Développement d’un outil de segmentation des comportements d’achat des clients en se basant sur leurs données morphologiques

RÉSUMÉ : L’analyse des marchés commerciaux est actuellement un processus aussi bien scientifique qu’industriel. Il consiste à recueillir et explorer des informations reliées aux clients en vue de mieux comprendre leurs comportements, habitudes et intérêts. Cette analyse est fortement utilisée par les entreprises afin de les guider dans leurs décisions opérationnelles et stratégiques. Ce mémoire présente un des outils d’analyse des marchés les plus utilisés dans la littérature, qui est la segmentation. Cette approche vise à diviser un ensemble d’individus hétérogènes, en groupes plus homogènes, en se basant sur des critères prédéterminés. La segmentation des marchés est employée dans plusieurs domaines, et vise à diviser un ensemble de clients en plus petits groupes ayant des comportements similaires. Elle peut être employée pour l’amélioration de l’impact et des revenus des produits et services existants ou pour préparer l’introduction de nouveaux produits sur les marchés. Dans notre cas, la segmentation des clients est basée sur l’évolution de tailles des vêtements qu’ils commandent, ou ce qu’on appellera leurs données morphologiques. Les clients font leurs achats sur une plateforme d’achat en ligne fournie par notre partenaire industriel. Notre partenaire est une entreprise qui se charge de la sous-traitance des programmes d’uniformes pour ses clients. Dans ce travail, nous avons utilisé des méthodes de « data mining » pour analyser l’historique des données d’achat d’un des clients de notre partenaire pour une durée d’étude déterminée. Les analyses sont par la suite concentrées sur le type de vêtements le plus commandé, soit les chemises. Des séries chronologiques des tailles commandées pour chaque client sont construites. Ces séries chronologiques permettent d’étudier l’évolution des tailles dans le temps. La segmentation est par la suite appliquée sur ces séries chronologiques afin d’obtenir des groupes ayant des comportements similaires. La similarité entre les clients est basée sur une métrique appelée le Dynamic Time Warping. Cette distance a été choisie parce qu’elle est la plus adaptée pour comparer les séries temporelles en se basant sur leurs formes et en ne tenant pas compte du décalage sur l’axe temporel. Plusieurs tests basés sur différentes méthodes et algorithmes ont eu lieu. Aussi plusieurs structures et variantes des séries temporelles ont été testées. Les séries temporelles retenues sont des séries exprimées en fonction de la variation des mensurations dans le temps. Elles ont été normalisées avec la norme z. Deux segmentations avec des nombres de groupes égaux à six et à dix ont été réalisées. Finalement, une évaluation et une analyse des résultats de la segmentation ont été effectuées pour valider les résultats recueillis. En premier lieu, l’évaluation s’est basée sur la visualisation des groupes obtenus et sur le critère de silhouette. Ce critère permet de mesurer la qualité d’une segmentation donnée, en se basant sur l’homogénéité intragroupe et l’hétérogénéité inter-groupe. Nous avons trouvé que la segmentation en dix groupes a permis d’avoir de meilleurs groupes. Dans un second temps, pour chacun des cas, l’analyse des groupes nous a permis de comprendre la structure et les caractéristiques de ces derniers. Nous avons trouvé que la majorité des clients ont des courbes d’évolution croissante. Nous avons aussi constaté que les groupes ayant des courbes d’évolution stables, ont des pourcentages de retour relativement élevés par rapport à leurs pourcentages d’achat. La répartition des hommes et des femmes dans les groupes est semblable à celle du groupe de clients initial. Cependant, les groupes ayant un pourcentage de femme plus important que les autres ont des moyennes de tailles plus petites.----------ABSTRACT : The analysis of commercial markets is currently a scientific as well as an industrial process. It consists of collecting and exploring information related to clients in order to better understand their behaviours, habits and interests. This analysis is widely used by companies to guide them in their operational and strategic decisions. This paper presents one of the most widely used market analysis tools in the literature, namely segmentation. This approach aims to divide a set of heterogeneous individuals into more homogeneous groups, based on predetermined criteria. Market segmentation is used in several areas and aims to divide a set of customers into smaller groups with similar behaviors. It can be used to improve the impact and revenues of existing products and services or to prepare for the introduction of new products to markets. In our case, customer segmentation is based on the size evolution of the clothes they order, or what we will call their morphological data. Customers make their purchases on an online shopping platform provided by our partner. Our partner is a company that subcontracts uniform programs for its customers. In this work, we used data mining methods to analyze the purchase data history of one of our partner’s customers for a specific study period. The analyses are then focused on the most ordered type of clothing, namely shirts. Time series of the sizes ordered for each customer are built. These time series make it possible to study the evolution of sizes over time. Segmentation is then applied to these time series to obtain groups with similar behaviors. The similarity between customers is based on a metric called Dynamic Time Warping. This distance was chosen because it is the most suitable for comparing time series based on their shapes and ignoring the time axis offset. Several tests based on different methods and algorithms were carried out. Also, several structures and variants of the time series were tested. The time series used are series expressed as a function of the variation in measurements over time, and which were normalized with the z-norm. Two segmentations with numbers of groups equal to six and ten were performed. Finally, an evaluation and analysis of the segmentation results was carried out to validate the results collected. First, the evaluation was based on the visualization of the groups obtained and on the silhouette criterion. This criterion makes it possible to measure the quality of a given segmentation, based on intra-group homogeneity and inter-group heterogeneity. We found that the segmentation into ten groups allowed us to have better groups. This segmentation improved the silhouette index obtained with six groups. In a second step, for each case, the analysis of the groups allowed us to understand their structure and characteristics. We found that most clients have increasing trend curves. We also found that groups with stable evolution curves have relatively high return rates compared to their purchase rates. The distribution of men and women in the groups is similar to that of the original client group. However, groups with a higher percentage of women were found to have smaller average sizes

