Stability Conditions of a Class of Linear Retarded Differential Systems

In this paper, we give some new necessary and sufficient conditions for the asymptotic stability of a linear retarded differential system with two delays x′(t)+(1-a)x(t)+A(x(t-k)+x(t-l))=0, t≥0,where a<1 is a real number, A is a 2×2 real constant matrix, and k, l are positive numbers such that k>l

On the Asymptotic Stability of the Nonlinear Difference Equation System

In this paper, we obtain some new results on the equi-boundedness of solutions and asymptotic stability for a class of nonlinear difference systems with variable delay of the form x(n+1)=ax(n)+B(n)F(x(n−m(n))), n=0,1,2,...x(n+1)=ax(n)+B(n)F(x(n−m(n))),\ \ \ \ \ \ n=0,1,2,... where FF is the real valued vector function, m:Z→Z+,m:Z→Z+, which is bounded function and maximum value of mm is kk and is a k×kk×k variable coefficient matrix. We carry out the proof of our results by using the Banach fixed point theorem and we use these results to determine the asymptotic stability conditions of an example

A Self-Reference False Memory Effect in the DRM Paradigm: Evidence from Eastern and Western Samples

It is well established that processing information in relation to oneself (i.e., selfreferencing) leads to better memory for that information than processing that same information in relation to others (i.e., other-referencing). However, it is unknown whether self-referencing also leads to more false memories than other-referencing. In the current two experiments with European and East Asian samples, we presented participants the Deese-Roediger/McDermott (DRM) lists together with their own name or other people’s name (i.e., “Trump” in Experiment 1 and “Li Ming” in Experiment 2). We found consistent results across the two experiments; that is, in the self-reference condition, participants had higher true and false memory rates compared to those in the other-reference condition. Moreover, we found that selfreferencing did not exhibit superior mnemonic advantage in terms of net accuracy compared to other-referencing and neutral conditions. These findings are discussed in terms of theoretical frameworks such as spreading activation theories and the fuzzytrace theory. We propose that our results reflect the adaptive nature of memory in the sense that cognitive processes that increase mnemonic efficiency may also increase susceptibility to associative false memories

Differential effects of valence and encoding strategy on internal source memory and judgments of source: exploring the production and the self-reference effect

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fpsyg.2019.01326/full#supplementary-materialItem memory studies show that emotional stimuli are associated with improved memory performance compared to neutral ones. However, emotion-related effects on source memory are less consistent. The current study probed how emotional valence and specific encoding conditions influence internal source memory performance and judgments of source (JOSs). In two independent experiments, participants were required to read silently/aloud (Experiment 1) or to perform self-reference/common judgments (Experiment 2) on a list of negative/neutral/positive words. They also performed immediate JOSs ratings for each word. The study phase was followed by a test phase in which participants performed old-new judgments. In Experiment 1, the production effect was replicated for item memory, but the effects of valence on item and source memory were not significant. In Experiment 2, self-referential processing effects on item and source memory differed as a function of valence. In both experiments, JOSs ratings were sensitive to valence and encoding conditions, although they were not predictive of objective memory performance. These findings demonstrate that the effects of valence on internal source memory and JOSs are modulated by encoding strategy. Thus, the way information is encoded can shed light on how emotion might enhance, impair or exert no influence on source memory.This work was supported by a Ph.D. Fellowship (PD/BD/105964/2014), awarded to DP, funded by the Portuguese Science Foundation (FCT) through national funds and cofunded by the European Social Fund (ESF) through the Operational Programme for Human Capital (POCH). It was also supported by a research grant (PTDC/MHC-PCN/0101/2014) funded by FCT and awarded to AP. The study was conducted at the Psychology Research Centre (PSI/01662), School of Psychology, University of Minho, and supported by FCT and the Portuguese Ministry of Science, Technology and Higher Education (UID/PSI/01662/2019), through the national funds (PIDDAC) and co-funded by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653)

The self-reference effect in dementia: Differential involvement of cortical midline structures in Alzheimer’s disease and behavioural-variant frontotemporal dementia

Encoding information in reference to the self enhances subsequent memory for the source of this information. In healthy adults, self-referential processing has been proposed to be mediated by the cortical midline structures (CMS), with functional differentiation between anterior-ventral, anterior-dorsal and posterior regions. While both Alzheimer’s disease (AD) and behavioural-variant frontotemporal dementia (bvFTD) patients show source memory impairment, it remains unclear whether they show a typical memory advantage for self-referenced materials. We also sought to identify the neural correlates of this so-called ‘self-reference effect’ (SRE) in these patient groups. The SRE paradigm was tested in AD (n=16) and bvFTD (n=22) patients and age-matched healthy controls (n=17). In this task, participants studied pictures of common objects paired with one of two background scenes (sources) under self-reference or other-reference encoding instructions, followed by an item and source recognition memory test. Voxel-based morphometry was used to investigate correlations between SRE measures and regions of grey matter atrophy in the CMS. The behavioural results indicated that self-referential encoding did not ameliorate the significant source memory impairments in AD and bvFTD patients. Furthermore, the reduced benefit of self-referential relative to other-referential encoding was not related to general episodic memory deficits. Our imaging findings revealed that reductions in the SRE were associated with atrophy in the anterior-dorsal CMS across both patient groups, with additional involvement of the posterior CMS in AD and anterior-ventral CMS in bvFTD. These findings suggest that although the SRE is comparably reduced in AD and bvFTD, this arises due to impairments in different subcomponents of self-referential processing

Stability conditions a class of linear delay difference systems

In this paper, we give new necessary and sufficient conditions for the asymptotic stability of a linear delay difference system: $x_{n+1}-ax_{n}-Ax_{n-k}=0$, where A is a $2\times 2$ constant matrix, k is a nonnegative integer and a is a real number. To prove the theorems, root analysis is used for characteristic equation of system

On asymptotic stability of a class of time–delay systems

In this paper, we give some new necessary and sufficient conditions for the asymptotic stability of a class of time–delay systems of the form $$x'\left(t \right) + \left({1 - a} \right)x\left(t \right) + A\left({x\left({t - k} \right) + x\left({t - l} \right)} \right) = 0,\,t \ge 0,$$ where $$a$$ is a real number, $$A$$ is a $$2 \times 2$$ real constant matrix, and $$k$$, $$l$$ are positive numbers such that $$k \ \gt\ l$$