Coulomb blockade and transport in a chain of one-dimensional quantum dots

A long one-dimensional wire with a finite density of strong random impurities is modelled as a chain of weakly coupled quantum dots. At low temperature T and applied voltage V its resistance is limited by "breaks": randomly occuring clusters of quantum dots with a special length distribution pattern that inhibits the transport. Due to the interplay of interaction and disorder effects the resistance can exhibit T and V dependences that can be approximated by power laws. The corresponding two exponents differ greatly from each other and depend not only on the intrinsic electronic parameters but also on the impurity distribution statistics.Comment: 4 pages, 1 figure. Changes from v2: Dropped discussion of the high-field regime. Added discussion of mesoscopic fluctuations and multiple channels in the quasi-1D case. Improved presentation styl

Quantum creep and variable range hopping of one-dimensional interacting electrons

The variable range hopping results for noninteracting electrons of Mott and Shklovskii are generalized to 1D disordered charge density waves and Luttinger liquids using an instanton approach. Following a recent paper by Nattermann, Giamarchi and Le Doussal [Phys. Rev. Lett. {\bf 91}, 56603 (2003)] we calculate the quantum creep of charges at zero temperature and the linear conductivity at finite temperatures for these systems. The hopping conductivity for the short range interacting electrons acquires the same form as for noninteracting particles if the one-particle density of states is replaced by the compressibility. In the present paper we extend the calculation to dissipative systems and give a discussion of the physics after the particles materialize behind the tunneling barrier. It turns out that dissipation is crucial for tunneling to happen. Contrary to pure systems the new metastable state does not propagate through the system but is restricted to a region of the size of the tunneling region. This corresponds to the hopping of an integer number of charges over a finite distance. A global current results only if tunneling events fill the whole sample. We argue that rare events of extra low tunneling probability are not relevant for realistic systems of finite length. Finally we show that an additional Coulomb interaction only leads to small logarithmic corrections.Comment: 15 pages, 3 figures; references adde

Dynamic Fluctuation Phenomena in Double Membrane Films

Dynamics of double membrane films is investigated in the long-wavelength limit including the overdamped squeezing mode. We demonstrate that thermal fluctuations essentially modify the character of the mode due to its nonlinear coupling to the transversal shear hydrodynamic mode. The corresponding Green function acquires as a function of the frequency a cut along the imaginary semi-axis. Fluctuations lead to increasing the attenuation of the squeezing mode it becomes larger than the `bare' value.Comment: 7 pages, Revte

Characteristic properties of the microstructure and microtexture of medium-carbon steel subjected to sulfide stress cracking

Increasing the resistance of steel products to sulfide stress cracking (SSC) is one of the topical issues of the oil and gas industry. Among various factors determining the SSC resistance of a material is the structure-phase state of the material itself and the crystallographic texture associated with it. This paper analyzes these features using the scanning electron microscopy (SEM), transmission electron microscopy (TEM), and microroentgen electron backscattered diffraction (EBSD) techniques. As the research material, a production string (PS) coupling made of medium-carbon steel was selected, which collapsed by the mechanism of hydrogen embrittlement and subsequent SSC. For the first time, by the SEM method, using the location and mutual orientation of cementite (Fe3C) particles, at high magnifications, the authors demonstrated the possibilities of identifying the components of upper bainite, lower bainite, and tempered martensite in steels. The presence of the detected structural components of steel was confirmed by transmission electron microscopy (TEM). Using the EBSD method, the detailed studies of microtexture were conducted to identify the type and nature of the microcrack propagation. It is established that the processes of hydrogen embrittlement and subsequent SSC lead to the formation of {101} , {100} , {122} , {013} , {111} , {133} , {3 } grain orientations. It is shown that the strengthening of orientations of {001} , {100} , {112} , and {133} types worsens the SSC resistance of the material. Using the EBSD analysis method, the influence of coincident site lattice (CSL) grain boundaries on the nature of microcrack propagation is estimated. It is found that the Σ 3 CSL grain boundaries between the {122} and {111} , {012} , {100} plates of the upper bainite inhibit the microcrack development, and the Σ 13b, Σ 29a, and Σ 39a CSL grain boundaries, contribute to the accelerated propagation of microcracks. For comparative analysis, similar studies were carried out in an unbroken (original) coupling before operation

