Investigating capitalism aversion

There are two non-mutually exclusive theories of individual variations in pro-capitalism opinions. The first theory views pro-capitalism opinions as self-serving: Individuals are opposed to market forces when they threaten their economic rents. The second theory views differences in such opinions as reflecting genuine disagreement on the efficiency of various economic systems. Using individual data, we investigate the validity of both theories, focusing on attitudes toward private ownership, private profit and competition. We find evidence that the first theory explains some of the variations in attitudes. However, consistent with the second theory, we also find evidence of individual learning about the comparative virtues of economic systems. The learning is slow, home-biased and path-dependent. Long-run cultural and historical determinants of pro-market attitudes, such as religion and legal origins, explain more than 40% of the cross-country variations in capitalism aversion. Last, we provide tentative evidence that at the country level, pro-market opinions affect the nature of economic institutions. Our results suggest that the feasibility of economic reform does not depend solely on its impact on the distribution of rents; ideological a-prioris are likely to be important as well. — Augustin Landier, David Thesmar and Mathias Thoeni

XRay: Enhancing the Web's Transparency with Differential Correlation

Today's Web services - such as Google, Amazon, and Facebook - leverage user data for varied purposes, including personalizing recommendations, targeting advertisements, and adjusting prices. At present, users have little insight into how their data is being used. Hence, they cannot make informed choices about the services they choose. To increase transparency, we developed XRay, the first fine-grained, robust, and scalable personal data tracking system for the Web. XRay predicts which data in an arbitrary Web account (such as emails, searches, or viewed products) is being used to target which outputs (such as ads, recommended products, or prices). XRay's core functions are service agnostic and easy to instantiate for new services, and they can track data within and across services. To make predictions independent of the audited service, XRay relies on the following insight: by comparing outputs from different accounts with similar, but not identical, subsets of data, one can pinpoint targeting through correlation. We show both theoretically, and through experiments on Gmail, Amazon, and YouTube, that XRay achieves high precision and recall by correlating data from a surprisingly small number of extra accounts.Comment: Extended version of a paper presented at the 23rd USENIX Security Symposium (USENIX Security 14

De la nécessité de créer des bibliothèques scientifiques-industrielles ou du moins d\u27ajouter aux bibliothèques publiques une division des sciences appliquées aux arts et à l\u27industrie.

« Document numérisé pour l\u27ENSSIB » - Ce document est destiné aux professionnels. Il se présente comme un fervent plaidoyer en faveur de la création de bibliothèques spécialisées dans les sciences et l\u27industrie. L\u27auteur propose dans une première partie divers témoignages attestant la nécessité d\u27une telle initiative. Puis il dresse un état des lieux de la représentation de ces domaines dans les bibliothèques de l\u27époque en pointant le faible nombre d\u27établissements disposant d\u27un fonds sur ces sujets. Il offre ensuite une autre série de témoignages et autres discours favorables à son projet. Il appuie son propos en détaillant quelques points techniques relatifs à la constitution de fonds spécifiques, notamment le prix de revient de telles bibliothèques. Enfin, il termine son exposé en fournissant un catalogue des livres qui composeraient idéalement une bibliothèque scientifique-industrielle. Au-delà de l\u27intérêt professionnel, ce document est particulièrement intéressant du point de vue historique car il s\u27inscrit parfaitement dans le contexte de rénovation socio-économique profonde qui survient au XIXe siècle et voit l\u27avènement de la société industrielle, largement tournée vers les progrès scientifiques

Microplastic fibers affect dynamics and intensity of CO2 and N2O fluxes from soil differently

Microplastics may affect soil ecosystem functioning in critical ways, with previously documented effects including changes in soil structure and water dynamics; this suggests that microbial populations and the processes they mediate could also be affected. Given the importance for global carbon and nitrogen cycle and greenhouse warming potential, we here experimentally examined potential effects of plastic microfiber additions on CO2 and N2O greenhouse gas fluxes. We carried out a fully factorial laboratory experiment with the factors presence of microplastic fibers (0.4% w/w) and addition of urea fertilizer (100 mg N kg− 1) using one target soil. The conditions in an intensively N-fertilized arable soil were simulated by adding biogas digestate at the beginning of the incubation to all samples. We continuously monitored CO2 and N2O emissions from soil before and after urea application using a custom-built flow-through steady-state system, and we assessed soil properties, including soil structure. Microplastics affected soil properties, notably increasing soil aggregate water-stability and pneumatic conductivity, and caused changes in the dynamics and overall level of emission of both gases, but in opposite directions: overall fluxes of CO2 were increased by microplastic presence, whereas N2O emission were decreased, a pattern that was intensified following urea addition. This divergent response is explained by effects of microplastic on soil structure, with the increased air permeability likely improving O2 supply: this will have stimulated CO2 production, since mineralization benefits from better aeration. Increased O2 would at the same time have inhibited denitrification, a process contributing to N2O emissions, thus likely explaining the decrease in the latter. Our results clearly suggest that microplastic consequences for greenhouse gas emissions should become an integral part of future impact assessments, and that to understand such responses, soil structure should be assessed

