A new pretopological way of identifying spreaders in propagation diffusion phenomena

In a world that's increasingly connected, many crises are related to propagation phenomena where we need to either repress the spreading (e.g. epidemics, computer viruses, fake news...) or try to accelerate it (e.g. the diffusion of a new anti-virus patch). A good understanding of such phenomena involves a knowledge of both the structure of the whole system and the specifics of the transmission process. The standard way to deal with the former has been through a characterization of the structure by the use of networks, where nodes are the components of the system where the propagation occurs, and links exist between them if there's a possibility of transmission from one component to the other. This allows to identify the super-spreaders (i.e. components that diffuse in a disproportionally large amount) as nodes with certain particular network properties. Here we propose the use of pretopology as a framework to characterize the structure of a system, as well as a new pretopological metric for the identification of super-spreaders. Since the metric can easily be transformed into an equivalent network metric, it is easy to compare its performance with some of the classical network indices of node importance. The relevance of the metric is tested by the use of some standard agent-based models of epidemics and opinion dynamics. Finally, a pretopological model of opinion diffusion is also proposed and studied

Your most telling friends: Propagating latent ideological features on Twitter using neighborhood coherence

Multidimensional scaling in networks allows for the discovery of latent information about their structure by embedding nodes in some feature space. Ideological scaling for users in social networks such as Twitter is an example, but similar settings can include diverse applications in other networks and even media platforms or e-commerce. A growing literature of ideology scaling methods in social networks restricts the scaling procedure to nodes that provide interpretability of the feature space: on Twitter, it is common to consider the sub-network of parliamentarians and their followers. This allows to interpret inferred latent features as indices for ideology-related concepts inspecting the position of members of parliament. While effective in inferring meaningful features, this is generally restrained to these sub-networks, limiting interesting applications such as country-wide measurement of polarization and its evolution. We propose two methods to propagate ideological features beyond these sub-networks: one based on homophily (linked users have similar ideology), and the other on structural similarity (nodes with similar neighborhoods have similar ideologies). In our methods, we leverage the concept of neighborhood ideological coherence as a parameter for propagation. Using Twitter data, we produce an ideological scaling for 370K users, and analyze the two families of propagation methods on a population of 6.5M users. We find that, when coherence is considered, the ideology of a user is better estimated from those with similar neighborhoods, than from their immediate neighbors.Comment: 8 pages, 2020 ASONAM Conferenc

Combining pre-trained Vision Transformers and CIDER for Out Of Domain Detection

Out-of-domain (OOD) detection is a crucial component in industrial applications as it helps identify when a model encounters inputs that are outside the training distribution. Most industrial pipelines rely on pre-trained models for downstream tasks such as CNN or Vision Transformers. This paper investigates the performance of those models on the task of out-of-domain detection. Our experiments demonstrate that pre-trained transformers models achieve higher detection performance out of the box. Furthermore, we show that pre-trained ViT and CNNs can be combined with refinement methods such as CIDER to improve their OOD detection performance even more. Our results suggest that transformers are a promising approach for OOD detection and set a stronger baseline for this task in many context

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

La prétopologie, un outil mathématique pour la structuration des systèmes complexes : méthodes, algorithmes et applications

When we study a complex system it is natural to be interested in the structure of its elements, as opposed to just caring about the individual characteristics of the components. The traditional way to deal with this issue has been through a characterization of the structure by the use of graphs, where nodes represent the components of the system, and an edge exists between two of them if there is a relation connecting them. The theory is nevertheless only appropriate for the description of systems with binary underlying relations between the components. We propose here the use of pretopology to effectively treat the case where connections exist between an element and a group. Our contributions include a formalization of a pretopological space in terms of a simple group of rules over a set of networks. This allow us to economically store a pretopological space, and to effectively study the complexity of the algorithms that have been proposed. Some of these algorithms were improved. Some applications are developed. The first of them is a Python library where all of the previously reviewed algorithms are implemented. After presenting in a general manner the faculties of the library, we use it to study some diffusion phenomena with the help of some agent based models. We finish using some of the notions introduced here to develop a clusterization algorithm, that not only performs on a par with the state of the art on some artificial geometrical data, but also has the advantage of being immediately generalizable to non-metrical spaces.En étudiant un système complexe il est naturel de s’interroger sur la structuration de ses éléments, en opposition à s’intéresser seulement aux caractéristiques individuelles des composantes. La manière traditionnelle d’aborder cette problématique a été de caractériser la structure à l’aide de un graphe, où les sommets représentent les composants du système, et un lien connecte deux composants s’il existe une relation entre l’une et l’autre. Cependant cette théorie est pertinente uniquement pour caractériser des systèmes où les rapports sous-jacents sont binaires. Nous proposons ici l’utilisation de la prétopologie afin de traiter le cas où des liens existent entre un élément et un groupe. Nos contributions incluent la formalisation d’un espace prétopologique comme une combinaison de réseaux et de seuils, avec des règles élémentaires pour l’appartenance d’un élément à une adhérence. Ceci nous permet de stocker économiquement un espace, et d’étudier efficacement la complexité des algorithmes existants. Quelques algorithmes ont été améliorés. Quelques applications on été développées. La première a été la création d’une librairie prétopologique en Python. La librairie est ensuite utilisée pour étudier quelques problèmes liés à la diffusion au sein d’un système. La troisième et dernière application consiste à utiliser la prétopologie dans le contexte du partitionnement de données

