85,762 results on '"Tremblay, A."'
Search Results
2. Ambipolar doping of a charge-transfer insulator in the Emery model
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Sordi, G., Reaney, G. L., Kowalski, N., Sémon, P., and Tremblay, A. -M. S.
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Superconductivity - Abstract
Understanding the similarities and differences between adding or removing electrons from a charge-transfer insulator may provide insights about the origin of the electron-hole asymmetry found in cuprates. Here we study with cellular dynamical mean-field theory the Emery model set in the charge-transfer insulator regime, and dope it with either electrons or holes. We consider the normal state only and focus on the doping evolution of the orbital character of the dopants and on the nature of the doping driven transition. Regarding the orbital character of the dopants, we found an electron-hole asymmetry: doped electrons mostly enter the copper orbitals, whereas doped holes mostly enter the oxygen orbitals. Regarding the nature of the doping driven transition, we found no qualitative electron-hole asymmetry: upon either electron or hole doping, there is a two-stage transition from a charge-transfer insulator to a strongly correlated pseudogap and then to a metal. This shows that a strongly correlated pseudogap is an emergent feature of doped correlated insulators in two dimensions, in qualitative agreement with recent experiments on ambipolar Sr$_{1-x}$La$_{x}$CuO$_{2+y}$ cuprate films. Our results indicate that merely doping with holes or electrons a charge-transfer insulator is not sufficient for explaining the electron-hole asymmetry observed in the normal state phase diagram of cuprates. Our work reinforces the view that actual hole-doped cuprates are more correlated than their electron-doped counterparts., Comment: 21 pages, 14 figures
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- 2024
3. Antiferromagnetic pseudogap in the two-dimensional Hubbard model deep in the renormalized classical regime
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Vilk, Y. M., Lahaie, Camille, and Tremblay, A. -M. S.
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Condensed Matter - Strongly Correlated Electrons - Abstract
Long-wavelength spin fluctuations prohibit antiferromagnetic long-range order at finite temperature in two dimensions. Nevertheless, the correlation length starts to grow rapidly at a crossover temperature, leading to critical slowing down and to a renormalized-classical regime over a wide range of temperature, between a fraction of the mean-field transition temperature and the zero-temperature ordered state. This leads to a single-particle pseudogap of the kind observed in electron-doped cuprates. Very few theoretical methods can claim an accurate description of this regime. The challenge is that in this regime Fermi-liquid quasiparticles are already destroyed and new quasiparticles of the ordered state are not fully formed yet. Here, we study this problem for the two-dimensional Hubbard model by first generalizing the two-particle self-consistent approach. Using a special algorithm, spin fluctuations are treated in the thermodynamic limit even for large correlation lengths. The effects of Kanamori-Br\"uckner screening, of classical and of quantum fluctuations are taken into account. Results are presented at half-filling for the one-band Hubbard model with nearest-neighbor hopping. They agree well with available benchmark diagrammatic quantum Monte Carlo at high temperature where the pseudogap opens up. In addition to temperature-dependent spectral properties, we find quantum corrections to the zero-temperature renormalized mean-field antiferromagnetic gap. Finally, analytic continuation of the Matsubara results for spectral functions show that the pseudogap opens up at significantly higher temperature than was previously identified based on the Matsubara data only.
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- 2024
4. Unraveling the role of merger histories in the population of Insitu stars: linking IllustrisTNG cosmological simulation to H3 survey
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Emami, Razieh, Hernquist, Lars, Smith, Randall, Steiner, James F., Tremblay, Grant, Finkbeiner, Douglas, Vogelsberger, Mark, Grindlay, Josh, Marinacci, Federico, Su, Kung-Yi, Garraffo, Cecilia, Ting, Yuan-Sen, Cargile, Phillip A., Davies, Rebecca L., Benton, Chloë E., Li, Yijia, Bugiani, Letizia, Khoram, Amir H., and Bose, Sownak
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - Solar and Stellar Astrophysics ,High Energy Physics - Phenomenology - Abstract
We undertake a comprehensive investigation into the distribution of insitu stars within Milky Way-like galaxies, leveraging TNG50 simulations and comparing their predictions with data from the H3 survey. Our analysis reveals that 28% of galaxies demonstrate reasonable agreement with H3, while only 12% exhibit excellent alignment in their profiles, regardless of the specific spatial cut employed to define insitu stars. To uncover the underlying factors contributing to deviations between TNG50 and H3 distributions, we scrutinize correlation coefficients among internal drivers(e.g., virial radius, star formation rate [SFR]) and merger-related parameters (such as the effective mass-ratio, mean distance, average redshift, total number of mergers, average spin-ratio and maximum spin alignment between merging galaxies). Notably, we identify significant correlations between deviations from observational data and key parameters such as the median slope of virial radius, mean SFR values, and the rate of SFR change across different redshift scans. Furthermore, positive correlations emerge between deviations from observational data and parameters related to galaxy mergers. We validate these correlations using the Random Forest Regression method. Our findings underscore the invaluable insights provided by the H3 survey in unraveling the cosmic history of galaxies akin to the Milky Way, thereby advancing our understanding of galactic evolution and shedding light on the formation and evolution of Milky Way-like galaxies in cosmological simulations., Comment: 20 pages, 13 figures
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- 2024
5. A quantum mechanical evaluation of the intermediate scattering function
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Bindech, Oussama, Marquardt, Roberto, Gatti, Fabien, Mandal, Souvik, and Tremblay, Jean Christophe
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Quantum Physics ,81, 82 - Abstract
The intermediate scattering function is interpreted as a correlation function of thermal wave packets of the scattering centers perturbed by the scattering particles at different times. A proof of concept is given at the example of ballistic moving centers. The ensuing numerical method is then illustrated at the example of CO adsorbed on Cu(100)., Comment: 8 pages, 2 figures
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- 2024
6. The DBL Survey I: discovery of 34 double-lined double white dwarf binaries
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Munday, James, Pelisoli, Ingrid, Tremblay, P. E., Marsh, T. R., Nelemans, Gijs, Bédard, Antoine, Toonen, Silvia, Breedt, Elmé, Cunningham, Tim, O'Brien, Mairi W., and Dawson, Harry
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Astrophysics - Solar and Stellar Astrophysics - Abstract
We present the first discoveries of the double-lined double white dwarf (DBL) survey that targets over-luminous sources with respect to the canonical white dwarf cooling sequence according to a set of well-defined criteria. The primary goal of the DBL survey is to identify compact double white dwarf binary star systems from a unique spectral detection of both stars, which then enables a precise quantification of the atmospheric parameters and radial velocity variability of a system. Our search of 117 candidates that were randomly selected from a magnitude limited sample of 399 yielded a 29% detection efficiency with 34 systems exhibiting a double-lined signature. A further 38 systems show strong evidence of being single-lined or potentially-double-lined double white dwarf binaries and 7 single-lined sources from the full observed sample are radial velocity variable. The 45 remaining candidates appear as a single WD with no companion or a non-DA white dwarf, bringing the efficiency of detecting binaries to 62%. Atmospheric fitting of all double-lined systems reveals a large fraction that have two similar mass components that combine to a total mass of 1.0-1.3 solar masses - a class of double white dwarf binaries that may undergo a sub-Chandrasekhar mass type Ia detonation or merge to form a massive O/Ne WD, although orbital periods are required to infer on which timescales. One double-lined system located 49pc away, WDJ181058.67+311940.94, is super-Chandrasekhar mass, making it the second such double white dwarf binary to be discovered., Comment: Accepted for publication in MNRAS. 17 pages (plus 5 pages in the appendix). 12 figures
