Cumulative Causation and Evolutionary Micro-Founded Technical Change: A Growth Model with Integrated Economies

We propose to develop in this paper an alternative approach to the New Growth Theory to analyse growth rate divergence among integrated economies. The model presented here considers economic growth as a disequilibrium process. It introduces in a cumulative causation framework, micro-founded process of technical change taking into account elements rooted in evolutionary and Neo-Austrian literature. We then attempt to open the "Kaldor-Verdoorn law black-box" using a micro-level modelling of industrial dynamics. We use this framework to study the nature and sources of growth rate divergence, focusing on the eect of some macro-economic parameters (income elasticities) and of some technological parameters (technological opportunities and absorptive capacities). If the results remain broadly in Kaldorian lines, this framework allows for more subtle considerations of growth rate divergence.Cumulative Growth, Technical Change, International Trade

Massive star models with magnetic braking

Magnetic fields at the surface of a few early-type stars have been directly detected. These fields have magnitudes between a few hundred G up to a few kG. In one case, evidence of magnetic braking has been found. We investigate the effects of magnetic braking on the evolution of rotating ($\upsilon_{\rm ini}$=200 km s$^{-1}$) 10 M$_\odot$ stellar models at solar metallicity during the main-sequence (MS) phase. The magnetic braking process is included in our stellar models according to the formalism deduced from 2D MHD simulations of magnetic wind confinement by ud-Doula and co-workers. Various assumptions are made regarding both the magnitude of the magnetic field and of the efficiency of the angular momentum transport mechanisms in the stellar interior. When magnetic braking occurs in models with differential rotation, a strong and rapid mixing is obtained at the surface accompanied by a rapid decrease in the surface velocity. Such a process might account for some MS stars showing strong mixing and low surface velocities. When solid-body rotation is imposed in the interior, the star is slowed down so rapidly that surface enrichments are smaller than in similar models with no magnetic braking. In both kinds of models (differentially or uniformly rotating), magnetic braking due to a field of a few 100 G significantly reduces the angular momentum of the core during the MS phase. This reduction is much greater in solid-body rotating models.Comment: 4 pages, 4 figures, accepted for publication as a Letter in Astronomy and Astrophysic

Universal bounds on current fluctuations

For current fluctuations in non-equilibrium steady states of Markovian processes, we derive four different universal bounds valid beyond the Gaussian regime. Different variants of these bounds apply to either the entropy change or any individual current, e.g., the rate of substrate consumption in a chemical reaction or the electron current in an electronic device. The bounds vary with respect to their degree of universality and tightness. A universal parabolic bound on the generating function of an arbitrary current depends solely on the average entropy production. A second, stronger bound requires knowledge both of the thermodynamic forces that drive the system and of the topology of the network of states. These two bounds are conjectures based on extensive numerics. An exponential bound that depends only on the average entropy production and the average number of transitions per time is rigorously proved. This bound has no obvious relation to the parabolic bound but it is typically tighter further away from equilibrium. An asymptotic bound that depends on the specific transition rates and becomes tight for large fluctuations is also derived. This bound allows for the prediction of the asymptotic growth of the generating function. Even though our results are restricted to networks with a finite number of states, we show that the parabolic bound is also valid for three paradigmatic examples of driven diffusive systems for which the generating function can be calculated using the additivity principle. Our bounds provide a new general class of constraints for nonequilibrium systems.Comment: 19 pages, 13 figure

Universal bound on the efficiency of molecular motors

The thermodynamic uncertainty relation provides an inequality relating any mean current, the associated dispersion and the entropy production rate for arbitrary non-equilibrium steady states. Applying it here to a general model of a molecular motor running against an external force or torque, we show that the thermodynamic efficiency of such motors is universally bounded by an expression involving only experimentally accessible quantities. For motors pulling cargo through a viscous fluid, a universal bound for the corresponding Stokes efficiency follows as a variant. A similar result holds if mechanical force is used to synthesize molecules of high chemical potential. Crucially, no knowledge of the detailed underlying mechano-chemical mechanism is required for applying these bounds.Comment: Invited contribution to proceedings of STATPHYS26, Lyo

