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Biophysics of organoids
No full textInternational audienceOrganoids, 3D in vitro structures derived from embryonic or adult stem cells, offer powerful models for studying tissue patterning, development, morphogenesis, organ physiology and disease. These systems replicate biological processes, such as cell differentiation, symmetry breaking, and tissue organization, while revealing species-specific developmental variations. Biophysical factors, such as extracellular matrix composition, fluid dynamics, and tissue stiffness, interact with biochemical signals to drive organoid formation, revealing a complex multiscale phenomenon during growth, patterning and homeostasis. Physics-based approaches provide a framework to understand these processes from first principles. In recent years, a growing community of researchers has been exploring what can be termed the "biophysics of organoids." This review covers a broad range of approaches-mechanical, kinetic, information-based, statistical, and AI-driven-to study organoid development, offering insights into organogenesis, disease modeling, and regenerative medicine
Lifting a CSS code via its handlebody realization
No full textWe present a topological approach to lifting a quantum CSS code. In previous work, we proposed lifting a CSS code by constructing covering spaces over its 2D simplicial complex representation, known as the Tanner cone-complex. This idea was inspired by the work of Freedman and Hastings, which associates CSS codes with handlebodies. In this paper, we show how the handlebody realization of a code can also be used to perform code lifting, and we provide a more detailed discussion of why this is essentially equivalent to the Tanner cone-complex approach. As an application, we classify lifts of hypergraph-product codes via their handlebody realization
Hölder type estimates for Gaussian multiplicative chaos
No full textWe investigate the right tail behavior of a certain class of GMC ratios, reminiscent of Hölder's inequality. We start with a heuristic argument to justify the optimal exponent in the tail estimate. Since Kahane's convexity inequality does not apply to GMC ratios, implementing the heuristic in the continuous setting is nontrivial from the viewpoint of GMC theory. We address the problem by enlarging the class of GMC ratios considered, and deduce the upper and lower bounds for the right tail of GMC ratios
The Domain Adaptation problem in photometric redshift estimation: a solution applied to the HSC Survey
No full textInternational audienceThe multi-band HSC-CLAUDS survey comprises several sky regions with varying observing conditions, only one of which, the COSMOS Ultra Deep Field (UDF), offers extensive redshift coverage. We aim to exploit a complete sample of labeled galaxies from the COSMOS UDF at i<25 (z<~5) to train a convolutional neural network (CNN) and infer more accurate photometric redshifts in the other regions than those currently available from SED-fitting methods. To address the severe domain mismatch problem we observed when applying the trained CNN to regions other than the COSMOS UDF, we developed an unsupervised adversarial domain adaptation network that we grafted onto the CNN. The method is validated by three tests: the predicted redshifts are compared to the spectroscopic redshifts that are available for limited samples of mostly bright galaxies; the predicted redshift distributions of the entire galaxy population of a given field in several intervals of magnitude are compared to those of the COSMOS UDF, assumed to be representative; the redshifts predicted for a sample of galaxies selected by narrow-band filter observations sensitive to [OII] emitters at z~1.47 are compared to those of confirmed [OII] emission line galaxies. The results show successful domain adaptation: the network is able to transfer its redshift classification capability learnt from the COSMOS UDF to other regions of HSC-CLAUDS. Accuracy varies depending on magnitude and redshift, following that of the labels we used, but far exceeds that of currently available photometric redshifts. The catalogs of CNN redshifts we inferred for the XMM, DEEP2 and ELAIS fields and for the remaining COSMOS region (~4 million sources in total at i<25) are made public
Parcours balkaniques, trajectoires cartographiques : des cartes à hauteur d’individus
No full textNational audienceThis contribution offers a critical reflection on the mapping of migratory routes, at a time when the most widely circulated maps contribute to the dehumanisation of migrants. It argues in favour of a cartographic approach 'at the level of individuals', understood as a relational process that assumes a subjective approach, by comparing two experiments with migrants in the Balkans. The singular journeys of Simon and Ahmed provide an insight into the phenomenon of the externalisation of European migration policies in the Balkan region, constructed as a channelling and filtering airlock from the 2000s onwards. In the vein of radical, sensitive and participatory epistemologies, the making of the two maps is deconstructed to bring out the intentionality and imprint of the cartographers, which are often obscured in cartographic production. The attention paid to encounters, interactions, gestures and temporalities highlights the cartographic trajectories forged between the cartographer and the protagonists of the journeys, in order to place the map at the centre of an approach to re-humanising migration, as a potential means of action and/or of setting cartographers in motion.Cette contribution propose une réflexion critique sur la cartographie des parcours