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- 2024
7. White dwarf constraints on geological processes at the population level
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Buchan, Andrew M., Bonsor, Amy, Rogers, Laura K., Brouwers, Marc G., Shorttle, Oliver, and Tremblay, Pier-Emmanuel
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Solar and Stellar Astrophysics - Abstract
White dwarf atmospheres are frequently polluted by material from their own planetary systems. Absorption features from Ca, Mg, Fe and other elements can provide unique insights into the provenance of this exoplanetary material, with their relative abundances being used to infer accretion of material with core- or mantle-like composition. Across the population of white dwarfs, the distribution of compositions reveals the prevalence of geological and collisional processing across exoplanetary systems. By predicting the distribution of compositions in three evolutionary scenarios, this work assesses whether they can explain current observations. We consider evolution in an asteroid belt analog, in which collisions between planetary bodies that formed an iron core lead to core- or mantle-rich fragments. We also consider layer-by-layer accretion of individual bodies, such that the apparent composition of atmospheric pollution changes during the accretion of a single body. Finally, we consider that compositional spread is due to random noise. We find that the distribution of Ca, Fe and Mg in a sample of 202 cool DZs is consistent with the random noise scenario, although 7 individual systems show strong evidence of core-mantle differentiation from additional elements and/or low noise levels. Future surveys which detect multiple elements in each of a few hundred white dwarfs, with well understood biases, have the potential to confidently distinguish between the three models., Comment: 20 pages, 13 figures. Accepted for publication in MNRAS
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- 2024
- Full Text
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8. J-PLUS: The fraction of calcium white dwarfs along the cooling sequence
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López-Sanjuan, C., Tremblay, P. -E., O'Brien, M. W., Spinoso, D., Ederoclite, A., Ramió, H. Vázquez, Cenarro, A. J., Marín-Franch, A., Civera, T., Carrasco, J. M., Gänsicke, B. T., Fusillo, N. P. Gentile, Hernán-Caballero, A., Hollands, M. A., del Pino, A., Sánchez, H. Domínguez, Fernández-Ontiveros, J. A., Jiménez-Esteban, F. M., Rebassa-Mansergas, A., Schmidtobreick, L., Angulo, R. E., Cristòbal-Hornillos, D., Dupke, R. A., Hernández-Monteagudo, C., Moles, M., Sodré Jr., L., and Varela, J.
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
We used the Javalambre Photometric Local Universe Survey (J-PLUS) DR2 photometry in twelve optical bands over 2176 deg2 to estimate the fraction of white dwarfs with presence of CaII H+K absorption along the cooling sequence. We compared the J-PLUS photometry against metal-free theoretical models to estimate the equivalent width in the J0395 passband of 10 nm centered at 395 nm (EW_J0395), a proxy to detect calcium absorption. A total of 4399 white dwarfs within 30000 > Teff > 5500 K and mass M > 0.45 Msun were analyzed. Their EW_J0395 distribution was modeled using two populations, corresponding to polluted and non-polluted systems, to estimate the fraction of calcium white dwarfs (f_Ca) as a function of Teff. The probability for each individual white dwarf of presenting calcium absorption, pca, was also computed. The comparison with both the measured Ca/He abundance and the metal pollution from spectroscopy shows that EW_J0395 correlates with the presence of calcium. The fraction of calcium white dwarfs increases from f_Ca = 0 at Teff = 13500 K to f_Ca = 0.15 at Teff = 5500 K. We compare our results with the fractions derived from the 40 pc spectroscopic sample and from SDSS spectra. The trend found in J-PLUS observations is also present in the 40 pc sample, however SDSS shows a deficit of metal-polluted objects at Teff < 12000 K. Finally, we found 39 white dwarfs with pca > 0.99. Twenty of them have spectra presented in previous studies, whereas we observed six additional targets. These 26 objects were all confirmed as metal-polluted systems. The J-PLUS optical data provide a robust statistical measurement for the presence of CaII H+K absorption in white dwarfs. We find a 15 +- 3 % increase in the fraction of calcium white dwarfs from Teff = 13500 K to 5500 K, which reflects their selection function in the optical from the total population of metal-polluted systems., Comment: Submitted to Astronomy and Astrophysics. Comments are welcome
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- 2024
9. NeRFDeformer: NeRF Transformation from a Single View via 3D Scene Flows
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Tang, Zhenggang, Ren, Zhongzheng, Zhao, Xiaoming, Wen, Bowen, Tremblay, Jonathan, Birchfield, Stan, and Schwing, Alexander
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Artificial Intelligence - Abstract
We present a method for automatically modifying a NeRF representation based on a single observation of a non-rigid transformed version of the original scene. Our method defines the transformation as a 3D flow, specifically as a weighted linear blending of rigid transformations of 3D anchor points that are defined on the surface of the scene. In order to identify anchor points, we introduce a novel correspondence algorithm that first matches RGB-based pairs, then leverages multi-view information and 3D reprojection to robustly filter false positives in two steps. We also introduce a new dataset for exploring the problem of modifying a NeRF scene through a single observation. Our dataset ( https://github.com/nerfdeformer/nerfdeformer ) contains 113 synthetic scenes leveraging 47 3D assets. We show that our proposed method outperforms NeRF editing methods as well as diffusion-based methods, and we also explore different methods for filtering correspondences., Comment: 8 pages of main paper, CVPR 2024. Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition. 2024
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- 2024
10. Finding Maximum Common Contractions Between Phylogenetic Networks
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Marchand, Bertrand, Tahiri, Nadia, Tremblay-Savard, Olivier, and Lafond, Manuel
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Computer Science - Data Structures and Algorithms ,Computer Science - Computational Complexity - Abstract
In this paper, we lay the groundwork on the comparison of phylogenetic networks based on edge contractions and expansions as edit operations, as originally proposed by Robinson and Foulds to compare trees. We prove that these operations connect the space of all phylogenetic networks on the same set of leaves, even if we forbid contractions that create cycles. This allows to define an operational distance on this space, as the minimum number of contractions and expansions required to transform one network into another. We highlight the difference between this distance and the computation of the maximum common contraction between two networks. Given its ability to outline a common structure between them, which can provide valuable biological insights, we study the algorithmic aspects of the latter. We first prove that computing a maximum common contraction between two networks is NP-hard, even when the maximum degree, the size of the common contraction, or the number of leaves is bounded. We also provide lower bounds to the problem based on the Exponential-Time Hypothesis. Nonetheless, we do provide a polynomial-time algorithm for weakly-galled networks, a generalization of galled trees., Comment: full version (with complete set of proofs) of WABI 2024 submission
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- 2024
11. Multicomplex Ideals, Modules and Hilbert Spaces
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Courchesne, Derek and Tremblay, Sébastien
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Mathematical Physics ,Mathematics - Rings and Algebras - Abstract
In this article we study some algebraic aspects of multicomplex numbers $\mathbb M_n$. For $n\geq 2$ a canonical representation is defined in terms of the multiplication of $n-1$ idempotent elements. This representation facilitates computations in this algebra and makes it possible to introduce a generalized conjugacy $\Lambda_n$, i.e. a composition of the $n$ multicomplex conjugates $\Lambda_n:=\dagger_1\cdots \dagger_n$, as well as a multicomplex norm. The multicomplex algebra equipped with this norm and $\Lambda_n$ as the involution forms a C$^*$-algebra. The ideals of the ring of multicomplex numbers are then studied in details. Free $\mathbb M_n$-modules and their linear operators are considered. Finally, we develop Hilbert spaces on the multicomplex algebra., Comment: 27 pages
