Fluctuation-dissipation ratios in the dynamics of self-assembly

We consider two seemingly very different self-assembly processes: formation of viral capsids, and crystallization of sticky discs. At low temperatures, assembly is ineffective, since there are many metastable disordered states, which are a source of kinetic frustration. We use fluctuation-dissipation ratios to extract information about the degree of this frustration. We show that our analysis is a useful indicator of the long term fate of the system, based on the early stages of assembly.Comment: 8 pages, 6 figure

Emergence of a tunable crystalline order in a Floquet-Bloch system from a parametric instability

Parametric instabilities in interacting systems can lead to the appearance of new structures or patterns. In quantum gases, two-body interactions are responsible for a variety of instabilities that depend on the characteristics of both trapping and interactions. We report on the Floquet engineering of such instabilities, on a Bose-Einstein condensate held in a time-modulated optical lattice. The modulation triggers a destabilization of the condensate into a state exhibiting a density modulation with a new spatial periodicity. This new crystal-like order directly depends on the modulation parameters: the interplay between the Floquet spectrum and interactions generates narrow and adjustable instability regions, leading to the growth, from quantum or thermal fluctuations, of modes with a density modulation non commensurate with the lattice spacing. This study demonstrates the production of metastable exotic states of matter through Floquet engineering, and paves the way for further studies of dissipation in the resulting phase, and of similar phenomena in other geometries.Comment: 12 pages, 9 figure

Ising and Potts Models on Quenched Random Gravity Graphs

We report on single-cluster Monte Carlo simulations of the Ising, 4-state Potts and 10-state Potts models on quenched ensembles of planar, tri-valent random graphs. We confirm that the first-order phase transition of the 10-state Potts model on regular 2D lattices is softened by the quenched connectivity disorder represented by the random graphs and that the exponents of the Ising and 4-state Potts models are altered from their regular lattice counterparts. The behaviour of spin models on such graphs is thus more analogous to models with quenched bond disorder than to Poisonnian random lattices, where regular lattice critical behaviour persists. Using a wide variety of estimators we measure the critical exponents for all three models, and compare the exponents with predictions derived from taking a quenched limit in the KPZ formula for the Ising and 4-state Potts models. Earlier simulations suggested that the measured values for the 10-state Potts model were very close to the predicted quenched exponents of the {\it four}-state Potts models. The analysis here, which employs a much greater range of estimators and also benefits from greatly improved statistics, still supports these numerical values.Comment: 14 pages (latex) + 6 latex tables + 5 figure

Physical Characterization of 2015 JD(1) : A Possibly Inhomogeneous Near-Earth Asteroid

The surfaces of airless bodies such as asteroids are exposed to many phenomena that can alter their physical properties. Bennu, the target of the OSIRIS-REx mission, has demonstrated how complex the surface of a small body can be. In 2019 November, the potentially hazardous asteroid 2015 JD(1) experienced a close approach of 0.033 1 au from the Earth. We present results of the physical characterization of 2015 JD(1) based on ground-based radar, spectroscopy, and photometric observations acquired during 2019 November. Radar polarimetry measurements from the Arecibo Observatory indicate a morphologically complex surface. The delay-Doppler images reveal a contact binary asteroid with an estimated visible extent of similar to 150 m. Our observations suggest that 2015 JD(1) is an E-type asteroid with a surface composition similar to aubrites, a class of differentiated enstatite meteorites. The dynamical properties of 2015 JD(1) suggest that it came from the nu (6) resonance with Jupiter, and spectral comparison with major E-type bodies suggests that it may have been derived from a parental body similar to the progenitor of the E-type (64) Angelina. Significantly, we find rotational spectral variation across the surface of 2015 JD(1) from the red to blue spectral slope. Our compositional analysis suggests that the spectral slope variation could be due to the lack of iron and sulfides in one area of the surface of 2015 JD(1) and/or differences in grain sizes.Peer reviewe

Physical Characterization of 2015 JD(1) : A Possibly Inhomogeneous Near-Earth Asteroid

The surfaces of airless bodies such as asteroids are exposed to many phenomena that can alter their physical properties. Bennu, the target of the OSIRIS-REx mission, has demonstrated how complex the surface of a small body can be. In 2019 November, the potentially hazardous asteroid 2015 JD(1) experienced a close approach of 0.033 1 au from the Earth. We present results of the physical characterization of 2015 JD(1) based on ground-based radar, spectroscopy, and photometric observations acquired during 2019 November. Radar polarimetry measurements from the Arecibo Observatory indicate a morphologically complex surface. The delay-Doppler images reveal a contact binary asteroid with an estimated visible extent of similar to 150 m. Our observations suggest that 2015 JD(1) is an E-type asteroid with a surface composition similar to aubrites, a class of differentiated enstatite meteorites. The dynamical properties of 2015 JD(1) suggest that it came from the nu (6) resonance with Jupiter, and spectral comparison with major E-type bodies suggests that it may have been derived from a parental body similar to the progenitor of the E-type (64) Angelina. Significantly, we find rotational spectral variation across the surface of 2015 JD(1) from the red to blue spectral slope. Our compositional analysis suggests that the spectral slope variation could be due to the lack of iron and sulfides in one area of the surface of 2015 JD(1) and/or differences in grain sizes.Peer reviewe