Articulation entre cadres et registres de représentation des équations différentielles dans un environnement de géométrie dynamique

Notre travail tente de frayer une voie d'accès envisageable pour l'étude de la modélisation dans le contexte du cours d'équations différentielles au Mexique. L'identification de certaines contraintes nous a conduit à nous intéresser au rôle, dans la modélisation, des articulations entre cadres et registres de représentation des équations différentielles. Notre hypothèse est que "la démarche de modélisation par des équations différentielles requiert une certaine maîtrise de ces articulations". En considérant les outils de Cabri, nous avons conçu une ingénierie didactique qui favorise ces articulations ainsi qu'une modélisation mathématique. La mise en place de cette ingénierie nous a permis identifier des difficultés des étudiants pour faire l'articulation algébrique et graphique

Articulation des registres graphique et symbolique pour l'étude des équations différentielles avec Cabri géomètre (analyse des difficultés des étudiants et du rôle du logiciel)

L'enseignement des équations différentielles privilégie l'approche algébrique, malgré l'existence des approches numérique et qualitative. Dans l'approche algébrique le lien entre les registres symbolique et graphique est indirect: il passe par l'expression symbolique des solutions. En revanche, 1 mise en relation directe de ces registres requiert la mobilisation de connaissances de divers cadres: fonctions, géométrie analytique, analyse, etc. Elle ne cessite des raisonnements sur des fonctions dont on ne connaît pas l'expression symbolique. Les efforts actuels pour changer le paradigme algébriqu dominant font appel aux outils informatiques. Or, des logiciels comme Cabri Géomètre permettent de créer des contextes d'exploration de phénomène~ graphiques liés aux équations différentielles. Nous étudions ici les difficultés des étudiants de CAPES pour construire des liens entre les registres graphique et symbolique, ainsi que les apports du logiciel pour développer ces liens. Au chapitre 1, nous passons en revue quelques travaux de référence. A l'aide de certains outils théoriques, nous clarifions la problématique pour articuler ces registres. Puis, nous étudions les potentialités du logiciel pour l'étude des équations différentielles. Au chapitre 2, nous présentons le dispositif expérimental conçu pour vérifier nos hypothèses. Nous dédions ensuite deux chapitres à l'étude des expériences réalisées. Au chapitre 5, nous tirons un bilan de ces expériences et nous montrons les difficultés rencontrées par les étudiants, ainsi que les apports du logiciel. En conclusion nous revenons sur les questions initiales, et sur les éléments de réponse et les perspectives de notre travail.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Evaluación de un cebo feromonal para la captura del picudo del agave (Coleoptera: Curculionidae)

The agave weevil, Scyphophorus acupunctatus Gyllenhal, is considered the most important insect pest of the cultivated agaves in Mexico. Recent studies on the chemical ecology of this weevil have shown that males release a pheromone that attracts both sexes; the pheromone is composed of four components. Previous field experiments showed that all components, singled or in blends, were attractive to the weevils, but compounds 2-methyl-4-heptanone (C1) and 2-methyl-4-octanone (C2) were sufficient to obtain captures equivalent to those by the quaternary blend. In this study, we investigated the effect of different ratios (1:1, 1:2, 1:4, 2:1, and 4:1) and doses (50, 100, 150, 200, 350, and 500 mg)of C1 and C2 in the captures of the agave weevils in commercial plantations of Agave tequilana Weber. Our results showed that traps baited with synthetic pheromone captured more weevils than traps baited with adult male weevils but the different ratios of C1 and C2 did not affect the weevils capture. In fact, traps baited with C2 caught more weevils than those baited with the binary blend. Also, we found that weevil’s capture was not affected by dose. In general, traps baited with the synthetic pheromonal components caught more females than males. El picudo del agave, Scyphophorus acupunctatus Gyllenhal, es una plaga de importancia económica en diferentes cultivos de agaves en México, principalmente en agave tequilero, agave mezcalero y henequén. Los machos de esta especie liberan una feromona de agregación que atrae a ambos sexos, la feromona esta compuesta por dos alcoholes y dos cetonas. Experimentos previos han mostradoque los cuatro compuestos son atractivos a los picudos del agave, pero las mayores capturas se obtuvieron cuando se combinaron la 2-metil-4-heptanona (C1) y la 2-metil-4-octanona (C2). En el presente estudio se realizaron experimentos en campo para evaluar el efecto de las proporciones (1:1, 1:2, 1:4, 2:1 y 4:1) y la dosis (50, 100, 150, 200, 350, y 500 mg) de C1 y C2 en la captura de los picudos. Los resultados muestran que las diferentes proporciones probadas de los dos componentes feromonales no afectaron las capturas de los insectos. De hecho las trampas cebadas con C2 tuvieron mayores capturas que trampas cebadas con la combinación de los dos compuestos. Con respecto al otro factor evaluado,nuestros resultados muestran que la dosis no afectó las capturas de trampas cebadas con la feromona. Las trampas cebadas con los compuestos feromonales sintéticos capturaron más hembras que machos