Humiliations scolaires :: origines, développement et remédiations

Au moment où les différents discours sur le harcèlement scolaire éclatent au grand jour dans notre société, ce travail aborde le thème de l’humiliation scolaire, phénomène peu connu, mais étroitement lié au harcèlement scolaire. J’ai choisi de me placer du point de vue des enseignants, afin de comprendre les tenants et aboutissants qui les pousseraient à utiliser des mécanismes néfastes contre leurs élèves, le plus souvent involontairement. Le but de cette recherche n’est ni une morale ou un pamphlet, ni dans l’optique de pointer l’école du doigt, mais de se rendre compte que ce phénomène existe et qu’il est nécessaire d’en prendre conscience, afin de permettre aux élèves d’évoluer dans un climat scolaire affectivement sécurisant, de sorte à optimiser leurs apprentissages. Ceci en m’approchant d’enseignants prêts à partager leurs expériences, et à analyser leurs pratiques professionnelles. Les propos des enseignants mettent en exergue que l’humiliation a malheureusement sa place au sein des établissements scolaires. Il s’agit donc de se sentir concerné par cette thématique et de se remettre en question sur sa pratique, puisque notre statut d’enseignant joue, le plus souvent, un rôle primordial sur la vie de nos élèves

Cyber harcèlement et les besoins émis par les jeunes victimes

L’utilisation des Smartphones et des réseaux sociaux est, à ce jour, très présent dans la vie des jeunes. Avec ce type d’outils, l’auteur n’est pas seulement consommateur mais aussi acteur puisqu’il crée des contenus. Pour les adolescents, ce sont des moyens de créer des liens sociaux et de partager. Face à l’utilisation accrue des nouvelles technologies, le cyber harcèlement a fait son apparition depuis quelques années dans notre société. Nous sommes dans une phase où les jeunes se sentent experts de ces outils et où la génération antécédente n’est pas suffisamment à l’aise pour concevoir les risques et les problèmes que peut engendrer une utilisation peu contrôlée. Nous avons donc voulu mieux comprendre les enjeux du cyber harcèlement et ses conséquences car malgré les nombreuses instances d’aides et de prévention, ce phénomène reste toujours actuel et encore tabou

Learned transform compression with optimized entropy encoding

We consider the problem of learned transform compression where we learn both, the transform as well as the probability distribution over the discrete codes. We utilize a soft relaxation of the quantization operation to allow for back-propagation of gradients and employ vector (rather than scalar) quantization of the latent codes. Furthermore, we apply similar relaxation in the code probability assignments enabling direct optimization of the code entropy. To the best of our knowledge, this approach is completely novel. We conduct a set of proof-of concept experiments confirming the potency of our approaches.Comment: Neural Compression Workshop @ ICLR 202

Quantum scars as embeddings of weakly broken Lie algebra representations

Recently, much effort has focused on understanding weak ergodicity breaking in many-body quantum systems that could lead to wavefunction revivals in their dynamics far from equilibrium. An example of such nonthermalizing behavior is the phenomenon of quantum many-body scars, which has been experimentally observed in Rydberg-atom quantum simulators. Here, the authors show that many-body scars can generally be viewed as forming approximate subspaces of “broken” Lie algebra representations. Furthermore, they use an iterative process to identify perturbations which “correct” the broken Lie algebra, resulting in improved quantum revivals from special initial states. The description of embedded Lie algebra representations unifies several theoretical models, which feature exact many-body scars, with experimentally realized models, such as the constrained Rydberg-atom system, where scars only form an approximate Lie algebra representation. We present an interpretation of scar states and quantum revivals as weakly “broken” representations of Lie algebras spanned by a subset of eigenstates of a many-body quantum system. We show that the PXP model, describing strongly interacting Rydberg atoms, supports a “loose” embedding of multiple su(2) Lie algebras corresponding to distinct families of scarred eigenstates. Moreover, we demonstrate that these embeddings can be made progressively more accurate via an iterative process which results in optimal perturbations that stabilize revivals from arbitrary charge density wave product states, |Zn〉, including ones that show no revivals in the unperturbed PXP model. We discuss the relation between the loose embeddings of Lie algebras present in the PXP model and recent exact constructions of scarred states in related models

Embedding semiclassical periodic orbits into chaotic many-body Hamiltonians

Protecting coherent quantum dynamics from chaotic environment is key to realizations of fragile many-body phenomena and their applications in quantum technology. We present a general construction that embeds a desired periodic orbit into a family of non-integrable many-body Hamiltonians, whose dynamics is otherwise chaotic. Our construction is based on time dependent variational principle that projects quantum dynamics onto a manifold of low-entangled states, and it complements earlier approaches for embedding non-thermal eigenstates, known as quantum many-body scars, into thermalizing spectra. By designing terms that suppress "leakage" of the dynamics outside the variational manifold, we engineer families of Floquet models that host exact scarred dynamics, as we illustrate using a driven Affleck-Kennedy-Lieb-Tasaki model and a recent experimental realization of scars in a dimerized superconducting qubit chain.Comment: 6+13 page

Evaluation of Immunization Policies for PeaceKeeping Missions

This article first examines data bases available to assess the risk of vaccine-preventable diseases (VPD). In the second part, immunization recommendations and practices are briefly evaluated in view of the risk of exposure to VPD and of the efficacy and safety of available vaccine

Superdiffusive Energy Transport in Kinetically Constrained Models

Universal nonequilibrium properties of isolated quantum systems are typically probed by studying transport of conserved quantities, such as charge or spin, while transport of energy has received considerably less attention. Here, we study infinite-temperature energy transport in the kinetically-constrained PXP model describing Rydberg atom quantum simulators. Our state-of-the-art numerical simulations, including exact diagonalization and time-evolving block decimation methods, reveal the existence of two distinct transport regimes. At moderate times, the energy-energy correlation function displays periodic oscillations due to families of eigenstates forming different su(2) representations hidden within the spectrum. These families of eigenstates generalize the quantum many-body scarred states found in previous works and leave an imprint on the infinite-temperature energy transport. At later times, we observe a broad superdiffusive transport regime that we attribute to the proximity of a nearby integrable point. Intriguingly, strong deformations of the PXP model by the chemical potential do not restore diffusion, but instead lead to a stable superdiffusive exponent $z\approx3/2$. Our results suggest constrained models to be potential hosts of novel transport regimes and call for developing an analytic understanding of their energy transport.Comment: 13 pages, 12 figure

Lack of Leukocyte Migration Inhibition by Hepatitis B Antigen and Normal Nonspecific Immunoreactivity in Asymptomatic Carriers

The immune response to hepatitis B surface antigen (RBs Ag) was studied in 25 asymptomatic carriers by the leukocyte migration-inhibition (LMI) test in agarose. In the presence of purified RBs Ag, inhibition was demonstrated in only four of 25 carriers, in contrast to 24 of 28 patients who cleared the antigen after acute infection with hepatitis B. Tuberculin purified protein derivative (PPD) was also used as an antigen for the LMI test in these carriers. Inhibition was demonstrated in only 12 of 25 individuals who had positive PPD skin tests, in contrast to all of 14 normal noncarrier individuals with positive PPD skin tests and none of 12 normal noncarrier individuals with negative PPD skin tests. A nonspecific immunological investigation of the asymptomatic carriers gave normal results. The lack of an immune response to HBs Ag was thought to be responsible for the persistence of the antigen and also for the absence of symptom