Anomalous Charge Transport Properties and Band Flattening in Graphene: A Quasi-Relativistic Tight-Binding Study of Pseudo-Majorana States

Anomalous charge carrier transport in graphene is studied within a topologically nontrivial quasi-relativistic graphene model. The model predicts additional topological contributions, such as the Majorana-like mass-term correction to the ordinary ohmic component of the current, the spin-orbital-coupling, “Zitterbewegung”-effect corrections to conductivity in space, and time dispersion regime. The corrections appear due to non-Abelian quantum statistics for the charge carriers in graphene. The chiral anomaly of electrophysical and optical properties may emerge due to a deconfinement of the pseudo-Majorana quasiparticles. It has been shown that phenomena of negative differential conductivity, loss of universal far-infrared optical conductivity, and nonzero “minimal” direct-current conductivity in graphene occur due to flattening and vorticity of the pseudo-Majorana model graphene energy bands

On the Green function of linear evolution equations for a region with a boundary

We derive a closed-form expression for the Green function of linear evolution equations with the Dirichlet boundary condition for an arbitrary region, based on the singular perturbation approach to boundary problems.Comment: 9 page

ЭНЕРГОЭФФЕКТИВНОСТЬ СИСТЕМЫ ЭЛЕКТРОСНАБЖЕНИЯ МЕТРОПОЛИТЕНА С РЕКУПЕРАЦИЕЙ ЭЛЕКТРОЭНЕРГИИ ПРИ ТОРМОЖЕНИИ

Purpose. The purpose of the paper is to assess the efficiency of the subway power supply system, which uses a four-quadrant DC drive with energy recovery in the supply network in the braking mode. Methodology. We have applied the theory of electrical circuits and mathematical simulation in Matlab package. Results. The theoretical dependence of the efficiency of the electrical supply system with a bidirectional flow of energy on the coefficient of resistive short circuit at the load terminals has been obtained. The theoretical result is verified by modeling. Originality. The equivalent circuit of the subway power supply system with a four-quadrant DC drive and the possibility of energy recovery to the supply network in braking mode is developed, its parameters are determined, and the schedule of the electric train movement was set. Practical value. The use of the obtained dependencies and simulation results will allow to determine the direction of the future development of the subway power supply system and optimize its energy efficiency. Цель. Целью статьи является оценка КПД системы электроснабжения метрополитена, в которой используется четырёхквадрантный привод постоянного тока с рекуперацией энергии в питающую сеть в режиме торможения. Методика. Для проведения исследований использовалась теория электрических цепей, математическое моделирование в пакете Matlab. Результаты. Получена теоретическая зависимость КПД СЭ с двунаправленным потоком энергии от коэффициента резистивного короткого замыкания на клеммах нагрузки. Теоретический результат проверен моделированием. Научная новизна. Разработана эквивалентная схема системы электроснабжения метрополитена с четырёхквадрантным приводом постоянного тока и возможностью рекуперации энергии в питающую сеть в режиме торможения, определены её параметры, задан график движения электропоезда. Практическое значение. Использование полученных зависимостей и результатов моделирования позволит определить направление перспективного развития системы электроснабжения метрополитена, оптимизировать её энергоэффективность.

On one-dimensional Schroedinger problems allowing polynomial solutions

We discuss the explicit construction of the Schroedinger equations admitting a representation through some family of general polynomials. Almost all solvable quantum potentials are shown to be generated by this approach. Some generalization has also been performed in higher-dimensional problems.Comment: 17 page

Similarly Strong Purifying Selection Acts on Human Disease Genes of All Evolutionary Ages

A number of studies have showed that recently created genes differ from the genes created in deep evolutionary past in many aspects. Here, we determined the age of emergence and propensity for gene loss (PGL) of all human protein–coding genes and compared disease genes with non-disease genes in terms of their evolutionary rate, strength of purifying selection, mRNA expression, and genetic redundancy. The older and the less prone to loss, non-disease genes have been evolving 1.5- to 3-fold slower between humans and chimps than young non-disease genes, whereas Mendelian disease genes have been evolving very slowly regardless of their ages and PGL. Complex disease genes showed an intermediate pattern. Disease genes also have higher mRNA expression heterogeneity across multiple tissues than non-disease genes regardless of age and PGL. Young and middle-aged disease genes have fewer similar paralogs as non-disease genes of the same age. We reasoned that genes were more likely to be involved in human disease if they were under a strong functional constraint, expressed heterogeneously across tissues, and lacked genetic redundancy. Young human genes that have been evolving under strong constraint between humans and chimps might also be enriched for genes that encode important primate or even human-specific functions