Granadas y adormideras en la cultura ibérica y el contexto del Mediterráneo antiguo

Presentamos en este trabajo un catálogo de imágenes ibéricas sobre distintos soportes materiales, donde se representan granadas y, en menor medida, cápsulas de adormidera. Reflexionaremos sobre el simbolismo de estos motivos del mundo vegetal en el contexto de las manifestaciones culturales del mundo ibérico, teniendo en cuenta la amplia documentación existente en otras culturas del ámbito del Mediterráneo antiguo. ______________________________________________ N ous présentons dans ce travail un catalogue d'images ibériques sur differents supports materiels, oú sont representées des grenades et, dans une moindre mesure, des pavots. Nous réfléchirons sur le symbolisme de ces motifs du monde végétal dans le contexte des manifestations culturelles du monde bérique, sans oublier la large documentation existente dans d'autres cultures de la Méditerrannée ancienne

Simulation of an Optional Strategy in the Prisoner's Dilemma in Spatial and Non-spatial Environments

This paper presents research comparing the effects of different environments on the outcome of an extended Prisoner's Dilemma, in which agents have the option to abstain from playing the game. We consider three different pure strategies: cooperation, defection and abstinence. We adopt an evolutionary game theoretic approach and consider two different environments: the first which imposes no spatial constraints and the second in which agents are placed on a lattice grid. We analyse the performance of the three strategies as we vary the loner's payoff in both structured and unstructured environments. Furthermore we also present the results of simulations which identify scenarios in which cooperative clusters of agents emerge and persist in both environments.Comment: 12 pages, 8 figures. International Conference on the Simulation of Adaptive Behavio

New approaches to the synthesis of pyridinium N-heteroarylaminides

Different substituted pyridinium N-heteroarylaminides have been prepared in one step from N-aminopyridinium iodide and the corresponding heteroaryl halide by two alternative routes. The use of Pd catalysis allowed the easy preparation of products from the less reactive haloheterocycles. The use of water as a solvent in conjunction with microwave heating dramatically diminishes the reaction time without having an adverse effect on reaction yields.Universidad de Alcal

Pyridinium N-heteroarylaminides: synthesis of N-heteroaryltetramines based on 1,6-bis(phenoxy)hexane and 1,3-bis(phenoxymethyl)benzene

The synthesis of a set of new N-heteroaryltetramines is reported. A regioselective alkylation on the N-exo nitrogen of pyridinium N-(heteroaryl)aminide with the corresponding tetrabromo compounds, followed by a clean N–N bond reduction of the corresponding tetra-salts, allowed an easy and general method to obtain N,N′,N″,N‴-tetrakis(2-heteroaryl)tetramines.Ministerio de Educación y Cienci

Anotaciones acerca del espacio y la identidad

Al hablar de "La situación en Colombia" se menciona implícitamente una nación y un territorio. Sin embargo, a la hora de hacerse cuestionamientos se recalca la palabra "situación", sin darse cuenta que el sentido y el significado de nación es un proyecto que ha fracasado. En ocasiones, lo que se pretende es solucionar una "situación" a la deriva, una situación sin territorio, una situación aislada. Así pues, el propósito de este artículo es analizar el espacio en relación a la construcción de..

Optically-enhanced performance of polymer solar cells with low concentration of gold nanorods in the anodic buffer layer

In this work, the effect of gold nanorods on the performance of poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C61-butyric-acid-methyl-ester bulk heterojunction solar cells was investigated. Gold nanorods were introduced into the anodic buffer layer by simply blending them with the solution of poly(3,4-ethyl enedioxythiophene):poly(styrenesulfonate). Even with a fairly low density of the nanorods, the resulting devices showed a remarkable 21.3% enhancement in the power conversion efficiency and a 13% enlargement in the short circuit current. By examining the absorbance profiles of active films made with different conditions,\ud such enhancements can be related to the localized transverse and longitudinal plasmon resonance modes in the metallic nanoparticles. Gold nanorods helped as well in reducing the device series resistance by up to 36%, which also contributed to the global enhancement in the efficiency

Suzuki reaction on pyridinium N-(5-bromoheteroar-2-yl)aminides

The reactivity of substituted pyridinium N-(2'-azinyl)aminides in Suzuki-Miyaura cross-coupling reaction is reported. The reaction proceeds in good yield employing Cs2CO3 as base, and producing substitution on the neg. charged moiety. [on SciFinder(R)]We wish to thank the Comisión Interministerial de Ciencia y Tecnología (CICYT-BQU2001-1508) for financial support, and the Ministerio de Educación y Cultura (MEC) for a studentship (M.J.R.)

Entanglement in holographic dark energy models

We study a process of equilibration of holographic dark energy (HDE) with the cosmic horizon around the dark-energy dominated epoch. This process is characterized by a huge amount of information conveyed across the horizon, filling thereby a large gap in entropy between the system on the brink of experiencing a sudden collapse to a black hole and the black hole itself. At the same time, even in the absence of interaction between dark matter and dark energy, such a process marks a strong jump in the entanglement entropy, measuring the quantum-mechanical correlations between the horizon and its interior. Although the effective quantum field theory (QFT) with a peculiar relationship between the UV and IR cutoffs, a framework underlying all HDE models, may formally account for such a huge shift in the number of distinct quantum states, we show that the scope of such a framework becomes tremendously restricted, devoiding it virtually any application in other cosmological epochs or particle-physics phenomena. The problem of negative entropies for the non-phantom stuff is also discussed.Comment: 10 pages, version to appear in PL

An easy preparation of pyridinium N-heteroarylaminides

A synthesis of substituted pyridinium N-heteroarylaminides, e.g., I, is reported. Heteroaryl chlorides underwent nucleophilic substitution with N-aminopyridinium iodide to give the corresponding substituted pyridinium N-heteroarylaminides in good yields. [on SciFinder(R)]Differently substituted pyridinium N-heteroarylaminides have been prepared in one step with good yield from N-aminopyridinium iodide and the corresponding heteroaryl chloride.The authors wish to thank the Ministerio de Ciencia y Tecnología (projects CICYT-2FD97-1248 and BQU2001-1508) for financial support, and the Ministerio de Educación y Cultura for a studenship (M.J.R.)

Pyridinium-N-(2-Pyridyl)aminides: a selective approach to substituted 2-aminopyridines

Differently substituted 2-aminopyridines have been prepared in two steps from pyridinium-N-(2-pyridyl)aminide, by reaction with the corresponding electrophiles and reduction of the N-N bond.Ministerio de Educación y Cienci