Multi-site H-bridge breathers in a DNA--shaped double strand

We investigate the formation process of nonlinear vibrational modes representing broad H-bridge multi--site breathers in a DNA--shaped double strand. Within a network model of the double helix we take individual motions of the bases within the base pair plane into account. The resulting H-bridge deformations may be asymmetric with respect to the helix axis. Furthermore the covalent bonds may be deformed distinctly in the two backbone strands. Unlike other authors that add different extra terms we limit the interaction to the hydrogen bonds within each base pair and the covalent bonds along each strand. In this way we intend to make apparent the effect of the characteristic helicoidal structure of DNA. We study the energy exchange processes related with the relaxation dynamics from a non-equilibrium conformation. It is demonstrated that the twist-opening relaxation dynamics of a radially distorted double helix attains an equilibrium regime characterized by a multi-site H-bridge breather.Comment: 27 pages and 10 figure

Multiple hypothesis testing and clustering with mixtures of non-central t-distributions applied in microarray data analysis

Multiple testing analysis, based on clustering methodologies, is usually applied in Microarray Data Analysis for comparisons between pair of groups. In this paper, we generalize this methodology to deal with multiple comparisons among more than two groups obtained from microarray expressions of genes. Assuming normal data, we define a statistic which depends on sample means and sample variances, distributed as a non-central t-distribution. As we consider multiple comparisons among groups, a mixture of non-central t-distributions is derived. The estimation of the components of mixtures is obtained via a Bayesian approach, and the model is applied in a multiple comparison problem from a microarray experiment obtained from gorilla, bonobo and human cultured fibroblasts.Clustering, MCMC computation, Microarray analysis, Mixture distributions, Multiple hypothesis testing, Non-central t-distribution

Prolamin content and grain weight in RNAi silenced wheat lines under different conditions of temperature and nitrogen availability

Temperature and nitrogen (N) availability are two important environmental factors that may produce important changes in grain composition during grain filling of bread wheat. In this study, four wheat lines with the down-regulation of gliadins by means of RNA interference (RNAi) have been characterized to determine the effect of thermal stress and N availability on grain weight and quality; with focus on gliadin and glutenin protein fractions. Grain weight was reduced with heat stress (HS) in all RNAi lines, whereas gliadin content was increased in the wild-types. With respect to gliadin content, RNAi lines responded to HS and N availability differently from their respective wild-types, except for ω-gliadin content, indicating a very clear stability of silencing under different environmental conditions. In a context of increased temperature and HS events, and in environments with different N availability, the RNAi lines with down-regulated gliadins seem well suited for the production of wheat grain with low gliadin content.The Spanish Ministry of Economy and Competitiveness (Project AGL2016-80566-P) and the European Regional Development Fund (FEDER) supported this research

Can we simulate the biomechanical effects of exoskeletons prior to workstation implementation? Application of the Forces ergonomic method

Increasingly, exoskeletons are becoming a valuable tool for prevention technicians to promote occupational health and reduce the risk of musculoskeletal disorders in industry. However, the effective implementation of industrial exoskeletons is a complex challenge. Deciding whether these devices are the optimal solution to the detected ergonomic risks at a specific workstation is not straightforward. This study presents the modelling of three commercial passive exoskeletons, one for lumbar and two for shoulder risk reduction, to be considered in the musculoskeletal risk assessment of industrial workstations. The presented modelling considers the forces and moments applied by exoskeletons to the body using the Forces ergonomic method, providing the musculoskeletal risk for each joint based on inertial motion capture data registered at each workstation. This approach is exemplified on simulated and actual production workstations. The results reveal that the modelling application allows an objective understanding of the biomechanical effects of exoskeletons. Modelling establishes a predictive tool to assess and make decisions regarding the suitability of the exoskeleton prior to implementation at a workstation