Vortices in a rotating BEC under extreme elongation

We investigate a non-axisymmetric rotating BEC in a limit of rotation frequency for which the BEC transforms into a quasi-one-dimensional system. We compute the vortex lattice wavefunction by minimizing the Gross-Pitaevskii energy functional in the lowest Landau level approximation for different confinement potentials. The condensate typically presents a changing number of vortex rows as a function of the interaction strength or rotation-confinement ratio. More specifically, the vortex lattices can be classified into two classes according to their symmetry with respect to the longitudinal axis. These two classes correspond to different local minima of the energy functional and evolve independently as a function of the various parameters.Comment: 8 pages, 12 figure

Rich do not rise early: Spatio-temporal patterns in the mobility networks of different socio-economic classes

We analyse the urban mobility in the cities of Medellín and Manizales (Colombia). Each city is represented by six mobility networks, each one encoding the origin-destination trips performed by a subset of the population corresponding to a particular socio-economic status. The nodes of each network are the different urban locations whereas links account for the existence of a trip between two different areas of the city. We study the main structural properties of these mobility networks by focusing on their spatio-temporal patterns. Our goal is to relate these patterns with the partition into six socio-economic compartments of these two societies. Our results show that spatial and temporal patterns vary across these socio-economic groups. In particular, the two datasets show that as wealth increases the early-morning activity is delayed, the midday peak becomes smoother and the spatial distribution of trips becomes more localized

Critical fields for vortex expulsion from narrow superconducting strips

We calculate the critical magnetic fields for vortex expulsion for an infinitely long superconducting strip, using the Ginzburg-Landau formalism. Two critical fields can be defined associated with the disappearance of either the energetic stability or metastability of vortices in the center of the strip for decreasing magnetic fields. We compare the theoretical predictions for the critical fields in the London formalism with ours and with recently published experimental results. As expected, for narrow strips our results reproduce better the experimental findings.Comment: 5 pages, 5 figure

Explosive Contagion in Networks.

The spread of social phenomena such as behaviors, ideas or products is an ubiquitous but remarkably complex phenomenon. A successful avenue to study the spread of social phenomena relies on epidemic models by establishing analogies between the transmission of social phenomena and infectious diseases. Such models typically assume simple social interactions restricted to pairs of individuals; effects of the context are often neglected. Here we show that local synergistic effects associated with acquaintances of pairs of individuals can have striking consequences on the spread of social phenomena at large scales. The most interesting predictions are found for a scenario in which the contagion ability of a spreader decreases with the number of ignorant individuals surrounding the target ignorant. This mechanism mimics ubiquitous situations in which the willingness of individuals to adopt a new product depends not only on the intrinsic value of the product but also on whether his acquaintances will adopt this product or not. In these situations, we show that the typically smooth (second order) transitions towards large social contagion become explosive (first order). The proposed synergistic mechanisms therefore explain why ideas, rumours or products can suddenly and sometimes unexpectedly catch on

Propuesta conceptual de categoría empresarial de conservación - Informe final

Existen distintos mecanismos para proteger los recursos naturales a través de iniciativas empresariales. Uno de ellos corresponde al establecimiento de áreas de conservación con o sin reconocimiento del Estado, en los que en algunos casos, además de la preservación, también se desarrollan prácticas productivas y extractivistas que permitan un aprovechamiento sostenible de los recursos naturales. De acuerdo con lo dispuesto en la legislación ambiental, el análisis de información especializada publicada, literatura gris, así como de información obtenida a través diversas entrevistas, debates guiados y encuestas anónimas con actores clave del sector empresarial y público encargado de las áreas protegidas del país, identificamos los principales desafíos, motivos, beneficios y amenazas que encuentran las empresas para la inversión de recursos en la protección de la biodiversidad, puntualmente mediante el establecimiento de áreas de conservación. Por otra parte y a partir del anterior análisis, presentamos una ruta de trabajo o árbol de decisión con los mecanismos y estrategias, que le permiten a cualquier empresario realizar inversiones voluntarias u obligatorias para la protección de los recursos naturales. Finalmente, proponemos algunas consideraciones para diferenciar el registro voluntario de un área de conservación de inciativa empresarial. Esperando que con esta información, el sector empresarial asuma un rol proactivo e innovador, para que reconozca en la protección de los recursos naturales, en especial mediante el registro de áreas naturales protegidas, uno de los pilares de sus estrategias y políticas de sostenibilidad; acciones que sin duda fortalecerán el SINAP de uno de los países con mayor diversidad biológica del planeta.Bogotá, Colombi

Catalysing sustainable fuel and chemical synthesis

Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from such combustible carbon, are driving academic and commercial research into new sustainable routes to fuel and chemicals. The quest for such sustainable resources to meet the demands of a rapidly rising global population represents one of this century’s grand challenges. Here, we discuss catalytic solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels, and oxygenated organic molecules for the manufacture of fine and speciality chemicals to meet future societal demands

Self-organized division of cognitive labor

A menudo, los miembros de un grupo se benefician al dividir la tarea del grupo en componentes separados, donde cada miembro especializa su rol para lograr solo uno de los componentes. Si bien este fenómeno de división del trabajo se ha observado con respecto al trabajo manual y cognitivo, no existe una comprensión clara de los mecanismos cognitivos que permiten su aparición, especialmente cuando existen múltiples divisiones posibles y la comunicación es limitada. De hecho, la maximización de la utilidad esperada a menudo no diferencia entre formas alternativas en las que los individuos podrían dividir el trabajo. Desarrollamos un juego iterativo de dos personas en el que hay múltiples formas de dividir el trabajo, pero en el que no es posible negociar explícitamente una división. Implementamos el juego como una tarea experimental humana y como un modelo computacional. Nuestros resultados muestran que la mayoría de las díadas humanas pueden terminar el juego con una eficiente división del trabajo. Además, ajustamos nuestro modelo computacional a los datos de comportamiento, lo que nos permitió explicar cómo la similitud percibida entre las acciones de un jugador y los puntos focales de la tarea guió las elecciones de los jugadores de una ronda a la otra, uniendo así la dinámica de grupo y su proceso cognitivo subyacente. Las aplicaciones potenciales de este modelo fuera de la ciencia cognitiva incluyen la mejora de la cooperación en grupos humanos, sistemas de múltiples agentes, así como la colaboración entre humanos y robots.Often members of a group benefit from dividing the group’s task into separate compo nents, where each member specializes their role so as to accomplish only one of the com ponents. While this division of labor phenomenon has been observed with respect to both manual and cognitive labor, there is no clear understanding of the cognitive mechanisms allowing for its emergence, especially when there are multiple divisions possible and com munication is limited. Indeed, maximization of expected utility often does not differentiate between alternative ways in which individuals could divide labor. We developed an itera tive two-person game in which there are multiple ways of dividing labor, but in which it is not possible to explicitly negotiate a division. We implemented the game both as a human experimental task and as a computational model. Our results show that the majority of human dyads can finish the game with an efficient division of labor. Moreover, we fitted our computational model to the behavioral data, which allowed us to explain how the per ceived similarity between a player’s actions and the task’s focal points guided the players’ choices from one round to the other, thus bridging the group dynamics and its underlying cognitive process. Potential applications of this model outside cognitive science include the improvement of cooperation in human groups, multi-agent systems, as well as human-robot collaboration