Response to "Comment on Static correlations functions and domain walls in glass-forming liquids: The case of a sandwich geometry" [J. Chem. Phys. 144, 227101 (2016)]

The point-to-set correlation function has proved to be a very valuable tool to probe structural correlations in disordered systems, but more than that, its detailed behavior has been used to try to draw information on the mechanisms leading to glassy behavior in supercooled liquids. For this reason it is of primary importance to discern which of those details are peculiar to glassy systems, and which are general features of confinement. Within the present response we provide an answer to the concerns raised in [J. Chem. Phys. 144, 227101 (2016)]

Response to “Comment on ‘Static correlations functions and domain walls in glass-forming liquids: The case of a sandwich geometry”’ [J. Chem. Phys. 144, 227101 (2016)]

The point-to-set correlation function has proved to be a very valuable tool to probe structural correlations in disordered systems, but more than that, its detailed behavior has been used to try to draw information on the mechanisms leading to glassy behavior in supercooled liquids. For this reason it is of primary importance to discern which of those details are peculiar to glassy systems, and which are general features of confinement. Thus the concerns raised in Ref. 1 definitely need to meet an answer. The Comment proposes an alternative analysis of the numerical data presented in Ref. 2, according to which the behaviour of the point-to-set correlation function can be interpreted as a linear superposition of boundary effects, rather than the effect of non-trivial thermodynamics. We believe this alternative explanation is not compelling.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Interaction d'une vésicule avec des parois solides à faible nombre de Reynolds

Ces dernières années la micro-fluidique a développé des techniques qui permettent d’étudier et manipuler des objets déformables micrométriques (gouttes, vésicules, capsules...). Parmi les applications possibles de ces objets on peut citer l'encapsulation des médicaments pour délivrer des substances dans le sang, le plus souvent à côté des parois des capillaires sanguins, ou alors l'utilisation comme micro-réacteur. Les vésicules sont des gouttes immergées dans un fluide externe visqueux, dont le rayon vaut quelques dizaines de micromètres et entourées par une membrane imperméable constituée de lipides, dont l’épaisseur est approximativement 4 nm. Leur dynamique est gouvernée principalement par les forces de flexion, la préservation de la surface membranaire et du volume interne sur l’échelle de temps des expériences typiques. Ces caractéristiques donnent aux vésicules sous écoulement des comportements bien plus riches que pour le cas des gouttes. Les vésicules représentent ainsi un modèle très général d'objets facilement déformables dans un fluide et en même temps un problème d’interaction fluide-structure à faible nombre de Reynolds. Pour une meilleure compréhension de l'interaction des vésicules avec des structures solides, nous avons étudié le comportement d'une vésicule à proximité de parois rigides en utilisant la méthode des éléments de frontière (BEM), particulièrement adaptée aux écoulements de Stokes. En particulier nous avons focalisé nos études sur la dynamique de l'étalement d'une vésicule sur une paroi perpendiculaire à la gravité et sur le transport dans un capillaire d'une vésicule soumise à un écoulement de Poiseuille

Response to “Comment on ‘Static correlations functions and domain walls in glass-forming liquids: The case of a sandwich geometry”’ [J. Chem. Phys. 144, 227101 (2016)]

The point-to-set correlation function has proved to be a very valuable tool to probe structural correlations in disordered systems, but more than that, its detailed behavior has been used to try to draw information on the mechanisms leading to glassy behavior in supercooled liquids. For this reason it is of primary importance to discern which of those details are peculiar to glassy systems, and which are general features of confinement. Thus the concerns raised in Ref. 1 definitely need to meet an answer. The Comment proposes an alternative analysis of the numerical data presented in Ref. 2, according to which the behaviour of the point-to-set correlation function can be interpreted as a linear superposition of boundary effects, rather than the effect of non-trivial thermodynamics. We believe this alternative explanation is not compelling.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

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

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Vesicle shapes under confined geometry

Les vésicules sont gouttes de rayon de quelques dizaines de micromètres, limitées par une membrane lipidique imperméable d'environ 4 nm d'épaisseur, et immergées dans un fluide visqueux externe. Les propriétés spécifiques de la membrane de la vésicule rendent le système très déformable et très contraint dans le même temps. Les vésicules représentent également un modèle simplifié intéressant pour les globules rouges, car ils partagent aussi certains comportements mécaniques similaires.Ce manuscrit s’intéresse à la modélisation d'une vésicule soumise à des contraintes externes d'origine hydrodynamique, dans le régime Stokes et dans des domaines confinés. À partir d'un modèle BEM déjà existant pour des fluides infinis, des méthodes numériques originales sont développés pour faire face au calcul des interactions entre la membrane de la vésicule et les frontières solides. Une attention particulière est accordée à la situation d'une vésicule qui sédimente vers un mur horizontal et une vésicule soumise à un écoulement de Poiseuille dans un capillaire étroit.Vesicles are drops of radius of a few tens micrometers, bounded by an impermeable lipid membrane of approximately 4 nm thickness, and embedded in an external viscous fluid. The specific properties of the vesicle membrane make the system very deformable and very constrained at the same time. Vesicles represent also an interesting simplified model for red blood cells, since they also share some similar mechanical behaviours.This manuscript deals with the modeling of a vesicle subjected to external stresses of hydrodynamical origin, in the Stokes regime and in confined domains. Starting from an existing BEM model for free space flows, original numerical methods are developed to deal with the computation of interactions between the vesicle membrane and solid boundaries. A particular attention is paid to the situation of a vesicle sedimenting towards a planar wall and a vesicle submitted to a Poiseuille flow in a narrow capillary