Реализация образовательных технологий в условиях Интернета как глобальной коммуникационной среды

The article deals with the implementation of educational technology in the Internet as a global communications medium. The features of training based on social services in modern conditions.Рассмотрены вопросы, связанные с реализацией образовательных технологий в условиях Интернета как глобальной коммуникационной среды. Рассматриваются особенности организации обучения на основе социальных сервисов в современных условиях

Experimental studies of light-wave phase shift by polymer dispersed liquid crystal films

Polymermethacrylate (PMMA) and polyvinyl butyral (PVB) thin films with the dispersed liquid crystal droplets are prepared by the described technique. The measurements of light wave polarization-independent phase shift induced by the electric field are displayed. It was been shown that the phase shift in polymethylmethacrylate films can approach five radians at the applied electric field about 10 V/μm

Evidence for superconductivity and a pseudogap in the new magnetic compound PrAg₆In₆

Direct evidence for superconductivity in the new magnetic compound PrAg₆In₆ is revealed for the first time. The distinct Andreev-reflection current is observed in metallic point contacts (PC) based on this compound. The data obtained provide reason enough to suggest that the rise of superconductivity strongly depends on the local magnetic order varying over the sample volume. The triangular-shaped PC spectra (dV/dI V ( )) in the vicinity of the zero-bias voltage suggest an unconventional type of superconducting pairing. As follows from the temperature and magnetic field dependences of the PC spectra, the superconducting energy gap structure transforms into the pseudogap one as the temperature or the magnetic field increases

Direct evidence for the occurrence of superconductivity in the magnetic compound YFe₄Al₈

For the first time we present the direct evidence for superconductivity in the ternary magnetic compound YFe₄Al₈ with the ThMn₁₂ type structure found via point-contact (PC) experiments on contacts between silver needle and single-crystal YFe₄Al₈, revealing the distinct Andreev-reflection current. The spectra measured prove the existence of normal-superconducting interface and exhibit the triangular-like shape in a vicinity of zero-bias voltage, inferring the unconventional type of superconductivity. The derived dependences of the order parameter versus temperature Δ(T) and m agnetic field Δ(H) are presented. Δ(T) follows BCS theory, whereas Δ(H) do not satisfy any theoretical predictions. In some cases there exists noticeable superconductivity enhancement by a weak magnetic field. The data obtained imply the v ery inhomogeneous distribution of superconductivity over the sample volume in spite of its single crystal structure. We assume that the reason is associated with inherent magnetic inhomogeneities of this material. The highest values for the critical temperature Tc, upper critical magnetic field Hc₂, and ratio 2Δ(0)/kTc are 7.4 K, 5 T, and 7.2, respectively

Single-photon emitters in GaSe

Single-photon sources are important building blocks for quantum information technology. Emitters based on solid-state systems provide a viable route to integration in photonic devices. Here, we report on single-photon emitters in the layered semiconductor GaSe. We identify the exciton and biexciton transition of the quantum emitters with power-dependent photoluminescence and photon statistics measurements. We find evidence that the localization of the excitons is related to deformations of the GaSe crystal, caused by nanoscale selenium inclusions, which are incorporated in the crystal. These deformations give rise to local strain fields, which induce confinement potentials for the excitons. This mechanism lights the way for the controlled positioning of single-photon emitters in GaSe on the nanoscale

Photoluminescence of two-dimensional GaTe and GaSe films

Gallium chalcogenides are promising building blocks for novel van der Waals heterostructures. We report on the low-temperature micro-photoluminescence (PL) of GaTe and GaSe films with thicknesses ranging from 200 nm to a single unit cell. In both materials, PL shows a dramatic decrease by 10e4–10e5 when film thickness is reduced from 200 to 10 nm. Based on evidence from continuous-wave (cw) and time-resolved PL, we propose a model explaining the PL decrease as a result of non-radiative carrier escape via surface states. Our results emphasize the need for special passivation of two-dimensional films for optoelectronic applications

Polarizing a stored proton beam by spin flip?

We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.Comment: 18 pages, 6 figure

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available