Griffiths phases in the contact process on complex networks

Dynamical processes occurring on top of complex networks have become an exciting area of research. Quenched disorder plays a relevant role in general dynamical processes and phase transitions, but the effect of topological quenched disorder on the dynamics of complex networks has not been systematically studied so far. Here, we provide heuristic and numerical analyses of the contact process defined on some complex networks with topological disorder. We report on Griffiths phases and other rare region effects, leading rather generically to anomalously slow relaxation in generalized small-world networks. In particular, it is illustrated that Griffiths phases can emerge as the consequence of pure topological heterogeneity if the topological dimension of the network is finite.Comment: 5 pages, 2 figures, proc. of 11th Granada Seminar on Computational Physic

Nucleation of frictional slip: A yielding or a fracture process?

The onset of frictional sliding between contacting bodies under shear load is nucleated by the quasi-static growth of localized slip patches. After reaching a certain critical size, these patches become unstable and continue growing dynamically, eventually causing the sliding of the entire interface. Two different theories have been used to compute the nucleation length of such patches depending on the dominant process driving their growth. If it is only the yielding of contact asperities (large-scale yielding), a stress criterion is applied, based on linear stability analysis, whereas if fracture dominates, an energy criterion is applied, based on fracture mechanics and classical nucleation theory. Both approaches contain important underlying assumptions that are well-suited to describe either one situation or the other. However, what happens in-between is not captured by any of them. In this work, we use numerical simulations to study what is the dominant underlying process driving nucleation for different conditions of heterogeneity and what are the implications for nucleation dynamics and the onset of frictional sliding. We show that large frictional heterogeneities enable a transition from a yielding-driven nucleation phase to a fracture-driven one. This transition occurs only above a certain level of heterogeneity and can either be quasi-static (stable) or dynamic (unstable), depending on the correlation length of frictional strength along the interface and the difference in strength between the strongest and the weakest point (the amplitude). Unstable transitions generate localized dynamic slip events, whose magnitude increases with higher correlation length and decreases with larger amplitude. Our work sheds new light on the role of heterogeneity and fracture in the nucleation of frictional slip, bridging the gap between the two main governing theories for nucleation.Comment: 20 pages, 5 figure

La política de empleo de la unión europea

Nadie duda que la política social jugará un papel importante en el futuro de la Unión Europea, si la idea del mercado único prevalece sobre la Europa de los ciudadanos. En cualquier caso, el problema del empleo ha estado presente desde los origenes de la Comunidad Económica Europea pero como un problema menor. Actualmente, ha llegado a ser un factor importante en la formación de la política económica general. Este estudio muestra un análisis crítico de las políticas comunitarias de empleo. Se estudian tres períodos diferentes: 1) los antecedentes de las políticas de empleo en la Comunidad que terminaría con el Tratado de Maastricht, el cual establece como objetivo promover un mayor nivel de empleo; 2) un segundo período en el cual el empleo es una prioridad en la construcción de una Europa integrada: el Tratado de la Unión; 3) nuevas acciones y procesos comunitarios para el empleo posteriores al Tratado de Amsterdam.________________________________It is difficult to believe that social policies will play an important part in the future in Europe, if the idea of the Europe of the market prevails on the Europe of the citizens. Nevertheless, the employment problem was present since the beginning of the European Economic Community, although as a minor problem. At present, it has become an important factor in the definition of the general economic policy. This paper presents a critical analysis of the Employment Community Policies. Three different periods are presented: l) the old employment policy in the Community that ends with the Maastricht Treaty that establishes the objective of promoting a higher level of employment; 2) a second period in which employment is a priority in order to build an Integrated Europe: The Union Treaty; and 3) new Community actions and processes for employment following Amsterdam Treaty

Estudio de las condiciones de agitación por oleaje en un puerto mediante simulación numérica

Se describe una aplicación del sistema computacional DIFRAC para estudiar la s condiciones de agitación por oleaje dentro de un puerto, teniendo en cuenta el efecto combinado de difracción, refracción y reflexión de las olas . Se presentan resultados para la amplitud y dirección de propagación del oleaje en su interior y de las condiciones de resonancia en la s distintas dársenas del puerto .Peer Reviewe

