scholarly journals No need to choose: independent regulation of cognitive stability and flexibility challenges the stability-flexibility tradeoff

2021 ◽  
Author(s):  
Raphael Markus Geddert ◽  
Tobias Egner
Keyword(s):  
Cognitive Processes ◽  
Switch Costs ◽  
Cognitive Stability ◽  
Attentional Set Shifting ◽  
Current Task ◽  
Empirical Tests ◽  
The Stability ◽  
Contextual Adaptation ◽  
Robust Evidence ◽  
A Current

Adaptive behavior requires the ability to focus on a current task and protect it from distraction (cognitive stability) as well as the ability to rapidly switch to another task in light of changing circumstances (cognitive flexibility). Cognitive stability and flexibility have commonly been conceptualized as opposite endpoints on a stability-flexibility tradeoff continuum, implying an obligatory reciprocity between the two: greater flexibility necessitates less stability, and vice versa. Surprisingly, rigorous empirical tests of this critical assumption are lacking, however. Here, we tested this assumption by acquiring simultaneous measurements of cognitive stability (congruency effects) and flexibility (switch costs) while independently varying contextual demands on these functions with block-wise manipulations of the proportion of incongruent trials and task switches, respectively. If cognitive stability and flexibility are reciprocal, an increase in flexibility in response to higher switch rates should lead to a commensurate decrease in stability, and an increase in stability in response to more frequent incongruent trials should result in decreased flexibility. Across three experiments, using classic cued task switching (Experiments 1 and 3) and attentional set shifting (Experiment 2) protocols, we found robust evidence against an obligatory stability-flexibility tradeoff. Although we observed the expected contextual adaptation of stability and flexibility to changing demands, strategic adjustments in stability had no influence on flexibility, and vice versa. These results refute the long-held assumption of a stability-flexibility tradeoff, documenting instead that the cognitive processes mediating these functions can be regulated independently - it is possible to be both stable and flexible at the same time.

scholarly journals Contextual Adaptation of Cognitive Flexibility is driven by Task- and Item-Level Learning

2019 ◽  
Author(s):  
Audrey Siqi-Liu ◽  
Tobias Egner
Keyword(s):  
Cognitive Flexibility ◽  
Stimulus Item ◽  
Transfer Task ◽  
Learning Mechanisms ◽  
Behavioral Experiments ◽  
Task Set ◽  
Switch Costs ◽  
Cognitive Stability ◽  
Current Task ◽  
Task Sets

Adaptive behavior requires finding, and adjusting, an optimal tradeoff between focusing on a current task-set (cognitive stability) and updating that task-set when the environment changes (cognitive flexibility). Such dynamic adjustments of cognitive flexibility are observed in cued task-switching paradigms, where switch costs tend to decrease as the proportion of switch trials over blocks increases. However, the learning mechanisms underlying this phenomenon, here referred to as the list-wide proportion switch effect (LWPSE), are currently unknown.We addressed this question across four behavioral experiments. Experiment 1 replicated the basic LWPSE reported in previous studies. Having participants switch between three instead of two tasks, Experiment 2 demonstrated that the LWPSE is preserved even when the specific alternate task to switch to cannot be anticipated. Experiments 3a and 3b tested for the generalization of list-wide switch-readiness to an unbiased “transfer task,” presented equally often as switch and repeat trials, by intermixing the transfertask with biased tasks. Despite the list-wide bias, the LWPSE was only found for biased tasks, suggesting that the modulations of switch costs are task set and/or task stimulus (item)-specific. To evaluate these two possibilities, Experiment 4 employed biased versus unbiased stimuli within biased task sets and found switch-cost modulations for both stimuli sets. These results establish how people adapt their stability-flexibility tradeoff to different contexts. Specifically, our findings show that people learn to associate context appropriate levels of switch readiness with switch-predictive cues, provided by task sets as well as specific task stimuli.

