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1. Intense alteration on early Mars revealed by high-aluminum rocks at Jezero crater

Author

C. Royer, C. C. Bedford, J. R. Johnson, B. H. N. Horgan, A. Broz, O. Forni, S. Connell, R. C. Wiens, L. Mandon, B. S. Kathir, E. M. Hausrath, A. Udry, J. M. Madariaga, E. Dehouck, R. B. Anderson, P. Beck, O. Beyssac, É. Clavé, S. M. Clegg, E. Cloutis, T. Fouchet, T. S. J. Gabriel, B. J. Garczynski, A. Klidaras, H. T. Manelski, L. Mayhew, J. Núñez, A. M. Ollila, S. Schröder, J. I. Simon, U. Wolf, K. M. Stack, A. Cousin, and S. Maurice

Subjects
Geology, QE1-996.5, Environmental sciences, GE1-350
Abstract

Abstract The NASA Perseverance rover discovered light-toned float rocks scattered across the surface of Jezero crater that are particularly rich in alumina ( ~ 35 wt% Al2O3) and depleted in other major elements (except silica). These unique float rocks have heterogeneous mineralogy ranging from kaolinite/halloysite-bearing in hydrated samples, to spinel-bearing in dehydrated samples also containing a dehydrated Al-rich phase. Here we describe SuperCam and Mastcam-Z observations of the float rocks, including the first in situ identification of kaolinite or halloysite on another planet, and dehydrated phases including spinel and apparent partially dehydroxylated kaolinite. The presence of spinel in these samples is likely detrital in origin, surviving kaolinitization, pointing to an ultramafic origin. However, the association of low hydration with increased Al2O3 abundances suggests heating-induced dehydration which could have occurred during the lithification or impact excavation of these rocks. Given the orbital context of kaolinite-bearing megabreccia in the Jezero crater rim, we propose an origin for these rocks involving intense aqueous alteration of the parent material, followed by dehydration/lithification potentially through impact processes, and dispersion into Jezero crater through flood or impact-related processes.

Published
2024
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2. Radiation-induced alteration of apatite on the surface of Mars: first in situ observations with SuperCam Raman onboard Perseverance

Author

E. Clavé, O. Beyssac, S. Bernard, C. Royer, G. Lopez-Reyes, S. Schröder, K. Rammelkamp, O. Forni, A. Fau, A. Cousin, J. A. Manrique, A. Ollila, J. M. Madariaga, J. Aramendia, S. K. Sharma, T. Fornaro, S. Maurice, R. C. Wiens, and the SuperCam Science team

Subjects
Medicine, Science
Abstract

Abstract Planetary exploration relies considerably on mineral characterization to advance our understanding of the solar system, the planets and their evolution. Thus, we must understand past and present processes that can alter materials exposed on the surface, affecting space mission data. Here, we analyze the first dataset monitoring the evolution of a known mineral target in situ on the Martian surface, brought there as a SuperCam calibration target onboard the Perseverance rover. We used Raman spectroscopy to monitor the crystalline state of a synthetic apatite sample over the first 950 Martian days (sols) of the Mars2020 mission. We note significant variations in the Raman spectra acquired on this target, specifically a decrease in the relative contribution of the Raman signal to the total signal. These observations are consistent with the results of a UV-irradiation test performed in the laboratory under conditions mimicking ambient Martian conditions. We conclude that the observed evolution reflects an alteration of the material, specifically the creation of electronic defects, due to its exposure to the Martian environment and, in particular, UV irradiation. This ongoing process of alteration of the Martian surface needs to be taken into account for mineralogical space mission data analysis.