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- 2024
12. A Test of Spectroscopic Age Estimates of White Dwarfs using Wide WD+WD Binaries
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Heintz, Tyler M., Hermes, J. J., Tremblay, P. -E., Rouis, Lou Baya Ould, Redding, Joshua S., Kaiser, B. C., and van Saders, Jennifer L.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
White dwarf stars have been used for decades as precise and accurate age indicators. This work presents a test of the reliability of white dwarf total ages when spectroscopic observations are available. We conduct follow-up spectroscopy of 148 individual white dwarfs in widely separated double-white-dwarf (WD+WD) binaries. We supplement the sample with 264 previously published white dwarf spectra, as well as 1292 high-confidence white dwarf spectral types inferred from their Gaia XP spectra. We find that spectroscopic fits to optical spectra do not provide noticeable improvement to the age agreement among white dwarfs in wide WD+WD binaries. The median age agreement is $\approx$$1.5\sigma$ for both photometrically and spectroscopically determined total ages, for pairs of white dwarfs with each having a total age uncertaintiy $<$ 20\%. For DA white dwarfs, we further find that photometrically determined atmospheric parameters from spectral energy distribution fitting give better total age agreement ($1.0\sigma$, 0.2 Gyr, or 14\% of the binary's average total age) compared to spectroscopically determined parameters from Balmer-line fits (agreement of $1.5\sigma$, 0.3 Gyr, or 28\% of binary's average total age). We find further evidence of a significant merger fraction among wide WD+WD binaries: across multiple spectroscopically identified samples, roughly 20\% are inconsistent with a monotonically increasing initial-final mass relation. We recommend the acquisition of an identification spectrum to ensure the correct atmospheric models are used in photometric fits in order to determine the most accurate total age of a white dwarf star., Comment: 38 pages, 17 figures, submitted to ApJ
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- 2024
13. A broad linewidth, compact, millimeter-bright molecular emission line source near the Galactic Center
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Ginsburg, Adam, Bally, John, Barnes, Ashley T., Battersby, Cara, Budaiev, Nazar, Butterfield, Natalie O., Caselli, Paola, Colzi, Laura, Dutkowska, Katarzyna M., García, Pablo, Gramze, Savannah, Henshaw, Jonathan D., Hu, Yue, Jeff, Desmond, Jiménez-Serra, Izaskun, Kauffmann, Jens, Klessen, Ralf S., Levesque, Emily M., Longmore, Steven N., Lu, Xing, Mills, Elisabeth A. C., Morris, Mark R., Nogueras-Lara, Francisco, Oka, Tomoharu, Pineda, Jaime E., Pillai, Thushara G. S., Rivilla, Víctor M., Sánchez-Monge, Álvaro, Santa-Maria, Miriam G., Smith, Howard A., Sofue, Yoshiaki, Sormani, Mattia C., Tremblay, Grant R., Vermariën, Gijs, Vikhlinin, Alexey, Viti, Serena, Walker, Dan, Wang, Q. Daniel, Xu, Fengwei, and Zhang, Qizhou
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Astrophysics - Astrophysics of Galaxies - Abstract
A compact source, G0.02467-0.0727, was detected in ALMA \threemm observations in continuum and very broad line emission. The continuum emission has a spectral index $\alpha\approx3.3$, suggesting that the emission is from dust. The line emission is detected in several transitions of CS, SO, and SO$_2$ and exhibits a line width FWHM $\approx160$ \kms. The line profile appears Gaussian. The emission is weakly spatially resolved, coming from an area on the sky $\lesssim1"$ in diameter ($\lesssim10^4$ AU at the distance of the Galactic Center; GC). The centroid velocity is $v_{LSR}\approx40$-$50$ \kms, which is consistent with a location in the Galactic Center. With multiple SO lines detected, and assuming local thermodynamic equilibrium (LTE) conditions, $T_\mathrm{LTE} = 13$ K, which is colder than seen in typical GC clouds, though we cannot rule out low-density, subthermally excited, warmer gas. Despite the high velocity dispersion, no emission is observed from SiO, suggesting that there are no strong ($\gtrsim10~\mathrm{km~s}^{-1}$) shocks in the molecular gas. There are no detections at other wavelengths, including X-ray, infrared, and radio. We consider several explanations for the Millimeter Ultra-Broad Line Object (MUBLO), including protostellar outflow, explosive outflow, collapsing cloud, evolved star, stellar merger, high-velocity compact cloud, intermediate mass black hole, and background galaxy. Most of these conceptual models are either inconsistent with the data or do not fully explain it. The MUBLO is, at present, an observationally unique object., Comment: Accepted to ApJL
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- 2024
14. Neural Implicit Representation for Building Digital Twins of Unknown Articulated Objects
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Weng, Yijia, Wen, Bowen, Tremblay, Jonathan, Blukis, Valts, Fox, Dieter, Guibas, Leonidas, and Birchfield, Stan
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Artificial Intelligence ,Computer Science - Graphics ,Computer Science - Robotics - Abstract
We address the problem of building digital twins of unknown articulated objects from two RGBD scans of the object at different articulation states. We decompose the problem into two stages, each addressing distinct aspects. Our method first reconstructs object-level shape at each state, then recovers the underlying articulation model including part segmentation and joint articulations that associate the two states. By explicitly modeling point-level correspondences and exploiting cues from images, 3D reconstructions, and kinematics, our method yields more accurate and stable results compared to prior work. It also handles more than one movable part and does not rely on any object shape or structure priors. Project page: https://github.com/NVlabs/DigitalTwinArt, Comment: CVPR 2024
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- 2024
15. Snap-it, Tap-it, Splat-it: Tactile-Informed 3D Gaussian Splatting for Reconstructing Challenging Surfaces
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Comi, Mauro, Tonioni, Alessio, Yang, Max, Tremblay, Jonathan, Blukis, Valts, Lin, Yijiong, Lepora, Nathan F., and Aitchison, Laurence
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Robotics - Abstract
Touch and vision go hand in hand, mutually enhancing our ability to understand the world. From a research perspective, the problem of mixing touch and vision is underexplored and presents interesting challenges. To this end, we propose Tactile-Informed 3DGS, a novel approach that incorporates touch data (local depth maps) with multi-view vision data to achieve surface reconstruction and novel view synthesis. Our method optimises 3D Gaussian primitives to accurately model the object's geometry at points of contact. By creating a framework that decreases the transmittance at touch locations, we achieve a refined surface reconstruction, ensuring a uniformly smooth depth map. Touch is particularly useful when considering non-Lambertian objects (e.g. shiny or reflective surfaces) since contemporary methods tend to fail to reconstruct with fidelity specular highlights. By combining vision and tactile sensing, we achieve more accurate geometry reconstructions with fewer images than prior methods. We conduct evaluation on objects with glossy and reflective surfaces and demonstrate the effectiveness of our approach, offering significant improvements in reconstruction quality., Comment: 17 pages
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- 2024
16. Random Multi-Type Spanning Forests for Synchronization on Sparse Graphs
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Jaquard, Hugo, Amblard, Pierre-Olivier, Barthelmé, Simon, and Tremblay, Nicolas
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Mathematics - Probability ,Computer Science - Data Structures and Algorithms ,Mathematics - Statistics Theory - Abstract
Random diffusions are a popular tool in Monte-Carlo estimations, with well established algorithms such as Walk-on-Spheres (WoS) going back several decades. In this work, we introduce diffusion estimators for the problems of angular synchronization and smoothing on graphs, in the presence of a rotation associated to each edge. Unlike classical WoS algorithms, these estimators allow for global estimations by propagating along the branches of multi-type spanning forests, and we show that they can outperform standard numerical-linear-algebra solvers in challenging instances, depending on the topology and density of the graph.
