Abstract
In this article, we discuss a new software package of
kinematic and vertex fitting for the CMD-3 experiment at
the VEPP-2000 electron-positron collider. The authors describe in
detail the ...fitting algorithm, parametrization of four-momenta and
trajectories of various particles and present the results of testing
the fitting pakage using events of Monte Carlo simulation of various
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annihilation processes. The authors also provide several
examples of the fitting package validation using Gaussian
simulation. Although the package discussed in this article is
intended for the CMD-3 experiment, it can also be used in
other experiments. The authors consider the described package as
their first step towards a more universal and rigorous kinematic and
vertex fitting package that can be used in future
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experiments, such as the Super Charm-Tau factory.
A
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.
The formation of novel ternary cerium germanide with the chemical composition Ce33.3Ir22.2Ge44.5 (at.%) was established. As derived from powder X-ray diffraction data, the compound crystallizes with ...two polymorphic modifications. The high-temperature modification, established for as-cast alloy, possesses a tetragonal ThSi2-type structure and can be named as Ce(IrxGe1-x)2, x = 0.32. The low-temperature modification forms in the course of heat treatment at 1073 K, crystallizes with an orthorhombic structure of its own type and can be labeled as Ce3Ir2-xGe4+x, x = 0.02. Both structures belong to the AlB2 structural family and are closely related to each other. In both modifications, statistical mixtures of Ir and Ge atoms occupy same crystallographic sites. As found by means of magnetization measurements, the two structural variants of Ce33.3Ir22.2Ge44.5 (at.%) exhibit very similar magnetic properties. Both polymorphs are Curie-Weiss paramagnets with strong crystalline electric field features observed at low temperatures.
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•Two polymorphs were characterized for Ce33.3Ir22.2Ge44.5 (at.%) intermetallic.•ht-Ce(IrxGe1-x)2, x = 0.32, crystallizes with ThSi2 type of structure.•lt-Ce3Ir2-xGe4+x, x = 0.1, crystallizes in the orthorhombic structure of a new type.•Both polymorphs are representatives of the AlB2 structural family.•Both compounds are Curie-Weiss paramagnets with distinct CEF interactions.
In Chirkov et al., (2019), classes of conic and discrete conic functions were introduced. In this paper we use the term convic instead conic. The class of convic functions properly includes the ...classes of convex functions, strictly quasiconvex functions and the class of quasiconvex polynomials. On the other hand, the class of convic functions is properly included in the class of quasiconvex functions. The discrete convic function is a discrete analogue of the convic function. In Chirkov et al., (2019), the lower bound 3n−1log(2ρ−1) for the number of calls to the comparison oracle needed to find the minimum of the discrete convic function defined on integer points of some n-dimensional ball with radius ρ was obtained. But the problem of the existence of a polynomial (in logρ for fixed n) algorithm for minimizing such functions has remained open. In this paper, we answer positively the question of the existence of such an algorithm. Namely, we propose an algorithm for minimizing discrete convic functions that uses 2O(n2logn)logρ calls to the comparison oracle and has 2O(n2logn)poly(logρ) bit complexity.
We studied various aspects of heat‐shock response with special emphasis on the expression of heat‐shock protein 70 (hsp70) genes at various levels in two congener species of littoral endemic ...amphipods (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal which show striking differences in their vertical distribution and thermal tolerance. Although both the species studied demonstrate high constitutive levels of Hsp70, the thermotolerant E. cyaneus exhibited a 5‐fold higher basal level of Hsp70 proteins under normal physiological conditions (7 °C) and significantly lower induction of Hsp70 after temperature elevation compared with the more thermosensitive E. verrucosus. We isolated the hsp70 genes from both species and analysed their sequences. Two isoforms of the cytosolic Hsp70/Hsc70 proteins were detected in both species under normal physiological conditions and encoded by two distinct hsp/hsc70 family members. While both Hsp70 isoforms were synthesized without heat shock, only one of them was induced by temperature elevation. The observed differences in the Hsp70 expression patterns, including the dynamics of Hsp70 synthesis and threshold of induction, suggest that the increased thermotolerance in E. cyaneus (compared with E. verrucosus) is associated with a complex structural and functional rearrangement of the hsp70 gene family and favoured the involvement of Hsp70 in adaptation to fluctuating thermal conditions. This study provides insights into the molecular mechanisms underlying the thermal adaptation of Baikal amphipods and represents the first report describing the structure and function of the hsp70 genes of endemic Baikal species dwelling in thermally contrasting habitats.
Lake Baikal is inhabited by more than 300 endemic amphipod species, which are narrowly adapted to certain thermal niches due to the high interspecific competition. In contrast, the surrounding ...freshwater fauna is commonly represented by species with large-scale distribution and high phenotypic thermal plasticity. Here, we investigated the thermal plasticity of the energy metabolism in two closely-related endemic amphipod species from Lake Baikal (Eulimnogammarus verrucosus; stenothermal and Eulimnogammarus cyaneus; eurythermal) and the ubiquitous Holarctic amphipod Gammarus lacustris (eurythermal) by exposure to a summer warming scenario (6-23.6 °C; 0.8 °C d
). In concert with routine metabolic rates, activities of key metabolic enzymes increased strongly with temperature up to 15 °C in E. verrucosus, whereupon they leveled off (except for lactate dehydrogenase). In contrast, exponential increases were seen in E. cyaneus and G. lacustris throughout the thermal trial (Q
-values: 1.6-3.7). Cytochrome-c-oxidase, lactate dehydrogenase, and 3-hydroxyacyl-CoA dehydrogenase activities were found to be higher in G. lacustris than in E. cyaneus, especially at the highest experimental temperature (23.6 °C). Decreasing gene expression levels revealed some thermal compensation in E. cyaneus but not in G. lacustris. In all species, shifts in enzyme activities favored glycolytic energy generation in the warmth. The congruent temperature-dependencies of enzyme activities and routine metabolism in E. verrucosus indicate a strong feedback-regulation of enzymatic activities by whole organism responses. The species-specific thermal reaction norms reflect the different ecological niches, including the spatial distribution, distinct thermal behavior such as temperature-dependent migration, movement activity, and mating season.
