### Browsing by Department "Charles University"

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Item Cation-sensitive compartmentalization in metallacarborane containing polymer nanoparticles(ROYAL SOC CHEMISTRY, 2016) Dordovic, Vladimir; Uchman, Mariusz; Reza, Mehedi; Ruokolainen, Janne; Zhigunov, Alexander; Ivankov, Olexandr I.; Matějíček, Pavel; Charles University; Department of Applied Physics; Czech Academy of Sciences; Taras Shevchenko National University of KyivAlkaline cations (Li+, Na+ and K+) are introduced as agents suitable to control compartmentalization in metallacarborane-rich nanoparticles of double-hydrophilic block copolymer poly(ethylene oxide)-block-poly(2-alkyloxazoline), PEO-POX. Interaction of the metallacarborane (cobalt bis(dicarbollide) anion) with PEO-POX is based mainly on dihydrogen bonding between metallacarborane boron clusters and the polymer backbone resulting in compact nanoparticles. However, the cations are a crucial factor as to whether interaction with PEO or POX segments is preferred. Changes in the bulk concentration of alkaline cations can thus provoke changes in the inner structure of polymeric nanoparticles, which is accompanied by exchange of boron clusters and alkaline cations like Li+. Because of the biomedical importance of metallacarboranes, their conjugates and also lithium salts, the hybrid nanoparticles can act as stimuli-responsive systems for drug delivery.Item Flexible integrated functional depths(INT STATISTICAL INST, 2021-02) Nagy, Stanislav; Helander, Sami; van Bever, Germain; Viitasaari, Lauri; Ilmonen, Pauliina; Charles University; Department of Mathematics and Systems Analysis; Universite de Namur; Department of Information and Service Management; Statistics and Mathematical Data ScienceThis paper develops a new class of functional depths. A generic member of this class is coined Jth order kth moment integrated depth. It is based on the distribution of the cross-sectional halfspace depth of a function in the marginal evaluations (in time) of the random process. Asymptotic properties of the proposed depths are provided: we show that they are uniformly consistent and satisfy an inequality related to the law of the iterated logarithm. Moreover, limiting distributions are derived under mild regularity assumptions. The versatility displayed by the new class of depths makes them particularly amenable for capturing important features of functional distributions. This is illustrated in supervised learning, where we show that the corresponding maximum depth classifiers outperform classical competitors.Item On quadratic Waring’s problem in totally real number fields(American Mathematical Society, 2023-04-01) Krásenský, Jakub; Yatsyna, Pavlo; Charles University; Algebra and Discrete Mathematics; Department of Mathematics and Systems AnalysisWe improve the bound of the g-invariant of the ring of integers of a totally real number field, where the g-invariant g(r) is the smallest number of squares of linear forms in r variables that is required to represent all the quadratic forms of rank r that are representable by the sum of squares. Specifically, we prove that the gOK(r) of the ring of integers OK of a totally real number field K is at most gZ([K : Q]r). Moreover, it can also be bounded by gOF ([K : F]r + 1) for any subfield F of K. This yields a subexponential upper bound for g(r) of each ring of integers (even if the class number is not 1). Further, we obtain a more general inequality for the lattice version G(r) of the invariant and apply it to determine the value of G(2) for all but one real quadratic field.Item Static properties and current-induced dynamics of pinned 90 magnetic domain walls under applied fields(2018-08-21) BaláŽ, Pavel; Hämäläinen, Sampo J.; Van Dijken, Sebastiaan; Charles University; Nanomagnetism and Spintronics; Department of Applied PhysicsMagnetic domain walls are pinned strongly by abrupt changes in magnetic anisotropy. When driven into oscillation by a spin-polarized current, locally pinned domain walls can be exploited as tunable sources of short-wavelength spin waves. Here, we develop an analytical framework and discrete Heisenberg model to describe the static and dynamic properties of pinned domain walls with a head-to-tail magnetic structure. We focus on magnetic domain walls that are pinned by 90 rotations of uniaxial magnetic anisotropy. Our model captures the domain wall response to a spin-transfer torque that is exerted by an electric current. Model predictions of the domain wall resonance frequency and its evolution with magnetic anisotropy strength and external magnetic field are compared to micromagnetic simulations.Item The WMT'18 Morpheval test suites for English-Czech, English-German, English-Finnish and Turkish-English(2018-10-31) Burlot, Franck; Scherrer, Yves; Ravishankar, Vinit; Bojar, Ondřej; Grönroos, Stig-Arne; Koponen, Maarit; Nieminen, Tommi; Yvon, François; Lingua Custodia; University of Helsinki; Charles University; Centre of Excellence in Computational Inference, COIN; University of Turku; Université Paris-SaclayProgress in the quality of machine translation output calls for new automatic evaluation procedures and metrics. In this paper, we extend the Morpheval protocol introduced by Burlot and Yvon (2017) for the English-toCzech and English-to-Latvian translation directions to three additional language pairs, and report its use to analyze the results of WMT 2018’s participants for these language pairs. Considering additional, typologically varied source and target languages also enables us to draw some generalizations regarding this morphology-oriented evaluation procedure