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bstract
In this paper, we propose a new method for obtaining a Born cross section using visible cross section data. It is assumed that the initial state radiation is taken into account in a visible ...cross section, while in a Born cross section this effect is ommited. Since the equation that connects Born and visible cross sections is an integral equation of the first kind, the problem of finding its numerical solution is ill-posed. Various regularization-based approaches are often used to solve ill-posed problems, since direct methods usually do not lead to an acceptable result. However, in this paper it is shown that a direct method can be successfully used to numerically solve the considered equation under the condition of a small beam energy spread and uncertainty. This naive method is based on finding a numerical solution to the integral equation by reducing it to a system of linear equations. The naive method works well because the kernel of the integral operator is a rapidly decreasing function of the variable
x
. This property of the kernel leads to the fact that the condition number of the matrix of the system of linear equations is of the order of unity, which makes it possible to neglect the ill-posedness of the problem when the above condition is satisfied. The advantages of the naive method are its model independence and the possibility of obtaining the covariance matrix of a Born cross section in a simple way.
It should be noted that there are already a number of methods for obtaining a Born cross section using visible cross section data, which are commonly used in
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experiments. However, at least some of these methods have various disadvantages, such as model dependence and relative complexity of obtaining a Born cross section covariance matrix. It should be noted that this paper focuses on the naive method, while conventional methods are hardly covered. The paper also discusses solving the problem using the Tikhonov regularization, so that the reader can better understand the difference between regularized and non-regularized solutions. However, it should be noted that, in contrast to the naive method, regularization methods can hardly be used for precise obtaining of a Born cross section. The reason is that the regularized solution is biased and the covariance matrix of this solution do not represent the correct covariance matrix of a Born cross section.
Recent advances in DNA sequencing open prospects to make whole-genome analysis rapid and reliable, which is promising for various applications including personalized medicine. However, existing ...techniques for de novo genome assembly, which is used for the analysis of genomic rearrangements, chromosome phasing, and reconstructing genomes without a reference, require solving tasks of high computational complexity. Here we demonstrate a method for solving genome assembly tasks with the use of quantum and quantum-inspired optimization techniques. Within this method, we present experimental results on genome assembly using quantum annealers both for simulated data and the Formula: see textX 174 bacteriophage. Our results pave a way for a significant increase in the efficiency of solving bioinformatics problems with the use of quantum computing technologies and, in particular, quantum annealing might be an effective method. We expect that the new generation of quantum annealing devices would outperform existing techniques for de novo genome assembly. To the best of our knowledge, this is the first experimental study of de novo genome assembly problems both for real and synthetic data on quantum annealing devices and quantum-inspired techniques.
•We showed how the magnetic field of non-uniform waveguide influences for 3D crystals.•Explored conditions for forward and backward spin waves existence in meander profile.•Comparison dispersion ...patterns for surface and bulk modes in 3D magnonic crystal.
We present three-dimensional (3D) model of periodic meander-shaped ferromagnetic films. Spin wave propagation in such films and vertically coupled structures was studied using micromagnetic modeling and theoretical plane wave method. Spin waves in these structures essentially propagate in film’s segments located at right angles with respect to each other. This makes really possible for the wave to propagate in three dimensions. We calculated internal effective magnetic fields and obtained spin wave dispersion in single and vertically coupled structures. Additionally, comparison of surface and volume spin waves propagation in such meander films was provided. Our results can be useful for magnonic logic elements development.
A process of searching on the sphere for the best (in a sense) cubature formulas that are invariant under the transformations of the icosahedral rotation group is described. The parameters of the ...best cubature formulas of this symmetry type up to the 30th order of accuracy are given to 16 significant digits. A table which contains the main characteristics of all the best to date cubature formulas of the icosahedral rotation group up to the 79th order of accuracy is given.
•Heat transfer enhancement by inclined trenches in the micro-channel is considered.•Significant laminar separation flow augmentation in the oval trench is obtained.•Maximum secondary flow velocity ...reaches a value of 0.72 of bulk velocity.•Mechanism of flow and heat transfer enhancement by inclined trenches is discovered.•The thermal performance of the dimpled portion has a value of 1.8.•The inclined trench depth optimal in Thermal Heat Performance is equal to 0.25.
