Short-Time Critical Dynamics of Damage Spreading in the Two-Dimensional Ising Model

The short-time critical dynamics of propagation of damage in the Ising ferromagnet in two dimensions is studied by means of Monte Carlo simulations. Starting with equilibrium configurations at $T= \infty$ and magnetization $M=0$, an initial damage is created by flipping a small amount of spins in one of the two replicas studied. In this way, the initial damage is proportional to the initial magnetization $M_0$ in one of the configurations upon quenching the system at $T_C$, the Onsager critical temperature of the ferromagnetic-paramagnetic transition. It is found that, at short times, the damage increases with an exponent $\theta_D=1.915(3)$, which is much larger than the exponent $\theta=0.197$ characteristic of the initial increase of the magnetization $M(t)$. Also, an epidemic study was performed. It is found that the average distance from the origin of the epidemic ($\langle R^2(t)\rangle$) grows with an exponent $z^* \approx \eta \approx 1.9$, which is the same, within error bars, as the exponent $\theta_D$. However, the survival probability of the epidemics reaches a plateau so that $\delta=0$. On the other hand, by quenching the system to lower temperatures one observes the critical spreading of the damage at $T_{D}\simeq 0.51 T_C$, where all the measured observables exhibit power laws with exponents $\theta_D = 1.026(3)$, $\delta = 0.133(1)$, and $z^*=1.74(3)$.Comment: 11 pages, 9 figures (included). Phys. Rev. E (2010), in press

Damage Spreading in a Driven Lattice Gas Model

We studied damage spreading in a Driven Lattice Gas (DLG) model as a function of the temperature $T$, the magnitude of the external driving field $E$, and the lattice size. The DLG model undergoes an order-disorder second-order phase transition at the critical temperature $T_c(E)$, such that the ordered phase is characterized by high-density strips running along the direction of the applied field; while in the disordered phase one has a lattice-gas-like behaviour. It is found that the damage always spreads for all the investigated temperatures and reaches a saturation value $D_{sat}$ that depends only on $T$. $D_{sat}$ increases for $TT_c(E=\infty)$ and is free of finite-size effects. This behaviour can be explained as due to the existence of interfaces between the high-density strips and the lattice-gas-like phase whose roughness depends on $T$. Also, we investigated damage spreading for a range of finite fields as a function of $T$, finding a behaviour similar to that of the case with $E=\infty$.Comment: 13 pages, 7 figures. Submitted to "Journal of Statistical Mechanics: Theory and Experiment

Nanofabrication by self-assembly

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The impact of the COVID-19 pandemic on forensic mental health services and clinical outcomes: A longitudinal study

Copyright © 2022 Puzzo, Aldridge-Waddon, Stokes, Rainbird and Kumari. Background The COVID-19 pandemic has had a substantial impact on forensic mental health services provision and implementation. This study aimed to provide an analysis of the impact of COVID-19 related restrictions on routine outcomes within a large forensic mental service in London, UK. Method We conducted a longitudinal cohort study using routinely collected data-sets pre (April 2018 - March 2020) and during the pandemic (March 2020 – March 2021; lockdown periods, January-March 2021, 8th March-May 2020; January-March 2021). We used causal impact models (Bayesian structural time-series) to examine the effect of the COVID-19 related changes in service provision and implementation routine outcomes. Results There was an overall increase in long-term segregation (LTS) hours during the pandemic; 130%, (95% Cl 87%, 171%) during Lockdown 1; 113%, (95% Cl 74%, 151%) during post-Lockdown 1; 157% (95% Cl 116%, 197%) during Lockdown 2 and, finally, 69% (95% Cl 49%, 92%) during Lockdown 3. Non-physical assaults to staff decreased, (-41%, 95% Cl -83%, 0.97%) during Lockdown 1. Physical assaults to staff decreased (-48%, 95% CI -92%, 6.1%) but physical and non-physical assaults to service users (199%, 95% CI 57%, 355%), (199%, 95% CI 59%, 345%), self-harm (325%, 95% Cl 137%, 487%) and enforced medication (140%, 95% Cl 48%, 224%) all increased during Lockdown 3. Overall, the most negative outcome was evident during Lockdown 3. Conclusion The pandemic and its related restrictions have negatively affected some service outcomes resulting in increased incidents of violence and increase in some restrictive interventions beyond what would have been expected had the pandemic not happened

Clarifying the Roles of Schizotypy and Psychopathic Traits in Lexical Decision Performance

Brunel University London College of Health, Medicine, and Life Sciences Doctoral Scholarships; Erasmus Mobility programm

Scenario-specific aberrations of social reward processing in dimensional schizotypy and psychopathy

