58 research outputs found

    Submonolayer growth with decorated island edges

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    We study the dynamics of island nucleation in the presence of adsorbates using kinetic Monte Carlo simulations of a two-species growth model. Adatoms (A-atoms) and impurities (B-atoms) are codeposited, diffuse and aggregate subject to attractive AA- and AB-interactions. Activated exchange of adatoms with impurities is identified as the key process to maintain decoration of island edges by impurities during growth. While the presence of impurities strongly increases the island density, a change in the scaling of island density with flux, predicted by a rate equation theory for attachment-limited growth [D. Kandel, Phys. Rev. Lett. 78, 499 (1997)], is not observed. We argue that, within the present model, even completely covered island edges do not provide efficient barriers to attachment.Comment: 7 pages, 2 postscript figure

    Deformaciones isométricas infinitesimales de superficies multidimensionales ensambladas

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    The article introduces the concept of multidimensional pasted surfaces and considers the case of different dimensions in the surfaces to be pasted. Infinitesimal deformations of such surfaces are also considered. In a general way, it is proved that, if the surface pieces have first order infinitesimal rigidity, then the pasted surface contains infinitesimal rigidity of first order.Se introduce el concepto de superficies multidimensionales ensambladas y no se descarta el caso cuando los trozos de las superficies a ensamblar tienen diferentes dimensiones. Se consideran deformaciones infintesimales de estas superficies. En forma muy general, se demuestra que si los trozos de superficies contienen rigidez infinitesimal de primer grado, entonces la superficie ensamblada contiene rigidez infitesimal de primer grado

    Development of Social institution of Mass media in Information Society and Legal Field of the Personal and Corporative Information Security

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    The crucial role of information in the post-industrial society leads to the necessity and actuality of social sciences’ studying mass communication channels. Sociological analysis of mechanisms and tools of the information and knowledge’ creation and transmission, as well as channels of open access to data and competences, raises questions on the new opportunities, but also on the social constraints for the functioning of mass communication systems. As part of this perspective, the proposed material focuses on the problems of the evolution and dynamics of security issues from the point of view of social-legal assessment of the functioning of the Institute of Mass Communication in the Information Society. The submission is built in the inferential deductive logic, from the general analysis of the information society and the studies of institutionalizing communicative channels and regulatory mechanisms that establish restrictions, crucial for individual and community’ protection, towards the implementation of the private information security of individuals and corporate actors. Analysis of regulators of the behavior in the postmodern socio-cultural environment at the level of micro-sociological empirical research is carried out in terms of legal protection of honor and dignity of individuals and of corporate identity. The theoretical and practical analysis concludes on the need to formalize and differentiation of types of legal regulatory models. By identifying the specific features of the information society, revealing the elements of the traditional society, the study concerns the dynamics of the role of information as a resource and as a form of existence of the actor in the space of an information society. In view of the interpretation of information security as a society’s ability to minimize the obstacles to the free realization and actualization of socially acceptable interests of individuals and groups, the material deals with a theoretical question of protection of data, and with theoretical and practical sociological and legal purposes of the protection against abuse and violation of the integrity and credibility

    Combination of Mucocele of the Appendix and Chronic Calculous Cholecystitis: Case Report

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    Background: The analysis of the data presented in the foreign and national literature shows that a combination of the appendix mucocele and calculous cholecystitis is extremely rare, and the implementation of simultaneous surgical treatment in the laparoscopic version is the optimal approach. Clinical case description. Here, we present a clinical case of chronic calculous cholecystitis in combination with mucocele of the appendix in an 84-year-old patient. The main complaint was pulling pain in the right iliac region. The diagnosis was made on the basis of the main and additional methods of examination: clinical picture, ultrasound, multispiral computed tomography and magnetic resonance imaging of the abdominal organs. In a planned manner, a simultaneous surgical intervention was performed consisting of laparoscopic appendectomy and cholecystectomy. The operation duration was 1 hour 15 minutes. The morphological examination confirmed the diagnosis of calculous cholecystitis and mucocele of the appendix. The patient was discharged in a satisfactory condition on the 4th day. Conclusion. This clinical case shows that the dynamic observation of mucocele of the appendix, even in elderly patients with a comorbid pathology, is unjustified. A simultaneous surgical intervention in the form of laparoscopic appendectomy and cholecystectomy treats the two nosologies and prevents repeated hospitalization and surgery

    Особенности решения уравнений метода обратной задачи для синтеза устойчивого управляемого движения шагающих роботов

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    Рассматривается задача синтеза управляемого движения шагающих роботов методом обратной задачи. Уравнения метода обратной задачи представляются с помощью методов динамики связанных систем тел, как уравнения движения свободных тел и уравнения связей. Введены различные группы уравнений связей — для задания походки робота, для выполнения условий устойчивости робота и для согласованного движения заданных звеньев робота. Ключевая особенность уравнений метода обратной задачи в такой постановке состоит в наличии вторых производных координат системы в уравнениях связей, обеспечивающих поддержание роботом вертикального положения. Однозначное решение таких уравнений в общем случае невозможно из-за неопределенности начальных условий для множителей Лагранжа. Рассмотрен приближенный метод решения обратной задачи без учета инерционных составляющих в уравнениях связей, определяющих устойчивость робота. Выписаны уравнения связей, которые определяют согласованное движение отдельных звеньев робота и необходимые для однозначного решения задачи на основе приближенных уравнений. Представлена реализация методов синтеза программного движения в системе управления робота андроида АР600. Выполнено сравнение теоретических и экспериментальных показателей управляемого движения. Установлено, что при достигнутой высокой точности управления следящими приводами относительными движениями звеньев робота с погрешностью несколько процентов, показатели абсолютных движений робота, в частности, углы крена, рыскания и тангажа, отличаются от программных на 30-40%. Показано, что предложенный метод позволяет синтезировать управление роботом в квазистатическом режиме для различных типов движений — вперед, вбок, движение по ступенькам, наклоны и так далее

