Long-term heart rate variability as a predictor of patient age

Patients age has been estimated in healthy population by means of the heart rate variability (HRV) parameters to assess the potentiality of HRV indexes as a biomarker of age. A long-term analysis of HRV has been performed, computing linear time and frequency domain parameters as well as non-linear metrics, in a dataset of 113 healthy subjects (age range 20-85 years old). The principal component analysis has been used to capture age-related influence on HRV and then three different models have been applied to predict subjects age: a robust linear regressor (RLR), a feedforward neural network (FFNN) and a radial basis function neural network (RBFNN). A good prediction of patient age has been obtained (using all principal components, the Pearson correlation coefficient between predicted and real age: RLR=0.793; FFNN=0.872; RBFNN=0.829), even if an overestimation in younger subjects and an underestimation in older ones may be observed. The important and complementary contribution of non-linear indexes to aging related HRV modifications has also been underlined.     

Some remarks on the robust Schur stability analysis of interval polynomials

The Schur stability analysis of an interval polynomial family can be quickly performed through a unique, suitably defined extreme polynomial. The purpose of this article is to provide some improvements with respect to the actually existing methods based on this approach.     

Parallel algebraic multilevel Schwarz preconditioners for a class of elliptic PDE systems

Algebraic multilevel preconditioners for algebraic problems arising from the discretization of a class of systems of coupled elliptic partial differential equations (PDEs) are presented. These preconditioners are based on modifications of Schwarz methods and of the smoothed aggregation technique, where the coarsening strategy and the restriction and prolongation operators are defined using a point-based approach with a primary matrix corresponding to a single PDE. The preconditioners are implemented in a parallel computing framework and are tested on two representative PDE systems. The results of the numerical experiments show the effectiveness and the scalability of the proposed methods. A convergence theory for the twolevel case is presented.     

A mixed numerical–analytical stable pseudo‐inversion method aimed at attaining an almost exact tracking

This paper considers the problem of computing the input u(t) of an internally asymptotically stable, possibly non‐minimum phase, linear, continuous time system Σ yielding a very accurate tracking of a pre‐specified desired output trajectory . The main purpose of the new approach proposed here is to alleviate some limitations that inherent the classical methods developed in the framework of the preview‐based stable inversion, which represents an important reference context for this class of control problems. In particular, the new method allows one to deal with arbitrary and possibly uncertain initial conditions and does not require a pre‐actuation. The desired output to be exactly tracked in steady state is here assumed to belong to the set of polynomials, exponential, and sinusoidal time functions. The desired transient response is specified to obtain a fast and smooth transition toward the steady‐state trajectory , without under and/or overshoot in the case of a set point reset. The transient control input u_t(t) is a priori assumed to be given by a piecewise polynomial function. Once has been specified, this allows the computation of the unknown u_t(t) as the approximate least squares solution of the Fredholm's integral equation corresponding to the explicit formula of the output forced response. The steady‐state input u_s(t) is analytically computed exploiting the steady‐state output response expressions for inputs belonging to the same set of . Copyright © 2013 John Wiley & Sons, Ltd.     

Development of convection in binary mixture with soret effect

The future Space experiment IVIDIL is planned to study the influence of vibration stimuli on the measurements of diffusion and thermodiffusion coefficients. A binary mixture of water and isopropanol is chosen as a working liquid. The principle of the Space experiment and ground based research are outlined. In addition preparatory experiments might be performed during parabolic flights. Results of 3D numerical simulations of thermal vibrational convection in binary mixture at the conditions of the parabolic flight are presented. Heat and mass transport arising in the system with increasing of vibration actions is discussed.     

Oxidation Processes for Alloys in the Ni – Zr System. Part 2. Phase Composition of Scale Formed on Ni7Zr2

We have used x-ray and metallographic layer-by-layer phase analysis to study the structure and composition of scale formed on the alloy Ni₇Zr₂ during its oxidation in air over a period of 1 h and 10 h in the temperature range 500-1200°C. In the scale we find NiO, the cubic and monoclinic modifications of ZrO₂, and also Ni and Ni₅Zr. The phase components are nonuniformly distributed over the thickness of the scale. The outer scale consists of the oxides NiO and ZrO₂, while the composition of the inner scale includes Ni and Ni₅Zr in addition to monoclinic ZrO₂. Cubic ZrO₂ is formed on the surface of the specimen in the initial stages of its oxidation at 500-700°C. For T ≥ 900°C, on the surface of the scale we find both modifications of ZrO₂, while the nickel phase is itself a solid solution Ni(Zr). We note that the mechanisms for the formation of low-temperature (T ≤ 800°C) and high-temperature (T ≥ 900°C) scales are different. It is hypothesized that these differences are determined mainly by the fact that at high temperatures, diffusion of zirconium ions toward the outer boundary of the scale is superimposed on diffusion of oxygen toward the scale – alloy boundary.     

A DNA origami plasmonic sensor with environment-independent read-out

Nano Research - DNA origami is a promising technology for its reproducibility, flexibility, scalability and biocompatibility. Among the several potential applications, DNA origami has been proposed...     

Lifetime Enhancement of Sensor Networks by the Moth Flame Optimization

Wireless Personal Communications - Advancements in wireless communication technologies have facilitated the deployment of large-scale Wireless Sensor Networks (WSNs). Due to the constraint of...     

Microstructured Photopolymerization of Liquid Crystalline Elastomers in Oxygen‐Rich Environments

Liquid crystal elastomers (LCEs) are soft materials that undergo large anisotropic shape change in response to stimuli. Rational organization of the local director field can impart spatial control of the strain profile, enabling stretch‐based deformation capable of nearly 20 J kg^?1 of output force. LCEs are increasingly being considered in end‐use applications in robotics, therapeutics, and optics. Here, a new synthetic approach is introduced to prepare LCEs composed of main chain mesogens via the cationic photopolymerization of the epoxy liquid crystal monomer (LCM). This examination details the optical, mechanical, and thermal properties of epoxide‐based LCEs as a function of spacer length (3, 6, or 11 carbons). The oxygen insensitivity of the cationic photopolymerization of these monomers makes this approach particularly attractive for implementation with emerging additive manufacturing techniques. This contribution focuses on microstructuring LCEs via 2‐photon direct laser writing (2P‐DLW). A custom heated cell facilitated 2P‐DLW of the aligned LCE epoxy resin melts to fabricate diverse geometric arrays. Enabled by the orthogonality of the reaction chemistry, hybrid and microstructured material compositions are prepared via the encapsulation of LCE epoxy micropatterns with free‐radical polymerization of acrylate‐based LCEs. The distinct thermomechanical response of the hybridized and microstructured LCE composites enables local and spatially controlled actuation.