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

A synergetic combination of neutron scattering, atomistic simulations and theoretical modelling

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0.Trabajo presentado a: QENS/WINS 2014 - 11th International Conference on Quasielastic Neutron Scattering and 6th International Workshop on Inelastic Neutron SpectrometersMotivated by the proposition of a new theoretical ansatz [V.N. Novikov, K.S. Schweizer, A.P. Sokolov, J. Chem. Phys. 138, 164508 (2013)], we have revisited the question of the characterization of the collective response of polyisobutylene at intermediate length scales observed by neutron spin echo (NSE) experiments. The model, generalized for sublinear diffusion –as it is the case of glass-forming polymers– has been successfully applied by using the information on the total self-motions available from MD-simulations properly validated by direct comparison with experimental results. From the fits of the coherent NSE data, the collective time at Q → 0 has been extracted that agrees very well with compiled results from different experimental techniques directly accessing such relaxation time. We show that a unique temperature dependence governs both, the Q → 0 and Q →∞ asymptotic characteristic times. The generalized model also gives account for the modulation of the apparent activation energy of the collective times with the static structure factor. It mainly results from changes of the short-range order at inter-molecular length scales.We thank support from the projects IT-654-13 (GV) and MAT2012-31088.Peer Reviewe

Democracy vs technocracy : national parliaments and fiscal agencies in EMU governance

Taken together, both technical and intergovernmental bodies have reinforced their positions in the EU macroeconomic governance framework. By contrast, representative assemblies have a much more limited role on a policy domain that has seen a significant overhaul of EU scrutiny, control and sanctioning powers. This means a reconfiguration of authority, delegation and the institutional governance of the Eurozone. In order to asses these changes, this study looks specifically at two recent developments in the EMU governance framework: the creation and consolidation of Independent Fiscal Institutions (IFIs) and the role of national parliaments in the European Semester. These two phenomena not only represent a significant innovation in terms of governance, but also a new example of the tension between technocracy and democracy that has been at the core of the EMU architecture since its inception and can be linked with the EU democratic deficit. The paper analyses the institutional design and the mandate of the IFIs, as well as the role played by the national parliaments in the European Semester. The analysis concludes that fiscal agencies can have mix effects over legitimacy, democratic representativeness, and accountability, arguing that the key to know which effect dominates over the other lies in the cooperation between fiscal agencies and national parliaments. This cooperation could also improve the national parliaments´ effectiveness and their ability to scrutinize the governments and the European Semester

Diseño de propuesta de mejora de la calidad de procesos y procedimientos técnicos y administrativos para la instalación de servicios triple play por medio de la red de fibra óptica de la empresa Claro

Diseñar una propuesta de mejora de la calidad de procesos y procedimientos técnicos y administrativos para la instalación de servicios triple play por medio de la red de fibra óptica de la empresa Claro, así realizar un diagnóstico de la situación actual y documentar los métodos y procedimientos operativos y administrativos necesarios para la realización de las instalaciones de servicios residenciales a través de la red de fibra óptica y elaborar los catálogos de materiales, herramientas y equipos necesarios para las instalaciones en la red de fibra óptica

Insight into the Structure and Dynamics of Polymers by Neutron Scattering Combined with Atomistic Molecular Dynamics Simulations

Combining neutron scattering and fully atomistic molecular dynamics simulations allows unraveling structural and dynamical features of polymer melts at different length scales, mainly in the intermolecular and monomeric range. Here we present the methodology developed by us and the results of its application during the last years in a variety of polymers. This methodology is based on two pillars: (i) both techniques cover approximately the same length and time scales and (ii) the classical van Hove formalism allows easily calculating the magnitudes measured by neutron scattering from the simulated atomic trajectories. By direct comparison with experimental results, the simulated cell is validated. Thereafter, the information of the simulations can be exploited, calculating magnitudes that are experimentally inaccessible or extending the parameters range beyond the experimental capabilities. We show how detailed microscopic insight on structural features and dynamical processes of various kinds has been gained in polymeric systems with different degrees of complexity, and how intriguing questions as the collective behavior at intermediate length scales have been faced.This research was funded by the Basque Government, code: IT-1175-19 and the Ministerio de Economía y Competitividad code: PGC2018-094548-B-I00 (MCIU/AEI/FEDER, UE)

The Debye’s model for the dielectric relaxation of liquid water and the role of cross-dipolar correlations. A MD-simulations study