Enhancement of heat transfer in laminar air flow in narrow channels, whose walls are provided with regularly spaced single-row inclined oval-trench dimples, is associated with designing mini- and micro-channels of microelectronics cooling devices, compact miniature heat exchangers, air capacitors, radiators. Vortex heat transfer is considered using the computational domain of the narrow micro-channel of dimensionless height 1, width 6 and length 4 at periodic boundary conditions. An oval-trench dimple of dimensionless width 1 and length 4.5 is located in the center of the heated wall at an angle of 45° to incoming flow. To solve the Navier–Stokes equations and the energy equation, multiblock computational technique realized in the VP2/3 code on overlapping grids of different topology and with a different density of computational cells has found use. The Reynolds number is equal to 103. The dimple depth Δ is varied from 0 to 0.375. Dimples are classified: shallow dimples and dimples of moderate and large depth. As Δ is increased, substantial laminar separated flow augmentation on the entrance portion of the inclined dimple is revealed and explained. Maximum absolute value of relative friction at Δ = 0.375 is twice increased in comparison to this quantity at Δ = 0.1125–0.25. A maximum absolute value of the secondary flow velocity in the dimple reaches 0.72 of bulk velocity. In the case of single-row inclined oval-trench dimples with a depth of more than 0.25, in the narrow channel the phenomenon of laminar flow acceleration with a 1.5-fold growth of a maximum core velocity is discovered. It is established that a reason for laminar separated and secondary flow augmentation in the inclined oval-trench dimple lies in a sharp static pressure drop (maximum pressure value is 0.34 and minimum pressure value is −0.14 at Δ = 0.3125) at a very small distance between the centers of high and low pressure zones on the entrance portion of the dimple. By increasing Δ, local relative heat loads on the entrance portion of the dimple on the windward side grow and reach values of 16–17. Maximum thermal performance determined by relative total Nusselt numbers averaged over a streamlined wall section with an inclined dimple is 1.8 at Δ = 0.3125; maximum thermal-hydraulic performance is 1.3 at Δ = 0.25.
Photometric measurements are prone to systematic errors presenting a challenge to low-amplitude variability detection. In search for a general-purpose variability detection technique able to recover ...a broad range of variability types including currently unknown ones, we test 18 statistical characteristics quantifying scatter and/or correlation between brightness measurements. We compare their performance in identifying variable objects in seven time series data sets obtained with telescopes ranging in size from a telephoto lens to 1 m-class and probing variability on time-scales from minutes to decades. The test data sets together include light curves of 127 539 objects, among them 1251 variable stars of various types and represent a range of observing conditions often found in ground-based variability surveys. The real data are complemented by simulations. We propose a combination of two indices that together recover a broad range of variability types from photometric data characterized by a wide variety of sampling patterns, photometric accuracies and percentages of outlier measurements. The first index is the interquartile range (IQR) of magnitude measurements, sensitive to variability irrespective of a time-scale and resistant to outliers. It can be complemented by the ratio of the light-curve variance to the mean square successive difference, 1/..., which is efficient in detecting variability on time-scales longer than the typical time interval between observations. Variable objects have larger 1/... and/or IQR values than non-variable objects of similar brightness. Another approach to variability detection is to combine many variability indices using principal component analysis. We present 124 previously unknown variable stars found in the test data. (ProQuest: ... denotes formulae/symbols omitted.)
Herein we report the study of the influence of synthesis conditions during the microwave-hydrothermal crystallization of freshly precipitated gels on the phase composition and morphology of the ...rare-earth doped yttrium orthophosphates nanoparticles. We characterize the nanoparticles of YPO sub(4) and YPO sub(4) times 0.8H sub(2)O using X-ray diffraction analysis, TEM, and FT-IR spectroscopy. Furthermore, we argue that for the given phase the degree of crystallinity and thus the sample morphology depend strongly on the synthesis conditions. We establish that the hexagonal hydrate phase can be obtained by means of microwave-hydrothermal method if one uses phosphate anion excess or adjusts pH of the reaction mixture. Also we show that the metastable hydrate phase is most likely stabilized by hydroxyl groups at elevated temperatures.
The Russian Federation is one of many countries that have signed the Montreal Protocol and Pan-European Forest Process. These initiatives are aimed at harmonizing national forest inventory systems ...with criteria and indicators for sustainable forest management. In Russia, the classification of forest type is at the heart of national forest inventory systems. For various historical reasons, Russian scientific advancements in the field of forest typology remain little known in the rest of the world. This paper is aimed at addressing this deficiency. Here, we provide an overview of the main trends in the field of forest typology studies in the previous political states of the Russian Empire, the Soviet Union, and the Russian Federation from the end of the nineteenth century to the beginning of the twenty-first century. We detail the principles that formed the basis of the most significant forest type classifications. We also perform similarity and differences analyses comparing approaches used by members of different scientific schools in the field of forest typology. The historical relationship between ecological, phytocoenotic, genetic, and dynamic forest type classifications are discussed as well as the reasons for the prevalence of certain forest type classifications in different regions of Russia.
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