Ecological Modelling with the Calculus of Wrapped Compartments

The Calculus of Wrapped Compartments is a framework based on stochastic multiset rewriting in a compartmentalised setting originally developed for the modelling and analysis of biological interactions. In this paper, we propose to use this calculus for the description of ecological systems and we provide the modelling guidelines to encode within the calculus some of the main interactions leading ecosystems evolution. As a case study, we model the distribution of height of Croton wagneri, a shrub constituting the endemic predominant species of the dry ecosystem in southern Ecuador. In particular, we consider the plant at different altitude gradients (i.e. at different temperature conditions), to study how it adapts under the effects of global climate change.Comment: A preliminary version of this paper has been presented in CMC13 (LNCS 7762, pp 358-377, 2013

AC Josephson effect in finite-length nanowire junctions with Majorana modes

It has been predicted that superconducting junctions made with topological nanowires hosting Majorana bound states (MBS) exhibit an anomalous 4\pi-periodic Josephson effect. Finding an experimental setup with these unconventional properties poses, however, a serious challenge: for finite-length wires, the equilibrium supercurrents are always 2\pi-periodic as anticrossings of states with the same fermionic parity are possible. We show, however, that the anomaly survives in the transient regime of the ac Josephson effect. Transients are moreover protected against decay by quasiparticle poisoning as a consequence of the quantum Zeno effect, which fixes the parity of Majorana qubits. The resulting long-lived ac Josephson transients may be effectively used to detect MBS.Comment: 9 pages, 4 figures, published version (with supplementary material

Transport spectroscopy of NS nanowire junctions with Majorana fermions

We investigate transport though normal-superconductor nanowire junctions in the presence of spin-orbit coupling and magnetic field. As the Zeeman field crosses the critical bulk value B_c of the topological transition, a Majorana bound state (MBS) is formed, giving rise to a sharp zero-bias anomaly (ZBA) in the tunneling differential conductance. We identify novel features beyond this picture in wires with inhomogeneous depletion, like the appearance of two MBSs inside a long depleted region for B<B_c. The resulting ZBA is in most cases weakly split and may coexist with Andreev bound states near zero energy. The ZBA may appear without evidence of a topological gap closing. This latter aspect is more evident in the multiband case and stems from a smooth pinch-off barrier. Most of these features are in qualitative agreement with recent experiments [Mourik et al, Science 336, 1003 (2012)]. We also discuss the rich phenomenology of the problem in other regimes which remain experimentally unexplored.Comment: 10 pages, 12 figures. Published version, supplementary material include

Intergenerational Mobility of Income: The Case of Chile 1996-2006

Using the largest household panel data available in Chile we investigate intergenerational mobility of income during the decade 1996-2006. Following recent literature we control our estimates by time-series variation in intergenerational mobility. In addition, we control for sample selection following new weight adjusting methods proposed for intergenerational mobility analysis using longitudinal data. Our results indicate low income mobility compared with developing countries and that income elasticities are higher for men. Furthermore, a cohort analysis suggests that intergenerational mobility decreased with time.Chile, income mobility, intergenerational mobility

Inside-outside money competition

We study how competition from privately supplied currency substitutes affects monetary equilibria. Whenever currency is inefficiently provided, inside money competition plays a disciplinary role by providing an upper bound on equilibrium inflation rates. Furthermore, if "inside monies" can be produced at a sufficiently low cost, outside money is driven out of circulation. Whenever a 'benevolent' government can commit to its fiscal policy, sequential monetary policy is efficient and inside money competition plays no role.Money ; Payment systems

Network unfairness in dragonfly topologies

Dragonfly networks arrange network routers in a two-level hierarchy, providing a competitive cost-performance solution for large systems. Non-minimal adaptive routing (adaptive misrouting) is employed to fully exploit the path diversity and increase the performance under adversarial traffic patterns. Network fairness issues arise in the dragonfly for several combinations of traffic pattern, global misrouting and traffic prioritization policy. Such unfairness prevents a balanced use of the resources across the network nodes and degrades severely the performance of any application running on an affected node. This paper reviews the main causes behind network unfairness in dragonflies, including a new adversarial traffic pattern which can easily occur in actual systems and congests all the global output links of a single router. A solution for the observed unfairness is evaluated using age-based arbitration. Results show that age-based arbitration mitigates fairness issues, especially when using in-transit adaptive routing. However, when using source adaptive routing, the saturation of the new traffic pattern interferes with the mechanisms employed to detect remote congestion, and the problem grows with the network size. This makes source adaptive routing in dragonflies based on remote notifications prone to reduced performance, even when using age-based arbitration.Peer ReviewedPostprint (author's final draft

Role of Oxidative Stress as a Novel Therapeutic Target in Myocardial Injury Due to Ischemia/Reperfusion in Patients with Acute Myocardial Infarction

The most effective therapeutic intervention for reducing infarct size and improving outcomes in patients with acute myocardial infarction is the thrombolytic therapy or percutaneous coronary angioplasty. However, this process itself can generate ischemia-reperfusion injury that can be responsible for up to 50% of the final infarct size. Considering oxidative stress as the main damaging agent in this pathology, it has been postulated that reinforcing antioxidant defenses could improve cardiac function. However, up to date clinical trials based on monotherapies have been consistent in the favorable results. In this review the pathophysiological mechanisms of myocardial injury due to ischemia/reperfusion in patients undergoing percutaneous coronary angioplasty are updated. In addition, new therapeutic alternatives for cardioprotection in this population, are explored, with emphasis in the combined therapy as a novel antioxidant treatment for this myocardial injury

Oscillatory regimes in cardiac cells determined by the calcium concentration

Spatial and temporal calcium oscillations within cardiac cells can induce spontaneous excitations alien to the normal pace of the heart, favouring the appearance of arrhythmias. In this work we will study the dynamics of this oscillations and the main factors that cause them using multiple mathematical models with the objective of providing insight into the causes of this disorders2021/202