Combinaison de prévisions hydrologiques globales et locales à l’aide de méthodes simples

L’augmentation exponentielle de la capacité de calcul, jumelée à la forte croissance de la disponibilité de données satellites des dernières décennies et à la collaboration des données scientifiques ont mené au récent développement d’un bon nombre de systèmes de prévisions hydrologiques large-échelle. Les prévisions produites par ces systèmes chevauchent souvent des régions déjà couvertes par des systèmes de prévisions hydrologiques locaux plus spécialisés. Cette recherche porte la possibilité d’obtenir de l’information des prévisions de ces systèmes large-échelle afin d’améliorer les prévisions locales. Plus précisément, les prévisions large-échelle du National Surface and River Prediction System (NSRPS) sont combinées aux prévisions hydrologiques locales du Système de Prévision Hydrologique (SPH) opéré par le Ministère de l’Environnement et de la Lutte aux changements climatiques (MELCCFP) à l’aide de méthodes simples dans le but d’optimiser les prévisions locales. La combinaison est effectuée à l’aide de plusieurs méthodes. Premièrement, une moyenne simple est utilisée en guise de référence de performance. Ensuite plusieurs variantes de moyennes pondérées sont utilisées, soit une première variante où les poids sont calculés analytiquement selon les résidus des modèles et trois autres variantes où les poids sont optimisés en utilisant comme fonction coût le Kling–Gupta Efficiency (KGE), le Reduced Continuous Ranked Probability Score (RCRPS) et le Ignorance Score (IGN). Le Bayesian Model Averaging est aussi utilisé afin de combiner les prévisions probabilistes des deux systèmes. Il s’agit d’une méthode plus élaborée qui utilisent comme poids les probabilités à posteriori d’un modèle à avoir généré les observations. Les résultats montrent clairement qu’une amélioration des prévisions hydrologiques locales est possible en utilisant des méthodes de combinaisons simples, et ce même si la performance du système de prévision local est drastiquement meilleure. L’évaluation de la performance des prévisions est effectuée selon de multiples critères afin de s’assurer que les résultats présentent un portrait juste et général de l’impact de la combinaison. Pour ce faire, les critères de Nash-Sutcliffe Efficiency (NSE), KGE, RCRPS et IGN sont utilisés. Les résultats sont moyennés sur 40 emplacements jaugés et analysées pour des horizons de prévision allant de 3 à 120 h. Pour toutes les méthodes autres que la moyenne simple, des gains en performance sont observés pour tous les critères pour des horizons de 60 h et plus et aucun critère ne révèle une perte de performance, peu importe l’horizon analysé. Enfin, l’effet de la combinaison des prévisions sur les bassins non-jaugés est analysé selon une simulation leave-one-out sur 29 bassins de validation. Des comportements très similaires aux bassins jaugés sont observés, suggérant que ces méthodes de combinaisons pourraient améliorer les prévisions hydrologiques des bassins des territoires plus éloignés et isolés, où aucune station de mesure n’est présente

Diagnosis and management of a full thickness macular hole

Background: First stage macular holes are not always easily identified without the use of medical imagery. Differential diagnosis from other macular conditions is possible with a keen eye and the use of a binocular fundus lens. However, the advent of optical coherence tomography facilitates accurate diagnosis. Case Report: This report demonstrates a classical case of a full thickness macular hole. The clinical signs are not pathognomonic at first, but typical signs develop in the following weeks. The different stages of the disease are described, as well as current state of surgical treatment and possible outcomes. Conclusions: Early diagnosis allows quick visual recovery. Nevertheless, this condition can be treated up to one year after occurrence with significant improvement of visual function

Wavefront Aberrations in Subjects Wearing Soft Aspheric Contact Lenses and Those Wearing Spherical Ones

