Journal of Next-Generation Research 5.0
Not a member yet
7559 research outputs found
Sort by
Ontologies to interpret remote sensing images : why do we need them?
No full textInternational audienceThe development of new sensors and easier access to remote sensing data are significantly transforming both the theory and practice of remote sensing. Although data-driven approaches based on innovative algorithms and enhanced computing capacities are gaining importance to process big Earth Observation data, the development of knowledge-driven approaches is still considered by the remote sensing community to be one of the most important directions of their research. In this context, the future of remote sensing science should be supported by knowledge representation techniques such as ontologies. However, ontology-based remote sensing applications still have difficulty capturing the attention of remote sensing experts. This is mainly because of the gap between remote sensing experts' expectations of ontologies and their real possible contribution to remote sensing. This paper provides insights to help reduce this gap. To this end, the conceptual limitations of the knowledge-driven approaches currently used in remote sensing science are clarified first. Then, the different modes of definition of geographic concepts, their duality, vagueness and ambiguity, and the sensory and semantic gaps are discussed in order to explain why ontologies can help address these limitations. In particular, this paper focuses on the capacity of ontologies to represent both symbolic and numeric knowledge, to reason based on cognitive semantics and to share knowledge on the interpretation of remote sensing images. Finally, a few recommendations are provided for remote sensing experts to comprehend the advantages of ontologies in interpreting satellite images
Examining relationships between cloud‐resolving model parameters and total flash rates to generate lightning density maps
No full textInternational audienceForecasting the electrical activity of a storm is a difficult task because of the complexity of cloud electrification processes and the unforeseeable characteristics of lightning flashes. Nowadays, very few models are able to simulate explicitly the entire life cycle of the electric charges in clouds, which is a result of the balance between the charge separation rates (microphysics) and the charge neutralization rates by lightning flashes (physics of streamer discharges).The main objective of this study is to investigate which particular dynamical and/or microphysical parameter can serve as the best proxy for the total lightning activity. With this aim, eight storms were simulated with Meso-NH and its cloud electrical scheme. This model-to-model approach guarantees a full consistency between the dynamics, the microphysics and the lightning activity. Two approaches are followed to analyse the results. The first one considers the entire domain of simulation, while the second one concentrates on individual convective cells.Linear regressions between predicted flash rates and recorded parameters or proxies (total graupel mass, updraught volume with vertical velocity higher than 10 m/s, product of precipitating and non-precipitating ice mass flux and maximum updraught speed) are analysed to show the benefit of the cell-scale approach. Then, in order to evaluate the relationships, the HyMeX storm case of 24 September 2012 was simulated. The mass of graupel best represents the overall location of the lightning activity (RMSE of the flash rate density better than 10−2 fl min−1km−2) and locates the peak lightning flash rate well. The three other proxies tend to cause false alarms due to the y-intercept value of the regression equation
How resilient is La Réunion in terms of international tourism attractiveness: an assessment from unit root tests with structural breaks from 1981-2015
No full textInternational audienceEven if local policymakers increasingly claim that tourism is one of the key factors of future economic development for the French small island La Réunion, international tourist arrivals are observed to be locked in a stagnation phase since the beginning of the 2000s. Starting from this stylised fact, this article aims to study if this phenomenon results from major external events hurting this economy regularly. Next, by using univariate unit root procedures with structural breaks, we test for evidence of permanent or transitory effects of external shocks on international tourist inflows (total, by source markets, and by category) over the period 1981-2015. Finally, the empirical analysis allow us to reject the null of a unit root. Then, stagnation of tourism arrivals to La Réunion is not due to exogenous shocks but probably results from endogenous impediments within the domestic tourism industry and unsuitable public policies
Contaminación y regulación ambiental el franquismo
No full textInternational audienceLa historia de la percepción y de la determinación social, científica y política de los productos tóxicos, nocivos o peligrosos que voy intentar reconstruir, de cara a poder ayudar en el proyecto sobre los tóxicos del CEHIC de la UAB (Barcelona) y del Instituto de Historia de la Ciencia y de la Medicina López Piñero (Valencia), comienza en el siglo XIX y se termina en la era post-nuclear de los años ochenta. Esta historia esta ligada al desarrollo de la industria de forma capitalista, es decir, aumentando la producción y reduciendo sus costes para incrementar las ganancias de capital. Esto no quiere decir que la industria sólo produjese productos nocivos o tóxicos en esta era capitalista. Lo que sucede es que social, política y económicamente esta nocividad va a ser contestada y gestionada, con muy poco acierto en general, de manera más recurrente, tal y como demuestran las fuentes. A continuación veremos qué se denuncia como nocivo, tóxico o peligroso en los conflictos por contaminación desde finales del siglo XIX. Seguido de qué tipo de norma se crea para determinar dicha toxicidad. Bajo el franquismo se vuelven a desencadenar conflictos por contaminación y la dictadura intentó crear una reforma de la norma ambiental (el Reglamento de Actividades Molestas, Insalubres, Nocivas y Peligrosas en 1961). Sin embargo, este reglamento, como la norma anterior, a veces tenía la doble intención de proteger a la producción industrial, todo dependía de la interpretación. La percepción del daño fue progresivamente aumentando en las décadas siguientes llegando a la contaminación de industrias energéticas: refinerías y centrales nucleares. La nocividad y la norma (siglo XIX-primer franquismo) Por industrias contaminantes contamos en un primer momento con todo el entramado minero-metalúrgico
Flux prediction using artificial neural network (ANN) for the upper part of glycolysis
