Stochastic modeling of cargo transport by teams of molecular motors

Many different types of cellular cargos are transported bidirectionally along microtubules by teams of molecular motors. The motion of this cargo-motors system has been experimentally characterized in vivo as processive with rather persistent directionality. Different theoretical approaches have been suggested in order to explore the origin of this kind of motion. An effective theoretical approach, introduced by M\"uller et al., describes the cargo dynamics as a tug-of-war between different kinds of motors. An alternative approach has been suggested recently by Kunwar et al., who considered the coupling between motor and cargo in more detail. Based on this framework we introduce a model considering single motor positions which we propagate in continuous time. Furthermore, we analyze the possible influence of the discrete time update schemes used in previous publications on the system's dynamic.Comment: Cenference proceedings - Traffic and Granular Flow 1

A conserved role for Snail as a potentiator of active transcription

The transcription factors of the Snail family are key regulators of epithelial-mesenchymal transitions, cell morphogenesis, and tumor metastasis. Since its discovery in Drosophila ~25 years ago, Snail has been extensively studied for its role as a transcriptional repressor. Here we demonstrate that Drosophila Snail can positively modulate transcriptional activation. By combining information on in vivo occupancy with expression profiling of hand-selected, staged snail mutant embryos, we identified 106 genes that are potentially directly regulated by Snail during mesoderm development. In addition to the expected Snail-repressed genes, almost 50% of Snail targets showed an unanticipated activation. The majority of "Snail-activated" genes have enhancer elements cobound by Twist and are expressed in the mesoderm at the stages of Snail occupancy. Snail can potentiate Twist-mediated enhancer activation in vitro and is essential for enhancer activity in vivo. Using a machine learning approach, we show that differentially enriched motifs are sufficient to predict Snail's regulatory response. In silico mutagenesis revealed a likely causative motif, which we demonstrate is essential for enhancer activation. Taken together, these data indicate that Snail can potentiate enhancer activation by collaborating with different activators, providing a new mechanism by which Snail regulates development

Gamma-induced background in the KATRIN main spectrometer

International audienceThe KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c 2 . It investigates the kinematics of β -particles from tritium β -decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about 12% of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than 17% (90% confidence level) of the overall MS background

The design, construction, and commissioning of the KATRIN experiment

The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Anomaly indicators for Kaplan turbine components based on patterns of normal behavior

This paper describes and proposes some indicators for continuous monitoring of anomalous conditions in the hydraulic system of a Kaplan turbine using SCADA data. The indicators are based on significant deviations between the estimated values for key variables describing the current working conditions of the components at the plant, and those actually observed. This monitoring strategy requires models describing the expected values for variables through the whole range of possible working conditions of the monitored components. These models are normal behavior models able to characterize the typical relationships between a set of variables used as inputs to the models and the corresponding output of a target variable whose expected value has to be predicted. The criteria to select the variables to use in the models are based on the physical working principles of the component. The paper is focused on models of normal behavior applied to a real case of condition monitoring of a Kaplan turbine regulating mechanism

Anomaly indicators for Kaplan turbine components based on patterns of normal behavior

This paper describes and proposes some indicators for continuous monitoring of anomalous conditions in the hydraulic system of a Kaplan turbine using SCADA data. The indicators are based on significant deviations between the estimated values for key variables describing the current working conditions of the components at the plant, and those actually observed. This monitoring strategy requires models describing the expected values for variables through the whole range of possible working conditions of the monitored components. These models are normal behavior models able to characterize the typical relationships between a set of variables used as inputs to the models and the corresponding output of a target variable whose expected value has to be predicted. The criteria to select the variables to use in the models are based on the physical working principles of the component. The paper is focused on models of normal behavior applied to a real case of condition monitoring of a Kaplan turbine regulating mechanism.Anomaly indicators for Kaplan turbine components based on patterns of normal behaviorpublishedVersio