Dynamical Recovery of Complex Networks under a Localised Attack

In real systems, some damaged nodes can spontaneously become active again when recovered from themselves or their active neighbours. However, the spontaneous dynamical recovery of complex networks that suffer a local failure has not yet been taken into consideration. To model this recovery process, we develop a framework to study the resilience behaviours of the network under a localised attack (LA). Since the nodes’ state within the network affects the subsequent dynamic evolution, we study the dynamic behaviours of local failure propagation and node recoveries based on this memory characteristic. It can be found that the fraction of active nodes switches back and forth between high network activity and low network activity, which leads to the spontaneous emergence of phase-flipping phenomena. These behaviours can be found in a random regular network, Erdős-Rényi network and Scale-free network, which shows that these three types of networks have the same or different resilience behaviours under an LA and random attack. These results will be helpful for studying the spontaneous recovery real systems under an LA. Our work provides insight into understanding the recovery process and a protection strategy of various complex systems from the perspective of damaged memory.

Unsteady Mhd Stagnation-point Flow of Fractional Oldroyd-b Fluid Over a Stretching Sheet with Modified Fractional Fourier's Law

The aim of the article is to research the unsteady magnetohydrodynamic stagnation-point flow of fractional Oldroyd-B fluid over a stretched sheet. According to the distribution characteristics of pressure and magnetic field near the stagnation point, the momentum equation based on fractional Oldroyd-B constitutive model is derived. Moreover, the modified fractional Fourier's law considering thermal relaxation-retardation time is proposed, which applies in both the energy equation and the boundary condition of convective heat transfer. New finite difference scheme combined with L1 algorithm is established to solve the governing equations, whose convergence is confirmed by constructing the exact solution. The results indicate that the larger relaxation parameters of velocity block the flow, yet the retardation parameters of velocity show the opposite trend. It is particularly worth mentioning that all the temperature profiles first go up slightly to a maximal value and then descend markedly, which presents the thermal retardation characteristic of Oldroyd-B fluid. Additionally, under the effects of temperature's retardation and relaxation parameters, the intersection of the profiles far away from stretching sheet demonstrates the thermal memory characteristic.

A behavioural modelling approach to assess the impact of COVID-19 vaccine hesitancy

In this paper we introduce a compartmental epidemic model describing the transmission of the COVID-19 disease in presence of non-mandatory vaccination. The model takes into account the hesitancy and refusal of vaccination. To this aim, we employ the information index, which mimics the idea that individuals take their decision on vaccination based not only on the present but also on the past information about the spread of the disease. Theoretical analysis and simulations show clearly as a voluntary vaccination can certainly reduce the impact of the disease but it is unable to eliminate it. We also show how the information-related parameters affect the dynamics of the disease. In particular, the hesitancy and refusal of vaccination is better contained in case of large information coverage and small memory characteristic time. Finally, the possible influence of seasonality is also investigated.

Shereshevsky’s Case: A Reflection on the Peculiarities of Human Memory

The article deals with the problem of hyper-memory and two main mechanisms of its development: the mechanism of the ultimate development of analogization, schematization and algorithmization and the mechanism of escape from reality to the sphere of the imaginary by rejecting logical generalization and increasing the imaginative component of thinking. Based on the understanding of the effecti­veness of memory according to Korsakov, the author compares the features of mechanical memorization, characteristic of artificial devices and systems, and the cases of hyper-memory development in humans, especially highlighting the case of Shereshevsky as a case of the most pronounced and comprehensive hypermnesia. The article highlights the features of the memory of a phenomenal mnemonist distinguishing it from the memory of an ordinary person, and from the “memory” of external storage devices. The author analyzes the features of the mechanisms of information fixation and reproduction in the case of Shere­shevsky, presented in the works of Luria and Leontiev, as well as the areas and features of the manifestation of phenomenal memory in other cases of “regional hyper-memory” (genius, hyperthymnesia, Savant syndrome). The author con­cludes that in the case of general hypermnesia, characteristic of Shereshevsky, the memorization procedure is associated with the obligatory “separation from real­ity” and the replacement of the plan of the real with the plan of the imaginary, but the condition for the possibility of such replacement is the maximum reduction of the “higher type” memory associated with logical operations and abstraction, as well as the rejection of the principle of arbitrariness of the sign. The author comes to the conclusion that the direction of development of human hyper-memory, characteristic of the case of Shereshevsky and based on imaginative-emotional perception, is directly opposite to the artificial type of memory mechanism.

Flexible Resistive Switching Memory Devices Based on Graphene Oxide Polymer Nanocomposite

Flexible resistive switching memory devices based on graphene oxide (GO) polymer nanocomposite were prepared on flexible substrate to research the influence of bending on resistive switching behavior. The devices showed evident response in resistive switching memory characteristics to flexible bending. The 2000 cycles flexible bending leads to the switch of resistive switching memory characteristic from write-once-read-many time memory (WORM) to static random access memory (SRAM). Both WORM and SRAM memory properties are all repeatable, and the threshold switching voltage also showed good consistency. The resistive switching mechanism is attributed to the formation of carbon-rich conductive filaments for nonvolatile WORM characteristics. The bending-induced micro-crack may be responsible for the partial broken of the electrical channels, and may lead to the volatile SRAM characteristics.

THE ONEIRIC SPACE OF KAZUO ISHIGURO’S NOVEL ‘THE BURIED GIANT’

The article provides a detailed study of the fictional space of Kazuo Ishiguro’s novel The Buried Giant. There are identified the features that give this aspect of the chronotope of the novel an oneiric character. Particular attention is paid to the analysis of certain loci of the novel’s fictional space, their toponymic and semiotic characteristics. Among the artistic means that actualize the oneiric space in the text, there are distinguished the peculiarities of the narrative level (first-person narration, representation of the events through the consciousness of the characters) and the features of the artistic expression and visualization of the novel’s fictional world: incorporation of mythological elements, metaphorization and generalization of the fictional space, emphasis on its horizontal and vertical organization. Some of the mythological characters are considered in the paper in terms of the additional meanings they contribute to the novel. Some motifs actualized by incorporation of mythological elements are also examined. A comprehensive analysis allowed us to reveal that the oneiric nature determines the topological characteristics of the novel. In addition, the oneiric space in The Buried Giant performs the function of representing the work of mnemonic mechanisms, which determines the connection of the considered aspect of poetics with the author’s intention, as well as with the theme of memory, characteristic not only of the analyzed novel but of the writer’s works as a whole. The study has also revealed an analogy in the representation of the chronotope with previous works by Kazuo Ishiguro, which allows us, among other things, to conclude that the actualization of the oneiric space is an important feature of the author’s artistic method.

Fractal Analysis of the Long-Term Memory in Precipitation over Bénin (West Africa)

This study analyzed the long-term memory (LTM) in precipitation over Bénin synoptic stations from 1951 to 2010 using the detrended fluctuation analysis (DFA) method. Results reveal the existence of positive long-term memory characteristic in rainfall field. DFA exponent values are different regarding the concerned synoptic stations, reflecting the effect of geographical position and climate on the LTM. These values were related to the type of climate. The best DFA1-4 method depends on the geographical position of the studied station. However, DFA2 is generally the best in terms of spatial average from DFA1 to DFA4. In Bénin synoptic stations, except the Parakou station, the long-term temporal correlations are systematically the source of multifractality in rainfall. Except Natitingou, the strength of long-term memory characteristic decreases each twenty years in the study period. Considering the fractal approach, our results show that the subperiod 1991–2010 is not really a transition period as shown before. Thus, the drought is prolonging until 2010. So, fractal theory reveals more Bénin climatic characteristics.