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- 2024
17. A candidate supermassive black hole in a gravitationally-lensed galaxy at $z\approx10$
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Kovacs, Orsolya E., Bogdan, Akos, Natarajan, Priyamvada, Werner, Norbert, Azadi, Mojegan, Volonteri, Marta, Tremblay, Grant R., Chadayammuri, Urmila, Forman, William R., Jones, Christine, and Kraft, Ralph P.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
While supermassive black holes (BHs) are widely observed in the nearby and distant universe, their origin remains debated with two viable formation scenarios with light and heavy seeds. In the light seeding model, the first BHs form from the collapse of massive stars with masses of $10-100 \ \rm{M_{\odot}}$, while the heavy seeding model posits the formation of $10^{4-5} \ \rm{M_{\odot}}$ seeds from direct collapse. The detection of BHs at redshifts $z\gtrsim10$, edging closer to their formation epoch, provides critical observational discrimination between these scenarios. Here, we focus on the JWST-detected galaxy, GHZ 9, at $z\approx10$ that is lensed by the foreground cluster, Abell 2744. Based on 2.1 Ms deep Chandra observations, we detect a candidate X-ray AGN, which is spatially coincident with the high-redshift galaxy, GHZ 9. The BH candidate is inferred to have a bolometric luminosity of $(1.0^{+0.5}_{-0.4})\times10^{46} \ \rm{erg \ s^{-1}}$, which corresponds to a BH mass of $(8.0^{+3.7}_{-3.2})\times10^7 \ \rm{M_{\odot}}$ assuming Eddington-limited accretion. This extreme mass at such an early cosmic epoch suggests the heavy seed origin for this BH candidate. Based on the Chandra and JWST discoveries of extremely high-redshift quasars, we have constructed the first simple AGN luminosity function extending to $z\approx10$. Comparison of this luminosity function with theoretical models indicates an over-abundant $z\approx10$ BH population, consistent with a higher-than-expected seed formation efficiency., Comment: 9 pages, 4 figures, accepted for publication in The Astrophysical Journal Letters
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- 2024
18. Two distinct molecular cloud populations detected in massive galaxies
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Rose, Tom, McNamara, B. R., Combes, F., Edge, A. C., McDonald, M., O'Sullivan, Ewan, Russell, H., Fabian, A. C., Ferland, G., Salome, P., and Tremblay, G.
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Astrophysics - Astrophysics of Galaxies - Abstract
We present new ALMA observations of CO, CN, CS, HCN and HCO$^{+}$ absorption seen against the bright and compact radio continuum sources of eight massive galaxies. Combined with archival observations, they reveal two distinct populations of molecular clouds, which we identify by combining CO emission and absorption profiles to unambiguously reveal each cloud's direction of motion and likely location. In galaxy disks, we see clouds with low velocity dispersions, low line of sight velocities and a lack of any systemic inflow or outflow. In galactic cores, we find high velocity dispersion clouds inflowing at up to 550 km/s. This provides observational evidence in favour of cold accretion onto galactic centres, which likely contributes to the fuelling of active galactic nuclei. We also see a wide range in the CO(2-1)/CO(1-0) ratios of the absorption lines. This is likely the combined effect of hierarchical substructure within the molecular clouds and continuum sources which vary in size with frequency., Comment: Submitted to MNRAS
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- 2024
19. SDHDF: A new file format for spectral-domain radio astronomy data
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Toomey, L. J., Hobbs, G., Price, D. C., Dawson, J. R., Wenger, T., Lagoy, D., Staveley-Smith, L., Green, J. A., Carretti, E., Hafner, A., Huynh, M., Kaczmarek, J., Mader, S., McIntyre, V., Reynolds, J., Robishaw, T., Sarkissian, J., Thompson, A., Tremblay, C., and Zic, A.
