Viewing posts by christian
Nuclear binding energies #2
Posted by: christian on 14 Aug 2016
The semi-empirical mass formula parameters used in the previous post were taken from the text book of J. W. Rohlf (1994) [1]. Another, older set of parameters are presented in the compilation of A. H. Wapstra (1958)[2]. Below we compare each with the experimental data from the OECD-NEA (in the file mass.mas03).
Nuclear binding energies #1
Posted by: christian on 12 Aug 2016
The binding energy of a nucleus is the energy that would be required to split apart each of its constituent protons and neutrons (nucleons). This energy is due to the forces that hold the nucleus together, which may be thought of as a balance between the attractive strong nuclear force and the electromagnetic force (which is repulsive between the positively-charged protons). The binding energy manifests itself in a mass difference between the nucleus and the individual nucleons ($E=mc^2$) and the difference in binding energy between different nuclei is the energy released in the process of nuclear fusion and fission.
Binning a 2D array in NumPy
Posted by: christian on 4 Aug 2016
The standard way to bin a large array to a smaller one by averaging is to reshape it into a higher dimension and then take the means over the appropriate new axes. The following function does this, assuming that each dimension of the new shape is a factor of the corresponding dimension in the old one.
Visualizing the bivariate Gaussian distribution
Posted by: christian in Featured on frontpage on 3 Aug 2016
The multivariate Gaussian distribution of an $n$-dimensional vector $\boldsymbol{x}=(x_1, x_2, \cdots, x_n)$ may be written
Changes in real wages since 2007
Posted by: christian on 1 Aug 2016
The OECD provides a tool for studying the change in average real wages (compared in purchase power parity adjusted US dollars using a 2012 base year). Here is how real wages have changed in 15 countries, visualised on a bar chart visualized with Matplotlib.