Capital Market Consequences of Audit Office Size: Evidence from Stock Price Crash Risk

2020 ◽  
Vol 39 (2) ◽  
pp. 1-26
Author(s):  
Jeffrey L. Callen ◽  
Xiaohua Fang ◽  
Baohua Xin ◽  
Wenjun Zhang
Keyword(s):  
Capital Market ◽  
Stock Price ◽  
Bad News ◽  
Crash Risk ◽  
Public Firms ◽  
Big 4 ◽  
Empirical Tests ◽  
Office Size ◽  
Market Consequences ◽  
Robust Evidence

SUMMARY This study examines the association between the office size of engagement auditors and their clients' future stock price crash risk, a consequence of managerial bad news hoarding. Using a sample of U.S. public firms with Big 4 auditors, we find robust evidence that local audit office size is significantly and negatively related to future stock price crash risk. The evidence is consistent with the view that large audit offices effectively detect and deter bad news hoarding activities in comparison with their smaller counterparts. We further explore two possible explanations for these findings, the Auditor Incentive Channel and the Auditor Competency Channel. Our empirical tests offer support for both channels. JEL Classifications: G12; G34; M49.

scholarly journals Sliding Contacts in Planetary Magnetospheres

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 283
Author(s):  
Elena Belenkaya ◽  
Igor Alexeev
Keyword(s):  
Large Scale ◽  
Strong Field ◽  
Magnetized Plasma ◽  
Sliding Contacts ◽  
Radio Emissions ◽  
Planetary Magnetospheres ◽  
Current Task ◽  
Surrounding Space ◽  
Non Local ◽  
A Current

In the planetary magnetospheres there are specific places connected with velocity breakdown, reconnection, and dynamo processes. Here we pay attention to sliding layers. Sliding layers are formed in the ionosphere, on separatrix surfaces, at the magnetopauses and boundaries of stellar astrospheres, and at the Alfvén radius in the equatorial magnetosphere of rapidly rotating strongly magnetized giant planets. Although sliding contacts usually occur in thin local layers, their influence on the global structure of the surrounding space is very great. Therefore, they are associated with non-local processes that play a key role on a large scale. There can be an exchange between different forms of energy, a generation of strong field-aligned currents and emissions, and an amplification of magnetic fields. Depending on the conditions in the magnetosphere of the planet/exoplanet and in the flow of magnetized plasma passing it, different numbers of sliding layers with different configurations appear. Some are associated with regions of auroras and possible radio emissions. The search for planetary radio emissions is a current task in the detection of exoplanets.

scholarly journals Review of claudin proteins as potential biomarkers for necrotizing enterocolitis

2021 ◽  
Author(s):  
Victoria Griffiths ◽  
Niazy Al Assaf ◽  
Rizwan Khan
Keyword(s):  
Necrotizing Enterocolitis ◽  
Intestinal Permeability ◽  
Central Feature ◽  
Search Terms ◽  
Area Of Interest ◽  
Noninvasive Biomarker ◽  
Current Area ◽  
The Stability ◽  
Human Neonates ◽  
A Current

Abstract Background Claudin proteins are a component of tight junctions found in cell-cell adhesion complexes. A central feature of necrotizing enterocolitis (NEC) is intestinal permeability, with changes to claudin proteins potentially contributing to intestinal instability, inflammation, and the progression of NEC. A current area of interest is the development of a novel, noninvasive biomarker for the detection of NEC in neonates at risk of developing this disease, in order to reduce morbidity and mortality through earlier intervention. Aims This review aims to explore the relevance of claudin proteins in the pathophysiology of NEC and their potential usefulness as a biomarker. Methods This review was conducted using the search terms “claudin” + “necrotizing enterocolitis”, with 27 papers selected for review. Results Claudin proteins appear to have a role in the stability of the gut epithelium through the regulation of intestinal permeability, maturity, and inflammation. Formula feeding has been shown to promote inflammation and result in changes to claudin proteins, while breastfeeding and certain nutritional supplements lead to reduced inflammation and improved intestinal stability as demonstrated through changes to claudin protein expression. Preliminary studies in human neonates suggest that urinary claudin measurements may be used to predict the development of NEC. Conclusions Alterations to claudin proteins may reflect changes seen to intestinal permeability and inflammation in the context of NEC. Further research is necessary to understand the relevance of claudin proteins in the pathophysiology of NEC and their use as a biomarker.