The inter-generational persistence of child labor

The authors use the"Pesquisa Nacional por Amostragem a Domicilio"(PNAD) data for Brazil. Their paper asks two related questions. First, does the child labor status of parents impact the child labor incidence of their children? The authors find strong evidence that it does. Second, is this link only a function of permanent family income or is there a direct link between the child labor status of the parents, and their children? They find evidence that such a direct link exists. This complements their previous research (Emerson and Souza 2002) in which they went on to ask if a person works as a child, would this increase the probability of his, or her child working by more than what can be explained, by the fact that the person will be poor as an adult (by virtue of having been a child worker), and therefore compelled to send the child to work? The answer to this is also yes. Hence, the presence of social factors can cause the perpetuation of child labor through non-income channels. It is, for instance, possible that having been a child laborer oneself, affects one's social norms, and attitude to child labor (Basu 1999, Lopez-Calva 2002), such that one is more prone to send ones'own child to work.

Multi-Boson Interactions at the LHC

This review covers results on the production of all possible electroweak boson pairs and 2-to-1 vector boson fusion at the CERN Large Hadron Collider (LHC) in proton-proton collisions at a center of mass energy of 7 and 8 TeV. The data were taken between 2010 and 2012. Limits on anomalous triple gauge couplings (aTGCs) then follow. In addition, data on electroweak triple gauge boson production and 2-to-2 vector boson scattering yield limits on anomalous quartic gauge boson couplings (aQGCs). The LHC hosts two general purpose experiments, ATLAS and CMS, which have both reported limits on aTGCs and aQGCs which are herein summarized. The interpretation of these limits in terms of an effective field theory is reviewed, and recommendations are made for testing other types of new physics using multi-gauge boson production.Comment: 53 pages, 48 figures, 4 table

Nonlinear disturbance evolution in a two-dimensional boundary layer along an elastic plate and induced radiated sound

The interaction between a boundary-layer flow and an elastic plate is addressed by direct numerical simulation, taking into account the full coupling between the fluid flow and the flexible wall. The convectively unstable flow state is harmonically forced and two-dimensional nonlinearly saturated wavelike disturbances are computed along archetype-plates with respect to stiffness and natural frequencies. In the aim of determining the low-Mach-number radiated sound for the system, the simulation data are used to solve the Lighthill’s equation in terms of a Green’s function in the wavenumber-frequency space. Different degrees of fluid-structure coupling are implemented in the radiated sound model and the resulting acoustic pressure levels are compared. The sound radiation levels are shown to be increased in the presence of flexible walls with however significant differences in the radiated pressure levels for different coupling assumptionsThe authors gratefully acknowledge Thales Underwater Systems and DCNS for their financial support to this work

Choix d'un modèle de pyrolyse ménagée du bois à l'échelle de la microparticule en vue de la modélisation macroscopique

Par définition la pyrolyse ménagée du bois est la décomposition physique et chimique de matières organiques sous l'action de la chaleur et en absence d'oxygène. Comprendre ce phénomène passe d'abord par l'identification des mécanismes réactionnels et la détermination des paramètres cinétiques mis en jeu lors de la dégradation thermique du bois et de ses constituants majeurs, c'est-à-dire cellulose, hémicelluloses et lignines. La richesse et la diversité des résultats issus de la littérature spécialisée rendent compte de la difficulté à expliquer ces cinétiques complexes. Cette étude se propose de contribuer de façon innovante au bois traité à haute température en proposant une approche théorique à l'échelle de la microparticule en vue d'une modélisation macroscopique des phénomènes couplés « thermiques, chimiques et physiques ». En restituant les résultats d'une étude bibliographique poussée, nous avons fait le choix de retenir une approche analytique cherchant à séparer les trois composés principaux du bois et à caractériser chacun d'entre eux séparément