DTLS Performance in Duty-Cycled Networks

The Datagram Transport Layer Security (DTLS) protocol is the IETF standard for securing the Internet of Things. The Constrained Application Protocol, ZigBee IP, and Lightweight Machine-to-Machine (LWM2M) mandate its use for securing application traffic. There has been much debate in both the standardization and research communities on the applicability of DTLS to constrained environments. The main concerns are the communication overhead and latency of the DTLS handshake, and the memory footprint of a DTLS implementation. This paper provides a thorough performance evaluation of DTLS in different duty-cycled networks through real-world experimentation, emulation and analysis. In particular, we measure the duration of the DTLS handshake when using three duty cycling link-layer protocols: preamble-sampling, the IEEE 802.15.4 beacon-enabled mode and the IEEE 802.15.4e Time Slotted Channel Hopping mode. The reported results demonstrate surprisingly poor performance of DTLS in radio duty-cycled networks. Because a DTLS client and a server exchange more than 10 signaling packets, the DTLS handshake takes between a handful of seconds and several tens of seconds, with similar results for different duty cycling protocols. Moreover, because of their limited memory, typical constrained nodes can only maintain 3-5 simultaneous DTLS sessions, which highlights the need for using DTLS parsimoniously.Comment: International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC - 2015), IEEE, IEEE, 2015, http://pimrc2015.eee.hku.hk/index.htm

Topology Construction in RPL Networks over Beacon-Enabled 802.15.4

In this paper, we propose a new scheme that allows coupling beacon-enabled IEEE 802.15.4 with the RPL routing protocol while keeping full compliance with both standards. We provide a means for RPL to pass the routing information to Layer 2 before the 802.15.4 topology is created by encapsulating RPL DIO messages in beacon frames. The scheme takes advantage of 802.15.4 command frames to solicit RPL DIO messages. The effect of the command frames is to reset the Trickle timer that governs sending DIO messages. We provide a detailed analysis of the overhead incurred by the proposed scheme to understand topology construction costs. We have evaluated the scheme using Contiki and the instruction-level Cooja simulator and compared our results against the most common scheme used for dissemination of the upper-layer information in beacon-enabled PANs. The results show energy savings during the topology construction phase and in the steady state

From text saliency to linguistic objects: learning linguistic interpretable markers with a multi-channels convolutional architecture

A lot of effort is currently made to provide methods to analyze and understand deep neural network impressive performances for tasks such as image or text classification. These methods are mainly based on visualizing the important input features taken into account by the network to build a decision. However these techniques, let us cite LIME, SHAP, Grad-CAM, or TDS, require extra effort to interpret the visualization with respect to expert knowledge. In this paper, we propose a novel approach to inspect the hidden layers of a fitted CNN in order to extract interpretable linguistic objects from texts exploiting classification process. In particular, we detail a weighted extension of the Text Deconvolution Saliency (wTDS) measure which can be used to highlight the relevant features used by the CNN to perform the classification task. We empirically demonstrate the efficiency of our approach on corpora from two different languages: English and French. On all datasets, wTDS automatically encodes complex linguistic objects based on co-occurrences and possibly on grammatical and syntax analysis.Comment: 7 pages, 22 figure

Objectiver l'intertexte ? Emmanuel Macron, deep learning et statistique textuelle

