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Wu J.,Louisiana State University | Gaytan E.A.A.,Technological Institute of Nuevo Leon
European Journal of Information Systems | Year: 2013

Third-party interpersonal communications such as online seller reviews play an important role in buyers' purchase decisions in online markets. Although it is empirically clear that seller reviews (volume and valence) and product price contribute to buyers' willingness-to-pay (WTP) differently across various studies, it is theoretically less understood why such effects qualitatively differ (e.g., positive vs negative), rendering unclear managerial implications for online marketers. In this paper, we study the role of online seller reviews and product price in buyers' WTP. We offer a conceptual framework from a risk perspective in which we argue that the different effects of seller reviews and product price on buyers' WTP may emerge simultaneously in an online market. We highlight two important drivers for such qualitatively different effects: a difference in buyers' risk attitudes (averse, neutral, or seeking) and a difference in WTP measures (absolute or relative). We test our hypotheses and find good support for them both internally (an experimental study) and externally (an empirical study). Our research enhances the understanding of the relationship between online user reviews and online price dispersions while shedding light on better management of online user reviews for market makers. © 2013 Operational Research Society Ltd.

Romo Perea A.,Technological Institute of Nuevo Leon | Amezcua J.,University of Maryland University College | Probst O.,Technological Institute of Nuevo Leon
Journal of Renewable and Sustainable Energy | Year: 2011

The estimation of the long-term wind resource at a prospective site based on a relatively short on-site measurement campaign is an indispensable task in the development of a commercial wind farm. The typical industry approach is based on the measure-correlate-predict (MCP) method where a relational model between the site wind velocity data and the data obtained from a suitable reference site is built from concurrent records. In a subsequent step, a long-term prediction for the prospective site is obtained from a combination of the relational model and the historic reference data. In the present paper, a systematic study is presented where three new MCP models, together with two published reference models (a simple linear regression and the variance ratio method), have been evaluated based on concurrent synthetic wind speed time series for two sites, simulating the prospective and the reference site. The synthetic method has the advantage of generating time series with the desired statistical properties, including Weibull scale and shape factors, required to evaluate the five methods under all plausible conditions. In this work, first a systematic discussion of the statistical fundamentals behind MCP methods is provided and three new models, one based on a nonlinear regression and two (termed kernel methods) derived from the use of conditional probability density functions, are proposed. All models are evaluated by using five metrics under a wide range of values of the correlation coefficient, the Weibull scale, and the Weibull shape factor. Only one of all models, a kernel method based on bivariate Weibull probability functions, is capable of accurately predicting all performance metrics studied. © 2011 American Institute of Physics.

Galvan-Tejada C.E.,Technological Institute of Nuevo Leon | Carrasco-Jimenez J.C.,Technological Institute of Nuevo Leon | Brena R.,Technological Institute of Nuevo Leon
Procedia Computer Science | Year: 2013

User indoor positioning has been under constant improvement especially with the availability of new sensors integrated to the modern mobile devices. These sensory devices allow us to exploit not only infrastructures made for every day use, such as Wifi, but also natural infrastructure, as is the case of natural magnetic fields. In this work, we propose a novel approach that takes advantage of the benefits of using the magnetic sensor incorporated in most modern mobile devices, and the negligible variations of the Earth's magnetic field to position an individual with high accuracy. Most importantly, the methodology proposed allows us to avoid the burden of having to collect magnetic information in different directions in order to construct an accurate magnetic map, showing an improvement on methods that require the individuals to construct bigger magnetic maps that contain redundant information such as magnitude in different directions. © 2013 The Authors. Published by Elsevier B.V.

Villela L.,Technological Institute of Nuevo Leon | Bolanos-Meade J.,Johns Hopkins University
Drugs | Year: 2011

The current treatment of patients with acute myeloid leukaemia yields poor results, with expected cure rates in the order of 3040 depending on the biological characteristics of the leukaemic clone. Therefore, new agents and schemas are intensively studied in order to improve patients outcomes. This review summarizes some of these new paradigms, including new questions such as which anthracycline is most effective and at what dose. High doses of daunorubicin have shown better responses in young patients and are well tolerated in elderly patients. Monoclonal antibodies are promising agents in good risk patients. Drugs blocking signalling pathways could be used in combination with chemotherapy or in maintenance with promising results. Epigenetic therapies, particularly after stem cell transplantation, are also discussed. New drugs such as clofarabine and flavopiridol are reviewed and the results of their use discussed. It is clear that many new approaches are under study and hopefully will be able to improve on the outcomes of the commonly used '73' regimen of an anthracycline plus cytarabine with daunorubicin, which is clearly an ineffective therapy in the majority of patients. © 2011 Adis Data Information BV. All Rights Reserved.

Ramon-Fox F.G.,Technological Institute of Nuevo Leon | Sada P.V.,University of Monterrey
Revista Mexicana de Astronomia y Astrofisica | Year: 2013

Four transits of the exoplanet HAT-P-23b were recently observed with the 0.36 m telescope at the Universidad de Monterrey Observatory. The four light curves were successfully combined to obtain a resulting one with reduced scat- tering per bin. This curve was modeled using a Monte Carlo method to obtain the essential parameters that characterize the system. Assuming orbital param- eters such as eccentricity e and longitude of periastron ω from the discovery pa- per, we found values of Rp/R* = 0.1105+0.0015 -0.0013 for the planet-to-star radius ratio, a/R* = 4.23+0.06 -0.12 for the scaled semimajor axis, and an orbital inclination of the system of i = 87.9°+1.5 -2.2. We also derive an improved orbital period of 1.2128868 ± 0.0000004 days (To = 2, 454, 852.26542 ± 0.00018 BJD TDB) for the system. © Copyright 2013: Instituto de Astronomía, Universidad Nacional Autónoma de México.

