Electron-Phonon Interactions in C28_{28}-derived Molecular Solids

We present {\it ab initio} density-functional calculations of molecular solids formed from C$_{28}$-derived closed-shell fullerenes. Solid C$_{28}$H$_4$ is found to bind weakly and exhibits many of the electronic structure features of solid C$_{60}$ with an enhanced electron-phonon interaction potential. We show that chemical doping of this structure is feasible, albeit more restrictive than its C$_{60}$ counterpart, with an estimated superconducting transition temperature exceeding those of the alkali-doped C$_{60}$ solids.Comment: Lower quality postscript file for Figure 1 is used in the manuscript in order to meet submission quota for pre-print server. Higher quality postscript file available from author: [email protected] This article has been updated to reflect changes incorporated during the peer review process. It is published in PRB 70, 140504(R) 200

Information fusion from multiple databases using meta-association rules

Nowadays, data volume, distribution, and volatility make it difficult to search global patterns by applying traditional Data Mining techniques. In the case of data in a distributed environment, sometimes a local analysis of each dataset separately is adequate but some other times a global decision is needed by the analysis of the entire data. Association rules discovering methods typically require a single uniform dataset and managing with the entire set of distributed data is not possible due to its size. To address the scenarios in which satisfying this requirement is not practical or even feasible, we propose a new method for fusing information, in the form of rules, extracted from multiple datasets. The proposed model produces meta-association rules, i.e. rules in which the antecedent or the consequent may contain rules as well, for finding joint correlations among trends found individually in each dataset. In this paper, we describe the formulation and the implementation of two alternative frameworks that obtain, respectively, crisp meta-rules and fuzzy meta-rules. We compare our proposal with the information obtained when the datasets are not separated, in order to see the main differences between traditional association rules and meta-association rules. We also compare crisp and fuzzy methods for meta-association rule mining, observing that the fuzzy approach offers several advantages: it is more accurate since it incorporates the strength or validity of the previous information, produces a more manageable set of rules for human inspection, and allows the incorporation of contextual information to the mining process expressed in a more human-friendly format

2D chiral structures in quinoline mixed Langmuir monolayers.

Chirality at interfaces is a relevant topic in nanoscience, as well as a key point for prebiotic chemistry. Mixed Langmuir monolayers, composed of the anionic phospholipid dimyristoyl phosphatidic acid (DMPA) and the cationic amphiphilic quinoline derivative 2-methyl-1-octadecylquinoline (MQ) have been built at the air-water interface. Both DMPA and MQ molecules are miscible, thus the equimolar mixture yields homogeneous monolayers completely. Chiral domains have been formed by this monolayer and observed in situ by Brewster angle microscopy (BAM). These chiral domains display a large array of shapes and sizes. The chirality of the monolayers has been confirmed by circular dichroism spectroscopy. The ordered aggregation of the quinoline group into large chiral supramolecular structures is proposed as the molecular origin of the observed chirality. Theoretical simulations using molecular mechanics confirm the strong trend of the quinoline group to form chiral aggregates. The great diversity in the size and shape of the chiral domains has been found to be strongly influenced by the competition between two nuclei growth mechanisms. An experimental procedure allowing a minimized growth through one of these mechanism is proposed, achieving a homogeneous distribution of ring-shaped domains. An overshoot in the pi-A isotherms of this mixed monolayer appears at an intermediate surface pressure. This overshoot is interpreted as being due to the large difference between the surface pressure which starts the nuclei formation, pi(crit) and the superficial pressure in which the nuclei can grow, pi(e). The rather small pi(e) value compared to pi(crit) observed for this system must be attributed to the molecular interactions involved in the mixed monolayer, which facilitate the incorporation of molecules in preformed nuclei

The Interplay between Cytoskeleton and Calcium Dynamics

Cell motility is a complex cellular event that involves reorganization of cytoskeleton. This reorganization encompasses the transient polarization of the cell to facilitate the plasma membrane ruffling, a rearrangement of cortical actin cytoskeleton required for the development of cellular protrusions. It is known that extracellular Ca2+ influx is essential for cell migration and for the positive-feedback cycle that maintains leading-edge structures and ruffling activity. The aim of this review is to summarize our knowledge regarding the Ca2+-dependent signaling pathways, Ca2+ transporters and sensors involved in cell migration. Also, we show here reported evidences that support for a crosstalk between Ca2+ transport and the reorganization of the cytoskeleton required for cell migration. In this regard, we will analyze the role of store-operated Ca2+ entry (SOCE) as a modulator of cytoskeleton and cell migration, but also the modulation of this Ca2+ entry pathway by microtubules and the actin cytoskeleton. As a main conclusion, this review will show that data reported in the last years support a role for SOCE in shaping cytoskeleton, but at the same time, SOCE is strongly dependent on cytoskeletal proteins, in an interesting interplay between cytoskeleton and Ca2+ dynamics

Electronic, vibrational, and thermodynamic properties of ZnS (zincblende and rocksalt structure)

We have measured the specific heat of zincblende ZnS for several isotopic compositions and over a broad temperature range (3 to 1100 K). We have compared these results with calculations based on ab initio electronic band structures, performed using both LDA and GGA exchange- correlation functionals. We have compared the lattice dynamics obtained in this manner with experimental data and have calculated the one-phonon and two-phonon densities of states. We have also calculated mode Grueneisen parameters at a number of high symmetry points of the Brillouin zone. The electronic part of our calculations has been used to investigate the effect of the 3d core electrons of zinc on the spin-orbit splitting of the top valence bands. The effect of these core electrons on the band structure of the rock salt modification of ZnS is also discussed.Comment: 33pages, 16 Figures, submitted to Phys. Rev.

Qué sabemos de los Aguarás: Experiencias de un taller educativo sobre Cánidos Silvestres (Mburucuyá, Corrientes)

Esta actividad de extensión es resultado de proyectos de investigación que forman  parte de la Estación Biológica de Corrientes (EBCo, MACN-CONICET) para difundir información sobre la biología, ecología y comportamiento de tres especies de cánidos silvestres que coexisten en la provincia de Corrientes: el aguará guazú (Chrysocyon brachyurus), y dos especies más pequeñas, conocidas como aguará chaí Cerdocyon thous y Lycalopex gymnocercus. El objetivo principal fue establecer un vínculo que sensibilice a los participantes sobre cuestiones referentes a la conservación de estas especies y su entorno, a partir del papel que cumplen las mismas en su ambiente permitiendo que los participantes puedan respetar, cuidar y valorar sus recursos naturales. El presente trabajo da a conocer una de las primeras experiencias del taller denominado “¿Qué sabemos de los aguarás?... Valorando nuestras especies nativas” realizado en el Colegio N° 613 “Ada Ramona Turconi, extensión áulica de la misma escuela ubicada en la localidad de Mburucuyá (Corrientes), el día 22 de junio 2016, con siete actividades diferentes. Tanto para los participantes como los integrantes del equipo de trabajo el intercambio ha sido positivo, pues mediante el juego, propuesto como herramienta de transferencia de conocimientos científicos, se obtuvo una participación enriquecedora para los responsables del taller, y llena de interés y buena predisposición por parte de la comunidad educativa de dicha institución escolar.