Interactive Detailed Cutting of Thin Sheets

International audienceIn this paper we propose a method for the interactive detailed cutting of deformable thin sheets. Our method builds on the ability of frame-based simulation to solve for dynamics using very few control frames while embedding highly detailed geometry - here an adaptive mesh that accurately represents the cut boundaries.Our solution relies on a non-manifold grid to compute shape functions that faithfully adapt to the topological changes occurring while cutting. New frames are dynamically inserted to describe new regions. We provide incremental mechanisms for updating simulation data, enabling us to achieve interactive rates. We illustrate our method with examples inspired by the traditional Kirigami artform

Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes

Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson’s disease (PD) and Alzheimer’s disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues

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

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

Sudden coma onset following simultaneous bilateral carotid occlusion

International audienceNo abstract availabl

Repurposing site-specific recombinases for synthetic biology

Lun Cui, François St-Pierre, and Keith Shearwi

Pression théorique et pression mesurée in situ des bas médicaux de compression : Apport de l'imagerie médicale et des techniques de simulations numériques

National audienceLa compression est une action à caractère mécanique dont l'efficacité thérapeutique est reconnue pour traiter les maladies veineuses et les dérèglements du système lymphatique. Pourtant, son mode d'action est, aujourd'hui encore, peu connu bien que le concept soit simple puisque les pressions de compression résultent de l'équilibre mécanique entre le membre et l'article de compression. La méthodologie adoptée dans cette étude s'appuie sur les outils de simulation numérique répandus dans le domaine de la mécanique, tels que le logiciel Abaqus®. La connaissance du comportement des articles de compression autant que celle de la géométrie de la jambe sont nécessaires à ces simulations. Dans un premier temps, la géométrie réelle des jambes est déterminée en traitant des images issues d'une acquisition par scanner hélicoïdal. Ensuite, le comportement mécanique des bas médicaux de compression (BMC) est caractérisé, puis des simulations numériques sont conduites afin de déterminer la topographie des pressions de compression qui s'exercent sur les sections d'une jambe. Afin de valider l'approche envisagée dans un cadre simplifié (abstraction des propriétés visco-élastiques de la peau), les travaux sont effectués sur une jambe modèle en plastique moulée sur une jambe humaine vivante. Enfin, des mesures de pression in situ avec l'appareil SIGaT sont réalisées sur cette jambe modèle; elles permettent de recouper les pressions simulées mais également de valider le capteur SIGaT utilisé ici. ====================================== Compression is a mechanical action which therapeutical efficiency is recognized for the treatment of venous diseases and lymphatic disorders. However, even if the concept is simple as compression pressures result from the mechanical balance between the limb and the compression garment, the exact mecanism and topography of the compression are not well known. The methodology of this paper is based on digital simulation tools widely used in the field of mechanics, the ABAQUS® software. The knowledge of compression garments' behaviour and of the leg's geometry are necessary for these simulations. A spiral CT-scan is initially used to determine the actual geometry of the legs. The constitutive law of the compression garment is then characterized. Finally, in order to determine the topography of the compression pressures exerted on sections of a leg, digital simulations are carried out . In order to validate the considered approach in a simplified framework (abstraction of the visco-elastic properties of the skin), the work is conducted on a plastic model-leg moulded on a live human leg. Finally, in-situ pressure measurements are conducted on the model-leg with the SIGaT device. They allow to cross-check the simulated pressure values, but also to validate the SIGaT sensor used in this study

A CRISPRi screen in E. coli reveals sequence-specific toxicity of dCas9

CRISPR interference (CRISPRi) is a method for targeted silencing of transcription that requires the coexpression of protein dCas9 and a customized guide RNA. Here, Cui et al. show that certain guide RNAs induce toxicity in E. coli, and provide design rules to minimize off-target effects