Long-lived Anatexis in the Exhumed Middle Crust from the Torngat Orogen and Eastern Core Zone: Constraints from Geochronology, Petrochronology, and Phase Equilibria Modeling

The Torngat Orogen (southeastern Churchill Province, Canada) is a transpressional Paleoproterozoic orogen resulting from the collision between the North Atlantic Craton and the Core Zone (an Archean micro-continent) during the larger-scale Trans-Hudson Orogeny. The doubly-vergent Torngat Orogen is mainly exposed as granulite-facies metamorphic rocks and migmatites within a narrow (~150 km) belt. High-T metamorphic mineral assemblages (sillimanite stability field) are regionally overprinted by amphibolite-facies, high-strain, strike-slip shear zones. The development of granulite-facies metamorphic conditions, extensive anatexis, and intense shear deformation in such a narrow region is anomalous even for transpressional and hot orogens (such as Paleoproterozoic orogens during the “Archean-type” to “modern-type” tectonic transition). Recent field observations indicate that anatexis also occurred in the adjacent eastern Core Zone, thus shedding doubt on the true spatial extent of Torngat metamorphism and therefore on the dimensions and shape of the orogen. Here, thermobarometry, phase equilibria modeling, and geochronology were used to investigate the timing, extent, and significance of metamorphism in the western Torngat Orogen and eastern Core Zone. The results reveal that the Torngat Orogen is larger, older, and longer-lived than previously thought. Multi-equilibria thermobarometry and phase equilibria modeling highlight a continuous increase in metamorphic conditions from the Core Zone to the Torngat granulites with no evidence of a major metamorphic break. Close-to-peak metamorphic conditions, constrained from mafic samples, gradually increases from 8.7 kbars-814°C to 10.8 kbars-914°C from west to east. Melt crystallization conditions, defined from metasedimentary rock samples, are estimated at 5.4 kbars-709°C to 8.1 kbars-823°C from west to east. Rocks from the Core Zone and Torngat Orogen appear to have followed hairpin P-T paths in the sillimanite stability field. Metamorphic zircon U-Pb ages, monazite U-Pb ages, and garnet Lu-Hf and Sm-Nd ages are consistent in both domains, confirming that the eastern Core Zone was significantly reworked during the Torngat Orogeny. Zircon and monazite ages suggest protracted metamorphic crystallization from c. 1885 to 1780 Ma. Crystallization events at c. 1860-1840 Ma and c. 1820-1800 Ma are interpreted as indicators of transpressional deformation (limited to the Torngat granulitic domains) and melt crystallization that was contemporaneous over the study area, respectively. Lu-Hf garnet geochronology reveals that garnet growth had begun by 1955-1885 Ma, potentially making the orogen at least 15 Myr older than previously thought. P-T-t-D paths support a peak-to-retrograde evolution characterized by a medium dP/dT slope (geotherm-parallel) without isothermal decompression. After peak metamorphic conditions were reached by 1885-1840 Ma, both domains stayed at suprasolidus conditions until 1820-1800 Ma. In light of these results, we suggest that the Torngat Orogeny produced a large mid-pressure, high-temperature terrain with crustal-scale partial melting. The entire area represents a down-to-the-east mid-crustal section that was mainly exhumed through denudation. The long duration of mid-pressure and high-temperature metamorphism in this region may be explained by its position on the eastern flank of the Ungava indentor (oblique convergence) and by the high thermal state of the lithospheric mantle. The Torngat Orogen may be intermediate between ultra-hot orogens and hot orogens, where decoupling between the hot lithosphere and crust is responsible for large-scale penetrative deformation (vise model)