Capabilities of the GAMMA-400 gamma-ray telescope to detect gamma-ray bursts from lateral directions

The currently developing space-based gamma-ray telescope GAMMA-400 will measure the gamma-ray and electrons + positrons fluxes using the main top-down aperture in the energy range from ~20 MeV to several TeV in the highly elliptic orbit (without shadowing the telescope by the Earth and outside the radiation belts) continuously for a long time. The instrument will provide fundamentally new data on discrete gamma-ray sources, gamma-ray bursts (GRBs), sources and propagation of Galactic cosmic rays and signatures of dark matter due to its unique angular and energy resolutions in the wide energy range. The gamma-ray telescope consists of the anticoincidence system (AC), the converter-tracker (C), the time-of-flight system (S1 and S2), the position-sensitive and electromagnetic calorimeters (CC1 and CC2), the top and bottom scintillation detectors of the calorimeter (S3 and S4) and lateral detectors of the calorimeter (LD). In this paper, the capabilities of the GAMMA-400 gamma-ray telescope to measure fluxes of GRBs from lateral directions of CC2 are analyzed using Monte-Carlo simulations. The analysis is based on second-level trigger construction using signals from S3, CC2, S4 and LD detectors. For checking the numerical algorithm the data from space-based GBM and LAT instruments of the Fermi experiment are used, namely, three long bursts: GRB 080916C, GRB 090902B, GRB 090926A and one short burst GRB 090510A. The obtained results allow us to conclude that from lateral directions the GAMMA-400 space-based gamma-ray telescope will reliably measure the spectra of bright GRBs in the energy range from ~10 to ~100 MeV with the effective area of about 0.13 m2 (for each of the four sides of CC2) and total field of view of about 6 sr.Comment: 19 pages, 18 figures, the paper will be submitted to Advances in Space Researc

Heart Condition in Convalescents of Hemorrhagic Fever with Renal Syndrome According to Echocardiography Data

Aim. To study the morpho-functional parameters of the heart in convalescents of hemorrhagic fever with renal syndrome (HFRS) using echocardiography.Material and methods. The study included 27 patients without any chronic diseases who had severe or moderate HFRS (the main group) within 3 weeks after their discharge from the infection diseases hospital. The reference group consisted of 19 patients comparable by age and gender, without any chronic diseases. Transthoracic echocardiography was the basic method of heart and hemodynamics investigation. The test was performed using tissue Doppler and non-Doppler assessment of left ventricle systolic deformation method (speckle-tracking method).Results. Violation of longitudinal systolic deformation of the left ventricle was observed in 15 (55.6%) patients, which was combined with diastolic left ventricle filling by the type of relaxation violation in 8 (29.6%) cases. Mitral valve insufficiency of 1 degree was identified in 11 (40.7%) HFRS patients, insufficiency of the tricuspid valve of 1 degree was identified in 4 (14.8%) patients. Pericardial effusion was detected in 2 (7.4%) patients. In 7 (25.9%) patients in the first 3 weeks after discharge from the hospital, additional floating echoes were detected on the leaves and fibrous ring of the aortic valve, which were considered as a manifestation of thromboendocarditis.Conclusion. Further investigation is necessary to assess the prognostic value (including the risk of thromboembolic complication developing) of the changes revealed in HFRS convalescents and to support the inclusion of echocardiography in the examination program during dispensary observation of HFRS-convalescents

A facility to Search for Hidden Particles (SHiP) at the CERN SPS

A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.Comment: Technical Proposa

Люминолзависимая хемилюминесценция в диагностике и контроле эффективности лечения аспириновой бронхиальной астмы