Published
2024
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3. Astrobiological Potential of Rocks Acquired by the Perseverance Rover at a Sedimentary Fan Front in Jezero Crater, Mars

Author

T. Bosak, D. L. Shuster, E. L. Scheller, S. Siljeström, M. J. Zawaski, L. Mandon, J. I. Simon, B. P. Weiss, K. M. Stack, E. N. Mansbach, A. H. Treiman, K. C. Benison, A. J. Brown, A. D. Czaja, K. A. Farley, E. M. Hausrath, K. Hickman‐Lewis, C. D. K. Herd, J. R. Johnson, L. E. Mayhew, M. E. Minitti, K. H. Williford, B. V. Wogsland, M.‐P. Zorzano, A. C. Allwood, H. E. F. Amundsen, J. F. Bell III, K. Benzerara, S. Bernard, O. Beyssac, D. K. Buckner, M. Cable, F. Calef III, G. Caravaca, D. C. Catling, E. Clavé, E. Cloutis, B. A. Cohen, A. Cousin, E. Dehouck, A. G. Fairén, D. T. Flannery, T. Fornaro, O. Forni, T. Fouchet, E. Gibbons, F. Gomez Gomez, S. Gupta, K. P. Hand, J. A. Hurowitz, H. Kalucha, D. A. K. Pedersen, G. Lopes‐Reyes, J. N. Maki, S. Maurice, J. I. Nuñez, N. Randazzo, J. W. Rice Jr., C. Royer, M. A. Sephton, S. Sharma, A. Steele, C. D. Tate, K. Uckert, A. Udry, R. C. Wiens, and A. Williams

Subjects
Mars, sedimentary geochemistry, planetary geochemistry, origin of life, hydrothermal systems and weathering on other planets, hydrology and fluvial processes, Geology, QE1-996.5, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract The Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate‐bearing sandstone deposited above the sulfate‐bearing strata. All samples contain aqueously precipitated materials and most or all were aqueously deposited. Although the rover instruments have not confidently detected organic matter in the rocks from the fan front, the much more sensitive terrestrial instruments will still be able to search for remnants of prebiotic chemistries and past life, and study Mars's past habitability in the samples returned to Earth. The hydrated, sulfate‐bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate‐bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water. Returned sample science analyses of sulfate, carbonate, clay, phosphate and igneous minerals as well as trace metals and volatiles that are present in the samples acquired at the fan front would provide transformative insights into past habitable environments on Mars, the evolution of its magnetic field, atmosphere and climate and the past and present cycling of atmospheric and crustal water, sulfur and carbon.

Published
2024
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6. Non-Destructive, High-Resolution, Chemically Specific, 3D Nanostructure Characterization using Phase-Sensitive EUV Imaging Reflectometry

Author

Tanksalvala, Michael, Porter, Christina L., Esashi, Yuka, Wang, Bin, Jenkins, Nicholas W., Zhang, Zhe, Miley, Galen P., Knobloch, Joshua L., McBennett, Brendan, Horiguchi, Naoto, Yazdi, Sadegh, Zhou, Jihan, Jacobs, Matthew N., Bevis, Charles S., Karl Jr., Robert M., Johnsen, Peter, Ren, David, Waller, Laura, Adams, Daniel E., Cousin, Seth L., Liao, Chen-Ting, Miao, Jianwei, Gerrity, Michael, Kapteyn, Henry C., and Murnane, Margaret M.

Subjects
Physics - Optics, Physics - Applied Physics, Physics - Instrumentation and Detectors
Abstract

Next-generation nano and quantum devices have increasingly complex 3D structure. As the dimensions of these devices shrink to the nanoscale, their performance is often governed by interface quality or precise chemical or dopant composition. Here we present the first phase-sensitive extreme ultraviolet imaging reflectometer. It combines the excellent phase stability of coherent high-harmonic sources, the unique chemical- and phase-sensitivity of extreme ultraviolet reflectometry, and state-of-the-art ptychography imaging algorithms. This tabletop microscope can non-destructively probe surface topography, layer thicknesses, and interface quality, as well as dopant concentrations and profiles. High-fidelity imaging was achieved by implementing variable-angle ptychographic imaging, by using total variation regularization to mitigate noise and artifacts in the reconstructed image, and by using a high-brightness, high-harmonic source with excellent intensity and wavefront stability. We validate our measurements through multiscale, multimodal imaging to show that this technique has unique advantages compared with other techniques based on electron and scanning-probe microscopies., Comment: 47 pages, 16 figures (4 in main text, 12 supplement) 2 tables

Published
2024
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7. Network nestedness in primates: a structural constraint or a biological advantage of social complexity?