RGB-D-E: Event Camera Calibration for Fast 6-DOF Object Tracking

Augmented reality devices require multiple sensors to perform various tasks such as localization and tracking. Currently, popular cameras are mostly frame-based (e.g. RGB and Depth) which impose a high data bandwidth and power usage. With the necessity for low power and more responsive augmented reality systems, using solely frame-based sensors imposes limits to the various algorithms that needs high frequency data from the environement. As such, event-based sensors have become increasingly popular due to their low power, bandwidth and latency, as well as their very high frequency data acquisition capabilities. In this paper, we propose, for the first time, to use an event-based camera to increase the speed of 3D object tracking in 6 degrees of freedom. This application requires handling very high object speed to convey compelling AR experiences. To this end, we propose a new system which combines a recent RGB-D sensor (Kinect Azure) with an event camera (DAVIS346). We develop a deep learning approach, which combines an existing RGB-D network along with a novel event-based network in a cascade fashion, and demonstrate that our approach significantly improves the robustness of a state-of-the-art frame-based 6-DOF object tracker using our RGB-D-E pipeline.Comment: 9 pages, 9 figure

Diastereoselective Borocyclopropanation of Allylic Ethers Using a Boromethylzinc Carbenoid

A borocyclopropanation of (<i>E</i>)- and (<i>Z</i>)-allylic ethers and styrene derivatives via the Simmons–Smith reaction using a novel boromethylzinc carbenoid is described. The carbenoid precursor is prepared via a 3-step sequence from inexpensive and commercially available starting materials. This methodology allows for the preparation of 1,2,3-substituted borocyclopropanes in high yields and diastereoselectivities. Several postfunctionalization reactions were also performed to illustrate the versatility of these building blocks

