Двойная периодичность механических свойств тонкого ледяного поля, сформированного в условиях бокового стеснения

Experimental data and results of theoretical modeling of the bending of a viscoelastic floating ice plate formed under constrained deformation are analyzed. When a thin plate of ice is frozen on the water surface under conditions of constrained deformation, which may be caused, for example, by the rigid walls of the pool, periodic changes in physical properties occur in it, in particular, periodic penetration resistance. Experimental results confirming this fact were obtained during tests of a thin ice cover at the Krylov State Research Center (Saint-Petersburg, Russia). A characteristic feature of the test results is that their spatial distributions can be represented with sufficient accuracy as an overlap of two periodic functions with significantly different periods: long-wave and short-wave components. In this paper, a detailed analysis of experimental data is given, which makes it possible to isolate these components. Furthermore, the theoretical model that explains the physical causes for double periodicity is proposed. The model assumes viscoelastic quasi-static deformation of the ice plate caused by small fluctuations of the water level in the basin and random disturbances of its surface. An analytical solution for the model case of cylindrical bending is derived. The solution is presented in the form of an expansion in terms of eigenfunctions of differential operators generated by the boundary value problem under study. It has been established that when a thin plate of ice freezes under conditions of constrained deformation, there are at least two reasons for the appearance of a periodic structure: a general loss of stability as an elastic structure and a local loss of stability by a viscoelastic-plastic mechanism. The results obtained can be used in the development of the theory of ice compression, in assessing the causes of variation in the local strength of ice fields and the possibility of their artificial destruction.Обсуждаются двойная периодичность (cжатие в плоскости ледяного поля и реологический характер локализации и накопления изгибных деформаций в нём), методы её экспериментальной идентификации, математическое моделирование и причины появления. Установлены две причины возникновения периодичности: общая потеря устойчивости упругой конструкции и локальная неустойчивость по вязкоупругому механизму. Первая зависит от геометрии пластины в целом и условий её закрепления, вторая - от толщины, усилия обжатия и физико-механических свойств льда

ПНЕВМОНИЯ У ЛИЦ С НАРКОТИЧЕСКОЙ ЗАВИСИМОСТЬЮ

The objective of this study was to investigate clinical course of septic pneumonia in patients with intravenous drug dependence.Methods. Routine clinical and radiological examination has been conducted in 55 consecutive pneumonia patients with intravenous narcotic dependence hospitalized in two hospitals at Barnaul city. A comparator group included 19 patients with septic pneumonia without drug abuse.Results. The majority of patients with intravenous drug dependence were younger than 40 years old (p < 0.001), 42 (76.4 %) were men. HIV infection was detected in 20 patients (36.4 %). Opioid abuse was found in 11 patients, heroin abuse in 16 and desomorphine abuse in 28 patients; 51 patients were diagnosed with viral hepatitis (B, C, or both). In 61.8 % of patients with intravenous drug dependence, severity of pneumonia by CURB-65 score was ³ 3 compared to 2 in 68.4 % of comparative patients (c2 = 5.20, p = 0.044). The average SOFA score was 6.2 ± 1.8. The APACHE II score was > 25 in 29 patients (52.7 %). Severe sepsis (ACC / SCCM, 1992) more often diagnosed in patients with intravenous drug dependence (n = 31; c2 = 5.10, p = 0.046). In the comparator group, sepsis was diagnosed in 11 patients (c2 = 3.19; p = 0.129). Septic shock was developed in 5 and 3 patients, respectively.Conclusion. In patients with intravenous drug dependence, pneumonia has more severe course with more frequent complications including tricuspid valve infective endocarditis, hepatic injury, bilateral and destructive lung lesions. Apart from adequate antimicrobial therapy, treatment of such patients should be targeted to improvement in microcirculation disorders

The Efficiency of National Innovation Systems in Post-Soviet Countries: DEA-Based Approach

The efficiency of the national innovation system (NIS) is widely considered to be the most important factor of innovation-based economic growth. Using the wide spectrum of different metrics for measuring the efficiency of NIS, modern studies focus mainly on high-income or upper-middle-income countries, while the effectiveness of the NIS in post-Soviet countries has not been studied enough. The post-socialist transformation has led to different models of economic development in these countries, which can be divided into three groups: a group with developed European institutions, a group with a focus on the European path of development, and, finally, a group of countries with an economic model of “state capitalism”. These models formed the trajectory of innovative development. The main purpose of this study is to compare the performance of NIS in post-Soviet countries and to find out whether differences between development institutions can help explain differences in the performance of NIS. The study applies the DEA methodology and considers NISs as homogeneous economic agents, which transform the same types of inputs (knowledge gained using human and financial resources) into the same types of positive outcomes (innovative products and services). The results of a study conducted on data for the period 2011–2018 show that there is no evidence to support the hypothesis that EU institutions or the type of economic model of the country directly relate to the effectiveness of the NIS. The example of Kazakhstan shows that NIS can be effective, even with strong state intervention in the economy. Taken together, the results of the paper suggest that the structure of R&D expenditures by sources of funding and types of research plays an important role in the formation of effective NIS