High performance underwater UHF radio antenna development

International audienceThis study presents the development of a UHF radioantenna for underwater transmissions in order to rapidly transmit large size files and real-time video

Private governance in royalty collection: Effectiveness and limitations in tracing GM soybean in Brazil

Ce papier analyse l'émergence d'une innovation institutionnelle en accompagnement de la diffusion du soja génétiquement modifié au Brésil. Il en découle une gouvernance plutôt efficace par la création d'une situation gagnant-gagnant pour les acteurs impliqués, au moins à court terme, tant que la coexistence avec les variétés conventionnelles peut demeurer. Cette coexistence est menacée surtout du fait d'une absence de prime de marché pour le soja conventionnel.OGM; soja; Brésil; innovation institutionnelle; redevance d'emploi; coexistence

The curse of language biases in remote sensing VQA: the role of spatial attributes, language diversity, and the need for clear evaluation

Remote sensing visual question answering (RSVQA) opens new opportunities for the use of overhead imagery by the general public, by enabling human-machine interaction with natural language. Building on the recent advances in natural language processing and computer vision, the goal of RSVQA is to answer a question formulated in natural language about a remote sensing image. Language understanding is essential to the success of the task, but has not yet been thoroughly examined in RSVQA. In particular, the problem of language biases is often overlooked in the remote sensing community, which can impact model robustness and lead to wrong conclusions about the performances of the model. Thus, the present work aims at highlighting the problem of language biases in RSVQA with a threefold analysis strategy: visual blind models, adversarial testing and dataset analysis. This analysis focuses both on model and data. Moreover, we motivate the use of more informative and complementary evaluation metrics sensitive to the issue. The gravity of language biases in RSVQA is then exposed for all of these methods with the training of models discarding the image data and the manipulation of the visual input during inference. Finally, a detailed analysis of question-answer distribution demonstrates the root of the problem in the data itself. Thanks to this analytical study, we observed that biases in remote sensing are more severe than in standard VQA, likely due to the specifics of existing remote sensing datasets for the task, e.g. geographical similarities and sparsity, as well as a simpler vocabulary and question generation strategies. While new, improved and less-biased datasets appear as a necessity for the development of the promising field of RSVQA, we demonstrate that more informed, relative evaluation metrics remain much needed to transparently communicate results of future RSVQA methods

Dark halo baryons not in ancient halo white dwarfs

Having ruled out the possibility that stellar objects are the main contributor of the dark matter embedding galaxies, microlensing experiments cannot exclude the hypothesis that a significant fraction of the Milky Way dark halo might be made of MACHOs with masses in the range 0.5-0.8 \msun. Ancient white dwarfs are generally considered the most plausible candidates for such MACHOs. We report the results of a search for such white dwarfs in a proper motion survey covering a 0.16 sqd field at three epochs at high galactic latitude, and 0.938 sqd at two epochs at intermediate galactic latitude (VIRMOS survey), using the CFH telescope. Both surveys are complete to I = 23, with detection efficiency fading to 0 at I = 24.2. Proper motion data are suitable to separate unambiguously halo white dwarfs identified by belonging to a non rotating system. No candidates were found within the colour-magnitude-proper motion volume where such objects can be safely discriminated from any standard population as well as from possible artefacts. In the same volume, we estimate the maximum white dwarf halo fraction compatible with this observation at different significance levels if the halo is at least 14 gigayears old and under different ad hoc initial mass functions. Our data alone rules out a halo fraction greater than 14% at 95% confidence level. Combined with two previous investigations exploring comparable volumes pushes the limit below 4 % (95% confidence level) or below 1.3% (64% confidence), this implies that if baryonic dark matter is present in galaxy halos, it is not, or it is only marginally in the form of faint hydrogen white dwarfs.Comment: accepted in Astronomy and Astrophysics (19-05-2004

Enabling discovery of solar system objects in large alert data streams

With the advent of large-scale astronomical surveys such as the Zwicky Transient Facility (ZTF), the number of alerts generated by transient, variable and moving astronomical objects is growing rapidly, reaching millions per night. Concerning solar system minor planets, their identification requires linking the alerts of many observations over a potentially large time, leading to a very large combinatorial number. This work aims to identify new candidates for solar system objects from massive alert data streams produced by large-scale surveys, such as the ZTF and the Vera C. Rubin Observatory's Legacy Survey of Space and Time. Our analysis used the Fink alert broker capabilities to reduce the 111,275,131 processed alerts from ZTF between November 2019 and December 2022 to only 389,530 new solar system alert candidates over the same period. We then implemented a linking algorithm, Fink-FAT, to create real-time trajectory candidates from alert data and extract orbital parameters. The analysis was validated on ZTF alert packets linked to confirmed solar system objects from the Minor Planet Center database. Finally, the results were confronted against follow-up observations. Between November 2019 and December 2022, Fink-FAT extracted 327 new orbits from solar system object candidates at the time of the observations, over which 65 were still unreported in the MPC database as of March 2023. After two late follow-up observation campaigns of six orbit candidates, four were associated with known solar system minor planets, and two remain unknown. Fink-FAT is deployed in the Fink broker and successfully analyzes in real time the alert data from the ZTF survey by regularly extracting new candidates for solar system objects. Our scalability tests also show that Fink-FAT can handle the even larger volume of alert data that the Rubin Observatory will send.Comment: submitted to A&