Stratégies face à la crise des opioïdes : analyse des revues systématiques

Contexte : L’Amérique du Nord subit une vague sans précédent de surdoses, souvent liées aux opioïdes. Elle touche les personnes utilisatrices de drogues, mais également celles qui consomment des opioïdes prescrits. Plusieurs stratégies sont utilisées pour réduire les méfaits et les décès liés aux surdoses. Cette étude vise à identifier les stratégies nord-américaines en réponse à la crise, ainsi que les obstacles et les facilitateurs dans leur développement et leur accès.Méthodologie : Une analyse du contenu explicite de revues systématiques a été réalisée. La recherche documentaire a été faite dans les bases de données CINAHL, Medline, PsychINFO et PubMed en utilisant les lignes directrices PRISMA. Une évaluation de la qualité des articles retenus a été réalisée en utilisant l’outil d’évaluation du programme de compétences en évaluation critique (CASP).Résultats : Neuf revues systématiques ont été retenues et concernaient des stratégies ciblant : la prescription d’opioïdes ou d’alternatives ; la distribution de naloxone ; les interventions psychosociales en conjonction avec les traitements aux agonistes des opioïdes ; et la recherche sur le trouble d’utilisation de substances opioïdes. Plusieurs obstacles et éléments facilitateurs ont été identifiés en lien avec ces stratégies. Elles sont le plus souvent déployées sur les plans communautaire et social, à grande échelle, et rarement sur les plans individuel et interpersonnel.Conclusions : Cette étude a identifié des stratégies utilisées en Amérique du Nord face à la crise des opioïdes, leurs facilitateurs et leurs obstacles. À l’exception de la distribution de naloxone, les stratégies évaluées n’avaient que peu ou pas d’efficacité démontrée pour prévenir les surdoses ou les méfaits associés. Une réflexion s’impose quant à l’arrimage entre la recherche et les besoins des personnes à risque de surdose afin de réduire les complications et les décès liés aux opioïdes. Pour y arriver, il est nécessaire d’individualiser les stratégies en fonction des besoins des personnes.Background : North America is experiencing an unprecedented wave of overdoses, often related to opioids. It affects not only people who use drugs, but also those who use prescribed opioids. Several strategies are being used to reduce the harm and deaths associated with overdoses. This study aims to identify North American strategies in response to the crisis, as well as the barriers and facilitators to their development and access.Methods: A review of systematic reviews was conducted. The literature search was conducted in the CINAHL, Medline, PsychINFO and PubMed databases using PRISMA guidelines. A quality assessment of the selected articles was conducted using the Critical Appraisal Skills Program (CASP) assessment tool.Results: Nine systematic reviews were selected for strategies targeting: the prescription of opioids or alternatives; naloxone distribution ; psychosocial interventions in conjunction with opioid agonist therapy; and research on opioid use disorder. Several barriers and facilitators were identified in relation to these strategies. They are most often deployed at the community and societal levels, on a large scale, and rarely at the individual and interpersonal levels.Conclusions: This study identified strategies used in North America to address the opioid crisis, their facilitators, and barriers. Except for naloxone distribution, the strategies evaluated had little or no demonstrated effectiveness in preventing overdose or associated harms. Thought needs to be given to linking research to the needs of people at risk of overdose in order to reduce opioid-related complications and deaths. To achieve this, it is necessary to individualize strategies based on the needs of individuals.Contexto: América del Norte sufre una ola sin precedentes de sobredosis, a menudo relacionadas con los opioides, que afecta a las personas consumidoras de drogas e igualmente a quienes consumen opioides prescriptos. Se utilizan varias estrategias para reducir los daños y las muertes ligadas a las sobredosis. Este estudio tiene como objetivo la identificación de las estrategias norteamericanas en respuesta a la crisis, así como los obstáculos y los facilitadores en su desarrollo y su acceso.Metodología: Se ha llevado a cabo un análisis del contenido explícito de revisiones sistemáticas. La búsqueda documental se ha realizado en las bases de datos CINAHL, Medline, PsychINFO y PubMed, utilizando las líneas directrices de PRISMA. Se ha hecho una evaluación de la calidad de los artículos retenidos utilizando la herramienta de evaluación del programa de competencias en evaluación crítica (CASP).Resultados: Se retuvieron nueve revisiones sistemáticas concernientes a estrategias enfocadas en lo siguiente: la prescripción de opioides o de alternativas; la distribución de naloxona; las intervenciones psicosociales juntamente con los tratamientos con agonistas de los opioides y la investigación sobre el trastorno de utilización de sustancias opioides. Se identificaron numerosos obstáculos y elementos facilitadores relacionados con estas estrategias, que a menudo se aplican en los planos comunitario y social en gran escala y raramente en el plano individual o interpersonal.Conclusiones: Este estudio ha identificado estrategias utilizadas en América del Norte ante la crisis de los opioides, sus facilitadores y sus obstáculos. Con la excepción de la distribución de naloxona, las estrategias evaluadas presentaban poca o ninguna eficacia demostrada para prevenir las sobredosis o los daños relacionados. Se impone una reflexión en lo que respecta al acercamiento entre la investigación y las necesidades de las personas que están a riesgo de sobredosis para poder reducir las complicaciones y las muertes ligadas a los opioides. Para lograrlo, es necesario individualizar las estrategias en función de las necesidades de las personas

RGB-D-E: Event Camera Calibration for Fast 6-DOF Object Tracking

9 pages, 9 figuresInternational audienceAugmented reality devices require multiple sensors to perform various tasks such as localization and tracking. Currently, popular cameras are mostly frame-based (e.g. RGB and Depth) which impose a high data bandwidth and power usage. With the necessity for low power and more responsive augmented reality systems, using solely frame-based sensors imposes limits to the various algorithms that needs high frequency data from the environement. As such, event-based sensors have become increasingly popular due to their low power, bandwidth and latency, as well as their very high frequency data acquisition capabilities. In this paper, we propose, for the first time, to use an event-based camera to increase the speed of 3D object tracking in 6 degrees of freedom. This application requires handling very high object speed to convey compelling AR experiences. To this end, we propose a new system which combines a recent RGB-D sensor (Kinect Azure) with an event camera (DAVIS346). We develop a deep learning approach, which combines an existing RGB-D network along with a novel event-based network in a cascade fashion, and demonstrate that our approach significantly improves the robustness of a state-of-the-art frame-based 6-DOF object tracker using our RGB-D-E pipeline