898 research outputs found
Electron mobility on a surface of dielectric media: influence of surface level atoms
We calculate the contribution to the electron scattering rate from the
surface level atoms (SLA), proposed in [A.M. Dyugaev, P.D. Grigoriev, JETP
Lett. 78, 466 (2003)]. The inclusion of these states into account was
sufficient to explain the long-standing puzzles in the temperature dependence
of the surface tension of both He isotopes and to reach a very good agreement
between theory and experiment. We calculate the contribution from these SLA to
the surface electron scattering rate and explain some features in the
temperature dependence of the surface electron mobility. This contribution is
essential at low temperature when the He vapor concentration is
exponentially small. For an accurate calculation of the electron mobility one
also needs to consider the influence of the clamping electric field on the
surface electron wave function and the temperature dependence of the He3
chemical potential.Comment: 6 pages, 1 figur
Analysis of migration processes based on census data
The subject matter of research is the internal migration processes of the Russian population in the period from the 1960s to 2010. The research is based on the data about the territorial population flows published in the all-Union census materials of 1970, 1979, and 1989, and in the all-Russia census materials of 2002 and 2010. The basic migration flows and directions are considered. Methodologically, the analysis of migration is based on the use of end-to-end indicators enabling to assess the dynamics of migration processes over a long period. Special attention is paid to rural-urban internal migrations, the volumes, patterns and consequences of which have not been so far properly investigated or assessed. The authors offer and calculate relative indicators that have never been used to assess the processes in question. To make the census materials of the soviet and post-soviet periods comparable, the economic zoning adopted before 2000 is used, and the administrative-territorial network is unified. The authors confirm the hypothesis that from decade to decade the intensity of territorial mobility of both urban and rural population was reduced. Interregional migration flows are considered, and various tendencies and migration intensity for over four decades are de ned. The authors analyze the dynamics in the structure of migrants by the time they lived in the place of their permanent residence in various regions. The research shows that the tendencies developed at that time and persisting continue to adversely affect the territorial re-distribution of population and the regional social and economic development of the country. The research results can be used in adjusting the regional socio-economic and migration policy.The article has been prepared with the support of the Russian Humanitarian Science Foundation Project № 14–02–00525
Sentinel headache as a warning symptom of ischemic stroke
Background: There are no previous controlled studies of sentinel headache in ischemic stroke. The purpose of the present study was to evaluate the presence of such headache, its characteristics and possible risk factors as compared to a simultaneous control group. Methods: Eligible patients (n = 550) had first-ever acute ischemic stroke with presence of new infarction on magnetic resonance imaging with diffusion-weighted imaging (n = 469) or on computed tomography (n = 81). As a control group we studied in parallel patients (n = 192) who were admitted to the emergency room without acute neurological deficits or serious neurological or somatic disorders. Consecutive patients with stroke and a simultaneous control group were extensively interviewed soon after admission using validated neurologist conducted semi-structured interview forms. Based on our previous study of sentinel headache in transient ischemic attacks we defined sentinel headache as a new type of headache or a previous kind of headache with altered characteristics (severe intensity, increased frequency, absence of effect of drugs) within seven days before stroke. Results: Among 550 patients with stroke 94 patients (17.1%) had headache during seven days before stroke and 12 (6.2%) controls (p < 0.001; OR 3.9; 95% CI 1.7-5.8). Totally 81 patients (14.7%) had sentinel headache within the last week before stroke and one control. Attacks of arrythmia during seven days before stroke were significantly associated with sentinel headache (p = 0.04, OR 2.3; 95% CI 1.1-4.8). Conclusions: A new type of headache and a previous kind of headache with altered characteristics during one week before stroke are significantly more prevalent than in controls. These headaches represent sentinel headaches. Sudden onset of such headaches should alarm about stroke. © 2020 The Author(s)
Typology of strategies of personality meaning-making during professional education
The importance of the studied issue is conditioned by the fact that high dynamic of processes in the labour market requires constant work of an individual on self-determination and search for significance of his/her professional activity. The purpose of research is theoretical development and empirical verification of the types of strategies of meaning-making based on perceptions of future in terms of professional self-determination of the personality at the stage of vocational training. Basic research methods: modelling, psychosemantic approach, allowing to perform research process with the possibility of more in-depth analysis of the results. Research results: the model of the semantical future in the consciousness of the personality, which includes affective, cognitive, activity and intentional components is developed and empirically verified; the types of strategies of meaning-making based on perceptions of future in terms of professional selfdetermination of the personality at the stage of vocational training is identified, the typology includes the following 3 types of the meaning-making strategies: strategy of integration of the meaning of education and profession in the model of own future, strategy of disintegration and strategy of uncertainty and delay of the semantical choice. Significance of results: analysis of the semantical grounds for future professional activity will help optimize the training of a competent, competitive and adaptive specialist ready to continuous self-development, and to intensify the process of professional self-determination and building life and professional prospects of the personality at the stage of vocational training, as exactly at this stage the professional competence and identity is built up. © 2016 Shchipanova et al
Hydrolysate of ovalbumin: production and evaluation of the functional properties of peptides
