Impulsive Reaction-Diffusion Delayed Models in Biology: Integral Manifolds Approach

In this paper we study an impulsive delayed reaction-diffusion model applied in biology. The introduced model generalizes existing reaction-diffusion delayed epidemic models to the impulsive case. The integral manifolds notion has been introduced to the model under consideration. This notion extends the single state notion and has important applications in the study of multi-stable systems. By means of an extension of the Lyapunov method integral manifolds’ existence, results are established. Based on the Lyapunov functions technique combined with a Poincarè-type inequality qualitative criteria related to boundedness, permanence, and stability of the integral manifolds are also presented. The application of the proposed impulsive control model is closely related to a most important problems in the mathematical biology—the problem of optimal control of epidemic models. The considered impulsive effects can be used by epidemiologists as a very effective therapy control strategy. In addition, since the integral manifolds approach is relevant in various contexts, our results can be applied in the qualitative investigations of many problems in the epidemiology of diverse interest.

Influence of TTS Systems Performance on Reaction Times in People with Aphasia

Text-to-speech (TTS) systems provide fundamental reading support for people with aphasia and reading difficulties. However, artificial voices are more difficult to process than natural voices. The current study is an extended analysis of the results of a clinical experiment investigating which, among three artificial voices and a digitised human voice, is more suitable for people with aphasia and reading impairments. Such results show that the voice synthesised with Ogmios TTS, a concatenative speech synthesis system, caused significantly slower reaction times than the other three voices used in the experiment. The present study explores whether and what voice quality metrics are linked to delayed reaction times. For this purpose, the voices were analysed using an automatic assessment of intelligibility, naturalness, and jitter and shimmer voice quality parameters. This analysis revealed that Ogmios TTS, in general, performed worse than the other voices in all parameters. These observations could explain the significantly delayed reaction times in people with aphasia and reading impairments when listening to Ogmios TTS and could open up consideration about which TTS to choose for compensative devices for these patients based on the voice analysis of these parameters.

Level of neurotransmitters in neuroamine-containing lung structures in different forms of tuberculosis

The aim of the study was to identify the features of variations in the localization of monoamines (catecholamines, serotonin)in the cell structures of autopsy material of lungs affected by tuberculosis. Material and methods. 165 cases of secondary pulmonary tuberculosis were studied. We studied 2500 histological preparations of patients aged 30 to 55 years, divided into 5 groups, corresponding to the forms of secondary tuberculosis (group 1-acute focal tuberculosis, group 2-fibro-focal tuberculosis, group 3-infiltrative tuberculosis, group 4-acute cavernous tuberculosis, group 5 - fibro-cavernous tuberculosis. To selectively detect neuroamine-containing structures of the lungs and adrenergic nerve fibers, the Falk-Hillarp luminescence-histochemical method was used in the modification of E. M. Krokhina, based on the reaction of neuroamine condensation with formaldehyde. Results. When using the Falk-Hillarp luminescence-histochemical method, mycobacteria of tuberculosis containing catecholamines and serotonin were detected in autopsy material of lungs affected by a specific inflammatory process, as well as neuroamine-containing granular luminescent cells and mast cells. Affected and unaffected areas of the lungs contain different amounts of the studied monoamines. The results of the study revealed the dependence of the number of cells and the content of the studied bioamines in them on the form of secondary tuberculosis. It was found that in small forms of secondary tuberculosis (acute focal, fibrotic-focal), the number of cells and quantitative parameters of the studied neurotransmitters (catecholamines, serotonin) in granular luminescent cells and mast cells change in the direction of increase. In destructive processes in the lungs (acute cavernous and fibrous-cavernous tuberculosis), the content of catecholamines in the studied structures in the affected area prevails over the control. The concentration of serotonin in the studied cells of the area of lung tissue affected by the tuberculosis process is reduced. The number of neuroamine-containing cells is significantly reduced. The maximum luminescence of catecholamines and serotonin in granular luminescent cells was determined in the infiltrative form of tuberculosis. In mast cells, the highest content of catecholamines was found in the group of acute cavernous tuberculosis, and serotonin in the group of the infiltrative form of the disease. In stained sections of the lungs in this form of tuberculosis, a luminescent pathway of lymphocytes was found. The nerve fibers detected at the sites of mycobacteria were also changed. They did not have a clear luminescence, looked "swollen", in places they did not have varicose veins. Conclusion. Comparing the results of the study with the literature data, it was found that pulmonary tuberculosis occurs as a delayed reaction, and Mycobacterium tuberculosis manifests itself as a corpuscular antigen.

