207Pb and 17O NMR Study of the Electron Density Distribution in Metal Phase of BaPb_{1-x}Bi_xO_3

The 17O and 207Pb NMR spectra were measured in ceramic samples in the metallic phase of BaPb_{1-x}Bi_{x}O_3 oxides (0<x< 0.33). The inhomogeneous magnetic broadening which appears due to a distribution of the Knight shifts was analyzed in detail. It is shown that Bi atoms, which are randomly incorporated in BaPbO_3 parent compound give rise to an increased conduction electron spin density within an area which is delimited by its two first cation shells. According to NMR data the percolative overlap of these areas occurs in superconducting compositions and it is accompanied by a sharp growth of the average Knight shift . The decrease of with temperature revealed for x=0.33 evidences for an opening of the energy gap near E_F near the metal-semiconductor transition (x=0.35).Comment: submitted to Phys. Rev.

Differential elimination for dynamical models via projections with applications to structural identifiability

Elimination of unknowns in a system of differential equations is often required when analysing (possibly nonlinear) dynamical systems models, where only a subset of variables are observable. One such analysis, identifiability, often relies on computing input-output relations via differential algebraic elimination. Determining identifiability, a natural prerequisite for meaningful parameter estimation, is often prohibitively expensive for medium to large systems due to the computationally expensive task of elimination. We propose an algorithm that computes a description of the set of differential-algebraic relations between the input and output variables of a dynamical system model. The resulting algorithm outperforms general-purpose software for differential elimination on a set of benchmark models from literature. We use the designed elimination algorithm to build a new randomized algorithm for assessing structural identifiability of a parameter in a parametric model. A parameter is said to be identifiable if its value can be uniquely determined from input-output data assuming the absence of noise and sufficiently exciting inputs. Our new algorithm allows the identification of models that could not be tackled before. Our implementation is publicly available as a Julia package at https://github.com/SciML/StructuralIdentifiability.jl

The charge ordered state in half-doped Bi-based manganites studied by 17^{17}O and 209^{209}Bi NMR

We present a $^{209}$Bi and $^{17}$O NMR study of the Mn electron spin correlations developed in the charge ordered state of Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ and Bi$_{0.5}$Ca$_{0.5}$MnO$_{3}$. The unusually large local magnetic field $^{209}H_{loc}$ indicates the dominant $6s^{2}$ character of the lone electron pair of Bi$^{3+}$-ions in both compounds. The mechanism connecting the $s$ character of the lone pairs to the high temperature of charge ordering $T_{CO}$ is still not clarified. The observed difference in $^{209}H_{loc}$ for Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ to Bi$_{0.5}$Ca$_{0.5}$MnO$_{3}$ is probably due to a decrease in the canting of the staggered magnetic moments of Mn$^{3+}$-ions from. The modification of the $^{17}$O spectra below $T_{CO}$ demonstrates that the line due to the apical oxygens is a unique local tool to study the development of the Mn spin correlations. In the AF state the analysis of the $^{17}$O spectrum of Pr$_{0.5}$Ca$_{0.5}$MnO$_{3}$ and Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ prompts us to try two different theoretical descriptions of the charge-ordered state, a site-centered model for the first manganite and a bond-centered model for the second one.Comment: 10 pages, 7 figure

Spin Susceptibility of Ga-Stabilized delta-Pu Probed by {69}^Ga NMR

Spin susceptibility of stabilized \delta phase in the Pu-Ga alloy is studied by measuring {69,71}^Ga NMR spectra and nuclear spin-lattice relaxation rate {69}T_{1}^{-1} in the temperature range 5 - 350 K. The shift ({69}^K) of the {69,71}^Ga NMR line and {69}^T_{1}^{-1} are controlled correspondingly by the static and the fluctuating in time parts of local magnetic field arisen at nonmagnetic gallium due to transferred hyperfine coupling with the nearest f electron environment of the more magnetic Pu. The nonmonotonic with a maximum around 150 K behavior of {69}^K(T) \chi_{s,5f}(T) is attributed to the peculiarities in temperature dependence of the f electron spin susceptibility \chi_{s,5f}(T) in \delta phase of plutonium. The temperature reversibility being observed in {69}^K(T) data provides strong evidence for an electronic instability developed with T in f electron bands near the Fermi energy and accompanied with a pseudogap-like decrease of \chi_{s,5f}(T) at T<150 K. The NMR data at high temperature are in favor of the mainly localized character of 5f electrons in \delta phase of the alloy with characteristic spin-fluctuation energy \Gamma(T) T^{0.35(5)}, which is close to $\Gamma(T) T^{0.5} predicted by Cox et al. [J. Appl. Phys. 57, 3166 (1985)] for 3D Kondo-system above T_Kondo}. The dynamic spin correlations of 5f electrons become essential to consider for {69}^T_{1}^{-1}(T) only at T<100 K. However, no NMR evidences favoring formation of the static magnetic order in \delta-Pu were revealed down to 5K .Comment: 6 pages, 4 figure

