Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Evaluation de l'endoscopie à haute définition couplée au système FICE (Fujinon Intelligent Chromo Endoscopy) dans le diagnostic de la métaplasie intestinale dans l'endobrachyoesophage

BREST-BU Médecine-Odontologie (290192102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Effect of the metal promoter on the performances of H-ZSM5 in ethylene aromatization

International audienceThe effect of the metal and the zeolite on the physicochemical properties and catalytic performances in ethylene aromatization was investigated on M/H-ZSM5 (M = Ni, Mo, Zn and Ga). The addition of the metal to the zeolite increases the amount of Lewis acid sites and in parallel decreased the amount of Brønsted ones. The extent of the change depended mainly on the location and dispersion of the metal cation, which varied not only with the nature of the metal but also with the one of the metal precursor. The higher Lewis acidity associated with the lowest Brønsted acidity was obtained with the Zn/H-ZSM5 catalyst. Ethylene aromatization was studied at 500 °C and atmospheric pressure. For the catalyst series, it was demonstrated that the ethylene conversion and yield in aromatic products were proportional to the number of Lewis acid sites, except for Ni/H-ZSM5 that presented a singular behavior with a high initial conversion but rapid deactivation, due to carbon formation. Among the other catalysts, Zn/H-ZSM5 led to the highest ethylene conversion and yield in aromatics. An increase in Zn content increased the amount of Lewis acid sites, decreased the amount of Brønsted acid sites, which favored the initial catalytic performances but also decreased the stability of the Zn/H-ZSM5 catalyst

Ancient genomes from present-day France unveil 7,000 years of its demographic history

International audienceGenomic studies conducted on ancient individuals across Europe have revealed how migrations have contributed to its present genetic landscape, but the territory of present-day France has yet to be connected to the broader European picture. We generated a large dataset comprising the complete mitochondrial genomes, Y chromosome markers and genotypes on a number of nuclear loci of interest of 243 individuals sampled across present-day France over a period spanning 7,000 years, complemented with a partially overlapping dataset of 58 low-coverage genomes. This panel provides a high-resolution transect of the dynamics of maternal and paternal lineages in France as well as of autosomal genotypes. Parental lineages and genomic data both revealed demographic patterns in France for the Neolithic and Bronze Age transitions consistent with neighboring regions, first with a migration wave of Anatolian farmers followed by varying degrees of admixture with autochthonous hunter-gatherers, then substantial gene flow from individuals deriving part of their ancestry from the Pontic Steppe at the onset of the Bronze Age. Our data have also highlighted the persistence of the Magdalenian-associated ancestry in hunter-gatherer populations outside of Spain and thus provide arguments for an expansion of these populations at the end of the Paleolithic period more northerly than what has been described so far. Finally, no major demographic changes were detected during the transition between the Bronze and Iron Ages

Effects of waveform model systematics on the interpretation of GW150914

29 pages, 9 figures, see paper for full list of authorsInternational audienceParameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect sub-dominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's equations, any such calibration is accurate only to some non-zero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameter-space coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analyses on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edge-on to the detector over a small range of choices of polarization angles, and also for eccentricities greater than ∼0.05. For signals with higher signal-to-noise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitational-wave measurements, making more accurate models desirable for future observations