Author

Herbrich, Maxime, Cousin, Eythan, Puga-Gonzalez, Ivan, Tiddi, Barbara, Fichtel, Claudia, Crofoot, Meg, Macintosh, Andrew Jj, van de Waal, Erica, and Sueur, Cédric

Subjects
Quantitative Biology - Quantitative Methods
Abstract

This study investigates the prevalence and implications of nestedness within primate social networks, examining its relationship with cognitive and structural factors. We analysed data from 51 primate groups across 21 species, employing network analysis to evaluate nestedness and its correlation with modularity, neocortex ratio, and group size. We used Bayesian mixed effects modelling to investigate nestedness in primate social networks, controlling for phylogenetic dependencies and exploring various factors like neocortex ratio and group size. Our findings reveal a significant occurrence of nestedness in 66% of the species studied, exceeding chance expectations. This nestedness was more pronounced in groups with less steep dominance hierarchies, contrary to traditional assumptions linking it to hierarchical social structures. A notable inverse relationship between nestedness and modularity was observed, suggesting a structural trade-off in network formation. This pattern persisted even after controlling for species-specific social behaviours, indicating a general structural feature of primate networks. Surprisingly, our analysis showed no significant correlation between nestedness and neocortex ratio or group size, challenging the social brain hypothesis and suggesting a greater role for ecological factors in cognitive evolution. This study emphasises the importance of weak links in maintaining network resilience. Overall, our research provides new insights into primate social network structures, highlighting complex interplays between network characteristics and challenging existing paradigms in cognitive and evolutionary biology.

Published
2024

9. Experimentation, identification, and simulation of polymer swelling at extrusion die outlets

Author

Rabhi, Faleh, de Larochelambert, Thierry, Barriere, Thierry, Ramel, David, Cousin, Thibault, and Sahli, Mohamed

Subjects
Polyamides -- Comparative analysis, Polymer industry -- Comparative analysis, Engineering and manufacturing industries, Science and technology
Abstract

The behavior of polyamide PA12 melt extrudates at die outlets is modeled to determine swelling process and rate. It is assessed as a function of imposed input parameters, process parameters, and die geometries. The modeling is carried out using Comsol Multiphysics[R] platform to simulate the swelling; in particular, its progression in time is investigated for different extrusion process parameters. The experimental swelling observed in extrusion lines tests is compared with the Tanner and Carreau-Yasuda rheological models. A database is built up with all experiments carried out; the comparison between numerical and experimental results shows close agreement. A parametric analysis of the experimental and numerical swelling is performed. It confirms the important role of the die diameter on swelling rate, independently of shear rate. Increase in temperature lowers swelling rate at constant shear rates and geometric aspect ratio of the dies. Highlights * Experimental and numerical study of polymer swelling at capillary die outlets. * Behavior of PA12 polymer extrudate modeled to determine its swelling. * Rheological models implemented to simulate the swelling phenomenon. * Simulation results validated with experimental tests for two millimetric dies. * Influence of die geometrical parameters investigated and justified. KEYWORDS Carreau-Yasuda law, die swell, polyamide PA12, polymer extrusion, simulation, Tanner model, 1 | INTRODUCTION Swelling is a common phenomenon observed at die outlets during polymer extrusion processes. This phenomenon is complex and requires detailed knowledge of the material properties, flow, extrusion [...]

Published
2024
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14. Marrow-ablative consolidation chemotherapy and molecular targeted therapy delivered in a risk-adapted manner for newly diagnosed children with choroid plexus carcinoma: A work in progress.

