Efficient simulation of stochastic chemical kinetics with the Stochastic Bulirsch-Stoer extrapolation method

BackgroundBiochemical systems with relatively low numbers of components must be simulated stochastically in order to capture their inherent noise. Although there has recently been considerable work on discrete stochastic solvers, there is still a need for numerical methods that are both fast and accurate. The Bulirsch-Stoer method is an established method for solving ordinary differential equations that possesses both of these qualities.ResultsIn this paper, we present the Stochastic Bulirsch-Stoer method, a new numerical method for simulating discrete chemical reaction systems, inspired by its deterministic counterpart. It is able to achieve an excellent efficiency due to the fact that it is based on an approach with high deterministic order, allowing for larger stepsizes and leading to fast simulations. We compare it to the Euler ?-leap, as well as two more recent ?-leap methods, on a number of example problems, and find that as well as being very accurate, our method is the most robust, in terms of efficiency, of all the methods considered in this paper. The problems it is most suited for are those with increased populations that would be too slow to simulate using Gillespie’s stochastic simulation algorithm. For such problems, it is likely to achieve higher weak order in the moments.ConclusionsThe Stochastic Bulirsch-Stoer method is a novel stochastic solver that can be used for fast and accurate simulations. Crucially, compared to other similar methods, it better retains its high accuracy when the timesteps are increased. Thus the Stochastic Bulirsch-Stoer method is both computationally efficient and robust. These are key properties for any stochastic numerical method, as they must typically run many thousands of simulations

ON THE SIMULATION OF IC CHIP TEMPERATURE DISTRIBUTION

A new algorithm is found and a computer program developed for the more exact calculation of lC chip surface temperature distribution. The algorithm takes into account the effect of non-ideal (non-isotherm) heat-sink and the heat conductivity of bonding wires as well. The simulation is based on the fast Fourier-cosinus calculation method. The heat conducting effect of lC's environment is considered by linear calculation methods. The computer simulation is supported by measurements taken by liquid crystal

Human behaviour: Sex ratio and the city

SummaryThe ratio of males to females in a population is known to influence the behaviour, life histories and demography of animals. A recent experimental study finds that sex ratio also affects human economic behaviour, and in a manner consistent with evolutionary theory

Az utódgondozási rendszer szerepe a függőcinege ivari allokációjában = The role of parental care in sex allocation of Penduline Tits

A kutatasunk fo celja a fuggocinegek ivari konfliktusanak vizsgalata volt, specifikusan annak felmerese, hogy az ivari konfliktus hogyan befolyasolja a szex allokaciot. Tobb lenyeges lepest tettunk a celok elerese fele. Egyreszt, egy terepi vizsgalatsorozatban kumutattuk, hogy a himek szemcsikjanak merete es kondiciioja befolyasolja a szulok utodgondozo viselkedeset. Masreszt, egy aviariumi kiserletben tesztetunk 2 jelleget amik varhatoan szerepet jatszanak a tojok parvalasztasaban. Harmadreszt, becsultuk a himekl es nostenyek szaporodasi sikeret, es kimutattuk, hogy a neme erdeke ellentetes. | The objectiove of the project was to investigate sexual conflict in penduline tits, specifically, to assess the implication of this conflict for sex allocation. We made important advances to achieve this objective. First, carried out a series of field investigations that identified the eye-stripe size of males and their body condition as traits involved in parental decision. Second, in an aviary we tested 2 putative traits involved in female choice. Finally, we quantified the reproductive success of male and female penduline tits, and showed their antagonistic interest