Magnetism without magnetic impurities in oxides ZrO2 and TiO2

We perform a theoretical study of the magnetism induced in transition metal dioxides ZrO2 and TiO2 by substitution of the cation by a vacancy or an impurity from the groups 1A or 2A of the periodic table, where the impurity is either K or Ca. In the present study both supercell and embedded cluster methods are used. It is demonstrated that the vacancy and the K-impurity leads to a robust induced magnetic moment on the surrounding O-atoms for both the cubic ZrO2 and rutile TiO2 host crystals. On the other hand it is shown that Ca-impurity leads to a non magnetic state. The native O-vacancy does not induce a magnetic moment in the host dioxide crystal.Comment: 7 pages, 5 figures, submitte

Electronic structure and non-magnetic character of δ\delta-Pu-Am alloys

The {\em around-mean-field} LSDA+U correlated band theory is applied to investigate the electronic and magnetic structure of $fcc$-Pu-Am alloys. Despite a lattice expansion caused by the Am atoms, neither tendency to 5$f$ localization nor formation of local magnetic moments on Pu atoms in Pu-Am alloys are found. The $5f$-manifolds in the alloys are calculated being very similar to a simple weighted superposition of elemental Pu and Am $5f$-states

The background of the Russo-Chechen conflict

V prosinci 1994 ruská vojska zaútočila na Čečensko. První pokus o pokoření odbojné země ještě úspěšný nebyl a vyčerpanému Rusku nezbylo než v srpnu 1996 podepsat potupné příměří v Chasavjurtu. Nová válka se rozhořela na podzim 1999 a Rusko v ní po úporné snaze triumfovalo, i když partyzánské boje probíhají vlastně dosud. Celkově během obou válek zemřelo více než 100 tisíc Čečenců, většinou civilistů, a velká část infrastruktury země lehla popelem. Z lidského hlediska to je nepochybně strašná tragédie. Z toho historického jde jen o poslední pokračování více než dvousetletého krvavého zápasu Čečenců s moskevským impériem. Úkolem předkládané práce je najít odpověd' na otázku, proč se Čečensko jako jediné ze všech bývalých autonomních republik RSFSR dostalo do přímého válečného střetu s Moskvou. Už z podstaty historické práce plyne, že taková odpověď může být subjektivní a nejednoznačná. Autor práce chce proto zvážit a zevrubně popsat všec1my důležité faktory, které mohly tento vývoj způsobit a nechat na případném čtenáři, aby si ze shromážděných faktů vyvodil vlastní závěr

Spin polarization of Bloch states and Hall currents in GaAs quantum wells

Real-space distribution of the Hall current densities and their spin polarization in non-magnetic zinc-blende semiconductors is analysed. It is shown that the applied current gives rise to a local spin polarization accompanied by spin-polarized Hall-current densities. Especially for hole carriers they are responsible for transferring spins of different orientation in opposite directions, spin Hall current, while the total Hall current vanishes

CsFEVER and CTKFacts: Acquiring Czech data for fact verification

In this paper, we examine several methods of acquiring Czech data for automated fact-checking, which is a task commonly modeled as a classification of textual claim veracity w.r.t. a corpus of trusted ground truths. We attempt to collect sets of data in form of a factual claim, evidence within the ground truth corpus, and its veracity label (supported, refuted or not enough info). As a first attempt, we generate a Czech version of the large-scale FEVER dataset built on top of Wikipedia corpus. We take a hybrid approach of machine translation and document alignment; the approach and the tools we provide can be easily applied to other languages. We discuss its weaknesses and inaccuracies, propose a future approach for their cleaning and publish the 127k resulting translations, as well as a version of such dataset reliably applicable for the Natural Language Inference task - the CsFEVER-NLI. Furthermore, we collect a novel dataset of 3,097 claims, which is annotated using the corpus of 2.2M articles of Czech News Agency. We present its extended annotation methodology based on the FEVER approach, and, as the underlying corpus is kept a trade secret, we also publish a standalone version of the dataset for the task of Natural Language Inference we call CTKFactsNLI. We analyze both acquired datasets for spurious cues - annotation patterns leading to model overfitting. CTKFacts is further examined for inter-annotator agreement, thoroughly cleaned, and a typology of common annotator errors is extracted. Finally, we provide baseline models for all stages of the fact-checking pipeline and publish the NLI datasets, as well as our annotation platform and other experimental data.Comment: submitted to LREV journal for review, resubmission, changed title according to reviewer suggestio