Fighting Social Isolation With Nostalgia: Nostalgia as a Resource for Feeling Connected and Appreciated and Instilling Optimism and Vitality During the COVID-19 Pandemic

In two experiments, we tested the influence of bringing to mind a memory of a special moment versus an ordinary moment on nostalgia and whether this elicited nostalgia was related directly to gratitude and the satisfaction of need for relatedness and indirectly to optimism and vitality. Participants from Mexico were first asked to state how the pandemic of COVID-19 has affected their lives. After, participants were randomly assigned to one of two conditions: Memory of special moment versus memory of ordinary recent moment (study 1) or memory of special moment versus or memory of ordinary moment from the same life period as the special moment (study 2). After, participants completed a battery of questionnaires assessing nostalgia, gratitude and optimism (study 1) or nostalgia, satisfaction of need for relatedness, and vitality (study 2). Results from study 1 showed a positive influence of bringing to mind a special moment on nostalgia. Nostalgia was positively related to gratitude, which was then related positively to optimism. Similarly, results from study 2 showed a positive influence of bringing to mind a special moment on nostalgia. Nostalgia was positively related to satisfaction of need for relatedness, which then had a positive relationship with vitality. In both studies, the indirect sequential effect of bringing to mind a special moment on optimism and vitality was significant.

Polymorphic Iterable Sequential Effect Systems

Effect systems are lightweight extensions to type systems that can verify a wide range of important properties with modest developer burden. But our general understanding of effect systems is limited primarily to systems where the order of effects is irrelevant. Understanding such systems in terms of a semilattice of effects grounds understanding of the essential issues and provides guidance when designing new effect systems. By contrast, sequential effect systems—where the order of effects is important—lack an established algebraic structure on effects. We present an abstract polymorphic effect system parameterized by an effect quantale—an algebraic structure with well-defined properties that can model the effects of a range of existing sequential effect systems. We define effect quantales, derive useful properties, and show how they cleanly model a variety of known sequential effect systems. We show that for most effect quantales, there is an induced notion of iterating a sequential effect; that for systems we consider the derived iteration agrees with the manually designed iteration operators in prior work; and that this induced notion of iteration is as precise as possible when defined. We also position effect quantales with respect to work on categorical semantics for sequential effect systems, clarifying the distinctions between these systems and our own in the course of giving a thorough survey of these frameworks. Our derived iteration construct should generalize to these semantic structures, addressing limitations of that work. Finally, we consider the relationship between sequential effects and Kleene Algebras, where the latter may be used as instances of the former.

The three types of normal sequential effect algebras

A sequential effect algebra (SEA) is an effect algebra equipped with a sequential product operation modeled after the Lüders product (a,b)↦aba on C∗-algebras. A SEA is called normal when it has all suprema of directed sets, and the sequential product interacts suitably with these suprema. The effects on a Hilbert space and the unit interval of a von Neumann or JBW algebra are examples of normal SEAs that are in addition convex, i.e. possess a suitable action of the real unit interval on the algebra. Complete Boolean algebras form normal SEAs too, which are convex only when 0=1.We show that any normal SEA E splits as a direct sum E=Eb⊕Ec⊕Eac of a complete Boolean algebra Eb, a convex normal SEA Ec, and a newly identified type of normal SEA Eac we dub purely almost-convex.Along the way we show, among other things, that a SEA which contains only idempotents must be a Boolean algebra; and we establish a spectral theorem using which we settle for the class of normal SEAs a problem of Gudder regarding the uniqueness of square roots. After establishing our main result, we propose a simple extra axiom for normal SEAs that excludes the seemingly pathological a-convex SEAs. We conclude the paper by a study of SEAs with an associative sequential product. We find that associativity forces normal SEAs satisfying our new axiom to be commutative, shedding light on the question of why the sequential product in quantum theory should be non-associative.

Age-Related Structural and Functional Changes of the Hippocampus and the Relationship with Inhibitory Control

Aging is associated with structural and functional changes in the hippocampus, and hippocampal dysfunction represents a risk marker of Alzheimer’s disease. Previously, we demonstrated age-related changes in reactive and proactive control in the stop signal task, each quantified by the stop signal reaction time (SSRT) and sequential effect computed as the correlation between the estimated stop signal probability and go trial reaction time. Age was positively correlated with the SSRT, but not with the sequential effect. Here, we explored hippocampal gray matter volume (GMV) and activation to response inhibition and to p(Stop) in healthy adults 18 to 72 years of age. The results showed age-related reduction of right anterior hippocampal activation during stop success vs. go trials, and the hippocampal activities correlated negatively with the SSRT. In contrast, the right posterior hippocampus showed higher age-related responses to p(Stop), but the activities did not correlate with the sequential effect. Further, we observed diminished GMVs of the anterior and posterior hippocampus. However, the GMVs were not related to behavioral performance or regional activities. Together, these findings suggest that hippocampal GMVs and regional activities represent distinct neural markers of cognitive aging, and distinguish the roles of the anterior and posterior hippocampus in age-related changes in cognitive control.

Rényi Entropy and Rényi Divergence in Sequential Effect Algebra

The aim of this study is to extend the results concerning the Shannon entropy and Kullback–Leibler divergence in sequential effect algebra to the case of Rényi entropy and Rényi divergence. For this purpose, the Rényi entropy of finite partitions in sequential effect algebra and its conditional version are proposed and the basic properties of these entropy measures are derived. In addition, the notion of Rényi divergence of a partition in sequential effect algebra is introduced and the basic properties of this quantity are studied. In particular, it is proved that the Kullback–Leibler divergence and Shannon’s entropy of partitions in a given sequential effect algebra can be obtained as limits of their Rényi divergence and Rényi entropy respectively. Finally, to illustrate the results, some numerical examples are presented.

The sequential effect of CSR and COE: family ownership moderation

Purpose This paper aims to examine the sequential effect of cost of equity capital and corporate social responsibility (CSR) disclosure with family ownership as a moderating variable. Design/methodology/approach This empirical study examines samples of manufacturing firm in Indonesia using multiple regression analysis. Findings Firms with high cost of equity capital in previous years have extensive CSR disclosure level. Further, firms with extensive CSR disclosure get benefit of lower cost of equity capital in the following year. Family ownership weakens the effect of previous years cost of equity capital on CSR disclosure. On the other hand, family ownership does not moderate the effect of CSR disclosure on the cost of equity capital. Research limitations/implications This study has limitations in terms of CSR measurement using keywords which may not include overall reporting contents. This study also excludes information in sustainability reports and websites, images and scanned files that may provide additional information about the company’s social and environmental activities. This study is limited in terms of the generalization aspect because it only examines firms in one type of industry in one country over three years’ period. Originality/value This study provides empirical evidence on the sequential effect of cost of equity capital and CSR disclosure with family ownership as moderating variable from an emerging market context, which has been rarely explored in the previous research.