Effect of Coulomb correlation on electron transport through concentric quantum ring-quantum dot structure

We theoretically study the single electron transfer through two-terminal quantum ring capacitively coupled to charged dot placed in its center. For this purpose we solve time-dependent Schrodinger equation for fully correlated two-particle system constituted by the transferred electron and the second particle confined in the dot. Analysis of transmission probability dependence on magnetic field in Ahronov-Bohm effect indicates that the maxima of transmission probability may be enhanced as well as reduced for attractive or repulsive Coulomb interaction respectively. The existence of Coulomb correlation in the system may also lead to inelastic scattering of the transferred electron. In such case, transmission of electron thorugh the ring is not completely blocked for (n+1/2) magnetic flux quanta

Few-electron artificial molecules formed by laterally coupled quantum rings

We study the artificial molecular states formed in laterally coupled double semiconductor nanorings by systems containing one, two and three electrons. An interplay of the interring tunneling and the electron-electron interaction is described and its consequences for the magnetization and charging properties of the system are determined. It is shown that both the magnetic dipole moment generated by the double ring structure and the chemical potential of the system as function of the external magnetic field strongly depend on the number of electrons and the interring barrier thickness. Both the magnetization and chemical potentials exhibit cusps at the magnetic fields inducing ground-state parity and / or spin transformations. The symmetry transformations are discussed for various tunnel coupling strengths: from rings coupled only electrostatically to the limit of coalesced rings. We find that in the ground-states for rings of different radii the magnetic field transfers the electron charge from one ring to the other. The calculations are performed with the configuration interaction method based on an approach of Gaussian functions centered on a rectangular array of points covering the studied structure. Electron-electron correlation is also discussed

Los esfuerzos para combatir el crimen organizado en Brasil

In recent decades organized crime has ceased to be an isolated issue concerning only a single country. The negative consequences of this phenomenon spread out of the state borders and cause a danger for public security, democratic institutions and economic stability. The struggle against organized crime requires the coordinated cooperation of the law enforcement, judiciary and other institutions responsible for the prevention, detection, prosecution, and sanctioning of the criminal activity.The article studies some aspects of this phenomenon in Brazil. It discusses the factors that have contributed to the development of organized crime in this most influential country of South America. The paper also examines various initiatives that have been taken by Brazilian authorities in the efforts to combat organized crime.En las últimas décadas el crimen organizado se ha convertido en un importante problema para la seguridad internacional. La delincuencia organizada representa una gran amenaza para la seguridad pública, a las instituciones democráticas y para la estabilidad económica. La lucha contra este fenómeno requiere la cooperación policial y judicial en materia de prevención, detección, investigación y sanción de los delitos cometidos por organizaciones criminales.El artículo presenta y analiza algunos aspectos relevantes del crimen organizado en Brasil. Además, describe los factores que han influido en el desarrollo de la delincuencia organizada en este país. El artículo examina también las iniciativas tomadas por las autoridades brasileñas para combatir el crimen organizado

Stability of negative and positive trions in quantum wires

Binding energies of negative ($X^-$) and positive trions ($X^+$) in quantum wires are studied for strong quantum confinement of carriers which results in a numerical exactly solvable model. The relative electron and hole localization has a strong effect on the stability of trions. For equal hole and electron confinement, $X^+$ is more stable but a small imbalance of the particle localization towards a stronger hole localization e.g. due to its larger effective mass, leads to the interchange of $X^-$ and $X^+$ recombination lines in the photoluminescent spectrum as was recently observed experimentally. In case of larger $X^-$ stability, a magnetic field oriented parallel to the wire axis leads to a stronger increase of the $X^+$ binding energy resulting in a crossing of the $X^+$ and $X^-$ lines

The impact of the "migrant crisis" on the security of Germany and Poland

This paper aims to study the impact of the “migrant crisis” in 2015 and 2016 on German and Polish security. The article is divided into three parts. The first presents the causes and the evolution of the “migrant crisis” in the European Union. The second part compares previous migration experiences of Germany and Poland. The third part examines the state security implications of the last “crisis”. According to the author, the real impact of the migration processes on the state security is largely determined by the capacity of a government to deal with the changes that occur

Analiza wpływu wilgotności i temperatury powietrza na wartość współczynnika przewodności cieplnej λ materiałów termoizolacyjnych stosowanych wewnątrz pomieszczeń

The aim of the article is to present the issues related to the use of climate panels as insulating materials used inside buildings. The study involved four materials, the two of them is a lightweight cellular concrete, the other two were produced on the basis of lime silicate. The main aim of the laboratory tests was to determine the coefficient of thermal conductivity λ depending on the changing temperature and humidity. Based on research the sorption materials curves were determined. The study allows you to specify the amount of moisture that can be accepted by the material in specific temperature and humidity conditions. In addition, the examined coefficients of thermal conductivity compared with the values declared by suppliers to assess compliance with the data contained in the data sheet.Artykuł ma na celu przybliżenie problematyki związanej z wykorzystywaniem płyt klimatycznych jako materiałów termoizolacyjnych stosowanych wewnątrz pomieszczeń. Badaniom poddano cztery materiały, dwa z nich to lekkie betony komórkowe pozostałe dwa wyprodukowano na bazie silikatów wapiennych. Głównym celem badań laboratoryjnych było wyznaczenie współczynnika przewodności cieplnej λ w zależności od zmieniających się wartości wilgotności i temperatury. Na podstawie badań wyznaczono również krzywe sorpcyjne materiałów. Badanie to umożliwia określenie ilości wilgoci, jaką może przyjąć materiał w danych warunkach cieplno-wilgotnościowych. Ponadto zbadane współczynniki przewodności cieplnej porównano z wartościami deklarowanymi przez producentów materiałów celem oceny zgodności z danymi zawartymi w kartach technicznych