A Probabilistic Framework for Imitating Human Race Driver Behavior

Understanding and modeling human driver behavior is crucial for advanced vehicle development. However, unique driving styles, inconsistent behavior, and complex decision processes render it a challenging task, and existing approaches often lack variability or robustness. To approach this problem, we propose Probabilistic Modeling of Driver behavior (ProMoD), a modular framework which splits the task of driver behavior modeling into multiple modules. A global target trajectory distribution is learned with Probabilistic Movement Primitives, clothoids are utilized for local path generation, and the corresponding choice of actions is performed by a neural network. Experiments in a simulated car racing setting show considerable advantages in imitation accuracy and robustness compared to other imitation learning algorithms. The modular architecture of the proposed framework facilitates straightforward extensibility in driving line adaptation and sequencing of multiple movement primitives for future research.Comment: updated references [17] and [33]; added journal inf

Free-standing nanolayers based on Ru silicide formation on Si(100)

Free-standing layers of nanoscale thickness are essential in numerous applications but challenging to fabricate for all but a small selection of materials. We report a versatile, chemical-free pathway of exfoliating centimeter-sized free-standing nanolayers from Si(100) with native oxide based on the spontaneous delamination of thin Ru and Ru-based films upon annealing at temperatures as low as 400 °C. Combining results from X-ray photoelectron spectroscopy (XPS), and transmission and scanning electron microscopy (TEM, SEM), we identify that the element Ru, a thin SiO2 layer, and the Si(100) substrate are essential ingredients for the delamination and propose a stress-based mechanism to explain the effect. The diffusion of Si into the layer upon annealing leads to the formation of a Ru-Si compound at the thin-film side of the Ru/Si(100) interface and pyramidal cavities in the Si(100) substrate. Moreover, the uptake of Si results in an increase in layer thickness and the buildup of in-plane compressive stress, which is reduced by local buckling and finally by the separation of the full layer from the substrate at the SiO2-Si(100) interface. The use of a thin Ru-buffer layer allows us to apply this delamination process to produce free-standing nanolayers of Mo and HfMoNbTiZr in this simple, chemical-free, and vacuum-compatible manner. These results indicate the potential of the reported effect for the fabrication of free-standing layers using a wide range of compositions, deposition techniques, and growth conditions below the onset temperature of delamination

Differential regulation of amidase- and formamidase-mediated ammonia production by the Helicobacter pylori fur repressor.

The production of high levels of ammonia allows the human gastric pathogen Helicobacter pylori to survive the acidic conditions in the human stomach. H. pylori produces ammonia through urease-mediated degradation of urea, but it is also able to convert a range of amide substrates into ammonia via its AmiE amidase and AmiF formamidase enzymes. Here data are provided that demonstrate that the iron-responsive regulatory protein Fur directly and indirectly regulates the activity of the two H. pylori amidases. In contrast to other amidase-positive bacteria, amidase and formamidase enzyme activities were not induced by medium supplementation with their respective substrates, acrylamide and formamide. AmiE protein expression and amidase enzyme activity were iron-repressed in H. pylori 26695 but constitutive in the isogenic fur mutant. This regulation was mediated at the transcriptional level via the binding of Fur to the amiE promoter region. In contrast, formamidase enzyme activity was not iron-repressed but was significantly higher in the fur mutant. This effect was not mediated at the transcriptional level, and Fur did not bind to the amiF promoter region. These roles of Fur in regulation of the H. pylori amidases suggest that the H. pylori Fur regulator may have acquired extra functions to compensate for the absence of other regulatory systems

Epistatic interactions can moderate the antigenic effect of substitutions in haemagglutinin of influenza H3N2 virus.

We previously showed that single amino acid substitutions at seven positions in haemagglutinin determined major antigenic change of influenza H3N2 virus. Here, the impact of two such substitutions was tested in 11 representative H3 haemagglutinins to investigate context-dependence effects. The antigenic effect of substitutions introduced at haemagglutinin position 145 was fully independent of the amino acid context of the representative haemagglutinins. Antigenic change caused by substitutions introduced at haemagglutinin position 155 was variable and context-dependent. Our results suggest that epistatic interactions with contextual amino acids in the haemagglutinin can moderate the magnitude of antigenic change

Василь Васильович Тарновський: духовні витоки українського патріотизму та благодійності

Context: Climate change can directly affect habitats within ecological networks, but may also have indirect effects on network quality by inducing land use change. The relative impact of indirect effects of climate change on the quality of ecological networks currently remains largely unknown. Objectives: The objective of this study was to determine the relative impact of direct and indirect effects of climate change on a network of breeding habitat of four meadow bird species (Black-tailed godwit, Common redshank, Eurasian oystercatcher and Northern lapwing) in the Netherlands. Methods: Habitat models were developed that link meadow bird breeding densities to three habitat characteristics that are sensitive to environmental change (landscape openness, land use and groundwater level). These models were used to assess the impact of scenarios of landscape change with and without climate change on meadow bird breeding habitat quality for a case study area in the peat meadow district of the Netherlands. Results: All scenarios led to significantly reduced habitat quality for all species, mainly as a result of conversion of grassland to bioenergy crops, which reduces landscape openness. Direct effects of climate change on habitat quality were largely absent, indicating that especially human adaptation to climate change rather than direct effects of climate change was decisive for the degradation of ecological network quality for breeding meadow birds. Conclusions: We conclude that scenario studies exploring impacts of climate change on ecological networks should incorporate both land use change resulting from human responses to climate change and direct effects of climate change on landscapes

NikR mediates nickel-responsive transcriptional induction of urease expression in Helicobacter pylori

The important human pathogen Helicobacter pylori requires the abundant expression and activity of its urease enzyme for colonization of the gastric mucosa. The transcription, expression, and activity of H. pylori urease were previously demonstrated to be induced by nickel supplementation of growth media. Here it is demonstrated that the HP1338 protein, an ortholog of the Escherichia coli nickel regulatory protein NikR, mediates nickel-responsive induction of urease expression in H. pylori. Mutation of the HP1338 gene (nikR) of H. pylori strain 26695 resulted in significant growth inhibition of the nikR mutant in the presence of supplementation with NiCl(2) at > or =100 microM, whereas the wild-type strain tolerated more than 10-fold-higher levels of NiCl(2). Mutation of nikR did not affect urease subunit expression or urease enzyme activity in unsupplemented growth media. However, the nickel-induced increase in urease subunit expression and urease enzyme activity observed in wild-type H. pylori was absent in the H. pylori nikR mutant. A similar lack of nickel responsiveness was observed upon removal of a 19-bp palindromic sequence in the ureA promoter, as demonstrated by using a genomic ureA::lacZ reporter gene fusion. In conclusion, the H. pylori NikR protein and a 19-bp operator sequence in the ureA promoter are both essential for nickel-responsive induction of urease expression in H. pylori