Author

Yankelevich, Maxim, Zaky, Wafik, Lafay-Cousin, Lucie, Osorio, Diana, Adamski, Jenny, Kordes, Uwe, Finlay, Jonathan, Prados, Michael, and Mueller, Sabine

Subjects
Li-Fraumeni syndrome, choroid plexus carcinoma, marrow-ablative chemotherapy
Abstract

Choroid plexus carcinomas (CPC) are early childhood cancers characterized by loss of TP53 function and poor survival. We are analyzing data on TP53 status, survival, and second cancers from the largest cohort of CPC receiving chemotherapy followed by consolidation with marrow-ablative chemotherapy (HDCx). Additionally, we discuss the rationale for targeted therapies for CPC patients. Currently, 8 of the 13 with Li-Fraumeni Syndrome-associated CPC were treated and continued CPC-free, indicating that HDCx improves CPC-free survival in young children with TP53-mutated CPC. These data justify the inclusion of HDCx in the planned prospective international trial for children with TP53-mutated CPC.

Published
2024

15. Intense alteration on early Mars revealed by high-aluminum rocks at Jezero crater

Author

Royer, C., Bedford, C. C., Johnson, J. R., Horgan, B. H. N., Broz, A., Forni, O., Connell, S., Wiens, R. C., Mandon, L., Kathir, B. S., Hausrath, E. M., Udry, A., Madariaga, J. M., Dehouck, E., Anderson, R. B., Beck, P., Beyssac, O., Clavé, É., Clegg, S. M., Cloutis, E., Fouchet, T., Gabriel, T. S. J., Garczynski, B. J., Klidaras, A., Manelski, H. T., Mayhew, L., Núñez, J., Ollila, A. M., Schröder, S., Simon, J. I., Wolf, U., Stack, K. M., Cousin, A., and Maurice, S.

Published
2024
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18. Identification of microenvironment features associated with primary resistance to anti-PD-1/PD-L1 + antiangiogenesis in gastric cancer through spatial transcriptomics and plasma proteomics

Author

Cousin, Sophie, Guégan, Jean-Philippe, Shitara, Kohei, Palmieri, Lola Jade, Metges, Jean Philippe, Pernot, Simon, Fukuoka, Shota, Koyama, Shohei, Nishikawa, Hiroyoshi, Bellera, Carine A., Adenis, Antoine, Gomez-Roca, Carlos A., Cassier, Philippe Alexandre, Hollebecque, Antoine, Cantarel, Coralie, Kind, Michèle, Soubeyran, Isabelle, Vanhersecke, Lucile, Bessede, Alban, and Italiano, Antoine

Published
2024
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19. RAS-ON inhibition overcomes clinical resistance to KRAS G12C-OFF covalent blockade

Author

Nokin, Marie-Julie, Mira, Alessia, Patrucco, Enrico, Ricciuti, Biagio, Cousin, Sophie, Soubeyran, Isabelle, San José, Sonia, Peirone, Serena, Caizzi, Livia, Vietti Michelina, Sandra, Bourdon, Aurelien, Wang, Xinan, Alvarez-Villanueva, Daniel, Martínez-Iniesta, María, Vidal, August, Rodrigues, Telmo, García-Macías, Carmen, Awad, Mark M., Nadal, Ernest, Villanueva, Alberto, Italiano, Antoine, Cereda, Matteo, Santamaría, David, and Ambrogio, Chiara

Published
2024
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20. Enhanced hippocampal LTP but normal NMDA receptor and AMPA receptor function in a rat model of CDKL5 deficiency disorder

Author

Simões de Oliveira, Laura, O’Leary, Heather E., Nawaz, Sarfaraz, Loureiro, Rita, Davenport, Elizabeth C., Baxter, Paul, Louros, Susana R., Dando, Owen, Perkins, Emma, Peltier, Julien, Trost, Matthias, Osterweil, Emily K., Hardingham, Giles E., Cousin, Michael A., Chattarji, Sumantra, Booker, Sam A., Benke, Tim A., Wyllie, David J. A, and Kind, Peter C.

Published
2024
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24. Identification of CT radiomic features robust to acquisition and segmentation variations for improved prediction of radiotherapy-treated lung cancer patient recurrence

Author

Louis, Thomas, Lucia, François, Cousin, François, Mievis, Carole, Jansen, Nicolas, Duysinx, Bernard, Le Pennec, Romain, Visvikis, Dimitris, Nebbache, Malik, Rehn, Martin, Hamya, Mohamed, Geier, Margaux, Salaun, Pierre-Yves, Schick, Ulrike, Hatt, Mathieu, Coucke, Philippe, Lovinfosse, Pierre, and Hustinx, Roland

Published
2024
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28. Triangular Automata: The 256 Elementary Cellular Automata of the 2D Plane

Author

Cousin, Paul

Subjects
Nonlinear Sciences - Cellular Automata and Lattice Gases
Abstract

Triangular Automata (TA) stands for cellular automata in the triangular grid. This work focuses on the simplest type of TA called Elementary Triangular Automata (ETA). They are argued to be the two-dimensional counterpart of Wolfram's Elementary Cellular Automata. Conceptual and computational tools for their study are presented along with an initial analysis. The paper is accompanied by a website where the results can be explored interactively. The source code is available in the form of a Mathematica package.

Published
2023

29. Multilingual Audio Captioning using machine translated data

Author

Cousin, Matéo, Labbé, Étienne, and Pellegrini, Thomas

Subjects
Computer Science - Sound, Electrical Engineering and Systems Science - Audio and Speech Processing
Abstract

Automated Audio Captioning (AAC) systems attempt to generate a natural language sentence, a caption, that describes the content of an audio recording, in terms of sound events. Existing datasets provide audio-caption pairs, with captions written in English only. In this work, we explore multilingual AAC, using machine translated captions. We translated automatically two prominent AAC datasets, AudioCaps and Clotho, from English to French, German and Spanish. We trained and evaluated monolingual systems in the four languages, on AudioCaps and Clotho. In all cases, the models achieved similar performance, about 75% CIDEr on AudioCaps and 43% on Clotho. In French, we acquired manual captions of the AudioCaps eval subset. The French system, trained on the machine translated version of AudioCaps, achieved significantly better results on the manual eval subset, compared to the English system for which we automatically translated the outputs to French. This advocates in favor of building systems in a target language instead of simply translating to a target language the English captions from the English system. Finally, we built a multilingual model, which achieved results in each language comparable to each monolingual system, while using much less parameters than using a collection of monolingual systems.

Published
2023

30. Semiautomated approach focused on new genomic information results in time and effort-efficient reannotation of negative exome data

Author

Ferrer, Alejandro, Duffy, Patrick, Olson, Rory J., Meiners, Michael A., Schultz-Rogers, Laura, Macke, Erica L., Safgren, Stephanie, Morales-Rosado, Joel A., Cousin, Margot A., Oliver, Gavin R., Rider, David, Williams, Megan, Pichurin, Pavel N., Deyle, David R., Morava, Eva, Gavrilova, Ralitza H., Dhamija, Radhika, Wierenga, Klass J., Lanpher, Brendan C., Babovic-Vuksanovic, Dusica, Kaiwar, Charu, Vitek, Carolyn R., McAllister, Tammy M., Wick, Myra J., Schimmenti, Lisa A., Lazaridis, Konstantinos N., Vairo, Filippo Pinto e, and Klee, Eric W.

Published
2024
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31. Impact of trametinib on the neuropsychological profile of NF1 patients

Author

Lalancette, Eve, Cantin, Édith, Routhier, Marie-Ève, Mailloux, Chantal, Bertrand, Marie-Claude, Kiaei, Dorsa Sadat, Larouche, Valérie, Tabori, Uri, Hawkins, Cynthia, Ellezam, Benjamin, Décarie, Jean-Claude, Théoret, Yves, Métras, Marie-Élaine, McKeown, Tara, Ospina, Luis H., Vairy, Stéphanie, Ramaswamy, Vijay, Coltin, Hallie, Sultan, Serge, Legault, Geneviève, Bouffet, Éric, Lafay-Cousin, Lucie, Hukin, Juliette, Erker, Craig, Caru, Maxime, Dehaes, Mathieu, Jabado, Nada, Perreault, Sébastien, and Lippé, Sarah