Chicken eggs proteins and their derivatives, like protein hydrolysates, peptides and amino acids, possess high nutritional value and provide a wide range of biological activity. They serve as sources for development of functional ingredients that draw the attention of specialists in the food production and biomedical industries, as well as the livestock feed industry. Enzymatic hydrolysis of proteins is a popular process for obtaining bioactive peptides with multifunctional properties. The purpose of this study is to obtain a hydrolysate of ovalbumin with a high degree of hydrolysis and to determine its functional and technological parameters. The research presents a two-stage scheme of ovalbumin hydrolysis with the help of pepsin and trypsin which provide high degree of hydrolysis (82–83%). The fractional composition of the hydrolysate is determined. The fractional composition is represented by three main fractions (high, medium and low molecular weight). The summarized antioxidant activity (SAA) of the hydrolysate is considered within the dynamics of the hydrolysis process. The highest SAA value was noted after 2 hours, and it amounted to 170.23 mg/l; at the end of hydrolysis the SAA value was equal to 114.31 mg/l. When analyzing the SAA, it was found that the main contribution to the summarized antioxidant activity of the ovalbumin hydrolysate is made by peptides of the medium molecular fraction. The microfiltration process, used in the research, made it possible to separate high-molecular compounds, which led to an increase in the SAA of the hydrolysate to 189.9 mg/l. The main functional and technological parameters of the hydrolysate are determined in this research. The comprehensive study of the biological activity and functional characteristics of egg protein hydrolysates and their peptides provides a theoretical basis for expanding the range of functional ingredients obtained from food proteins and for replenishing the range of functional foods.Chicken eggs proteins and their derivatives, like protein hydrolysates, peptides and amino acids, possess high nutritional value and provide a wide range of biological activity. They serve as sources for development of functional ingredients that draw the attention of specialists in the food production and biomedical industries, as well as the livestock feed industry. Enzymatic hydrolysis of proteins is a popular process for obtaining bioactive peptides with multifunctional properties. The purpose of this study is to obtain a hydrolysate of ovalbumin with a high degree of hydrolysis and to determine its functional and technological parameters. The research presents a two-stage scheme of ovalbumin hydrolysis with the help of pepsin and trypsin which provide high degree of hydrolysis (82–83%). The fractional composition of the hydrolysate is determined. The fractional composition is represented by three main fractions (high, medium and low molecular weight). The summarized antioxidant activity (SAA) of the hydrolysate is considered within the dynamics of the hydrolysis process. The highest SAA value was noted after 2 hours, and it amounted to 170.23 mg/l; at the end of hydrolysis the SAA value was equal to 114.31 mg/l. When analyzing the SAA, it was found that the main contribution to the summarized antioxidant activity of the ovalbumin hydrolysate is made by peptides of the medium molecular fraction. The microfiltration process, used in the research, made it possible to separate high-molecular compounds, which led to an increase in the SAA of the hydrolysate to 189.9 mg/l. The main functional and technological parameters of the hydrolysate are determined in this research. The comprehensive study of the biological activity and functional characteristics of egg protein hydrolysates and their peptides provides a theoretical basis for expanding the range of functional ingredients obtained from food proteins and for replenishing the range of functional foods
Time management and professional identity of students of pedagogical universities
Topicality of the problem under research is stipulated by the necessity of personal characteristics consideration in the process of organization of educational and vocational activities of the future teachers in the conditions of educational medium, which sets high requirements to the students' time competence. The aim of the article is to study the influence of time management peculiarities on the components of students' professional identity. The primary research method applied was psychodiagnostic testing with further statistical data processing, enabling quantitative assessment of formedness of time competence and professional identity in students of a pedagogical university, as well as establishing the interaction character of the phenomena of interest. Research results: in the article peculiarities of students time management within different stages of professional identity are presented, and the interconnection between time competence and professional identity components is considered. Based on empirical data, there can be drawn a conclusion that time competence development will facilitate formation of professional identity for the future professionals. Received results can find practical implementation in development of programs for psychological follow-up of professional formation of student's identity in the system of university education. © 2016 Lebedeva et al
Unstable Hemostasis and Specific Postoperative Complications (Literature Review)
Perioperative bleeding occupies a leading place among all surgical complications and, despite the rapid development of surgery, remains relevant to this day. In addition to an increase in mortality, bleeding can cause the development of other postoperative complications, which lead to disability of patients and to a decrease in the quality of life in all age groups. Most perioperative bleeding are caused by technical errors. This article reviews the problem of perioperative bleeding from the point of view of impaired coagulation capabilities of the body. The main etiopathogenetic features of hemostasis during the development of this complication are considered. The analysis of postoperative complications, which were directly or indirectly caused by bleeding during or after surgery, is presented. The prevalence of these complications in various areas of surgery has been demonstrated. More detailed study of the hemostasis system and the identification of predictors of hemostasis difficulties before the surgery may cause an improvement in the results of surgical treatment and reduce the number of postoperative complications and the duration of hospital stay. Accordingly, this will lead to a decrease in the cost of treatment and an increase in patient satisfaction with the medical care. In connection with the above, there is a great interest among surgeons and anesthesiologists in preventing the development of perioperative bleeding
Professional Identity and Trans-Perspective of Professional Development of Future Teachers
The article presents a theoretical analysis of the problem of formation of professional identity in conditions of uncertainty and increasing multidimensionality of professional and educational space. The attention is focused on the fact that the dynamics of social processes is expressed in changing the requirements for the content and quality of work, the complexity of professional training. The multifactorial nature of professional development leads to the complication of the strategy of building a professional trans-perspective and requires a specially organized acmeological support of the identification process at the stage of vocational education. Within the theoretical review the definition of professional identity with the description of its structure is given, the author’s definition of professional trans-perspective is proposed. An important part of the article is the results of an empirical study of the features of professional identity and professional trans-perspective of students who are future teachers of vocational training. The interrelation of the main characteristics of professional trans-perspective - length, event density with indicators of professional identity: maturity, formation, activity of professional position, educational and professional plans - is revealed. Thus, the characteristics of professional identity can be considered as predictors for predicting a person’s professional future. In the final part, it is proposed to intensify the work on the development of professional identity of second-year students by supplementing the curriculum with elective modules aimed at the deficit aspects of professional self-determination
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