Modélisation Prospective De L'Occupation Du Sol d’un Espace A Forte Pression Anthropique : Cas Du Bassin Versant Du Massili A Gonsé (Burkina Faso)

L’agriculture extensive et l’étalement urbain soulèvent aujourd’hui des questions sur l’évolution des modes d’occupation des terres et leurs effets sur le milieu. L’objectif de la présente étude est d’évaluer les changements dans la dynamique de l’occupation des terres et d’examiner les modifications futures attendues dans le bassin versant du Massili à Gonsé. L’étude s’appuie sur le traitement des images Landsat (1991 ; 2007) et 2019 (référence), les images SRTM 30 m, les types de sols et les données de population. Le logiciel Terrset (LCM) a été utilisé pour simuler les changements dans l’occupation des terres (2050). L’analyse des résultats de la simulation montre que sous le scénario « LULC-A », en 2050, les savanes, les champs, les eaux de surface, les formations ripicoles et les champs diminueront de surface respectivement de 57,58 %, 23,57 % ; 21,63 % ; 9 % et 5,70 % alors que l’habitat augmentera de 99 % par rapport à la base (2019). Sous le scénario « LULC-B », en 2050, la modélisation indique que les sols nus, les champs et les eaux de surface diminueront respectivement de 83,76 % ; de 37,03 % ; de 22,90 % alors que les savanes, l’habitat et les formations ripicoles augmenteront respectivement de 166,10 %, de 75,05 % et de 71,63 % par rapport à la référence. Les résultats de cette étude apparaissent donc comme un outil d’aide à la décision dans l’aménagement du territoire

Biquadratic exchange interactions in two-dimensional magnets

Magnetism in recently discovered van der Waals materials has opened several avenues in the study of fundamental spin interactions in truly two-dimensions. A paramount question is what effect higher-order interactions beyond bilinear Heisenberg exchange have on the magnetic properties of few-atom thick compounds. Here we demonstrate that biquadratic exchange interactions, which is the simplest and most natural form of non-Heisenberg coupling, assume a key role in the magnetic properties of layered magnets. Using a combination of nonperturbative analytical techniques, non-collinear first-principles methods and classical Monte Carlo calculations that incorporate higher-order exchange, we show that several quantities including magnetic anisotropies, spin-wave gaps and topological spin-excitations are intrinsically renormalized leading to further thermal stability of the layers. We develop a spin Hamiltonian that also contains antisymmetric exchanges (e.g., Dzyaloshinskii–Moriya interactions) to successfully rationalize numerous observations, such as the non-Ising character of several compounds despite a strong magnetic anisotropy, peculiarities of the magnon spectrum of 2D magnets, and the discrepancy between measured and calculated Curie temperatures. Our results provide a theoretical framework for the exploration of different physical phenomena in 2D magnets where biquadratic exchange interactions have an important contribution

Properties and dynamics of meron topological spin textures in the two-dimensional magnet CrCl3

Merons are nontrivial topological spin textures highly relevant for many phenomena in solid state physics. Despite their importance, direct observation of such vortex quasiparticles is scarce and has been limited to a few complex materials. Here we show the emergence of merons and antimerons in recently discovered two-dimensional (2D) CrCl3 at zero magnetic field. We show their entire evolution from pair creation, their diffusion over metastable domain walls, and collision leading to large magnetic monodomains. Both quasiparticles are stabilized spontaneously during cooling at regions where in-plane magnetic frustration takes place. Their dynamics is determined by the interplay between the strong in-plane dipolar interactions and the weak out-of-plane magnetic anisotropy stabilising a vortex core within a radius of 8-10 nm. Our results push the boundary to what is currently known about non-trivial spin structures in 2D magnets and open exciting opportunities to control magnetic domains via topological quasiparticles.Comment: Nature Communications 12, 185 (2021). Editors' Highlights sectio

Vers une plus grande transparence du Web

International audienceDe plus en plus les géants du Web (Amazon, Google et Twitter en tête) recourent a la manne des « Big data » : ils collectent une myriade de données qu'ils exploitent pour leurs algorithmes de recommandation personnalisée et leurs campagnes publicitaires. Pareilles méthodes peuvent considérablement améliorer les services rendus a leurs utilisateurs, mais leur opacité fait débat. En effet, il n'existe pas a ce jour d'outil suffisamment robuste qui puisse tracer sur le Web l'usage des données et des informations sur un utilisateur par des services en ligne. Motivés par ce manque de transparence, nous avons développé un prototype du nom d'XRay, et qui peut prédire quelle donnée parmi toutes celles présentes dans un compte utilisateur est responsable de la réception d'une publicité. Dans cet article, nous présentons son principe ainsi que les résultats de nos premières expérimentations. Nous introduisons dans le même temps le tout premier modèle théorique pour le problème de la transparence du Web, et nous interprétons les performances d'Xray a la lumière de nos résultats obtenus dans ce modèle. En particulier, nous démontrons qu'un nombre θ(log N) de comptes utilisateurs auxiliaires, remplis selon un procédé aléatoire , suffisent a déterminer quelle donnée parmi les N en présence a causé la réception d'une publicité. Nous aborderons brièvement les extensions possibles, et quelques problèmes ouverts