International audienceThe present paper suggests that intertextuality can be brought out objectively by resorting to specific methodological tools. The case in point is political intertextuality in the speeches of the French president Emmanuel Macron. Deep learning (convolutional model) is first used to "learn" (satisfactory accuracy rate of 92.3%) the French presidential speeches since 1958: the speeches of De Gaulle, Pompidou, Giscard, Mitterrand, Chirac, Sarkozy and Hollande are then considered as the potential intertext of Macron's own speeches. Next, Macron's texts-hitherto unknown to the machine-are included in the model and the machine is instructed to assign Macron's quotations to one of his predecessors based on their linguistic content. Finally, the algorithm extracts and describes Macron's quotations and linguistic units (wTDS, lexical specificities, co-occurrences, morpho-syntactic labels) as they were interpreted by the machine in comparison to those of De Gaulle or Sarkozy, of Mitterrand or Holland. Macron's discourse is permeated with, sometimes explicitly but more often than not implicitly, by the discourse of former French presidents-a phenomenon that we shall refer to as "intertextuality"-and it turns out that Artificial Intelligence and textual statistics are able to identify such phenomena of borrowing, imitation and even plagiarism.Cette contribution propose un parcours méthodologique susceptible d’objectiver l’intertexte ; l’intertexte politique des discours du président français Emmanuel Macron en l’occurrence.Le deep learning (modèle convolutionnel) est d’abord utilisé pour « apprendre » (taux d’accuracy satisfaisant de 92,3%) le discours présidentiel français depuis 1958 : les discours de de Gaulle, Pompidou, Giscard, Mitterrand, Chirac, Sarkozy et Hollande sont alors considérés comme l’intertexte potentiel des discours de Macron.Ensuite, les textes de Macron – inconnus jusqu’ici du système – sont versés dans le modèle et nous forçons la machine à attribuer les passages de Macron à l’un de ses prédécesseurs en fonction de leur composition linguistique. Enfin, l’algorithme extrait et décrit les passages et les unités linguistiques (wTDS, spécificités lexicales, cooccurrences, étiquettes morpho-syntaxiques) de Macron interprétées par la machine comme ressemblant à celles de de Gaulle ou Sarkozy, à celles de Mitterrand ou de Hollande.Le discours de Macron est traversé, de manière explicite parfois, de manière implicite le plus souvent, par les discours de ses prédécesseurs – phénomène que l’on appellera « intertextualité » – et l’Intelligence artificielle et la statistique textuelle peuvent repérer les phénomènes d’emprunt, d’imitation voire de plagiat

Machine Learning under the light of Phraseology expertise: use case of presidential speeches, De Gaulle -Hollande (1958-2016)

International audienceAuthor identification and text genesis have always been a hot topic for the statistical analysis of textual data community. Recent advances in machine learning have seen the emergence of machines competing state-of-the-art computational linguistic methods on specific natural language processing tasks (part-of-speech tagging, chunking and parsing, etc). In particular, Deep Linguistic Architectures are based on the knowledge of language speci-ficities such as grammar or semantic structure. These models are considered as the most competitive thanks to their assumed ability to capture syntax. However if those methods have proven their efficiency, their underlying mechanisms, both from a theoretical and an empirical analysis point of view, remains hard both to explicit and to maintain stable, which restricts their area of applications. Our work is enlightening mechanisms involved in deep architectures when applied to Natural Language Processing (NLP) tasks. The Query-By-Dropout-Committee (QBDC) algorithm is an active learning technique we have designed for deep architectures: it selects iteratively the most relevant samples to be added to the training set so that the model is improved the most when built from the new training set. However in this article, we do not go into details of the QBDC algorithm-as it has already been studied in the original QBDC article-but we rather confront the relevance of the sentences chosen by our active strategy to state of the art phraseology techniques. We have thus conducted experiments on the presidential discourses from presidents C. De Gaulle, N. Sarkozy and F. Hollande in order to exhibit the interest of our active deep learning method in terms of discourse author identification and to analyze the extracted linguistic patterns by our artificial approach compared to standard phraseology techniques.L'identification de l'auteur et la gen ese d'un texte ont toujours eté une question de tr es grand intérêt pour la com-munauté de l'analyse statistique des données textuelles. Les récentes avancées dans le domaine de l'apprentissage machine ont permis l'´ emergence d'algorithmes concurrençant les méthodes de linguistique computationnelles de l'´ etat de l'art pour des tâches spécifiques en traitement automatique du langage (´ etiquetage des parties du dis-cours, segmentation et l'analyse du texte, etc). En particulier, les architectures profondes pour la linguistique sont fondées sur la connaissance des spécificités linguistiques telles que la grammaire ou la structure sémantique. Ces mod eles sont considérés comme les plus compétitifs grâcè a leur capacité supposée de capturer la syntaxe. Toute-fois, si ces méthodes ont prouvé leur efficacité, leurs mécanismes sous-jacents, tant du point de vue théorique que du point de vue de l'analyse empirique, restent difficilè a la fois a expliciter et a maintenir stables, ce qui limite leur domaine d'application. Notre article visè a mettre enlumì ere certains des mécanismes impliqués dans l'apprentissage profond lorsqu'il est appliqué a des tâches de traitement automatique du langage (TAL). L'algorithme Query-By-Dropout-Committee (QBDC) est une technique d'apprentissage actif, nous avons conçu pour les architectures profondes : il sélectionne itérativement les echantillons les plus pertinents pour etre ajoutés a l'ensemble d'entrainement afin que le mod ele soit amélioré de façon optimale lorsqu'on il est mis a jour a partir du nouvel ensemble d'entrainement. Cependant, dans cet article, nous ne détaillons pas l'algorithme QBDC-qui a déj a ´ eté etudié dans l'article original sur QBDC-mais nous confrontons plutôt la pertinence des phrases choisies par notre stratégie active aux techniques de l'´ etat de l'art en phraséologie. Nous avons donc mené des expériences sur les discours présidentiels des présidents C. De Gaulle , N. Sarkozy et F. Hollande afin de présenter l' intérêt de notre méthode d'apprentissage profond actif en termes de d'identification de l'auteur d'un discours et pour analyser les motifs linguistiques extraits par notre approche artificielle par rapport aux techniques de phraséologie standard