The effect of self-limiting on the prevention and control of the diffuse COVID-19 epidemic with delayed and temporal-spatial heterogeneous

Background The global spread of the novel coronavirus pneumonia is still continuing, and a new round of more serious outbreaks has even begun in some countries. In this context, this paper studies the dynamics of a type of delayed reaction-diffusion novel coronavirus pneumonia model with relapse and self-limiting treatment in a temporal-spatial heterogeneous environment. Methods First, focus on the self-limiting characteristics of COVID-19, incorporate the relapse and self-limiting treatment factors into the diffusion model, and study the influence of self-limiting treatment on the diffusion of the epidemic. Second, because the traditional Lyapunov stability method is difficult to determine the spread of the epidemic with relapse and self-limiting treatment, we introduce a completely different method, relying on the existence conditions of the exponential attractor of our newly established in the infinite-dimensional dynamic system to determine the diffusion of novel coronavirus pneumonia. Third, relapse and self-limiting treatment have led to a change in the structure of the delayed diffusion COVID-19 model, and the traditional basic reproduction number $$R_0$$ R 0 no longer has threshold characteristics. With the help of the Krein-Rutman theorem and the eigenvalue method, we studied the threshold characteristics of the principal eigenvalue and found that it can be used as a new threshold to describe the diffusion of the epidemic. Results Our results prove that the principal eigenvalue $$\uplambda ^{*}$$ λ ∗ of the delayed reaction-diffusion COVID-19 system with relapse and self-limiting treatment can replace the basic reproduction number $$R_0$$ R 0 to describe the threshold effect of disease transmission. Combine with the latest official data and the prevention and control strategies, some numerical simulations on the stability and global exponential attractiveness of the diffusion of the COVID-19 epidemic in China and the USA are given. Conclusions Through the comparison of numerical simulations, we find that self-limiting treatment can significantly promote the prevention and control of the epidemic. And if the free activities of asymptomatic infected persons are not restricted, it will seriously hinder the progress of epidemic prevention and control.

Stimulation of Tight Formation in Kazakhstan by Chelate Based Treatment Fluids

Stimulation systems have improved over past decades, yet challenges prevail in corrosion, unwanted precipitation and handling hazardous chemicals. The role of chelating agents in coping with such concerns, is undeniably positive: their limited corrosivity, effective metal control and outstanding HSE profile, make them effective acidizing alternatives. Particularly when seeking delayed reaction at high temperature or removing insoluble material like Barite, chelating agents like GLDA and DTPA respectively have been reported effective both at laboratory and field scale. Formulations based on abovementioned chelating agents were evaluated experimentally to assess potential stimulation of Kazakhstan formations. Core-plug samples used in this evaluation are predominantly carbonate rock originating from different wells. The coreflooding experiments were performed at HPHT conditions to assess performance of treatment fluids to a) create new flow-channels (wormholes) thus improving rock permeability, and b) remove BaSO4-based solids suspected to be affecting productivity in the field. In this work, five reservoir core plugs were stimulated by GLDA based formulation to assess wormholing mechanism, while two core-plugs were treated by DTPA based fluid to study the impact of matrix cleaning. The matrix cleaning properties of DTPA based fluid were investigated on the damaged core plugs which were artificially damaged by in-situ precipitation of BaSO4 scale. The coreflood study included injection of the preflush, the treatment fluid and the post-flush system at reservoir temperature of 270 °F and low injection rates to accommodate the low permeability of the formation. It was shown that GLDA based fluid can effectively stimulate the reservoir core samples. The effective mechanism was observed to be wormholing thus increasing rock permeability by over a thousand times. No signs of face dissolution were observed despite slow injection rate at such high temperature; something that was not possible when a fast reacting acid (i.e. HCl) was used under the same conditions. In addition, it was shown that the DTPA based fluid can efficiently improve the rock permeability through matrix cleaning by both Barium and Calcium chelation. In the first treatment test by this fluid system, around 45% of the damaged permeability was recovered. While in the second test, not only BaSO4 scale was dissolved but also the CaCO3 minerals were partly dissolved and the core permeability was significantly increased (Kf/Ki >200). Experimental results bring promising prognosis for field implementation despite expected low injectivity at high downhole temperature. GLDA treatments avoid premature acid spending and face dissolution - common outcomes of HCl- which translate into deeper extent of stimulation. Additionally, in barite damaged wells, DTPA treatment represents an attractive solution for damage reduction and by-passing. Finally, intrinsic properties of chelating agents reduce asset integrity risks, improve operation HSE and simplify flow-back handling.

