Anomalous Expansion of Attractively Interacting Fermionic Atoms in an Optical Lattice

Strong correlations can dramatically modify the thermodynamics of a quantum many-particle system. Especially intriguing behaviour can appear when the system adiabatically enters a strongly correlated regime, for the interplay between entropy and strong interactions can lead to counterintuitive effects. A well known example is the so-called Pomeranchuk effect, occurring when liquid 3He is adiabatically compressed towards its crystalline phase. Here, we report on a novel anomalous, isentropic effect in a spin mixture of attractively interacting fermionic atoms in an optical lattice. As we adiabatically increase the attraction between the atoms we observe that the gas, instead of contracting, anomalously expands. This expansion results from the combination of two effects induced by pair formation in a lattice potential: the suppression of quantum fluctuations as the attraction increases, which leads to a dominant role of entropy, and the progressive loss of the spin degree of freedom, which forces the gas to excite additional orbital degrees of freedom and expand to outer regions of the trap in order to maintain the entropy. The unexpected thermodynamics we observe reveal fundamentally distinctive features of pairing in the fermionic Hubbard model.Comment: 6 pages (plus appendix), 6 figure

Systems toxicology to advance human and environmental hazard assessment : A roadmap for advanced materials

Ideally, a Systems Toxicology (ST) approach is aimed at by (eco)toxicologists, i.e. a multidisciplinary area incorporating classical toxicological concepts with omics technologies, and the understanding of this through computational data sciences, chemistry, mathematics, and physics modelling. As outlined in sev-eral public reports (e.g. from ECHA-European Chemical Agency and EFSA-European Food Safety Authority), the way forward in the coming years in Europe is to integrate New Approach Methodologies (NAMs) (in-cluding omics technologies) into hazard and hence risk assessment (RA). Adverse Outcome Pathways (AOPs) describe a sequence of events in response to stress, from the molecular initiating event until an adverse outcome, which is relevant to RA or regulatory decision-making. AOPs are one of the facilitators to integrate mechanistic data into RA, but it is urgent to increase the inclusion of the vast mechanistic knowledge available, especially for the RA of novel smart and advanced materials (AdMa) with multi-functional characteristics. There are still many challenges to the routine usage of NAMs, e.g. omics-based information. Here, we summarise the current state of the art of ST, the benefits of human and environ-mental health cross knowledge and the available methods and output. The importance of this area has been highlighted for many years but is even more pressing in the context of AdMa. Furthermore, we outline the challenges and suggest recommendations for future implementation.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Nonquantum Gravity

One of the great challenges for 21st century physics is to quantize gravity and generate a theory that will unify gravity with the other three fundamental forces of nature. This paper takes the (heretical) point of view that gravity may be an inherently classical, i.e., nonquantum, phenomenon and investigates the experimental consequences of such a model. At present there is no experimental evidence of the quantum nature of gravity and the liklihood of definitive tests in the future is not at all certain. If gravity is, indeed, a nonquantum phenomenon, then it is suggested that evidence will most likely appear at mesoscopic scales.Comment: essentially the same as the version that appears in Foundations of Physics, 39, 331 (2009

RNAcontext: A New Method for Learning the Sequence and Structure Binding Preferences of RNA-Binding Proteins

Metazoan genomes encode hundreds of RNA-binding proteins (RBPs). These proteins regulate post-transcriptional gene expression and have critical roles in numerous cellular processes including mRNA splicing, export, stability and translation. Despite their ubiquity and importance, the binding preferences for most RBPs are not well characterized. In vitro and in vivo studies, using affinity selection-based approaches, have successfully identified RNA sequence associated with specific RBPs; however, it is difficult to infer RBP sequence and structural preferences without specifically designed motif finding methods. In this study, we introduce a new motif-finding method, RNAcontext, designed to elucidate RBP-specific sequence and structural preferences with greater accuracy than existing approaches. We evaluated RNAcontext on recently published in vitro and in vivo RNA affinity selected data and demonstrate that RNAcontext identifies known binding preferences for several control proteins including HuR, PTB, and Vts1p and predicts new RNA structure preferences for SF2/ASF, RBM4, FUSIP1 and SLM2. The predicted preferences for SF2/ASF are consistent with its recently reported in vivo binding sites. RNAcontext is an accurate and efficient motif finding method ideally suited for using large-scale RNA-binding affinity datasets to determine the relative binding preferences of RBPs for a wide range of RNA sequences and structures

Post-transcriptional control during chronic inflammation and cancer: a focus on AU-rich elements

A considerable number of genes that code for AU-rich mRNAs including cytokines, growth factors, transcriptional factors, and certain receptors are involved in both chronic inflammation and cancer. Overexpression of these genes is affected by aberrations or by prolonged activation of several signaling pathways. AU-rich elements (ARE) are important cis-acting short sequences in the 3′UTR that mediate recognition of an array of RNA-binding proteins and affect mRNA stability and translation. This review addresses the cellular and molecular mechanisms that are common between inflammation and cancer and that also govern ARE-mediated post-transcriptional control. The first part examines the role of the ARE-genes in inflammation and cancer and sequence characteristics of AU-rich elements. The second part addresses the common signaling pathways in inflammation and cancer that regulate the ARE-mediated pathways and how their deregulations affect ARE-gene regulation and disease outcome