Pre-failure behaviour of an unstable limestone cliff from displacement and seismic data

We monitored the displacement and seismic activity of an unstable vertical rock slice in a natural limestone cliff of the southeast Vercors massif, southeast France, during the months preceding its collapse. Displacement measurements showed an average acceleration of the movement of its top, with clear increases in the displacement velocity and in the discrete seismic event production rate during periods where temperature falls, with more activity when rainfall or frost occurs. Crises of discrete seismic events produce high amplitudes in periodograms, but do not change the high frequency base noise level rate. We infer that these crises express the critical crack growth induced by water weakening (from water vapor condensation or rain) of the rock strength rather than to a rapid change in applied stresses. Seismic noise analysis showed a steady increase in the high frequency base noise level and the emergence of spectral modes in the signal recorded by the sensor installed on the unstable rock slice during the weeks preceding the collapse. High frequency seismic noise base level seems to represent subcritical crack growth. It is a smooth and robust parameter whose variations are related to generalized changes in the rupture process. Drop of the seismic noise amplitude was concomitant with the emergence of spectral modes – that are compatible with high-order eigenmodes of the unstable rock slice – during the later stages of its instability. Seismic noise analysis, especially high frequency base noise level analysis may complement that of inverse displacement velocity in early-warning approaches when strong displacement fluctuations occur

Machine phenotyping of cluster headache and its response to verapamil

Cluster headache is characterized by recurrent, unilateral attacks of excruciating pain associated with ipsilateral cranial autonomic symptoms. Although a wide array of clinical, anatomical, physiological, and genetic data have informed multiple theories about the underlying pathophysiology, the lack of a comprehensive mechanistic understanding has inhibited, on the one hand, the development of new treatments and, on the other, the identification of features predictive of response to established ones. The first-line drug, verapamil, is found to be effective in only half of all patients, and after several weeks of dose escalation, rendering therapeutic selection both uncertain and slow. Here we use high-dimensional modelling of routinely acquired phenotypic and MRI data to quantify the predictability of verapamil responsiveness and to illuminate its neural dependants, across a cohort of 708 patients evaluated for cluster headache at the National Hospital for Neurology and Neurosurgery between 2007 and 2017. We derive a succinct latent representation of cluster headache from non-linear dimensionality reduction of structured clinical features, revealing novel phenotypic clusters. In a subset of patients, we show that individually predictive models based on gradient boosting machines can predict verapamil responsiveness from clinical (410 patients) and imaging (194 patients) features. Models combining clinical and imaging data establish the first benchmark for predicting verapamil responsiveness, with an area under the receiver operating characteristic curve of 0.689 on cross-validation (95% confidence interval: 0.651 to 0.710) and 0.621 on held-out data. In the imaged patients, voxel-based morphometry revealed a grey matter cluster in lobule VI of the cerebellum (–4, –66, –20) exhibiting enhanced grey matter concentrations in verapamil non-responders compared with responders (familywise error-corrected P = 0.008, 29 voxels). We propose a mechanism for the therapeutic effect of verapamil that draws on the neuroanatomy and neurochemistry of the identified region. Our results reveal previously unrecognized high-dimensional structure within the phenotypic landscape of cluster headache that enables prediction of treatment response with modest fidelity. An analogous approach applied to larger, globally representative datasets could facilitate data-driven redefinition of diagnostic criteria and stronger, more generalizable predictive models of treatment responsiveness

Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution

The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. We used classical dense photometric lightcurves from several sources and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetics and observed pole-latitude distributions, we were able to constrain the typical values of the cYORP parameter as between 0.05 and 0.6.Comment: Accepted for publication in A&A, January 15, 201

Bioactivity, biocompatibility and antimicrobial properties of a chitosan-mineral composite for periodontal tissue regeneration

A composite membrane of the polymer, chitosan, and the silver-exchanged mineral phase, tobermorite, was prepared by solvent casting and characterised by scanning electron microscopy and Fourier transform infrared spectroscopy. The in vitro bioactivity, cytocompatibility and antimicrobial activity of the composite were evaluated with respect to its potential application as a guided tissue regeneration (GTR) membrane. The in vitro bioactivity was verified by the formation of hydroxyapatite on the surface of the membrane in simulated body fluid and its cytocompatibility was established using MG63 human osteosarcoma cells. The presence of silver ions conferred significant antimicrobial activity against S. aureus, P. aeruginosa and E. coli. The findings of this investigation have indicated that the chitosansilver-tobermorite composite is a prospective candidate for GTR applications

