Noise-induced escape in an excitable system

We consider the stochastic dynamics of escape in an excitable system, the FitzHugh-Nagumo (FHN) neuronal model, for different classes of excitability. We discuss, first, the threshold structure of the FHN model as an example of a system without a saddle state. We then develop a nonlinear (nonlocal) stability approach based on the theory of large fluctuations, including a finite-noise correction, to describe noise-induced escape in the excitable regime. We show that the threshold structure is revealed via patterns of most probable (optimal) fluctuational paths. The approach allows us to estimate the escape rate and the exit location distribution. We compare the responses of a monostable resonator and monostable integrator to stochastic input signals and to a mixture of periodic and stochastic stimuli. Unlike the commonly used local analysis of the stable state, our nonlocal approach based on optimal paths yields results that are in good agreement with direct numerical simulations of the Langevin equation

Colorectal reconstructions following Hartmann’s procedure: challenges and solutions

The availability of a stoma after Hartmann’s procedure significantly limits the patient’s ability to work and worsens the quality of his/her life, as it partially isolates him/her from society. Performing plastic colon surgeries is challenging due to the active formation of intestinal adhesions and low rectal stump. At present many different devices, equipment, operating methods, and techniques have been proposed for reconstructive surgery on the colon. However, the issues of access to the surgical area, providing constant visual control, both at the stage of isolation for the short stump of the rectum in the narrow pelvis and in formation process of low colorectal anastomosis, are not covered in the scientific publications

On the Huygens principle in the Puu model

We consider the macroeconomic model of T. Puu, describing the fluctuations of gross income in a given regio

On the stability of stationary solutions in diffusion models of oncological processes

We prove a sufficient condition for the stability of a stationary solution to a system of nonlinear partial differential equations of the diffusion model describing the growth of malignant tumors. We also numerically simulate stable and unstable scenarios involving the interaction between tumor and immune cell

Юбилей Владимира Михайловича Бенсмана (18 ноября 1927)

The article presents a brief biography of an outstanding surgeon and a scientist of the Kuban region in 20th and 21st centuries Dr. Vladimir Bensman (11/18/1927). It is dedicated to his 95th anniversary. 72 years of his professional life were dedicated to medical science and national health care!В статье представлена краткая биография выдающегося хирурга Кубани XX–XXI столетий Владимира Михайловича Бенсмана (18.11.1927). Статья приурочена к 95-летнему юбилею ученого, 72 года из которых проведены в служении медицинской науке и отечественному здравоохранению

Advances in and Issues With Minimally Invasive Surgery for Rectal Cancer in Elderly Patients

Colorectal cancer ranks third after breast cancer in terms of incidence and second after lung cancer in terms of mortality.Management of rectal cancer requires a multidisciplinary approach, with the surgical management playing the main role. There are currently three resective techniques that complement the traditional open surgery: laparoscopic surgery, robotic surgery, and transanal total mesorectal excision.Rectal cancer in elderly patients is particularly hard to diagnose and treat surgically due to multiple comorbidities and limited functional reserve. Treatment of such patients may be associated with poorer outcomes after both open and minimally invasive surgery.This article reviews the current state of advances in minimally invasive surgery for rectal cancer in general and in elderly patients in particular

Generalized compactness in linear spaces and its applications

The class of subsets of locally convex spaces called $\mu$-compact sets is considered. This class contains all compact sets as well as several noncompact sets widely used in applications. It is shown that many results well known for compact sets can be generalized to $\mu$-compact sets. Several examples are considered. The main result of the paper is a generalization to $\mu$-compact convex sets of the Vesterstrom-O'Brien theorem showing equivalence of the particular properties of a compact convex set (s.t. openness of the mixture map, openness of the barycenter map and of its restriction to maximal measures, continuity of a convex hull of any continuous function, continuity of a convex hull of any concave continuous function). It is shown that the Vesterstrom-O'Brien theorem does not hold for pointwise $\mu$-compact convex sets defined by the slight relaxing of the $\mu$-compactness condition. Applications of the obtained results to quantum information theory are considered.Comment: 27 pages, the minor corrections have been mad

EFFECT OF PHOTON TREATMENT ON STRUCTURE OF NIOBIUM OXIDE FILMS

In this work, we investigate changes in the phase composition, morphology, and structural changes during the photonic treatment of films obtained in the process of ion-beam sputtering of an Nb2O5 target. It was found that the initial films have an amorphous structure; at an irradiation energy of ~ 1.Работа была выполнена при поддержке государственного задания (N FZGM-2020-0007)

