University of Rouen

About: University of Rouen is a education organization based out in Rouen, France. It is known for research contribution in the topics: Population & Receptor. The organization has 7299 authors who have published 13209 publications receiving 313477 citations.

Influence of Hyperparameters on Random Forest Accuracy

Abstract: In this paper we present our work on the Random Forest (RF) family of classification methods. Our goal is to go one step further in the understanding of RF mechanisms by studying the parametrization of the reference algorithm Forest-RI. In this algorithm, a randomization principle is used during the tree induction process, that randomly selects K features at each node, among which the best split is chosen. The strength of randomization in the tree induction is thus led by the hyperparameter K which plays an important role for building accurate RF classifiers. We have decided to focus our experimental study on this hyperparameter and on its influence on classification accuracy. For that purpose, we have evaluated the Forest-RI algorithm on several machine learning problems and with different settings of K in order to understand the way it acts on RF performance. We show that default values of K traditionally used in the literature are globally near-optimal, except for some cases for which they are all significatively sub-optimal. Thus additional experiments have been led on those datasets, that highlight the crucial role played by feature relevancy in finding the optimal setting of K .

Efficacy of an educational and counseling intervention on adherence to highly active antiretroviral therapy: French prospective controlled study.

Abstract: Purpose: The objective was to evaluate the impact of an intervention for improving adherence to antiretroviral therapies (HAART) in HIV-infected patients. Method: We designed a prospective, controlled, randomized trial to assess the impact of an educational and counseling intervention in addition to standard of care. At M0, the study enrolled 244 HAART-treated patients who attended a medical consultation between September and December 1999 who were not included in another protocol. Patients in the intervention group (IG) were offered three individual sessions by trained nurses. The proportions of adherent patients at 6 months followup (M6) and the change in HIV RNA between M0 and M6 were measured. Results: Between M0 and M6, HIV RNA significantly decreased in the 123 patients of the IG (mean difference = –0.22 log [±0.86], p = .013), while it increased (+0.12 log [±0.90], p = .14) in the 121 patients of the control group. However, the proportion of patients with HIV RNA <40 copies/mL remained simi...

Incorporation of a Hydrophobic Antibacterial Peptide into Amphiphilic Polyelectrolyte Multilayers : A Bioinspired Approach to Prepare Biocidal Thin Coatings

Abstract: A non-water-soluble natural antibacterial peptide, gramicidin A, has been successfully incorporated into polyelectrolyte assemblies to elaborate biocidal thin films. For this, we used a double strategy, the first step of which consists of complexing the peptide by a non-denaturing anionic amphiphilic polysaccharide, namely a hydrophobically modified carboxymethylpullulan. We demonstrate that the use of this amphiphilic anionic derivative allows to efficiently solubilize the peptide in aqueous solution, without denaturation. The amount of peptide solubilized by the amphiphilic polysaccharide was optimized by systematically varying the hydrophobicity and the molar mass of the CMP derivative. In a second step, the negatively charged complex was layer-by-layer assembled with cationic poly(L-lysine) to form biofunctionalized thin films. The amount of peptide incorporated in the multilayers was controlled by changing the number of deposited complex layers, and was quantified by UV spectroscopy. The antibacterial activity of the resulting biofunctionalized films was I evidenced against a gram-positive bacterium, E. faecalis. We demonstrated that the biocidal activity resulted from a double mechanism: contact between bacteria and the film surface, and release of the peptide into the solution surrounding the film. We also showed that the peptide was not completely removed from the film after rinsing, which insured preservation of the biocidal activity of the film surface.

Diatom-Specific Oligosaccharide and Polysaccharide Structures Help to Unravel Biosynthetic Capabilities in Diatoms

Abstract: Diatoms are marine organisms that represent one of the most important sources of biomass in the ocean, accounting for about 40% of marine primary production, and in the biosphere, contributing up to 20% of global CO2 fixation. There has been a recent surge in developing the use of diatoms as a source of bioactive compounds in the food and cosmetic industries. In addition, the potential of diatoms such as Phaeodactylum tricornutum as cell factories for the production of biopharmaceuticals is currently under evaluation. These biotechnological applications require a comprehensive understanding of the sugar biosynthesis pathways that operate in diatoms. Here, we review diatom glycan and polysaccharide structures, thus revealing their sugar biosynthesis capabilities.