The Stabilizing Role of Global Alliances in the Dynamics of Coalition Forming

Coalition forming is investigated among countries, which are coupled with short range interactions, under the influence of external fields produced by the existence of global alliances. The model rests on the natural model of coalition forming inspired from Statistical Physics, where instabilities are a consequence of decentralized maximization of the individual benefits of actors within their long horizon of rationality as the ability to envision a way through intermediate loosing states, to a better configuration. The effects of those external incentives on the interactions between countries and the eventual stabilization of coalitions are studied. The results shed a new light on the understanding of the complex phenomena of stabilization and fragmentation in the coalition dynamics and on the possibility to design stable coalitions. In addition to the formal implementation of the model, the phenomena is illustrated through some historical cases of conflicts in Western Europe.Comment: 19 pages, 12 figure

The Birth of the Idea of Perfectibility: From the Enlightenment to Transhumanism

Starting from the Age of Enlightenment, a person’s ability of self-improvement, or perfectibility, is usually seen as a fundamental human feature. However, this term, introduced into the philosophical vocabulary by J.-J. Rousseau, gradually acquired additional meaning – largely due to the works of N. de Condorcet, T. Malthus and C. Darwin. Owing to perfectibility, human beings are not only able to work on themselves: by improving their abilities, they are also able to change their environment (both social and natural) and create favorable conditions for their existence. It is no coincidence that perfectibility became the key concept of the idea of social progress proposed by French thinkers in the Age of Enlightenment, despite the fact that later it was criticized, above all, by English authors, who justified its organic and biological nature and gave a different evolutionary interpretation to this concept, without excluding perfectibility from the philosophical vocabulary. In this article, we address the opposition and mutual counterarguments of these two positions. Beyond that, we draw a parallel with some of the ideas of S. Kapitsa, who proved to be not only a critic of Malthusianism but also a direct disciple of Condorcet. In the modern age, the ideas of human self-improvement caused the development of transhumanist movement. Condorcet is more relevant than ever, and today his theory of the progress of the human mind, which influenced the genesis of modern historical science, needs a re-thinking in the newest perspective of improving the mental and physical human nature with the help of modern technologies

Wetting, roughness and hydrodynamic slip

The hydrodynamic slippage at a solid-liquid interface is currently at the center of our understanding of fluid mechanics. For hundreds of years this science has relied upon no-slip boundary conditions at the solid-liquid interface that has been applied successfully to model many macroscopic experiments, and the state of this interface has played a minor role in determining the flow. However, the problem is not that simple and has been revisited recently. Due to the change in the properties of the interface, such as wettability and roughness, this classical boundary condition could be violated, leading to a hydrodynamic slip. In this chapter, we review recent advances in the understanding and expectations for the hydrodynamic boundary conditions in different situations, by focussing mostly on key papers from past decade. We highlight mostly the impact of hydrophobicity, roughness, and especially their combination on the flow properties. In particular, we show that hydrophobic slippage can be dramatically affected by the presence of roughness, by inducing novel hydrodynamic phenomena, such as giant interfacial slip, superfluidity, mixing, and low hydrodynamic drag. Promising directions for further research are also discussed.Comment: 36 pages, 19 figures. This chapter would be a part of "Nanoscale liquid interfaces" boo

Wetting, roughness and flow boundary conditions

We discuss how the wettability and roughness of a solid impacts its hydrodynamic properties. We see in particular that hydrophobic slippage can be dramatically affected by the presence of roughness. Owing to the development of refined methods for setting very well-controlled micro- or nanotextures on a solid, these effects are being exploited to induce novel hydrodynamic properties, such as giant interfacial slip, superfluidity, mixing, and low hydrodynamic drag, that could not be achieved without roughness.Comment: 28 pages, 14 figures, 4 tables; accepted for publication in Journal of Physics: Condensed Matte

Hydrodynamic interaction with super-hydrophobic surfaces

Patterned surfaces with large effective slip lengths, such as super-hydrophobic surfaces containing trapped gas bubbles, have the potential to reduce hydrodynamic drag. Based on lubrication theory, we analyze an approach of a hydrophilic disk to such a surface. The drag force is predicted analytically and formulated in terms of a correction function to the Reynolds equation, which is shown to be the harmonic mean of corrections expressed through effective slip lengths in the two principal (fastest and slowest) orthogonal directions. The reduction of drag is especially pronounced for a thin (compared to texture period) gap. It is not really sensitive to the pattern geometry, but depends strongly on the fraction of the gas phase and local slip length at the gas area.Comment: 20 pages, 7 figure

Effective slip in pressure-driven flow past super-hydrophobic stripes

Super-hydrophobic array of grooves containing trapped gas (stripes), have the potential to greatly reduce drag and enhance mixing phenomena in microfluidic devices. Recent work has focused on idealized cases of stick-perfect slip stripes, with limited guidance. Here, we analyze the experimentally relevant situation of a pressure-driven flow past striped slip-stick surfaces with arbitrary local slip at the gas sectors. We derive analytical formulas for maximal (longitudinal) and minimal (transverse) directional effective slip lengths that can be used for any surface slip fraction (validated by numerical calculations). By representing eigenvalues of the slip length-tensor, they allow us to obtain the effective slip for any orientation of stripes with respect to the mean flow. Our results imply that flow past stripes is controlled by the ratio of the local slip length to texture size. In case of a large (compared to the texture period) slip at the gas areas, surface anisotropy leads to a tensorial effective slip, by attaining the values predicted earlier for a perfect local slip. Both effective slip lengths and anisotropy of the flow decrease when local slip becomes of the order of texture period. In the case of small slip, we predict simple surface-averaged, isotropic flows (independent of orientation). These results provide a framework for the rational design of super-hydrophobic surfaces and devices.Comment: 10 pages, 4 figures, revised versio

Statistical Inference in Large Antenna Arrays under Unknown Noise Pattern

In this article, a general information-plus-noise transmission model is assumed, the receiver end of which is composed of a large number of sensors and is unaware of the noise pattern. For this model, and under reasonable assumptions, a set of results is provided for the receiver to perform statistical eigen-inference on the information part. In particular, we introduce new methods for the detection, counting, and the power and subspace estimation of multiple sources composing the information part of the transmission. The theoretical performance of some of these techniques is also discussed. An exemplary application of these methods to array processing is then studied in greater detail, leading in particular to a novel MUSIC-like algorithm assuming unknown noise covariance.Comment: 25 pages, 5 figure