439 research outputs found
Direct Evidence of Two Superconducting Gaps in FeSeTe: SnS-Andreev Spectroscopy and Lower Critical Field
We present direct measurements of the superconducting order parameter in
nearly optimal FeSeTe single crystals with critical temperature
K. Using intrinsic multiple Andreev reflection effect (IMARE)
spectroscopy and measurements of lower critical field, we directly determined
two superconducting gaps, meV and meV, and their temperature dependences. We show that a two-band
model fits well the experimental data. The estimated electron-boson coupling
constants indicate a strong intraband and a moderate interband interaction
Three-loop contribution of the Faddeev-Popov ghosts to the -function of supersymmetric gauge theories and the NSVZ relation
We find the three-loop contribution to the -function of
supersymmetric gauge theories regularized by higher covariant derivatives
produced by the supergraphs containing loops of the Faddeev--Popov ghosts. This
is done using a recently proposed algorithm, which essentially simplifies such
multiloop calculations. The result is presented in the form of an integral of
double total derivatives in the momentum space. The considered contribution to
the -function is compared with the two-loop anomalous dimension of the
Faddeev--Popov ghosts. This allows verifying the validity of the NSVZ equation
written as a relation between the -function and the anomalous dimensions
of the quantum superfields. It is demonstrated that in the considered
approximation the NSVZ equation is satisfied for the renormalization group
functions defined in terms of the bare couplings. The necessity of the
nonlinear renormalization for the quantum gauge superfield is also confirmed.Comment: 20 pages, 4 figures, minor corrections, the final version to appear
in Eur.Phys.J.
Signal recognition and background suppression by matched filters and neural networks for Tunka-Rex
The Tunka Radio Extension (Tunka-Rex) is a digital antenna array, which
measures the radio emission of the cosmic-ray air-showers in the frequency band
of 30-80 MHz. Tunka-Rex is co-located with TAIGA experiment in Siberia and
consists of 63 antennas, 57 of them are in a densely instrumented area of about
1 km\textsuperscript{2}. In the present work we discuss the improvements of the
signal reconstruction applied for the Tunka-Rex. At the first stage we
implemented matched filtering using averaged signals as template. The
simulation study has shown that matched filtering allows one to decrease the
threshold of signal detection and increase its purity. However, the maximum
performance of matched filtering is achievable only in case of white noise,
while in reality the noise is not fully random due to different reasons. To
recognize hidden features of the noise and treat them, we decided to use
convolutional neural network with autoencoder architecture. Taking the recorded
trace as an input, the autoencoder returns denoised trace, i.e. removes all
signal-unrelated amplitudes. We present the comparison between standard method
of signal reconstruction, matched filtering and autoencoder, and discuss the
prospects of application of neural networks for lowering the threshold of
digital antenna arrays for cosmic-ray detection.Comment: ARENA2018 proceeding
The Tunka Experiment: Towards a 1-km^2 Cherenkov EAS Array in the Tunka Valley
The project of an EAS Cherenkov array in the Tunka valley/Siberia with an
area of about 1 km^2 is presented. The new array will have a ten times bigger
area than the existing Tunka-25 array and will permit a detailed study of the
cosmic ray energy spectrum and the mass composition in the energy range from
10^15 to 10^18 eV.Comment: 3 pages, 2 figures, to be published in IJMP
The first experience of low-invasive correction of Pectus Carinatum at children by Abramson procedur
Purpose: justification of relevance of use of a low-invasive method of correction across Abramson
and improvement of treatment of pectus carinatum (PC) at children.
Materials and methods. The result of treatment of 7 boys aged from 12 up to 17 years operated
from 2012 to 2017 concerning PC in MRRCI was analyzed. 4 of them were operated in the open way
on Ravich. A lot of sequels during and after operation led to refusal of open methods of correction of
PC. In the period from 2015 to 2017 three children were operated by Abramson’s method. Dynamometer researches proved the efficiency of Abramson’s method. The multispiral computer tomography
with 3D reconstruction was carried out and allowed to avoid possible intraoperative complications.
During the operation were used epidural and general anesthesia. Allocation of ribs in places of bracing of stabilizers to a periosteum without injury of a pleura allowed to reach the best stability and
reliability of fixatives, reduce a pain syndrome and avoid a possible injury of intrathoracic organs. Epidural anesthesia in combination with analgetics intramusculary provided optimum anesthesia during
the postoperative period. This method leads to faster recovery after operation, 5 days vs 10 days.
Results: the catamnesis collected from 1 month till 2 years is positive. At 1 patient the early postoperative period was complicated by the intense pheumothorax caused by a rupture of a bulla of an
apex of the right lung. The thoracoscopic atypical resection of the violent changed site of a lung is
executed.
Inputs. Using of Abramson’s method allowed to reduce quantity possible intra-and postoperative
complications, achieve amazing cosmetic result and reduce terms of hospitalization by 2,5 times
Current Status and New Challenges of The Tunka Radio Extension
The Tunka Radio Extension (Tunka-Rex) is an antenna array spread over an area
of about 1~km. The array is placed at the Tunka Advanced Instrument for
cosmic rays and Gamma Astronomy (TAIGA) and detects the radio emission of air
showers in the band of 30 to 80~MHz. During the last years it was shown that a
sparse array such as Tunka-Rex is capable of reconstructing the parameters of
the primary particle as accurate as the modern instruments. Based on these
results we continue developing our data analysis. Our next goal is the
reconstruction of cosmic-ray energy spectrum observed only by a radio
instrument. Taking a step towards it, we develop a model of aperture of our
instrument and test it against hybrid TAIGA observations and Monte-Carlo
simulations. In the present work we give an overview of the current status and
results for the last five years of operation of Tunka-Rex and discuss prospects
of the cosmic-ray energy estimation with sparse radio arrays.Comment: Proceedings of E+CRS 201
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