Fifty years of Hubbard and Anderson lattice models: from magnetism to unconventional superconductivity - A brief overview

We briefly overview the importance of Hubbard and Anderson-lattice models as applied to explanation of high-temperature and heavy-fermion superconductivity. Application of the models during the last two decades provided an explanation of the paired states in correlated fermion systems and thus extended essentially their earlier usage to the description of itinerant magnetism, fluctuating valence, and the metal-insulator transition. In second part, we also present some of the new results concerning the unconventional superconductivity and obtained very recently in our group. A comparison with experiment is also discussed, but the main emphasis is put on rationalization of the superconducting properties of those materials within the real-space pairing mechanism based on either kinetic exchange and/or Kondo-type interaction combined with the electron correlation effects.Comment: 22 pages, 7 figures, sent to Philosophical Magazin

Professor Zdzisław Hellwig (1925–2013) a Giant in the Renaissance Style

On 8th November 2013, with great sadness we said goodbye to our dear Master and Teacher, Professor Zdzisław Hellwig. He walked away from us forever. Professor Zdzisław Hellwig (1925 – 2013) was a great man with impressive biography. Primarily professor Zdzisław Hellwig was prominent, widely recognized, eminent scholar of international standing in the field of statistics. His most important works are Elements of probability and mathematical statistics, Linear Regression and its applications in economics and Stochastic approximation. On 8th November 2013, with great sadness we said goodbye to our dear Master and Teacher, Professor Zdzisław Hellwig. He walked away from us forever. Professor Zdzisław Hellwig (1925 – 2013) was a great man with impressive biography. Primarily professor Zdzisław Hellwig was prominent, widely recognized, eminent scholar of international standing in the field of statistics. His most important works are Elements of probability and mathematical statistics, Linear Regression and its applications in economics and Stochastic approximation. His second field of achievements was econometrics. The rich scientific achievements in the field of econometrics of Professor Zdzisław Hellwig cover numerous studies dealing with the theory and application, including modeling of the socio – economic development, economic forecasting, and multidimensional comparative analysis and taxsonometrics. Professor Zdzisław Hellwig has a standing as economist. Professor Zdzisław Hellwig is a precursor of research in the field referred to as sustainable development, and early warning system for the national economy. He is considered pioneer of computer science in Poland. His international activities gave him the global scholar rank. Professor Zdzisław Hellwig was exceptionally gifted teacher and educator with long list of prominent followers. He has notable achievements as an organizer. Achievements of Professor Zdzisław Hellwig were widely acknowledged, both in the home university, countywide and abroad.

Theory of Unconventional Superconductivity in Strongly Correlated Systems: Real Space Pairing and Statistically Consistent Mean-Field Theory - in Perspective

In this brief overview we discuss the principal features of real space pairing as expressed via corresponding low-energy (t-J or periodic Anderson-Kondo) effective Hamiltonian, as well as consider concrete properties of those unconventional superconductors. We also rise the basic question of statistical consistency within the so-called renormalized mean-field theory. In particular, we provide the phase diagrams encompassing the stable magnetic and superconducting states. We interpret real space pairing as correlated motion of fermion pair coupled by short-range exchange interaction of magnitude J comparable to the particle renormalized band energy $\sim tx$, where $x$ is the carrier number per site. We also discuss briefly the difference between the real-space and the paramagnon - mediated sources of superconductivity. The paper concentrates both on recent novel results obtained in our research group, as well as puts the theoretical concepts in a conceptual as well as historical perspective. No slave-bosons are required to formulate the present approach

Contribution to bee fauna (Hymenoptera, Apoidea) of Poland. IV

Hyleus lepidulus Cockerell and Eucera pollinosa Smith (= E. polonica Ruszkowski, syn. nov.) are recorded for the first time from Poland. New records of further 5 rare species are given.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę

Touristically-attractive springs in the polish lowlands

On the basis of available published materials and his own research, the author identifies the 27 most attractive springs in the Polish Lowlands. He describes their most important landscape and tourism assets - the relief of the spring outlet area, landforms, the character of the spring itself and the accompanying tourism infrastructure. The article presents available data regarding the water discharged by the springs: volume, temperature, colour and medicinal properties; as well as pointing to associated interesting natural features, examples of religious architecture and historical curiosities. The distribution of springs in the Polish Lowlands is uneven, with the majority found in the area of the morainic uplands, as well as in deeper river valleys and lake troughsNa podstawie materiałów opublikowanych i własnych badań wyszczególniono 27 źródeł na niżu polskim najbardziej atrakcyjnych pod względem turystycznym. Opisano najważniejsze ich walory krajobrazowe i turystyczne – rzeźba miejsca wypływu wody, rodzaj utworów, charakter obudowania źródła i towarzysząca im infrastruktura turystyczna. W miarę możliwości podawano także wydajność źródła, temperaturę wody, jej kolor, właściwości lecznicze oraz zwrócono uwagę na ciekawe obiekty przyrodnicze, obiekty kultu religijnego i ciekawostki historyczne związane ze źródłem. Rozmieszczenie tych źródeł na niżu polskim jest nierównomierne. Najwięcej ich występuje w rejonie wysoczyzn morenowych oraz w głęboko wciętych dolinach rzecznych i rynnach jezior

Openness and competitiveness of economies of the East European countries and the former Soviet Union

In the contemporary world the development of every country is based not only on the utilization of domestic factors but also, on a larger and larger scale, on external factors. The basic prerequisites for their effective use are the openness of a given economy and its competitiveness. In the present study these problems are discussed, and information on the degree of openness and competitiveness of the East European countries and the former Soviet Union (for short EE countries) is given.