Purpose: To measure the level of higher order aberrations (HOA) when wearing a soft aspheric contact lens (CL), compared to a spherical CL, in myopic subjects. Method: Fifteen myopic subjects aged 20-30 years were tested for the presence of dry eye. Aberrometry measurements were done without a contact lens as well as with a spherical CL and an aspheric CL. Root mean square error (RMS) of HOA, spherical aberration (SA) and coma were measured five times in an interval of 15 seconds without blinking for each of the 3 conditions. Results: Wearing a spherical CL produced a significant increase of SA and horizontal coma compared to an eye without a contact lens. When wearing an aspheric CL, there was a trend towards a smaller increase of these aberrations. However, the difference between both types of lens was not statistically significant. In terms of total HOA, these were higher when wearing the spherical CL, while they tended to be less with the aspheric CL. As for the variations between blinks, there was a similar increase in total HOA and individual modes with time for the three conditions. Conclusion : Wearers of aspheric CL seem to show a tendency towards smaller amounts of SA, horizontal coma and HOA in general in comparison with wearers of SCL. However, total HOA increases during a long interval between blinks, no matter the condition

Full-Field, Carrier-Less, Polarization-Diversity, Direct Detection Receiver based on Phase Retrieval

We realize dual-polarization full-field recovery using intensity only measurements and phase retrieval techniques based on dispersive elements. 30-Gbaud QPSK waveforms are transmitted over 520-km standard single-mode fiber and equalized from the receiver outputs using 2X2 MIMO

Identification du marqueur de cellules souches cancéreuses CD133 comme nouvelle cible de la MT1-MMP dans les cellules tumorales du cerveau

L'implication de la Membrane Type-Matrix Metalloproteinase (MT1-MMP) dans la progression du cancer a été grandement étudiée dans la dernière décennie. Elle possède une vaste variété de substrats, incluant des composants de la matrice extracellulaire, des cytokines et des récepteurs membranaires. Nos résultats identifient le marqueur de cellules souches (CSC) CD133 comme une nouvelle cible de l'activité protéolytique de la MT1-MMP. Des essais d'immunoprécipitation et de clivage in vitro effectués à l'aide de protéines recombinantes ont démontré que la MT1-MMP interagit physiquement avec CD133 et clive son domaine N-terminal à la position 30KAWN↓Y34. De plus, cette interaction semble commencer au niveau intracellulaire, dans le réticulum endoplasmique, avant l'activation de la proMT1-MMP et avant la maturation complète de CD133; toutefois, seulement la forme mature de CD133 peut être clivée. Ces résultats représentent la première interaction protéine-protéine connue de CD133, dont la fonction cellulaire demeure incomprise. Des expériences supplémentaires pourraient mener à une meilleure compréhension de cette protéine et de son rôle dans la biologie des CSCs. \ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : MT1-MMP, CSC, N-terminal, réticulum endoplasmiqu

Acting as a molecular tailor : dye structural modifications for improved sensitivity towards lysophosphatidic acids sensing

Lysophosphatidic acids (LPA) are key biomarkers for several physiological processes, the monitoring of which can provide insights into the host’s health. Common lab-based techniques for their detection are cumbersome, expensive and necessitate specialized personnel to operate. LPA-sensitive fluorescent probes have been described, albeit for non-aqueous conditions, which impedes their use in biological matrices. In this paper, we explore in detail the influence of structure on the extent of aggregation-induced fluorescence quenching using specially synthesized styrylpyridinium dyes bearing structural adaptations to bestow them enhanced affinity towards LPA in aqueous media. Spectroscopic investigations supported by time-resolved fluorimetry revealed the contribution of excimer formation to the fluorescence quenching mechanism displayed by the fluorescent probes. Experimental observations of the influence of structure on detection sensitivity were supported by DFT calculations

Disruptive mixed in vitro-in silico approach for protein engineering and screening

