Research reports

Latest additions:
2021-09-26
00:06
Assessment of Independent EEG Components Obtained by Different Methods for BCI Based on Motor Imagery
Húsek, Dušan ; Frolov, A. A. ; Kerechanin, J. V. ; Bobrov, P.D.
Eight methods of decomposition of a multichannel EEG signal are compared in terms of their ability to identify the most physiologically significant components. The criterion for the meaningfulness of a method is its ability to reduce mutual information between components; to create components that can be attributed to the activity of dipoles located in the cerebral cortex; find components that are provided by other methods and for this case; and at the same time, these components should most contribute to the accuracy of the BCI based on imaginary movement. Independent component analysis methods AMICA, RUNICA and FASTICA outperform others in the first three criteria and are second only to the Common Spatial Patterns method in the fourth criterion. The components created by all methods for 386 experimental sessions of 27 subjects were combined into more than 100 clusters containing more than 10 elements. Additionally, the components of the 12 largest clusters were analyzed. They have proven to be of great importance in controlling BCI, their origins can be modeled using dipoles in the brain, and they have been detected by several degradation methods. Five of the 12 selected components have been identified and described in our previous articles. Even if the physiological and functional origins of the rest of identified components’ are to be the subject of further research, we have shown that their physiological nature is at least highly probable.\n

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2021-09-26
00:06
SMV-2021-04: Pokročilá EDS analýza miniaturních maleb v EREM
Neděla, Vilém ; Tihlaříková, Eva
Vzorky byly analyzovány v experimentálně stanovených a optimalizovaných podmínkách environmentálního rastrovacího elektronového mikroskopu a pomocí EDS X-Ray mikro analyzátoru Bruker.

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2021-09-12
00:00
Shrinkage for Gaussian and t copulas in ultra-high dimensions
Anatolyev, Stanislav ; Pyrlik, Vladimir
Copulas are a convenient framework to synthesize joint distributions, particularly in higher dimensions. Currently, copula-based high dimensional settings are used for as many as a few hundred variables and require large data samples for estimation to be precise. In this paper, we employ shrinkage techniques for large covariance matrices in the problem of estimation of Gaussian and t copulas whose dimensionality goes well beyond that typical in the literature. Specifically, we use the covariance matrix shrinkage of Ledoit and Wolf to estimate large matrix parameters of Gaussian and t copulas for up to thousands of variables, using up to 20 times lower sample sizes. The simulation study shows that the shrinkage estimation significantly outperforms traditional estimators, both in low and especially high dimensions. We also apply this approach to the problem of allocation of large portfolios.

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2021-09-12
00:00
Make your own luck: the wage gains from starting college in a bad economy
Bičáková, Alena ; Cortes, G. M. ; Mazza, J.
Using data for nearly 40 cohorts of American college graduates and exploiting regional variation in economic conditions, we show robust evidence of a positive relationship between the unemployment rate at the time of college enrollment and subsequent annual earnings, particularly for women. This positive relationship cannot be explained by selection into employment or by economic conditions at the time of graduation. Changes in major field of study account for only about 10% of the observed earnings gains. The results are consistent with intensified effort exerted by students who experience bad economic times at the beginning of their studies.

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2021-09-12
00:00
Shifting punishment on minorities: experimental evidence of scapegoating
Bauer, Michal ; Cahlíková, J. ; Chytilová, Julie ; Roland, G. ; Želinský, T.
This paper provides experimental evidence showing that members of a majority group systematically shift punishment on innocent members of an ethnic minority. We develop a new incentivized task, the Punishing the Scapegoat Game, to measure how injustice affecting a member of one’s own group shapes punishment of an unrelated bystander (“a scapegoat”). We manipulate the ethnic identity of the scapegoats and study interactions between the majority group and the Roma minority in Slovakia. We find that when no harm is done, there is no evidence of discrimination against the ethnic minority. In contrast, when a member of one’s own group is harmed, the punishment ”passed” on innocent individuals more than doubles when they are from the minority, as compared to when they are from the dominant group. These results illuminate how individualized tensions can be transformed into a group conflict, dragging minorities into conflicts in a way that is completely unrelated to their behavior.

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2021-09-05
00:00
SMV-2021-03: Vývoj testovacích preparátů pro REM
Matějka, Milan ; Horáček, Miroslav ; Chlumská, Jana ; Kolařík, Vladimír ; Krátký, Stanislav
Výzkum, vývoj a realizace rozměrově přesných vzorků s reliéfními strukturami. Vzorky jsou určeny pro kalibraci parametrů rastrovacích elektronových mikroskopů (REM). Motivy struktur umožňují kontrolu a kalibraci zvětšení, pravoúhlosti a geometrického zkreslení. Byly vyvinuty přípravky pro technologické operace depozice a rezistu a pro operace leptání. Optimalizace bylo dosaženo i v oblasti transferu reliéfní struktury do křemíkové podložky při anizotropním leptání, díky modifikacím leptací aparatury. Pro kontrolu a vyhodnocení jakosti čipů mezi jednotlivými technologickými operacemi byly vyvinuty standardizované postupy.

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2021-09-05
00:00
SMV-2021-02: Vývoj a realizace amplitudové masky pro justáž optomechanických soustav
Meluzín, Petr ; Chlumská, Jana ; Kolařík, Vladimír ; Kopal, Jaroslav
Byla vyvinuta, realizována a charakterizována amplitudová maska dle podkladů zadavatele. K přípravě byl použit zápis motivu v zařízení s elektronovým svazkem a související technologické operace. Parametry byly ověřeny pomocí skenování povrchu sondou.

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2021-09-05
00:00
Zpráva o výsledcích mikroskopické analýzy vzorku umělého kamene z pískovcové arkády na zámku v Moravském Krumlově
Frankeová, Dita ; Koudelková, Veronika ; Bauerová, Pavla ; Slížková, Zuzana
V rámci stavebně-technického průzkumu byl proveden mikroskopický rozbor vzorku umělého kamene s využitím skenovacího elektronového mikroskopu a SEM‐EDS analýzy. Byla provedena charakterizace plniva a složek pojiva. Analýzy prokázaly, že pojivo umělého kamene je anorganické na bázi portlandského cementu

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2021-09-05
00:00
Zpráva o výsledcích mikroskopické analýzy vzorků malt z kleneb a opěr Vinohradských železničních tunelů
Bauerová, Pavla ; Frankeová, Dita ; Slížková, Zuzana
V rámci stavebně-technického průzkumu byl proveden mikroskopický rozbor vzorků historického betonu s využitím skenovacího elektronového mikroskopu a SEM‐EDS analýzy. Byla provedena charakterizace plniva a složek pojiva malt a identifikace produktů chemické koroze. Výsledky průzkumných prací byly použity jako podklad pro návrh rekonstrukce objektu.\n

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2021-08-22
00:07
Paternal circular migration and development of socio-emotional skills of children left behind
Adunts, Davit
This study investigates the short-run effect of paternal absence due to circular migration on the socio-emotional skills of their children left behind. To address the endogeneity of the migration decision, and building on previous studies, this study focuses on children whose fathers have all engaged in circular migration. Furthermore, using quasi-exogenous variation in the timing of return migration induced by bilateral migration laws between Ukraine and Poland, I circumvent the bias related to the return migration decision. The findings of this study suggest that current paternal absence due to circular migration negatively affects the socioemotional skills of children left behind. Overall, this result suggests that circular migration is not necessarily a „triple-win“ solution that benefits all involved parties.

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