The intensity of stimulated with non-specific activators luminol dependent blood hemiluminescence (ChL) was estimated with the presence of non-steroid antiinflammatory drugs (NAID) analgin and aspisol in 52 patients withaspirinic bronchial asthma. The control group contained 10 persons without pathology evidence and 11 patients with atopic bronchial asthma. The ChL coefficient Was 0.59±0.01 in patients with clinical signs of intolerance to NAID during the peroral analgin test and was 1.33+0.02 in the control group. The positive clinical desensitization effect was accompanied with the ChL coefficient increase. Thus, blood predincubation with NAID in patients with aspirinic bronchial asthma decreases the stimulated ChL intensity. The ChL test with NAID can be used to control the desensitisation effectivity.Исследовали интенсивность стимулированной неспецифическими активаторами люминол - зависимой хемилюминесценции (ХЛ) цельной крови 52 больных аспириновой бронхиальной астмой в присутствии нестероидных противовоспалительных средств (НПВС) — анальгина и аспизола. Контрольную группу составили 10 практически здоровых л и ц и 12 больных атопической бронхиальной астмой. У больных с клиническим и признаками непереносимости НПВС и положительной пероральной пробой с анальгином коэффициент ХЛ в пробе с этим препаратом составил 0,59+0,01, а в контрольной группе — 1,33+0,02. Положительный клинический эффект десенситизации сопровождался повышением коэффициента ХЛ. Таким образом, у больных аспириновой бронхиальной астмой предынкубация крови с НПВС снижает интенсивность стимулированной ХЛ. Хемилюминесцентный тест с НПВС может быть использован для контроля эффективности десенситизации

Observation of two new Ξb−\Xi_b^- baryon resonances

Two structures are observed close to the kinematic threshold in the $\Xi_b^0 \pi^-$ mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb$^{-1}$ recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content $bds$ are expected in this mass region: the spin-parity $J^P = \frac{1}{2}^+$ and $J^P=\frac{3}{2}^+$ states, denoted $\Xi_b^{\prime -}$ and $\Xi_b^{*-}$. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be $m(\Xi_b^{\prime -}) - m(\Xi_b^0) - m(\pi^{-}) = 3.653 \pm 0.018 \pm 0.006$ MeV$/c^2$, $m(\Xi_b^{*-}) - m(\Xi_b^0) - m(\pi^{-}) = 23.96 \pm 0.12 \pm 0.06$ MeV$/c^2$, $\Gamma(\Xi_b^{*-}) = 1.65 \pm 0.31 \pm 0.10$ MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of $\Gamma(\Xi_b^{\prime -}) < 0.08$ MeV at 95% confidence level. Relative production rates of these states are also reported.Comment: 17 pages, 2 figure

Precision measurement of CPCP violation in Bs0→J/ψK+K−B_s^0 \to J/\psi K^+K^- decays

The time-dependent $CP$ asymmetry in $B_s^0 \to J/\psi K^+K^-$ decays is measured using $pp$ collision data, corresponding to an integrated luminosity of $3.0$fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of $7$ and $8$TeV. In a sample of 96 000 $B_s^0 \to J/\psi K^+K^-$ decays, the $CP$-violating phase $\phi_s$ is measured, as well as the decay widths $\Gamma_{L}$ and $\Gamma_{H}$ of the light and heavy mass eigenstates of the $B_s^0-\bar{B}_s^0$ system. The values obtained are $\phi_s = -0.058 \pm 0.049 \pm 0.006$ rad, $\Gamma_s \equiv (\Gamma_{L}+\Gamma_{H})/2 = 0.6603 \pm 0.0027 \pm 0.0015$ps$^{-1}$, and$\Delta\Gamma_s \equiv \Gamma_{L} - \Gamma_{H} = 0.0805 \pm 0.0091 \pm 0.0032$ps$^{-1}$, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of those quantities to date. A combined analysis with $B_s^{0} \to J/\psi \pi^+\pi^-$ decays gives $\phi_s = -0.010 \pm 0.039$rad. All measurements are in agreement with the Standard Model predictions. For the first time the phase $\phi_s$ is measured independently for each polarisation state of the $K^+K^-$ system and shows no evidence for polarisation dependence.Comment: 6 figure