The Ising spin model in multiple helices with hierarchically organized interactions is investigated using Monte Carlo simulations. The numerical result of specific heat shows that the Curie temperature of the ferromagnetic transition is strongly dependent on to what extent the basal helix is...

We investigate the dynamics of a population in periodically changing external conditions and we determine the survival chance as a function of the selection pressure and changeability. We compare two extended models. In one, an individual is characterized by its genetic structure from which a...

We study the effect of mutations in a simple model of colonization, based on Monte Carlo simulations. When the population colonizes the whole available habitat, a maximum population density is reached, which depends on the mutation rate. Depending on the values of other parameters, such as...

Very recently we developed a dynamic network model for eco-systems that achieved “unification” of “micro” and “macro”-evolution. We now propose an extension of our model so as to stabilize the eco-system and describe speciation in a more realistic manner.

We modify twice the Penna model for biological ageing. First, we introduce back (good) mutations and a memory for them into the model. It allows us to observe an improvement of the species fitness over long-time scales as well as punctuated equilibrium. Second, we adopt a food/space competition...

We propose a generic model of eco-systems, with a hierarchical food web structure. In our computer simulations, we let the eco-system evolve continuously for so long that we can monitor extinctions as well as speciations over geological time scales. Speciation leads not only to horizontal...

Galam's model of people voting always against the majority is shown to give for the quenched case different results than the original annealed model. For people diffusing on a lattice, Galam's phase transitions happen only at higher concentrations of people.

Based on a new Geographic Information Systems (GIS) grid-basedthree-dimensional (3-D) deterministic model and taking the slopeunit as the mapping unit, this study maps landslide hazard usingthe 3-D safety factor index and failure probability. Assuming theinitial slip to be the lower part of an...

In this paper, two tests for structural hypotheses on cointegration vectors are evaluated in a Monte Carlo study. The tests are the likelihood ratio test proposed by Johansen (1991) and the test for stationarity proposed by Kwiatkowski et al (1992). The analysis of the likelihood ratio test is...