Resource
2018 EN
O. S. Deiev · V. N. Dubina · S. K. Kiprich
+3 more
The thermal neutrons were registered using a two-detector module based on twoplanar Si detectors: with a neutron converter from natural metallic Gd andwithout a converter. To obtain thermal neutrons we used a 239Pu-Be({\alpha},n)fast neutron source with a paraffin moderator. The measurements were carriedout simultaneously by two detectors by processing two channels of registrationwith a special computer program. In experiments gamma radiation was notsuppressed. The conversion electrons of the nuclear reaction Gd(n,{\gamma}e)Gdwere registered. We performed the registration of thermal neutrons with thepossibility of subtraction for background radiation.
Resource
2018 EN
Dimitri Polyakov · Cong Zhang
We determine the form of a significantly large class of gauge-invariantquartic vertices for symmetric higher-spin fields (in Vasiliev formalism) inAdS5 space in the rectangular limit, (defined in the paper) using thehigher-spin vertex operators in superstring theory, which construction is basedon the generators of the higher-spin symmetry algebra, enveloping the AdSisometries. In this limit, a particular simplification is that the quarticvertices do not receive corrections from worldsheet renormalization group flowsof the cubic terms, so their structure is fixed directly by the 4-pointamplitudes in superstring theory.
Resource
2018 EN
Dmitry Lachinov · Evgeny Vasiliev · Vadim Turlapov
MRI analysis takes central position in brain tumor diagnosis and treatment,thus it's precise evaluation is crucially important. However, it's 3D natureimposes several challenges, so the analysis is often performed on 2Dprojections that reduces the complexity, but increases bias. On the other hand,time consuming 3D evaluation, like, segmentation, is able to provide preciseestimation of a number of valuable spatial characteristics, giving usunderstanding about the course of the disease.\newline Recent studies, focusingon the segmentation task, report superior performance of Deep Learning methodscompared to classical computer vision algorithms. But still, it remains achallenging problem. In this paper we present deep cascaded approach forautomatic brain tumor segmentation. Similar to recent methods for objectdetection, our implementation is based on neural networks; we proposemodifications to the 3D UNet architecture and augmentation strategy toefficiently handle multimodal MRI input, besides this we introduce approach toenhance segmentation quality with context obtained from models of the sametopology operating on downscaled data. We evaluate presented approach on BraTS2018 dataset and discuss results.
Resource
2018 EN
STAR Collaboration · J. Adam · L. Adamczyk
+350 more
We report systematic measurements of dielectron ($e^{\pm}e^{\pm}$)invariant-mass $M_{ee}$ spectra at mid-rapidity in Au+Au collisions at$\sqrt{s_{NN}}$ = 27, 39, and 62.4 GeV taken with the STAR detector at theRelativistic Heavy Ion Collider. For all energies studied, a significant excessyield of dielectrons is observed in the low-mass region (0.40$ < M_{ee} < 0.75$MeV/$c^2$) compared to hadronic cocktail simulations at freeze-out. Models thatinclude an in-medium broadening of the $\rho$-meson spectral functionconsistently describe the observed excess. In addition, we reportacceptance-corrected dielectron-excess spectra for Au+Au collisions atmid-rapidity ($\left|y_{ee}\right|$ $<$ 1) in the 0$-$80% centrality bin foreach collision energy. The integrated excess yields for $0.4 < M_{ee} < 0.75\\textrm{GeV}/c^{2}$, normalized by the charged particle multiplicity atmid-rapidity, are compared with previously published measurements for Au+Au at$\sqrt{s_{NN}}$ = 19.6 and 200 GeV. The normalized excess yields in thelow-mass region show no significant collision energy dependence. The data,however, are consistent with model calculations that demonstrate a modestenergy dependence.
Journals
2017 EN
Kazin Pavel E. · Zykin Mikhail A. · Utochnikova Valentina V.
+6 more
Meeting the challenges of Moore's Law, predicting ambitious miniaturization rates of integrated circuits, requires to go beyond the traditional top‐down approaches, and to employ synthetic chemistry methods, to use bottom‐up techniques. During the recent decades, it has been shown that open‐shell coordination compounds may exhibit intramolecular spontaneous magnetization, thus offering promising prospects for storage and processing of digital information. Against this background we regarded it rewarding to implement similar magnetic centers into a ceramic material, which would provide better long‐term mechanical and chemical durability. Here we present new robust inorganic compounds containing separate DyO + ions in an apatite matrix, which behave like single‐molecule magnets. The materials exhibit a blocking temperature of 11 K and an energy barrier for spin reversal of a thousand inverse centimeters which is among the highest values ever achieved.
Journals
2017 EN
Kazin Pavel E. · Zykin Mikhail A. · Utochnikova Valentina V.