The metamagnetic transition in cerium-based intermetallics is a very common intriguing phenomenon that has remained the subject of close study for several decades. We report crystal structure, ...magnetization and resistivity of a new ternary cerium germanide Ce3Pd2Ge7 with an orthorhombic structure of La3Co2Sn7-type (space group Cmmm, cell dimensions a = 4.3257(3), b = 26.339(2), c = 4.3594(3) Å, V = 496.69(2) Å3). Low-temperature magnetic properties are characterized by a two-step metamagnetic transition, which can be associated with two nonequivalent positions of Ce ions in the lattice. The first metamagnetic transition occurs in weak magnetic fields below T1 ≈ 11 K and then moves to higher fields when the temperature goes down (B ∼ 1.5 T at T = 2 K). The second transition manifests itself below T2 ≈ 8 K as a rapid increase of magnetization, which starts from zero field and reaches saturation at fields B ≈ 0.1 T. The magnitude of each transition increases with decreasing temperature and the polarized magnetization ΔM reaches 0.13 μB/Ce and 0.08 μB/Ce upon the first and second transitions respectively. The interchange of nonmagnetic Pd and Ge ions (≈ 0.8 %) leads to the appearance of a hysteresis of metamagnetic transitions, as well as to the splitting of the field cooled (FC) and zero field cooled (ZFC) magnetization curves in hysteresis area. The dependence of the polarized magnetization ΔM on temperature which persists up to high fields as well as the continuation of the hysteresis well above the metamagnetic transition (at least up to B ∼ 9 T) indicates a new type of spin-glass-like state, which is caused by the suppression of spin fluctuations and the localization of magnetic moments during the metamagnetic transition.
•-Synthesis and crystal structure analysis of a new ternary cerium intermetallide.•-Magnetic properties are caused by metamagnetic transitions on nonequivalent Ce ions.•-Metamagnetic transition is caused by suppression of Kondo spin fluctuations.•-Non-magnetic atomic disorder causes spin-glass state with hysteresis behavior.
Actinobacteria from terrestrial and marine environments produce a variety of natural products that mediate inter- and intraspecies interactions. In contrast, the potential of freshwater ...Actinobacteria for secondary metabolite production remains underexplored. Large lakes with a long evolutionary history might contain microflora subjected to unique environmental conditions that favor the evolution of unique metabolic capabilities. One such lake is Lake Baikal (Russia), the deepest lake on earth as well as one of the oldest. In this study, we investigated the genetically encoded secondary metabolic potential of 24 Actinobacteria strains isolated from Lake Baikal sediments. PCR-based screening for genes encoding type I and type II polyketide synthases (PKSs), nonribosomal peptide synthetases (NRPSs), and halogenases confirmed that all strains possessed at least 1 of these biosynthetic genes. Both PKSs and NRPSs were widely distributed, while halogenase-encoding genes were not detected. Phylogenetic comparison of type I PKS ketosynthase (KS) domain sequences between freshwater isolates and marine and terrestrial strains supported overlap between KSs from these 3 groups. Evaluation of antibiotic activity for chemical extracts from all isolates revealed that 75% produced metabolites inhibitory toward model bacteria and/or fungi. To our knowledge, this study is among the first evaluations of the genetically encoded secondary metabolic capabilities of freshwater sediment Actinobacteria. Our findings highlight the similarities and differences between freshwater and marine Actinobacteria secondary metabolism, suggesting the potential of freshwater Actinobacteria for the production of natural products that may play roles as mediators of interactions between organisms in freshwater habitats.
An efficient method for the selective preparation of trifluoromethyl-substituted azepin-2-carboxylates and their phosphorous analogues has been developed via Cu(I)-catalyzed tandem ...amination/cyclization reaction of functionalized allenynes with primary and secondary amines.
A new type of eight-membered ring N-heterocyclic carbene (NHC) bearing a rigid naphthalene moiety in the backbone is reported for the first time. Stereoelectronic properties of ...4,5-dihydro-1H-naphtho1,8-ef1,3diazocin-3(2H)-ylidene (NaphtDHD) and smaller ring NHCs were theoretically studied at the DFT level. Amidinium salts were prepared from corresponding amidines and dibromides. Free carbene NaphtDHD-Dipp (Dipp = 2,6-diisopropylphenyl) was generated in solution by treatment of the corresponding salt with LiHMDS. It is stable in solution at low temperatures, while decomposing rapidly at room temperature. Silver(i) and copper(i) complexes were synthesized and structurally characterized in the solid state. The copper(i) complex (NaphtDHD-Mes)CuBr (Mes = mesityl, 2,4,6-trimethylphenyl) exhibits high catalytic activity in alkyne-azide cycloaddition (CuAAC) reaction under solvent-free conditions.
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