In October 2005 local seismic monitoring started in the area of the Hronov-Poříčí Fault Zone. In the present paper we summarize seismic measurements using a small-aperture seismic array Ostaš. Parameters of the array and methodology of the data registration and processing are described. The list of local microearthquakes during two years of registration is presented., Jiří Málek, Milan Brož, Vladimír Stejskal and Jaroslav Štrunc., and Obsahuje bibliografické odkazy
We propose a new localization result for the leading eigenvalue and eigenvector of a symmetric matrix A. The result exploits the Frobenius inner product between A and a given rank-one landmark matrix X. Different choices for X may be used, depending on the problem under investigation. In particular, we show that the choice where X is the all-ones matrix allows to estimate the signature of the leading eigenvector of A, generalizing previous results on Perron-Frobenius properties of matrices with some negative entries. As another application we consider the problem of community detection in graphs and networks. The problem is solved by means of modularity-based spectral techniques, following the ideas pioneered by Miroslav Fiedler in mid-’70s. We show that a suitable choice of X can be used to provide new quality guarantees of those techniques, when the network follows a stochastic block model., Dario Fasino, Francesco Tudisco., and Obsahuje seznam literatury
This paper discusses a simple logical approach to solving Sudoku puzzles, which may be interpreted as a mental model of the puzzle. The model employs an auxiliary matrix 9x9, which is formed from the matrix specifying initial given values of the puzzle in such a way that its empty squares are filled by lists of candidate values. These lists are determined by initial values together with the puzzle constraints: each column/row/subarea 3x3 is occupied by integers 1, 2, ..., 9 appearing only once. Applying the simple logical rules such as if..., then..., this auxiliary matrix is subsequently simplified in such a way that we reduce the set of alternative possibilities, where in a final stage each position of auxiliary matrix is occupied just by one integer from {1,2,...,9} and the resulting matrix satisfies the above mentioned constraints. The logical rules used may be hierarchically arranged in a sequence of increasing complexity of their preceding parts. Therefore, Sudoku puzzles may be classified according to the complexity of their solution; from the simplest puzzles to the most complex by using the rules and a back-track search., V práci je diskutovaný jednoduchý logický prístup k riešeniu hry Sudoku, ktorý môže byť taktiež interpretovaný ako mentálny model tejto hry. Použitý model využíva pracovnú maticu 9x9, ktorá je vytvorená z matice špecifikujúcej počiatočnú pozíciu hry tak, že prázdne pozície sú zaplnené alternatívnymi možnosťami určenými z počiatočnej pozície pomocou podmienok tak, aby každý riadok/stĺpec/oblasť 3x3 obsahoval čísla 1, 2, ..., 9 prave raz. Použitím jednoduchých logických pravidiel typu if..., then... túto pracovnú maticu postupne zjednodušíme tak, že redukujeme výskyt alternatívnych možností, až v konečnej fáze úpravy matice v každej pozícii máme práve jedno číslo, pričom táto výsledná matica vyhovuje vyššie uvedeným podmienkam. Použité logické pravidlá pre zjednodušenie Sudoku môžu byť hierarchicky usporiadané podl'a rastúcej zložitosti ich podmienky (antecedentu). Potom hry Sudoku môžu byť klasifikované podl'a zložitosti ich riešenia; od jednoduchých hier až po vel'mi zložité (diabolské), kde je potrebné použiť pravidlá, ktoré vo svojich podmienkach obsahujú spätné prehl'adávanie pracovnej matice., Vladimír Kvasnička, Michal Cádrik., and Obsahuje bibliografii
The aim of this study was a comparison of risk stratification for death in patients after myocardial infarction (MI) and of risk stratification for malignant arrhythmias in patients with implantable cardioverter-defibrillator (ICD). The individual risk factors and more complex approaches were used, which take into account that a borderline between a risky and non-risky value of each predictor is not clear-cut (fuzzification of a critical value) and that individual risk factors have different weight (area under receiver operating curve - AUC or Sommers´ D - Dxy). The risk factors were baroreflex sensitivity, ejection fraction and the number of ventricular premature complexes/hour on Holter monitoring. Those factors were evaluated separately and they were involved into logit model and fuzzy models (Fuzzy, Fuzzy-AUC, and Fuzzy-Dxy). Two groups of patients were examined: a) 308 patients 7-21 days after MI (23 patients died within period of 24 month); b) 53 patients with left ventricular dysfunction examined before implantation of ICD (7 patients with malignant arrhythmia and electric discharge within 11 month after implantation). Our results obtained in MI patients demonstrated that the application of logit and fuzzy models was superior over the risk stratification based on algorithm where the decision making is dependent on one parameter. In patients with implanted defibrillator only logit method yielded statistically significant result, but its reliability was doubtful because all other tests were statistically insignificant. We recommend evaluating the data not only by tests based on logit model but also by tests based on fuzzy models., P. Honzík ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Článek se zabývá dosažením prostorového superrozlišení pomocí lokální fotoluminiscence (PL) na vnořených samoorganizovaných kvantových tečkách. Pro rozlišení jednotlivých teček je použit rastrovací odrazný mikroskop v optickém blízkém poli (SNOM). PL intenzita je hlavní složkou pro spojení nepokoveného vláknového hrotu s luminiscenční kvantovou tečkou a vykazuje exponenciální pokles s rostoucí vzdáleností vzorku od hrotu sondy. Výsledky jsou nezávislé na použité vlnové délce světelníého zdroje. Při vyhodnocování obrazu jsou oddělovány příspěvky PL intentzity od blízkého a vzdáleného pole. Takto můžeme získat fotoluminiscenční obrazy vnořených kvantových teček s prostorovým rozlišením lepším než 300 nm., Dana Košťálová., and Obsahuje seznam literatury