Relational symplectic groupoids

This note introduces the construction of relational symplectic groupoids as a way to integrate every Poisson manifold. Examples are provided and the equivalence, in the integrable case, with the usual notion of symplectic groupoid is discussed.Comment: 36 pages, 1 figur

BFKL Pomeron calculus: nucleus-nucleus scattering

In this paper the action of the BFKL Pomeron calculus is re-written in momentum representation, and the equations of motion for nucleus-nucleus collisions are derived, in this representation. We found the semi-classical solutions to these equations, outside of the saturation domain. Inside this domain these equations reduce to the set of delay differential equations, and their asymptotic solutions are derived.Comment: 22pp. 9 figures imn .eps file

Angular momentum evolution in Dark Matter haloes: a study of the Bolshoi and Millennium simulations

We use three different cosmological dark matter simulations to study how the orientation of the angular momentum vector (AM) in dark matter haloes evolve with time. We find that haloes in this kind of simulations are constantly affected by a spurious change of mass, which translates into an artificial change in the orientation of the AM. After removing the haloes affected by artificial mass change, we found that the change in the orientation of the AM vector is correlated with time. The change in its angle and direction (i.e. the angle subtended by the AM vector in two consecutive timesteps) that affect the AM vector has a dependence on the change of mass that affects a halo, the time elapsed in which the change of mass occurs and the halo mass. We create a Monte-Carlo simulation that reproduces the change of angle and direction of the AM vector. We reproduce the angular separation of the AM vector since a look back time of 8.5 Gyrs to today ( $\rm \alpha$) with an accuracy of approximately 0.05 in $\rm cos(\alpha)$. We are releasing this Monte-Carlo simulation together with this publication. We also create a Monte Carlo simulation that reproduces the change of the AM modulus. We find that haloes in denser environments display the most dramatic evolution in their AM direction, as well as haloes with a lower specific AM modulus. These relations could be used to improve the way we follow the AM vector in low-resolution simulations.Comment: Accepted by MNRA

Dephasing-assisted transport in linear triple quantum dots

Environmental noise usually hinders the efficiency of charge transport through coherent quantum systems; an exception is dephasing-assisted transport (DAT). We show that linear triple quantum dots in a transport configuration and subjected to pure dephasing exhibit DAT if the coupling to the drain reservoir exceeds a threshold. DAT occurs for arbitrarily weak dephasing and the enhancement can be directly controlled by the coupling to the drain. Moreover, for specific settings, the enhanced current is accompanied by a reduction in relative shot noise. We identify the quantum Zeno effect and long-distance tunnelling as underlying dynamical processes involved in dephasing-assisted and -suppressed transport. Our analytical results are obtained by using the density matrix formalism and the characteristic polynomial approach to full counting statistics.Comment: To appear in New Journal of Physics, 20 pages, 5 figure

Multiple outflows in the planetary nebula NGC 6058

We present narrow-band [O III]lambda5007 and H-alpha images, as well as long-slit high-resolution echelle spectra of the planetary nebula NGC 6058. Our data reveal that NGC 6058 is a multipolar planetary nebula of about ~45 arcsec in extent and formed by four bipolar outflows that are oriented at different position angles. Assuming homologous expansion for all the structures, and a distance of 3.5 kpc, we obtain polar velocities around ~68 km s^-1 for three of them. The estimated kinematical ages suggest that the three oldest outflows have been ejected in intervals of ~ 1100 and ~ 400 yr during which, the ejection axis has changes its orientation by ~ 60 degrees and ~ 40 degrees, respectively. Although a inner ring-like structure is suggested by the direct images, its kinematics shows that no equatorial ring or toroid exists in the nebula. At the contrary, the long-slit spectra reveal that the ring-like structure corresponds to a fourth outflow that is oriented almost perpendicular to the other three. This fourth outflow is the youngest one and appears to be interacting with the other three, creating a protruding zone that sweeps material in a region almost perpendicular to the major axes of the oldest outflows. This structure also presents two bright arcuate regions along the same direction of the older outflows, and at opposite sides from the central star. From our model, we suggest that NGC 6058 could be anintermediate evolutionary stage between starfish planetary nebulae and multipolar planetary nebula with apparent equatorial lobes

Percepciones de estudiantes sobre el Aprendizaje móvil; la nueva generación de la educación a distancia

Durante años, muchas instituciones y universidades han comenzado a experimentar con los dispositivos móviles en el aprendizaje a través de diferentes proyectos como parte de su metodología de aprendizaje. La experiencia adquirida con el empleo de estrategias y enfoques en la educación a distancia puede facilitar la conceptualización del aprendizaje móvil, así como el desarrollo de aplicaciones para este nuevo medio de aprendizaje. Los dispositivos móviles abren además nuevos caminos para el aprendizaje y una nueva generación para la educación a distancia, y los investigadores conocen estos nuevos caminos para el aprendizaje y oportunidades de llegar a un público más amplio. Este trabajo, muestra los resultados de un grupo de discusión que se llevó a cabo entre 20 estudiantes de licenciatura con el fin de explorar las percepciones, y en general todo aquello que afecta a la interpretación subjetiva de los individuos y su interacción con un fenómeno social como el aprendizaje móvil.During recent years, many institutions and universities have started to experiment with mobile learning through different projects as part of their e-learning methodology. The experience gained with the employment of strategies and approaches within distance education can assist with the conceptualization of mobile learning as well as the development of applications for this new learning medium. The mobile devices open up new paths for learning, and a new generation of distance education, and the Researchers know that the mobile devices open up new paths for learning and opportunities to reach a wider audience. This paper shows a focus group that was conducted amongst 20 degree students in order to explore the student’s perceptions, and in general the individual interpretation and the user's interaction with a social phenomenon like the mobile learning