Benchmarking nuclear models for Gamow-Teller response

A comparative study of the nuclear Gamow-Teller response (GTR) within conceptually different state-of-the-art approaches is presented. Three nuclear microscopic models are considered: (i) the recently developed charge-exchange relativistic time blocking approximation (RTBA) based on the covariant density functional theory, (ii) the shell model (SM) with an extended "jj77" model space and (iii) the non-relativistic quasiparticle random-phase approximation (QRPA) with a Brueckner G-matrix effective interaction. We study the physics cases where two or all three of these models can be applied. The Gamow-Teller response functions are calculated for 208-Pb, 132-Sn and 78-Ni within both RTBA and QRPA. The strengths obtained for 208-Pb are compared to data that enables a firm model benchmarking. For the nucleus 132-Sn, also SM calculations are performed within the model space truncated at the level of a particle-hole (ph) coupled to vibration configurations. This allows a consistent comparison to the RTBA where ph+phonon coupling is responsible for the spreading width and considerable quenching of the GTR. Differences between the models and perspectives of their future developments are discussed.Comment: 9 pages, 2 figures, 1 table; to be published in Phys. Lett.

Electronic hybridization effects in dense intermetallics measured by electron spin resonance

Recent theoretical studies associate the unexpected well resolved electron spin resonance (ESR) signals below Kondo temperature in several undoped heavy-fermion (HF) compounds with hybridization effects between 4f and conduction electrons (CE) in the presence of ferromagnetic (FM) fluctuations. We analyze ESR experiments in different concentrated Yb-, Ce-, and Eu-based intermetallic systems. We believe that the exotic ESR absorption here is caused by a novel type of ESR excitations - hybridized electronic states, which can be created in some strongly correlated electronic systems due to hybridization between the 4f-orbitals and the wave functions of the CE of the outer electronic shells in conjunction with FM RKKY interaction. © Published under licence by IOP Publishing Ltd

Gender Factor in Associative Links of Words: Dictionary and Distributive-Semantic Model Data

The aim of the work is to make a comparative analysis of the associative links of full-meaning words from the upper zone of the frequency list, compiled on the basis of a research corpus of blog texts in Russian, in a psycholinguistic experiment and the distributivesemantic model Global Vectors (GloVe), trained on this corpus. The relevance of the work is due to the need for a comprehensive study of the psychologically relevant meaning of the word. The novelty of the study lies in the fact that such an analysis is carried out taking into account the gender factor of the respondent / author of the text. The use of a set of methods for data mining (clustering, classification) and visualization of its results made it possible to establish the influence of gender on the composition of the semantic associates of the analyzed words (that is, words with close vectors in the distributive-semantic model) and the absence of such an effect in their associates recorded in the associative dictionary. As the study showed, distributivesemantic models and dictionary associative norms reflect different aspects of the psychologically relevant content of the word and should be used as complementary sources when modeling the psychologically relevant meaning of the word, taking into account the individual characteristics of the speaker, while conducting such an analysis it is advisable to use data mining methods

Fixed nitrogen in agriculture and its role in agrocenoses

Received: February 23rd, 2021 ; Accepted: May 12th, 2021 ; Published: May 19th, 2021 ; Correspondence: [email protected] typical low-humus black soils in short crop rotations with legumes (25–33%) and without them, it was found that depending on the set of crops in crop rotation and application of fertilizer rates, nitrogen yield per crop is from 355 kg ha-1 to 682 kg ha-1 . The recommended fertilization system provided nitrogen compensation for crop yields by only 31–76%. Hence, in the plant-fertilizer system nitrogen deficiency varies from 161 to 370 kg ha-1 . The greatest nitrogen deficiency in the soil is observed in crop rotation without the use of fertilizers with the following crop rotation: peas-winter wheat-grain maize-spring barley. The main source of nitrogen for plants is soil nitrogen. In crop rotations with legumes, biological nitrogen is supplied from the air, which in quantitative terms per rotation in crop rotations with peas is 109–288 kg ha-1 , with soybeans 264–312, and with alfalfa 486 kg ha-1 . Biological nitrogen in crop rotations with peas and soybeans is reimbursed from 25 to 62%, in crop rotation without legumes - 9% (non-symbiotic nitrogen fixation), and in crop rotation with alfalfa - 89% of the total nitrogen removal with the crop

Electron spin resonance in the Heusler alloy YbRh2Pb

An electron spin resonance (ESR) signal was observed in a concentrated Kondo lattice, Heusler alloy YbRh2Pb. It is attributed to the combined effect of the 4f local magnetic moments of Yb3+ and conduction electrons. It is shown that the significant broadening and disappearance of the ESR line at temperatures above 20 K is caused by the processes of the spin-lattice relaxation of the Yb3+ ions through the first excited Stark doublet with an activation energy Δ ≈ 73.5 K. A comparison of the ESR data for YbRh2Pb and some other undoped intermetallic compounds based on ytterbium, cerium, and europium indicates that hybridized electronic states occurring as the result of hybridization between the localized 4f electrons and the collectivized conduction electrons constitute a fundamentally new source of ESR. © Pleiades Publishing, Ltd., 2009

Hybridized electronic states in dense intermetallics as studied by ESR

We review electron spin resonance (ESR) experiments in several concentrated Yb-, Ce-, and Eubased intermetallic systems. Recent theoretical studies attribute well resolved ESR signals with hybridization effects between 4f and conduction electrons (CE) in the presence of ferromagnetic (FM) fluctuations. We believe that the ESR absorption is caused here by a novel type of ESR excitations - hybridized electronic states, which are created in some strongly correlated electronic systems due to hybridization between the 4f-orbitals and the wavefunctions of the CE of the outer d, s, and p shells in conjunction with FM RKKY interaction. © (2011) Trans Tech Publications

Modern Physicochemical Equilibrium Description in Na2O–Al2O3–H2O System and Its Analogues

Equilibrium and non-equilibrium states of systems Na2O–Al2O3–H2O and K2O–Al2O3–H2O are crucial for establishing key technological parameters in alumina production and their optimization. Due to a noticeable discrepancy between experimental results and thermodynamic calculations based on materials of individual researchers the necessity of systematization and statistical processing of equilibrium data in these systems to create a reliable base of their physicochemical state, analysis and mathematical modeling of phase equilibria is substantiated. The tendency to a decrease of the hydration degree of solid sodium aluminates with increasing temperature and the transition of systems from the steady state of gibbsite to equilibrium with boehmite is revealed. The paper contains approximating functions that provide high-precision description of equilibrium isotherms in technologically significant area of Na2O–Al2O3–H2O and K2O–Al2O3–H2O concentrations. Approximating function can be simplified by dividing the isotherm into two sections with the intervals of alkaline content 0-0.25 and 0.25-0.4 mole/100 g of solution. The differences in solubility isotherms for Na2O–Al2O3–H2O and K2O–Al2O3–H2O systems provide are associated with changes in the ionic composition solutions that depends on concentration and temperature, as well as differences connecting with alkali cation hydration, which is crucially important for thermodynamic modeling of equilibria under consideration