We present a strategy that combines wet-lab experimentation and computational protein design for engineering polypeptide chains. The protein sequences were numerically coded and then processed using Fourier Transform (FT). Fourier coefficients were used to calculate the energy spectra called protein spectrum . We use the protein spectrum to model the biological activity/fitness of protein from sequence data. We assume that the protein fitness (catalytic efficacy, thermostabilty, binding affinity, aggregation, stability…) is not purely local, but globally distributed over the linear sequence of the protein. Our patented method does not require any protein 3D structure information and find patterns that correlate with changes in protein activity (or fitness) upon amino acids residue substitutions. A minimal wet lab data sampled from mutation libraries (single or multiple points mutations) were used as learning data sets in heuristic approaches that were applied to build predictive models. We show the performance of the approach on designed libraries for 3 examples (enantioselectivity, thermostability and binding affinity) and discuss how our approach can tackle epistatic phenomena. We can screen up to 1 billion (109) protein variants in a very short time

Substantiating the influence of pore surface functionalities on the stability of grubbs catalyst in mesoporous SBA-15 silica

The influence of pore surface functionalities in mesoporous SBA‐15 silica on the stability of a model olefin metathesis catalyst, namely Grubbs I, is substantiated. In particular, it is demonstrated that the nature of the interaction between the ruthenium complex and the surface is strongly depending on the presence of surface silanols. For this study, differently functionalized mesoporous SBA‐15 silica materials were synthesized according to standard procedures and, subsequently, the Grubbs I catalyst was incorporated into these different host materials. All of the materials were thoroughly characterized by elemental analyses, nitrogen physisorption at −196 °C, thermogravimetric analyses, solid‐state NMR spectroscopy, and infrared spectroscopy (ATR‐IR). By such in‐depth characterization of the materials, it became possible to achieve models for the surface/catalyst interactions as a function of surface functionalities in SBA‐15; for example, in the case of purely siliceous silanol‐rich SBA‐15, octenyl‐silane modified SBA‐15, and silylated equivalents. It was evidenced that large portions of the chemisorbed species that are detected spectroscopically arise from interactions between the tricyclohexylphosphine and the surface silanols. A catalytic study using diethyldiallylmalonate in presence of the various functionalized silicas shows that the presence of surface silanols significantly decreases the longevity of the ring‐closing metathesis catalyst, whereas the passivation of the surface by trimethylsilyl groups slows down the catalysis rate, but does not affect significantly the lifetime of the catalyst. This contribution thus provides new insights into the functionalization of SBA‐15 materials and the role of surface interactions for the grafting of organometallic complexes

Innov’SAR: A new approach for protein engineering and screening

We present a strategy that combines wet-lab experimentation and computational protein design for engineering polypeptide chains. The protein sequences were numerically coded and then processed using Fourier Transform (FT). Fourier coefficients were used to calculate the energy spectra called protein spectrum . We use the protein spectrum to model the biological activity/fitness of protein from sequence data. We assume that the protein fitness (catalytic efficacy, thermostabilty, binding affinity, aggregation, stability…) is not purely local, but globally distributed over the linear sequence of the protein. Our patented method does not require protein 3D structure information and find patterns that correlate with changes in protein activity (or fitness) upon amino acids residue substitutions. A minimal wet lab data set sampled from mutation libraries (single or multiple points mutations) were used as learning data sets in heuristic approaches that were applied to build predictive models. We show the performance of the approach on designed libraries for different examples1 and discuss how our approach can tackle epistatic phenomena2. We can screen up to 1 billion (109) protein variants in a very short time. F. Cadet, N. Fontaine, I. Vetrivel, M. Ng Fuk Chong, O. Savriama, X. Cadet, P. Charton (2018), Application of Fourier transform and proteochemometrics principles to protein engineering, BMC Bioinformatics (2018) 19:382, doi.org/10.1186/s12859-018-2407-8, https://rdcu.be/9qjp F. Cadet, N. Fontaine, G. Li, J. Sanchis, M. Ng Fuk Chong, R .Pandjaitan, I. Vetrivel 1, B. Offmann & M. T. Reetz (2018), A machine learning approach for reliable prediction of amino acid interactions and its application in the directed evolution of enantioselective enzymes, Scientific Reports 8(1), 16757, doi: 10.1038/s41598-018-35033-y. www.nature.com/articles/s41598-018-35033-