A refined hydrogen bond potential for flexible protein models

One of the major disadvantages of coarse-grained hydrogen bond potentials, for their use in protein folding simulations, is the appearance of abnormal structures when these potentials are used in flexible chain models, and no other geometrical restrictions or energetic contributions are defined into the system.We have efficiently overcome this problem, for chains of adequate size in a relevant temperature range, with a refined coarse-grained hydrogen bond potential. With it, we have been able to obtain nativelike alpha-helices and beta-sheets in peptidic systems, and successfully reproduced the competition between the populations of these secondary structure elements by the effect of temperature and concentration changes. In this manuscript we detail the design of the interaction potential and thoroughly examine its applicability in energetic and structural terms, considering factors such as chain length, concentration, and temperature

Implementación de proceso de capacitación y mejora de registros en un laboratorio de análisis

El objetivo de esta intervención es optimizar los registros utilizados en un laboratorio de análisis mediante la revisión y estandarización de los mismos en los diferentes análisis realizados por la empresa. En esta intervención fue necesario utilizar diferentes herramientas de calidad para ayudar en la correcta definición del problema, la medición, el análisis, la implementación, y el seguimiento de las mejoras. La intervención se ejecutó con base en la metodología DMAIC, de tal forma que al final fue posible optimizar y reducir paulatinamente el costo operativo del laboratorio de análisis. La definición del problema se realizó mediante la revisión de la información relacionada con los problemas de personal que atravesaba la empresa. Para el proceso de medición, se utilizó tanto la revisión de datos históricos sobre el funcionamiento de los procesos como la recogida de datos en el día a día de la empresa. El análisis de la información se revisó con el uso de diferentes herramientas de calidad que ayudarán a tomar una decisión fundamentada. La implementación del proceso de mejora y control se basó en la estandarización de los procesos mediante la implementación de indicadores clave en los procesos que ayuden a ahorrar recursos de la empresa. Se utilizaron diferentes herramientas durante el proyecto como FODA, FMEA, diagrama de Pareto, QFD, hojas de verificación, histograma, SIPOC, diagrama de Pareto, diagrama de dispersión, histograma, diagrama de causa-efecto, diagramas de control y diagramas de flujo.ITESO, A. C

Microscopic dynamics of glycerol in its crystalline and glassy states

The dynamics of crystalline glycerol are studied by means of Raman spectroscopy and lattice dynamics calculations employing a semiflexible model to represent the low-lying molecular vibrations. The latter is validated against structural, thermodynamic, and spectroscopic data. The results serve to set an absolute frequency scale for glassy glycerol, which is also studied by Raman and incoherent inelastic-neutron scattering. Some implications of the present findings regarding ensuing discussions on glassy dynamics are finally commented on.Dirección General de Investigaciones Científicas y Técnicas PB92- 0114-C0

Thermal transport in glassy selenium: The role of low-frequency librations

The experimental curves giving the temperature dependence of the thermal conductivity of glassy selenium are considered in detail. The observed behavior can be taken into account quantitatively if the densities of states for short-wavelength phonons as well as for low-energy librations arising from computer simulations are used for the calculations. In particular, it is shown that the lowest frequency excitations of a chain of selenium atoms can give due account of the plateau observed at temperatures about 2-10 K. The implications of the present findings for the current debate regarding the mechanisms for thermal transport in glasses are finally discussedDirección General de Investigación Científica y Técnica PB92-0114-C0

Tunable uptake of poly(ethylene oxide) by graphite-oxide-based materials

We investigate the role of structure and chemical composition on the uptake of poly(ethylene oxide) by a series of graphite oxides (GOs) and thermally reduced GOs, leading to the formation of polymer-intercalated GO and polymer-adsorbed graphene nanostructures. To this end, a series of poly(ethylene oxide) (PEO) - GO hybrid materials exhibiting a variable degree of GO oxidation and exfoliation has been investigated in detail using a combination of techniques including X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetry, scanning-electron microscopy, and nitrogen adsorption. Intercalation of the polymer phase into well-defined GO galleries is found to correlate well with both the degree of GO oxidation and with the presence of hydroxyl groups. The latter feature is an essential prerequisite to optimize polymer uptake owing to the predominance of hydrogen-bonding interactions between intercalant and host. Unlike the bulk polymer, these intercalation compounds show neither crystallisation nor glass-transition associated with the polymer phase. Exfoliation and reduction of GO result in high-surface-area graphene layers exhibiting the highest polymer uptake in these GO-based materials. In this case, PEO undergoes surface adsorption, where we observe the recovery of glass and melting transitions associated with the polymer phase albeit at significantly lower temperatures than the bulk

A remark on an overdetermined problem in Riemannian Geometry

Let $(M,g)$ be a Riemannian manifold with a distinguished point $O$ and assume that the geodesic distance $d$ from $O$ is an isoparametric function. Let $\Omega\subset M$ be a bounded domain, with $O \in \Omega$, and consider the problem $\Delta_p u = -1$ in $\Omega$ with $u=0$ on $\partial \Omega$, where $\Delta_p$ is the $p$-Laplacian of $g$. We prove that if the normal derivative $\partial_{\nu}u$ of $u$ along the boundary of $\Omega$ is a function of $d$ satisfying suitable conditions, then $\Omega$ must be a geodesic ball. In particular, our result applies to open balls of $\mathbb{R}^n$ equipped with a rotationally symmetric metric of the form $g=dt^2+\rho^2(t)\,g_S$, where $g_S$ is the standard metric of the sphere.Comment: 8 pages. This paper has been written for possible publication in a special volume dedicated to the conference "Geometric Properties for Parabolic and Elliptic PDE's. 4th Italian-Japanese Workshop", organized in Palinuro in May 201

Transposable element polymorphisms improve prediction of complex agronomic traits in rice

Acord transformatiu CRUE-CSICKey message: Transposon insertion polymorphisms can improve prediction of complex agronomic traits in rice compared to using SNPs only, especially when accessions to be predicted are less related to the training set. Abstract: Transposon insertion polymorphisms (TIPs) are significant sources of genetic variation. Previous work has shown that TIPs can improve detection of causative loci on agronomic traits in rice. Here, we quantify the fraction of variance explained by single nucleotide polymorphisms (SNPs) compared to TIPs, and we explore whether TIPs can improve prediction of traits when compared to using only SNPs. We used eleven traits of agronomic relevance from by five different rice population groups (Aus, Indica, Aromatic, Japonica, and Admixed), 738 accessions in total. We assess prediction by applying data split validation in two scenarios. In the within-population scenario, we predicted performance of improved Indica varieties using the rest of Indica accessions. In the across population scenario, we predicted all Aromatic and Admixed accessions using the rest of populations. In each scenario, Bayes C and a Bayesian reproducible kernel Hilbert space regression were compared. We find that TIPs can explain an important fraction of total genetic variance and that they also improve genomic prediction. In the across population prediction scenario, TIPs outperformed SNPs in nine out of the eleven traits analyzed. In some traits like leaf senescence or grain width, using TIPs increased predictive correlation by 30-50%. Our results evidence, for the first time, that TIPs genotyping can improve prediction on complex agronomic traits in rice, especially when accessions to be predicted are less related to training accessions