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Prospects for the determination of fundamental constants with beyond-state-of-the-art uncertainty using molecular hydrogen ion spectroscopy
No full textInternational audienceThe proton, deuteron and triton masses can be determined relative to the electron mass via rovibrational spectroscopy of molecular hydrogen ions. This has to occur via comparison of the experimentally measured transition frequencies and the ab initio calculated frequencies, whose dependence on the mass ratios can be calculated precisely. In precision experiments to date (on HD and H), the transitions have involved the ground vibrational level and excited vibrational levels with quantum numbers up to . For these transitions, the sensitivity of the ab initio frequency on the high-order-QED contributions is correlated with that on the mass ratios. This prevents an efficient simultaneous determination of these quantities from experimental data, so that the accuracy of the mass ratios is essentially limited by the theoretical uncertainty. Here we analyze how the accuracy of mass ratios may be improved by providing experimental transition frequencies between levels with larger quantum numbers, whose sensitivity on the mass ratio is positive rather than negative, or close to zero. This allows the unknown QED contributions and involved fundamental constants to be much more efficiently determined from a joint analysis of several measurements. We also consider scenarios where transitions of D are included. We find these to be powerful approaches, allowing in principle to reach uncertainties for the mass ratios two orders smaller than CODATA 2018, and without using muonic hydrogen data. For the Rydberg constant and the charge radii, improvements by factors of 4 to 11 are projected
Loss features in ultracold Dy gases: two- versus three-body processes
No full textDipolar gases like erbium and dysprosium have a dense spectrum of resonant loss features associated with their strong anisotropic interaction potential. These resonances display various behaviours with density and temperature, implying diverse microscopic properties. Here, we quantitatively investigate the low-field (B < 6\,\text{G}) loss features in ultracold thermal samples of Dy, revealing two- and three-body dominated loss processes. We investigate their temperature dependence and detect a feature compatible with a -wave Fano-Feshbach resonance, which has not been observed before. We also analyse the expansion of the dipolar Bose-Einstein condensate as a function of the magnetic field and interpret the changes in size close to the resonances with a variation in the scattering length
Extended time frame for restoring inner ear function through gene therapy in Usher1G preclinical model
No full textInternational audienceNeonatal gene therapy has been shown to prevent inner ear dysfunction in mouse models of Usher syndrome type I (USH1), the most common genetic cause of combined deafness-blindness and vestibular dysfunction. However, hearing onset occurs after birth in mice and in utero in humans, making it questionable how to transpose murine gene therapy outcomes to clinical settings. Here, we sought to extend the therapeutic time window in a mouse model for USH1G to periods corresponding to human neonatal stages, more suitable for intervention in patients. Mice with deletion of Ush1g (Ush1g–/–) were subjected to gene therapy after the hearing onset. The rescue of inner ear hair cell structure was evaluated by confocal imaging and electron microscopy. Hearing and vestibular function were assessed by recordings of the auditory brain stem response and vestibulo-ocular reflex and by locomotor tests. Up to P21, gene therapy significantly restored both the hearing and balance deficits in Ush1g–/– mice. However, beyond this age and up to P30, vestibular function was restored but not hearing. Our data show that effective gene therapy is possible in Ush1g–/– mice well beyond neonatal stages, implying that the therapeutic window for USH1G may be wide enough to be transposable to newborn humans
Complexity of Linguistic Structures, Simplicity of Language Mechanisms
No full textInternational audienceFor over sixty years, researchers from across the world have been collaborating in a vast endeavour within what is known as “generative linguistics”, to describe human languages. The founding question of this research is related to the unlimited nature of linguistic possibilities. It has led to the formulation of hypotheses on linguistic combinatorics, its invariant core, and the mechanisms of variation across languages, and to the production of a precise mapping of the structures under study. Although complex, these structures can be reduced to the recursive application of extremely simple mechanisms, which are studied in the Minimalist Programme. This area of research also draws on the illuminating research on language acquisition carried out in an interdisciplinary cognitive science framework
Thoughts on the conception of Nature in Byzantium (11th-12th Centuries)
No full textInternational audienceThis paper examines a new way of looking at nature in Byzantium in the 11th and 12th centuries, and how this may have impacted the conception of the individual. This shift in mentalities is studied by analysing several testimonies from this period, as well as other contemporary elements such as a pronounced taste for gardens and hunting. The study of artworks reinforces this perception, which bears witness to the Byzantines' desire to reflect on their place between nature and Creation.</div
Codification du savoir géographique et particularismes régionaux sous les Tang
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β-Cyclodextrin-NHC-Au(I)-Catalyzed Enantioconvergent 1,5-enyne Cycloisomerizations
No full textInternational audienceEnantioconvergent transformations from racemic mixtures are attractive since they allow to generate optically active products with full conversion despite the possibly adverse kinetic resolution process. When dealing with gold(I)-catalyzed cycloisomerizations, chirality transfer from the precursor is another possible diverting pathway, which renders enantioconvergence challenging. Not surprisingly, enantioconvergent Au(I)-catalyzed processes have re- mained extremely rare. Herein, we show that cavity-driven catalysis using β-Cyclodextrin-NHC-Au(I) complexes bring opportunities to conduct highly enantioconvergent cycloisomerizations of 1,5-enynes, -enynols and –enynyl esters
横田順彌のハチャハチャ小説とその読者
No full textInternational audienceJapanese science fiction was in full swing in the 1970s. It was during this decade that hacha-hacha emerged, with its leading writer, Yokota Jun.ya, and a groundbreaking work, The Great Cosmic Garbage War (1977). This genre, which uses the absurd, pastiche and burlesque, seems to have a single objective: never to take itself seriously and to provoke laughter. Beyond the comic effects the author is seeking, these short texts are part of the development of a certain literary postmodernism that calls into question formats and genres, and questions the status of the author. On the other hand, these texts, strongly rooted in the contemporaneity of their creation, raise the question of their historical destiny and the identity of their readers.La science-fiction japonaise est en pleine effervescence au cours des années 1970. C’est durant cette décennie qu’émerge le hacha-hacha, avec son représentant majeur, Yokota Jun.ya, et une œuvre incontournable, La Grande Guerre cosmique des poubelles (1977). Ce genre qui manie l’absurde, le pastiche, le burlesque ne semble avoir qu’un seul objectif : ne jamais vouloir se prendre au sérieux et provoquer le rire. Au-delà des effets comiques recherchés par l’auteur, ces courts textes participent du développement d’une certaine postmodernité littéraire qui remet en cause les formats, les genres et s’interroge sur le statut de l’auteur. D’autre part, ces textes fortement ancrés dans la contemporanéité de leur création, posent la question de leur destinée historique et de l’identité de leur lectorat.日本のSFが全盛だった1970年代、画期的な作品、「宇宙ゴミ大戦争」を１９７７年世に出した横田順彌を筆頭に、ハチャメチャというジャンルが台頭した。ナンセンス、パスティーシュ、ドタバタを駆使しているこのジャンルは、決して本気にならず、笑いを誘う目的がただひとつあったようである。横田順彌が追及しているコミカルな効果を超えて、これらの短編は、形式やジャンルに疑問を投げかけ、作者の地位を問うなど、文学的ポストモダニズムの発展の一端を担っていると考えられる。その一方で、創作の同時代性に強く根ざしているこれらのテキストは、大衆文学の歴史的運命と読者のアイデンティティという問題を提起している
La tribu comme emblème onomastique… et positionnement politique situé
No full textInternational audienceJacques Berque avait expliqué, dans son fameux article "Qu'est-ce qu'une tribu nord-Africaine", la tendance qu'il observait dans le processus de formation de cette entité sociopolitique : "la plupart des tribus agrègent des éléments venus de tous les horizons, et, en tout cas, venus 'd'ailleurs'. Cette contradiction entre la personnalité collective et l'origine des cellules qui la composent est véritablement une loi du genre" 1. Rompant avec les paradigmes dominants, Jacques Berque, ainsi que Pierre Bourdieu dans son sillage 2 , furent parmi les premiers à rejeter l'explication par la généalogie pour s'accorder sur l'importance du nom comme référent identitaire. Seules les familles et les fractions constitueraient les vrais groupes de parenté 3 ; la tribu ne serait, quant à elle, qu'une alliance contractuelle autour d'un nom : un emblème onomastique. Ibn Khaldûn, quelques siècles plus tôt, avait déjà attiré l'attention sur le caractère fictif des généalogies et sur le rôle fondamental des liens de l'utérus, des liens cognatiques (silat ararhâm), dans la formation des tribus 4. La formule de Jacques Berque vient conforter l'idée que la tribu est avant tout une organisation socio-politique basée sur des processus d'alliance, de protection et de contrat, davantage que sur les logiques généalogiques mises classiquement en avant (et qui demeurent importantes dans les représentations locales). Elle ajoute cependant un élément important : l'importance du nom, du référent onomastique, dans les représentations affichées de la tribu. Pierre Bourdieu avait par ailleurs tenté d'expliquer le rôle du nom, de cet 'emblème onomastique' dans le cadre de la logique de l'honneur et du prestige telle qu'elle se conçoit en Afrique du Nord
Density and current statistics in boundary-driven monitored fermionic chains
No full textInternational audienceWe consider a one-dimensional system of non-interacting fermions featuring both boundary driving and continuous monitoring of the bulk particle density. Due to the measurements, the expectation values of the local density and current operators are random variables whose average behavior is described by a well studied Lindblad master equation. By means of exact numerical computations, we go beyond the averaged dynamics and study their full probability distribution functions, focusing on the late-time stationary regime. We find that, contrary to the averaged values, the spatial profiles of the median density and current are non-trivial, exhibiting qualitative differences as a function of the monitoring strength. At weak monitoring, the medians are close to the means, displaying diffusive spatial profiles. At strong monitoring, we find that the median density and current develop a domain-wall and single-peak profile, respectively, which are suggestive of a Zeno-like localization in typical quantum trajectories. While we are not able to identify a sharp phase transition as a function of the monitoring rate, our work highlights the usefulness of characterizing typical behavior beyond the averaged values in the context of monitored many-body quantum dynamics