Subdiffusive search with home returns via stochastic resetting: A subordination scheme approach

Stochastic resetting with home returns is widely found in various manifestations in life and nature. Using the solution to the home return problem in terms of the solution to the corresponding problem without home returns [Pal et al. Phys. Rev. Research 2, 043174 (2020)], we develop a theoretical framework for search with home returns in the case of subdiffusion. This makes a realistic description of restart by accounting for random walks with random stops. The model considers stochastic processes, arising from Brownian motion subordinated by an inverse infinitely divisible process (subordinator).

In the Labyrinth of Forgetfulness: Charley Grainger’s Joycean Journey in Christine Dwyer Hickey’s Cold Eye of Heaven

Cold Eye of Heaven (2011) shows pre-Brexit Dublin steeped in the post-Celtic Tiger anxieties. The novel narrates the life of a contemporary Everyman, Charley Grainger, known as Farley, from his final moments back to his childhood. Thus, Farley’s journey envisages both a Joycean interior monologue depicting his old-age bafflement in the meanders of memory and a realistic description of the character’s bewilderment at the changes in the cityscapes of the Dublin of 2010. The present paper is a comparative study of the first two chapters of the novel in reference to the history of the city present in the entire text, through the use of the tropes of the mental and urbane labyrinths. Imbued with the allusions to current reality, i.e., the presence of immigrants, Hickey’s observations are in line with Joycean anti-nationalism, as the story offers a nostalgia-stricken picture of the inevitable economic transformation of the metropolis.

OMEN-SED(-RCM) (v1.1): a pseudo-reactive continuum representation of organic matter degradation dynamics for OMEN-SED

The Organic Matter ENabled SEDiment model (OMEN-SED) is a one-dimensional, analytical reaction–transport model for early diagenesis in marine sediments. It explicitly resolves organic matter (OM) degradation and associated biogeochemical terminal electron acceptor, reduced species and nutrient dynamics in porous media under steady-state conditions. OMEN-SED has been specifically designed for coupling to global Earth system models and the analytical solution of the coupled set of mass conservation equations ensures the computational efficiency required for such a coupling. To find an analytical solution, OMEN-SED expresses all explicitly resolved biogeochemical processes as a function of OM degradation. The original version of OMEN-SED contains a relatively simple description of OM degradation based on two reactive OM classes, a so-called 2G model. However, such a simplified approach does not fully account for the widely observed continuous decrease in organic matter reactivity with burial depth/time. The reactive continuum model that accounts for the continuous distribution of organic compounds over the reactive spectrum represents an alternative and more realistic description but cannot be easily incorporated within the general OMEN-SED framework. Here, we extend the diagenetic framework of OMEN-SED with a multi-G approximation of the reactive continuum model (RCM) of organic matter degradation by using a finite but large number of OM fractions, each characterized by a distinct reactivity. The RCM and its multi-G approximation are fully constrained by only two free parameters, a and ν, that control the initial distribution of OM compounds over the reactivity spectrum. The new model is not only able to reproduce observed pore water profiles, sediment–water interface fluxes and redox zonation across a wide range of depositional environments but also provides a more realistic description of anaerobic degradation pathways. The added functionality extends the applicability of OMEN-SED to a broader range of environments and timescales, while requiring fewer parameters to simulate a wider spectrum of OM reactivities.

Modeling galvanostatic charge–discharge of nanoporous supercapacitors

Molecular modeling has been considered indispensable in studying the energy storage of supercapacitors at the atomistic level. The constant potential method (CPM) allows the electric potential to be kept uniform in the electrode, which is essential for a realistic description of the charge repartition and dynamics process in supercapacitors. However, previous CPM studies have been limited to the potentiostatic mode. Although widely adopted in experiments, the galvanostatic mode has rarely been investigated in CPM simulations because of a lack of effective methods. Here we develop a modeling approach to simulating the galvanostatic charge–discharge process of supercapacitors under constant potential. We show that, for nanoporous electrodes, this modeling approach can capture experimentally consistent dynamics in supercapacitors. It can also delineate, at the molecular scale, the hysteresis in ion adsorption–desorption dynamics during charging and discharging. This approach thus enables the further accurate modeling of the physics and electrochemistry in supercapacitor dynamics.

Period of Arrhythmia Anchored around an Infarction Scar in an Anatomical Model of the Human Ventricles

Rotating nonlinear waves of excitation in the heart cause dangerous cardiac arrhythmias. Frequently, ventricular arrhythmias occur as a result of myocardial infarction and are associated with rotation of the waves around a post-infarction scar. In this paper, we perform a detailed in silico analysis of scroll waves in an anatomical model of the human ventricles with a generic model of the infarction scar surrounded by the gray zone with modified properties of the myocardial tissue. Our model includes a realistic description of the heart shape, anisotropy of cardiac tissue and a detailed description of the electrical activity in human ventricular cells by a TP06 ionic model. We vary the size of the scar and gray zone and analyze the dependence of the rotation period on the injury dimensions. Two main regimes of wave scrolling are observed: the scar rotation, when the wave rotates around the scar, and the gray zone rotation, when the wave rotates around the boundary of the gray zone and normal tissue. The transition from the gray zone to the scar rotation occurs for the width of gray zone above 10–20 mm, depending on the perimeter of the scar. We compare our results with simulations in 2D and show that 3D anisotropy reduces the period of rotation. We finally use a model with a realistic shape of the scar and show that our approach predicts correctly the period of the arrhythmia.