Published
2024
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32. Mean-variance dynamic portfolio allocation with transaction costs: a Wiener chaos expansion approach

Author

Cousin, Areski, Lelong, Jérôme, and Picard, Tom

Subjects
Quantitative Finance - Portfolio Management, Mathematics - Probability, Quantitative Finance - Computational Finance
Abstract

This paper studies the multi-period mean-variance portfolio allocation problem with transaction costs. Many methods have been proposed these last years to challenge the famous uni-period Markowitz strategy.But these methods cannot integrate transaction costs or become computationally heavy and hardly applicable. In this paper, we try to tackle this allocation problem by proposing an innovative approach which relies on representing the set of admissible portfolios by a finite dimensional Wiener chaos expansion. This numerical method is able to find an optimal strategy for the allocation problem subject to transaction costs. To complete the study, the link between optimal portfolios submitted to transaction costs and the underlying risk aversion is investigated. Then a competitive and compliant benchmark based on the sequential uni-period Markowitz strategy is built to highlight the efficiency of our approach.

Published
2023

38. Beyond Surrogate Modeling: Learning the Local Volatility Via Shape Constraints

Author

Chataigner, Marc, Cousin, Areski, Crépey, Stéphane, Dixon, Matthew, and Gueye, Djibril

Subjects
Quantitative Finance - Mathematical Finance, Quantitative Finance - Computational Finance, Statistics - Machine Learning
Abstract

We explore the abilities of two machine learning approaches for no-arbitrage interpolation of European vanilla option prices, which jointly yield the corresponding local volatility surface: a finite dimensional Gaussian process (GP) regression approach under no-arbitrage constraints based on prices, and a neural net (NN) approach with penalization of arbitrages based on implied volatilities. We demonstrate the performance of these approaches relative to the SSVI industry standard. The GP approach is proven arbitrage-free, whereas arbitrages are only penalized under the SSVI and NN approaches. The GP approach obtains the best out-of-sample calibration error and provides uncertainty quantification.The NN approach yields a smoother local volatility and a better backtesting performance, as its training criterion incorporates a local volatility regularization term.

Published
2022

39. Organic Structures Emerging From Bio-Inspired Graph-Rewriting Automata

Author

Cousin, Paul and Maignan, Aude

Subjects
Mathematics - Dynamical Systems
Abstract

Graph-Rewriting Automata (GRA) are an extension of Cellular Automata to a dynamic structure using local graph-rewriting rules. This work introduces linear algebra based tools that allow for a practical investigation of their behavior in deeply extended time scales. A natural subset of GRA is explored in different ways thereby demonstrating the benefits of this method. Some elements of the subset were discovered to create chaotic patterns of growth and others to generate organic-looking graph structures. These phenomena suggest a strong relevance of GRA in the modeling natural complex systems. The approach presented here can be easily adapted to a wide range of GRA beyond the chosen subset.

Published
2022
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40. Biomarker-directed targeted therapy plus durvalumab in advanced non-small-cell lung cancer: a phase 2 umbrella trial

Author

Besse, Benjamin, Pons-Tostivint, Elvire, Park, Keunchil, Hartl, Sylvia, Forde, Patrick M., Hochmair, Maximilian J., Awad, Mark M., Thomas, Michael, Goss, Glenwood, Wheatley-Price, Paul, Shepherd, Frances A., Florescu, Marie, Cheema, Parneet, Chu, Quincy S. C., Kim, Sang-We, Morgensztern, Daniel, Johnson, Melissa L., Cousin, Sophie, Kim, Dong-Wan, Moskovitz, Mor T., Vicente, David, Aronson, Boaz, Hobson, Rosalind, Ambrose, Helen J., Khosla, Sajan, Reddy, Avinash, Russell, Deanna L., Keddar, Mohamed Reda, Conway, James P., Barrett, J. Carl, Dean, Emma, Kumar, Rakesh, Dressman, Marlene, Jewsbury, Philip J., Iyer, Sonia, Barry, Simon T., Cosaert, Jan, and Heymach, John V.