No full textInternational audienceThe selection of optimal enzyme concentration in multienzyme cascade reactions for the highest product yield in practice is very expensive and time-consuming process. The modelling of biological pathways is a difficult process because of the complexity of the system. The mathematical modelling of the system using an analytical approach depends on the many parameters of enzymes which rely on tedious and expensive experiments. The artificial neural network (ANN) method has been successively applied in different fields of science to perform complex functions. In this study, ANN models were trained to predict the flux for the upper part of glycolysis as inferred by NADH consumption, using four enzyme concentrations i.e., phosphoglucoisomerase, phosphofructokinase, fructose-bisphosphate-aldolase, triose-phosphate-isomerase. Out of three ANN algorithms, the neuralnet package with two activation functions, "logistic" and "tanh" were implemented. The prediction of the flux was very efficient: RMSE and R2 were 0.847, 0.93 and 0.804, 0.94 respectively for logistic and tanh functions using a cross validation procedure. This study showed that a systemic approach such as ANN could be used for accurate prediction of the flux through the metabolic pathway. This could help to save a lot of time and costs, particularly from an industrial perspective. The R-code is available at: https://github.com/DSIMB/ANN-Glycolysis-Flux-Prediction
A reduced stochastic model of core surface dynamics based on geodynamo simulations
No full textInternational audienceWe make use of recent geodynamo simulations to propose a reduced stochastic model of the dynamics at the surface of Earth's core. On decadal and longer periods, this model replicates the most energetic eigen directions of the geodynamo computation. Towards shorter timescales , it proposes a compensation for weaknesses of these simulations. This model furthermore accounts for the signature, in the geomagnetic secular variation, of errors of representativeness associated with unresolved processes. We incorporate the reduced stochastic model into a geomagnetic data assimilation algorithm-an augmented state ensemble Kalman filter-and apply it to re-analyze magnetic field changes over the period 1880-2015. Errors of representativeness appear to be responsible for an important fraction of the observed changes in the secular variation, as it is the case in the dynamo simulation. Recovered core surface motions are primarily symmetric with respect to the equator. We observe the persistence of the eccentric westward gyre over the whole studied era, and vortices that partly follow isocontours of the radial magnetic field at the core surface. Our flow models provide a good fit to decadal changes in the length-of-day, and predict its interannual variations over 1940-2005. The largest core flow acceleration patterns are found in an equatorial belt below 10 • in latitude, and are associated with non-axisymmetric features. No systematic longitudinal drift of acceleration patterns is found, even over the past decades where satellite data are available. The acceleration of the high latitude westward jet in the Pacific hemisphere is, during the satellite era, a factor 5 smaller than previously reported, and its structure shows some evidence for equatorial asymmetry. The era 1 of continuous satellite records provides enhanced contrast on the rapid core flow variations. The proposed assimilation algorithm offers the prospect of evaluating Earth-likeness of geodynamo simulations
Addition of Flucytosine to Fluconazole for the Treatment of Cryptococcal Meningitis in Africa: A Multicountry Cost-effectiveness Analysis
No full textInternational audienceBACKGROUND:Mortality from cryptococcal meningitis remains very high in Africa. In the ACTA trial, 2 weeks of fluconazole (FLU) plus flucytosine (5FC) was as effective and less costly than 2-week amphotericin-based regimens. However, many African settings treat with FLU monotherapy and the cost effectiveness of adding 5FC to FLU is uncertain.METHODS:Effectiveness and costs of FLU+5FC were taken from ACTA, which included costing analysis at the Zambian site. Effectiveness of FLU was derived from cohorts of consecutively enrolled patients, managed in respects other than drug therapy, as were participants in ACTA. FLU costs were derived from costs of FLU+5FC in ACTA, by subtraction of 5FC drug and monitoring costs.Cost-effectiveness of FLU+5FC vs FLU alone was measured as the incremental cost-effectiveness ratio (ICER). Probabilistic sensitivity analysis assessed uncertainties, and a bivariate deterministic sensitivity analysis examined the impact of varying mortality and 5FC drug costs on the ICER.RESULTS:Mean costs per patient were US628 (95%CI:557-709) for FLU. 10 week mortality was 35.1% (95%CI 28.9-41.7) with FLU+5FC and 53.8% (95%CI: 43.1-64.1) with FLU. At the current 5FC price of 65 (95%CI: 28-208) per life year saved. Reducing 5FC cost to between US0.40 per 500mg resulted in an ICER between US28 per life year saved.CONCLUSIONS:Addition of 5FC to FLU is cost-effective for cryptococcal meningitis treatment in Africa and if made available widely could substantially reduce mortality rates among HIV-infected persons in Africa
State and parameter estimation for a class of schistosomiasis models
No full textInternational audienceWe develop a general framework to estimate the proportion of infected snails and snail-human transmission parameter of a class of models that describes the evolution of schistosomiasis. To do so, we consider simultaneously the dynamics of schistosomiasis, captured by the homogeneous version of the classical MacDonald's model, and the measurable output: the number of female schistosomes per single host. The proposed method consists of designing an auxiliary dynamical system, called observer, whose solutions converge exponentially to those of the system capturing the schistosomiasis model. Moreover, we derive an estimation of the snail-human transmission rate, an unknown but key parameter in the dynamics of schistosomiasis. These estimations are central in two of the strategies of controlling schistosomiasis, namely the use of molluscicides and mass drug administration. To further investigate control strategies on a larger scale, we consider a heterogeneous model which consists of an arbitrary number of human groups or patches and an arbitrary number of freshwater sources, natural habitats of snails. Provided that the data of infected humans' worm burden in each patch or group is available, we provide a method of estimating the proportion of infected snails in each snail natural habitat, thereby providing a map on where to implement control strategy to mitigate or eliminate Schistosomiasis