Radiation back-reaction in relativistically strong and QED-strong laser fields

The emission from an electron in the field of a relativistically strong laser pulse is analyzed. At the pulse intensities of \ge 10^{22} W/cm^2 the emission from counter-propagating electrons is modified by the effects of Quantum ElectroDynamics (QED), as long as the electron energy is sufficiently high: E \ge 1 GeV. The radiation force experienced by an electron is for the first time derived from the QED principles and its applicability range is extended towards the QED-strong fields.Comment: 4 pages, 4 figure

Emission and its back-reaction accompanying electron motion in relativistically strong and QED-strong pulsed laser fields

The emission from an electron in the field of a relativistically strong laser pulse is analyzed. At pulse intensities of J > 2 10^22 W/cm2 the emission from counter-propagating electrons is modified by the effects of Quantum ElectroDynamics (QED), as long as the electron energy is sufficiently high: E > 1 GeV. The radiation force experienced by an electron is for the first time derived from the QED principles and its applicability range is extended towards the QED-strong fields.Comment: 14 pages, 5 figures. Submitted to Phys.Rev.

Increasing the production efficiency of chrysotile cement products

Improving the efficiency of chrysotile-cement products is achieved by changing the raw materials with additives, changing their structure and properties, generating new kinds of chrysotile-cement productsnoBelgorod State Universit

Relativistic attosecond physics

A study, with particle-in-cell simulations, of relativistic nonlinear optics in the regime of tight focus and ultrashort pulse duration (the λ3λ3 regime) reveals that synchronized attosecond electromagnetic pulses [N. M. Naumova, J. A. Nees, I. V. Sokolov, B. Hou, and G. A. Mourou, Phys. Rev. Lett. 92, 063902 (2004)] and attosecond electron bunches [N. Naumova, I. Sokolov, J. Nees, A. Maksimchuk, V. Yanovsky, and G. Mourou, Phys. Rev. Lett. 93, 195003 (2004)] emerge efficiently from laser interaction with overdense plasmas. The λ3λ3 concept enables a more basic understanding and a more practical implementation of these phenomena because it provides spatial and temporal isolation. The synchronous generation of strong attosecond electromagnetic pulses and dense attosecond electron bunches provides a basis for relativistic attosecond optoelectronics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87762/2/056707_1.pd

Strea MRAK a streaming multi-resolution adaptive kernel algorithm

Kernel ridge regression (KRR) is a popular scheme for non-linear non-parametric learning. However, existing implementations of KRR require that all the data is stored in the main memory, which severely limits the use of KRR in contexts where data size far exceeds the memory size. Such applications are increasingly common in data mining, bioinformatics, and control. A powerful paradigm for computing on data sets that are too large for memory is the streaming model of computation, where we process one data sample at a time, discarding each sample before moving on to the next one. In this paper, we propose StreaMRAK - a streaming version of KRR. StreaMRAK improves on existing KRR schemes by dividing the problem into several levels of resolution, which allows continual refinement to the predictions. The algorithm reduces the memory requirement by continuously and efficiently integrating new samples into the training model. With a novel sub-sampling scheme, StreaMRAK reduces memory and computational complexities by creating a sketch of the original data, where the sub-sampling density is adapted to the bandwidth of the kernel and the local dimensionality of the data. We present a showcase study on two synthetic problems and the prediction of the trajectory of a double pendulum. The results show that the proposed algorithm is fast and accurate

Algorithmic presentation of the independent work of the students of the vocational pedagogical university in the conditions of the synchronous pedagogical control

The topicality of the investigated problem is stipulated by the demand for specialists able to develop algorithmic preparedness to perform professional activities, the level of which corresponds to modern level of technological production. The purpose of the article is to diagnose the influence of the synchronous pedagogical control on the development of preparedness for the algorithmic presentation of the independent work of the students of professional and pedagogical university. The leading approach to the study of this problem is the method of algorithmic presentation of the synchronous pedagogical control of the process of assimilation by the students of the professional knowledge and skills, enabling them to develop in algorithmic preparedness corresponding to the level of complexity of the implemented educational and professional activities. The article deals with the psychological and pedagogical approaches in the study of algorithmic preparedness to work independently as well as with the arrangements for the synchronous type of the pedagogical control in the discipline of profile preparation of students of the Russian State Vocational Pedagogical University and with the results achieved during experimental search of work indicating the effectiveness and efficiency of this type of control. The materials of the article may be useful to teachers of vocational training in the organization of practical training in the disciplines of profile preparation containing procedural knowledge and skills and, consequently, an algorithmic nature. © 2016 Dneprov et al

The Impact of Global Challenges on the Functioning of Labor Market

At any stage of the country’s socio-economic development, labor market is the most sensitive indicator of changing market conditions, a rapid response to the manifestations of macro-economic instability and turbulence of economy. Therefore, one of the priorities of the State policy in the sphere of employment of the population is the analysis and forecasting the status of labor market in the period of significant shifts in its established tendencies related to the rapid pace of globalization of the worldwide economy. The article is aimed at analyzing the impact of global challenges and the related risks on both the world and the national labor markets, defining the appropriate directions of the State policy and economic conditions for its effective functioning during the period of macro-economic instability. The topical global challenges influencing the current functioning and trajectories of development of both the worldwide and the national labor markets are systematized. The list of risks faced by the Ukrainian economy is provided. The directions of the State policy together with conditions for efficient adaptation of the population and economy of Ukraine in the period of macro-economic instability connected with the newest problems of mankind are formulated. The technologies, professions and skills that be most in demand in the future and be able to radically change the appearance of the world business in the coming years, are indicated and their advantages and the related problems are considered

Role of demyelination in the persistence of neurological and mental impairments after COVID-19

Long-term neurological and mental complications of COVID-19, the so-called post-COVID syndrome or long COVID, affect the quality of life. The most persistent manifestations of long COVID include fatigue, anosmia/hyposmia, insomnia, depression/anxiety, and memory/attention deficits. The physiological basis of neurological and psychiatric disorders is still poorly understood. This review summarizes the current knowledge of neurological sequelae in post-COVID patients and discusses brain demyelination as a possible mechanism of these complications with a focus on neuroimaging findings. Numerous reviews, experimental and theoretical studies consider brain demyelination as one of the mechanisms of the central neural system impairment. Several factors might cause demyelination, such as inflammation, direct effect of the virus on oligodendrocytes, and cerebrovascular disorders, inducing myelin damage. There is a contradiction between the solid fundamental basis underlying demyelination as the mechanism of the neurological injuries and relatively little published clinical evidence related to demyelination in COVID-19 patients. The reason for this probably lies in the fact that most clinical studies used conventional MRI techniques, which can detect only large, clearly visible demyelinating lesions. A very limited number of studies use specific methods for myelin quantification detected changes in the white matter tracts 3 and 10 months after the acute phase of COVID-19. Future research applying quantitative MRI assessment of myelin in combination with neurological and psychological studies will help in understanding the mechanisms of post-COVID complications associated with demyelinatio