We establish constraints on the dimension-six four-heavy-quark operators in the Standard Model Effective Field Theory (SMEFT) by synthesising LHC measurements of top-quark and single-Higgs production with electroweak precision observables. We scrutinise the choice of the γ_5 scheme in single-Higgs calculations, demonstrating its non-negligible impact on SMEFT fits.
In most prediction and estimation situations, scientists consider various statistical models for the same problem, and naturally want to select amongst the best. Hansen et al. (2011) provide a powerful solution to this problem by the so-called model confidence set, a subset of the original set of available models that contains the best models with a given level of confidence. Importantly, model confidence sets respect the underlying selection uncertainty by being flexible in size. However, they presuppose a fixed sample size which stands in contrast to the fact that model selection and forecast evaluation are inherently sequential tasks where we successively collect new data and where the decision to continue or conclude a study may depend on the previous outcomes. In this article, we extend model confidence sets sequentially over time by relying on sequential testing methods. Recently, e-processes and confidence sequences have been introduced as new, safe methods for assessing statistical evidence. Sequential model confidence sets allow to continuously monitor the models' performances and come with time-uniform, nonasymptotic coverage guarantees.
Refractory compositionally complex alloys (RCCAs) are known for their exceptional high-temperature resistance. However, their inherent brittleness at room temperature limits broader practical applications. To explore the effects of microstructure and loading conditions on their deformation behavior, micromechanical experiments, including microbending and micropillar compression tests, were performed on two representative RCCAs: equimolar NbMoCrTiAl (ordered B2 crystal structure) and TaNbHfZrTi (disordered A2 crystal structure). Both alloys demonstrated significant plastic deformation, with strains exceeding 40% at room temperature. Despite prior reports of limited ductility in NbMoCrTiAl at the millimeter scale, our micropillar compression tests on single-crystalline pillars oriented along (100) and (110) reveal substantial plasticity. The dominant deformation mechanisms in NbMoCrTiAl were identified as crystallographic slip and cross-slip of screw dislocations. By contrast, TaNbHfZrTi exhibited a broader range of mechanisms, including screw dislocation slip and a high density of non-screw dislocations, accompanied by kink band formation and activation of high-order slip planes, which collectively contribute to its remarkable ductility among the highest reported for body-centered cubic RCCAs. The atomic size mismatch inherent in compositionally complex alloys enhances dislocation mobility, while the random distribution of elements promotes the formation of edge segments, further improving ductility. These findings highlight the critical role of microstructural characteristics in tailoring the deformation behavior of RCCAs for room-temperature applications.
The correlation of space- and time-resolved measurements of catalytic activity with catalyst state is an invaluable tool to advance the understanding and development of complex catalytic systems under conditions relevant to technical applications. Such an approach is employed here to investigate the catalytic deactivation in the reduction of NO by CO over Pt/Al2O3 on freshly reduced catalysts in a channel reactor and at concentrations typical for emission control. Planar laser-induced fluorescence (PLIF) is used to visualize the 2D concentration profiles and to derive space- and time-resolved NO conversion rates for different CO/NO ratios, temperatures and mass flow rates. The changes in catalytic activity are correlated with temporal and spatial changes in oxidation state determined by operando X-ray absorption spectroscopy (XAS) under the same conditions. The time scales of the changes in catalytic activity depend not only on the stoichiometry and temperature, but also on the position along the catalyst channel and differ significantly from the temporal changes of the oxidation state. The different time scales are discussed in the context of the known CO poisoning as well as the formation and storage of isocyanate on the support. Isocyanate formation temporarily counteracting CO poisoning could explain the differences in the observed time scales under different reaction conditions and at different locations on the catalyst.
High-resolution multistatic imaging radar systems pose significant challenges to the employed synchronization schemes, as such radar networks need to operate coherently. Especially high-resolution systems operating at a high center frequency push the required synchronization requirements into the single-digit picosecond regime. Within the project Imaging of Satellites in Space-Next Generation (IoSiS-NG), the task at hand is further challenged by the use of far baselines, where commonly seen approaches fail, as no line-of-sight (LOS) free-space propagation or wired method can be employed. In this article, a robust synchronization method is presented that elevates well-established global navigation satellite systems (GNSSs)-based methods by about three orders of magnitude through the coordinated reception of non-cooperative (NC) signals at all participating nodes. Exploiting the identical signal payload at all stations, the timing and phase differences of the nodes can be tracked and corrected in the post-processing stage. Here, we demonstrate our newly developed algorithm, simulative studies and real-world experiments using satellite broadcast television (TV) signals as NC signals to synchronize a high-resolution imaging radar achieving a timing standard deviation of less than 1.8 ps and a phase coherence for the X-band radar of less than 2 degrees allowing interferometric or tomographic imaging principles to be used.