By means of massive (more than 1.2 · 106 molecules) molecular dynamics simulations at 300 K we have disentangled self- and cross-dipolar contributions to the dielectric relaxation of liquid water that cannot be experimentally resolved. We have demonstrated that cross dipolar correlations are of paramount importance. They amount for almost a 60% of the total dielectric amplitude. The corresponding relaxation function is a one-step Debye-like function with a characteristic time, τcross, of the order of the phenomenological Debye time, τD. In contrast, the relaxation function corresponding to the self-contribution is rather complex and contains a fast decay related to dipolar librations and a second relaxation step that can be well described by two exponentials: a low-amplitude fast process (τ0 = 0.31 ps) and a main slow process (τself = 5.4 ps) that fully randomizes the dipolar orientation. In addition to dipolar relaxation functions, we have also calculated scattering-like magnitudes characterizing translation and rotation of water molecules. Although these processes can be considered as “jump” processes in the short time range, at the time scale of about τD–τcross, at which the cross-dipolar correlations decay to zero, the observed behavior cannot be distinguished from that corresponding to uncoupled Brownian translational and rotational diffusion. We propose that this is the reason why the Debye model, which does not consider intermolecular dipolar interactions, seems to work at time t ≳ τD.We acknowledge the Grant No. PID2021-123438NB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe,” Grant No. TED2021-130107A-I00 funded by MCIN/AEI/10.13039/501100011033 and Unión Europea “NextGenerationEU/PRTR,” as well as financial support of Eusko Jaurlaritza, code: IT1566-22 and from the IKUR Strategy under the collaboration agreement between Ikerbasque Foundation and the Materials Physics Center on behalf of the Department of Education of the Basque Government

Fannia fusconotata and Fannia sanihue (Diptera: Fanniidae): First records in Uruguay and distribution extension

Fannia fusconotata (Rondani, 1868) and Fannia sanihue Domínguez & Aballay, 2008 are recorded for the first time in Uruguay, extending the Neotropical distribution of these taxa eastward in South America. The specimens were collected using modified Malaise traps located above pig carcasses in Pando, Canelones, Uruguay, from February to April 2011. This contribution is a part of the first study to be undertaken into forensic entomology in Uruguay.Fil: Remedios De León, Mónica. Universidad de la República. Facultad de Ciencias; UruguayFil: Aballay, Fernando Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Dominguez, Martha Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: González Vainer, Patricia. Universidad de la República. Facultad de Ciencias; Urugua

The free-volume structure of a polymer melt, poly(vinyl methylether) from molecular dynamics simulations and cavity analysis

10 pages, 6 figures, 2 tables.In this work we analyze and compare the free volume of a polymer system poly(vinyl methylether) (PVME) at 300 K obtained by the two direct but different approaches: Positron annihilation lifetime spectroscopy (PALS) and computer simulations. The free volume is calculated from the simulated cells of PVME by means of numerical methods based on grid scanning and probing the structure with a probe of a given radius RP. The free-volume structure was found to be percolated for small probes at RP=0.53 Å. As the probe radius increases, the cavity structure breaks into isolated cavities, reaching a maximum of the cavity number at RP=0.78 Å. We further develop methods for a geometrical analysis of the free-volume cavities by considering their shape. The geometrical computations show that the cavities have elongated shape with side-to-length ratio corresponding to approximately 1:0.55 and with an average length of 6 Å. Based on the overlap between the computed cavities and simplified geometrical representations, the best match of the cavity shape is obtained for the approximation to the ellipsoidal shape (overlap on 84.4%). A match with other examined shapes follows the sequence: ellipsoid>cylinder>bar>sphere>cube. Finally, the computed geometrical parameters are used as input parameters into the quantum-mechanical models for the orthopositronium (o-Ps) lifetime in various free-volume hole geometries. Comparison with the experimental data gives support for two ideas about the existence of an o-Ps particle in the polymeric matrix: (i) the positronium cannot localize in a portion of very small cavities; (ii) and in the case of the percolated cavities, several o-Ps particles occupy some subcavities in the same cavity. Additionally, radial distribution functions of the free volume indicate the existence of two kinds of free volume, a structured one, corresponding to interstitial spaces along the polymer chain, and the so-called “bulk free volume,” distributed randomly in the structure. PALS measurements seem to be mainly related with this bulk free volume. The cavities represented by the idealized geometries are visualized in three-dimensional space providing a unique representation on the free-volume structures.This work was supported by the VEGA Agency, Slovakia under Grant No. 2/0014/09(J.B.)and Project No. MAT2007-63681 (Spanish Ministry of Education), Grant No. IT-436-07 (Basque Government) and Project No. 2007SK0008 between Slovak Academy of Sciences (SAS) and Spanish Research Council (CSIC) Support from the project Spanish MEC Grant No. CSD2006-53 is also acknowledged.Peer reviewe

On ℓ∞- Grothendieck subspaces

A closed subspace S of l - is said to be a l -Grothendieck subspace if co c S (hence l - c S**) and every [sigma] (S*, S)-convergent sequence in S* is [sigma](S*, l)-convergent. Here we give examples of closed subspaces of l- containing co which are or fail to be l -Grothendiec.The authors were supported by Ministerio de Ciencia, Innovación y Universidades (Spain), grants PGC2018-101514-B-I00, PID2019-103961GB-C22, and by Vicerrectorado de Investigación de la Universidad de Cádiz. This work was also co-financed by the 2014-2020 ERDF Operational Programme, and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia, project reference: FEDER-UCA18-108415