Unconfused Ultraconservative Multiclass Algorithms

We tackle the problem of learning linear classifiers from noisy datasets in a multiclass setting. The two-class version of this problem was studied a few years ago by, e.g. Bylander (1994) and Blum et al. (1996): in these contributions, the proposed approaches to fight the noise revolve around a Perceptron learning scheme fed with peculiar examples computed through a weighted average of points from the noisy training set. We propose to build upon these approaches and we introduce a new algorithm called UMA (for Unconfused Multiclass additive Algorithm) which may be seen as a generalization to the multiclass setting of the previous approaches. In order to characterize the noise we use the confusion matrix as a multiclass extension of the classification noise studied in the aforementioned literature. Theoretically well-founded, UMA furthermore displays very good empirical noise robustness, as evidenced by numerical simulations conducted on both synthetic and real data. Keywords: Multiclass classification, Perceptron, Noisy labels, Confusion MatrixComment: ACML, Australia (2013

From Cutting Planes Algorithms to Compression Schemes and Active Learning

Cutting-plane methods are well-studied localization(and optimization) algorithms. We show that they provide a natural framework to perform machinelearning ---and not just to solve optimization problems posed by machinelearning--- in addition to their intended optimization use. In particular, theyallow one to learn sparse classifiers and provide good compression schemes.Moreover, we show that very little effort is required to turn them intoeffective active learning methods. This last property provides a generic way todesign a whole family of active learning algorithms from existing passivemethods. We present numerical simulations testifying of the relevance ofcutting-plane methods for passive and active learning tasks.Comment: IJCNN 2015, Jul 2015, Killarney, Ireland. 2015, \<http://www.ijcnn.org/\&g

Collective beliefs for responsible investment

International audienceThe financial community does not seem to have shifted yet to greater sustainability, despite increasing awareness and concerns around social and environmental issues. In this paper, we provide insights to help understand why. Building on responsible investment (RI) data from the UK financial press between 1982 and 2010, we examine the collective beliefs which financial actors rely on to take decisions under uncertainty, as a way of understanding the status of and implications for RI mainstreaming. Our results identify five periods that characterize RI over time. The “civil rights” years (1982-1991), the “green niche” years (1992-1997), the “professionalization” years (1998-2000), the “SRI” years (2001-2004) and the “ESG” years (2005-ongoing) follow each other with specific representations and practices for RI. The analysis of the collective beliefs leads us to define two theoretical dimensions – justifying RI and practicing RI—that allow us to characterize how mainstream actors collectively make sense of RI. Our data confirm the existence of collective beliefs around RI and highlights changes in the content of the collective beliefs throughout the five periods, demonstrating a dynamic in the RI field. Our analysis reveals that the RI collective beliefs currently (1) do not provide a favorable environment for RI mainstreaming and (2) need to be taken into account when discussing the value of sustainability

Détermination de la structure tectonique de l'aquifère crayeux du littoral Nord Pas-de-Calais par prospection géophysique couplée à des observations par forage. Conséquence sur la répartition d'eau salée