Data availability: The datasets generated and/or analysed for the investigations reported in this paper are available in the OSF repository, https://osf.io/fp6qb/, https://doi.org/10.17605/OSF.IO/FP6QB.Copyright © The Author(s) 2022. The feelings of reward associated with social interaction help to motivate social behaviour and influence preferences for different types of social contact. In two studies conducted in a general population sample, we investigated self-reported and experimentally-assessed social reward processing in personality spectra with prominent interpersonal features, namely schizotypy and psychopathy. Study 1 (n = 154) measured social reward processing using the Social Reward Questionnaire, and a modified version of a Monetary and Social Incentive Delay Task. Study 2 (n = 42; a subsample of Study 1) investigated social reward processing using a Social Reward Subtype Incentive Delay Task. Our results show that schizotypy (specifically Cognitive-Perceptual dimension) and psychopathy (specifically Lifestyle dimension) are associated with diverging responses to social scenarios involving large gatherings or meeting new people (Sociability), with reduced processing in schizotypy and heightened processing in psychopathy. No difference, however, occurred for other social scenarios—with similar patterns of increased antisocial (Negative Social Potency) and reduced prosocial (Admiration, Sociability) reward processing across schizotypy and psychopathy dimensions. Our findings contribute new knowledge on social reward processing within these personality spectra and, with the important exception of Sociability, highlight potentially converging patterns of social reward processing in association with schizotypy and psychopathy.L.A.W and M.V. were supported by Brunel University London College of Health, Medicine, and Life Sciences Doctoral Scholarships and L.E. was supported by Erasmus+ programme

Order-disorder criticality, wetting, and morphological phase transitions in the irreversible growth of far-from-equilibrium magnetic films

An exhaustive numerical investigation of the growth of magnetic films in confined $(d+1)$-dimensional stripped geometries ($d=1,2$) is carried out by means of extensive Monte Carlo simulations. Thin films in contact with a thermal bath are grown by adding spins with two possible orientations and considering ferromagnetic (nearest-neighbor) interactions. At low temperatures, it is observed that the films exhibit ``spontaneous magnetization reversals'' during the growth process. Furthermore, it is found that for $d=1$ the system is non-critical, while a continuous order-disorder phase transition at finite temperature takes place in the $d=2$ case. Using standard finite-size scaling procedures, the critical temperature and some relevant critical exponents are determined. Finally, the growth of magnetic films in $(2+1)$ dimensions with competing short-range magnetic fields acting along the confinement walls is studied. Due to the antisymmetric condition considered, an interface between domains with spins having opposite orientation develops along the growing direction. Such an interface undergoes a localization-delocalization transition that is the precursor of a wetting transition in the thermodynamic limit. Furthermore, the growing interface also undergoes morphological transitions in the growth mode. A comparison between the well-studied equilibrium Ising model and the studied irreversible magnetic growth model is performed throughout. Although valuable analogies are encountered, it is found that the nonequilibrium nature of the latter introduces new and rich physical features of interest.Comment: 23 pages, 10 figure

Distinct neural signatures of schizotypy and psychopathy during visual word-nonword recognition

Data availability statement: The data used in this study are available from the corresponding author upon reasonable request.Copyright © 2022 The Authors. Previous behavioural data indicate lower word-nonword recognition accuracy in association with a high level of positive schizotypy, psychopathy, or motor impulsivity traits, each with some unique contribution, in the general population. This study aimed to examine the neural underpinnings of these associations using functional magnetic resonance imaging (fMRI) in a volunteer sample. Twenty-two healthy English-speaking adults completed self-report measures of schizotypy (Oxford-Liverpool Inventory of Feelings and Experiences [O-LIFE]), psychopathy (Triarchic Psychopathy Measure [TriPM]), and impulsivity (Barratt Impulsiveness Scale [BIS-11]) and underwent whole-brain fMRI while performing a lexical decision task (LDT) featuring high and low-frequency words, real nonwords, and pseudohomophones. Higher positive schizotypy (Unusual Experiences) was associated with lower cerebellum activity during identification of low-frequency words (over real nonwords). Higher Boldness (fearless dominance) and Meanness (callous aggression) facets of psychopathy were associated with lower striatal and posterior cingulate activity when identifying nonwords over words. Higher Motor Impulsivity was associated with lower activity in the fusiform (bilaterally), inferior frontal (right-sided), and temporal gyri (bilaterally) across all stimuli-types over resting baseline. Positive schizotypy, psychopathy, and impulsivity traits influence word-nonword recognition through distinct neurocognitive mechanisms. Positive schizotypy and psychopathy appear to influence LDT performance through brain areas that play only a supportive (cerebellum) or indirect role in reading-related skills. The negative association between Motor Impulsivity and activations typically found for phonological processing and automatic word identification indicates a reduced bilateral integration of the meaning and sound of mental word representations, and inability to select the appropriate outputs, in impulsive individuals.This research received no specific grant from any funding agency, commercial or not-for-profit sectors

Damage Spreading at the Corner Filling Transition in the two-dimensional Ising Model

The propagation of damage on the square Ising lattice with a corner geometry is studied by means of Monte Carlo simulations. It is found that, just at $T=T_f (h)$ (critical temperature of the filling transition) the damage initially propagates along the interface of the competing domains, according to a power law given by $D(t) \propto t^{\eta}$. The value obtained for the dynamic exponent ($\eta^{*} = 0.89(1)$) is in agreement with that corresponding to the wetting transition in the slit geometry (Abraham Model) given by $\eta^{WT} = 0.91(1)$. However, for later times the propagation crosses to a new regime such as $\eta^{**} = 0.40 \pm 0.02$, which is due to the propagation of the damage into the bulk of the magnetic domains. This result can be understood due to the constraints imposed to the propagation of damage by the corner geometry of the system that cause healing at the corners where the interface is attached.Comment: 22 pages, including figures Submited to J. Phys.: Condens. Matte