Blocking Wythoff Nim

The 2-player impartial game of Wythoff Nim is played on two piles of tokens. A move consists in removing any number of tokens from precisely one of the piles or the same number of tokens from both piles. The winner is the player who removes the last token. We study this game with a blocking maneuver, that is, for each move, before the next player moves the previous player may declare at most a predetermined number, $k - 1 \ge 0$, of the options as forbidden. When the next player has moved, any blocking maneuver is forgotten and does not have any further impact on the game. We resolve the winning strategy of this game for $k = 2$ and $k = 3$ and, supported by computer simulations, state conjectures of the asymptotic `behavior' of the $P$-positions for the respective games when $4 \le k \le 20$.Comment: 14 pages, 1 Figur

The Hut on the Garden Plot - Informal Architecture in Twentieth-Century Berlin

In Berlin, self-built huts and sheds were a part of the urban fabric for much of the twentieth century. They started to proliferate after the First World War and were particularly common after the Second World War, when many Berliners had lost their homes in the bombings. These unplanned buildings were, ironically, connected to one of the icons of German orderliness: the allotment. Often depicted as gnome-adorned strongholds of petty bourgeois virtues, garden plots were also the site of mostly unauthorized architecture and gave rise to debates about public health and civic order. This paper argues that the evolution and subsequent eradication of informal architecture was an inherent factor in the formation of the modern, functionally separated city. Modern Berlin evolved from a struggle between formal and informal, regulation and unruliness, modernization and pre-modern lifestyles. In this context, the ambivalent figure of the allotment dweller, who was simultaneously construed as a dutiful holder of rooted-to-the-soil values and as a potential threat to the well-ordered urban environment, evidences the ambiguity of many conceptual foundations on which the modern city was built

The Political Implications of Norway’s Sovereign Wealth Fund investments in Eastern and Central Europe

Although there has been vivid academic debate as to what extent Sovereign Wealth Funds (SWFs) are motivated by political reasons, it is rather clear that countries can use state-owned investment funds as a tool of their foreign policy. Even Barack Obama, during his initial presidential campaign in 2008 commented: “I am obviously concerned if these… sovereign wealth funds are motivated by more than just market consideration and that’s obviously a possibility”. This book looks at SWF activities in Central and Eastern Europe (CEE) to determine the main motives for SWF presence in CEE. Are the potential financial gains the only reason behind their investments? Are SWF activities in the region dangerous for the stability and security of the CEE countries? The book is pioneering analyses of SWFs behaviour in the region, based on empirical data collected from the Sovereign Wealth Fund Institute Transaction Database, arguably the most comprehensive and authoritative resource tracking SWF investment behaviour globally.Rozdział pochodzi z książki: Political Players? Sovereign Wealth Funds’ Investments in Central and Eastern Europe, T. Kamiński (ed.), Wydawnictwo Uniwersytetu Łódzkiego, Łódź 2017.The main goal of this chapter is to analyze investment policy of this state-controlled entity and provide the picture of its portfolio investment in Eastern and Central Europe Countries. For this purpose, the remainder of the chapter is organized in the following manner: in the next part facts and figures about the fund are presented, than the investment policy of the fund is described, after that the holdings of GPFG in Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia are analyzed, and finally the political implications of these investments are discussed with particular emphasis on the issue of risks. The chapter ends with conclusions.This book was published in frames of project “Political significance of the Sovereign Wealth Funds’ investments in the Central and Eastern Europe”. The project was financed by the Polish National Science Centre (Decision no. DEC-2012/07/B/HS5/03797)

Helium Cryostat for Experimental Study of Natural Turbulent Convection

V disertační práci je popsán heliový kryostat s experimentální válcovou konvekční celou pro studium proudění při přirozené konvekci za velmi vysokých Rayleigho čísel Ra (až do řádu 10^15) a Nusseltových čísel Nu (až do řádu 10^4). Pracovní látkou je studené 4He, které umožňuje díky výhodným fyzikálním vlastnostem dosažení velmi vysokých hodnot čísel Ra. Návrh kryostatu je založen na koncepci lázňových NMR kryostatů s nízkým odparem kryokapalin. Ve středu kryostatu je umístěna konvekční cela o průměru 300 mm a výšce 300 mm. Celu tvoří horní a spodní dno a výměnná střední část. Tyto díly jsou spojeny rozebíratelnými přírubami těsněnými indiovým drátem. Výměnná část umožňuje snadnou modifikaci geometrie cely. Hlavní přednost kryostatu spočívá v minimálním vlivu konstrukce cely a použitých materiálů na studovanou konvekci. Cela kryostatu je navržena pro pracovní tlaky do 250 kPa.The thesis focuses on the design of a helium cryostat with an experimental convection cell for the study of natural turbulent convection in the range of Rayleigh numbers Ra up to 1015 and Nusselt numbers Nu up to 104. Cryogenic 4He gas is used as a working fluid for experimental studies due to its advantageous properties that allow reaching very high Ra numbers. The cryostat design is based on the conception of low-loss NMR magnet cryostats. In the centre of the cryostat a cylindrical convection cell of 300 mm in diameter and 300 mm in height is placed. The cell is made of middle, top and bottom parts. These are jointed together by flanges sealed by indium wires. The middle part is exchangeable and allows the geometry of the cell to be modified. The cell is designed for measurements at pressures up to 250 kPa. The main advantage of this cryostat is the minimal influence of the cell design and materials on the studied convection.