Speleothems in 6 sandstone caves in the Bohemian Paradise (Český ráj) were dated by means of 14C and U-series methods. Stable isotopes of C and O, FAAS, IR, XRD, XRF and SEM were used to characterize the carbonate material and its source. Stable isotopes (C and O) composition of speleothems in two caves corresponds to values characteristic for cave speleothems in Central Europe. In other caves they indicate evaporation and fast carbon dioxide escape during carbonate precipitation. The speleothems from the Krtola Cave were deposited between 8 and 13 kyr BP. Speleothems were deposited 5-8 kyr BP in the Sintrová, Mrtvé Údolí and U Studánky caves. Calcite coatings on smooth sandstone surfaces in studied caves demonstrate that cave walls did not retreat even a few mm in the last 5-8 kyr since speleothem deposition and are thus not evolving under recent climatic conditions. Most of the cave ceilings and walls are at present time indurated by hardened surfaces, which protect the sandstone from erosion. Sandstone caves probably intensively evolved either during or at the end of the Last Glacial period. There are two different erosion mechanisms which might have formed/reshaped the caves at that time: A) In the case of permafrost conditions: Repeated freeze/melt cycles affecting sandstone pore space followed by the transport of fallen sand grains by minor temporary trickles. We expect that heat was transmitted by air circulating between the cave and the surface; B) Seepage erosion of sandstone during the melting of permafrost, prior forming of case hardening., Jiří Bruthans, Jana Schweigstillová, Petr Jenč, Zdeňka Churáčková and Petr Bezdička., and Obsahuje bibliografii
Our own study as well as others have previously reported that hypoxia activates 15-lipoxygenase (15-LO) in the brain, causing a series of chain reactions, which exacerbates ischemic stroke. 15-hydroxyeicosatetraenoic acid (15-HETE) and 15-oxoeicosatetraenoic acid (15-oxo-ETE/15-KETE) are 15-LO-specific metabolites of arachidonic acid (AA). 15-HETE was found to be rapidly converted into 15-oxo-ETE by 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in some circumstances. We have demonstrated that 15-HETE promotes cerebral vasoconstriction during hypoxia. However, the effect of 15-oxo-ETE upon the contraction of cerebral vasculature remains unclear. To investigate this effect and to clarify the underlying mechanism, we performed immunohistochemistry and Western blot to test the expression of 15-PGDH in rat cerebral tissue, examined internal carotid artery (ICA) tension in isolated rat ICA rings. Western blot and reverse transcription polymerase chain reaction (RT-PCR) were used to analyze the expression of voltage-gated potassium (Kv) channels (Kv2.1, Kv1.5, and Kv1.1) in cultured cerebral arterial smooth muscle cells (CASMCs). The results showed that the levels of 15-PGDH expression were drastically elevated in the cerebral of rats with hypoxia, and 15-oxo-ETE enhanced ICA contraction in a dose-dependent manner. This effect was more significant in the hypoxic rats than in the normoxic rats. We also found that 15-oxo-ETE significantly attenuated the expression of Kv2.1 and Kv1.5, but not Kv1.1. In conclusion, these results suggest that 15-oxo-ETE leads to the contraction of the ICA, especially under hypoxic conditions and that specific Kv channels may play an important role in 15-oxo- ETE-induced ICA constriction., Di Wang, Yu Liu, Ping Lu, Daling Zhu, Yulan Zhu., and Obsahuje bibliografii
The Union of Czech Mathematicians and Physicists celebrated the 150th anniversary of its foundation. On the occasion of this anniversary on March 28, 2012, the Union at Karolinum, the seat of the Charles University, a festive ceremony, attended by outstanding personalities headed by the President of the Czech Republic Vaclav Klaus. The Union was founded in 1862 as the Association for Free Lectures in Mathematics and Physics. From the beginning, its goal was the improvement of the teaching physics and mathematics at schools on all levels and of all types and further, to support and promote the development of those sciences. As a consequence of patriotic efforts, the Association was enlarged in 1869 into the Union of Czech Mathematicians and Physicists. In the early 1950s, the Union had to transfer its property to the newly established Czechoslovak Academy of Sciences (CSAV) and it became a learned society affiliated with CSAV. The mathematical part of its library became the basis of the library of the Mathematical Institute of CSAV, and is located there at present. Today, the Union has about 2,800 members. The Union itself, or in collaboration with universities and research institutes, organizes national as well as international conferences, symposia, seminars, and Summer or Winter schools. The Union follows the teaching of mathematics and physics in schools and proposes improvements. It encourages talented students and participates in the organization of the Mathematical and Physical Olympiad and other student competitions. Czech Post has issued a stamp commemorating the 150"i Anniversary of the Foundation of the Union of Czech Mathematicians and Physicists. and Martina Bečvárová.
The Velvet Revolution was a non-violent uprising in Czechoslovakia that saw the overthrow of the Communist government. On November 17, 1989, police suppressed a peaceful student demonstration in Prague. Among the protesters were many young employees of Czechoslovak Academy of Sciences. Based on the November events, civil forums were created at worksplaces. In consequences of the political evolvement, some of the compromised directors from institutes left their positions and during the following six months all directors had to be evaluated. Scientific committies began to form. On November 6, 1989, the entire presidium of ČSAV resigned and December 12, the Chamber of elected representatives of ČSAV was established. This organ became a carrier of fundamental changes, for example the first Czech science foundation was set up and proposals for evaluation of the institutes formed. The new organization structures of Academy were created. and Antonín Kostlán.