Pacheco J.,University of Burgos | Angel-Bello F.,Technological Institute of Nuevo Leon | Alvarez A.,Autonomous University of Nuevo León
Journal of Scheduling | Year: 2013

In this paper we study a problem of sequencing jobs in a machine with programmed preventive maintenance and sequence-dependent set-up times. The problem combines two NP-hard problems, so we propose a heuristic method for solving it, which hybridizes multi-start strategies with Tabu Search. We compare our method with the only published metaheuristic algorithm for this problem on a set of 420 instances. The comparison favors the method developed in this work, showing that is able to find high quality solutions in very short computational times. © 2012 Springer Science+Business Media, LLC.

Mendez G.M.,Technological Institute of Nuevo Leon | De Los Angeles Hernandez M.,Technological Institute of Nuevo Leon
Information Sciences | Year: 2013

A proposed learning methodology based on a hybrid mechanism for training interval A2-C1 type-2 non-singleton type-2 Takagi-Sugeno-Kang fuzzy logic systems uses a recursive square-root filter to tune the type-1 consequent parameters and the steepest descent method to tune the interval type-2 antecedent parameters. The proposed hybrid-learning algorithm changes the interval type-2 model parameters adaptively to minimize some criterion function as new information becomes available and to match desired input-output data pairs. Its antecedent sets are type-2 fuzzy sets, its consequent sets are type-1 fuzzy sets, and its inputs are interval type-2 non-singleton fuzzy numbers with uncertain standard deviations. As reported in the literature, the performance indices of hybrid models have proved to be better than those of the individual training mechanisms used alone. Comparison with non-hybrid interval A2-C1 type-2 Takagi-Sugeno-Kang fuzzy logic systems and with non-hybrid A1-C0 type-1 Takagi-Sugeno-Kang fuzzy logic systems shows that the proposed hybrid mechanism is a well-performing non-linear adaptive method that enables the interval type-2 fuzzy model to match an unknown non-linear mapping and to converge very fast. Experiments were carried out involving the application of the hybrid interval A2-C1 type-2 non-singleton type-2 Takagi-Sugeno-Kang fuzzy logic systems for modeling and prediction of the scale-breaker entry temperature in a hot strip mill for three different types of coils. The results demonstrate how the interval type-2 fuzzy system learns from selected input-output data pairs and improves its performance as hybrid training progresses. © 2012 Elsevier Inc. All rights reserved.

Ayala-Gaytan E.A.,Technological Institute of Nuevo Leon | Diaz Duran-Hernandez A.,Technological Institute of Nuevo Leon
Salud Publica de Mexico | Year: 2015

Objective. Explain the variation in child malnutrition (CM), understood as low height for age (0 to 5 years old) for the period 1999-2006. Materials and methods. State estimations of child malnutrition and several indicators of subjacent probable causes of CM were employed, such as poverty indices, state product per capita, women scholar attainment and access to health and the sewage system. Panel data regression analysis with fixed and random effects were used to analyze the data. Results. The results indicate that the lack to access to health and sewage systems and poverty worsen CM, whereas women education helps to diminish CM. Conclusion. The study shows that infrastructure variables explain a significant part of the recent variation in DI across Mexican states, and that economic growth is not a sufficient condition to diminish DI.

Cuellar-Bermudez S.P.,Technological Institute of Nuevo Leon | Garcia-Perez J.S.,Technological Institute of Nuevo Leon | Rittmann B.E.,Arizona State University | Parra-Saldivar R.,Technological Institute of Nuevo Leon
Journal of Cleaner Production | Year: 2015

One of the most important industrial activities related to the greenhouse gases emissions is the cement manufacturing process, which produces large amounts of carbon dioxide (CO2). Only in 2010, 8% of CO2 global emissions were due to cement industry. In this work, the use of CO2 released by the cement sector is described as potential gas for microalgae culture since their biofixation efficiency is higher than terrestrial plants. Therefore, transformation of polluting gas fluxes into new and valuable products is feasible. In addition, bulk applications such as wastewater treatment and biofuels production can be coupled. Finally, microalgae biomass can be also used for the production of valuable compounds such as pigments, food supplements for both humans and animals, and fertilizers. In this review, flue gas emissions coupled to microalgae cultures are described. In addition, since microalgae can produce energy, the biorefinery concept is also reviewed. © 2014 The Authors.

Cardenas-Barron L.E.,Technological Institute of Nuevo Leon | Teng J.-T.,William Paterson University | Trevino-Garza G.,Technological Institute of Nuevo Leon | Wee H.-M.,Chung Yuan Christian University | Lou K.-R.,Tamkang University
International Journal of Production Economics | Year: 2012

Ben-Daya et al. (2010) established a joint economic lot-sizing problem (JELP) for a three-layer supply chain with one supplier, one manufacturer, and multiple retailers, and then proposed a heuristic algorithm to obtain the integral values of four discrete variables in the JELP. In this paper, we first complement some shortcomings in Ben-Daya et al. (2010), and then propose a simpler improved alternative algorithm to obtain the four integral decision variables. The proposed algorithm provides not only less CPU time but also less total cost to operate than the algorithm by Ben-Daya et al. (2010). Furthermore, our proposed algorithm can solve certain problems, which cannot be solved by theirs. Finally, the solution obtained by the proposed algorithm is indeed a global optimal solution in each of all instances tested. © 2011 Elsevier B.V. All rights reserved.

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