Nuclear magnetic resonance spectrum of 31P donors in silicon quantum computer

The influence of the electric field created by a gate potential of the silicon quantum computer on the hyperfine interaction constant (HIC) is obtained. The errors due to technological inaccuracy of location of donor atoms under a gate are evaluated. The energy spectra of electron-nuclear spin system of two interacting donor atoms with various values of HIC are calculated. The presence of two pairs of anticrossing levels in the ground electronic state is shown. Parameters of the structure at which errors rate can be greatly minimized are found.Comment: 12 pages,, 3 figure

Fluctuations of Quantum Entanglement

It is emphasized that quantum entanglement determined in terms of the von Neumann entropy operator is a stochastic quantity and, therefore, can fluctuate. The rms fluctuations of the entanglement entropy of two-qubit systems in both pure and mixed states have been obtained. It has been found that entanglement fluctuations in the maximally entangled states are absent. Regions where the entanglement fluctuations are larger than the entanglement itself (strong fluctuation regions) have been revealed. It has been found that the magnitude of the relative entanglement fluctuations is divergent at the points of the transition of systems from an entangled state to a separable state. It has been shown that entanglement fluctuations vanish in the separable states.Comment: 5 pages, 4 figure

Analysis of Transient Recovery Voltage and Secondary arc Current in Transposed Extra-High Voltage Lines in a Two-Phase Auto-Reclosing

Extra-high voltage (EHV) lines of 500–750 kV, providing transmission of electricity over long distances and at the same time performing the functions of intersystem communication at the level of the national power system, play an important role not only in normal modes, but also in emergency modes, ensuring the dynamic stability of the power system as a whole. In these lines, the overwhelming proportion of power cuts are caused by single-phase short circuits (90%), a significant part of which, being unstable arc faults, are successfully eliminated in the single-phase auto-reclosing cycle. Also, about 5%–10% of failures can be constituted by two-phase short circuits, which can be eliminated in a two-phase auto-reclosing cycle (TPhAR). The purpose of this paper is to study two-phase auto-reclosing in transposed EHV lines equipped with four-radial shunt reactors (ShR). The paper analyzes the efficiency of using a two-phase auto-reclosing to eliminate two-phase short-circuits in the lines connecting the power systems of Kyrgyzstan and Tajikistan. An algorithm is proposed for calculating the transient recovering voltages (TRV) and secondary arc currents (SAC) in the real transposed line Datka–Khujand–Dushanbe. The obtained results of TRV and SAC, which are within the permissible limits for the Dushanbe–Khujand line section, make it possible to have a dead time of TPhAR of no more than 0.6 s, in order to maintain the dynamic stability of the power system. For lines with a length of about 500 km (Datka–Khujand), equipped with three reactors, a successful TPhAR is impossible due to the appearance of resonant TRV in the circuit. The paper proposes the use of banks of capacitors connected in series in the phases of the ShR for the implementation of a successful TPhAR with the duration of the required pause of about 0.6 s. © 2021 The Authors

Quantum Entanglement in Nitrosyl Iron Complexes

Recent magnetic susceptibility measurements for polycrystalline samples of binuclear nitrosyl iron complexes [Fe_2(C_3H_3N_2S)_2(NO)_4] (I) and [Fe_2(SC_3H_5N_2)_2(NO)_4] (II), suggest that quantum-mechanical entanglement of the spin degrees of freedom exists in these compounds. Entanglement E exists below the temperature T_E that we have estimated for complexes I and II to be 80-90 and 110-120 K, respectively. Using an expression of entanglement in terms of magnetic susceptibility for a Heisenberg dimer, we find the temperature dependence of the entanglement for complex II. Having arisen at the temperature T_E, the entanglement increases monotonically with decreasing temperature and reaches 90-95% in this complex at T=25 K, when the subordinate effects are still small.Comment: 8 page