migratoires, à l’heure où les cartes les plus diffusées concourent à la déshumanisation des personnes en migration. La démonstration plaide pour une démarche cartographique « à hauteur d’individus », entendue comme un processus relationnel assumant une démarche subjective, en mettant en regard deux expérimentations avec des personnes en migration dans les Balkans. Les parcours singuliers de Simon et Ahmed instruisent le phénomène d’externalisation des politiques migratoires européennes dans l’espace balkanique, construit comme un sas canalisant et filtrant dès les années 2000. Dans la veine des épistémologies radicales, sensibles et participatives, la fabrique des deux cartes est déconstruite pour faire émerger l’intentionnalité et l’empreinte des cartographes, souvent occultées dans les productions cartographiques. L’attention accordée aux rencontres, interactions, gestes et temporalités met en évidence les trajectoires cartographiques nouées entre la cartographe et les protagonistes des parcours, pour envisager la carte au centre d’une démarche de ré-humanisation des migrations, comme potentiel moyen d’action et/ou de mise en mouvement des cartographes
Language and Screen-Based Multimodal Communication
No full textCollection online "Social Sciences"The main objective of this article is to explore how language and languaging are impacted by the mediatization of digital technologies. First we point to the main characteristics of screen-based communication, that is multimodality, interactivity, mobility, relationship to time and technogenres. Then we address three current research issues: multilingualism and translations, discrimination and hate speech, and automatic processing of languages in large language models
Possible Explanation of at Large Using Quantum Statistical Mechanics
No full textInternational audienceThe ratio of the neutron to proton structure functions, , is expected to approach 1/4 as , based on the assumption that vanishes as . This expectation is in striking disagreement with a recent measurement by the Marathon experiment of the scattering of electrons off the mirror nuclei H and He, showing that is larger than 1/4 for . We have examined the consequences of the Pauli Exclusion Principle for the parton distributions in the nucleon when the partons are described by quantum statistical mechanics. We find that the recent experimental result on the over the broad range of can be well described by the quantum statistical approach
Diplômes des immigrés et des descendants d'immigrés : progrès intergénérationnels et persistance des inégalités
No full textDocument de travailInternational audienceCe document de travail livre des résultats sur les diplômes atteints par les immigré·es et les descendant·es d’immigré·es en fonction de la génération, de l’origine et du genre, à partir de la nouvelle enquête Trajectoires et Origines 2 (INED-INSEE). L’intérêt d’une approche générationnelle dans l’étude des parcours des immigré·es et de leurs descendant·es a été démontré depuis longtemps, notamment aux Etats-Unis (Rumbaut 1997, 2004), mais aussi par les analyses issues de la précédente édition de l’enquête TeO (Beauchemin, Hamel & Simon, 2015). La notion de « génération », telle que nous l’utilisons ici, renvoie à « la distance à la migration, fonction du lieu de naissance de l’individu, de celui de ses deux parents et de son âge d’entrée en France s’il n’y est pas né » (Silberman & Fournier 2006 : 27). Cette perspective, qui insiste sur l’éloignement progressif par rapport à l’évènement migratoire, permet de rendre compte de l’hétérogénéité interne aux immigré·es de différentes origines en termes d’âge à l’arrivée en France, d’une part, et, d’autre part, aux descendant·es d’immigré·es en termes de mixité du couple parental (Myers, Gao & Emeka 2009 ; Kalmijn 2015). Dans ce chapitre, nous distinguons quatre « générations » qui n’ont pas été socialisées en France au même degré : la G1 (individus arrivés adultes en France), la G1.5 (individus arrivés jeunes en France), la G2 (individus nés en France de deux parents immigrés) et la G2.5 (individus nés en France d’un seul parent immigré). Les questions suivantes guident les analyses : un lien plus éloigné à la migration est-il associé à une augmentation du niveau de diplôme ? La structure des diplômes diffère-t-elle selon l’âge à la migration ? Les descendant·es de couples mixtes se rapprochent-ils·elles de la population majoritaire ? Si oui, cela vaut-il pour toutes les origines et quel que soit le genre
Language and screen-based multimodal communication
No full textThe main objective of this chapter is to explore how language and languaging are impacted by the mediatization of digital technologies. First we point to the main characteristics of screen-based communication, that is multimodality, interactivity, mobility, relationship to time and technogenres. Then we address three current research issues: multilingualism and translations, discrimination and hate speech, and automatic processing of languages in large language models.Key points•Screen-based communication has evolved according to the technologies available over time.•Screen-based communication has an impact on language in terms of multimodality, interactivity, mobility, temporal plasticity and new genericity.•The presence of natural languages in screen-based communication provides possibilities and constraints for machine translation.•Screen-based communication has shown issues in interactional dynamics for different types of discrimination and hate speech.•Artificial intelligence and large language models for chatbots in screen-based communication open new insights and research questions in linguistics