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Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
Radio astronomy file formats are now required to store wide frequency bandwidths and multiple simultaneous receiver beams and must be able to account for versatile observing modes and numerous calibration strategies. The need to capture and archive high-time and high frequency-resolution data, along with the comprehensive metadata that fully describe the data, implies that a new data format and new processing software are required. This requirement is suited to a well-defined, hierarchically-structured and flexible file format. In this paper we present the Spectral-Domain Hierarchical Data Format (`SDHDF') -- a new file format for radio astronomy data, in particular for single dish or beam-formed data streams. Since 2018, SDHDF has been the primary format for data products from the spectral-line and continuum observing modes at Murriyang, the CSIRO Parkes 64-m radio telescope, and we demonstrate that this data format can also be used to store observations of pulsars and fast radio bursts., Comment: Supplementary material (SDHDF definition): https://ars.els-cdn.com/content/image/1-s2.0-S2213133724000192-mmc1.pdf
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- 2024
- Full Text
- View/download PDF
20. The Gaia white dwarf revolution
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Tremblay, Pier-Emmanuel, Bédard, Antoine, O'Brien, Mairi W., Munday, James, Elms, Abbigail K., Fusillo, Nicola Pietro Gentillo, and Sahu, Snehalata
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
This review highlights the role of the Gaia space mission in transforming white dwarf research. These stellar remnants constitute 5-7% of the local stellar population in volume, yet before Gaia the lack of trigonometric parallaxes hindered their identification. The mission's Data Release 2 in 2018 provided the first unbiased colour-absolute magnitude diagram of the local stellar population, identifying 260,000 white dwarfs, with the number later increasing to over 355,000 in Data Release 3. Since then, more than 400 white dwarf studies have made critical use of Gaia data, establishing it as a fundamental resource for white dwarf identification, fundamental parameter determination and more recently spectral type characterisation. The review underscores the routine reliance on Gaia parallaxes and extensive use of its photometry in white dwarf surveys. We also discuss recent discoveries firmly grounded in Gaia data, including white dwarf mergers, exotic compact binaries and evolved planetary systems., Comment: Accepted to New Astronomy Reviews (Special Issue "Gaia, the first crop of discoveries")
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- 2024
21. Bosonic Pauli+: Efficient Simulation of Concatenated Gottesman-Kitaev-Preskill Codes
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Hopfmueller, Florian, Tremblay, Maxime, St-Jean, Philippe, Royer, Baptiste, and Lemonde, Marc-Antoine
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Quantum Physics - Abstract
A promising route towards fault-tolerant quantum error correction is the concatenation of a Gottesman-Kitaev-Preskill (GKP) code with a qubit code. Development of such concatenated codes requires simulation tools which realistically model noise, while being able to simulate the dynamics of many modes. However, so far, large-scale simulation tools for concatenated GKP codes have been limited to idealized noise models and GKP code implementations. Here, we introduce the Bosonic Pauli+ model (BP+), which can be simulated efficiently for a large number of modes, while capturing the rich dynamics in the bosonic multi-mode Hilbert space. We demonstrate the method by simulating a hybrid surface code, where the data qubits are finite-energy GKP qubits stabilized using the small-Big-small (sBs) protocol, and the syndrome qubits are standard two-level systems. Using BP+, we present logical error rates of such an implementation. Confidence in the accuracy of the method is gained by comparing its predictions with full time evolution simulations for several relevant quantum circuits. While developed specifically for GKP qubits stabilized using the sBs protocol, the mathematical structure of BP+ is generic and may be applicable also to the simulation of concatenations using other bosonic codes., Comment: v2: added reference. 21 pages + references + appendices, 11 figures
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- 2024
22. SuNeRF: 3D reconstruction of the solar EUV corona using Neural Radiance Fields
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Jarolim, Robert, Tremblay, Benoit, Muñoz-Jaramillo, Andrés, Bintsi, Kyriaki-Margarita, Jungbluth, Anna, Santos, Miraflor, Vourlidas, Angelos, Mason, James P., Sundaresan, Sairam, Downs, Cooper, and Caplan, Ronald M.
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
To understand its evolution and the effects of its eruptive events, the Sun is permanently monitored by multiple satellite missions. The optically-thin emission of the solar plasma and the limited number of viewpoints make it challenging to reconstruct the geometry and structure of the solar atmosphere; however, this information is the missing link to understand the Sun as it is: a three-dimensional evolving star. We present a method that enables a complete 3D representation of the uppermost solar layer (corona) observed in extreme ultraviolet (EUV) light. We use a deep learning approach for 3D scene representation that accounts for radiative transfer, to map the entire solar atmosphere from three simultaneous observations. We demonstrate that our approach provides unprecedented reconstructions of the solar poles, and directly enables height estimates of coronal structures, solar filaments, coronal hole profiles, and coronal mass ejections. We validate the approach using model-generated synthetic EUV images, finding that our method accurately captures the 3D geometry of the Sun even from a limited number of 32 ecliptic viewpoints ($|\text{latitude}| \leq 7^\circ$). We quantify uncertainties of our model using an ensemble approach that allows us to estimate the model performance in absence of a ground-truth. Our method enables a novel view of our closest star, and is a breakthrough technology for the efficient use of multi-instrument datasets, which paves the way for future cluster missions.
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- 2024
- Full Text
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23. Observational Signatures of AGN Feedback in the Morphology and the Ionization States of Milky Way-like Galaxies
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Qutob, Nadia, Emami, Razieh, Su, Kung-Yi, Smith, Randall, Hernquist, Lars, Triani, Dian P., Hummels, Cameron, Fielding, Drummond, Hopkins, Philip F., Somerville, Rachel S., Ballantyne, David R., Vogelsberger, Mark, Tremblay, Grant, Steiner, James F., Finkbeiner, Douglas, Narayan, Ramesh, Park, Minjung, Grindlay, Josh, Natarajan, Priyamvada, Hayward, Christopher C., Kereš, Dušan, Ponnada, Sam B., Belli, Sirio, Davies, Rebecca, Maheson, Gabriel, Bugiani, Letizia, and Li, Yijia
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We make an in-depth analysis of different AGN jet models' signatures, inducing quiescence in galaxies with a halo mass of $10^{12} M_\odot$. Three jet models, including cosmic ray-dominant, hot thermal, and precessing kinetic jets, are studied at two energy flux levels each, compared to a jet-free, stellar feedback-only simulation. We examine the distribution of Mg II, O VI, and O VIII ions, alongside gas temperature and density profiles. Low-energy ions, like Mg II, concentrate in the ISM, while higher energy ions, e.g., O VIII, prevail at the AGN jet cocoon's edge. High-energy flux jets display an isotropic ion distribution with lower overall density. High-energy thermal or cosmic ray jets pressurize at smaller radii, significantly suppressing core density. The cosmic ray jet provides extra pressure support, extending cool and warm gas distribution. A break in the ion-to-mass ratio slope in O VI and O VIII is demonstrated in the ISM-to-CGM transition (between 10-30 kpc), growing smoothly towards the CGM at greater distances., Comment: 17 pages, 13 figures
- Published
- 2023
24. Introducing the concept of the Widom line in the QCD phase diagram
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Sordi, G. and Tremblay, A. -M. S.
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High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
Critical phenomena emerging from the critical end point of a first-order transition are ubiquitous in nature. Here we bring the concept of a supercritical crossover, the Widom line, initially developed in the context of fluids, into the interacting matter described by quantum chromodynamics (QCD). We show that the existence of the putative critical end point between hadron gas and quark-gluon plasma in the temperature versus chemical potential of the QCD phase diagram implies the existence of a Widom line emerging from it in the supercritical region. We survey the thermodynamic anomalies already identified in simplified theoretical models of QCD exhibiting a critical end point, to show that they can be interpreted in terms of a Widom line. Then we suggest possible directions where the Widom line concept could provide new light on the QCD phase diagram., Comment: 8 pages, 5 figures; accepted version
- Published
- 2023
- Full Text
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25. Two $T$-linear scattering rate regimes in the triangular lattice Hubbard model
- Author
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Fournier, Jérôme, Downey, Pierre-Olivier, Hébert, Charles-David, Charlebois, Maxime, and Tremblay, André-Marie
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Condensed Matter - Strongly Correlated Electrons - Abstract
In recent years, the $T$-linear scattering rate found at low temperatures, defining the strange metal phase of cuprates, has been a subject of interest. Since a wide range of materials have a scattering rate that obeys the equation $ \hbar / \tau \approx k_B T$, the idea of a universal Planckian limit on the scattering rate has been proposed. However, there is no consensus on proposed theories yet. In this work, we present our results for the $T$-linear scattering rate in the triangular lattice Hubbard model obtained using the dynamical cluster approximation. We find two regions with $T$-linear scattering rate in the $T$ -- $p$ phase diagram: one emerges from the pseudogap to correlated Fermi liquid phase transition at low doping, whereas the other is solely caused by large interaction strength at large doping.
