Dynamics of colloidal particles with capillary interactions

We investigate the dynamics of colloids at a fluid interface driven by attractive capillary interactions. At submillimeter length scales, the capillary attraction is formally analogous to two-dimensional gravity. In particular it is a non-integrable interaction and it can be actually relevant for collective phenomena in spite of its weakness at the level of the pair potential. We introduce a mean-field model for the dynamical evolution of the particle number density at the interface. For generic values of the physical parameters the homogeneous distribution is found to be unstable against large-scale clustering driven by the capillary attraction. We also show that for the instability to be observable, the appropriate values for the relevant parameters (colloid radius, surface charge, external electric field, etc.) are experimentally well accessible. Our analysis contributes to current studies of the structure and dynamics of systems governed by long-ranged interactions and points towards their experimental realizations via colloidal suspensions.Comment: Matches version accepted for publication. New refs. added, misprints corrected in figs.6,8,9,1

EU Patent System: to be or not to be?

This paper introduce a list of desirable efficiency properties that any a patent system should have in order to enhance innovation, trade competitiveness, employment mobility and economic growth. We briefly overview the literature on patents and discuss the advantages and disadvantages of the present and recent proposals for the future of the European Union Patents System. In particular, we discuss the costinefficiencies observed in the current design of the EU Patent System based in a double structure layer divided in a central European Patent Office (EPO) and several nationalbased patent offices. This paper analyzes the likely backlashes of creating a third layer for a subâ€sample of EU countries. The paper suggests an alternative more efficient Patent System together with some policy implications.Innovation, Patents, Knowledge spillovers, Common European patent, Welfare losses, Patents’ languages, Cultural proximity, Competitive trade

From Growth Spurts to Sustained Growth: The Nature of Growth and Unified Growth Theory

The recent literature on unified growth theory has shed new light on the transition to sustained economic growth. Nevertheless, unified growth theory has not devoted a lot of attention to the nature of economic growth and its impact in the transition from Malthus to Solow. This research presents new evidence on the existence of pre-industrial growth spurts and provides new foundations concerning the nature of economic growth during the Malthus to Solow transition. Following previous research in unified growth theory, sustained economic growth arises due to complementarities between the triple engines of growth of technological development, human capital and the organization of the workplace. In this research, growth spurts are an intrinsic feature of the economy, but throughout history their effect on standards of living is mostly temporary. The rise in living standards only becomes sustained when the complementarity of the triple engines of growth emerges. In Malthusian economies, most technologies were basic and only require straightforward knowledge or human capital, and thus the skill-technology complementarity did not play a role in their development. As a consequence, most technological developments in Malthusian economies generated growth spurts that did not become sustained, although there was a temporary increase in standards of living. However, the increasing complexity of the epistemic knowledge base reported by the historical literature meant that investments in applied technology were progressively more significant, enhancing the role of human capital. After a certain threshold of the knowledge base was surpassed, more and more complex applied technologies were developed, and growth spurts became permanent features of the economy. This research thus captures some of the most important historical features concerning the nature of growth in the transition to sustained economic growth.growth spurts, unified growth theory, sustained economic growth

Theory of capillary-induced interactions beyond the superposition approximation

Within a general theoretical framework we study the effective, deformation-induced interaction between two colloidal particles trapped at a fluid interface in the regime of small deformations. In many studies, this interaction has been computed with the ansatz that the actual interface configuration for the pair is given by the linear superposition of the interface deformations around the single particles. Here we assess the validity of this approach and compute the leading term of the effective interaction for large interparticle separation beyond this so-called superposition approximation. As an application, we consider the experimentally relevant case of interface deformations owing to the electrostatic field emanating from charged colloidal particles. In mechanical isolation, i.e., if the net force acting on the total system consisting of the particles plus the interface vanishes, the superposition approximation is actually invalid. The effective capillary interaction is governed by contributions beyond this approximation and turns out to be attractive. For sufficiently small surface charges on the colloids, such that linearization is strictly valid, and at asymptotically large separations, the effective interaction does not overcome the direct electrostatic repulsion between the colloidal particles.Comment: Minor typos correcte

Renormalized Entanglement Entropy for BPS Black Branes

We compute the renormalized entanglement entropy (REE) for BPS black solutions in ${\cal N}=2$, 4d gauged supergravity. We find that this quantity decreases monotonically with the size of the entangling region until it reaches a critical point, then increases and approaches the entropy density of the brane. This behavior can be understood as a consequence of the REE being driven by two competing factors, namely entanglement and the mixedness of the black brane. In the UV entanglement dominates, whereas in the IR the mixedness takes over.Comment: 6 pages, 4 figures; v2: Typos fixed, citation and clarifying text added, version accepted in Physical Review

Outcome-based theory of work motivation

This paper introduces an outcome-based theory of work motivation. This theory focuses on the individual's expected consequences of his or her action. We identify four different types of expected consequences, or motives. These motives lead to four types of motivation: extrinsic, intrinsic, contributive, and relational. We categorize these outcomes using two criteria: the perceived locus of causality, which defines the origin of the motivation, and the perceived locus of consequence, which defines who receives the consequences of the action. Individuals generally act based on a combination of extrinsic, intrinsic, contributive, and relational motivations, each one having a particular weight. We use the term motivational profile to refer to the particular combination of an individual's motivations in a certain context. Individuals may experience conflict when different alternatives convey different expected consequences (or motives). Resolution of conflicts among motives results in motivational learning. Specifically, the resolution of conflicts among motives of the same type results in calculative learning. On the other hand, the resolution of conflicts among motives of different types results in evaluative learning. Evaluative learning implies a change in the individual's motivational profile.work motivation; locus causality; motivational profile; extrinsic motivation; intrinsic motivation; contributive motivation; relational motivation;

Spin wave vortex from the scattering on Bloch point solitons

The interaction of a spin wave with a stationary Bloch point is studied. The topological non-trivial structure of the Bloch point manifests in the propagation of spin waves endowing them with a gauge potential that resembles the one associated with the interaction of a magnetic monopole and an electron. By pursuing this analogy, we are led to the conclusion that the scattering of spin waves and Bloch points is accompanied by the creation of a magnon vortex. Interference between such a vortex and a plane wave leads to dislocations in the interference pattern that can be measurable by means of magnon holography