The Berry phase and the pump flux in stochastic chemical kinetics

We study a classical two-state stochastic system in a sea of substrates and products (absorbing states), which can be interpreted as a single Michaelis-Menten catalyzing enzyme or as a channel on a cell surface. We introduce a novel general method and use it to derive the expression for the full counting statistics of transitions among the absorbing states. For the evolution of the system under a periodic perturbation of the kinetic rates, the latter contains a term with a purely geometrical (the Berry phase) interpretation. This term gives rise to a pump current between the absorbing states, which is due entirely to the stochastic nature of the system. We calculate the first two cumulants of this current, and we argue that it is observable experimentally

Improved Prediction of Heuristic Configuration for Queue Priority on FaCt++ Semantic Reasoner

With the adoption of the semantic web, interest in technologies and theory about formalizing the representation of knowledge, and automated reasoning has increased. Ontologies are concrete instances of knowledge representation and logical reasoners play an important role during the creation of ontologies, since they can find logical errors during design. One of these logical reasoners is FaCt++, which implements an optimized analytical tableaux algorithm. The specific implementation of tableaux in FaCt++ includes a set of priority queues to handle and expand the different operators that can be found during reasoning, these queues have an order for applying the different operators, which in this work will be referred as priority configurations. It was proved by the authors of FaCt++ that there is not a single priority configuration that has the best performance for all types of ontologies. Recently it was suggested that machine learning models can be successfully applied to find the best heuristic for every specific ontology. In this work is presented the process to build a machine learning model to find the best priority configuration for every ontology in detail. The model proposed in this work uses fewer features than the one shown previously and creates a simpler model with similar or better accuracy on the resulting classification.ITESO, A. C

Mechanism of Alkyl Migration in Diorganomagnesium 2,6-Bis(imino)pyridine Complexes: Formation of Grignard-Type Complexes with Square-Planar Mg(II) Centers

Dialkylmagnesium compounds [MgR2L2] (R = n-Bu, L = none or R = Bn, L = THF) react with 2,6-bis(imino)pyridines (BIP) to afford different types of Mg(II) alkyl complexes, depending on the nature of R. For R = n-Bu, thermally stable products resulting from selective alkyl transfer to the pyridine nitrogen (N1) atom are obtained. However, NMR studies showed that the reaction of [Mg(Bn)2THF2] with iPrBIP at −65 °C leads to a thermally unstable product arising from benzyl migration to position C2 in the pyridine ring. Above +5 °C, this compound rearranges, cleanly yielding a mixture of two isomeric complexes, in which the benzyl group has migrated to positions C3 or C4 of the central ring, respectively. Similar isomeric mixtures were obtained when [Mg(Bn)2THF2] was reacted with iPrBIP or MesBIP at room temperature. Such mixtures are thermally stable below 80 °C, but at this temperature, the 3-benzyl isomer converts into the thermodynamically favored 4-benzyl product, albeit not quantitatively. An alternate route was devised for the selective syntheses of the latter type of compounds. The X-ray diffraction structure of one of them provided an unusual example of a square-planar alkylmagnesium(II) center.Ministerio de Economía e Innovación CTQ2015-68978-

Amor, bioética y ecología en régimen cristiano.

En este breve estudio el Autor se enfrenta con dos saberes de plena actualidad: Bioética y Ecoética. Respecto al primero, intenta mostrar que sólo puede desarrollarse de manera adecuada en el marco de una moral objetiva y de carácter normativo, de orientación antropológica y fundamentación metafísica. En cuanto al segundo, analiza cómo responde hoy la doctrina social de la Iglesia al problema ecológico proponiendo como modelo la figura del “pobre de Asís”. En ambos casos, la virtud teologal del amor es la piedra angular de un edificio que pretende ser digno de quien lo habita, el hombre como ser creado a imagen y semejanza de Dios