Ces mots que Macron emprunte à Sarkozy. Discours et intelligence artificielle

La logométrie et l’Intelligence artificielle (deep learning) appliquées aux textes politiques permettent de repérer dans le discours d’Emmanuel Macron les emprunts linguistiques qu’il contracte auprès de ses prédécesseurs à l’Elysée (de Gaulle, Pompidou, Giscard, Mitterrand, Chirac, Sarkozy et Hollande). Les emprunts les plus importants, lexicaux autour de la valeur travail et énonciatifs autour de l’exhibition du « je » et du « je veux », concernent statistiquement Nicolas Sarkozy.Logometry and Artificial Intelligence (deep learning) applied to political texts make it possible to identify in Emmanuel Macron's speeches the linguistic borrowings he contracted from his predecessors at the Palais de l’Elysée (de Gaulle, Pompidou, Giscard, Mitterrand, Chirac, Sarkozy and Hollande). The most important borrowings, which are around the work value and enunciative around the exhibition of “I” and "I want", are statistically related to Nicolas Sarkozy

DTLS Performance in Duty-Cycled Networks

International audienceThe Datagram Transport Layer Security (DTLS) protocol is the IETF standard for securing the Internet of Things. The Constrained Application Protocol, ZigBee IP, and Lightweight Machine-to-Machine (LWM2M) mandate its use for securing application traffic. There has been much debate in both the standardization and research communities on the applicability of DTLS to constrained environments. The main concerns are the communication overhead and latency of the DTLS handshake, and the memory footprint of a DTLS implementation. This paper provides a thorough performance evaluation of DTLS in different duty-cycled networks through real-world experimentation, emulation and analysis. In particular, we measure the duration of the DTLS handshake when using three duty cycling link-layer protocols: preamble-sampling, the IEEE 802.15.4 beacon-enabled mode and the IEEE 802.15.4e Time Slotted Channel Hopping mode. The reported results demonstrate surprisingly poor performance of DTLS in radio duty-cycled networks. Because a DTLS client and a server exchange more than 10 signaling packets, the DTLS handshake takes between a handful of seconds and several tens of seconds, with similar results for different duty cycling protocols. Moreover, because of their limited memory, typical constrained nodes can only maintain 3-5 simultaneous DTLS sessions, which highlights the need for using DTLS parsimoniously

From text saliency to linguistic objects: learning linguistic interpretable markers with a multi-channels convolutional architecture

A lot of effort is currently made to provide methods to analyze and understand deep neural network impressive performances for tasks such as image or text classification. These methods are mainly based on visualizing the important input features taken into account by the network to build a decision. However these techniques, let us cite LIME, SHAP, Grad-CAM, or TDS, require extra effort to interpret the visualization with respect to expert knowledge. In this paper, we propose a novel approach to inspect the hidden layers of a fitted CNN in order to extract interpretable linguistic objects from texts exploiting classification process. In particular, we detail a weighted extension of the Text Deconvolution Saliency (wTDS) measure which can be used to highlight the relevant features used by the CNN to perform the classification task. We empirically demonstrate the efficiency of our approach on corpora from two different languages: English and French. On all datasets, wTDS automatically encodes complex linguistic objects based on co-occurrences and possibly on grammatical and syntax analysis

