Models of rotating boson stars and geodesics around them: new type of orbits

We have developed a highly accurate numerical code capable of solving the coupled Einstein-Klein-Gordon system, in order to construct rotating boson stars in general relativity. Free fields and self-interacting fields, with quartic and sextic potentials, are considered. In particular, we present the first numerical solutions of rotating boson stars with rotational quantum number $k=3$ and $k=4$, as well as the first determination of the maximum mass of free-field boson stars with $k=2$. We have also investigated timelike geodesics in the spacetime generated by a rotating boson star for $k=1$, $2$ and $3$. A numerical integration of the geodesic equation has enabled us to identify a peculiar type of orbits: the zero-angular-momentum ones. These orbits pass very close to the center and are qualitatively different from orbits around a Kerr black hole. Should such orbits be observed, they would put stringent constraints on astrophysical compact objects like the Galactic center

Overview of Industrial Policy and Institutions in Africa

This paper reviews the role played by institutions, including political and economic institutions, in industrial development in Africa. The paper notes that African countries are still struggling to structurally transform their economies and to stimulate inclusive development despite some industrial policy efforts. The lagging performance in industrial sector in Africa can be mainly explained by the lack of institutional frameworks impede good coordination and monitoring of industrial policies. The paper argues that industrial policies are critical to correct the widespread existence of market and coordination failures and the role of governments and institutions in Africa in regulating these market failures should be a priority for the industrialization of the continent. The paper also analyzes the evolution of industrial policy in Africa during the last decade in terms of constraints and structural reforms to industrialization in Africa. It appears that constraints faced by industrial sector in Africa and that need to be addressed includes productive, trade, institutional, and human/technical capacity constraints as well as financial constraints. Structural reforms include promoting green industrialization and gender parity. Keywords: Industrial Policy; Institutions; Structural Chang

Control What You Include! Server-Side Protection against Third Party Web Tracking

Third party tracking is the practice by which third parties recognize users accross different websites as they browse the web. Recent studies show that 90% of websites contain third party content that is tracking its users across the web. Website developers often need to include third party content in order to provide basic functionality. However, when a developer includes a third party content, she cannot know whether the third party contains tracking mechanisms. If a website developer wants to protect her users from being tracked, the only solution is to exclude any third-party content, thus trading functionality for privacy. We describe and implement a privacy-preserving web architecture that gives website developers a control over third party tracking: developers are able to include functionally useful third party content, the same time ensuring that the end users are not tracked by the third parties

(R1886) Effect of Aggregation Function in MOMA-Plus Method For Obtaining Pareto Optimal Solutions

In this work, we have proposed some variants of MOMA-Plus method that we have numerically tested for the resolution of nonlinear multiobjective optimization problems. This MOMA-Plus method and variants differ from each other by the choice of aggregation functions in order to reduce the number of objective functions. The theoretical results allowing us to use these aggregation functions to transform multiobjective optimization problems into single objective optimization problems are proved by two theorems. This study has highlighted the advantages of each aggregation function according to the type of Pareto front of the optimization problem. Six benchmarks test problems have been solved in this work by each of these methods and a comparative study was carried out through the performance indicators which are the differentiation with Pareto front, the convergence to the Pareto front and distributivity on the Pareto front. This allowed us to classify these methods on these benchmarks by using the Graphical Analysis for Interactive Assistance (GAIA) method

AN INTERCULTURAL PERSPECTIVE OF ERROR CORRECTION AND STUDENT LEARNING IN ENGLISH AS A FOREIGN LANGUAGE CONTEXT

Error correction is an essential component of language learning. It takes different forms that can affect language learning either positively or negatively. In the foreign language learning context, where the classroom is the only environment where the learners encounter the target language, error correction must be central to learning. It can easily be a demotivation factor to language learning. In this paper, the author examines error correction in High schools in Burkina Faso. The article explores how teachers deal with error corrections in the classroom and error treatment on student learning. The author conducted a qualitative study using classroom observations and interviews with teachers and students as data collection methods.  Article visualizations

EmPoWeb: Empowering Web Applications with Browser Extensions

Browser extensions are third party programs, tightly integrated to browsers, where they execute with elevated privileges in order to provide users with additional functionalities. Unlike web applications, extensions are not subject to the Same Origin Policy (SOP) and therefore can read and write user data on any web application. They also have access to sensitive user information including browsing history, bookmarks, cookies and list of installed extensions. Extensions have a permanent storage in which they can store data and can trigger the download of arbitrary files on the user's device. For security reasons, browser extensions and web applications are executed in separate contexts. Nonetheless, in all major browsers, extensions and web applications can interact by exchanging messages. Through these communication channels, a web application can exploit extension privileged capabilities and thereby access and exfiltrate sensitive user information. In this work, we analyzed the communication interfaces exposed to web applications by Chrome, Firefox and Opera browser extensions. As a result, we identified many extensions that web applications can exploit to access privileged capabilities. Through extensions' APIS, web applications can bypass SOP, access user cookies, browsing history, bookmarks, list of installed extensions, extensions storage, and download arbitrary files on the user's device. Our results demonstrate that the communications between browser extensions and web applications pose serious security and privacy threats to browsers, web applications and more importantly to users. We discuss countermeasures and proposals, and believe that our study and in particular the tool we used to detect and exploit these threats, can be used as part of extensions review process by browser vendors to help them identify and fix the aforementioned problems in extensions.Comment: 40th IEEE Symposium on Security and Privacy May 2019 Application security; Attacks and defenses; Malware and unwanted software; Mobile and Web security and privacy; Privacy technologies and mechanism

Analyse de la dynamique de la végétation du Burkina Faso par utilisation de séries temporelles d’images FAPAR

La dynamique de la végétation des secteurs phytogéographiques est un paramètre clé pour la gestion durable des ressources végétales au Burkina Faso. Cette étude vise à mettre en évidence les changements affectant la productivité de la végétation au Burkina Faso sur la période 1999-2019. Les métriques de la phénologie de la végétation dont la valeur du maximum (Vmx) et la valeur moyenne (Vav) ont été extraites sur une série temporelle d’images FAPAR pour le calcul des variables statistiques. Les variables statistiques utilisées pour l’appréciation globale du changement de la production de la végétation sont le coefficient de variation, la pente des droites de tendance et l’anomalie standardisée (Z-score). Les résultats indiquent que de forts gains de la productivité de la végétation ont été observés dans le domaine sahélien et le secteur nord-soudanien. Cela est lié à l’expansion des zones de cultures et à une faible persistance des années de déficit de la production végétale sur la période de la nouvelle normale de précipitation (1991-2020). Cependant, le secteur sud-soudanien marqué par des formations ligneuses abondantes a enregistré de faibles gains de la production de la végétation. La cartographie utilisant les métriques du maximum et de la moyenne donne une tendance globale, mais ne fournit pas assez de détail sur le changement affectant les différentes bandes de végétation. Une combinaison des métriques phénologiques de la végétation au moyen de modèle construit sur la base de biomasse végétale collectée sur le terrain pourrait améliorer ces résultats de la cartographie de zones de changement des secteurs phytogéographiques