One of the main challenges in molecular dynamics is overcoming the ‘timescale barrier’: in many realistic molecular systems, biologically important rare transitions occur on timescales that are not accessible to direct numerical simulation, even on the largest or specifically dedicated supercomputers. This article discusses how to circumvent the timescale barrier by a collection of transfer operator-based techniques that have emerged from dynamical systems theory, numerical mathematics and machine learning over the last two decades. We will focus on how transfer operators can be used to approximate the dynamical behaviour on long timescales, review the introduction of this approach into molecular dynamics, and outline the respective theory, as well as the algorithmic development, from the early numerics-based methods, via variational reformulations, to modern data-based techniques utilizing and improving concepts from machine learning. Furthermore, its relation to rare event simulation techniques will be explained, revealing a broad equivalence of variational principles for long-time quantities in molecular dynamics. The article will mainly take a mathematical perspective and will leave the application to real-world molecular systems to the more than 1000 research articles already written on this subject.

The concept of ‘snowclones’ has gained interest in recent research on linguistic creativity and in studies of extravagance and expressiveness in language. However, no clear criteria for identifying snowclones have yet been established, and detailed corpus-based investigations of the phenomenon are still lacking. This paper addresses this research gap in a twofold way. On the one hand, we develop an operational definition of snowclones, arguing that three criteria are decisive: (i) the existence of a lexically fixed source construction; (ii) partial productivity; (iii) ‘extravagant’ formal and/or functional characteristics. On the other hand, we offer an empirical investigation of two patterns that have often been mentioned as examples of snowclones in the previous literature, namely [the mother of all X] and [X BE the new Y]. We use collostructional analysis and distributional semantics to explore the partial productivity of both patterns’ slot fillers. In sum, we argue that the concept of snowclones, if properly defined, can contribute substantially to our understanding of creative language use, especially regarding the question of how social, cultural, and interpersonal factors influence the choice of more or less salient linguistic constructions.

This paper discusses the traceback method, which has been the basis of some influential papers on first language acquisition. The method sets out to demonstrate that many or even all utterances in a test corpus (usually the last two sessions of recording) can be accounted for with the help of recurrent fixed strings (like What’s that?) or frame-and-slot patterns (like [What’s X?]) that can also be identified in the remaining dataset (i.e., the previous sessions of recording). This is taken as evidence that language learning is much more item-based than previously assumed. In the present paper we sketch the development of the method over the last two decades, and discuss its relation to usage-based theory, as well as the cognitive plausibility of its components, and we highlight both its potential and its limitations.

Damascening, defined in this context as the inlay of one metal into a different metal base, is a rare decorative technique in the Early Bronze Age, known only from seven bronze artefacts found north of the Alps. This paper reports on the first thorough scientific examination of one such find, the axe from Thun-Renzenbühl grave no. 1. This interdisciplinary project involving several institutions in Germany and Switzerland investigated the axe by means of neutron radiographic imaging and X-ray microprobe methods, supported by microscopic examination. The result is an attempt to reconstruct the fabrication and decoration process and to reconsider the enigmatic question of the origins of the damascene technique north of the Alps.

Radioactive 26Al, ejected by massive stars through winds and supernova explosions, leads to γ-ray line emission that can serve as a probe of the interstellar environment in and near young star clusters. The ~ 1 Myr decay time of 26Al is long enough to allow transport over significant distances, which can cause substantial angular offsets between γ-ray emission and cluster stars. Details of such offsets are determined by the morphology of the ISM. We discuss observations in Cygnus and Orion, and models based on population synthesis methods.