scholarly journals Dynamics and stability of skyrmions in a bended nano-beam

2021 ◽  
Author(s):  
Anruo Zhong ◽  
Xiaoming Lan ◽  
Yangfan Hu ◽  
Biao Wang
Keyword(s):  
Energy Cost ◽  
High Mobility ◽  
Bending Moment ◽  
Elastic Fields ◽  
Spintronic Devices ◽  
Bulk Stress ◽  
The Stability ◽  
Magnetic Skyrmions ◽  
Nontrivial Topology ◽  
A Current

Abstract Magnetic skyrmions are attracting much attention due to their nontrivial topology and high mobility to electric current. Nevertheless, suppression of the skyrmion Hall effect and maintaining high velocity of skyrmions with low energy cost are two major challenges concerning skyrmion-based spintronic devices. Here we show theoretically that in a nano-beam suffering appropriate bending moment, both Bloch-type and Néel-type skyrmions move with a vanishing Hall angle under a current density smaller than that required when the bending is absent. Moreover, bending alone can be used to move skyrmions, whose velocity is solved analytically from the Thiele equation. Generally speaking, inhomogeneous elastic fields affect the stability and dynamics of skyrmions, where the local stability is dominantly determined by the local bulk stress. These findings throw new light on how to drive skyrmions straightly with lower energy cost, which is vital for utilizing skyrmions as information carriers.

Study of Dynamic Modes of Current Stabilization Systems of Powerful Electromagnets with Pulse-Width Modulation

2021 ◽  
Vol 22 (6) ◽  
pp. 313-320
Author(s):  
M. S. Lur’e ◽  
O. M. Lur’e ◽  
A. S. Frolov
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Functional Differential Equations ◽  
Original System ◽  
Nyquist Stability ◽  
Detailed Assessment ◽  
Functional Differential ◽  
The Stability ◽  
Automatic Systems ◽  
A Current

This study is devoted to the consideration of a method for assessing the stability of systems with pulse-width modulation, based on the linearization of its equivalent system with pulse-width modulation. An approximate study of the dynamic modes of operation of systems with pulse-width modulation, taking into account the stability for the system of automatic control of the supply current of electromagnets under the conditions of external and internal interference, is carried out. Variants of execution of schemes of pulse-width regulators for the power supply of an electromagnet based on a unipolar and bipolar element with pulse-width modulation are presented. The possibility of linearization of systems with pulse-width modulation for the subsequent detailed assessment of the stability of such systems is shown. The prospects of using functional differential equations for stability analysis of automatic systems with pulse-width modulation are shown. The frequency characteristics of an equivalent pulse system are analyzed using the example of a current stabilization system of high-power electromagnets with a pulse-width regulator, taking into account the replacement of the latitude modulation by the amplitude one. Based on the analysis of the resulting transfer function, which is a stable linearized equivalent open system, the ways of evaluating the stability of the original system with pulse-width modulation using the Nyquist stability criterion are proposed. The conclusion is made about the advantage of a system with PWM, in relation to a system with AIM, in terms of stability, and recommendations are given for the use of the obtained data in the analysis oftransients in such systems.

