Spin electric effects in molecular antiferromagnets

Molecular nanomagnets show clear signatures of coherent behavior and have a wide variety of effective low-energy spin Hamiltonians suitable for encoding qubits and implementing spin-based quantum information processing. At the nanoscale, the preferred mechanism for control of quantum systems is through application of electric fields, which are strong, can be locally applied, and rapidly switched. In this work, we provide the theoretical tools for the search for single molecule magnets suitable for electric control. By group-theoretical symmetry analysis we find that the spin-electric coupling in triangular molecules is governed by the modification of the exchange interaction, and is possible even in the absence of spin-orbit coupling. In pentagonal molecules the spin-electric coupling can exist only in the presence of spin-orbit interaction. This kind of coupling is allowed for both $s=1/2$ and $s=3/2$ spins at the magnetic centers. Within the Hubbard model, we find a relation between the spin-electric coupling and the properties of the chemical bonds in a molecule, suggesting that the best candidates for strong spin-electric coupling are molecules with nearly degenerate bond orbitals. We also investigate the possible experimental signatures of spin-electric coupling in nuclear magnetic resonance and electron spin resonance spectroscopy, as well as in the thermodynamic measurements of magnetization, electric polarization, and specific heat of the molecules.Comment: 31 pages, 24 figure

Quantum rings as electron spin beam splitters

Quantum interference and spin-orbit interaction in a one-dimensional mesoscopic semiconductor ring with one input and two output leads can act as a spin beam splitter. Different polarization can be achieved in the two output channels from an originally totally unpolarized incoming spin state, very much like in a Stern-Gerlach apparatus. We determine the relevant parameters such that the device has unit efficiency.Comment: 4 pages, 3 figures; minor change

Физико-математическая модель процесса взаимодействия СВЧ-сигнала с кристаллической структурой радиопоглощающего диэлектрика

За допомогою запропонованої в статті підходу можуть бути дослідженні перспективні способи отримання інформації про сучасні літальні апарати. Сучасна техніка створюється з використанням неметалічних матеріалів у своєї конструкції. Це зрозуміло за рядом причин, основною з яких є кращі характеристики речовин, що використовуються. Існуючі підходи щодо отримання радіолокаційної інформації про такі об’єкти є непідходящими оскільки вони засновані на використанні ефектів, що протікають в металах під час їх опромінення електромагнітним НВЧ полем. Проблемою є створення умов щодо дистанційної тимчасової зміни провідних властивостей для використання викликаних ефектів у існуючих способах радіолокації. Тенденція розвитку сучасних літальних засобів полягає у використанні неметалічних композитних матеріалів у конструкції планеру. Цей напрямок суттєво знижує можливості існуючих радіолокаційних засобів по виявленню та супроводженню таких літальних апаратів. Основний недолік існуючих метолів локації літальних апаратів полягає у використанні принципу „потужного сигналу”, тобто збільшенні потужності випроміненого зондуючого сигналу для підвищення рівня віддзеркаленого від повітряного об’єкту радіолокаційного сигналу і покращення прийомних характеристик РЛС виявлення.The use model can be marketed on stage of the finding and accompaniments radar station modern air integer. Mdeletion of increasing to efficiency antiradiolokation integer with artificially reduced. The task decrease of radar visibility a head part of a tracking can be decided by several ways, which optimize a configuration object and allow to achieve in signify at decrees an effective reflecting surface, as in this case it is necessary to lower the sizes, that is not always possible. So by the most effective way there is a development of the requirement to impedance. The technique of development of an impedance provides the account of a number the requirements, which stated in clause. The methods developed allows to evaluate dispersion of the part air object covered which different radio adsorbent material which gives the opportunity choose optimal from the point of view of air irradiation a reception angles frequency for mono static or di static radar station. There for having the results of the mathematics model it is possible to sub satiate and then performer adaptation and completing tasks for air complexes existing and being developed wile perfuming tasks on the radar visibility object.С помощью предложенного в статье подхода могут быть исследованы перспективные способы получения информации о современных летательных аппаратах. Современная техника разрабатывается с использованием неметаллических материалов. Это понятно по ряду причин, основной из которых есть лучшие характеристики веществ. Существующие подходы получения радиолокационной информации об объектах есть непригодными поскольку они основаны на применении эффектов, которые происходят в металлах. Проблемой есть создание условий дистанционного изменения свойств вещества. Тенденция развития летающих аппаратов состоит в использовании неметаллических материалов. Это направление снижает возможности РЛС по получению радиолокационной информации. Основной недостаток методов получения радиолокационной информации состоит в реализации принципа „мощного сигнала” для автоматического сопровождения воздушного объекта и улучшения приемных характеристик РЛС обнаружения

