Power accretion in social systems

We consider a model of power distribution in a social system where a set of agents plays a simple game on a graph: The probability of winning each round is proportional to the agent’s current power, and the winner gets more power as a result. We show that when the agents are distributed on simple one-dimensional and two-dimensional networks, inequality grows naturally up to a certain stationary value characterized by a clear division between a higher and a lower class of agents. High class agents are separated by one or several lower class agents which serve as a geometrical barrier preventing further flow of power between them. Moreover, we consider the effect of redistributive mechanisms, such as proportional (nonprogressive) taxation. Sufficient taxation will induce a sharp transition towards a more equal society, and we argue that the critical taxation level is uniquely determined by the system geometry. Interestingly, we find that the roughness and Shannon entropy of the power distributions are a very useful complement to the standard measures of inequality, such as the Gini index and the Lorenz curveWe acknowledge financial support from the Spanish Government through Grants No. FIS2015-69167-C2-1-P, No. FIS2015-66020-C2- 1-P, and No. PGC2018-094763-B-I0

Reconstruction of the second layer of Ag on Pt(111)

The reconstruction of an Ag monolayer on Ag/Pt(111) is analyzed theoretically, employing a vertically extended Frenkel-Kontorova model whose parameters are derived from density functional theory. Energy minimization is carried out using simulated quantum annealing techniques. Our results are compatible with the STM experiments, where a striped pattern is initially found which transforms into a triangular reconstruction upon annealing. In our model we recognize the first structure as a metastable state, while the second one is the true energy minimum

Current and Evolving Models of Peer Review

New models of scientific publishing and new ways of practicing peer review have injected a recent dynamism into the scholarly communication system. In this article, we delineate the context of the traditional peer review model, reflect upon some of the first experiences with open peer review and forecast some of the challenges that new models for peer review will have to meet. Our findings suggest that the peer review function has the potential to be divorced from the journal system, so that the responsibility to judge the significance of a paper may no longer fall exclusively to formal reviewers, but may be assessed by the whole readership community

Comparative genetic analysis of flowering time adaptation in legumes

Weller, J. L. et al.- Resumen de la comunicación oral presentada en la "8th International Conference on Legume Genetics and Genomics (ICLGG)", que tuvo lugar en Siófok, Hungría, entre el 18 y el 22 de septiembre de 2017.A better understanding of flowering genes in legume crops will be valuable in understanding their prehistoric expansion from regions of initial domestication, in breeding for new environments and in accessing wider genetic diversity present in wild crop relatives. We are using a comparative approach to explore the genetic network controlling flowering time adaptation in a number of legume species. In addition to the use of induced mutants in pea (Pisum sativum) and barrel medic (Medicago truncatula), recent work has focused on characterization of natural variation in crop species including pea, lentil (Lens culinaris) and chickpea (Cicer arietinum). We have performed comparative phylogenetic analyses of many of the major flowering gene families in legumes, and examined the expression patterns of key genes, including members of the FT family of florigen genes. A positional candidate gene approach has enabled the identification of putative causal genes for major flowering loci and shown a striking conservation in certain genomic regions conferring flowering time adaptation across several species. Evidence on the molecular and physiological basis for adaptive changes at these loci will be presented and possible reasons for their prominence will be discussed.Peer reviewe

Building an adiabatic quantum computer simulation in the classroom

We present a didactic introduction to adiabatic quantum computation (AQC) via the explicit construction of a classical simulator of quantum computers. This constitutes a suitable route to introduce several important concepts for advanced undergraduates in physics: quantum many-body systems, quantum phase transitions, disordered systems, spin-glasses, and computational complexity theory. (C) 2018 American Association of Physics Teachers.The authors want to acknowledge the faculty and students of the Facultad de Informática of UCM (Madrid) for their kind invitation to deliver this crash course, particularly to I. Rodríguez-Laguna and N. Martí. The authors would also like to thank G. Sierra for very useful comments on the manuscript. This work was funded by the Spanish government through Grant Nos. FIS2015-69167-C2-1-P and FIS2015-66020-C2-1-