Temporal evolution of features that control 10-m wind gusts in moist baroclinic wave simulations identified using non-linear regression

EMS Annual Meeting Abstracts, Vol. 19A majority of insured losses over Europe are related to Extra-Tropical Cyclones (ETC) which are characterised by strong winds, heavy precipitation and powerful ocean waves. Baroclinic wave simulations (BWS) are used to study ETC by varying their background state and measuring their different intensities. However, two main issues limit an exhaustive exploration of ETC intensity and background state relationship: 1) the dimensionality of the feature space, 2) a large number of intensity measures. To alleviate this issue, this study proposes to use a wrapper Feature Selection Algorithm (wFSA) combined with a non-linear regressor applied to an intensity measure. The selected subsets are analysed through time. BWS was performed in the moist case using OpenIFS version Cy43r3v2 configured as an aqua planet with full physics and the radiation scheme deactivated. The atmospheric state proposed by Jablonowski and Williamson was used. The spatial resolution of the simulation was set to TL319/L137 and the time resolution to 20 minutes for 15 days. The initial perturbation was located in 40°N 20°E. A number of 55 measures -called features- were extracted from the BWS and the 10-m wind gust was selected as the intensity measure. A stable wFSA was performed using weighted Random Forest Regressor in the framework proposed by Meinshausen and Bühlmann. The regression was run 10 times on 60% of randomly selected points in the northern hemisphere to infer the 10-m wind gust. Finally, the average feature importance and its variance were computed for each feature every 12 hours. The forecast surface roughness and the specific humidity were the most important features for the first 2 days. Afterwards, mean sea level pressure became predominant for 5 days. For the remaining days, forecast surface roughness, specific humidity and large scale precipitation were the most important features to infer 10-m wind gust. Further work will aim at increasing the number of BWS by modifying the average temperature of the background state. All results will be compared to propose an efficient dimension reduction to study BWS and their evolution.Peer reviewe

Relationships between extra-tropical cyclone intensity measures

EMS Annual Meeting Abstracts, Vol. 19Extra-Tropical Cyclones (ETC) cause the most variability in weather and a significant portion of total insured losses in Europe. Their impacts are caused by high wind speeds, heavy precipitation and large ocean waves. The intensity of ETCs can be quantified with multiple different measures such as Mean Sea Level Pressure (MSLP), relative vorticity or storm severity indices. Currently, it is not known how the various measures of ETC intensity relate to each other. The aim of this study is to determine relationships between different intensity measures, their dependence on geographical region, and on the structure and evolution of the ETCs. ERA5 reanalysis data from 1979 to 2021 was used to study the relationships. The analysis was restricted to the cold season (from October to March) which is when the strongest ETCs most often occur. ETCs were tracked using feature tracking software TRACK with values of 850-hPa relative vorticity every three hours as input. To focus on the most relevant ETCs affecting Europe, only tracks in the North Atlantic were chosen and stationary and short-lived systems were excluded. The intensity measures were calculated by combining the ETC tracks with parameters from ERA5 reanalysis. The intensity measures analysed include the maximum 850-hPa relative vorticity, minimum MSLP, maximum wind gusts, and a storm severity index which is based on extreme 10-metre winds and their occurrence probability. Relationships between different intensity measures were analysed for land and sea areas separately using mutual information and density heatmaps.    The initial results shows that there is a correlation between maximum 850-hPa vorticity and minimum MSLP, and that this correlation is stronger over sea than land areas. However, this relationship is non-linear, with considerable spread associated with it. Additional results concerning the other measures of intensity will also be presented.Extra-Tropical Cyclones (ETC) cause the most variability in weather and a significant portion of total insured losses in Europe. Their impacts are caused by high wind speeds, heavy precipitation and large ocean waves. The intensity of ETCs can be quantified with multiple different measures such as Mean Sea Level Pressure (MSLP), relative vorticity or storm severity indices. Currently, it is not known how the various measures of ETC intensity relate to each other. The aim of this study is to determine relationships between different intensity measures, their dependence on geographical region, and on the structure and evolution of the ETCs. ERA5 reanalysis data from 1979 to 2021 was used to study the relationships. The analysis was restricted to the cold season (from October to March) which is when the strongest ETCs most often occur. ETCs were tracked using feature tracking software TRACK with values of 850-hPa relative vorticity every three hours as input. To focus on the most relevant ETCs affecting Europe, only tracks in the North Atlantic were chosen and stationary and short-lived systems were excluded. The intensity measures were calculated by combining the ETC tracks with parameters from ERA5 reanalysis. The intensity measures analysed include the maximum 850-hPa relative vorticity, minimum MSLP, maximum wind gusts, and a storm severity index which is based on extreme 10-metre winds and their occurrence probability. Relationships between different intensity measures were analysed for land and sea areas separately using mutual information and density heatmaps.    The initial results shows that there is a correlation between maximum 850-hPa vorticity and minimum MSLP, and that this correlation is stronger over sea than land areas. However, this relationship is non-linear, with considerable spread associated with it. Additional results concerning the other measures of intensity will also be presented.Peer reviewe