Role of Toll-Like Receptor 4 (TLR4) in the Development of Inflammatory Process in Skin of Psoriasis Patients

The objective of the research was to study the mechanisms of developing local immune inflammation considering changes in immunohistochemical expression of Toll-like receptor 4 (TLR4) in skin of psoriasis patients after systemic immunosuppressive therapy.Materials and methods. Immonohistochemical dynamic analysis of biopsy material taken from psoriaform skin areas in 62 psoriasis patients receiving systemic immunosuppressive therapy was made. Beyond that, to compare the results of the appropriate immunohistochemical examinations biopsy material from anterior abdominal wall taken after surgical intervention (e.g. hernia repair) in practically healthy persons of an appropriate age (5 patients) was studied. To determine the nature and area of local cellular immune and inflammatory reactions in skin of psoriasis patients, immunohistochemical techniques for determining TLR4 marker expression were used.Results and discussion. While studying TLR4 expression, background diffuse cytoplasmic and nuclear staining of epidermis, vascular endothelium and single macrophage cells were identified in psoriaform skin areas. The number of positive-stained epidermis cells was about 80%. After a course of systemic suppressive therapy with Etanercept during 3 months, immunohistochemical reaction to identify TLR4 expression allowed us to establish that both the number of positive-stained cells and response intensity in epidermis considerably reduced. The number of cells expressing TLR4 in the epidermis was up to 60%. Even after treatment, a considerable number of TLR4-positive dendrite cells with a greatly increased size and extended with their processes up to the horny layer were identified in the epidermis.Conclusions. The ligands activating toll-like receptors of macrophages and subsequent inflammatory reaction probably concentrate in epidermis dendrite cells as evidenced by immunohistochemical reactions. TLR4-positive macrophages after activation in dermal papilla migrate to the papilla base to be then included as a component of inflammatory perivascular infiltrates. After treatment, the number of cells (both dendrite and macrophage) with TLR expression significantly decreased. However, the background readiness to a burst of activity of toll-like receptors persists.

q-Functional Wick's theorems for particles with exotic statistics

In the paper we begin a description of functional methods of quantum field theory for systems of interacting q-particles. These particles obey exotic statistics and are the q-generalization of the colored particles which appear in many problems of condensed matter physics, magnetism and quantum optics. Motivated by the general ideas of standard field theory we prove the q-functional analogues of Hori's formulation of Wick's theorems for the different ordered q-particle creation and annihilation operators. The formulae have the same formal expressions as fermionic and bosonic ones but differ by a nature of fields. This allows us to derive the perturbation series for the theory and develop analogues of standard quantum field theory constructions in q-functional form.Comment: 15 pages, LaTeX, submitted to J.Phys.