Bayesian estimation of a 1D hydrodynamic model in a tidal river: Application to the Lower Seine River, France

Monitoring water stage and discharge at hydrometric stations is essential for flood characterization and prediction. Continuous measurement is feasible for stage records, whereas discharge must be calculated, typically using a rating curve. Several methods have been developed, such as surface velocity measurement or rating curve methods. Nevertheless, hydrometric stations may be influenced by tidal fluctuations, leading to transient flow conditions that can disrupt the stage-discharge relation, complicating the accurate estimation of discharge. In the case of a quasi-unsteady flow, the dynamic can be managed by a relationship between water level, elevation, and discharge based on the Manning-Strickler formula and measurements of water level and slope of the waterline. However, in unsteady flow, when tidal effects are pronounced, these types of relationships and their variations have proven to be less effective. To capture the complex flow dynamics, including flow reversal, an approach via a 1D hydrodynamic model is proposed. Here, model estimation refers to estimating the posterior distribution of parameters and the structural error model.To set up the model, the cross-sectional geometry, friction coefficient, upstream discharge(s), and downstream water level are necessary. In hydrodynamic modeling, the friction coefficients, often represented through a set of Strickler coefficients, are the main calibration parameter, but manual calibration is difficult due to spatial variations in roughness combined with unsteady flow. Furthermore, understanding and quantifying uncertainties associated with data and the model are an important step in the calibration process. Therefore, automatic calibration of friction coefficients is proposed through Bayesian inference.In terms of numerical tools, the 1D hydrodynamic code used here is Mage, developed by INRAE, which solves the 1D Saint-Venant equations for river flows and transients. However, the proposed method is not specific to a given simulation code: it can be applied to any usual 1D hydrodynamic code. Bayesian calibration is performed using the software BaM! (Bayesian modeling: https://github.com/BaM-tools), which allows specifying prior information on model parameters (in this case, friction coefficients) to then estimate them with associated uncertainties, using observations themselves with their uncertainties (not only water levels but also gauging campaigns).Comment: in French language, Colloque SHF "Pr{\'e}vision des crues et des inondations -- Avanc{\'e}es, valorisation et perspectives'', Soci{\'e}t{\'e} Hydrotechnique de France (SHF), Nov 2023, Toulouse, Franc

The Na+/Ca2+, K+ exchanger NCKX4 is required for efficient cone-mediated vision

Calcium (Ca2+) plays an important role in the function and health of neurons. In vertebrate cone photoreceptors, Ca2+ controls photoresponse sensitivity, kinetics, and light adaptation. Despite the critical role of Ca2+ in supporting the function and survival of cones, the mechanism for its extrusion from cone outer segments is not well understood. Here, we show that the Na+/Ca2+, K+ exchanger NCKX4 is expressed in zebrafish, mouse, and primate cones. Functional analysis of NCKX4-deficient mouse cones revealed that this exchanger is essential for the wide operating range and high temporal resolution of cone-mediated vision. We show that NCKX4 shapes the cone photoresponse together with the cone-specific NCKX2: NCKX4 acts early to limit response amplitude, while NCKX2 acts late to further accelerate response recovery. The regulation of Ca2+ by NCKX4 in cones is a novel mechanism that supports their ability to function as daytime photoreceptors and promotes their survival

Bioengineered lungs generated from human iPSCs‐derived epithelial cells on native extracellular matrix

The development of an alternative source for donor lungs would change the paradigm of lung transplantation. Recent studies have demonstrated the potential feasibility of using decellularized lungs as scaffolds for lung tissue regeneration and subsequent implantation. However, finding a reliable cell source and the ability to scale up for recellularization of the lung scaffold still remain significant challenges. To explore the possibility of regeneration of human lung tissue from stem cells in vitro, populations of lung progenitor cells were generated from human iPSCs. To explore the feasibility of producing engineered lungs from stem cells, we repopulated decellularized human lung and rat lungs with iPSC‐derived epithelial progenitor cells. The iPSCs‐derived epithelial progenitor cells lined the decellularized human lung and expressed most of the epithelial markers when were cultured in a lung bioreactor system. In decellularized rat lungs, these human‐derived cells attach and proliferate in a manner similar to what was observed in the decellularized human lung. Our results suggest that repopulation of lung matrix with iPSC‐derived lung epithelial cells may be a viable strategy for human lung regeneration and represents an important early step toward translation of this technology.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142929/1/term2589.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142929/2/term2589_am.pd