Tra corte, casa e monastero La vita di una donna nel Giappone del Medioevo

In Japanese history the establishment of the ie, or family system, on which patriarchal authority was based, represents one of the most important turning points. The ie that came into being from the late eleventh century onwards, differs from the uji that had characterised previous eras, not so much on account of its patriarchal system but because it would place the married couple in prime position. The family, previously made up of a man engaging in occasional relationships with a number of women, would gradually become a more stable nucleus comprising of a husband with a wife who enjoyed a legally recognised position of privilege compared with all the other concubines. After her husband’s death, she would naturally become a sort of substitute figure, often gaining considerable authority and prestige. With the threat of the Mongolian invasions (from 1274 and 1281) and the consequent increase in limitations on women’s inheritance rights, many widows were forced to take vows as a sign of loyalty and tangible proof of their choice not to remarry if they were to secure their husband’s property. The literary production of Nun Abutsu (1225 ca.-1283 ca.) written in a period which led to the inevitable breakdown of the economic, social, and political balance of Japan, offers a realistic description of women’s ambitions, duties and concerns in an era of great transformation. In a close reading of her major works Abutsu no fumi (The letter of Abutsu, 1264 ca.), Utatane (Fitful slumbers, XIII century) and Izayoi nikki (The Diary of the sixteenth night moon, 1280 ca.), the book casts light on some important issues in Japanese women’s history: the gradual shift from uxorical to virilocal marriage, the consequences of this process for inheritance patterns, the meaning of women’s participation in the intellectual life of their time.

A Quantitative Model for Optical Coherence Tomography

Optical coherence tomography (OCT) is a widely used imaging technique in the micrometer regime, which gained accelerating interest in medical imaging in the last twenty years. In up-to-date OCT literature, certain simplifying assumptions are made for the reconstructions, but for many applications, a more realistic description of the OCT imaging process is of interest. In mathematical models, for example, the incident angle of light onto the sample is usually neglected or a plane wave description for the light–sample interaction in OCT is used, which ignores almost completely the occurring effects within an OCT measurement process. In this article, we make a first step to a quantitative model by considering the measured intensity as a combination of back-scattered Gaussian beams affected by the system. In contrast to the standard plane wave simplification, the presented model includes system relevant parameters, such as the position of the focus and the spot size of the incident laser beam, which allow a precise prediction of the OCT data. The accuracy of the proposed model—after calibration of all necessary system parameters—is illustrated by simulations and validated by a comparison with experimental data obtained from a 1300 nm nswept-source OCT system.

The Potential of Simulating Energy Systems: The Multi Energy Systems Simulator Model

Energy system modelling is an essential practice to assist a set of heterogeneous stakeholders in the process of defining an effective and efficient energy transition. From the analysis of a set of open-source energy system models, it emerged that most models employ an approach directed at finding the optimal solution for a given set of constraints. On the contrary, a simulation model is a representation of a system used to reproduce and understand its behaviour under given conditions without seeking an optimal solution. In this paper, a new open-source energy system model is presented. Multi Energy Systems Simulator (MESS) is a modular, multi-energy carrier, multi-node model that allows the investigation of non optimal solutions by simulating an energy system. The model was built for urban level analyses. However, each node can represent larger regions allowing wider spatial scales to be represented as well. In this work, the tool’s features are presented through a comparison between MESS and Calliope, a state of the art optimization model, to analyse and highlight the differences between the two approaches, the potentialities of a simulation tool and possible areas for further development. The two models produced coherent results, showing differences that were tracked down to the different approaches. Based on the comparison conducted, general conclusions were drawn on the potential of simulating energy systems in terms of a more realistic description of smaller energy systems, lower computational times and increased opportunity for participatory processes in planning urban energy systems.

Lattice Boltzmann simulations on the tumbling to tank-treading transition: effects of membrane viscosity

The tumbling to tank-treading (TB-TT) transition for red blood cells (RBCs) has been widely investigated, with a main focus on the effects of the viscosity ratio λ (i.e., the ratio between the viscosities of the fluids inside and outside the membrane) and the shear rate γ ˙ applied to the RBC. However, the membrane viscosity μ m plays a major role in a realistic description of RBC dynamics, and only a few works have systematically focused on its effects on the TB-TT transition. In this work, we provide a parametric investigation on the effect of membrane viscosity μ m on the TB-TT transition for a single RBC. It is found that, at fixed viscosity ratios λ , larger values of μ m lead to an increased range of values of capillary number at which the TB-TT transition occurs; moreover, we found that increasing λ or increasing μ m results in a qualitatively but not quantitatively similar behaviour. All results are obtained by means of mesoscale numerical simulations based on the lattice Boltzmann models. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

Plague and Literature in Western Europe, from Giovanni Boccaccio to Albert Camus

In medieval times the plague hit Europe between 1330 and 1350. The Italian novelist Giovanni Boccaccio, one of the exponents of the cultural movement of Humanism, in the introduction (proem) of his “Decameron” described the devastating effects of the ‘black plague’ on the inhabitants of the city of Florence. The pestilence returned to Western Europe in several waves, between the 16th and 17th centuries. William Shakespeare in “Romeo and Juliet” and other tragedies, and Ben Jonson in “The Alchemist” made several references to the plague, but they did not offer any realistic description of that infective disease. Some decennials later Daniel Defoe, in his “A Journal of the Plague Year” (1719), gave a detailed report about the ‘Great Plague’ which hit England in 1660, based on documents of the epoch. In more recent times, Thomas S. Eliot, composing his poem “The Waste Land” was undoubtedly influenced by the spreading of another infective disease, the so-called “Spanish flu”, which affected him and his wife in December 1918. Some decennials later, the French writer and philosopher Albert Camus, in his novel “The Plague”, symbolized with a plague epidemic the war which devastated Europe, North Africa and the Far East from 1937 to 1945, extolling a death toll of over 50 million victims. Those literary works offered a sort of solace to the lovers of literature. To recall them is the purpose of the present paper, in these years afflicted by the spreading of the Covid-19 Pandemic.