Temperature-dependent magnetospectroscopy of HgTe quantum wells

We report on magnetospectroscopy of HgTe quantum wells in magnetic fields up to 45 T in temperature range from 4.2 K up to 185 K. We observe intra- and inter-band transitions from zero-mode Landau levels, which split from the bottom conduction and upper valence subbands, and merge under the applied magnetic field. To describe experimental results, realistic temperature-dependent calculations of Landau levels have been performed. We show that although our samples are topological insulators at low temperatures only, the signature of such phase persists in optical transitions at high temperatures and high magnetic fields. Our results demonstrate that temperature-dependent magnetospectroscopy is a powerful tool to discriminate trivial and topological insulator phases in HgTe quantum wells

Phase diagrams of magnetopolariton gases

The magnetic field effect on phase transitions in electrically neutral bosonic systems is much less studied than those in fermionic systems, such as superconducting or ferromagnetic phase transitions. Nevertheless, composite bosons are strongly sensitive to magnetic fields: both their internal structure and motion as whole particles may be affected. A joint effort of ten laboratories has been focused on studies of polariton lasers, where non-equilibrium Bose-Einstein condensates of bosonic quasiparticles, exciton-polaritons, may appear or disappear under an effect of applied magnetic fields. Polariton lasers based on pillar or planar microcavities were excited both optically and electrically. In all cases a pronounced dependence of the onset to lasing on the magnetic field has been observed. For the sake of comparison, photon lasing (lasing by an electron-hole plasma) in the presence of a magnetic field has been studied on the same samples as polariton lasing. The threshold to photon lasing is essentially governed by the excitonic Mott transition which appears to be sensitive to magnetic fields too. All the observed experimental features are qualitatively described within a uniform model based on coupled diffusion equations for electrons, holes and excitons and the Gross-Pitaevskii equation for exciton-polariton condensates. Our research sheds more light on the physics of non-equilibrium Bose-Einstein condensates and the results manifest high potentiality of polariton lasers for spin-based quantum logic applications.Comment: 21 pages, 11 figure

Interaction of the single-particle and collective degrees of freedom in non-magic nuclei: the role of phonon tadpole terms

A method of a consistent consideration of the phonon contributions to mass and gap operators in non-magic nuclei is developed in the so-called g^2 approximation, where g is the low-lying phonon creation amplitude. It includes simultaneous accounting for both the usual non-local terms and the phonon tadpole ones. The relations which allow the tadpoles to be calculated without any new parameters are derived. As an application of the results, the role of the phonon tadpoles in the single-particle strength distribution and in the single-particle energies and gap values has been considered. Relation to the problem of the surface nature of pairing is discussed.Comment: 22 pages, 7 figure

Luminescence mechanism and energy transfer in cesium metavanadate CsVO 3

Photoluminescence properties and relaxation dynamics of electronic excitations in cesium vanadate CsVO 3 have been studied upon pulse laser excitation in the wide temperature range of 6.5–300 K. A vibronic structure observed in low-temperature PL spectra is considered and interpreted. Peculiarities of luminescence relaxation dynamics and emission spectra of CsVO 3 along with the appearance of the vibronic structure are explained in terms of strong electron-phonon coupling of excited electronic states and centrosymmetric vibrational modes in [VO 4 ] 3- center. A new approach in an interpretation of luminescence processes in vanadates is demonstrated. © 2019 Elsevier Ltd16.5186.2017/8.9The work was supported by Act 211 Government of the Russian Federation , contract № 02.A03.21.0006 . I.A.W. thanks for financial support Minobrnauki initiative research project № 16.5186.2017/8.9 . Authors thank Dr. Mathijs de Jong (Utrecht University) for his kind assistance in laser experiments and Prof. Boris V. Shulgin for fruitful discussions of this work

Signal-averaged P wave analysis for delineation of interatrial conduction – Further validation of the method

<p>Abstract</p> <p>Background</p> <p>The study was designed to investigate the effect of different measuring methodologies on the estimation of P wave duration. The recording length required to ensure reproducibility in unfiltered, signal-averaged P wave analysis was also investigated. An algorithm for automated classification was designed and its reproducibility of manual P wave morphology classification investigated.</p> <p>Methods</p> <p>Twelve-lead ECG recordings (1 kHz sampling frequency, 0.625 <it>μ</it>V resolution) from 131 healthy subjects were used. Orthogonal leads were derived using the inverse Dower transform. Magnification (100 times), baseline filtering (0.5 Hz high-pass and 50 Hz bandstop filters), signal averaging (10 seconds) and bandpass filtering (40–250 Hz) were used to investigate the effect of methodology on the estimated P wave duration. Unfiltered, signal averaged P wave analysis was performed to determine the required recording length (6 minutes to 10 s) and the reproducibility of the P wave morphology classification procedure. Manual classification was carried out by two experts on two separate occasions each. The performance of the automated classification algorithm was evaluated using the joint decision of the two experts (i.e., the consensus of the two experts).</p> <p>Results</p> <p>The estimate of the P wave duration increased in each step as a result of magnification, baseline filtering and averaging (100 ± 18 vs. 131 ± 12 ms; P < 0.0001). The estimate of the duration of the bandpass-filtered P wave was dependent on the noise cut-off value: 119 ± 15 ms (0.2 <it>μ</it>V), 138 ± 13 ms (0.1 <it>μ</it>V) and 143 ± 18 ms (0.05 <it>μ</it>V). (P = 0.01 for all comparisons).</p> <p>The mean errors associated with the P wave morphology parameters were comparable in all segments analysed regardless of recording length (95% limits of agreement within 0 ± 20% (mean ± SD)). The results of the 6-min analyses were comparable to those obtained at the other recording lengths (6 min to 10 s).</p> <p>The intra-rater classification reproducibility was 96%, while the interrater reproducibility was 94%. The automated classification algorithm agreed with the manual classification in 90% of the cases.</p> <p>Conclusion</p> <p>The methodology used has profound effects on the estimation of P wave duration, and the method used must therefore be validated before any inferences can be made about P wave duration. This has implications in the interpretation of multiple studies where P wave duration is assessed, and conclusions with respect to normal values are drawn.</p> <p>P wave morphology and duration assessed using unfiltered, signal-averaged P wave analysis have high reproducibility, which is unaffected by the length of the recording. In the present study, the performance of the proposed automated classification algorithm, providing total reproducibility, showed excellent agreement with manually defined P wave morphologies.</p