A pan-Arctic initiative on the spatial and temporal dynamics of Arctic coasts

Permafrost coasts make up roughly one third of all coasts worldwide. Their erosion leads to the release of previously locked organic carbon, changes in ecosystems and the destruction of cultural heritage, infrastructure and whole communities. Since rapid environmental changes lead to an intensification of Arctic coastal dynamics, it is of great importance to adequately quantify current and future coastal changes. However, the remoteness of the Arctic and scarcity of data limit our understanding of coastal dynamics at a pan-Arctic scale and prohibit us from getting a complete picture of the diversity of impacts on the human and natural environment. In a joint effort of the EU project NUNATARYUK and the NSF project PerCS-Net, we seek to close this knowledge gap by collecting and analyzing all accessible high-resolution shoreline position data for the Arctic coastline. These datasets include geographical coordinates combined with coastal positions derived from archived data, surveying data, air and space born remote sensing products, or LiDAR products. The compilation of this unique dataset will enable us to reach unprecedented data coverage and will allow us a first insight into the magnitude and trends of shoreline changes on a pan-Arctic scale with locally highly resolved temporal and spatial changes in shoreline dynamics. By comparing consistently derived shoreline change data from all over the Arctic we expect that the trajectory of coastal change in the Arctic becomes evident. A synthesis of some initial results will be presented in the 2020 Arctic Report Card on Arctic Coastal Dynamics. This initiative is an ongoing effort – new data contributions are welcome

Клиническое значение мутаций в генах репарации ДНК у больных метастатическим раком предстательной железы

Prostate cancer (PCa) is one of the most common malignant tumor in men. Significant advances have been made in the early detection and treatment of localized PCa, but metastatic castration-resistant PCa (mCRPC) remains one of the most challenging problems to treat in oncology. To improve treatment outcomes for patients at this stage of the disease, it is necessary to develop personalized therapy options based on the definition of biological predictors. In mCRPC, mutations in DNA repair genes are detected in ~23 % of patients with mCRPC. Detection of these mutations in patients with PCa has important clinical relevance. PCa with mutations in DNA repair genes may be sensitive to poly(ADP-ribose)-polymerase (PARP) inhibitors. Several studies II and III phase have demonstrated the effectiveness of PARP inhibitors with a high objective response rate in the treatment of mCRPC in patients with mutations in the DNA repair genes, which is definitely a more personalized approach to treatment. Identification of hereditary mutations in DNA repair genes is an important prognostic factor for the proband's relatives (for both men and women), which can later be used for genetic counseling of patients and the application of strategies to reduce the risk of malignant diseases.Рак предстательной железы (РПЖ) — одно из наиболее распространенных злокачественных новообразований у мужчин. Достигнуты значительные успехи в раннем выявлении и лечении локализованного РПЖ, однако метастатический кастрационно-резистентный РПЖ (мКРРПЖ) остается одной из наиболее сложных для лечения проблем в онкоурологии. Для улучшения результатов лечения пациентов на этой стадии заболевания необходима разработка персонализированных вариантов терапии, основанных на определении биологических предикторов. При мКРРПЖ мутации в генах репарации ДНК выявляют у ~23 % больных мКРРПЖ. Обнаружение данных мутаций у пациентов с РПЖ имеет важную клиническую значимость. РПЖ с мутациями в генах репарации ДНК может быть чувствителен к ингибиторам поли(АДФ-рибоза)-полимеразы (poly(ADP-ribose)-polymerase, PARP). В нескольких исследованиях II и III фаз продемонстрирована эффективность ингибиторов PARP с высокой частотой объективных ответов в лечении мКРРПЖ у пациентов с мутациями в генах репарации ДНК, что, несомненно, является более персонифицированным подходом в лечении. Идентификация наследственных мутаций в генах репарации ДНК — важный прогностический фактор для родственников пробанда (как для мужчин, так и для женщин), который в дальнейшем может использоваться для генетического консультирования пациентов и применения стратегии снижения риска злокачественных заболеваний