Shear induced ordering in systems with competing interactions: A machine learning study

When short-range attractions are combined with long-range repulsions in colloidal particle systems, complex microphases can emerge. Here, we study a system of isotropic particles which can form lamellar structures or a disordered fluid phase when temperature is varied. We show that at equilibrium the lamellar structure crystallizes, while out of equilibrium the system forms a variety of structures at different shear rates and temperatures above melting. The shear-induced ordering is analyzed by means of principal component analysis and artificial neural networks, which are applied to data of reduced dimensionality. Our results reveal the possibility of inducing ordering by shear, potentially providing a feasible route to the fabrication of ordered lamellar structures from isotropic particles.Comment: The following article has been accepted by the Journal of Chemical Physics AIP. After it is published, it will be found at https://aip.scitation.org/journal/jc

Stanisław Lem a kwestie wiary

W kolejnym interdyscyplinarnym tomie dokumentującym działalność uniwersyteckiego Ośrodka Badawczego Myśli Chrześcijańskiej zaprezentowano teksty pracowników różnych uczelni: KUL, UKSW, WSD w Łodzi, UW, UMCS oraz UŁ. Prace te stanowią efekt refleksji kręgów akademickich nad relacjami między tytułowymi kategoriami (kultura – myśl – edukacja), podejmowanej z perspektywy różnych dziedzin nauki – teologii, religioznawstwa i literaturoznawstwa. Autorzy odwołują się do wielorakich kontekstów kulturowych świadczących o dialogu Kościoła ze światem kultury i nauki, takich jak: myśl papieska, ekumenizm, teologia piękna i duchowości, inspiracje chrześcijańskie w literaturze, dyskurs religijny. Tytuł tomu zaczerpnięty został z adhortacji papieża Franciszka, który kieruje swoje przesłanie także do kręgów akademickich. W jego przekonaniu zarówno dziedziny nauki, jak i kategorie myślenia mogą stać się narzędziami ewangelizacji, a teologia – pozostawać w dialogu z innymi naukami i ludzkim doświadczeniem

Retoryka jak narzędzie badania naszych myśli: czym jest téchne rhetoriké?

Retoryka jest nie tylko metodologią nauk humanistycznych; jest najważniejszą z nauk, jaką zostawili nam antyczni myśliciele. Określa ona nie tylko metody argumentacji z przesłanek niepewnych, jest nie tylko teorią tekstu, ale przede wszystkim – jest narzędziem do organizowania naszych myśli i przygotowywania tekstów, których celem ma być przekonywanie, ale tak, aby uzyskać wiedzę a nie mniemanie (Kant). Jednakże jak wiemy, język, którym się posługujemy, jest niezwykle zawodny. Ostrzegali przed tym i Platon, i Arystoteles. Zarazem oni zbudowali podwaliny téchne rhetoriké, której kształt systemowy zawdzięczamy Kwintylianowi. Retoryka – jak twierdzili jej zarówno antyczni, jak i współcześni badacze – nie jest słownikiem chwytów (Volkmann); jest raczej analogonem logiki (Volkmann). Jak powiada Wilhelm Windelband, „dzięki gramatyce i retoryce poznaliśmy prawidłowe reguły myślenia”. Autor sięga nie tylko do tradycji badań nad retoryką, ale i nad językiem, głównie odnosząc się do tradycji Koła wiedeńskiego (Der Wiener Kreis). Acz dorobek współczesnego językoznawstwa, a także współczesnych badań nad filozoficznymi podstawami badań nad językiem będą uwzględnione, to jednak perspektywa zarówno wyznaczona przez Immanuela Kanta, jak i badaczy z kręgu Der Wiener Kreis jest dominująca. Celem niniejszego studium jest nie tylko przypomnienie tezy Windelbanda, ale i jej pełniejsze dowiedzenie.Rhetoric is not only a methodology of the humanities; it is the most important science given to us by ancient philosophers. It defines the methods of argumentation from the uncertain, the theory of texts, but more importantly – it is a tool for organizing our thoughts and preparing works which aim for persuasion – getting the knowledge, not the opinion (Kant). However, as we know, the language we use is extremely unreliable. Plato and Aristotle warned us against that. At the same time, they built the foundations of téchne rhetoriké, which systemic shape we owe to Quintilianus. Rhetoric, as both – ancient and modern scholars have claimed, is not a grammar dictionary; it is rather an analogue of logic (Volkmann). As Wilhelm Windelband says: “thanks to grammar and rhetoric we have learned the correct rules of thinking”. The author draws not only from the tradition of research on rhetoric, but also from language theory – mainly referring to the tradition of the Viennese Circle (Der Wiener Kreis). As far as the achievements of contemporary linguistics and contem¬porary research on the philosophical foundations of language research are taken into account – the perspective set by both Immanuel Kant and researchers from the Der Wiener Kreis circle is dominant here. The purpose of this study is not only to remind Windelbad’s thesis, but also to prove it wholistically

Long-term monitoring of a winter bat assemblage revealed large fluctuations and trends in species abundance

