Statistical Mechanics of finite arrays of coupled bistable elements

We discuss the equilibrium of a single collective variable characterizing a finite set of coupled, noisy, bistable systems as the noise strength, the size and the coupling parameter are varied. We identify distinct regions in parameter space. The results obtained in prior works in the asymptotic infinite size limit are significantly different from the finite size results. A procedure to construct approximate 1-dimensional Langevin equation is adopted. This equation provides a useful tool to understand the collective behavior even in the presence of an external driving force

Redox-dependent and redox-independent functions of Caenorhabditis elegans thioredoxin 1

Thioredoxins (TRX) are traditionally considered as enzymes catalyzing redox reactions. However, redox-independent functions of thioredoxins have been described in different organisms, although the underlying molecular mechanisms are yet unknown. We report here the characterization of the first generated endogenous redox-inactive thioredoxin in an animal model, the TRX-1 in the nematode Caenorhabditis elegans. We find that TRX-1 dually regulates the formation of an endurance larval stage (dauer) by interacting with the insulin pathway in a redox-independent manner and the cGMP pathway in a redox-dependent manner. Moreover, the requirement of TRX-1 for the extended longevity of worms with compromised insulin signalling or under calorie restriction relies on TRX-1 redox activity. In contrast, the nuclear translocation of the SKN-1 transcription factor and increased LIPS-6 protein levels in the intestine upon trx-1 deficiency are strictly redox-independent. Finally, we identify a novel function of C. elegans TRX-1 in male food-leaving behaviour that is redox-dependent. Taken together, our results position C. elegans as an ideal model to gain mechanistic insight into the redox-independent functions of metazoan thioredoxins, overcoming the limitations imposed by the embryonic lethal phenotypes of thioredoxin mutants in higher organisms.NIH Office of Research Infrastructure P40 OD010440Spanish Ministry of Economy and Competitiveness BFU2015- 64408-PFondo Social Europeo BFU2015- 64408-PNational Institute of Allergy and Infectious Diseases of the National Institutes of Health R01AI07640

Gain in Stochastic Resonance: Precise Numerics versus Linear Response Theory beyond the Two-Mode Approximation

In the context of the phenomenon of Stochastic Resonance (SR) we study the correlation function, the signal-to-noise ratio (SNR) and the ratio of output over input SNR, i.e. the gain, which is associated to the nonlinear response of a bistable system driven by time-periodic forces and white Gaussian noise. These quantifiers for SR are evaluated using the techniques of Linear Response Theory (LRT) beyond the usually employed two-mode approximation scheme. We analytically demonstrate within such an extended LRT description that the gain can indeed not exceed unity. We implement an efficient algorithm, based on work by Greenside and Helfand (detailed in the Appendix), to integrate the driven Langevin equation over a wide range of parameter values. The predictions of LRT are carefully tested against the results obtained from numerical solutions of the corresponding Langevin equation over a wide range of parameter values. We further present an accurate procedure to evaluate the distinct contributions of the coherent and incoherent parts of the correlation function to the SNR and the gain. As a main result we show for subthreshold driving that both, the correlation function and the SNR can deviate substantially from the predictions of LRT and yet, the gain can be either larger or smaller than unity. In particular, we find that the gain can exceed unity in the strongly nonlinear regime which is characterized by weak noise and very slow multifrequency subthreshold input signals with a small duty cycle. This latter result is in agreement with recent analogue simulation results by Gingl et al. in Refs. [18, 19].Comment: 22 pages, 5 eps figures, submitted to PR

Pt(II) coordination complexes as visible light photocatalysts for the oxidation of sulfides using batch and flow processes

A new catalytic system for the photooxidation of sulfides based on Pt(ii) complexes is presented. The catalyst is capable of oxidizing a large number of sulfides containing aryl, alkyl, allyl, benzyl, as well as more complex structures such as heterocycles and methionine amino acid, with complete chemoselectivity. In addition, the first sulfur oxidation in a continuous flow process has been developedJ. A. would also like to thank the MICINN for their ‘Ramón y Cajal’ contract and the European Research Council (ERC-CG, contract number 647550

Caracterización de la capa límite en Madrid en situaciones de estabilidad atmosférica

Ponencia presentada en: XX Jornadas Científicas de la AME, IX Encuentro Hispano Luso de Meteorología y el XII Congreso Latinoamericano e Ibérico de Meteorología celebrado en Zaragoza, del 5 al 7 de mayo de 2008

Singlet-triplet energy gaps modulation of Diindeno [1,2-b: 1’2’-g] anthracene molecular family

Nowadays there is a large interest in organic materials based on diradical polycyclic aromatic hydrocarbons (PAHs) due to their unique properties, such as narrow frontier-orbital energy gaps, strong absorption in the visible spectrum, etc. However, the inherent diradical nature make these compounds with limited chemical stability giving rise to rapid decomposition under ambient conditions thus reducing their practical use. In recent years PAH diradicals that exhibit remarkable stability have been prepared thanks to the description of efficient synthetic routes to access them. One of these remarkable cases is the diindeno [1,2-b: 1’2’-g] anthracene, named as DIAn. DIAn is constituted by antiaromatic segments together with a central pro-aromatic structure. One of the important observable properties of diradicals is the singlet-triplet energy gap, ∆EST, which is intimately connected with the diradical character. The possibility of access to the molecular structure of diradicals is very valuable since properties such as the bond-order or the bond-length alternation of the mentioned moieties reveal the diradical content. Electronic and vibrational spectroscopies are alternative sources of structural information that often compensate the absence of solid-state structures. In this communication, we expand the studies of DIAn by introducing another aspect of the modulation of the ∆EST which concerns with: i) the extension of the terminal benzenes with another fused benzene (i.e., forming terminal napthalenes) and ii) with the isomerization resulting from the fusion topology of these terminal benzenes. We will present a UV-Vis-NIR and Raman spectroscopic study of the new compounds. The variation of the spectra within molecular family will be discussed in connection with the variation of ∆EST and with the diradical character of the new molecules.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Reversible Dimerization/Polymerization of a Janus Diradical Producing Labile CC Bonds and Giant Chromism

En esta comunicación se presenta el estudio espectroscópico y téorico de la dimerización/oligomerización reversible de un birradical derivado de naftoditiofeno el cual en su forma monomérica presenta una intenso color azul mientras que al agregar se muestra incoloro, siendo éstas formas intercambiables gracias a la aplicación de estímulos débiles como presión o temperatura.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech