How to improve robustness in Kohonen maps and display additional information in Factorial Analysis: application to text mining

This article is an extended version of a paper presented in the WSOM'2012 conference [1]. We display a combination of factorial projections, SOM algorithm and graph techniques applied to a text mining problem. The corpus contains 8 medieval manuscripts which were used to teach arithmetic techniques to merchants. Among the techniques for Data Analysis, those used for Lexicometry (such as Factorial Analysis) highlight the discrepancies between manuscripts. The reason for this is that they focus on the deviation from the independence between words and manuscripts. Still, we also want to discover and characterize the common vocabulary among the whole corpus. Using the properties of stochastic Kohonen maps, which define neighborhood between inputs in a non-deterministic way, we highlight the words which seem to play a special role in the vocabulary. We call them fickle and use them to improve both Kohonen map robustness and significance of FCA visualization. Finally we use graph algorithmic to exploit this fickleness for classification of words

Christèle Couleau-Maixent, Balzac. Le roman de l’autorité. Un discours auctorial entre sérieux et ironie

À tous égards, l’ouvrage de Christèle Couleau-Maixent constitue une somme. Par l’ampleur du volume certes, mais également par la qualité des analyses, par la multiplicité des phénomènes abordés, par la manière enfin et surtout dont l’auteur rassemble un certain nombre d’avancées de la critique balzacienne de ces dernières années pour en proposer à la fois une synthèse et une réinterprétation globale. Depuis quinze ans en effet ont fleuri des études (articles ou thèses) de la poétique balzacie..

La « marche du progrès »

La métaphore de « la marche du progrès » commence à s’imposer en France à partir de 1830. Cette expression a des significations que l’article met en perspective : en elle se noue une représentation du temps et de l’humanité au confluent de l’histoire et de la science. L’émergence du modèle de la « marche du progrès » dans l’ordre des espèces coïncide avec l’idée d’une « marche du progrès » dans les sociétés humaines. Bien plus, cette métaphore regroupe plusieurs conceptions du progrès, ce qui a contribué à sa diffusion. L’image construit une représentation naturelle du progrès, sa redondance soulignant son inéluctabilité. Elle élabore également une représentation du progrès orientée vers une fin, ce qui laisse place à un nouveau providentialisme, qu’il soit historique ou scientifique.In France, the metaphor of “the march of progress” spreads from 1830. This image has different meanings that this article puts into perspective: it develops a representation of time and humanity at the confluence of history and science, as the emergence of a “march of progress” in natural species coincides with the idea of a “march of progress” in human societies. Moreover, this metaphor brings together several conceptions of progress, which has contributed to its dissemination. The image builds a natural representation of progress, the redundancy underlining its inevitability. It also develops a representation of progress towards an end, leading to a new providentialism in science and history

Peralkaline Felsic Magmatism of the Atlantic Islands

The oceanic-island magmatic systems of the Atlantic Ocean exhibit significant diversity in their respective sizes, ages, and the compositional ranges of their eruptive products. Nevertheless, almost all of the Atlantic islands and island groups have produced peralkaline felsic magmas, implying that similar petrogenetic regimes may be operating throughout the Atlantic Ocean, and arguably elsewhere. The origins of peralkaline magmas are frequently linked to low-degree partial melting of enriched mantle, followed by protracted differentiation in the shallow crust. However, additional petrogenetic processes such as magma mixing, crustal melting, and contamination have been identified at numerous peralkaline centers. The onset of peralkalinity leads to magma viscosities lower than those typical for metaluminous felsic magmas, which has profound implications for processes such as crystal settling. This study represents a compilation of published and original data which demonstrates trends that suggest that the peralkaline magmas of the Atlantic Ocean islands are generated primarily via extended (up to ∼ 95%), open system fractional crystallization of mantle-derived mafic magmas. Crustal assimilation is likely to become more significant as the system matures and fusible material accumulates in the crust. Magma mixing may occur between various compositional end-members and may be recognized via hybridized intermediate magmas. The peralkaline magmas are hydrous, and frequently zoned in composition, temperature, and/or water content. They are typically stored in shallow crustal magma reservoirs (∼ 2–5 km), maintained by mafic replenishment. Low melt viscosities (1 × 101.77 to 1 × 104.77 Pa s) facilitate two-phase flow, promoting the formation of alkali-feldspar crystal mush. This mush may then contribute melt to an overlying melt lens via filter pressing or partial melting. We utilize a three-stage model to account for the establishment, development, and termination of peralkaline magmatism in the ocean island magmatic systems of the Atlantic. We suggest that the overall control on peralkaline magmatism in the Atlantic is magma flux rate, which controls the stability of upper crustal magma reservoirs. The abundance of peralkaline magmas in the Atlantic suggests that their development must be a common, but not inevitable, stage in the evolution of ocean islands

Présentation du programme ArchAT (Université d'Orléans)

Ce mercredi 14 mars 2018, à l'occasion de la Journée des Lettres de l'Université d'Orléans, je présenterai le projet ArchAT en compagnie de Giorgia Vocino