Invasive meningococcal disease in three siblings with hereditary deficiency of the 8th component of complement: Evidence for the importance of an early diagnosis

Deficiency of the eighth component of complement (C8) is a very rare primary immunodeficiency, associated with invasive, recurrent infections mainly caused by Neisseria species. We report functional and immunochemical C8 deficiency diagnosed in three Albanian siblings who presented with severe meningococcal infections at the age of 15 years, 4 years and 17 months, respectively. The youngest suffered serious complications (necrosis of fingers and toes requiring amputation). METHODS: Functional activity of the classical, alternative and mannose-binding lectin complement pathways was measured in serum from the 3 siblings and their parents (37-year-old woman and 42-year-old man). Forty healthy subjects (20 males and 20 females aged 4-38 years) served as normal controls. Serum complement factors were measured by haemolytic assays and immunoblotting. Sequence DNA analysis of the C8B gene was performed. RESULTS: Analyses of the three complement pathways revealed no haemolytic activity and also absence of C8beta in serum samples from all three siblings. The genetic analysis showed that the three siblings were homozygous for the p.Arg428* mutation in the C8B gene on chromosome 1p32 (MIM 120960). The parents were heterozygous for the mutation and presented normal complement activities. A 2-year follow-up revealed no further infective episodes in the siblings after antibiotic prophylaxis and meningococcal vaccination. CONCLUSIONS: Complement deficiencies are rare and their occurrence is often underestimated. In presence of invasive meningococcal infection, we highlight the importance of complement screening in patients and their relatives in order to discover any genetic defects which would render necessary prophylaxis to prevent recurrent infections and severe complications

Development of Grazing Incidence Multilayer Mirrors for Hard X-ray Focusing Telescopes

We are developing depth-graded, multilayer-coated mirrors for astrophysical hard X-ray focusing telescopes. In this paper, we discuss the primary technical challenges associated with the multilayer coatings, and report on progress to date. We have sputtered constant cl-spacing and depth-graded W / Si multilayers onto 0.3- 0.5 mm thick DURAN glass (AF45 and D263) and 0.4 mm thick epoxy replicated aluminum foils (ERAFs) , both of which are potential mirror substrates. We have characterized the interfacial roughness, uniformity, and stress of the coatings. The average interfacial roughness of each multilayer was measured from specular reflectivity scans (Bi = Br) using Cu K0 X-rays. The thin film stress was calculated from the change in curvature induced by the coating on flat glass substrates. Thickness and roughness uniformity were measured by taking specular reflectivity scans of a multilayer deposited on the inside surface of a quarter cylinder section. We found that interfacial roughness (a) in the multilayers was typically between 3.5 and 4.0 A on DESAG glass, and between 4.5 and 5.0 A on the ERAFs. Also, we found that coatings deposited on glass that has been thermally formed into a cylindrical shape performed as well as flat glass. The film stress, calculated from Stoney's equation, for a 200 layer graded multilayer was approximately 200 MPa. Our uniformity measurements show that with no baffles to alter the deposition profile on a curved optic, the layer thickness differs by "'203 between the center and the edge of the optic. Interfacial roughness, however, remained constant, around 3.6 A, throughout the curved piece, even as the layer spacing dropped off

Induced Parity Nonconserving Interaction and Enhancement of Two-Nucleon Parity Nonconserving Forces

Two-nucleon parity nonconserving (PNC) interaction induced by the single-particle PNC weak potential and the two-nucleon residual strong interaction is considered. An approximate analytical formula for this Induced PNC Interaction (IPNCI) between proton and neutron is derived ($Q({\bf r} {\bf \sigma}_{p} \times {\bf \sigma}_{n}) \delta({\bf r}_{p}-{\bf r}_{n})$), and the interaction constant is estimated. As a result of coherent contributions from the nucleons to the PNC potential, IPNCI is an order of magnitude stronger ($\sim A^{1/3}$) than the residual weak two-nucleon interaction and has a different coordinate and isotopic structure (e.g., the strongest part of IPNCI does not contribute to the PNC mean field). IPNCI plays an important role in the formation of PNC effects, e.g., in neutron-nucleus reactions. In that case, it is a technical way to take into account the contribution of the distant (small) components of a compound state which dominates the result. The absence of such enhancement ($\sim A^{1/3}$) in the case of T- and P-odd interaction completes the picture.Comment: Phys. Rev. C, to appear; 17 pages, revtex 3, no figure