Tournesol: Permissionless Collaborative Algorithmic Governance with Security Guarantees

Recommendation algorithms play an increasingly central role in our societies. However, thus far, these algorithms are mostly designed and parameterized unilaterally by private groups or governmental authorities. In this paper, we present an end-to-end permissionless collaborative algorithmic governance method with security guarantees. Our proposed method is deployed as part of an open-source content recommendation platform https://tournesol.app, whose recommender is collaboratively parameterized by a community of (non-technical) contributors. This algorithmic governance is achieved through three main steps. First, the platform contains a mechanism to assign voting rights to the contributors. Second, the platform uses a comparison-based model to evaluate the individual preferences of contributors. Third, the platform aggregates the judgements of all contributors into collective scores for content recommendations. We stress that the first and third steps are vulnerable to attacks from malicious contributors. To guarantee the resilience against fake accounts, the first step combines email authentication, a vouching mechanism, a novel variant of the reputation-based EigenTrust algorithm and an adaptive voting rights assignment for alternatives that are scored by too many untrusted accounts. To provide resilience against malicious authenticated contributors, we adapt Mehestan, an algorithm previously proposed for robust sparse voting. We believe that these algorithms provide an appealing foundation for a collaborative, effective, scalable, fair, contributor-friendly, interpretable and secure governance. We conclude by highlighting key challenges to make our solution applicable to larger-scale settings.Comment: 31 pages, 5 figure

Highly cohesive dual nanoassemblies for complementary multiscale bioimaging

International audienceInnovative nanostructures made of a high payload of fluorophores and superparamagnetic nanoparticles (NPs) have simply been fabricated upon self-assembling in a two-step process. The resulting hybrid supraparticles displayed a dense shell of iron oxide nanoparticles tightly attached through an appropriate polyelectrolyte to a highly emissive non-doped nanocore made of more than 10 5 small organic molecules. Cooperative magnetic dipole interactions arose due to the closely packed magnetic NPs at the nanoarchitecture surface, causing enhanced NMR transverse relaxivity. Large in vivo MRI T 2 contrast was thus obtained with unusually diluted solutions after intravenous injection in small rodents. Two-photon excited fluorescence imaging could be performed, achieving unprecedented location resolution for agents combining both magnetic nanoparticles and fluorescence properties. Finally, TEM imaging of the sectioned mouse tissue succeeded in isolating the core–shell structures, which represents the first image of intact complex magnetic and fluorescent nanoassemblies upon in vivo injection. Such highly cohesive dual nanoarchitectures should open great horizons toward the assessment with high spatial resolution of the drug or labeled stem cell biodistribution

Bluetooth Low Energy throughput in densely deployed radio environment

International audienceBluetooth Low Energy (BLE) is a promising 2.4 GHz technology for Body Area Networks (BAN) in health care and lifestyle applications. However, the global increase of wireless devices using the crowded spectrum in the 2.4 GHz frequency band can create coexistence issues. This work studies the performance of BLE in environments with multiple BLE devices. An experimental setup consisting of 10 BLE nodes is used to measure BLE application throughput with different connection parameters and under different interference sources, such as other BLE devices and WiFi. The results quantify the decrease of the application throughput and the influence of BLE connection parameters in the experimental settings, as well as suggest parameter values suitable for densely deployed environments

Photoactive chelating organic nanospheres as central platforms of bimodal hybrid nanoparticles

International audienceAn innovative approach based on the combination of pre-formed nano-objects using photoactive chelating organic nano-platforms has been developed to elaborate hybrid functional nanoparticles. In this way, original “raspberry-like” structures made of a self-assembled fluorescent organic core surrounded by magnetic nanoparticles have been obtained. The resulting fluo@mag architecture exhibits strong brilliance and magnetization compared to the usual structures made of an inorganic core. The reported fabrication procedure represents a simple and very general method which can be applied to any couple of units displaying complementary complexing abilities to yield dense magneto- and photoactive nanomaterials whose core emission appears advantageously insensitive to the surroundings

Tuning the architectural integrity of high-performance magneto-fluorescent core-shell nanoassemblies in cancer cells

International audienceHigh-density nanoarchitectures, endowed with simultaneous fluorescence and contrast properties for MRI and TEM imaging, have been obtained using a simple self-assembling strategy based on supramolec- ular interactions between non-doped fluorescent organic nanoparticles (FON) and superparamagnetic nanoparticles. In this way, a high-payload core-shell structure FON@mag has been obtained, protecting the hydrophobic fluorophores from the surroundings as well as from emission quenching by the shell of magnetic nanoparticles. Compared to isolated nanoparticles, maghemite nanoparticles self-assembled as an external shell create large inhomogeneous magnetic field, which causes enhanced transverse relaxivity and exacerbated MRI contrast. The magnetic load of the resulting nanoassemblies is evaluated using magnetic sedimentation and more originally electrospray mass spectrometry. The role of the stabilizing agents (citrate versus polyacrylate anions) revealed to be crucial regarding the cohesion of the resulting high-performance magneto-fluorescent nanoassemblies, which questions their use after cell internalization as nanocarriers or imaging agents for reliable correlative light and electron microcopy

A networked wearable device for chemical multisensing

International audienceThe low-power sensing platform proposed by the Convergence project is foreseen as a wireless, low-power and multifunctional wearable system empowered by energy-efficient technologies. This will allow meeting the strict demands of life-style and healthcare applications in terms of autonomy for quasi-continuous collection of data for early-detection strategies. The system is compatible with different kinds of sensors, able to monitor not only health indicators of individual person (physical activity, core body temperature and biomarkers) but also the environment with chemical composition of the ambient air (NOx, COx, NHx particles) returning meaningful information on his/her exposure to dangerous (safety) or pollutant agents. In this article, we introduce the specifications and the design of the low-power sensing platform and the different sensors developed in the project, with a particular focus on pollutant sensing capabilities and specifically on NO2 sensor based on graphene and CO sensor based on polyaniline ink

Sensors platform for health and environmental monitoring

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Wearable Smart Sensing platform for environmental and health monitoring: the Convergence project

International audienceThe low-power sensing platform proposed by the Convergence project is foreseen as a wireless, low-power and multifunctional wearable system empowered by energy-efficient technologies. This will allow meeting the strict demands of life-style and healthcare applications in terms of autonomy for quasi-continuous collection of data for early-detection strategies. The system is compatible with different kinds of sensors, able to monitor not only health indicators of individual person (physical activity, core body temperature and biomarkers) but also the environment with chemical composition of the ambient air (NOx, COx, NHx particles) returning meaningful information on his/her exposure to dangerous (safety) or pollutant agents. In this article, we introduce the specifications and the design of the low-power sensing platform and the different sensors developed in the project, with a particular focus on pollutant sensing capabilities and specifically on NO2 sensor based on graphene and CO sensor based on polyaniline ink