1,887 research outputs found
Historic responsibility in terms of intergenerational relations
This article based on an analysis of the theoretical problems of historical events and historical memory discusses the results of the sociological research students on the problems of historical memory of the great patriotic war, identifies "gaps" and deformation in this memory.В статье на основе анализа теоретических проблем исторического события и исторической памяти рассматриваются результаты социологических исследований студенческой молодежи по проблемам исторической памяти о Великой Отечественной войне, выявляются «пробелы» и деформации в этой памяти
Low pressure gas electron diffraction: An experimental setup and case studies.
Vishnevskiy Y, Blomeyer S, Reuter C. Low pressure gas electron diffraction: An experimental setup and case studies. The Review of scientific instruments. 2020;91(7): 074104.Principles of low pressure gas electron diffraction are introduced. An experimental setup has been constructed for measuring the electron diffraction patterns of gaseous samples at pressures below 10-3 mbar. Test measurements have been performed for benzoic acid at T = 287 K corresponding to a vapor pressure of the substance P = 2 * 10-4 mbar, for iodoform CHI3 at T = 288 K (P = 4 * 10-4 mbar), and for carbon tetraiodide CI4 at T = 290 K (P = 1 * 10-4 mbar). Due to the low experimental temperature, thermal decomposition of CI4 has been prevented, which was unavoidable in previous classical measurements at higher temperatures. From the obtained data, the molecular structures have been successfully refined. The most important semi-empirical equilibrium molecular parameters are re(Car-Car)av = 1.387(5) A in benzoic acid, re(C-I) = 2.123(3) A in iodoform, and re(C-I) = 2.133(7) A in carbon tetraiodide. The determined parameters showed consistency with the theoretically predicted values. A critical comparison with the results of the earlier investigations has also been done
Implicit Modeling with Uncertainty Estimation for Intravoxel Incoherent Motion Imaging
Intravoxel incoherent motion (IVIM) imaging allows contrast-agent free in
vivo perfusion quantification with magnetic resonance imaging (MRI). However,
its use is limited by typically low accuracy due to low signal-to-noise ratio
(SNR) at large gradient encoding magnitudes as well as dephasing artefacts
caused by subject motion, which is particularly challenging in fetal MRI. To
mitigate this problem, we propose an implicit IVIM signal acquisition model
with which we learn full posterior distribution of perfusion parameters using
artificial neural networks. This posterior then encapsulates the uncertainty of
the inferred parameter estimates, which we validate herein via numerical
experiments with rejection-based Bayesian sampling. Compared to
state-of-the-art IVIM estimation method of segmented least-squares fitting, our
proposed approach improves parameter estimation accuracy by 65% on synthetic
anisotropic perfusion data. On paired rescans of in vivo fetal MRI, our method
increases repeatability of parameter estimation in placenta by 46%
CMS HCAL Installation and Commissioning
The installation and commissioning of the Hadron Calorimeter system of the CMS detector is described and the performance of the various monitoring systems, the progress in the calibration work and the current plans for the HCAL calorimeter are summarized
Ultrasound Aberration Correction based on Local Speed-of-Sound Map Estimation
For beamforming ultrasound (US) signals, typically a spatially constant
speed-of-sound (SoS) is assumed to calculate delays. As SoS in tissue may vary
relatively largely, this approximation may cause wavefront aberrations, thus
degrading effective imaging resolution. In the literature, corrections have
been proposed based on unidirectional SoS estimation or
computationally-expensive a posteriori phase rectification. In this paper we
demonstrate a direct delay correction approach for US beamforming, by
leveraging 2D spatial SoS distribution estimates from plane-wave imaging. We
show both in simulations and with ex vivo measurements that resolutions close
to the wavelength limit can be achieved using our proposed local SoS-adaptive
beamforming, yielding a lateral resolution improvement of 22% to 29% on tissue
samples with up to 3% SoS-contrast (45m/s). We verify that our method
accurately images absolute positions of tissue structures down to sub-pixel
resolution of a tenth of a wavelength, whereas a global SoS assumption leads to
artifactual localizations.Comment: will be published in the proceedings of the IEEE International
Ultrasonics Symposium (IUS) 201
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