Dispersively detected Pauli Spin-Blockade in a Silicon Nanowire Field-Effect Transistor

We report the dispersive readout of the spin state of a double quantum dot formed at the corner states of a silicon nanowire field-effect transistor. Two face-to-face top-gate electrodes allow us to independently tune the charge occupation of the quantum dot system down to the few-electron limit. We measure the charge stability of the double quantum dot in DC transport as well as dispersively via in-situ gate-based radio frequency reflectometry, where one top-gate electrode is connected to a resonator. The latter removes the need for external charge sensors in quantum computing architectures and provides a compact way to readout the dispersive shift caused by changes in the quantum capacitance during interdot charge transitions. Here, we observe Pauli spin-blockade in the high-frequency response of the circuit at finite magnetic fields between singlet and triplet states. The blockade is lifted at higher magnetic fields when intra-dot triplet states become the ground state configuration. A lineshape analysis of the dispersive phase shift reveals furthermore an intradot valley-orbit splitting $\Delta_{vo}$ of 145 $\mu$eV. Our results open up the possibility to operate compact CMOS technology as a singlet-triplet qubit and make split-gate silicon nanowire architectures an ideal candidate for the study of spin dynamics

Driven coherent oscillations of a single electron spin in a quantum dot

The ability to control the quantum state of a single electron spin in a quantum dot is at the heart of recent developments towards a scalable spin-based quantum computer. In combination with the recently demonstrated exchange gate between two neighbouring spins, driven coherent single spin rotations would permit universal quantum operations. Here, we report the experimental realization of single electron spin rotations in a double quantum dot. First, we apply a continuous-wave oscillating magnetic field, generated on-chip, and observe electron spin resonance in spin-dependent transport measurements through the two dots. Next, we coherently control the quantum state of the electron spin by applying short bursts of the oscillating magnetic field and observe about eight oscillations of the spin state (so-called Rabi oscillations) during a microsecond burst. These results demonstrate the feasibility of operating single-electron spins in a quantum dot as quantum bits.Comment: Total 25 pages. 11 pages main text, 5 figures, 9 pages supplementary materia

The optical module of the Baikal deep underwater neutrino telescope

A deep underwater Cherenkov telescope has been operating since 1993 in stages of growing size at 1.1 km depth in Lake Baikal. The key component of the telescope is the Optical Module (OM) which houses the highly sensitive phototube QUASAR-370. We describe design and parameters of the QUASAR-370, the layout of the optical module, the front-end electronics and the calibration procedures, and present selected results from the five-year operation underwater. Also, future developments with respect to a telescope consisting from several thousand OMs are discussed.Comment: 30 pages, 24 figure

LEGAL UNDERSTANDING OF TRANSACTION COSTS

Purposes: This paper is devoted to the legal understanding of transaction costs both as a concept and a method developed within the framework of the institutional economics discipline for analyzing the consequences of various kinds arising from the exchange of goods. This work is relevant due to the need to apply new interdisciplinary methodological approaches to solving the problems that classical jurisprudence faces. The authors gave legalized concepts of transaction and transaction costs. Methods: As the main task within the framework of this paper, the authors proposed a classification of transaction costs, with the help of which it is possible to analyze legal activity in various fields. The study was based on the works of foreign and Russian scientists, economists and lawyers. Results: In the paper, the authors found that the classification of transaction costs used in economics was created only for analyzing relationships within substantive law and using them to analyze other legal relationships seems to be quite problematic. As a result of the study, the authors developed a new classification of transaction costs, which can be used both for the analysis of substantive and procedural law. Also, they focus on certain aspects of various transaction costs. Implications/Applications: In this regard, a problem arises in creating a classification that would take into account the advantages of all these approaches, and would also be suitable for describing both substantive and procedural legal relations. Novelty/Originality: The development of domestic and foreign legal science is impossible without the use of interdisciplinary approaches, including not only the interaction of intersectoral relations, and this article has studied this issue

Experimental study of the decay KL0→π0ννˉK_L^0\to\pi^0\nu\bar{\nu}

The first dedicated search for the rare neutral-kaon decay $K_L^0\to\pi^0\nu\bar{\nu}$ has been carried out in the E391a experiment at the KEK 12-GeV proton synchrotron. The final upper limit of 2.6 $\times 10^{-8}$ at the 90% confidence level was set on the branching ratio for the decay.Comment: 23 pages, 27 figures, accepted for publication as a regular article in Physical Review