    Drainage methods in patients with unformed intestinal fistulas during the preparation to the surgical treatment

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    The aim of the study is to analyze the data of the modern foreign and domestic literature on intestinal fistulas, including high unformed small intestinal fistulas, their classification, treatment methods, drainage methods, their types and effectiveness. Research method: the search in the elibrary, CyberLeninka, PubMed and SpringerLink databases. Intestinal fistulas, often found in the surgical practice, appear due to a number of reasons (errors in the surgical technique and conservative treatment, tactical errors, the presence of severe concomitant diseases, etc.) and present a high-risk factor for death. Clinically, intestinal fistulas can differ depending on their localization, etiology, morphology, function, complications, etc., that causes certain difficulties in choosing the treatment method and reduces its success. Special attention is paid to high unformed small intestinal fistulas, which are accompanied by pronounced impairment of the body's homeostasis system, on the one hand, and the need for a multi-stage treatment, on the other hand. The treatment regimen for high unformed small intestinal fistulas includes both conservative and surgical approaches. The conservative method of treatment includes an intensive infusion therapy, control of the source of infectious complications, reduction of irretrievable losses, nutritional therapy, and a local treatment, which consists in protecting the tissues from the aggressive intestinal content and various methods of adequate drainage of the wound. The drainage methods used for intestinal fistulas differ depending on the principle of their operation, the surgical drain material, the configuration of the wound, the fistula morphology, the number of fistulas, etc. Active and vacuum methods seem to be used most frequently and efficiently in the local treatment of high unformed small intestinal fistulas. So far, according to the (very limited) modern literature, there has been a diversity in the effectiveness of the drainage treatment approaches in patients with high unformed small intestinal fistulas, thus, further studies are needed to study and evaluate their pathogenetic role and effectiveness

    Total hip revision in patients with isolated aseptic loosening of the acetabular component

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    Introduction Aseptic loosening of the acetabular component is one of the most common late complications of total hip arthroplasty. Current principles of its treatment consist in replacement of the loosened cup and of the head-and-liner friction couple. There is no unified opinion regarding the stem if it is stable and well-aligned. Methods We have analyzed examination and treatment results of 16 patients with isolated aseptic loosening of the acetabular component that underwent total revision. The results of treatment were assessed using the Harris Hip Score and Oxford Hip Score questionnaires on the 10th postoperative day, and then at follow-ups after three, six and 12 months. Results The average duration of the operation was 132.5 [115; 150] minutes. Intraoperative blood loss ranged from 600 to 2500 ml and averaged 900 ml [750; 1450]. Analysis of hematological parameters (RBC, HGB, HCT) showed moderate anemia in 14 patients (87.5 %) and only two patients (12.5 %) had mild anemia on the 10th postoperative day. The mean volume of erythrocyte mass transfusion was 450 ml [300; 775]. The final results of treatment were assessed as fair with Harris Hip Score after 12 months. The Oxford Hip Score results of treatment were in the range from 30 to 39 points after 12 months that confirmed the need for additional conservative measures for hip joint stability. Conclusion Surgical treatment of isolated aseptic loosening of the acetabular component requires differentiated tactical solutions for defining the scope of hip revision

    IMMERSIONS OF METRICS INTO FLAT SPACES AND DEFORMATIONS OF IMMERSIONS

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    The theory of the general analytical and infinite-small immersion deformations has been developed, the classes of the Riemannian and pseudo-Riemannian metrics immersed smoothly into the Euclidean and pseudo-Euclidean spaces with low codimensionality has been developed. The results can be used in the theory of isometric immersions and different theories of the deformations.Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

    Deformaciones isométricas infinitesimales de superficies multidimensionales ensambladas

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    The article introduces the concept of multidimensional pasted surfaces and considers the case of different dimensions in the surfaces to be pasted. Infinitesimal deformations of such surfaces are also considered. In a general way, it is proved that, if the surface pieces have first order infinitesimal rigidity, then the pasted surface contains infinitesimal rigidity of first order.Se introduce el concepto de superficies multidimensionales ensambladas y no se descarta el caso cuando los trozos de las superficies a ensamblar tienen diferentes dimensiones. Se consideran deformaciones infintesimales de estas superficies. En forma muy general, se demuestra que si los trozos de superficies contienen rigidez infinitesimal de primer grado, entonces la superficie ensamblada contiene rigidez infitesimal de primer grado

    Numerical Simulation Using Finite-Difference Schemes with Continuous Symmetries for Processes of Gas Flow in Porous Media

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    This article presents the applications of continuous symmetry groups to the computational fluid dynamics simulation of gas flow in porous media. The family of equations for one-phase flow in porous media, such as equations of gas flow with the Klinkenberg effect, is considered. This consideration has been made in terms of difference scheme constructions with the preservation of continuous symmetries, which are presented in original parabolic differential equations. A new method of numerical solution generation using continuous symmetry groups has been developed for the equation of gas flow in porous media. Four classes of invariant difference schemes have been found by using known group classifications of parabolic differential equations with partial derivatives. Invariance of necessary conditions for stability has been shown for the difference schemes from the presented classes. Comparison with the classical approach for seeking numerical solutions for a particular case from the presented classes has shown that the calculation speed is greater by several orders than for the classical approach. Analysis of the accuracy for the presented method of numerical solution generation on the basis of continuous symmetries shows that the accuracy of generated numerical solutions depends on the accuracy of initial solutions for generations
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