+6 more
Meeting the challenges of Moore's Law, predicting ambitious miniaturization rates of integrated circuits, requires to go beyond the traditional top‐down approaches, and to employ synthetic chemistry methods, to use bottom‐up techniques. During the recent decades, it has been shown that open‐shell coordination compounds may exhibit intramolecular spontaneous magnetization, thus offering promising prospects for storage and processing of digital information. Against this background we regarded it rewarding to implement similar magnetic centers into a ceramic material, which would provide better long‐term mechanical and chemical durability. Here we present new robust inorganic compounds containing separate DyO + ions in an apatite matrix, which behave like single‐molecule magnets. The materials exhibit a blocking temperature of 11 K and an energy barrier for spin reversal of a thousand inverse centimeters which is among the highest values ever achieved.
Journals
2017 EN
Plokhikh Aleksandr V. · Falmbigl Matthias · Golovina Iryna S.
+5 more
We report on the growth of polycrystalline BiFeO 3 thin films on SiO 2 /Si(001) and Pt(111) substrates by atomic layer deposition using the precursors ferrocene, triphenyl‐bismuth, and ozone. By growing alternating layers of Fe 2 O 3 and Bi 2 O 3 , we employ a superlattice approach and demonstrate an efficient control of the cation stoichiometry. The superlattice decay and the resulting formation of polycrystalline BiFeO 3 films are studied by in situ X‐ray diffraction, in situ X‐ray photoelectron spectroscopy, and transmission electron microscopy. No intermediate ternary phases are formed and BiFeO 3 crystallization is initiated in the Bi 2 O 3 layers at 450 °C following the diffusion‐driven intermixing of the cations. Our study of the BiFeO 3 formation provides an insight into the complex interplay between microstructural evolution, grain growth, and bismuth oxide evaporation, with implications for optimization of ferroelectric properties.
Journals
2017 EN
Danilovich Igor L. · Karpova Elena V. · Morozov Igor V.
+6 more
The copper salt of trifluoroacetic acid, Cu(CF 3 COO) 2 , offers a new platform to investigate the quantum ground states of low‐dimensional magnets. In practice, it realizes the ideal case of a solid hosting essentially isolated magnetic monolayers. These entities are constituted by well‐separated two‐leg half‐integer spin ladders organized in a zigzag fashion. The ladders are comprised of dimeric units of edge‐sharing tetragonal pyramids coupled through carbon ions. The spin‐gap state in this compound was revealed by static and dynamic magnetic measurements. No indications of long range magnetic ordering down to liquid helium temperature were obtained in specific heat measurements. First principles calculations allow estimation of the main exchange interaction parameters, J ⊥ =176 K and J ∥ =12 K, consistent with the weakly interacting dimers model.
Journals
2017 EN
Plokhikh Aleksandr V. · Falmbigl Matthias · Golovina Iryna S.
+5 more
The Back Cover picture illustrates the formation of the complex multiferroic oxide BiFeO 3 from an atomic layer deposition grown superlattice of alternating Fe 2 O 3 and Bi 2 O 3 layers. The as‐grown superlattice serves as a diffusion couple on the nanoscale and permits insights into the diffusion and reaction mechanisms involved in the formation of a complex oxide (Image: Ella Maru Studio). More information can be found in the Communication by J. E. Spanier and co‐workers on page 1965 in Issue 15, 2017 (DOI: 10.1002/cphc.201700407).
Journals
2017 EN
Soloviev Arcady Nikolaevich · Sobol Boris Vladimirovich · Rashidova Elena Viktorovna
+1 more
The problem of plane deformation of the elastic ring with an inner radial cut is considered. On the inner edge of the ring hydrostatic pressure affected. The outer boundary is reinforced with a thin flexible coating, the outer boundary of it is free. As a coating model used special boundary conditions are formulated on the basis of the asymptotic analysis of the exact solution of the elasticity problem for the ring. It is difficult to find a range of geometrical and physical parameters of the problem analytically. That's why a series of numerical experiments using FEM package carried out. In particular, it was found that the error of the accepted model increases with the coating hardness and thickness. Discontinuous solution method technology in the Fourier series implemented. The boundary conditions on the crack faces satisfied. As a result of summation of series, the problem reduces to the solution of a singular integral equation for the derivative crack expanding function. The singular part is a Cauchy kernel and corresponds to the limiting classical case. A regular part of the kernel depends on the geometrical and physical parameters of the problem. The convergence of the obtained series investigated. The solution of the integral equation is constructed by collocation method as a linear combination of basis functions. Of course we taking into account the characteristic peaks in the vicinity of the crack. A first kind Chebyshev polynomials are used. Reduced stress intensity factor as an influence factor established. Qualitative and quantitative features of effect of the material and coating thickness on the intensity of the stresses in the vicinity of the crack tip established.