A sign pattern matrix (or nonnegative sign pattern matrix) is a matrix whose entries are from the set {+,−, 0} ({+, 0}, respectively). The minimum rank (or rational minimum rank) of a sign pattern matrix A is the minimum of the ranks of the matrices (rational matrices, respectively) whose entries have signs equal to the corresponding entries of A. Using a correspondence between sign patterns with minimum rank r ≥ 2 and point-hyperplane configurations in Rr−1 and Steinitz’s theorem on the rational realizability of 3-polytopes, it is shown that for every nonnegative sign pattern of minimum rank at most 4, the minimum rank and the rational minimum rank are equal. But there are nonnegative sign patterns with minimum rank 5 whose rational minimum rank is greater than 5. It is established that every d-polytope determines a nonnegative sign pattern with minimum rank d + 1 that has a (d + 1) × (d + 1) triangular submatrix with all diagonal entries positive. It is also shown that there are at most min{3m, 3n} zero entries in any condensed nonnegative m × n sign pattern of minimum rank 3. Some bounds on the entries of some integer matrices achieving the minimum ranks of nonnegative sign patterns with minimum rank 3 or 4 are established., Wei Fang, Wei Gao, Yubin Gao, Fei Gong, Guangming Jing, Zhongshan Li, Yanling Shao, Lihua Zhang., and Obsahuje seznam literatury
Príspevok pojednáva o realizácii dynamických vysokotlakovžch experimentov s využitím generátorov rázových vĺn s dôrazom na využitie vysoko intenzívnych laserových impulzov. Keďže materiál vystavený extrémnym podmienkam prechádza rôznými štruktúrnými zmenami, v práci je predstavený základný koncept realizácie časovo rozlíšiteĺnej röntgenovoj difrakcie v časových škálach kratších ako nanosekundy za pomoci impulzných laserom indukovaných röntgenových plazmových zdrojov., This article discusses the implementation of high-pressure dynamic experiments using shock-wave generators with emphasis on the use of ultra-intense laser pulses. At extreme conditions materials undergo various fast structural changes, this article presents the basic concept of the realization of time-resolved X-ray diffraction in time scales shorter than nanoseconds using laser driven X-ray plasma sources., Štefan Michalik., and Obsahuje seznam literatury
This article studies public processions in Bohemia between the fourteenth and early seventeenth centuries. It analyzes processional functions in the context of the kingdom’s tumultuous religious development, including the Hussite revolution and subsequent co-existence of Catholic and utraquist churches. Three case studies of processions in Prague (imperial relics for ostensio reliquiarum, post-Hussite processions of Corpus Christi), Tabor (which rejects traditional forms of devotion yet employs processions in its religious and social life) and the mining town of Kutná Hora (Corpus Christi processions) illustrate the great variability of processional function: religious (indoctrination, mobilization, subversion via parody), social (cohesion), political (representation, competition) and military. and Jan Hrdina, Aleš Mudra, Marcela K. Perett.
We give a classification of Hopf real hypersurfaces in complex hyperbolic two-plane Grassmannians
${\rm SU}_{2,m}/S(U_2{\cdot}U_m)$ with commuting conditions between the restricted normal Jacobi operator $\overline{R}_N\phi$ and the shape operator $A$ (or the Ricci tensor $S$)., Doo Hyun Hwang, Eunmi Pak, Changhwa Woo., and Obsahuje bibliografii
In order to re-evaluate the presence and relative quantity of 2b and 2x/d myosin heavy chain (MyHC) transcripts in rat slow soleus muscle by using real time RT-PCR we have compared the available relevant cDNA sequences and designed a new set of primers having similar melting temperatures, matching separate MyHC exons in the regions of maximal differences in MyHC coding sequences, and containing G or C at the 3́-end. These also yielded PCR products of corresponding length, which is an important requirement for real time RT-PCR quantification. The experiments were performed on 8- month-old inbred female Lewis strain rats used in our current study of regenerating transplanted muscles. The real time RT-PCR measurement confirmed the expression of all four MyHC mRNAs (type 1, 2a, 2x/d and 2b) in both fast extensor digitorum longus and slow soleus muscles, although in the soleus muscle of adult rats, only type 1 and 2a protein isoforms can be usually detected, J. Žurmanová, F. Půta, R. Stopková, T. Soukup., and Obsahuje bibliografii a bibliografické odkazy