Genome-Wide Association Study Identifies Risk Loci for Cluster Headache

OBJECTIVE: To identify susceptibility loci for cluster headache and obtain insights into relevant disease pathways. METHODS: We carried out a genome-wide association study, where 852 UK and 591 Swedish cluster headache cases were compared with 5,614 and 1,134 controls, respectively. Following quality control and imputation, single variant association testing was conducted using a logistic mixed model, for each cohort. The two cohorts were subsequently combined in a merged analysis. Downstream analyses, such as gene-set enrichment, functional variant annotation, prediction and pathway analyses, were performed. RESULTS: Initial independent analysis identified two replicable cluster headache susceptibility loci on chromosome 2. A merged analysis identified an additional locus on chromosome 1 and confirmed a locus significant in the UK analysis on chromosome 6, which overlaps with a previously known migraine locus. The lead single nucleotide polymorphisms were rs113658130 (p = 1.92 x 10-17 , OR [95%CI] = 1.51 [1.37-1.66]) and rs4519530 (p = 6.98 x 10-17 , OR = 1.47 [1.34-1.61]) on chromosome 2, rs12121134 on chromosome 1 (p = 1.66 x 10-8 , OR = 1.36 [1.22-1.52]) and rs11153082 (p = 1.85 x 10-8 , OR = 1.30 [1.19-1.42]) on chromosome 6. Downstream analyses implicated immunological processes in the pathogenesis of cluster headache. INTERPRETATION: We identified and replicated several genome-wide-significant associations supporting a genetic predisposition in cluster headache in a genome-wide association study involving 1,443 cases. Replication in larger independent cohorts combined with comprehensive phenotyping, in relation to e.g. treatment response and cluster headache subtypes, could provide unprecedented insights into genotype-phenotype correlations and the pathophysiological pathways underlying cluster headache

Genome-Wide Association Study Identifies Risk Loci for Cluster Headache.

OBJECTIVE: This study was undertaken to identify susceptibility loci for cluster headache and obtain insights into relevant disease pathways. METHODS: We carried out a genome-wide association study, where 852 UK and 591 Swedish cluster headache cases were compared with 5,614 and 1,134 controls, respectively. Following quality control and imputation, single variant association testing was conducted using a logistic mixed model for each cohort. The 2 cohorts were subsequently combined in a merged analysis. Downstream analyses, such as gene-set enrichment, functional variant annotation, prediction and pathway analyses, were performed. RESULTS: Initial independent analysis identified 2 replicable cluster headache susceptibility loci on chromosome 2. A merged analysis identified an additional locus on chromosome 1 and confirmed a locus significant in the UK analysis on chromosome 6, which overlaps with a previously known migraine locus. The lead single nucleotide polymorphisms were rs113658130 (p = 1.92 × 10-17 , odds ratio [OR] = 1.51, 95% confidence interval [CI] = 1.37-1.66) and rs4519530 (p = 6.98 × 10-17 , OR = 1.47, 95% CI = 1.34-1.61) on chromosome 2, rs12121134 on chromosome 1 (p = 1.66 × 10-8 , OR = 1.36, 95% CI = 1.22-1.52), and rs11153082 (p = 1.85 × 10-8 , OR = 1.30, 95% CI = 1.19-1.42) on chromosome 6. Downstream analyses implicated immunological processes in the pathogenesis of cluster headache. INTERPRETATION: We identified and replicated several genome-wide significant associations supporting a genetic predisposition in cluster headache in a genome-wide association study involving 1,443 cases. Replication in larger independent cohorts combined with comprehensive phenotyping, in relation to, for example, treatment response and cluster headache subtypes, could provide unprecedented insights into genotype-phenotype correlations and the pathophysiological pathways underlying cluster headache. ANN NEUROL 2021

Development of different analytical techniques to investigate radionuclides difficult to measure and to improve detection limits.

International audienceThe radioactive waste management is a challenging task faced by nuclear powercountries and is a prime concern for the public and therefore for control authorities. In France,several nuclear facilities were shut down few years ago and are now under dismantling. In thesefacilities, after the disposal of different equipments (glove boxes etc.) and a cleaning-up step,laboratories are subject to decommissioning and sometimes demolition. In order to establish theworking procedure of dismantling, an inventory on the radioactive level of the various materialsand areas is essential. Furthermore, correct waste classification is crucial to define the appropriatefinal disposal repository and also to keep disposal cost down to a minimum. For all thesecharacterizations, the laboratory in CEA Saclay (LASE) develops radiochemical procedures andanalytical techniques to provide results with high confidence level and with very low detectionlimits

Exploring Arctic Transpolar Drift during dramatic sea ice retreat

The Arctic is undergoing significant environmental changes due to climate warming. The most evident signal of this warming is the shrinking and thinning of the ice cover of the Arctic Ocean. If the warming continues, as global climate models predict, the Arctic Ocean will change from a perennially ice-covered to a seasonally ice-free ocean. Estimates as to when this will occur vary from the 2030s to the end of this century. One reason for this huge uncertainty is the lack of systematic observations describing the state, variability, and changes in the Arctic Ocean

