Russell’s ramified type theory did not allow generalising in mathematical practice, which is why Russell introduced the axiom of reducibility that postulated the existence of a predicative function of the lowest order
formally equivalent to any propositional function of a higher order. This historiographical paper deals with the nature of the axiom of reducibility – that Russell expected to eliminate the paradoxes undermining the project of logicism – in the context of theory of types. The axiom has been intensively criticized as an illogical principle that actually had a destructive effect on the ramified hierarchy of types. Instead of the well-known criticisms by famous thinkers (Ramsey, Chwistek, Wittgenstein, Quine), this paper focuses on Waismann’s analysis of the axiom that originated in the period of his collaboration with Wittgenstein and showed that the axiom is not a logical principle because it does not correspond with the concept of tautology as proposed in the Tractatus. Although Waismann’s contribution went almost unnoticed, overshadowed by Wittgenstein’s own work, it is an illustrative example of the reception of Russell’s thinking within the Vienna Circle.
Ve dnech 9. až 12. prosince 2013 rokovali v Praze odborníci o dalším vývoji v oblasti kosmického výzkumu v rentgenové části spektra. V novorenesanční vile Lanna v pražské Bubenči, tradičním dějišti workshopů AXRO, se setkali nejen vědci a technologové, ale především zástupci světových kosmických agentur, kteří společně koordinovali postup při plánování a budování nových rentgenových satelitů. Ty by měly do 15 let nahradit a překonat stávající, jako jsou SWIFT, INTEGRAL, XMM-Newton nebo Chandra. Své referáty předneslo 40 účastníků z Evropy, USA, Japonska nebo Číny. and Martin Blažek.
International Workshop on Astronomical X-Ray-Optics (AXRO) organized by the Institute of Astronomy of the CAS was focused on presentation and discussion of recent and future technologies for future X-ray astronomy missions. One session was aimed on astrophysical aspects of X-ray telescopes/satellites, in which some review talks were given from leading scientists in this field plus some presentations of relevant Czech scientists. The goal of the workshop was to present and to discuss recent and future technologies for X-ray astronomy missions. These missions require development of mostly inovative technologies, and discussed the possibilities, the results obtained so farm and new ideas in detail. It is obvious that the requirements of future large space X-ray optics based on Si wafers, advanced glass forming for precise X-ray optics, but also other possible technologies and alternatives, as well as related advanced metrology, measurements and tests. and Martin Blažek.
Monstrozní, obří, tajemné, vražedné, vymykající se známým fyzikálním zákonům, přímo nepozorovatelné brány do jiných vesmírů... Jen málokteré objekty v kosmu se honosí tak barvitými a rozpruplnými označeními jako černé díry. A současně málokteré tolik dráždí zvědavost nejen veřejnosti, ale také astronomů, kosmologů a (astro)fyziků, kteří se snaží kousek po kousku odrhrnout roušku jejich tajemství. Černé díry se však nehodlají vzdát a vzdorovitě připravují jedno překvapení za druhým. and Jana Olivová, Michal Švanda.
In July 2012, new archaelogical campaign in Western Shephelah in Israel at the ancient site of Tel Azekah has been opened. The excavations are conducted by prestigious international consortium of universities among which also Charles University of Prague and there specifically The Centre for Biblical Studies of the Czech Academy of Sciences are involved. The site under scrutiny was populated throughout many period including Late Bronze, Iron Age and presumably also the Persian or the Hasmonaean time. Though already excavated at the end of 19th century, present campaign aims to raise new data from the site with support of latter-day technologies so that the complex picture of its abudant history can be elaborated., Filip Čapek., and Obsahuje seznam literatury
The behaviour of B-chromosomes in meiosis was studied in 44 males of yellow- necked mouse, Apodemus flavicollis. The Bs behave in a non-Mendelian fashion during meiosis I i.e., appear as univalents, regardless of the number of Bs, and segregate in a random fashion. The meiotic drag of Bs, resulting from Bs lagging and premature division of Bs into chromatids, was found in 1B animals. The Bs drag amounts to about 6% of cells and is not substantial; however due to dispensable nature of Bs, it has to be compensated through drive in females or heterotic effects of Bs. This result gives support for the heterotic model of Bs evolution in A. flavicollis. On the other hand, the number of chiasmata on A-chromosomes showed increasing tendency with the number of Bs in the karyotype. As the chiasma effect is characteristic for parasitic Bs, it gives support for the parasitic model of Bs evolution. With contrasting results, the hypothesis of a combined model of Bs evolution, in which the fitness of B-bearers changes around the year or in different environmental conditions is discussed.