A Pitfall in the Diagnosis of Unresectable Liver Metastases: Multiple Bile Duct Hamartomas (von Meyenburg Complexes)

Von Meyenburg complexes (VMC) are a cluster of benign liver malformations including biliary cystic lesions, with congenital fibrocollagenous stroma. This rare entity can mimick multiple secondary hepatic lesions. We report a case of a 56-year-old woman who had multiples liver lesions 12 years after operation for breast cancer. Biopsy of the hepatic lesion confirmed the diagnosis of VMC. Preoperative discovery of multiple gray-white nodular lesions scattered on the surface of the liver should not always contraindicate curative liver resection. The diagnosis of VMC should be known and confirmed with liver biopsy

Modélisation de la ségrégation solutale et application à la purification du silicium photovoltaïque

La purification du silicium joue un rôle essentiel pour la production de cellules photovoltaïques. Dans le but de diminuer le coût et l'impact environnemental associés à cette étape, un procédé de purification alternatif est en développement à l'INES (Institut National de l'Energie Solaire). L'une des étapes de ce procédé consiste à éliminer les impuretés métalliques par ségrégation lors d'un processus de solidification dirigée. L'efficacité de ce procédé est directement liée au transport convectif des impuretés dans la phase liquide. Notre étude porte donc sur la modélisation du phénomène de ségrégation et sur l'optimisation du procédé par un système de brassage mécanique. Une étude numérique basée sur des simulations en régime transitoire a été réalisée. Dans un premier temps, des simulations de ségrégation en 2D ont permis de confirmer le domaine de validité d'un modèle analytique de ségrégation. Puis, dans un second temps, l'écoulement généré par le système de brassage a été caractérisé à l'aide de simulations numériques en 3D. Ces résultats numériques ont pu être comparés à des mesures de champ de vitesse réalisées par PIV sur un dispositif expérimental en eau

Ising model on 3D random lattices: A Monte Carlo study

We report single-cluster Monte Carlo simulations of the Ising model on three-dimensional Poissonian random lattices with up to 128,000 approx. 503 sites which are linked together according to the Voronoi/Delaunay prescription. For each lattice size quenched averages are performed over 96 realizations. By using reweighting techniques and finite-size scaling analyses we investigate the critical properties of the model in the close vicinity of the phase transition point. Our random lattice data provide strong evidence that, for the available system sizes, the resulting effective critical exponents are indistinguishable from recent high-precision estimates obtained in Monte Carlo studies of the Ising model and \phi^4 field theory on three-dimensional regular cubic lattices.Comment: 35 pages, LaTex, 8 tables, 8 postscript figure

Non-linear susceptibilities of spherical models

The static and dynamic susceptibilities for a general class of mean field random orthogonal spherical spin glass models are studied. We show how the static and dynamical properties of the linear and nonlinear susceptibilities depend on the behaviour of the density of states of the two body interaction matrix in the neighbourhood of the largest eigenvalue. Our results are compared with experimental results and also with those of the droplet theory of spin glasses.Comment: 20 pages, 2 fig

The UQAM Mummy – The Use of Non-Destructive Imaging to Reconstruct an Ancient Osteobiography and to Document Modern Malfeasance

An Egyptian mummy and her coffin dating to the 26th Dynasty were donated to the École de Beaux Arts in Montreal in 1927. This mummy has been in the collection of the Université du Québec à Montréal since 1967. Inscriptions on the elaborate coffin identify the individual as Hetep-Bastet. In 1969, the mummy was attacked by a protester, who caused extensive damage. The mummy was scanned once over a decade ago. However, computed tomography (CT) technology has advanced a great deal since that time, and some conclusions reached were somewhat suspect (e.g. that she suffered from a large dental abscess caused by “drinking too much beer”). Thus, when Hetep-Bastet was transported to Gatineau in the fall of 2008 to be part of the “Tombs for Eternity” exhibit at the Canadian Museum of Civilization, we took the opportunity to rescan her. The specific goals of our study were: to assess the damage done by the protester in 1969 to investigate the specific details of how she was mummified as part of an ongoing study of variability in mummification practice to gather osteological and paleopathological data in order to reconstruct her osteobiography to segment the skull from the CT data in order to create a facial reconstruction to examine her coffin as part of an ongoing study of the use of CT scans to characterize different materials associated with Egyptian mummies Damag