Highly-efficient noise-assisted energy transport in classical oscillator systems

Photosynthesis is a biological process that involves the highly-efficient transport of energy captured from the sun to a reaction center, where conversion into useful biochemical energy takes place. Even though one can always use a quantum perspective to describe any physical process, since everything follows the laws of Quantum Mechanics, is the use of quantum theory imperative to explain this high efficiency? Making use of the quantum-classical correspondence of electronic energy transfer recently introduced by Eisfeld and Briggs [Phys. Rev. E 85, 046118 (2012)], we show here that the highly-efficient noise-assisted energy transport described by Rebentrost et al. [New J. Phys. 11, 033003 (2009)], and Plenio and Huelga [New J. Phys. 10, 113019 (2008)], as the result of the interplay between the quantum coherent evolution of the photosynthetic system and noise introduced by its surrounding environment, it can be found as well in purely classical systems. The wider scope of applicability of the enhancement of energy transfer assisted by noise might open new ways for developing new technologies aimed at enhancing the efficiency of a myriad of energy transfer systems, from information channels in micro-electronic circuits to long-distance high-voltage electrical lines.Comment: 4 pages, 3 figure

A New Characterization of Trivially Perfect Graphs

A graph $G$ is \emph{trivially perfect} if for every induced subgraph the cardinality of the largest set of pairwise nonadjacent vertices (the stability number) $\alpha(G)$ equals the number of (maximal) cliques $m(G)$. We characterize the trivially perfect graphs in terms of vertex-coloring and we extend some definitions to infinite graphs

Educational challenges of emerging risks in cyberspace: foundations of an appropriate strategy for preventing online child victimisation

In just a few years, technological changes have transformed how people interact and communicate with each other, in particular among so-called digital adolescents. The impact of technology on routine activities and mainstream culture has led to an increase in young peoples’ exposure to psychological and criminological risks. As a result of this new psychosocial trend, new educational challenges are appearing and it is becoming more necessary to react to these challenges on the basis of an adequate diagnosis of psychology and pedagogy relating to adolescents. Criminological theories and research have tried to identify risk and protection factors to understand victimisation processes in more depth and improve prevention strategies. In this context, it is necessary to develop educational programs that consider personal, familial, and situational vulnerabilities and weaknesses in order to foster resilient individuals who can successfully confront the risks inherent to cyberspace. By analysing specific forms of cybervictimisation, guidelines based on criminological research and the most frequent victimisation processes will be identified in order to improve design of educational programs focused on parents, educators and potential victims.El avance tecnológico ha transformado en pocos años la forma de interactuar y comunicarse entre las personas, especialmente entre los denominados adolescentes digitales. Su impacto en las actividades cotidianas y en la cultura dominante ha propiciado, asimismo, un incremento en la exposición a riesgos psicológicos y criminológicos por parte de los menores. Ante esta nueva realidad psicosocial, se plantean nuevos retos educacionales que deben partir de un adecuado diagnóstico de la psicología y pedagogía en relación con los adolescentes. Las teorías e investigaciones criminológicas vienen tratando de identificar los factores de riesgo y de protección con la finalidad de comprender con mayor profundidad los procesos de victimización y mejorar las estrategias de prevención. En este contexto, conviene avanzar en programas educativos que tengan en cuenta las carencias y vulnerabilidades personales, familiares y situacionales de los menores, a fin de fomentar el desarrollo de personas resilientes que sepan afrontar con éxito los riesgos que se fraguan y surgen en el ciberespacio. Mediante el análisis de las concretas formas de cibervictimización se pretende señalar algunas pautas basadas en la investigación criminológica y en los procesos de victimización más frecuentes en los entornos en que se desenvuelven los menores, de modo que puedan servir en el diseño de los programas educativos dirigidos a padres, educadores y potenciales víctimas

Coherent delocalization: Views of entanglement in different scenarios

The concept of entanglement was originally introduced to explain correlations existing between two spatially separated systems, that cannot be described using classical ideas. Interestingly, in recent years, it has been shown that similar correlations can be observed when considering different degrees of freedom of a single system, even a classical one. Surprisingly, it has also been suggested that entanglement might be playing a relevant role in certain biological processes, such as the functioning of pigment-proteins that constitute light-harvesting complexes of photosynthetic bacteria. The aim of this work is to show that the presence of entanglement in all of these different scenarios should not be unexpected, once it is realized that the very same mathematical structure can describe all of them. We show this by considering three different, realistic cases in which the only condition for entanglement to exist is that a single excitation is coherently delocalized between the different subsystems that compose the system of interest