Bot IT2: a new scorpion toxin to study receptor site on insect sodium channels

AbstractThe insect-specific Bothus occitanus tunetanus IT2 toxin is distinguishable from other scorpion toxins by its amino acid sequence and effects on sodium conductance. The present study reveals that Bot IT2 possesses in cockroach neuronal membranes a single class of high affinity (Kd=0.3±0.1 nM) and low capacity (Bmax=2.4±0.5 pmol/mg) binding sites. Competitive binding experiments with several known sodium channel neurotoxins reveal that the Bot IT2 binding site is in close proximity to the other toxins.© 1997 Federation of European Biochemical Societies

Snake Venom Peptides: Promising Molecules with Anti-Tumor Effects

International audienc

The application of multiplex fluorimetric sensor for the analysis of flavonoids content in the medicinal herbs family Asteraceae, Lamiaceae, Rosaceae

BACKGROUND: The aim of our research work was to quantify total flavonoid contents in the leaves of 13 plant species family Asteraceae, 8 representatives of family Lamiaceae and 9 plant species belonging to familyRosaceae, using the multiplex fluorimetric sensor. Fluorescence was measured using optical fluorescence apparatus Multiplex(R) 3 (Force-A, France) for non-destructive flavonoids estimation. The content of total flavonoids was estimated by FLAV index (expressed in relative units), that is deduced from flavonoids UV absorbing properties. RESULTS: Among observed plant species, the highest amount of total flavonoids has been found in leaves ofHelianthus multiflorus (1.65 RU) and Echinops ritro (1.27 RU), Rudbeckia fulgida (1.13 RU) belonging to the family Asteraceae. Lowest flavonoid content has been observed in the leaves of marigold (Calendula officinalis) (0.14 RU) also belonging to family Asteraceae. The highest content of flavonoids among experimental plants of family Rosaceae has been estimated in the leaves of Rosa canina (1.18 RU) and among plant species of family Lamiaceae in the leaves of Coleus blumei (0.90 RU). CONCLUSIONS: This research work was done as pre-screening of flavonoids content in the leaves of plant species belonging to family Asteraceae, Lamiaceae and Rosaceae. Results indicated that statistically significant differences (P > 0.05) in flavonoids content were observed not only between families, but also among individual plant species within one family

MVL-PLA2, a Snake Venom Phospholipase A2, Inhibits Angiogenesis through an Increase in Microtubule Dynamics and Disorganization of Focal Adhesions

Integrins are essential protagonists of the complex multi-step process of angiogenesis that has now become a major target for the development of anticancer therapies. We recently reported and characterized that MVL-PLA2, a novel phospholipase A2 from Macrovipera lebetina venom, exhibited anti-integrin activity. In this study, we show that MVL-PLA2 also displays potent anti-angiogenic properties. This phospholipase A2 inhibited adhesion and migration of human microvascular-endothelial cells (HMEC-1) in a dose-dependent manner without being cytotoxic. Using Matrigel™ and chick chorioallantoic membrane assays, we demonstrated that MVL-PLA2, as well as its catalytically inactivated form, significantly inhibited angiogenesis both in vitro and in vivo. We have also found that the actin cytoskeleton and the distribution of αvβ3 integrin, a critical regulator of angiogenesis and a major component of focal adhesions, were disturbed after MVL-PLA2 treatment. In order to further investigate the mechanism of action of this protein on endothelial cells, we analyzed the dynamic instability behavior of microtubules in living endothelial cells. Interestingly, we showed that MVL-PLA2 significantly increased microtubule dynamicity in HMEC-1 cells by 40%. We propose that the enhancement of microtubule dynamics may explain the alterations in the formation of focal adhesions, leading to inhibition of cell adhesion and migration

Modulation of Kv3.1b potassium channel level and intracellular potassium concentration in 158N murine oligodendrocytes and BV-2 murine microglial cells treated with 7-ketocholesterol, 24S-hydroxycholesterol or tetracosanoic acid (C24:0)

International audienceLittle is known about K+ regulation playing major roles in the propagation of nerve impulses, as well as in apoptosis and inflammasome activation involved in neurodegeneration. As increased levels of 7-ketocholesterol (7KC), 24S-hydroxycholesterol (24S-OHC) and tetracosanoic acid (C24:0) have been observed in patients with neurodegenerative diseases, we studied the effect of 24 and/or 48 h of treatment with 7KC, 24S-OHC and C24:0 on Kv3.1b potassium channel level, intracellular K+ concentration, oxidative stress, mitochondrial dysfunction, and plasma membrane permeability in 158N oligodendrocytes and BV-2 microglial cells. In 158N cells, whereas increased level of Kv3.1b was only observed with 7KC and 24S-OHC but not with C24:0 at 24 h, an intracellular accumulation of K+ was always detected. In BV-2 cells treated with 7KC, 24S-OHC and C24:0, Kv3.1b level was only increased at 48 h; intracellular K+ accumulation was found at 24 h with 7KC, 24S-OHC and C24:0, and only with C24:0 at 48 h. Positive correlations between Kv3.1b level and intracellular K+ concentration were observed in 158N cells in the presence of 7KC and 24S-OHC, and in 7KC-treated BV-2 cells at 48 h. Positive correlations were also found between Kv3.1b or the intracellular K+ concentration, overproduction of reactive oxygen species, loss of transmembrane mitochondrial potential and increased plasma membrane permeability in 158N and BV-2 cells. Our data support that the lipid environment affects Kv3.1b channel expression and/or functionality, and that the subsequent rupture of K+ homeostasis is relied with oligodendrocytes and microglial cells damages