A delayed reaction–diffusion viral infection model with nonlinear incidences and cell-to-cell transmission

In this paper, we propose a reaction–diffusion viral infection model with nonlinear incidences, cell-to-cell transmission, and a time delay. We impose the homogeneous Neumann boundary condition. For the case where the domain is bounded, we first study the well-posedness. Then we analyze the local stability of homogeneous steady states. We establish a threshold dynamics which is completely characterized by the basic reproduction number. For the case where the domain is the whole Euclidean space, we consider the existence of traveling wave solutions by using the cross-iteration method and Schauder’s fixed point theorem. Finally, we study how the speed of spread in space affects the spread of cells and viruses. We obtain the existence of the wave speed, which is dependent on the diffusion coefficient.

‘Full cause of weeping’: Affective Failure in The Queen (2006) and The Crown (2019)

This article reads The Crown, Series Three, Episode Three, ‘Aberfan’, as an adaptation of The Queen, both of which were written by Peter Morgan. Each focuses on a crisis in public relations emerging from Elizabeth II’s delayed reaction to a tragedy: the mining disaster in The Crown and the death of Princess Diana in The Queen. Both are double portraits, in which the monarch’s affective failure is contrasted with the more humane response of the prime minister, Harold Wilson and Tony Blair respectively. And both texts explore the tension between private grief and public performance. By reading these texts in dialogue, their relevance to their contemporary contexts is magnified. The Queen uses Elizabeth II’s nadir in public relations to comment on Blair’s fall from grace as a result of the Iraq War, while ‘Aberfan’, by emphasising the avoidable nature of the disaster, comments on the Grenfell Tower fire of 2017. While neither text shrinks from criticising the monarch for her breakdown in empathy, the resonances between Aberfan and Grenfell allow the Queen’s immediate and humane response in 2017 to redeem her delayed reactions in the past. This demonstrates the capacity of fictional texts to intervene in the popular perception of their subjects.

Assessment of labor intensity indicators and factors affecting fatigue in civil aviation pilots based on the results of a questionnaire

Introduction. An essential feature of the professional activity of pilots of civil aviation aircraft is the high intensity of work due to pronounced emotional, intellectual, and sensory loads, unique work modes. The study aims to assess the intensity of work and the prevalence of factors affecting fatigue among civil aviation pilots according to an anonymous online questionnaire. Materials and methods. Experts surveyed 667 members of the flight crews in remote anonymous online questioning. We developed the questionnaires under the criteria for assessing the intensity of work, assessing the risk factors for fatigue development according to the ICAO recommendations, and analyzing the pilot's activity algorithm. The researchers used descriptive statistical methods to analyze the survey data. Results. The working conditions of pilots according to 7 indicators of tension correspond to class 3.2: a high level of intellectual loads (72-100% of pilots), a large number of overlapping time zones (18%), the maximum duration of concentrated observation (70.7%), a high density of signals and messages (29.9%), a significant number of objects of simultaneous observation (18.9%), a high degree of risk to one's own life and responsibility for the safety of others (98%), as well as a rough working day (79%). According to the totality of indicators, the general class of labor intensity corresponds to the highest degree (class 3.3). The factors affecting the fatigue of pilots include rare rest between flights (44.6% of respondents), intermittent sleep (59.9%), not always a full sleep before the night flight shift (85.9%). According to the survey results, the share of pilots who have spontaneous sleep during the flight is 74.3%, and frequently delayed reaction to usual, non - standard, or extreme stimuli and signals is 12.3%. Conclusions. The obtained data of the questionnaire survey confirm the results of psychophysiological studies that have shown that the level of the labor intensity of pilots is "super-intense or extreme." Therefore, considering the prevalence of factors affecting fatigue among the crew members, and based on the understanding of the fundamental problems noted by the pilots, it is necessary to develop measures and management solutions to minimize the risk factors for fatigue development.