Theory of 4e versus 2e supercurrent in frustrated Josepshon-junction rhombi chain

We consider a chain of Josepshon-junction rhombi (proposed originally in \cite{Doucot}) in quantum regime, and in the realistic case when charging effects are determined by junction capacitances. In the maximally frustrated case when magnetic flux through each rhombi $\Phi_r$ is equal to one half of superconductive flux quantum $\Phi_0$, Josepshon current is due to correlated transport of {\em pairs of Cooper pairs}, i.e. charge is quantized in units of $4e$. Sufficiently strong deviation $\delta\Phi \equiv |\Phi_r-\Phi_0/2| > \delta\Phi^c$ from the maximally frustrated point brings the system back to usual $2e$-quantized supercurrent. We present detailed analysis of Josepshon current in the fluctuation-dominated regime (sufficiently long chains) as function of the chain length, $E_J/E_C$ ratio and flux deviation $\delta\Phi$. We provide estimates for the set of parameters optimized for the observation of $4e$-supercurrent.Comment: 23 pages, 9 figure

Ways of prevention of funding for youth informal groups of extremist orientation

The relevance of the article. The article explores ways of financing youth informal groups (associations) of the extremist. It is proposed to divide all youth informal groups (associations) that commit crimes of extremist nature into two types: 1) formed by its leader(s); 2) acting as the youth part of international extremist organizations, radical movements, and political parties. The process of financing an extremist association depends on how it was created. The methodology of the research. The scientific literature on youth informal groups (associations), the fight against extremism, the investigation of group crimes, etc. have been analyzed for writing the article. Besides, theoretical methods such as analysis method, synthesis method, comparison method, and classification method were used during the study. An empirical basis for the study was the investigation of crimes committed by members of youth informal groups (associations) of extremist orientation. Research results. In conclusions, the authors emphasize that identifying sources of funding is an essential condition for the process of the detection and investigation of crimes committed by members of extremist youth groups (unions). Identifying sources of funding and overlapping funding channels for youth extremist associations is a promising area of applied research

Interrogation of the victims during the investigation of crimes committed by youth extremist groups

For several years in Ukraine and in other countries, the activity of informal criminal groups, in particular, of the youth groups, can be observed. Thus, there is a need for theoretical understanding of the activities of the respective criminal groups in order to make proposals for improving the current criminal procedural legislation. The article emphasizes the importance of evidential information that can be obtained during the interrogation of victims of crimes committed by youth informal groups of extremist orientation. In this connection, the authors have considered: 1) the features of the victims to be taken into account when investigating the criminal activity of informal youth extremist groups; 2) sources of information on the identification of victims of crimes committed by members of youth informal groups of extremist orientation; 3) separate questions of questioning of the specified category of victims. The scientific literature devoted to informal youth groups, fight against extremism, investigation of group crimes, etc. was analyzed during the scientific research. In addition, such scientific methods as observation, analysis, synthesis, comparison, generalization, extrapolation were used. The empirical basis for the study was the investigation of crimes committed by members of youth informal groups (in particular, with extremist orientation). A promising area of scientific and applied research of the stated problem is the development of methodological recommendations on the conduct of communicative investigative (search) actions, in particular, the questioning of such a procedural figure as the victim

Investigation of Crimes Committed By Members of Youth Informal Groups

The deterioration of the criminal situation in Ukraine makes it necessary to intensify the work of law enforcement agencies to combat crime. In particular, there is a need to improve the investigation methods of certain types of crimes. This category of crimes includes crimes committed by members of youth informal groups.The object of the study was public relations in the field of investigation of crimes committed by members of youth informal groups. As a result of the study, the features of proposing a version of the involvement of members of a youth informal group in criminal activity are considered. Initial investigative (search) actions are determined, which serve as the basis for verifying the indicated version. When working on the article, special literature was analyzed devoted to the study of various aspects of the activities of youth informal groups, criminal associations, the fight against crime, the investigation of group crimes, etc.In addition, such scientific methods as observation, analysis, synthesis, and generalization were used. The authors used a combination of methods of scientific knowledge, which together allowed them to achieve the stated results of the study. Among other, the methods of analysis, synthesis, extrapolation, generalization method were used.The empirical basis of the study was the materials of the investigation of crimes committed by members of youth informal groups and associations

Quantum and Thermal Depinning of a String from a Linear Defect

The problem of a massive elastic string depinning from a linear defect under the action of a small driving force is considered. To exponential accuracy the decay rate is calculated with the help of the instanton method; then, fluctuations of the quasiclassical solution are taken into account to determine the preexponential factor. The decay rate exhibits a kind of first order transition from quantum tunneling to thermal activation with vanishing crossover region. The model may be applied to describe nucleation in 2-dimensional first order quantum phase transitions.Comment: Revtex. 11 pages + 4 PS figures. Accepted for publication in PR