Хирургическое лечение высоких несформированных тощекишечных свищей методом отключения из заднебокового доступа

Objective. The aim of the study was to develop the safest technique for surgical disconnection of high, unformed jejunal fistulas, so as to avoid problems with detection the intestine leading to the fistula and to avoid complications of viscerolysis.Material and methods. The authors present their experience in surgical management of 35 patients with high delimited unformed debilitating jejunal fistulas. Of these, 22 patients were included in the comparison group; their fistulas were closed or disconnected with the known methods. Findings obtained from other 172 patients with adhesive intestinal obstruction after infectious complications of laparotomic wounds and topography of visceroparietal planar adhesions of the peritoneum were analyzed. After studying the nature and location of visceroparietal adhesions, the authors could develop a technique for proximal disconnection of high delimited unformed debilitating jejunal fistulas using posterolateral access which was applied in 13 patients from the studied group.Research results. The proposed technique of unilateral disconnection of high unformed jejunal fistulas reduces duration, damage and risk of prolonged bowel deserosing. As a result, a significant decrease in postoperative mortality from 59.1 ± 9.2% to 23.1 ± 11.2% (t=2.5; p<0.05) was registered. Due to the preoperative endoscopic marking showing direction to the fistula of intestinal loop and duodenojejunal junction, intraoperative orientation was more accurate and took much less time than in the comparison group. The posterolateral surgical approach to the fistula in the jejunal loop reduced the risk of its damage, since there was no need for extensive enterolysis anymore. Therefore, postoperative period in patients of the studied group was better and with fewer complications than in the comparison group.Conclusion. The posterolateral access prevented extended viscerolysis and allowed to put a reliable and atraumatic interintestinal anastomosis so as to disconnect the fistula. The unilateral disconnection of the jejunal fistula at postoperative intestinal paresis unloaded the interintestinal anastomosis, similar to Meidl’s definitive jejunostomy. The abovementioned positive aspects of the proposed surgical intervention allowed to significantly decrease postoperative complications and mortality rate, if to compare with outcomes after known surgical interventions with a similar purpose.Цель исследования – разработка наиболее безопасного способа хирургического отключения высоких несформированных тощекишечных свищей, лишенного трудностей обнаружения, приводящей к свищу кишки, и осложнений висцеролиза.Материал и методы исследования. Представлен опыт хирургического лечения 35 больных высокими отграниченными несформированными истощающими тощекишечными свищами. Из них 22 пациентам, вошедшим в группу сравнения, свищи закрывали или отключали известными способами. На материале хирургического лечения других 172 больных спаечной кишечной непроходимостью, перенесших инфекционные осложнения со стороны лапаротомных ран, изучена топография висцеро-париетальных плоскостных спаек брюшины. Результаты изучения природы и расположения висцеро-париетальных спаек позволили разработать способ проксимального отключения высоких отграниченных несформированных истощающих тощекишечных свищей из заднебокового доступа, который был применен у 13 больных, вошедших в основную группу наблюдения.Результаты. Предложенный способ одностороннего отключения высоких несформированных тощекишечных свищей уменьшил продолжительность, травматичность вмешательства и риск протяженного десерозирования кишечника. Результатом явилось достоверное снижение послеоперационной летальности с 59,1 ± 9,2 до 23,1 ± 11,2 % (t = 2,5; p < 0,05). Благодаря предоперационной эндоскопической маркировке, приводящей к свищу кишечной петли и дуодено-еюнального перехода, интраоперационная ориентировка выполнялась точнее и занимала гораздо меньше времени, чем в группе сравнения. Заднебоковой хирургический доступ к приводящей к свищу тощекишечной петле снизил риск ее повреждения, так как отпала необходимость протяженного энтеролиза. Поэтому у больных основной группы наблюдения послеоперационный период протекал легче и с меньшим количеством осложнений, чем в группе сравнения.Заключение. Заднебоковой доступ предотвратил необходимость протяженного висцеролиза и позволил надежно и атравматично выполнить межкишечный анастомоз, отключающий свищ. Одностороннее отключение тощекишечного свища в периоде послеоперационного пареза кишечника обеспечило разгрузку межкишечного анастомоза, подобно дефинитивной еюностоме Майдля. Приведенные положительные стороны предложенного оперативного вмешательства обусловили достоверное снижение послеоперационных осложнений и летальности по сравнению с результатами известных хирургических операций того же назначения