Monitoring studies in Strzaliny, one of the greatest hibernacula in Poland, comprised 31 annual bat censuses (1989–2019). The abundance peaked in 2002 for Myotis myotis, 2009 for Myotis nattereri and 2008 for the whole assemblage. Comparison of the maximum abundance in the monitoring period with that from 1980 to 1982 showed an almost fourfold increase for the whole assemblage, tenfold increase for M. nattereri and fourfold increase for M. myotis. In 1989–2019, the numbers of M. myotis, M. nattereri, Myotis daubentonii and Plecotus auritus were fluctuating, but most of the recorded changes could not be explained by methodological problems or a direct human impact. Therefore, the cumulative results largely reflected the real trends in the species abundance. A long-term upward trend in the whole bat assemblage was recognisable, but with a stable or slightly decreasing phase in the last decade. An upward trend in M. nattereri was even stronger and has only slightly flattened recently. In M. myotis, the trend was clearly upwards up to the early 2000s, but weakly downwards in the following years. In M. daubentonii and P. auritus, no significant trend was determined. In strongly fluctuating M. daubentonii, the numbers were mostly moderate or high, and even increasing, up to 2008 and only moderate or low in the following years. In P. auritus, an increase occurred in the 1980s and early 1990s, and then, after the stochastic human-induced drop in 1994, its abundance remained relatively stable. The population trends in Strzaliny largely reflected the general trends assessed for a large part of Europe. This suggests that the general population trends may be recognisable even in one large winter assemblage if it is reliably and consistently monitored through a long period. In this context, the hibernaculum in Strzaliny appeared to be a model object for such studies

Random packing of spheres in Menger sponge

Random packing of spheres inside fractal collectors of dimension 2 < d < 3 is studied numerically using Random Sequential Adsorption (RSA) algorithm. The paper focuses mainly on the measurement of random packing saturation limit. Additionally, scaling properties of density autocorrelations in the obtained packing are analyzed. The RSA kinetics coefficients are also measured. Obtained results allow to test phenomenological relation between random packing saturation density and collector dimension. Additionally, performed simulations together with previously obtained results confirm that, in general, the known dimensional relations are obeyed by systems having non-integer dimension, at least for d < 3.Comment: 13 pages, 6 figure

Legal Fiction

While numerous ancient human DNA datasets from across Europe have been published till date, modern-day Poland in particular, remains uninvestigated. Besides application in the reconstruction of continent-wide human history, data from this region would also contribute towards our understanding of the history of the Slavs, whose origin is hypothesized to be in East or Central Europe. Here, we present the first population-scale ancient human DNA study from the region of modern-day Poland by establishing mitochondrial DNA profiles for 23 samples dated to 200 BC - 500 AD (Roman Iron Age) and for 20 samples dated to 1000-1400 AD (Medieval Age). Our results show that mitochondrial DNA sequences from both periods belong to haplogroups that are characteristic of contemporary West Eurasia. Haplotype sharing analysis indicates that majority of the ancient haplotypes are widespread in some modern Europeans, including Poles. Notably, the Roman Iron Age samples share more rare haplotypes with Central and Northeast Europeans, whereas the Medieval Age samples share more rare haplotypes with East-Central and South-East Europeans, primarily Slavic populations. Our data demonstrates genetic continuity of certain matrilineages (H5a1 and N1a1a2) in the area of present-day Poland from at least the Roman Iron Age until present. As such, the maternal gene pool of present-day Poles, Czechs and Slovaks, categorized as Western Slavs, is likely to have descended from inhabitants of East-Central Europe during the Roman Iron Age

Nonuniversality in level dynamics

Statistical properties of parametric motion in ensembles of Hermitian banded random matrices are studied. We analyze the distribution of level velocities and level curvatures as well as their correlation functions in the crossover regime between three universality classes. It is shown that the statistical properties of level dynamics are in general non-universal and strongly depend on the way in which the parametric dynamics is introduced.Comment: 24 pages + 10 figures (not included, avaliable from the author), submitted to Phys. Rev.

Quantum magnetism in the stripe phase: bond- versus site order

It is argued that the spin dynamics in the charge-ordered stripe phase might be revealing with regards to the nature of the anomalous spin dynamics in cuprate superconductors. Specifically, if the stripes are bond ordered much of the spin fluctuation will originate in the spin sector itself, while site ordered stripes require the charge sector as the driving force for the strong quantum spin fluctuations.Comment: 4 pages, 3 figures, LaTe

Spontaneous emission of non-dispersive Rydberg wave packets

Non dispersive electronic Rydberg wave packets may be created in atoms illuminated by a microwave field of circular polarization. We discuss the spontaneous emission from such states and show that the elastic incoherent component (occuring at the frequency of the driving field) dominates the spectrum in the semiclassical limit, contrary to earlier predictions. We calculate the frequencies of single photon emissions and the associated rates in the "harmonic approximation", i.e. when the wave packet has approximately a Gaussian shape. The results agree well with exact quantum mechanical calculations, which validates the analytical approach.Comment: 14 pages, 4 figure