GROWTH POLE RING protein forms a 200-nm-diameter ring structure essential for polar growth and rod shape in Agrobacterium tumefaciens

Polar growth in Agrobacterium pirates and repurposes well-known bacterial cell cycle proteins, such as FtsZ, FtsA, PopZ, and PodJ. Here we identify a heretofore unknown protein that we name GROWTH POLE RING (GPR) due to its striking localization as a hexameric ring at the growth pole during polar growth. GPR also localizes at the midcell late in the cell cycle just before division, where it is then poised to be precisely localized at new growth poles in sibling cells. GPR is 2,115 aa long, with two N-terminal transmembrane domains placing the bulk of the protein in the cytoplasm, N- and C-terminal proline-rich disordered regions, and a large 1,700-aa central region of continuous α-helical domains. This latter region contains 12 predicted adjacent or overlapping apolipoprotein domains that may function to sequester lipids during polar growth. Stable genetic deletion or riboswitch-controlled depletion results in spherical cells that grow poorly; thus, GPR is essential for wild-type growth and morphology. As GPR has no predicted enzymatic domains and it forms a distinct 200-nm-diameter ring, we propose that GPR is a structural component of an organizing center for peptidoglycan and membrane syntheses critical for cell envelope formation during polar growth. GPR homologs are found in numerous Rhizobiales; thus, our results and proposed model are fundamental to understanding polar growth strategy in a variety of bacterial species

Developpement de nouvelles methodes en vue de la quantification de radionucleides difficilement mesurables dans des dechets nucleaires et amelioration des limites de detection

National audienceAu sein du CEA Saclay, le Laboratoire d'Analyse en Soutien aux Exploitants (LASE) situe au batiment 459 est specialise dans l'analyse de Radionucleides difficilement mesurables dans les dechets nucleaires de faible et moyenne activite. Une vingtaine de modes operatoires existent au laboratoire pour analyser les differents Radionucleides, tels que le 3H, le 14C, le 36Cl, le 63Ni, le 108mAg ou l'129I. En constante evolution, ces protocoles peuvent etre appliques a de nombreux types de materiaux (solides, liquides, boues) et l'utilisation de traceurs permet de suivre les mises en solution et les multiples etapes des separations radiochimiques indispensables pour la mesure de ces emetteurs. Apres une breve presentation generale de la methodologie d'analyse des Radionucleides difficilement mesurables, quelques exemples seront presentes.En tant qu'emetteurs beta, le 3H et le 14C sont mesures au laboratoire par scintillation liquide apres une etape de combustion permettant d'eliminer les interferents. Le LASE s'est recemment dote de deux fours a pyrolyse multi-tubes afin d'accroitre sa capacite d'analyses du 3H et du 14C face a l'accroissement des demandes liees aux demantelements des installations nucleaires. Ce nouveau protocole est en cours de validation a partir de la preparation de betons dopes en 3H et 14C et d'une comparaison avec un laboratoire partenaire.En tant qu'emetteur beta, le 36Cl est analyse au laboratoire par scintillation liquide apres un protocole radiochimique base sur la synthese organique d'une molecule marquee au 36Cl. En raison de la limite maximale d'acceptabilite peu elevee (5 Bq/g) au centre de l'Aube pour le 36Cl, le LASE s'est oriente vers la spectrometrie de masse par accelerateur (SMA) comme technique alternative de detection. La SMA a ete recemment appliquee avec succes a l'analyse d'echantillons d'aciers actives permettant de quantifier des teneurs en 36Cl de l'ordre de 10-3 Bq/g. L'129I contenu dans des bitumes a aussi ete analyse par SMA.En raison de l'evolution des reglementations dans le domaine des risques chimiques et notamment de la directive REACH, des composes, tels que le chloroforme, doivent etre progressivement elimines des modes operatoires. La methode de reference du 63Ni est basee sur une extraction liquide-liquide avec du chloroforme. Le LASE a ainsi developpe un protocole alternatif reposant sur une purification du 63Ni par resine d'extraction chromatographique dite resine Ni. Ce mode operatoire permet d'atteindre une selectivite et une efficacite equivalentes a celles du mode operatoire de reference.Recemment, le LASE a egalement mis au point une methode d'analyse du 126Sn dans les dechets nucleaires. Apres purification, le 126Sn peut etre detecte par ICP-MS Q a des teneurs de l'ordre de 10-1 Bq/g. Afin de verifier l'homogeneite des echantillons et d'eviter leurs mises en solution fastidieuses, le LASE developpe aussi des mesures par spectrometrie gamma sur solides. Cette technique permet d'atteindre une meilleure representativite et de diminuer les limites de detection d'un facteur 1 a 100