Scalable Dynamic Mixture Model with Full Covariance for Probabilistic Traffic Forecasting

Deep learning-based multivariate and multistep-ahead traffic forecasting models are typically trained with the mean squared error (MSE) or mean absolute error (MAE) as the loss function in a sequence-to-sequence setting, simply assuming that the errors follow an independent and isotropic Gaussian or Laplacian distributions. However, such assumptions are often unrealistic for real-world traffic forecasting tasks, where the probabilistic distribution of spatiotemporal forecasting is very complex with strong concurrent correlations across both sensors and forecasting horizons in a time-varying manner. In this paper, we model the time-varying distribution for the matrix-variate error process as a dynamic mixture of zero-mean Gaussian distributions. To achieve efficiency, flexibility, and scalability, we parameterize each mixture component using a matrix normal distribution and allow the mixture weight to change and be predictable over time. The proposed method can be seamlessly integrated into existing deep-learning frameworks with only a few additional parameters to be learned. We evaluate the performance of the proposed method on a traffic speed forecasting task and find that our method not only improves model performance but also provides interpretable spatiotemporal correlation structures.Comment: 11 pages, 4 figures, 2 tabl

Sorption of nalidixic acid onto micrometric and nanometric magnetites: experimental study and modeling

International audienceThe sorption of nalidixic acid (NA) was studied onto three kinds of magnetite characterized by different particle sizes (from micrometric to nanometric) and surface properties. Experiments were performed under static batch and dynamic flow conditions. Obtained results indicate that kinetics and extent of sorption was strongly affected by the particle size of tested magnetites. Ionic strength effect was less significant suggesting that aggregation state of the magnetite particles did not affect the sorption. During kinetic sorption experiments, apparent rate constant normalized to solid mass was faster for nanosized magnetite while an opposite trend was observed for the surface area-normalized rate constants. Infrared data suggested the possibility of similar surface interactions on both microsized and nanosized magnetites. Transport of NA in magnetite-packed column was found associated to the instantaneous sorption without any significant effect of kinetic limitation. Breakthrough curves (BC) and sorption extent in columns were calculated by using Thomas, Yan and Yoon-Nelson models. Sorption capacities predicted by Thomas or Yan model were in good agreement with that determined by integrating total area above BC. However, Thomas model failed particularly to predict an accurate concentration at lower and higher time points of the BC. These findings have strong implications in relation to the transport and removal of environmental pollutants in natural and engineered systems

A Learning Approach for Adaptive Image Segmentation

International audienceAs mentioned in many papers, a lot of key parameters of image segmentation algorithms are manually tuned by designers. This induces a lack of flexibility of the segmentation step in many vision systems. By a dynamic control of these parameters, results of this crucial step could be drastically improved. We propose a scheme to automatically select segmentation algorithm and tune theirs key parameters thanks to a preliminary supervised learning stage. This paper details this learning approach which is composed by three steps: (1) optimal parameters extraction, (2) algorithm selection learning, and (3) generalization of parametrization learning. The major contribution is twofold: segmentation is adapted to the image to segment, and in the same time, this scheme can be used as a generic framework, independant of any application domain

Inverse Electron-Demand [4 + 2]-Cycloadditions of Ynamides: Access to Novel Pyridine Scaffolds

Functionalized polycyclic aminopyridines are central to the chemical sciences, but their syntheses are still hampered by a number of shortcomings. These nitrogenated heterocycles can be efficiently prepared by an intramolecular inverse electron demand hetero Diels–Alder ( ih DA) cycloaddition of ynamides to pyrimidines. This ihDA/rDA sequence is general in scope and affords expedient access to novel types of aminopyridinyl scaffolds that hold great promise in terms of exit vector patterns

Patient versus provider incentives in long-term care

How do patient and provider incentives affect the provision of long-term care? Our analysis of 551 thousand nursing home stays yields three main insights. First, Medicaid-covered residents prolong their stays instead of transitioning to community-based care due to limited cost-sharing. Second, when facility capacity binds, nursing homes shorten Medicaid stays to admit more profitable out-of-pocket private payers. Third, providers react more elastically to financial incentives than patients. Thus, targeting provider incentives through alternative payment models, such as episode-based reimbursement, is more effective than increasing patient cost-sharing in facilitating transitions to community-based care and generating long-term care saving

Weak short-term survival of radio-tagged Pin-tailed Sangrouse (Pterocles alchata) in France raises questions about capture and attached transmitters

Un des outils à la disposition des biologistes de la conservation pour étudier comment les espèces utilisent les habitats, thème central en écologie des populations, est la radio-télémétrie. Cette technique impose la capture et la pose d’émetteurs radio. Ces actions peuvent avoir un effet préjudiciable sur les oiseaux mais dans le cadre d’espèces difficiles à détecter, la méthode reste la seule pour acquérir des informations précises. Nous examinons ici le bilan d’un test de suivi radio-télémétrique sur le Ganga cata (Pterocles alchata) en France. Il en ressort que le taux de mortalité à court terme est très élevé. Aucune des informations collectées ne permet de l’expliquer clairement. Ces résultats sont comparés et discutés avec ceux obtenus en Espagne sur cette espèce.Radio-telemetry is widely used by conservation biologists for collecting data on habitat use by animal species, a central topic in population ecology. For this purpose, the capture of individuals and attachment of transmitters on animals are necessary. Those actions might have a harmful effect on birds but when species are difficult to detect it remains the only method available. We report results of a radio-telemetry study on Pin-tailed Sandgrouse (Pterocles alchata) in France. Although the capture and attachment of transmitters are possible, short-term mortality is very high. Collected data do not explain such a rate. We compare those results to a recent study on the same species in Spain and to a meta-analysis on birds

Integration and mining of malaria molecular, functional and pharmacological data: how far are we from a chemogenomic knowledge space?