- Published
- 2023
26. Advancing solar magnetic field extrapolations through multi-height magnetic field measurements
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Jarolim, Robert, Tremblay, Benoit, Rempel, Matthias, Molnar, Momchil, Veronig, Astrid M., Thalmann, Julia K., and Podladchikova, Tatiana
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
Non-linear force-free extrapolations are a common approach to estimate the 3D topology of coronal magnetic fields based on photospheric vector magnetograms. The force-free assumption is a valid approximation at coronal heights, but for the dense plasma conditions in the lower atmosphere, this assumption is not satisfied. In this study, we utilize multi-height magnetic field measurements in combination with physics-informed neural networks to advance solar magnetic field extrapolations. We include a flexible height-mapping, which allows us to account for the different formation heights of the observed magnetic field measurements. The comparison to analytical and simulated magnetic fields demonstrates that including chromospheric magnetic field measurements leads to a significant improvement of our magnetic field extrapolations. We also apply our method to chromospheric line-of-sight magnetograms, from the Vector Spectromagnetograph (VSM) on the Synoptic Optical Long-term Investigations of the Sun (SOLIS) observatory, in combination with photospheric vector magnetograms, from the Helioseismic Magnetic Imager (HMI) onboard the Solar Dynamic Observatory (SDO). The comparison to observations in extreme ultraviolet wavelengths shows that the additional chromospheric information leads to a better agreement with the observed coronal structures. In addition, our method intrinsically provides an estimate of the corrugation of the observed magnetograms. With this new approach, we make efficient use of multi-height magnetic field measurements and advance the realism of coronal magnetic field simulations.
- Published
- 2023
27. 'Beads on a String' Star Formation Tied to one of the most Powerful AGN Outbursts Observed in a Cool Core Galaxy Cluster
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Omoruyi, Osase, Tremblay, Grant R., Combes, Francoise, Davis, Timothy A., Gladders, Michael D., Vikhlinin, Alexey, Nulsen, Paul, Kharb, Preeti, Baum, Stefi A., O'Dea, Christopher P., Sharon, Keren, Terrazas, Bryan A., Nevin, Rebecca, Schechter, Aimee L., Zuhone, John A., McDonald, Michael, Dahle, Håkon, Bayliss, Matthew B., Connor, Thomas, Florian, Michael, Rigby, Jane R., and Vaddi, Sravani
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
With two central galaxies engaged in a major merger and a remarkable chain of 19 young stellar superclusters wound around them in projection, the galaxy cluster SDSS J1531+3414 ($z=0.335$) offers an excellent laboratory to study the interplay between mergers, AGN feedback, and star formation. New Chandra X-ray imaging reveals rapidly cooling hot ($T\sim 10^6$ K) intracluster gas, with two "wings" forming a concave density discontinuity near the edge of the cool core. LOFAR $144$ MHz observations uncover diffuse radio emission strikingly aligned with the "wings," suggesting that the "wings" are actually the opening to a giant X-ray supercavity. The steep radio emission is likely an ancient relic of one of the most energetic AGN outbursts observed, with $4pV > 10^{61}$ erg. To the north of the supercavity, GMOS detects warm ($T\sim 10^4$ K) ionized gas that enshrouds the stellar superclusters but is redshifted up to $+ 800$ km s$^{-1}$ with respect to the southern central galaxy. ALMA detects a similarly redshifted $\sim 10^{10}$ M$_\odot$ reservoir of cold ($T\sim 10^2$ K) molecular gas, but it is offset from the young stars by $\sim 1{-}3$ kpc. We propose that the multiphase gas originated from low-entropy gas entrained by the X-ray supercavity, attribute the offset between the young stars and the molecular gas to turbulent intracluster gas motions, and suggest that tidal interactions stimulated the "beads on a string" star formation morphology., Comment: Accepted by ApJ, 36 pages, 23 figures
- Published
- 2023
28. Strontium Ferrite Under Pressure: Potential Analogue to Strontium Ruthenate
- Author
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Kazemi-Moridani, Azin, Beck, Sophie, Hampel, Alexander, Tremblay, A. -M. S., Côté, Michel, and Gingras, Olivier
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
Despite the significant attention it has garnered over the last thirty years, the paradigmatic material strontium ruthenate remains the focus of critical questions regarding strongly correlated materials. As an alternative platform to unravel some of its perplexing characteristics, we propose to study the isostructural and more correlated material strontium ferrite. Using density functional theory combined with dynamical mean-field theory, we attribute the experimentally observed insulating behavior at zero pressure to strong local electronic correlations generated by Mott and Hund's physics. At high pressure, our simulations reproduce the reported insulator-to-metal transition around 18 GPa. Along with distinctive features of a Hund's metal, the resulting metallic state is found to display an electronic structure analogous to that of strontium ruthenate, suggesting that it could exhibit similar low-energy properties., Comment: 7 pages, 3 figures + 8 pages, 4 figures
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- 2023
- Full Text
- View/download PDF
29. The 40 pc sample of white dwarfs from Gaia
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O'Brien, Mairi W., Tremblay, P. -E., Klein, B. L., Koester, D., Melis, C., Bédard, A., Cukanovaite, E., Cunningham, T., Doyle, A. E., Gänsicke, B. T., Fusillo, N. P. Gentile, Hollands, M. A., McCleery, J., Pelisoli, I., Toonen, S., Weinberger, A. J., and Zuckerman, B.
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
We present a comprehensive overview of a volume-complete sample of white dwarfs located within 40 pc of the Sun, a significant proportion of which were detected in Gaia Data Release 3 (DR3). Our DR3 sample contains 1076 spectroscopically confirmed white dwarfs, with just five candidates within the volume remaining unconfirmed (more than 99 per cent spectroscopic completeness). Additionally, 28 white dwarfs were not in our initial selection from Gaia DR3, most of which are in unresolved binaries. We use Gaia DR3 photometry and astrometry to determine a uniform set of white dwarf parameters, including mass, effective temperature, and cooling age. We assess the demographics of the 40 pc sample, specifically magnetic fields, binarity, space density and mass distributions., Comment: Accepted for publication in MNRAS. 24 pages, 25 figures
- Published
- 2023
- Full Text
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30. Affordance norms for 2825 concrete nouns
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Maxwell, Nicholas P., Huff, Mark J., Hajnal, Alen, Namias, Jacob M., Blau, Julia J. C., Day, Brian, Marsh, Kerry L., Meagher, Benjamin R., Shelley-Tremblay, John F., Thomas, Gray F., and Wagman, Jeffrey B.
