359 research outputs found
On products of skew rotations
Let , be two time-independent Hamiltonians with one
degree of freedom and , be the one-parametric groups of
shifts along the orbits of Hamiltonian systems generated by , . In
some problems of population genetics there appear the transformations of the
plane having the form under some
conditions on , . We study in this paper asymptotical properties of
trajectories of .Comment: 13 pages, 10 figure
Neural network analysis of hyperspectral images of soil
The article approaches to the classification of high-resolution hyperspectral images in the problem of classification of soil species is proposed. A spectral-spatial convolutional neural network with compensation for lighting variations is used as a classifier. The effectiveness of the proposed approach in the problem of classification of hyperspectral images of soils obtained by a scanning hyperspectral camera is shown. The essence of the developed method is to use binary classification together with multiclass, thereby improving the result of the latter
Ferro-Antiferromagnetic Transformation in La0.2Tb0.8Mn2Si2 at Low Temperatures
It is shown that Mn-atom spins transform from ferromagnetic to antiferromagnetic ordering at 48 K
Rigorous Analysis of Singularities and Absence of Analytic Continuation at First Order Phase Transition Points in Lattice Spin Models
We report about two new rigorous results on the non-analytic properties of
thermodynamic potentials at first order phase transition. The first one is
valid for lattice models () with arbitrary finite state space, and
finite-range interactions which have two ground states. Under the only
assumption that the Peierls Condition is satisfied for the ground states and
that the temperature is sufficiently low, we prove that the pressure has no
analytic continuation at the first order phase transition point. The second
result concerns Ising spins with Kac potentials
, where is a small scaling
parameter, and a fixed finite range potential. In this framework, we
relate the non-analytic behaviour of the pressure at the transition point to
the range of interaction, which equals . Our analysis exhibits a
crossover between the non-analytic behaviour of finite range models
() and analyticity in the mean field limit (). In
general, the basic mechanism responsible for the appearance of a singularity
blocking the analytic continuation is that arbitrarily large droplets of the
other phase become stable at the transition point.Comment: 4 pages, 2 figure
Monoclinic form I of clopidogrel hydrogen sulfate from powder diffraction data
The asymmetric unit of the title compound, C16H17ClNO2S+·HSO4
−, (I) [systematic name: (+)-(S)-5-[(2-chlorophenyl)(methoxycarbonyl)methyl]-4,5,6,7-tetrahydrothieno[3,2-c]pyridin-5-ium hydrogen sulfate], contains two independent cations of clopidogrel and two independent hydrogensulfate anions. The two independent cations are of similar conformation; however, this differs from that observed in orthorhombic form (II) [Bousquet et al. (2003 ▶). US Patent No. 6 504 030]. The H—N—Cchiral—H fragment shows a trans conformation in both independent cations in (I) and a gauche conformation in (II). In (I), classical intermolecular N—H⋯O and O—H⋯O hydrogen bonds link two independent cations and two independent anions into an isolated cluster, in which two cations interact with one anion only via N—H⋯O hydrogen bonds. Weak intermolecular C—H⋯O hydrogen bonds further consolidate the crystal packing
Sodium-23 Magnetic Resonance Imaging
23Na MRI provides additional biochemical information to 1H MRI in terms of cell integrity and tissue viability. We aimed at determining the sensitivity of 23Na MRS, MRI and MR relaxometry methods available on 7T MR scanner Bruker Biospec 70/30 USR and developing of an optimal MRI protocol for small animal 23Na in vivo visualization. The outcomes include 23Na MR spectra, 23Na MR images with SNRs, and T1 and T2 values of 23Na. It is shown that single-pulse 23Na MR spectroscopy can discriminate different 23Na concentrations, and 3D FLASH pulse sequence adapted for 23Na data acquisition may provide the acceptable quality images.
Keywords: Sodium MRI, Sodium MRS, 3D FLASH, MR relaxometr
Hyperspectral images neural network analysis of unstained micropreparations
The article presents the results of a study of hyperspectral imaging in microscopy to assess pathological changes in unstained medical micropreparations.Hyperspectral imaging was carried out using a system of synchronous shooting and movement of a movable table combined with a stepper motor. To improve the quality of theobtained images, software correction of the illumination of the spectral channels was used. The classification was carried out by a convolutional neural network. This method may be promising for assessing pathological changes in clinical practice. Experimental studies were carried out on histological preparations with different types of tissues without staining with contrasting medical dyes. To assess the reliability of the classification method, a comparison was made with thestandard method using staining of the studied samples
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