Stochastic Adversarial Gradient Embedding for Active Domain Adaptation

Unsupervised Domain Adaptation (UDA) aims to bridge the gap between a source domain, where labelled data are available, and a target domain only represented with unlabelled data. If domain invariant representations have dramatically improved the adaptability of models, to guarantee their good transferability remains a challenging problem. This paper addresses this problem by using active learning to annotate a small budget of target data. Although this setup, called Active Domain Adaptation (ADA), deviates from UDA's standard setup, a wide range of practical applications are faced with this situation. To this purpose, we introduce \textit{Stochastic Adversarial Gradient Embedding} (SAGE), a framework that makes a triple contribution to ADA. First, we select for annotation target samples that are likely to improve the representations' transferability by measuring the variation, before and after annotation, of the transferability loss gradient. Second, we increase sampling diversity by promoting different gradient directions. Third, we introduce a novel training procedure for actively incorporating target samples when learning invariant representations. SAGE is based on solid theoretical ground and validated on various UDA benchmarks against several baselines. Our empirical investigation demonstrates that SAGE takes the best of uncertainty \textit{vs} diversity samplings and improves representations transferability substantially

Topological surface states of strained Mercury-Telluride probed by ARPES

The topological surface states of strained HgTe have been measured using high-resolution ARPES measurements. The dispersion of surface states form a Dirac cone, which origin is close to the top of the \ghh band: the top half of the Dirac cone is inside the stress-gap while the bottom half lies within the heavy hole bands and keeps a linear dispersion all the way to the X-point. The circular dichroism of the photo-emitted electron intensity has also been measured for all the bands.Comment: with supplementary materia

Strained HgTe: a textbook 3D topological insulator

Topological insulators can be seen as band-insulators with a conducting surface. The surface carriers are Dirac particles with an energy which increases linearly with momentum. This confers extraordinary transport properties characteristic of Dirac matter, a class of materials which electronic properties are "graphene-like". We show how HgTe, a material known to exhibit 2D spin-Hall effect in thin quantum wells,\cite{Konig2007} can be turned into a textbook example of Dirac matter by opening a strain-gap by exploiting the lattice mismatch on CdTe-based substrates. The evidence for Dirac matter found in transport shows up as a divergent Hall angle at low field when the chemical potential coincides with the Dirac point and from the sign of the quantum correction to the conductivity. The material can be engineered at will and is clean (good mobility) and there is little bulk contributions to the conductivity inside the band-gap

T-type channel blockade impairs long-term potentiation at the parallel fiber-Purkinje cell synapse and cerebellar learning

CaV3.1 T-type channels are abundant at the cerebellar synapse between parallel fibers and Purkinje cells where they contribute to synaptic depolarization. So far, no specific physiological function has been attributed to these channels neither as charge carriers nor more specifically as Ca 2+ carriers. Here we analyze their incidence on synaptic plasticity, motor behavior, and cerebellar motor learning, comparing WT animals and mice where T-type channel function has been abolished either by gene deletion or by acute pharmacological blockade. At the cellular level, we show that Ca V3.1 channels are required for long-term potentiation at parallel fiber-Purkinje cell synapses. Moreover, basal simple spike discharge of the Purkinje cell in KO mice is modified. Acute or chronic T-type current blockade results in impaired motor performance in particular when a good body balance is required. Because motor behavior integrates reflexes and past memories of learned behavior, this suggests impaired learning. Indeed, subjecting the KO mice to a vestibulo-ocular reflex phase reversal test reveals impaired cerebellum-dependent motor learning. These data identify a role of low-voltage activated calcium channels in synaptic plasticity and establish a role for CaV3.1 channels in cerebellar learning

Staphylococcus aureus RNAIII Binds to Two Distant Regions of coa mRNA to Arrest Translation and Promote mRNA Degradation

Staphylococcus aureus RNAIII is the intracellular effector of the quorum sensing system that temporally controls a large number of virulence factors including exoproteins and cell-wall-associated proteins. Staphylocoagulase is one major virulence factor, which promotes clotting of human plasma. Like the major cell surface protein A, the expression of staphylocoagulase is strongly repressed by the quorum sensing system at the post-exponential growth phase. Here we used a combination of approaches in vivo and in vitro to analyze the mechanism used by RNAIII to regulate the expression of staphylocoagulase. Our data show that RNAIII represses the synthesis of the protein through a direct binding with the mRNA. Structure mapping shows that two distant regions of RNAIII interact with coa mRNA and that the mRNA harbors a conserved signature as found in other RNAIII-target mRNAs. The resulting complex is composed of an imperfect duplex masking the Shine-Dalgarno sequence of coa mRNA and of a loop-loop interaction occurring downstream in the coding region. The imperfect duplex is sufficient to prevent the formation of the ribosomal initiation complex and to repress the expression of a reporter gene in vivo. In addition, the double-strand-specific endoribonuclease III cleaves the two regions of the mRNA bound to RNAIII that may contribute to the degradation of the repressed mRNA. This study validates another direct target of RNAIII that plays a role in virulence. It also illustrates the diversity of RNAIII-mRNA topologies and how these multiple RNAIII-mRNA interactions would mediate virulence regulation

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe