Bonabeau hierarchy models revisited

What basic processes generate hierarchy in a collective? The Bonabeau model provides us a simple mechanism based on randomness which develops self-organization through both winner/looser effects and relaxation process. A phase transition between egalitarian and hierarchic states has been found both analytically and numerically in previous works. In this paper we present a different approach: by means of a discrete scheme we develop a mean field approximation that not only reproduces the phase transition but also allows us to characterize the complexity of hierarchic phase. In the same philosophy, we study a new version of the Bonabeau model, developed by Stauffer et al. Several previous works described numerically the presence of a similar phase transition in this later version. We find surprising results in this model that can be interpreted properly as the non-existence of phase transition in this version of Bonabeau model, but a changing in fixed point structure

Income Inequality in the 21st Century -- A biased summary of Piketty's Capital in the Twenty-First Century

Capital usually leads to income, and income is more accurately and easily measured. Thus we summarize income distributions in USA, Germany, etc.Comment: Two pages plus many figures. Revision corrects typos and enlarges captions 1 and

Threshold value of three dimensional bootstrap percolation

The following article deals with the critical value p_c of the three-dimensional bootstrap percolation. We will check the behavior of p_c for different lengths of the lattice and additionally we will scale p_c in the limit of an infinite lattice.Comment: 8 pages including 9 figures for Int.J.Mod.Phys.

The Complexity of Biological Ageing

The present review deals with the computer simulation of biological ageing as well as its demographic consequences for industrialized societies.Comment: For Fractal 2004 proceedings, Vancouver; 12 pages of review including 6 fig

“The Fall of a Sparrow”: The (Un)timely Death of Elmer Ellsworth and the Coming of the Civil War

On the morning of May 24, 1861, a group of Union cadets marched into the city of Alexandria, Virginia. The cohort looked peculiar in their flamboyant Zouave uniforms with bright blue shirts and flashy red sashes. They were led by a dashing young colonel named Elmer Ephraim Ellsworth and charged with occupying the city. Noticing a Confederate flag flying high on the roof of a hotel called the Marshall House, Ellsworth and a few of his men entered the building, determined to bring it down. The trip up the stairs was easygoing and the flag was quickly retrieved without incident. But on the way down everything went wrong. The innkeeper, a Confederate sympathizer named James W. Jackson, appeared with a shotgun and fired, piercing Ellsworth’s heart. As he stumbled backward he uttered his final words: “My God!” Almost immediately, Corporal Francis Brownell aimed his rifle directly at Jackson’s forehead and shot his colonel’s murderer. In the coming conflict scores of men and boys would be slaughtered in similar fashion causing Americans to rethink the grim and brutal realities of modern war. The deaths of Ellsworth and Jackson constituted the first official battle fatalities of the Civil War, but many more followed. [excerpt