Hyperdeep : deep learning descriptif pour l'analyse de données textuelles

International audienceSince few years, some tools that are helping us to interpret results of deep learning have appeared (LIME, LSTMVIS, TDS). In this paper, we propose to go further by searching hidden information encoded in intermediate layers of deep learning thanks to a new tool. Hyperdeep allows, on the one hand, to predict the belonging of a text and to appreciate its borrowings from different styles or authors and, on the other hand, it allows to analyze, by deconvolution, the spatial and static patterns of the text in order to bring up the linguistic markers learned by the network. This new type of linguistic objects is gathered and highlighted in a graphical tool combining visualizations and hypertext. This tool is fully integrated in the Hyperbase Web platform, which offers the adequate environment and a natural starting point for any study mixing deep learning and text mining. Abstract 2 (in French) Depuis peu, les outils d'aide à l'interprétation des résultats du deep learning font leur apparition (LIME, LSTMVIS, TDS). Dans cette communication nous proposons d'aller plus loin en allant chercher l'information cachée au plus profond des couches intermédiaires du deep learning grâce à un nouvel outil. Hyperdeep permet d'une part de prédire l'appartenance d'un texte et d'en apprécier les emprunts à différents styles ou auteurs et d'autre part, par déconvolution, d'analyser les motifs spatiaux et statiques du texte afin d'en faire remonter les marqueurs linguistiques appris par le réseau. Cette information d'un genre nouveau est rassemblée et mise en valeur dans un nouvel outil mêlant visualisations graphiques et texte dynamique. Son utilisation est accompagnée d'une intégration complète dans la plateforme Hyperbase Web qui propose l'environnement adéquate et un point de départ naturel pour toute étude mêlant deep learning et statistiques du texte.Depuis peu, les outils d'aide à l'interprétation des résultats du deep learning font leur apparition (LIME, LSTMVIS, TDS). Dans cette communication nous proposons d'aller plus loin en allant chercher l'information cachée au plus profond des couches intermédiaires du deep learning grâce à un nouvel outil. Hyperdeep permet d'une part de prédire l’appartenance d’un texte et d’en apprécier les emprunts à différents styles ou auteurs et d’autre part, par déconvolution, d'analyser les saillances du texte afin d’en faire remonter les marqueurs linguistiques appris par le réseau. Cette information d’un genre nouveau est rassemblée et mise en valeur dans un nouvel outil mêlant visualisations graphiques et texte dynamique. Son utilisation est accompagnée d’une intégration complète dans la plateforme Hyperbase Web qui propose l’environnement adéquate et un point de départ naturel pour toute étude mêlant deep learning et statistiques du texte

Dietary Cholesterol-Induced Post-Testicular Infertility

This work shows that an overload of dietary cholesterol causes complete infertility in dyslipidemic male mice (the Liver X Receptor-deficient mouse model). Infertility resulted from post-testicular defects affecting the fertilizing potential of spermatozoa. Spermatozoa of cholesterol-fed lxr−/− animals were found to be dramatically less viable and motile, and highly susceptible to undergo a premature acrosome reaction. We also provide evidence, that this lipid-induced infertility is associated with the accelerated appearance of a highly regionalized epididymal phenotype in segments 1 and 2 of the caput epididymidis that was otherwise only observed in aged LXR-deficient males. The epididymal epithelial phenotype is characterized by peritubular accumulation of cholesteryl ester lipid droplets in smooth muscle cells lining the epididymal duct, leading to their transdifferentiation into foam cells that eventually migrate through the duct wall, a situation that resembles the inflammatory atherosclerotic process. These findings establish the high level of susceptibility of epididymal sperm maturation to dietary cholesterol overload and could partly explain reproductive failures encountered by young dyslipidemic men as well as ageing males wishing to reproduce