Steady-state analysis of networked epidemic models

Compartmental epidemic models with dynamics that evolve over a graph network have gained considerable importance in recent years but analysis of these models is in general difficult due to their complexity. In this paper, we develop two positive feedback frameworks that are applicable to the study of steady-state values in a wide range of compartmental epidemic models, including both group and networked processes. In the case of a group (resp. networked) model, we show that the convergence limit of the susceptible proportion of the population (resp. the susceptible proportion in at least one of the subgroups) is upper bounded by the reciprocal of the basic reproduction number (BRN) of the model. The BRN, when it is greater than unity, thus demonstrates the level of penetration into a subpopulation by the disease. Both non-strict and strict bounds on the convergence limits are derived and shown to correspond to substantially distinct scenarios in the epidemic processes, one in the presence of the endemic state and another without. Formulae for calculating the limits are provided in the latter case. We apply the developed framework to examining various group and networked epidemic models commonly seen in the literature to verify the validity of our conclusions

On the exponential convergence of input-output signals of nonlinear feedback systems

We show that the integral-constraint-based robust feedback stability theorem for certain Lurye systems exhibits the property that the endogenous input-output signals enjoy an exponential convergence rate for all initial conditions of the linear time-invariant subsystem. More generally, we provide conditions under which a feedback interconnection of possibly open-loop unbounded subsystems to admit such an exponential convergence property, using perturbation analysis and a combination of tools including integral quadratic constraints, directed gap measure, and exponential weightings. As an application, we apply the result to first-order convex optimisation methods. In particular, by making use of the Zames-Falb multipliers, we state conditions for these methods to converge exponentially when applied to strongly convex functions with Lipschitz gradients.Comment: This paper has been submitted to Automatic

On the necessity and sufficiency of the Zames–Falb multipliers for bounded operators

This paper analyzes the robust feedback stability of a single-input-single-output stable linear time-invariant (LTI) system against three different classes of nonlinear systems using the Zames–Falb multipliers. The contribution is threefold. Firstly, we identify a class of uncertain systems over which the robust feedback stability is equivalent to the existence of an appropriate Zames–Falb multiplier. Secondly, when restricted to be static (a.k.a. memoryless), such a class of systems coincides with the class of sloped-restricted monotone nonlinearities, and the classical result of using the Zames–Falb multipliers to ensure feedback stability is recovered. Thirdly, when restricted to be LTI, the first class is demonstrated to be a subset of the second, and the existence of a Zames–Falb multiplier is shown to be sufficient but not necessary for the robust feedback stability.</div

Toxicological effects of As (V) in juvenile rockfish Sebastes schlegelii by a combined metabolomic and proteomic approach

Arsenic (As) is a metalloid element that is ubiquitous in the marine environment and its contamination has received worldwide attention due to its potential toxicity. Arsenic can induce multiple adverse effects, such as lipid metabolism disorder, immune system dysfunction, oxidative stress and carcinogenesis, in animals. Inorganic arsenic includes two chemical forms, arsenite (As (III)) and arsenate (As (V)), in natural environment. As (V) is the dominant form in natural waters. In the present study, metabolomic and proteomic alterations were investigated in juvenile rockfish Sebastes schlegelii exposed to environmentally relevant concentrations of As (V) for 14 d. The analysis of iTRAQ-based proteomics combined with untargeted NMR-based metabolomics indicated apparent toxicological effects induced by As (V) in juvenile rockfish. In details, the metabolites, including lactate, alanine, ATP, inosine and phosphocholine were significantly altered in As-treated groups. Proteomic responses suggested that As (V) could not only affected energy and primary metabolisms and signal transduction, but also influenced cytoskeleton structure in juvenile rockfish. This work suggested that the combined proteomic and metabolomic approach could shed light on the toxicological effects of pollutants in rockfish S. schlegelii. (C) 2019 Elsevier Ltd. All rights reserved

Effect of Iron Ion on Corrosion Behavior of Inconel 625 in High-Temperature Water

The corrosion behavior of an ultralow iron nickel-based alloy Inconel 625 under high-temperature water has been evaluated. The results show that surface oxidation and pitting were the principal corrosion mechanisms of Inconel 625 during the initial immersion period. The surface layer of the oxide film is first Ni-enriched and then Fe-enriched as immersion time increases. The iron ions dissolved from the autoclave could lead to the formation of NiFe2O4 and have a great influence on the oxidation behavior of Inconel 625. The oxides nucleated by solid-state reactions with selective dissolution of Fe and Ni and then grew up through precipitation of cations from solution

NIR-active Nanoterminator with Mature Dendritic Cell Acitivities for Immuno-Priming Mild Photothermal Cancer Therapy

Recently, photothermal-immuno synergistic therapy under mild temperature (~ 45 °C) has got broad interest in cancer treatment. Inhibition the intratumorally HSPs production is the key to accomplish highly efficient and mild photothermal therapy. In this work, we developed biomimetic nanoterminators with mature DCs functions by coating the mature dendritic cell membrane on photothermal nanoagents. As-prepared nanoterminators could automatically locate on T cell in the complex tumor-immune microenvironment and promote the T cells proliferation, activation and cytokine secretion, which could not only inhibit the expression of heat shock proteins to cooperate on highly efficient mild photothermal therapy (~42°C), but also promote tumor apoptosis during the treatment. More importantly, this nanoterminator could serve as vaccine to trigger anti-tumor immune response of the whole body, which would be promising to long-life tumor inhibition and termination