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Formulation de mélanges PET/PE dans la perspective de leur recyclage par impression 3D
No full textInternational audienceThe amount of plastic waste has become a serious challenge on a global scale. Despite the technical and legislative developments in favor of plastic packaging recycling, multilayered packaging (such as poly(ethylene terephthalate) (PET) and polyethylene (PE)) is still difficult to recycle by direct mechanical recycling. One of the possible solutions consists in revalorizing these non-recycled plastic waste streams short circuits using 3D printing. The development of formulation-process couples is then essential for their valorization, in order to obtain a structure allowing them to reach properties compatible with future uses, and to make them usable as raw material for 3D printing. For this purpose, we have studied the formulation of PET/PE model blends representative of multi-layered plastic packaging waste streams. We will discuss our results to assess the effectiveness of various processes on properties. Especially, we will introduce the benefits for both morphology and mechanical properties of adding more LDPE to the blends, rather than trying to valorize PET/PE multi-layers as such. Indeed, the presence of LDPE in a PET matrix may have a negative impact on PET properties, severely limiting its mechanical properties. Conversely, the presence of PET in a LDPE matrix can act as a reinforcement. Finally, we will present the valorization of PET/PE blends by 3D printing and the challenges associated with blends printing
Effect of the formation of hydantoin in aspartate-based polyurea networks
No full textInternational audienceThe paper aims to give an understanding of the structure of crosslinked polyurea coatings based on aspartate estersand to link it with changes in mechanical properties observed over time. Model systems representative of thenetworks are synthesized and analyzed by NMR. It allows to put forward the formation of hydantoin by the reactionof the urea groups with the neighboring ester groups. It is seen that the presence of acid within the networkaccelerates this phenomenon. A feature of the work deals with the influence of hydantoin formation on mechanicalproperties. Depending on the presence of plasticizers, it appears that hydantoin formation leads to differentmechanical properties changes
A new approach to agglomeration problems
No full textIn this paper, we study a location problem with positive externalities. We define a new transferable utility game, considering there is no restriction on the transfer of benefits between firms. We prove that the core of this game is non-empty, provide an expression for it, and an axiomatic characterization. We also study several core allocations, selected by means of a certain bankruptcy problem
Differential effect of three types of exoskeletons and handling height on muscular activity, postural control and perceived effort during simulated bedside mobilization task
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Full Key-Recovery Cubic-Time Template Attack on Classic McEliece Decapsulation
No full textInternational audienceClassic McEliece is one of the three code-based candidates in the fourth round of the NIST post-quantum cryptography standardization process in the Key Encapsulation Mechanism category. As such, its decapsulation algorithm is used to recover the session key associated with a ciphertext using the private key. In this article, we propose a new side-channel attack on the syndrome computation in the decapsulation algorithm that recovers the private key, which consists of the private Goppa polynomial g and the permuted support L. The attack relies on both practical aspects and theoretical contributions, namely that the side-channel distinguisher can accurately discriminate elements of the permuted support L, while relying only on a standard noisy Hamming weight leakage assumption and that there exists a cubic-time algorithm that uses this information to recover the private Goppa polynomial g. Compared with previous work targeting the Classic McEliece private key, this drastically improves both on the assumptions made in the attacker model and on the overall efficiency of the key-recovery algorithm. We have carried out the attack in practice on a microcontroller target running the reference implementation of Classic McEliece, and make the full attack source code available
Finite-dimensional pseudofinite groups of small dimension, without CFSG
No full textInternational audienceAny simple pseudofinite group G is known to be isomorphic to a (twisted) Chevalley group over a pseudofinite field. This celebrated result mostly follows from the work of Wilson in 1995 and heavily relies on the classification of finite simple groups (CFSG). It easily follows that G is finite-dimensional with additive and fine dimension and, in particular, that if dim(G)=3 then G is isomorphic to PSL(2,F) for some pseudofinite field F. We describe pseudofinite finite-dimensional groups when the dimension is fine, additive and <4 and, in particular, show that the classification G isomorphic to PSL(2,F) is independent from CFSG.pseudofinite groups, finite-dimensional groups, classification of finite simple groups, simple groups of Lie typ
Solvable groups and affine actions on the line
No full textInternational audienceWe prove a structural result for orientation-preserving actions of finitely generated solvable groups on real intervals, considered up to semi-conjugacy. As applications we obtain new answers to a problem first considered by J. F. Plante, which asks under which conditions an action of a solvable group on a real interval is semi-conjugate to an action on the line by affine transformations. We show that this is always the case for actions by diffeomorphisms on closed intervals. For arbitrary actions by homeomorphisms, for which this result is no longer true (as shown by Plante), we show that a semi-conjugacy to an affine action still exists in a local sense, at the level of germs near the endpoints. Finally for a vast class of solvable groups, including all solvable linear groups, we show that the family of affine actions on the line is robust, in the sense that any action by homeomorphisms on the line which is sufficiently close to an affine action must be semi-conjugate to an affine action. This robustness fails for general solvable groups, as illustrated by a counterexample