Published
2024
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41. Multicentric development and evaluation of [18F]FDG PET/CT and CT radiomic models to predict regional and/or distant recurrence in early-stage non-small cell lung cancer treated by stereotactic body radiation therapy

Author

Lucia, François, Louis, Thomas, Cousin, François, Bourbonne, Vincent, Visvikis, Dimitris, Mievis, Carole, Jansen, Nicolas, Duysinx, Bernard, Le Pennec, Romain, Nebbache, Malik, Rehn, Martin, Hamya, Mohamed, Geier, Margaux, Salaun, Pierre-Yves, Schick, Ulrike, Hatt, Mathieu, Coucke, Philippe, Hustinx, Roland, and Lovinfosse, Pierre

Published
2024
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44. The role of electron polarization on nuclear spin diffusion

Author

Chessari, Alessandro, Cousin, Samuel F., Jannin, Sami, and Stern, Quentin

Subjects
Condensed Matter - Other Condensed Matter, Nuclear Theory
Abstract

Dynamic nuclear polarization (DNP) is capable of boosting signals in nuclear magnetic resonance by orders of magnitude by creating out-of-equilibrium nuclear spin polarization. The diffusion of nuclear spin polarization in the vicinity of paramagnetic dopants is a crucial step for DNP and remains yet not well understood. In this Letter, we show that the polarization of the electron spin controls the rate of proton spin diffusion in a DNP sample at 1.2 K and 7 T; at increasingly high electron polarization, spin diffusion vanishes. We rationalize our results using a 2 nucleus - 1 electron model and Lindblad s Master equation, which generalizes preexisting models in the literature and qualitatively accounts for the experimental observed spin diffusion dynamics., Comment: Main text: 6 pages, 3 figures Supplement: 9 pages, 4 figures

Published
2022
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45. Properties of the Nili Fossae Olivine-clay-carbonate lithology: orbital and in situ at S\'e\'itah

Author

Brown, Adrian J., Kah, Linda, Mandon, Lucia, Wiens, Roger, Pinet, Patrick, Clavé, Elise, Mouélic, Stéphane Le, Udry, Arya, Gasda, Patrick J., Royer, Clément, Hickman-Lewis11, Keyron, Cousin, Agnes, Simon, Justin I., Comellas14, Jade, Cloutis, Edward, Fouchet, Thierry, Fairén, Alberto G., Connell, Stephanie, Flannery, David, Horgan, Briony, Mayhew, Lisa, Treiman, Allan, Núñez, Jorge I., Wogsland, Brittan, Benzerara, Karim, Amundsen, Hans E. F., Quantin-Nataf, Cathy, Hand, Kevin P., Debaille, Vinciane, Essunfeld, Ari, Beck, Pierre, Tosca, Nicholas J., Madariaga, Juan M., and Ravanis, Eleni

Subjects
Astrophysics - Earth and Planetary Astrophysics, Physics - Geophysics
Abstract

We examine the observed properties of the Nili Fossae olivine-clay-carbonate lithology from orbital data and in situ by the Mars 2020 rover at the S\'e\'itah unit in Jezero crater, including: 1) composition (Liu, 2022) 2) grain size (Tice, 2022) 3) inferred viscosity (calculated based on geochemistry collected by SuperCam (Wiens, 2022)). Based on the low viscosity and distribution of the unit we postulate a flood lava origin for the olivine-clay-carbonate at S\'e\'itah. We include a new CRISM map of the clay 2.38 {\mu}m band and use in situ data to show that the clay in the olivine cumulate in the S\'e\'itah formation is consistent with talc or serpentine from Mars 2020 SuperCam LIBS and VISIR and MastCam-Z observations. We discuss two intertwining aspects of the history of the lithology: 1) the emplacement and properties of the cumulate layer within a lava lake, based on terrestrial analogs in the Pilbara, Western Australia, and using previously published models of flood lavas and lava lakes, and 2) the limited extent of post emplacement alteration, including clay and carbonate alteration (Clave, 2022; Mandon, 2022)., Comment: 34 pages, 15 figures

Published
2022

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