2,150 research outputs found

    Healthiness from Duality

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    Healthiness is a good old question in program logics that dates back to Dijkstra. It asks for an intrinsic characterization of those predicate transformers which arise as the (backward) interpretation of a certain class of programs. There are several results known for healthiness conditions: for deterministic programs, nondeterministic ones, probabilistic ones, etc. Building upon our previous works on so-called state-and-effect triangles, we contribute a unified categorical framework for investigating healthiness conditions. We find the framework to be centered around a dual adjunction induced by a dualizing object, together with our notion of relative Eilenberg-Moore algebra playing fundamental roles too. The latter notion seems interesting in its own right in the context of monads, Lawvere theories and enriched categories.Comment: 13 pages, Extended version with appendices of a paper accepted to LICS 201

    ANALYSIS OF THE CHEMICAL COMPOSITION OF CHAROITE ROCKS

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    The unique charoite mineralization, established on the Murun alkaline massif in the northwestern part of the Aldan shield on the border of the Irkutsk region and Yakutia, is still of great interest to some of researchers (geologists, crystallographers, geochemists, etc.). The outcrops of charoite-bearing rocks at the “Sirenevyi Kamen” deposit are noted both in the indigenous outcrops and in eluvial clatters [Bondarenko, 2009].The unique charoite mineralization, established on the Murun alkaline massif in the northwestern part of the Aldan shield on the border of the Irkutsk region and Yakutia, is still of great interest to some of researchers (geologists, crystallographers, geochemists, etc.). The outcrops of charoite-bearing rocks at the “Sirenevyi Kamen” deposit are noted both in the indigenous outcrops and in eluvial clatters [Bondarenko, 2009]

    Coherent spin dynamics of electrons and holes in semiconductor quantum wells and quantum dots under periodical optical excitation: resonant spin amplification versus spin mode-locking

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    The coherent spin dynamics of resident carriers, electrons and holes, in semiconductor quantum structures is studied by periodical optical excitation using short laser pulses and in an external magnetic field. The generation and dephasing of spin polarization in an ensemble of carrier spins, for which the relaxation time of individual spins exceeds the repetition period of the laser pulses, are analyzed theoretically. Spin polarization accumulation is manifested either as resonant spin amplification or as mode-locking of carrier spin coherences. It is shown that both regimes have the same origin, while their appearance is determined by the optical pump power and the spread of spin precession frequencies in the ensemble

    Topological energy barrier for skyrmion lattice formation in MnSi

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    We report the direct measurement of the topological skyrmion energy barrier through a hysteresis of the skyrmion lattice in the chiral magnet MnSi. Measurements were made using small-angle neutron scattering with a custom-built resistive coil to allow for high-precision minor hysteresis loops. The experimental data was analyzed using an adapted Preisach model to quantify the energy barrier for skyrmion formation and corroborated by the minimum-energy path analysis based on atomistic spin simulations. We reveal that the skyrmion lattice in MnSi forms from the conical phase progressively in small domains, each of which consisting of hundreds of skyrmions, and with an activation barrier of several eV.Comment: Final accepted versio

    The simulation model of the computer cluster

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    Simulation is often used in cases when it is impossible to carry out experiments with real complex objects. The article represents the description of the computer cluster simulation model. Parameters, which affect the cluster performance, were selected, a simulation model was designed, and experiments were conducted. The obtained model allowed finding the optimal variant of the cluster performance, which consists of five computers

    Optimization of the subject matter of profile training disciplines for bachelors' vocational education on the basis of occupational standards

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    Applicability of the issue under study is conditioned by the need in development of principal educational programs by higher education institutions with accounting for requirements of appropriate occupational standards and necessity in reviewing of the requirements of occupational standards and reflecting them within the scope of competences formed. The paper is aimed at substantiation of the subject matter of profile training disciplines for vocational education of bachelors within the context of competence and process approaches and with accounting for occupational standards. The leading method of study of this issue is modeling which allows considering the issue under study as a process of recognized accounting of requirements of appropriate occupational standards wherein employers' opinions are fixed in the regulatory mode. The structural-functional model of selection of the subject matter of profile disciplines for the training program is developed; the following algorithms are developed: 1) of analysis of occupational standards; 2) of comparing of occupational standards with curriculum disciplines; 3) of analysis of the subject matter of labour functions, labour actions, knowledge and skills when developing working programs and assessment resources funds; the model has been successfully tested on the example of profile training of vocational education bachelors. The paper presents the structure-functional model of selection of the subject matter of profile disciplines of the educational program with taking into account of occupational standards requirements which define competences acquired by a graduate, i.e. his/her ability to use knowledge, skills and personal qualities in accordance with the occupational activity; the process approach to implementation of this model is applied. © Authors
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