Examining methodological influences on the rhythmic priming effect: A commentary on Kim, McLaren, and Lee (2024)
No full textInternational audienceThe rhythmic priming effect (RPE) refers to improved language performance (typically grammaticality judgements) following regular rhythmic primes compared to various control conditions. This effect has been observed primarily in French, but also in English and Hungarian. However, a recent implementation by Kim, McLaren & Lee (2024), aiming to replicate the RPE in English (Chern, Tillmann, Vaughan & Gordon, 2018), was not successful, inviting a discussion about the conditions under which the RPE could be observed. We here discuss features of Kim et al.'s (2024) implementation that might have reduced the probability of observing the RPE. Compared to Chern et al. (2018), and numerous other studies reporting the RPE, additional delays after the primes and before each sentence were introduced by Kim et al. (2024). This change might have limited beneficial prime effects, which persist, but decay over time. Further, their instruction to "relax and have some rest" might have reduced attentive processing of the primes and related entrainment. Finally, their sample was small (n =16 per experiment) and with a large age range for investigating typically developing children (7-12y), potentially reducing experimental effects due to development-related individual variations. These methodological changes and sample characteristics are discussed in relation to previous research on the RPE, and entrainment in general. This discussion prompts the need for future research to investigate conditions leading to the RPE, with the aim to shed light on underlying mechanisms. Better understanding the RPE will be critical for the use of rhythmic priming within clinical and educational settings
Long term noninvasive respiratory support in children with OSA-I and OSA-II: data of a nation-wide study
No full textInternational audiencePurposeThe aim of the study was to analyze the characteristics of otherwise healthy children with obstructive sleep apnea (OSA; OSA-I) and children with OSA and non-syndromic obesity (OSA-II) treated with long term continuous positive airway pressure (CPAP) or noninvasive ventilation (NIV) in 2019 in France.MethodsData were collected from a national survey on paediatric home noninvasive ventilatory support. CPAP/NIV initiation criteria and duration, age at CPAP/NIV initiation, equipment used and CPAP/NIV settings, and objective compliance were analyzed.ResultsPatients with OSA-I and OSA-II represented 6% (n=84, 71% males) and 10% (n=144, 72% males) of the national cohort, respectively. The apnea-hypopnea index (63% vs 76%), alone or combined with nocturnal gas exchange (25% vs 21%, for OSA-II and OSA-I patients respectively) were used as initiation criteria of CPAP/NIV. OSA-II patients were older at CPAP/NIV initiation (mean age 11.0±4.0 vs 6.8±4.5 years, p<0.001) and were treated for a longer time (2.3±2.6 vs 1.3±1.5 years, p=0.008) than OSA-I patients. NIV was used in 6% of OSA-I patients and 13% of OSA-II patients (p=0.142). Both groups used preferentially a nasal mask. Mean CPAP level was higher in OSA-II patients as compared to OSA-I patients (8.7±2.0 vs 7.7±2.4 cmH2O, p=0.02). Objective compliance was comparable (mean use 6.8±2.6 vs 5.9±3.0 hours/night in OSA-I and OSA-II, respectively, p=0.054).ConclusionSix and 10% of children treated with long term CPAP/NIV in France in 2019 had OSA-I and OSA-II, respectively. Both groups were preferentially treated with CPAP and were comparable except for age, with OSA-II patients being older at CPAP/NIV initiation
Machine learning-based pulse wave analysis for classification of circle of Willis topology: An in silico study with 30,618 virtual subjects
No full textInternational audienceBackground and Objective: The topology of the circle of Willis (CoW) is crucial in cerebral circulation and significantly impacts patient management. Incomplete CoW structures increase stroke risk and post-stroke damage. Current detection methods using computed tomography and magnetic resonance scans are often invasive, time-consuming, and costly. This study investigated the use of machine learning (ML) to classify CoW topology through arterial blood flow velocity pulse waves (PWs), which can be noninvasively measured with Doppler ultrasound. Methods: A database of in silico PWs from 30,618 virtual subjects, aged 25 to 75 years, with complete and incomplete CoW topologies was created and validated against in vivo data. Seven ML architectures were trained and tested using 45 combinations of carotid, vertebral and brachial artery PWs, with varying levels of artificial noise to mimic real-world measurement errors. SHapley Additive exPlanations (SHAP) were used to interpret the predictions made by the artificial neural network (ANN) models. Results: A convolutional neural network achieved the highest accuracy (98%) for CoW topology classification using a combination of one vertebral and one common carotid velocity PW without noise. Under a 20% noise-tosignal ratio, a multi-layer perceptron model had the highest prediction rate (79%). All ML models performed best for topologies lacking posterior communication arteries. Mean and peak systolic velocities were identified as key features influencing ANN predictions. Conclusions: ML-based PW analysis shows significant potential for efficient, noninvasive CoW topology detection via Doppler ultrasound. The dataset, post-processing tools, and ML code, are freely available to support further research.</div