Changes in the flagellar bundling time account for variations in swimming behavior of flagellated bacteria in viscous media

Although the motility of the flagellated bacteria, Escherichia coli, has been widely studied, the effect of viscosity on swimming speed remains controversial. The swimming mode of wild-type E.coli is often idealized as a "run-and- tumble" sequence in which periods of swimming at a constant speed are randomly interrupted by a sudden change of direction at a very low speed. Using a tracking microscope, we follow cells for extended periods of time in Newtonian liquids of varying viscosity, and find that the swimming behavior of a single cell can exhibit a variety of behaviors including run-and-tumble and "slow-random-walk" in which the cells move at relatively low speed. Although the characteristic swimming speed varies between individuals and in different polymer solutions, we find that the skewness of the speed distribution is solely a function of viscosity and can be used, in concert with the measured average swimming speed, to determine the effective running speed of each cell. We hypothesize that differences in the swimming behavior observed in solutions of different viscosity are due to changes in the flagellar bundling time, which increases as the viscosity rises, due to the lower rotation rate of the flagellar motor. A numerical simulation and the use of Resistive Force theory provide support for this hypothesis

Compatibility and noncontextuality for sequential measurements

A basic assumption behind the inequalities used for testing noncontextual hidden variable models is that the observables measured on the same individual system are perfectly compatible. However, compatibility is not perfect in actual experiments using sequential measurements. We discuss the resulting "compatibility loophole" and present several methods to rule out certain hidden variable models which obey a kind of extended noncontextuality. Finally, we present a detailed analysis of experimental imperfections in a recent trapped ion experiment and apply our analysis to that case.Comment: 15 pages, 2 figures, v2: problem with latex solve

Thermally activated diffusion and lattice relaxation in (Si)GeSn materials

Germanium-tin (GeSn) alloys have emerged as a promising material for future optoelectronics, energy harvesting, and nanoelectronics owing to their direct band gap and compatibility with existing Si-based electronics. Yet, their metastability poses significant challenges calling for in-depth investigations of their thermal behavior. With this perspective, this work addresses the interdiffusion processes throughout thermal annealing of pseudomorphic GeSn binary and SiGeSn ternary alloys. In both systems, the initially pseudomorphic layers are relaxed upon annealing exclusively via thermally induced diffusional mass transfer of Sn. Systematic postgrowth annealing experiments reveal enhanced Sn and Si diffusion regimes that manifest at temperatures below 650 °C. The amplified low-temperature diffusion and the observation of only subtle differences between binary and ternary hint at the unique metastability of the Si-Ge-Sn material system as the most important driving force for phase separation

EoCoE Performance Benchmarking Methodology for Renewable Energy Applications

The global transition away from fossil fuels towards a sustainable, decarbonized energy ecosystem will rely heavily on digitization to drive necessary innovations in production and storage technologies, mitigate power source intermittency and manage its distribution via a complex grid hierarchy. At the same time, supercomputing is also experiencing a major paradigm shift: future exascale technologies will open up unprecedented opportunities to tackle complex physical problems – such as the design of wind farms or smart materials for photovoltaics and batteries – but will demand major restructuring of application software, numerical algorithms and programming models. These challenges motivated the creation of the Energy Oriented Centre of Excellence (EoCoE) two years ago; an EU-funded consortium twenty-one partners across eight countries with strong engagements in both the HPC and energy fields.This poster presents an optimisation strategy developed by the Energy Oriented Centre of Excellence (EoCoE) for computational models used in a variety of renewable energy domains. It is found that typical applications in this comparatively new sector cover the widest possible range of HPC maturity, from simple parallelization needs to near-exascale readiness. A key part of this process has therefore been the quantitative, reproducible performance assessment of applications consolidated by follow-up actions by code-teams comprising members of both developer groups and HPC centres involved with the EoCoE consortium. Examples of early successes achieved with this practice are given, together with an outlook on challenges faced for energy applications with next-generation, pre-exascale architectures

The Complement Control-Related Genes CSMD1 and CSMD2 Associate to Schizophrenia

Patients with schizophrenia often suffer from cognitive dysfunction, including impaired learning and memory. We recently demonstrated that long-term potentiation in rat hippocampus, a mechanistic model of learning and memory, is linked to gene expression changes in immunity-related processes involved in complement activity and antigen presentation. We therefore aimed to examine whether key regulators of these processes are genetic susceptibility factors in schizophrenia.Analysis of genetic association was based on data mining of genotypes from a German genome-wide association study and a multiplex GoldenGate tag single nucleotide polymorphism (SNP)-based assay of Norwegian and Danish case-control samples (Scandinavian Collaboration on Psychiatric Etiology), including 1133 patients with schizophrenia and 2444 healthy control subjects.Allelic associations were found across all three samples for eight common SNPs in the complement control-related gene CSMD2 (CUB and Sushi Multiple Domains 2) on chromosome 1p35.1-34.3, of which rs911213 reached a statistical significance comparable to that of a genome wide threshold (p value = 4.0 × 10(-8); odd ratio = .73, 95% confidence interval = .65-.82). The second most significant gene was CSMD1 on chromosome 8p23.2, a homologue to CSMD2. In addition, we observed replicated associations in the complement surface receptor CD46 as well as the major histocompatibility complex genes HLA-DMB and HLA-DOA.These data demonstrate a significant role of complement control-related genes in the etiology of schizophrenia and support disease mechanisms that involve the activity of immunity-related pathways in the brain