Applied science in the departmental universities: Inflated self-esteem and critical thinking (Оn an example of Federal Penitentiary Service’s universities of Russia)

Article addresses relevant as well as extremely broad topic for local universities related to the assessment of their scientific and practical efficiency. In the center of the author’s attention, there are reportable formal quantitative indicators in chase of which the educational institutions of the Federal Penitentiary Service’s (FPS ofRussia) distort the essence of applied scientific research, in fact, imitating it. Nevertheless, with their help these universities continue informing the public about their own scientific importance and high innovative potential, fully realized for the benefit of institutions which carry out penal sanctions. A critical analysis of such self-assessments obviously overstated and narrowly focused in terms of information reflects the content of this article. The indicator of social and / or economic effect obtained by the penal establishments from their actual implementation in practice could contribute to the objectivity of judgments about the results of the universities’ applied scientific research

On the social-labour relations in the Russian penitentiary system

Objective to state irrationality of the existing wagesforming system of the sentenced to imprisonment as the most important component of sociallabor relations in the penitentiary system and to justify the necessity of its reorganization including by restoring the functions of labour norms. Methods dialectical method of studying the phenomena and processes abstractlogical method method of analysis synthesis comparison of empirical and statistical data. Results the position is justified according to which the pay increase of convicts is based on the development and technological reequipment of industrial production of the criminalexecutive system and is intended to be linked with both positive dynamics of production and economic activity of the criminalexecutive system and effective the institution of their work rating. Scientific novelty the strategic relationship is identified between the wages of convicts and the state of industrial production in the penitentiary system. The futility is proved of solving social and labour problems in the penitentiary system on the quotinstitutional principlesquot that ignore the content of the objective law of value. Practical value is manifested in the ability to improve the management of social and labor processes for example to ensure the effective application of quotsocial liftsquot system to convicts in the penitentiary system including normsetting activities of its central authority

Прикладная наука в ведомственных вузах: проблемы объективной оценки эффективности

Article addresses relevant as well as extremely broad topic for local universities related to the assessment of their scientific and practical efficiency. In the center of the author’s attention, there are reportable formal quantitative indicators in chase of which the educational institutions of the Federal Penitentiary Service’s (FPS ofRussia) distort the essence of applied scientific research, in fact, imitating it. Nevertheless, with their help these universities continue informing the public about their own scientific importance and high innovative potential, fully realized for the benefit of institutions which carry out penal sanctions. A critical analysis of such self-assessments obviously overstated and narrowly focused in terms of information reflects the content of this article. The indicator of social and / or economic effect obtained by the penal establishments from their actual implementation in practice could contribute to the objectivity of judgments about the results of the universities’ applied scientific research.В статье затрагивается актуальная, равно как и весьма широкая, для отечественных вузов тема, связанная с оценкой их научно-практической результативности. В центре авторского внимания отчетные внутриведомственные показатели, в погоне за которыми образовательные заведения Федеральной службы исполнения наказаний искажают сущность прикладной научно-исследовательской деятельности, фактически занимаясь ее имитацией. Тем не менее, с их помощью данные вузы продолжают информировать общество o собственной научной значимости и высоком инновационном потенциале, полностью реализуемом в интересах органов и учреждений, исполняющих уголовные наказания. Критический анализ подобных самооценок, явно завышенных и в информативном отношении узконаправленных, отражает содержание данной работы. Объективности суждений по поводу итогов научно-исследовательской деятельности вузов мог бы способствовать показатель социального и/или экономического эффекта, получаемого пенитенциарными учреждениями от их реального воплощения на практике

Differential elimination for dynamical models via projections with applications to structural identifiability

Elimination of unknowns in a system of differential equations is often required when analysing (possibly nonlinear) dynamical systems models, where only a subset of variables are observable. One such analysis, identifiability, often relies on computing input-output relations via differential algebraic elimination. Determining identifiability, a natural prerequisite for meaningful parameter estimation, is often prohibitively expensive for medium to large systems due to the computationally expensive task of elimination. We propose an algorithm that computes a description of the set of differential-algebraic relations between the input and output variables of a dynamical system model. The resulting algorithm outperforms general-purpose software for differential elimination on a set of benchmark models from literature. We use the designed elimination algorithm to build a new randomized algorithm for assessing structural identifiability of a parameter in a parametric model. A parameter is said to be identifiable if its value can be uniquely determined from input-output data assuming the absence of noise and sufficiently exciting inputs. Our new algorithm allows the identification of models that could not be tackled before. Our implementation is publicly available as a Julia package at https://github.com/SciML/StructuralIdentifiability.jl