The organization and mining of malaria genomic and post-genomic data is highly motivated by the necessity to predict and characterize new biological targets and new drugs. Biological targets are sought in a biological space designed from the genomic data from Plasmodium falciparum, but using also the millions of genomic data from other species. Drug candidates are sought in a chemical space containing the millions of small molecules stored in public and private chemolibraries. Data management should therefore be as reliable and versatile as possible. In this context, we examined five aspects of the organization and mining of malaria genomic and post-genomic data: 1) the comparison of protein sequences including compositionally atypical malaria sequences, 2) the high throughput reconstruction of molecular phylogenies, 3) the representation of biological processes particularly metabolic pathways, 4) the versatile methods to integrate genomic data, biological representations and functional profiling obtained from X-omic experiments after drug treatments and 5) the determination and prediction of protein structures and their molecular docking with drug candidate structures. Progresses toward a grid-enabled chemogenomic knowledge space are discussed.Comment: 43 pages, 4 figures, to appear in Malaria Journa

Infection par Helicobacter pylori: prévalence et facteurs associés dans une population tout venant d’après une recherche par test respiratoire à l’urée marquée au carbone 14

Introduction: l´infection à Helicobacter pylori (H. pylori) est fréquente dans les pays en voie de développement comme le Bénin. Ce germe peut favoriser la survenue d´affections gastroduodénales, allant de la gastrite au cancer gastrique. Les différentes études réalisées au Bénin sur cette bactérie ont utilisé des méthodes telles que la sérologie, l´étude anatomo-pathologique de biopsies ou la recherche d´antigène dans les selles. La présente étude avait pour but d´évaluer la prévalence d´infection par H. pylori et les facteurs associés à cette infection en utilisant un test respiratoire. Méthodes: il s´agissait d´une étude prospective descriptive sur 150 patients qui ont réalisé le test respiratoire à l´urée marquée au carbone 14. Seuls les patients admis pour test respiratoire et ayant donné leur consentement étaient inclus. Une fiche d´enquête a été remplie au fur et à mesure. Une analyse univariée par régression logistique simple a permis d´identifier les facteurs associés à l´infection par H. pylori à un seuil de 0,05. La stratégie d´analyse multivariée a consisté à inclure dans le model toutes les variables dont la valeur de p est inférieure à 0,20. La procédure manuelle descendante a été utilisée jusqu´à obtenir le modèle final qui a permis de retenir de facteurs associés avec des rapports de cotes ajustés. Résultats: l´âge moyen était de 44,4±15,8 ans; avec des extrêmes de 5 ans et 84 ans. Les hommes représentaient 54% de la population d´étude. Des 150 sujets, 82 (57,8%) avaient un niveau d´instruction supérieur contre 8 (5,6%) non scolarisés, 116 (80,6 %) vivaient en couple, 24 (36%) vivaient dans une chambre de plus de 10 personnes et 84 (59,6%) étaient des chrétiens. Les principaux motifs ayant conduit à la réalisation de test respiratoire étaient: douleurs abdominales mal systématisées (53,3%; 70/150), douleurs épigastriques provoquées (35,3%; 53/150), les épigastralgies (20,7%; 31/150), un syndrome ulcéreux (16%; 24/150). La prévalence d´H. pylori par test respiratoire au sein de la population étudiée était de 34,7% (52/150). En analyse multivariée, les variables significativement associées à l´infection à l´H. pylori étaient: l´âge moyen [AOR (95%IC) = 1,02; OR (95% IC) = 1,00-1,05 et p = 0,01] et la notion d´un traitement antérieur d´éradication de l´H. pylori [AOR (95%IC) = 4,79; OR (95% IC) = 1,50-13,86 et p = 0,006]. Aucune comorbidité étudiée n´était associée à l´infection par H. pylori dans notre série. Conclusion: la prévalence d´H. pylori trouvée par cette méthode est faible (34,7%). Elle est significativement associée à l´âge moyen et à la notion d´un traitement antérieur d´éradication de l´H. pylori

High-density functional-RNA arrays as a versatile platform for studying RNA-based interactions

We are just beginning to unravel the myriad of interactions in which non-coding RNAs participate. The intricate RNA interactome is the foundation of many biological processes, including bacterial virulence and human disease, and represents unexploited resources for the development of potential therapeutic interventions. However, identifying specific associations of a given RNA from the multitude of possible binding partners within the cell requires robust high-throughput systems for their rapid screening. Here, we present the first demonstration of functional-RNA arrays as a novel platform technology designed for the study of such interactions using immobilized, active RNAs. We have generated high-density RNA arrays by an innovative method involving surface-capture of in vitro transcribed RNAs. This approach has significant advantages over existing technologies, particularly in its versatility in regards to binding partner character. Indeed, proof-of-principle application of RNA arrays to both RNA-small molecule and RNA-RNA pairings is demonstrated, highlighting their potential as a platform technology for mapping RNA-based networks and for pharmaceutical screening. Furthermore, the simplicity of the method supports greater user-accessibility over currently available technologies. We anticipate that functional-RNA arrays will find broad utility in the expanding field of RNA characterization