariable characteristic of an individual which is set at birth. A steady state is found when the period for the smaller reproductive age is slightly longer.
}, author = {Chrysline Margus Pi{\~n}ol and Ronald S. Banzon} } @inproceedings {pi{\~n}ol-spp-2008, title = {Reproduction age and survival of a Verhulst-free 8-bit Penna population}, booktitle = {Proceedings of the 26th Samahang Pisika ng Pilipinas Physics Congress}, year = {2008}, month = {22{\textendash}24 Oct 2008}, pages = {SPP-2008-071}, address = {University of the Phlippines Baguio, Baguio City}, abstract = {
A Verhulst-free Penna model is shown to be equivalent to a Malthusian model. The population is driven to exponentially increase or decrease with time depending on the value of its minimum reproductive age. This demonstration justifies its identification as a critical parameter. Unlike the Malthusian model however, we are able to obtain a relatively persistent population by imposing a distribution for the critical minimum reproductive age values.
}, author = {Chrysline Margus Pi{\~n}ol and Ronald S. Banzon} } @inproceedings {pi{\~n}ol-spp-2007, title = {A finite population without imposing the Verhulst factor}, booktitle = {Proceedings of the 25th Samahang Pisika ng Pilipinas Physics Congress}, year = {2007}, month = {24{\textendash}26 Oct 2007}, pages = {SPP-2007-100}, address = {University of the Phlippines Los Ba{\~n}os, Laguna}, abstract = {
The necessity of imposing the concept of a carrying capacity was investigated within the framework of the Penna Model. We find that the number of deaths in a population approaches a saturation point. The carrying capacity {\textendash} Verhulst factor, is the main contributing factor for deaths, over 70\%, in an 8-bit Penna model. Only 3\% and 20\% of the deaths are caused by old age and mutation accumulation, respectively. However, the effect of the common method of accounting for a carrying capacity is diminished as the bit-string length of the Penna Model is decreased. Furthermore, at bit-string length of 2, the Verhulst factor may be removed while still maintaining a finite population.
}, author = {Chrysline Margus Pi{\~n}ol and Ronald S. Banzon} }