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Guayaquil, Ecuador

Olaya P.,ESPOL Polytechnic University
Computers and Geosciences | Year: 2015

Automated-image identification and quantification of minerals, pores and textures together with petrographic analysis can be applied to improve pore system characterization in sedimentary rocks. Our case study is focused on the application of these techniques to study the evolution of rock pore network subjected to super critical CO2-injection. We have proposed a Digital Image Analysis (DIA) protocol that guarantees measurement reproducibility and reliability. This can be summarized in the following stages: (i) detailed description of mineralogy and texture (before and after CO2-injection) by optical and scanning electron microscopy (SEM) techniques using thin sections; (ii) adjustment and calibration of DIA tools; (iii) data acquisition protocol based on image capture with different polarization conditions (synchronized movement of polarizers); (iv) study and quantification by DIA that allow (a) identification and isolation of pixels that belong to the same category: minerals vs. pores in each sample and (b) measurement of changes in pore network, after the samples have been exposed to new conditions (in our case: SC-CO2-injection). Finally, interpretation of the petrography and the measured data by an automated approach were done. In our applied study, the DIA results highlight the changes observed by SEM and microscopic techniques, which consisted in a porosity increase when CO2 treatment occurs. Other additional changes were minor: variations in the roughness and roundness of pore edges, and pore aspect ratio, shown in the bigger pore population. Additionally, statistic tests of pore parameters measured were applied to verify that the differences observed between samples before and after CO2-injection were significant. © 2015 Elsevier Ltd. Source

Chavez J.P.,ESPOL Polytechnic University
International Journal of Bifurcation and Chaos | Year: 2010

We consider parameter-dependent, continuous-time dynamical systems under discretizations. It is shown that fold-Hopf singularities are O(h p)-shifted and turned into fold-NeimarkSacker points by one-step methods of order p. Then we analyze the effect of discretizations methods on the local bifurcation diagram near BogdanovTakens and fold-Hopf singularities. In particular, we prove that the discretized codimension one curves intersect at the singularities in a generic manner. The results are illustrated by a numerical example. © 2010 World Scientific Publishing Company. Source

Davalos J.,ESPOL Polytechnic University
International Journal of Energy Economics and Policy | Year: 2016

This study analyses the validity of environmental Kuznets curve (EKC) hypothesis for the Asia-pacific Economic Cooperation Forum (APEC), within the period 1992-2012. Three econometric models are performed, which use different environmental quality indicators as dependent variable. Model 1: Uses carbon dioxide (CO2) total emissions in APEC, Model 2: Uses CO2 emissions generated from coal consumption, and Model 3: Uses CO2 emissions generate from petroleum consumption. Pedroni and Kao co-integration approach are applied for testing long-run relationship between variables for each model. Fully modified ordinary least squares method is employed for determining the elasticities of the long-run relationships. The analysis finds that an EKC is held under Model 1, and 3, but for Model 2 the relation between the variables does not show an inverted U shape behavior. Additionally descriptive analysis and Model 2 suggest that coal consumption has been increasing in last years, because of the effect in CO2 emissions; even more in this specific indicator, economic activity is leading to an unsustainable growth scenario in APEC. © 2016, Econjournals. All rights reserved. Source

Cardenas W.B.,ESPOL Polytechnic University
Viruses | Year: 2010

The members of the filoviruses are recognized as some of the most lethal viruses affecting human and non-human primates. The only two genera of the Filoviridae family, Marburg virus (MARV) and Ebola virus (EBOV), comprise the main etiologic agents of severe hemorrhagic fever outbreaks in central Africa, with case fatality rates ranging from 25 to 90%. Fatal outcomes have been associated with a late and dysregulated immune response to infection, very likely due to the virus targeting key host immune cells, such as macrophages and dendritic cells (DCs) that are necessary to mediate effective innate and adaptive immune responses. Despite major progress in the development of vaccine candidates for filovirus infections, a licensed vaccine or therapy for human use is still not available. During the last ten years, important progress has been made in understanding the molecular mechanisms of filovirus pathogenesis. Several lines of evidence implicate the impairment of the host interferon (IFN) antiviral innate immune response by MARV or EBOV as an important determinant of virulence. In vitro and in vivo experimental infections with recombinant Zaire Ebola virus (ZEBOV), the best characterized filovirus, demonstrated that the viral protein VP35 plays a key role in inhibiting the production of IFN-α/β. Further, the action of VP35 is synergized by the inhibition of cellular responses to IFN-α/β by the minor matrix viral protein VP24. The dual action of these viral proteins may contribute to an efficient initial virus replication and dissemination in the host. Noticeably, the analogous function of these viral proteins in MARV has not been reported. Because the IFN response is a major component of the innate immune response to virus infection, this chapter reviews recent findings on the molecular mechanisms of IFN-mediated antiviral evasion by filovirus infection. © 2010 by the authors. Source

Tapia-Rosero A.,ESPOL Polytechnic University | Tapia-Rosero A.,Ghent University | Bronselaer A.,Ghent University | De Tre G.,Ghent University
Information Sciences | Year: 2014

In this paper, we propose a method to identify groups of similarly shaped membership functions representing criterion preferences provided by a large group of experts in the context of group decision-making. Our hypothesis hereby is that similarly shaped membership functions reflect similar expert opinions. The proposed method uses a symbolic notation to depict each membership function taking into account its shape characteristics (i.e., slopes and preference levels) and the relative length approximations on its X-axis segments (i.e., core segments, left and right spreads). The symbolic notation significantly reduces the complexity to handle a large group of expert opinions expressed by membership functions, and facilitates their comparison for grouping purposes through a shape-similarity measure. The main goal of the method is to detect all membership functions that are relevant to represent trends or suitable concepts among a large group of people considered as experts. An illustrative example, demonstrating the applicability of the method, is included in the paper. © 2013 Elsevier Inc. All rights reserved. Source

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