Search results for "95"
showing 10 items of 2244 documents
Estimation of Granger causality through Artificial Neural Networks: applications to physiological systems and chaotic electronic oscillators
2021
One of the most challenging problems in the study of complex dynamical systems is to find the statistical interdependencies among the system components. Granger causality (GC) represents one of the most employed approaches, based on modeling the system dynamics with a linear vector autoregressive (VAR) model and on evaluating the information flow between two processes in terms of prediction error variances. In its most advanced setting, GC analysis is performed through a state-space (SS) representation of the VAR model that allows to compute both conditional and unconditional forms of GC by solving only one regression problem. While this problem is typically solved through Ordinary Least Sq…
Modelo Barcelona y política cultural: usos y abusos de la cultura por parte de un modelo emprendedor de desarrollo local
2015
El Modelo Barcelona de desarrollo local ha sido intensamente debatido· Desde su inicio en los años ochenta hasta la actualidad, diversos autores han analizado sus características como modelo, destacado sus éxitos y también sus puntos débiles. No obstante, menos atención ha recibido la relación que existe entre el modelo de desarrollo local y el modelo de política cultural, a pesar de que Barcelona también es internacionalmente conocida por su dinamismo cultural. De manera habitual, este modelo de política cultural ha sido interpretado como un instrumento en la agenda de desarrollo local. El presente artículo mostrará, a partir de análisis de diversos casos ejemplares, que la política cultur…
The onset of the rainy season and farmers’ sowing strategy for pearl millet cultivation in Southwest Niger
2011
A multi-year (2004-2009) field survey of on-farm sowing practices in 10 villages located in south-west Niger close to Niamey, is analysed to investigate the relationships (i) between rainfall and the sowing date of pearl millet and the risk of sowing failure, (ii) between sowing and meteorological/agro-climatic onset dates, (iii) between sowing/onset dates, and simulated and observed yield/biomass at the end of the season. Even if some villages sow without any synchronous or anterior rainfall, most parcels (73% out of the 1551 available cases) are sown during and just after a 2-day wet spell receiving at least 10 mm. In fact, there is a strong correlation (r = 0.82-0.95 depending on onset d…
Bayesian dynamic modeling of time series of dengue disease case counts
2017
The aim of this study is to model the association between weekly time series of dengue case counts and meteorological variables, in a high-incidence city of Colombia, applying Bayesian hierarchical dynamic generalized linear models over the period January 2008 to August 2015. Additionally, we evaluate the model’s short-term performance for predicting dengue cases. The methodology shows dynamic Poisson log link models including constant or time-varying coefficients for the meteorological variables. Calendar effects were modeled using constant or first- or second-order random walk time-varying coefficients. The meteorological variables were modeled using constant coefficients and first-order …
Predicting dengue fever outbreaks in French Guiana using climate indicators
2016
Background Dengue fever epidemic dynamics are driven by complex interactions between hosts, vectors and viruses. Associations between climate and dengue have been studied around the world, but the results have shown that the impact of the climate can vary widely from one study site to another. In French Guiana, climate-based models are not available to assist in developing an early warning system. This study aims to evaluate the potential of using oceanic and atmospheric conditions to help predict dengue fever outbreaks in French Guiana. Methodology/Principal Findings Lagged correlations and composite analyses were performed to identify the climatic conditions that characterized a typical e…
Robust H-Infinity Filter Design for Uncertain Linear Systems Over Network with Network-Induced Delays and Output Quantization
2009
This paper investigates a convex optimization approach to the problem of robust H-Infinity filtering for uncertain linear systems connected over a common digital communication network. We consider the case where quantizers are static and the parameter uncertainties are norm bounded. Firstly, we propose a new model to investigate the effect of both the output quantization levels and the network conditions. Secondly, by introducing a descriptor technique, using Lyapunov-Krasovskii functional and a suitable change of variables, new required sufficient conditions are established in terms of delay-dependent linear matrix inequalities (LMIs) for the existence of the desired network-based quantize…
The Sustainability of Cruise Tourism Onshore: The Impact of Crowding on Visitors’ Satisfaction
2019
The sustainability of cruise tourism has been questioned in relation to its negative effects on ports of call, among which crowding has recently become more pronounced. However, an understanding of how crowdedness influences cruise tourists&rsquo
Lipofuscin Hypothesis of Alzheimer’s Disease
2011
The primary culprit responsible for Alzheimer’s disease (AD) remains unknown. Aβ protein has been identified as the main component of amyloid of senile plaques, the hallmark lesion of AD, but it is not definitively established whether the formation of extracellular Aβ deposits is the absolute harbinger of the series of pathological events that hit the brain in the course of sporadic AD. The aim of this paper is to draw attention to a relatively overlooked age-related product, lipofuscin, and advance the hypothesis that its release into the extracellular space following the death of neurons may substantially contribute to the formation of senile plaques. The presence of intraneuronal Aβ, sim…
High temperature solid-catalized transesterification for biodiesel production
2010
Biodiesel has become more attractive recently because of its environmental benefits and the fact that it is made from renewable resources. Biodiesel is a mixture of monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats, mainly made of fatty acid glycerides. It is produced by transesterification processes in which oil or fat are reacted with a monohydric alcohol in the presence of a catalyst. The transesterification process is affected by reaction conditions, alcohol to oil molar ratio, type of alcohol, type and amount of catalysts, temperature and purity of reactants. Heterogeneous acid catalysts are quite efficient in promoting the…
Power Grid Integration and Use-Case Study of Acid-Base Flow Battery Technology
2021
There are many different types of energy storage systems (ESS) available and the functionality that they can provide is extensive. However, each of these solutions come with their own set of drawbacks. The acid-base flow battery (ABFB) technology aims to provide a route to a cheap, clean and safe ESS by means of providing a new kind of energy storage technology based on reversible dissociation of water via bipolar electrodialysis. First, the main characteristics of the ABFB technology are described briefly to highlight its main advantages and drawbacks and define the most-competitive use-case scenarios in which the technology could be applied, as well as analyze the particular characteristi…