- Published
- 2024
- Full Text
- View/download PDF
31. Predictive Value of C-Reactive Protein for Infectious Complications After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: A Single-Center Prospective Study
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Charbonneau, Janyssa, Brind’Amour, Alexandre, Sideris, Lucas, Piedimonte, Sabrina, Soucisse, Mikaël, Singbo, Narcisse, Tremblay, Jean-François, Leblanc, Guy, Fortin, Suzanne, De Guerké, Lara, Auclair, Marie-Hélène, and Gervais, Mai-Kim
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- 2024
- Full Text
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32. “It would Never have Happened Without the Pandemic”: Understanding the Lived Experience of Individuals who Increased Their Online Gambling Participation
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Savard, Annie-Claude, Kairouz, Sylvia, Nadeau-Tremblay, Juliette, Brodeur, Magaly, Ferland, Francine, French, Martin, Morvannou, Adèle, Blanchette-Martin, Nadine, Dufour, Magali, VanMourik, Valérie, and Monson, Eva
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- 2024
- Full Text
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33. Predicting efficacy assessment of combined treatment of radiotherapy and nivolumab for NSCLC patients through virtual clinical trials using QSP modeling
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Schirru, Miriam, Charef, Hamza, Ismaili, Khalil-Elmehdi, Fenneteau, Frédérique, Zugaj, Didier, Tremblay, Pierre-Olivier, and Nekka, Fahima
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- 2024
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34. The mental health of staff at violence against women organizations during the COVID-19 pandemic: Findings from a mixed-methods study of service providers in Canada’s largest city
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Steele, Bridget, Shastri, Priya, Moses, Catherine, Tremblay, Elizabeth, Arcenal, Monique, O’Campo, Patricia, Mason, Robin, Du Mont, Janice, Hujbregts, Maria, Sim, Amanda, and Yakubovich, Alexa R.
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- 2024
- Full Text
- View/download PDF
35. Mechanical efficiency: associations with body composition and glycemic profile in healthy adults
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Marin-Couture, Elisa, Pérusse, Louis, Bouchard, Claude, Schrauwen, Patrick, Joanisse, Denis R., and Tremblay, Angelo
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- 2024
- Full Text
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36. Rock avalanches in northeastern Baffin Island, Canada: understanding low occurrence amid high hazard potential
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Matthew, Maureen C., Gosse, John C., Hermanns, Reginald L., Normandeau, Alexandre, and Tremblay, Tommy
- Published
- 2024
- Full Text
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37. Cost-Effectiveness of Plasma Microbial Cell-Free DNA Sequencing When Added to Usual Care Diagnostic Testing for Immunocompromised Host Pneumonia
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Sutton, Andrew J., Lupu, Daniel S., Bergin, Stephen P., Holland, Thomas L., McAdams, Staci A., Dadwal, Sanjeet S., Nguyen, Khoi, Nolte, Frederick S., Tremblay, Gabriel, and Perkins, Bradley A.
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- 2024
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38. CEO bias and the degree of industry competition
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Tremblay, Victor J.
- Published
- 2024
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39. Toward Greater Clarity in Defining and Understanding Nonattachment
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Tremblay, Lindsay, Van Gordon, William, and Elander, James
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- 2024
- Full Text
- View/download PDF
40. Equivalent thrombotic risk with Warfarin, Dabigatran, or Enoxaparin after failure of initial direct oral anticoagulation (DOAC) therapy
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Shyu, Margaret, Liu, Angela, Srikureja, Anya, Gregorian, Alison, Srisuwananukorn, Andrew, Tremblay, Douglas, and Naymagon, Leonard
- Published
- 2024
- Full Text
- View/download PDF
41. Living ethics: a stance and its implications in health ethics
- Author
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Racine, Eric, Ji, Sophie, Badro, Valérie, Bogossian, Aline, Bourque, Claude Julie, Bouthillier, Marie-Ève, Chenel, Vanessa, Dallaire, Clara, Doucet, Hubert, Favron-Godbout, Caroline, Fortin, Marie-Chantal, Ganache, Isabelle, Guernon, Anne-Sophie, Montreuil, Marjorie, Olivier, Catherine, Quintal, Ariane, Senghor, Abdou Simon, Stanton-Jean, Michèle, Martineau, Joé T., Talbot, Andréanne, and Tremblay, Nathalie
- Published
- 2024
- Full Text
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42. Filial Trauma: The Experience of Adoptive Parents of Children with Complex Behavioral and Relational Problems
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Tremblay, Karine and Pagé, Geneviève
- Published
- 2024
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43. Input Processing and the Acquisition of Phonology
- Author
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Tremblay, Annie, primary
- Published
- 2024
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44. Bioelectronic Medicine: a multidisciplinary roadmap from biophysics to precision therapies.
- Author
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González-González, María, Conde, Silvia, Latorre, Ramon, Thébault, Stéphanie, Pratelli, Marta, Spitzer, Nicholas, Verkhratsky, Alexei, Tremblay, Marie-Ève, Akcora, Cuneyt, Hernández-Reynoso, Ana, Ecker, Melanie, Coates, Jayme, Vincent, Kathleen, and Ma, Brandy
- Subjects
biocompatible materials ,bioelectronic medicine ,channel biophysics ,glia ,high throughput data ,medical devices ,neuromodulation ,neuronal plasticity - Abstract
Bioelectronic Medicine stands as an emerging field that rapidly evolves and offers distinctive clinical benefits, alongside unique challenges. It consists of the modulation of the nervous system by precise delivery of electrical current for the treatment of clinical conditions, such as post-stroke movement recovery or drug-resistant disorders. The unquestionable clinical impact of Bioelectronic Medicine is underscored by the successful translation to humans in the last decades, and the long list of preclinical studies. Given the emergency of accelerating the progress in new neuromodulation treatments (i.e., drug-resistant hypertension, autoimmune and degenerative diseases), collaboration between multiple fields is imperative. This work intends to foster multidisciplinary work and bring together different fields to provide the fundamental basis underlying Bioelectronic Medicine. In this review we will go from the biophysics of the cell membrane, which we consider the inner core of neuromodulation, to patient care. We will discuss the recently discovered mechanism of neurotransmission switching and how it will impact neuromodulation design, and we will provide an update on neuronal and glial basis in health and disease. The advances in biomedical technology have facilitated the collection of large amounts of data, thereby introducing new challenges in data analysis. We will discuss the current approaches and challenges in high throughput data analysis, encompassing big data, networks, artificial intelligence, and internet of things. Emphasis will be placed on understanding the electrochemical properties of neural interfaces, along with the integration of biocompatible and reliable materials and compliance with biomedical regulations for translational applications. Preclinical validation is foundational to the translational process, and we will discuss the critical aspects of such animal studies. Finally, we will focus on the patient point-of-care and challenges in neuromodulation as the ultimate goal of bioelectronic medicine. This review is a call to scientists from different fields to work together with a common endeavor: accelerate the decoding and modulation of the nervous system in a new era of therapeutic possibilities.