Estudio de las condiciones de agitación por oleaje en un puerto mediante simulación numérica

Se describe una aplicación del sistema computacional DIFRAC para estudiar la s condiciones de agitación por oleaje dentro de un puerto, teniendo en cuenta el efecto combinado de difracción, refracción y reflexión de las olas . Se presentan resultados para la amplitud y dirección de propagación del oleaje en su interior y de las condiciones de resonancia en la s distintas dársenas del puerto .Peer Reviewe

Bayesian network learning algorithms using structural restrictions

The use of several types of structural restrictions within algorithms for learning Bayesian networks is considered. These restrictions may codify expert knowledge in a given domain, in such a way that a Bayesian network representing this domain should satisfy them. The main goal of this paper is to study whether the algorithms for automatically learning the structure of a Bayesian network from data can obtain better results by using this prior knowledge. Three types of restrictions are formally defined: existence of arcs and/or edges, absence of arcs and/or edges, and ordering restrictions. We analyze the possible interactions between these types of restrictions and also how the restrictions can be managed within Bayesian network learning algorithms based on both the score + search and conditional independence paradigms. Then we particularize our study to two classical learning algorithms: a local search algorithm guided by a scoring function, with the operators of arc addition, arc removal and arc reversal, and the PC algorithm. We also carry out experiments using these two algorithms on several data sets.Spanish Junta de Comunidades de Castilla-La Mancha and Ministerio Educación y Ciencia Projects PBC-02-002 and TIN2004- 06204-C03-0

Cytochrome c: Surfing Off of the Mitochondrial Membrane on the Tops of Complexes III and IV

The proper arrangement of protein components within the respiratory electron transport chain is nowadays a matter of intense debate, since altering it leads to cell aging and other related pathologies. Here, we discuss three current views-the so-called solid, fluid and plasticity models-which describe the organization of the main membrane-embedded mitochondrial protein complexes and the key elements that regulate and/or facilitate supercomplex assembly. The soluble electron carrier cytochrome c has recently emerged as an essential factor in the assembly and function of respiratory supercomplexes. In fact, a 'restricted diffusion pathway' mechanism for electron transfer between complexes III and IV has been proposed based on the secondary, distal binding sites for cytochrome c at its two membrane partners recently discovered. This channeling pathway facilitates the surfing of cytochrome c on both respiratory complexes, thereby tuning the efficiency of oxidative phosphorylation and diminishing the production of reactive oxygen species. The well-documented post-translational modifications of cytochrome c could further contribute to the rapid adjustment of electron flow in response to changing cellular conditions.Spanish Ministry of Economy and Competitiveness (BFU2015-71017/BMC MINECO/FEDER and PGC2018-096049-B-I00 BIO/BMC MICINN/FEDER, EU

Polypill in cardiovascular disease prevention: recent advances.

Triple therapy with lipid‑lowering, antihypertensive, and antiplatelet agents reduces the risk of recurrent cardiovascular fatal and nonfatal events, cardiovascular mortality, and total mortality in secondary prevention. In real life, however, effective implementation of these optimal treatments both in primary and secondary prevention is low, and thus their contribution to cardiovascular prevention is much lower than it could be, based on research data. One of the main barriers to the adequate implementation of these strategies is low adherence to the elevated number of pills, as adherence is adversely affected by the complexity of the prescribed treatment regimen, and can be considerably improved by treatment simplification. This review updates the findings provided by recent epidemiological and clinical studies favoring a polypill‑based approach to cardiovascular prevention. The increased prevalence of patients with multiple cardiovascular risk factors and comorbidities provides the rationale for a therapeutic strategy based on a combination of drugs against different risk factors in a single pill. Pharmacologic studies have demonstrated that different cardiovascular drugs can be combined in a single pill with no loss of their individual efficacy, and this favors adherence to and persistence of treatment, as well as multiple risk factor control. Recently, a randomized clinical trial SECURE (Secondary Prevention of Cardiovascular Disease in the Elderly) has shown a significant, 30% reduction in cardiovascular events, and a 33% reduction in cardiovascular death in patients after myocardial infarction treated with a polypill, as compared with usual care, thus supporting the polypill use as an integral part of any cardiovascular prevention strategy.S