TY - JOUR AB - We present a numerical analysis of spin-1/2 fermions in a one-dimensional harmonic potential in the presence of a magnetic point-like impurity at the center of the trap. The model represents a few-body analogue of a magnetic impurity in the vicinity of an s-wave superconductor. Already for a few particles we find a ground-state level crossing between sectors with different fermion parities. We interpret this crossing as a few-body precursor of a quantum phase transition, which occurs when the impurity "breaks" a Cooper pair. This picture is further corroborated by analyzing density-density correlations in momentum space. Finally, we discuss how the system may be realized with existing cold-atoms platforms. AU - Rammelmüller, Lukas AU - Huber, David AU - Čufar, Matija AU - Brand, Joachim AU - Hammer, Hans-Werner AU - Volosniev, Artem ID - 13278 IS - 1 JF - SciPost Physics KW - General Physics and Astronomy SN - 2542-4653 TI - Magnetic impurity in a one-dimensional few-fermion system VL - 14 ER - TY - JOUR AB - Viscous flows through pipes and channels are steady and ordered until, with increasing velocity, the laminar motion catastrophically breaks down and gives way to turbulence. How this apparently discontinuous change from low- to high-dimensional motion can be rationalized within the framework of the Navier-Stokes equations is not well understood. Exploiting geometrical properties of transitional channel flow we trace turbulence to far lower Reynolds numbers (Re) than previously possible and identify the complete path that reversibly links fully turbulent motion to an invariant solution. This precursor of turbulence destabilizes rapidly with Re, and the accompanying explosive increase in attractor dimension effectively marks the transition between deterministic and de facto stochastic dynamics. AU - Paranjape, Chaitanya S AU - Yalniz, Gökhan AU - Duguet, Yohann AU - Budanur, Nazmi B AU - Hof, Björn ID - 13274 IS - 3 JF - Physical Review Letters KW - General Physics and Astronomy SN - 0031-9007 TI - Direct path from turbulence to time-periodic solutions VL - 131 ER - TY - JOUR AB - Chromosomes in the eukaryotic nucleus are highly compacted. However, for many functional processes, including transcription initiation, the pairwise motion of distal chromosomal elements such as enhancers and promoters is essential and necessitates dynamic fluidity. Here, we used a live-imaging assay to simultaneously measure the positions of pairs of enhancers and promoters and their transcriptional output while systematically varying the genomic separation between these two DNA loci. Our analysis reveals the coexistence of a compact globular organization and fast subdiffusive dynamics. These combined features cause an anomalous scaling of polymer relaxation times with genomic separation leading to long-ranged correlations. Thus, encounter times of DNA loci are much less dependent on genomic distance than predicted by existing polymer models, with potential consequences for eukaryotic gene expression. AU - Brückner, David AU - Chen, Hongtao AU - Barinov, Lev AU - Zoller, Benjamin AU - Gregor, Thomas ID - 13261 IS - 6652 JF - Science TI - Stochastic motion and transcriptional dynamics of pairs of distal DNA loci on a compacted chromosome VL - 380 ER - TY - GEN AU - Kleshnina, Maria ID - 13336 TI - kleshnina/stochgames_info: The effect of environmental information on evolution of cooperation in stochastic games ER - TY - JOUR AB - The ages of solar-like stars have been at the center of many studies such as exoplanet characterization or Galactic-archeology. While ages are usually computed from stellar evolution models, relations linking ages to other stellar properties, such as rotation and magnetic activity, have been investigated. With the large catalog of 55,232 rotation periods, Prot, and photometric magnetic activity index, Sph from Kepler data, we have the opportunity to look for such magneto-gyro-chronology relations. Stellar ages are obtained with two stellar evolution codes that include treatment of angular momentum evolution, hence using Prot as input in addition to classical atmospheric parameters. We explore two different ways of predicting stellar ages on three subsamples with spectroscopic observations: solar analogs, late-F and G dwarfs, and K dwarfs. We first perform a Bayesian analysis to derive relations between Sph and ages between 1 and 5 Gyr, and other stellar properties. For late-F and G dwarfs, and K dwarfs, the multivariate regression favors the model with Prot and Sph with median differences of 0.1% and 0.2%, respectively. We also apply Machine Learning techniques with a Random Forest algorithm to predict ages up to 14 Gyr with the same set of input parameters. For late-F, G and K dwarfs together, predicted ages are on average within 5.3% of the model ages and improve to 3.1% when including Prot. These are very promising results for a quick age estimation for solar-like stars with photometric observations, especially with current and future space missions. AU - Mathur, Savita AU - Claytor, Zachary R. AU - Santos, Ângela R. G. AU - García, Rafael A. AU - Amard, Louis AU - Bugnet, Lisa Annabelle AU - Corsaro, Enrico AU - Bonanno, Alfio AU - Breton, Sylvain N. AU - Godoy-Rivera, Diego AU - Pinsonneault, Marc H. AU - van Saders, Jennifer ID - 13443 IS - 2 JF - The Astrophysical Journal KW - Space and Planetary Science KW - Astronomy and Astrophysics SN - 0004-637X TI - Magnetic activity evolution of solar-like stars. I. Sph–age relation derived from Kepler observations VL - 952 ER -