Sur le littoral du Nord - Pas-de-Calais (France), la Craie d'âge Crétacé supérieur constitue l'aquifère le plus exploité régionalement pour l'alimentation en eau tant potable qu'industrielle. Sur la frange la plus littorale, l'aquifère crayeux, semi-captif est affecté par de nombreuses failles. Dans certains secteurs, la profondeur de la craie et la localisation des failles, restent aléatoires suite au manque de forages et d'affleurements. Afin de palier à ces lacunes, trois méthodes géophysiques (sondages électriques et sismiques, profilage électromagnétique) ont été appliquées.La synthèse des données obtenues a permis de démontrer que la craie est découpée en une série de compartiments par des accidents tectoniques présentant un affaissement vers le Sud et vers l'Ouest. L'interprétation des données géophysiques a également permis d'obtenir des informations sur la répartition de l'interface eau douce - eau salée au sein de l'aquifère crayeux.Dans la région, le concept classique de biseau salé ne permet pas d'expliquer l'irrégularité spatiale des intrusions. L'étude semble démontrer que la répartition et l'extension des intrusions d'eau salée peuvent être corrélées avec la localisation des accidents tectoniques, les intrusions les plus éloignées du rivage se faisant au droit des zones faillées.Ceci amène à proposer une nouvelle approche concernant l'extension des intrusions d'eau salée : elles seraient directement tributaires de la géométrie et des caractéristiques hydrodynamiques de l'aquifère crayeux, ces dernières étant fortement influencées par la présence des failles.Along the North Pas-de-Calais coast between a point south of Boutonnière du Boulonnais and the Authie River, Cretaceous rocks are limited to the east by a paleocliff that overlooks the Quaternary coastal and dune deposits. The chalk aquifer is connected to the Quaternary aquifers and further west to the sea water. Close to the seashore the top of the chalk plateau falls rapidly from 20 m above sea level to 20 m below sea level, causing the aquifer to grade from being unconfined in the east to confined in the west. This chalky aquifer is cut by several faults. A structural survey (LOUCHE et al., 1997) based on borehole data was carried out to evaluate whether the rate and direction of groundwater flow are controlled by the different faults. Two major fault groups striking N030° and N110° have been revealed by the structural map, with a third minor group (N 160- 170°) to the north of the Canche. The two major groups, created during tectonic activity from the Palaeozoic to the present, are composed respectively of structures with general faulting directions of N 100-110° and N 020-040°, previously described by COLBEAUX et al. (1993). Chalk depth and fault location are unknown in certain areas due to the lack of bore holes and outcrops. With the aim of overcoming these deficiencies, three traditional geophysical techniques (electrical sounding, seismic logging and electromagnetic profiling) were carried out between the Canche and Authie rivers in the coastal area, west of the chalky cliffs.The interpretation of the geophysical results allows us to confirm the presence of previously located faults and identify new ones in the area where the chalk is overlain by Quaternary cover. The chalky aquifer is hence divided by the faults into a series of compartments that are inclined to the south or to the west. In addition, anomalies have been recorded in the fresh water - salt water interface on the Picardy continental shelf (MERCIER & BACROT, 1990). These anomalous zones are aligned along the northern extension of the sub N-S faults proposed by MENNESSIER & BEUN (1980), located a few kilometres to the south. Based on indirect evidence, these latter authors interpreted these faults as being responsible for considerable displacement of a major part of the Quaternary deposits. Given the lack of direct observations on salt-water distribution, geophysical results, and more specifically the electrical soundings, are required to provide supplementary information in order to better understand this phenomenon. Furthermore, the study of the salt water location, using electrical soundings, points out the juxtaposition of deep saline intrusions, demonstrating that the concept of a homogeneous wedge-shaped body parallel to the seashore can no longer be used to describe this chalky aquifer.In the Bas-Champs area, electromagnetic profiling and three electrical soundings provided additional information on the relation between tectonic events and saline water intrusion (Fig. 3). The electromagnetic profiling shows the presence of two faults (Fig. 6). The vertical faults have an apparent low electrical resistivity (2.5 Ω.m) indicating the presence of brackish or salt water. Electrical sounding carried out to the south of the electromagnetic profile (SE9) shows a decrease in the electrical resistivity from 12.5 m depth, also confirming the presence of salt water. The results of an electrical sounding located to the north of the electromagnetic profile (SE10) show that the ground is saturated with fresh water up to at least 27.2 m (resistivity of 90 Ω.m). At 1 km distance, there is a juxtaposition of three sectors separated by faults filled up with salt water. However, an electrical sounding (SE2, Fig. 2) located near the sea showed that the ground is saturated with fresh water up to at least 52.7 m deep.Using geological, hydrogeological and geophysical data correlations, between structural context and saltwater intrusion could be established and a new hypothesis for saltwater intrusion for this study area could be proposed. Intrusion is directly dependent on the geometry and the hydrodynamic characteristics of the chalky aquifer, as reflected by its heterogeneous nature.Salt water seems to follow preferential intrusion directions corresponding to faults rather than the classic model of a salt wedge. These results suggest the hypothesis that the seawater intrusion distribution relates to the tectonic configuration of the aquifer. The chalky series is cut into hydrogeological compartments individualised by tectonic accidents, which are preferential axes for sea intrusion. The presence of a saltwater front located far from the coast, as indicated by electrical soundings, could be explained by the geological history of the maritime plain, where the Pleistocene and Holocene seas covered the maritime plain up to the fossil cliff (LOUCHE et al., 1998)

Heat Estimation from Infrared Measurement Compared to DSC for Austenite to R Phase Transformation in a NiTi Alloy

International audienceHeat sources estimations from temperature field measurements deduced from infrared imaging are increasingly used to study thermo-mechanical coupling during materials deformation. These estimations are based on approximations of the derivative terms with respect to time and space which are involved in the heat diffusion equation. This paper proposes a first experimental validation of this method by applying it to an experimental uniform air cooling of a NiTi Shape Memory Alloy thin plate. In the studied cooling temperate range, heat sources are due to Austenite to R phase transformation. Transformation temperatures, heat sources and energies are estimated from infrared temperature measurements and compared to differential scanning calorimetry results. The small 2 discrepancies are mainly explained by errors in DSC measurements due to thermal inertia and baseline determination

An original method to estimate local thermophysical properties and latent heat from Thermal Field Measurement (TFM)

International audienceThis paper presents an original method: (i) to estimate thermophysical properties (heat capacity C and thermal condictivity K) and (ii) to experimentally validate heat source estimations. The method, called Thermal Field Measurements (TFM), is based on infrared thermal observations during cooling experiments in a same experimental setup. Results obtained with this method are in good agreement with other resutls published in literature. Only the homogeneous case is presented in this paper but a 1D heterogeneous case will also be presented in the conference

Unpacking the drivers of corporate social performance: a multilevel, multistakeholder, and multimethod analysis

The question of what drives corporate social performance (CSP) has become a vital concern for many managers and researchers of large corporations. This study addresses this question by adopting a multilevel, multistakeholder, and multimethod approach to theorize and estimate the relative influence of macro (national business system and country), meso (industry), and micro (firm-level) factors on CSP. Applying three different methods of variance decomposition analysis to an international sample of 2,060 large public companies over a time span of 5 years, our results show that firm-level factors explain the largest proportion of variance in aggregate CSP as well as CSP oriented toward communities, the natural environment, and employees. These results support our hypotheses according to which CSP is not primarily driven by macrolevel or meso level factors, except for shareholder-oriented CSP, which is relatively more influenced by country-level factors. As a whole, our findings also point to the value of subdividing CSP into its stakeholder-specific components as this disaggregation allows for a more careful examination of distinct drivers of distinct aspects of CSP

The institutional and social construction of responsible investment

This paper provides a summary of the symposium on the institutional and social construction of Responsible Investment (RI), held at the 22nd IABS Conference. In the context of the symposium, we propose to move beyond the dominant focus on the financial impact of RI to consider the potential of emergent institutional and sociological perspectives to explain the practices and concepts related to RI. In doing so, our aim is to explore in greater detail the current changes in the RI infrastructure and the impact of these changes on wider issues of corporate sustainability and social responsibility