No paradox here? Improving theory and testing of the nuclear stability–instability paradox with synthetic counterfactuals

2021 ◽  
pp. 002234332110185
Author(s):  
Francesco Bailo ◽  
Benjamin E Goldsmith
Keyword(s):  
Synthetic Control ◽  
Nuclear War ◽  
Quantitative Studies ◽  
Limited Support ◽  
Before And After ◽  
Nuclear Stability ◽  
The Usa ◽  
Valid Comparison ◽  
Empirical Tests ◽  
The Stability

This article contributes to both the theoretical elaboration and empirical testing of the ‘stability–instability paradox’, the proposition that while nuclear weapons deter nuclear war, they also increase conventional conflict among nuclear-armed states. Some recent research has found support for the paradox, but quantitative studies tend to pool all international dyads while qualitative and theoretical studies focus almost exclusively on the USA–USSR and India–Pakistan dyads. This article argues that existing empirical tests lack clearly relevant counterfactual cases, and are vulnerable to a number of inferential problems, including selection on the dependent variable, unintentionally biased inference, and extrapolation from irrelevant cases. The limited evidentiary base coincides with a lack of consideration of the theoretical conditions under which the paradox might apply. To address these issues this article theorizes some scope conditions for the paradox. It then applies synthetic control, a quantitative method for valid comparison when appropriate counterfactual cases are lacking, to model international conflict between India–Pakistan, China–India, and North Korea–USA, before and after nuclearization. The article finds only limited support for the paradox when considered as a general theory, or within the theorized scope conditions based on the balance of resolve and power within each dyad.

Dehydration and Sieving to 150 Microns Process of Melon Seed

2019 ◽  
Vol 394 ◽  
pp. 39-46
Author(s):  
Imelda de Jesús Loera-Hernández ◽  
Gerardo Espinosa-Garza
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
Neuronal Function ◽  
Hormone Production ◽  
Great Demand ◽  
Pulp Industry ◽  
Current Task ◽  
Horticultural Products ◽  
Melon Seeds ◽  
A Current

Melon is one of the main horticultural products that are harvested in Mexico and is a sourceof employment and an important income for farmers in the country. Melon is in great demand in thejuice and pulp industry and nowadays it is a current task to develop technologies for the use ofprocessed seeds from melons. The objective of the present investigation is to determine the yield of15 minerals and the composition of fatty acids present in melon seeds in order to add value to thisresidue. Some polyphenols were also determined in order to verify their possible intake to reducecertain health problems. Allergies and lactose intolerances have increased in recent years andtherefore there has been a growing demand for alternatives. By taking advantage of the melon seeds,we sought to create a drink made of melon seeds as a substitute for milk. After performing severalexperiments in the lab, it was demonstrated that melon seeds contain high amounts of linoleic acid, asubstance that regulates hormone production, improves neuronal function, strengthens the immunesystem and reduces cholesterol, thus preventing certain cardiac problems.

scholarly journals To stay or not to stay: The stability of choice perseveration in value-based decision making

2020 ◽  
Vol 74 (1) ◽  
pp. 199-217
Author(s):  
Ulrike Senftleben ◽  
Martin Schoemann ◽  
Matthias Rudolf ◽  
Stefan Scherbaum
Keyword(s):  
Decision Making ◽  
Stimulus Onset Asynchrony ◽  
Real Life ◽  
Stimulus Onset ◽  
Time Interval ◽  
Decision Task ◽  
Cognitive Stability ◽  
Inter Trial Interval ◽  
The Stability ◽  
Onset Asynchrony

In real life, decisions are often naturally embedded in decision sequences. In contrast, in the laboratory, decisions are oftentimes analysed in isolation. Here, we investigated the influence of decision sequences in value-based decision making and whether the stability of such effects can be modulated. In our decision task, participants needed to collect rewards in a virtual two-dimensional world. We presented a series of two reward options that were either quick to collect but were smaller in value or took longer to collect but were larger in value. The subjective value of each option was driven by the options’ value and how quickly they could be reached. We manipulated the subjective values of the options so that one option became gradually less valuable over the course of a sequence, which allowed us to measure choice perseveration (i.e., how long participants stick to this option). In two experiments, we further manipulated the time interval between two trials (inter-trial interval), and the time delay between the onsets of both reward options (stimulus onset asynchrony). We predicted how these manipulations would affect choice perseveration using a computational attractor model. Our results indicate that both the inter-trial interval and the stimulus onset asynchrony modulate choice perseveration as predicted by the model. We discuss how our findings extend to research on cognitive stability and flexibility.

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