- Published
- 2024
45. Learning active tactile perception through belief-space control
- Author
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Tremblay, Jean-François, Meger, David, Hogan, Francois, and Dudek, Gregory
- Subjects
Computer Science - Robotics ,Computer Science - Artificial Intelligence - Abstract
Robots operating in an open world will encounter novel objects with unknown physical properties, such as mass, friction, or size. These robots will need to sense these properties through interaction prior to performing downstream tasks with the objects. We propose a method that autonomously learns tactile exploration policies by developing a generative world model that is leveraged to 1) estimate the object's physical parameters using a differentiable Bayesian filtering algorithm and 2) develop an exploration policy using an information-gathering model predictive controller. We evaluate our method on three simulated tasks where the goal is to estimate a desired object property (mass, height or toppling height) through physical interaction. We find that our method is able to discover policies that efficiently gather information about the desired property in an intuitive manner. Finally, we validate our method on a real robot system for the height estimation task, where our method is able to successfully learn and execute an information-gathering policy from scratch., Comment: 10 pages + references, 6 figures
- Published
- 2023
46. A massive multiphase plume of gas in Abell 2390's brightest cluster galaxy
- Author
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Rose, Tom, McNamara, B. R., Combes, F., Edge, A. C., Russell, H., Salome, P., Tamhane, P., Fabian, A. C., and Tremblay, G.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We present new ALMA CO(2-1) observations tracing $2.2 \times 10^{10}$ solar masses of molecular gas in Abell 2390's brightest cluster galaxy, where half the gas is located in a one-sided plume extending 15 kpc out from the galaxy centre. This molecular gas has a smooth and positive velocity gradient, and is receding 250 km/s faster at its farthest point than at the galaxy centre. To constrain the plume's origin, we analyse our new observations alongside existing X-ray, optical and radio data. We consider the possibility that the plume is a jet-driven outflow with lifting aided by jet inflated X-ray bubbles, is a trail of gas stripped from the main galaxy by ram pressure, or is formed of more recently cooled and infalling gas. The galaxy's star formation and gas cooling rate suggest the lifespan of its molecular gas may be low compared with the plume's age -- which would favour a recently cooled plume. Molecular gas in close proximity to the active galactic nucleus is also indicated by 250 km/s wide CO(2-1) absorption against the radio core, as well as previously detected CO(1-0) and HI absorption. This absorption is optically thick and has a line of sight velocity towards the galaxy centre of 200 km/s. We discuss simple models to explain its origin., Comment: Accepted for publication in MNRAS
- Published
- 2023
47. Initial-final mass relation from white dwarfs within 40 pc
- Author
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Cunningham, Tim, Tremblay, Pier-Emmanuel, and O'Brien, Mairi
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
We present an initial-final mass relation derived from the spectroscopically-complete volume-limited 40 pc sample of white dwarfs. The relation is modelled using population synthesis methods to derive an initial stellar population which can be fit to the observed mass distribution of white dwarfs. The population synthesis accounts for binary evolution, where higher-mass white dwarfs are more likely to be merger products than their lower-mass counterparts. Uncertainties are accounted from the initial mass function, stellar metallicity and age of the Galactic disc. We also consider biases induced by the spectral type of the white dwarf where pure-hydrogen atmosphere white dwarfs are likely to have more accurate masses, whilst the full white dwarf sample will have fewer biases arising from spectral evolution. We provide a four-piece segmented linear regression using Monte Carlo methods to sample the 1-$\sigma$ range of uncertainty on the initial stellar population. The derived initial-final mass relation provides a self-consistent determination of the progenitor mass for white dwarfs in the Solar neighbourhood which will be useful to study the local stellar formation history., Comment: Eleven pages. Accepted for publication in MNRAS
- Published
- 2023
48. Galaxy formation with Wave/Fuzzy Dark Matter: The core-halo structure
- Author
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Pozo, Alvaro, Emami, Razieh, Mocz, Philip, Broadhurst, Tom, Hernquist, Lars, Vogelsberger, Mark, Smith, Randall, Tremblay, Grant, Narayan, Ramesh, Steiner, James, Grindlay, Josh, and Smoot, George
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Dark matter-dominated cores have long been claimed for the well-studied local group dwarf galaxies. More recently, extended stellar halos have been uncovered around several of these dwarfs through deeper imaging and spectroscopy. Such core-halo structures are not a feature of conventional cold dark matter (CDM), based on collisionless particles where smooth, scale-free profiles are predicted. In contrast, smooth and prominent dark matter cores are predicted for Warm and Fuzzy/Wave Dark Matter (WDM/$\psi$DM) respectively. The question arises to what extent the visible stellar profiles should reflect this dark matter core structure. Here we compare cosmological hydrodynamical simulations of CDM, WDM $\&$ $\psi$DM, aiming to predict the stellar profiles for these three DM scenarios. We show that cores surrounded by extended halos are distinguishable for WDM and $\psi$DM, with the most prominent cores in the case of $\psi$DM, where the stellar density is enhanced in the core due to the presence of the relatively dense soliton. Our analysis demonstrates that such behavior does not appear in CDM, implying that the small-scale cut-off in the power spectrum present for WDM and $\psi$DM provides a core-halo transition. Consequently, we estimate the mass of the $\psi$DM particle at this core-halo transition point. Furthermore, we observe the anticipated asymmetry for $\psi$DM due to the soliton's random walk, a distinctive characteristic not found in the symmetric distributions of stars in Warm and CDM models., Comment: 17 pages and 15 figures
- Published
- 2023
49. Autonomous quantum error correction of Gottesman-Kitaev-Preskill states
- Author
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Lachance-Quirion, Dany, Lemonde, Marc-Antoine, Simoneau, Jean Olivier, St-Jean, Lucas, Lemieux, Pascal, Turcotte, Sara, Wright, Wyatt, Lacroix, Amélie, Fréchette-Viens, Joëlle, Shillito, Ross, Hopfmueller, Florian, Tremblay, Maxime, Frattini, Nicholas E., Lemyre, Julien Camirand, and St-Jean, Philippe
- Subjects
Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
The Gottesman-Kitaev-Preskill (GKP) code encodes a logical qubit into a bosonic system with resilience against single-photon loss, the predominant error in most bosonic systems. Here we present experimental results demonstrating quantum error correction of GKP states based on reservoir engineering of a superconducting device. Error correction is made autonomous through an unconditional reset of an auxiliary transmon qubit. The lifetime of the logical qubit is shown to be increased from quantum error correction, therefore reaching the point at which more errors are corrected than generated., Comment: 6 pages, 3 figures + 26 pages, 12 figures
- Published
- 2023
50. COSMIC: An Ethernet-based Commensal, Multimode Digital Backend on the Karl G. Jansky Very Large Array for the Search for Extraterrestrial Intelligence
- Author
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Tremblay, Chenoa D., Varghese, Savin Shynu, Hickish, Jack, Demorest, Paul, Ng, Cherry, Siemion, Andrew P. V., Czech, Daniel, Donnachie, Ross A., Fahar, Wael, Gajjr, Vishal, Lebofsky, Matt, MacMahon, David E., Myburgh, Talon, Ruzindana, Mark, Bright, Joseph S., Erickson, Alan, and Lacker, Kevin
- Subjects
Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The primary goal of the search for extraterrestrial intelligence (SETI) is to gain an understanding of the prevalence of technologically advanced beings (organic or inorganic) in the Galaxy. One way to approach this is to look for technosignatures: remotely detectable indicators of technology, such as temporal or spectral electromagnetic emissions consistent with an artificial source. With the new Commensal Open-Source Multimode Interferometer Cluster (COSMIC) digital backend on the Karl G. Jansky Very Large Array (VLA), we aim to conduct a search for technosignatures that is significantly larger, more sensitive, and more efficient than previously attempted. The COSMIC system is currently operational on the VLA, recording data, and designed with the flexibility to provide user-requested modes. This paper describes the hardware system design, the current software pipeline, and plans for future development., Comment: 30 pages, 17 figures. Submitted to AJ
- Published
- 2023
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