Last time we have written on the power spectral density and we have "analyzed" deterministic periodic time series. This time we will consider spectral densities of some stochastic processes.

Here, on the Physics of Risk, we frequently talk about two essential statistical features of the time series - probability and spectral densities. The probability density function should well known to our readers - it is related to the distribution of time series values. So let us now discuss the power spectral density.

In classical physics differential equations is the main tool to mathematically describe dynamical systems. Having obtained the mathematical descriptions of the system we should be able to predict the evolution of the system. It is noted that the evolution of the classical systems is pretty trivial - no matter what the initial condition is the system will "find" the stable state. Usually dissipative forces (such as frictions) are to be blamed for this. Though not all systems are so simple...

The most active and well known scientists contributing towards FuturICT project have organized their ideas into few articles, which discuss the current situation in contemporary complex social system modeling. These articles we published in a special issue of "The European Physical Journal Special Topics". Most of the articles are available for free, thus we invite you to familiarize yourselves with them.

Read the special issue of EPJ »

Recently on my Facebook news feed I found one article, which was rather interesting. "Teaching mathematics differently?" - ironical thought crossed my mind, while at the same time recalling some stand up comedians telling "wild" stories about the problem-based learning. It is truly funny to hear that children nowadays are forced to help the squirrel to count the nuts! Or to solve another default setup: "10 apples + 4 pears = 48 Litas, while 5 apples + 6 pears = 32 Litas, if so then how many Litas does a single apple or pear cost?" Why should anyone solve this problem in this way? Can't the client just look up the price tags? Or check his receipt?