Electrostatics of Vortices in Type II Superconductors

In a type II superconductor the gap variation in the core of a vortex line induces a local charge modulation. Accounting for metallic screening, we determine the line charge of individual vortices and calculate the electric field distribution in the half space above a field penetrated superconductor. The resulting field is that of an atomic size dipole ${\bf d} \sim e a_{{\rm B}} {\bf {\hat z}}$, $a_{{\rm B}} = \hbar^2/m e^2$ is the Bohr radius, acting on a force microscope in the pico to femto Newton range.Comment: 9 pages, late

Distance learning in the conditions of Covid-19: problems and prospects of their solution

The problem of ensuring the quality of educational services is extremely important. It is known that the level of education and education as such are of great importance for most areas of life as an individual, and each country and the world as a whole. The authors of the article tried to analyze the current state of education, namely - distance education, in terms of transformational processes. In their study, the authors tried to take into account the total digitalization of education and objective reality in general, the introduction of innovative technologies, and took into account the factor of the pandemic, which in one way or another affected all processes of public life. The result of this study was a reflection on the main trends in the development of distance education and education in general, as well as general recommendations for improving the education system at both local and global levels. This study was conducted on the basis of a number of methods that allowed to make adequate generalizations about the state of distance education:  the methods of system analysis, comparative analysis, sociological method, the method of observation, methods of analysis and synthesis, the method of abstraction and the method of generalization of objective phenomena

Quantum correction to the Kubo formula in closed mesoscopic systems

We study the energy dissipation rate in a mesoscopic system described by the parametrically-driven random-matrix Hamiltonian H[\phi(t)] for the case of linear bias \phi=vt. Evolution of the field \phi(t) causes interlevel transitions leading to energy pumping, and also smears the discrete spectrum of the Hamiltonian. For sufficiently fast perturbation this smearing exceeds the mean level spacing and the dissipation rate is given by the Kubo formula. We calculate the quantum correction to the Kubo result that reveals the original discreteness of the energy spectrum. The first correction to the system viscosity scales proportional to v^{-2/3} in the orthogonal case and vanishes in the unitary case.Comment: 4 pages, 3 eps figures, REVTeX

Vortex Dynamics and the Hall-Anomaly: a Microscopic Analysis

We present a microscopic derivation of the equation of motion for a vortex in a superconductor. A coherent view on vortex dynamics is obtained, in which {\it both} hydrodynamics {\it and} the vortex core contribute to the forces acting on a vortex. The competition between these two provides an interpretation of the observed sign change in the Hall angle in superconductors with mean free path $l$ of the order of the coherence length $\xi$ in terms of broken particle-hole symmetry, which is related to details of the microscopic mechanism of superconductivity.Comment: 12 pages, late

High-throughput processing and normalization of one-color microarrays for transcriptional meta-analyses

<p>Abstract</p> <p>Background</p> <p>Microarray experiments are becoming increasingly common in biomedical research, as is their deposition in publicly accessible repositories, such as Gene Expression Omnibus (GEO). As such, there has been a surge in interest to use this microarray data for meta-analytic approaches, whether to increase sample size for a more powerful analysis of a specific disease (e.g. lung cancer) or to re-examine experiments for reasons different than those examined in the initial, publishing study that generated them. For the average biomedical researcher, there are a number of practical barriers to conducting such meta-analyses such as manually aggregating, filtering and formatting the data. Methods to automatically process large repositories of microarray data into a standardized, directly comparable format will enable easier and more reliable access to microarray data to conduct meta-analyses.</p> <p>Methods</p> <p>We present a straightforward, simple but robust against potential outliers method for automatic quality control and pre-processing of tens of thousands of single-channel microarray data files. GEO GDS files are quality checked by comparing parametric distributions and quantile normalized to enable direct comparison of expression level for subsequent meta-analyses.</p> <p>Results</p> <p>13,000 human 1-color experiments were processed to create a single gene expression matrix that subsets can be extracted from to conduct meta-analyses. Interestingly, we found that when conducting a global meta-analysis of gene-gene co-expression patterns across all 13,000 experiments to predict gene function, normalization had minimal improvement over using the raw data.</p> <p>Conclusions</p> <p>Normalization of microarray data appears to be of minimal importance on analyses based on co-expression patterns when the sample size is on the order of thousands microarray datasets. Smaller subsets, however, are more prone to aberrations and artefacts, and effective means of automating normalization procedures not only empowers meta-analytic approaches, but aids in reproducibility by providing a standard way of approaching the problem.</p> <p>Data availability: matrix containing normalized expression of 20,813 genes across 13,000 experiments is available for download at . Source code for GDS files pre-processing is available from the authors upon request.</p