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Géorgios Deligiannakis, A Cultural History of Late Roman Cyprus (Cyprus Research Center. Texts and Studies in the History of Cyprus 90). – Lithographica, Leukôsia 2022. 29 × 20 ; relié. 194 p., 42 fig. couleurs et noir et blanc. ISBN 978-9963-0-8169-1.
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Concurrent oxygen evolution reaction pathways revealed by high-speed compressive Raman imaging
No full text23 pages, 5 figuresInternational audienceTransition metal oxides are state-of-the-art materials for catalysing the oxygen evolution reaction (OER), whose slow kinetics currently limit the efficiency of water electrolysis. However, microscale physicochemical heterogeneity between particles, dynamic reactions both in the bulk and at the surface, and an interplay between particle reactivity and electrolyte makes probing the OER challenging. Here, we overcome these limitations by applying state-of-the-art compressive Raman imaging to uncover competing bias-dependent mechanisms for the OER in a solid electrocatalyst, {\alpha}-Li2IrO3. By spatially and temporally tracking changes in the in- and out-of-plane Ir-O stretching modes - identified by density functional theory calculations - we follow catalytic activation and charge accumulation following ion exchange under a variety of electrolytes, particle compositions and cycling conditions. We extract velocities of phase fronts and demonstrate that at low overpotentials oxygen is evolved by the combination of an electrochemical-chemical mechanism and a classical electrocatalytic adsorbate mechanism, whereas at high overpotentials only the latter occurs. These results provide strategies to promote mechanisms for enhanced OER performances, and highlight the power of compressive Raman imaging for low-cost, chemically specific tracking of microscale reaction dynamics in a broad range of systems where ion and electron exchange can be coupled to structural changes, i.e. catalysts, battery materials, memristors, etc
Quantum Mpemba Effect in Random Circuits
No full textInternational audienceThe essence of the Mpemba effect is that non-equilibrium systems may relax faster the further they are from their equilibrium configuration. In the quantum realm, this phenomenon arises in the dynamics of closed systems, where it is witnessed by fundamental features such as symmetry and entanglement. Here, we study the quantum Mpemba effect in charge-preserving random circuits on qudits via entanglement asymmetry, combining extensive numerical simulations and analytical mapping to a classical statistical mechanics problem. We show that the more asymmetric certain classes of initial states (tilted ferromagnets) are, the faster they restore symmetry and reach the grand-canonical ensemble. Conversely, other classes of states (tilted antiferromagnets) do not show the Mpemba effect. Our analysis is based on minimal principles -- locality, unitarity, and symmetry. Consequently, our results represent a significant advancement in clarifying the emergence of Mpemba physics in generic systems, including Hamiltonian and Floquet quantum circuits
Long range mutual activation establishes Rho and Rac polarity during cell migration
No full textIn migrating cells, the GTPase Rac organizes a protrusive front, whereas Rho organizes a contractile back. How these GTPases are appropriately positioned at the opposite poles of a migrating cell is unknown. Here we leverage optogenetics, manipulation of cell mechanics, and mathematical modeling to reveal a surprising long-range mutual activation of the front and back polarity programs that complements their well-known local mutual inhibition. This long-range activation is rooted in two distinct modes of mechanochemical crosstalk. Local Rac-based protrusion stimulates Rho activation at the opposite side of the cell via membrane tension-based activation of mTORC2. Conversely, local Rho-based contraction induces cortical-flow-based remodeling of membrane-to-cortex interactions leading to PIP2 release, PIP3 generation, and Rac activation at the opposite side of the cell. We develop a minimal unifying mechanochemical model of the cell to explain how this long-range mechanical facilitation complements local biochemical inhibition to enable robust global Rho and Rac partitioning. Finally, we validate the importance of this long-range facilitation in the context of chemoattractant-based cell polarization and migration in primary human lymphocytes. Our findings demonstrate that the actin cortex and plasma membrane function as an integrated mechanochemical system for long-range partitioning of Rac and Rho during cell migration and likely other cellular contexts
How did food and foodways spread during the Neolithisation of the northwestern Mediterranean?
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Two Sets of Letters from Tell Harmal Addressed by the Ruler of Ešnunna to Samsi-Addu
No full textInternational audienceThe present article is devoted to two tablets discovered at Tell Harmal, the ancient Šaduppum, in 1945 and 1948. It offers a re-edition of IM 54005 and the publication of the previously unpublished IM 51881. IM 51881 is a letter addressed to Samsi-Addu, a duplicate of the second letter from the Prince (rubûm) of Ešnunna contained in IM 54005, which completes its text and enables us to understand it better. A study of the geographical and historical context brings to light hitherto unknown elements, such as a place called Šinam (different from Šinamum), or the role of King Yakun-Derim of Huršitum. The events mentioned predate Samsi-Addu's conquest of Mari, when he was still subordinate to the king of Ešnunna (Ipiq-Adad II or Naram-Sin). The two tablets, partly duplicates, contain many obscure passages, and not only because of their state of preservation; they are clearly school exercises. This shows that copying “historical letters” in Akkadian was part of the scribes' training and suggests that these copies reflect authentic texts.Le présent article est consacré à deux tablettes découvertes à Tell Harmal, l'antique Šaduppum, en 1945 et 1948. Il offre une réédition de IM 54005 et la publication de l'inédit IM 51881. Ce dernier est une lettre adressée à Samsi-Addu ; il s'agit d'un duplicat de la seconde lettre du Prince (rubûm) d'Ešnunna contenue dans IM 54005, qui complète son texte et permet de mieux le comprendre. Une étude du contexte géographique et historique met en lumière des éléments inconnus jusqu'alors, comme un lieu nommé Šinam (différent de Šinamum), ou le rôle du roi Yakun-Derim de Huršitum. Les événements mentionnés datent d'une époque antérieure à la conquête de Mari par Samsi-Addu, lorsqu'il était encore subordonné au roi d'Ešnunna (Ipiq-Adad II ou Naram-Sin). Les deux tablettes, en partie duplicats, comportent de nombreux passages obscurs, et pas seulement du fait de leur état de conservation ; il s'agit manifestement d'exercices scolaires. Cela montre que la copie de « lettres historiques » en akkadien faisait partie de la formation des scribes et suggère que ces copies reflètent des textes authentiques
Comptabilité et administration : le cas de la gestion de la viande dans le palais de Mari
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Archéologie, patrimoine et archives, Les fouilles anciennes à Ras Shamra et à Minet el-Beida, III
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“Dreaming to sing: learning and dream creation in the Australian desert”
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