73 research outputs found
Network-based Optimization Techniques for Wind Farm Location Decisions
This thesis develops network-based approaches to analysis and optimization of wind energy systems. The wind energy system is a complex system that produces a massive amount of wind speed data over time, characterized by high level of variability. We study this system using the powerful tools of graph theory and network analysis, which provide a valuable tool for extracting important information from systems generating large amounts of data.
The main contribution of this thesis is a network-based method for finding appropriate locations for wind farms that maximize the overall energy, while controlling the effects of wind speed variability. For this purpose, we constructed networks that model potential wind farm locations as vertices and represent the pairwise correlations of the corresponding wind speed measurements using edges. More specifically, two vertices are connected by an edge if the correlation of their wind speeds considered over the given time period is below zero. If the weights of vertices are given by the average wind speed at the corresponding locations, then the problem of finding appropriate locations for wind farms is formulated as the problem of finding a tightly knit cluster of vertices with high weights. More specifically, we model clusters using the graph-theoretic concept of a clique and its relaxations, 2-plex and 3-plex.
To test the proposed approaches, we used real data from Bolivian studies of wind velocities conducted over a 10-year period at 201 locations spanning the entire Bolivian territory. The solutions obtained using the proposed approaches provide sets of diverse locations with high possible wind energy outputs. In particular, using clique relaxations results in larger number of diversified locations compared to that given by the maximum clique solutions.
Another studied problem deals with determining a small number of locations that would be representative of the overall behavior of wind speeds in the whole system. This problem was addressed searching for small dominating sets in graphs where edges correspond to pairs of locations with positively correlated wind speeds.
Finally, we proposed a methodology for evaluating costs of setting up wind farms in certain locations in Bolivia. The cost of setting up wind farms involves many variables, wind speeds being an important factor in determining the profitability of the system. We observe that for sites with higher wind speeds the net present value (NPV) of setting up and operating wind farms is positive and the internal rate of return (IRR) is higher than the discount rate, which ensures some profit to the investor. More specifically, the study has shown that with wind speeds around 6.9 m/s, the 2MW and 3MW wind turbine installments yield IRR of 13% and 15%, respectively. On the other hand, we concluded that lower wind speeds would result in projects that would not be able to recover the investment in the first 25 years. However, these projects could be profitable if the government develops policies for some green credits, or carbon bonus as income for generating and selling clean energy produced from wind power plants. The results obtained in this study could help the governments and investors interested in developing wind energy farms in Bolivia and other countries with similar geographical characteristic
Innovativeness as a determinant of entrepreneurial orientation: analysis of the hotel sector
This paper analyses entrepreneurial orientation as a composite
formed of innovation, proactiveness and risk-taking. The empirical
data for this study were gathered from a survey sent to hotel
managers. The fieldwork was carried out between January and
June 2018. The process provided 102 valid questionnaires. Two
methods were used: structural equation modelling (PLS-SEM) and
fuzzy-set qualitative comparative analysis (fsQCA). This study
makes six key contributions and findings. First, the use of these
two methods provides robust and reliable results. Second, reliability
and validity values for innovativeness, proactiveness and risktaking
are satisfactory. Third, the operationalisation of entrepreneurial
orientation using the latent variables of innovativeness,
proactiveness and risk-taking is satisfactory in terms of reliability
and validity. Fourth, these three dimensions have a positive and
significant influence on entrepreneurial orientation. Fifth, innovativeness
is the most important dimension of entrepreneurial
orientation. Sixth, innovativeness is a necessary and sufficient condition
for entrepreneurial orientation
An innovative quick solidifying technique for the forensic investigation of brain circulation using addition silicones
Post-mortem study of the brain is extremely relevant to medico-legal autopsies. However, it can be difficult to handle due to its fragility. This article presents a study on the development of an arterial solidifying technique that can be applied to analyze arterial circulation, consequently easing the handling and later diagnosis of diseases in this anatomical site. Vinylpolysiloxane silicone is introduced into the internal carotid arteries until it completely fills the arterial tree, creating a detailed model of the arterial's internal anatomy. This technique is fast, easy to apply and requires no previous tissue fixation. In addition, it allows for further toxicological and pathological tests. In conclusion, this technique represents a simple, sensitive and efficient method to employ in conventional autopsies, which can help in the diagnosis of death
Pretransplant CMV-Specific T-Cell Immunity But Not Dose of Antithymocyte Globulin Is Associated With Recovery of Specific Immunity After Kidney Transplantation
Background: This is a prospective, multicenter, observational study in cytomegalovirus (CMV)-seropositive kidney transplant recipients with pretransplant CMV-specific cell-mediated immunity (CMV-CMI) receiving antithymocyte globulin (ATG). We aimed to investigate posttransplant CMV-CMI over time and the impact of the dose-dependent ATG.
Methods: CMV-CMI was assessed at days +30, +45, +60, and +90 after transplantation with the QuantiFERON-CMV assay. A reactive result (interferon-? [IFN-?] ? 0.2 IU/mL) indicated a positive CMV-CMI.
Results: A total of 78 positive CMV-CMI patients were enrolled in the study, of which 59.5% had a positive CMV-CMI at day +30 and 82.7% at day +90. Multivariate logistic regression analysis showed that ATG dose was not associated with positive CMV-CMI at any point. However, pretransplant IFN-? level (>12 IU/mL vs ?12 IU/mL) was associated with positive CMV-CMI at day +30 (odds ratio, 12.9; 95% confidence interval, 3.1-53.3; P < .001). In addition, all the patients who did not recover CMV-CMI at day +90 had a pretransplant IFN-? level ?12 IU/mL.
Conclusions: More than half of CMV-seropositive kidney transplant recipients receiving ATG recover (or maintain) CMV-CMI by the first month after transplantation. The pretransplant IFN-? level, but not the ATG dose, shows a strong association with the kinetics of this recovery.This work was supported by the Fundación Progreso y Salud, Consejería de Salud y Familias, Junta de Andalucía (grant number PI-0294-2014); Spanish Ministry of Science and Innovation, Instituto de Salud Carlos III (grant number CP 18/00073 to M. F. R.); Plan Nacional de I+D+i 2013–2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia e Innovación, Spanish Network for Research in Infectious Diseases (grant numbers REIPI RD16/0016/0002, RD16/0016/0003, RD16/0016/0007, RD16/0016/0008, RD16/0016/0009 and RD16/0016/0012); cofinanced by European Development Regional Fund “A way to achieve Europe,” Operative Program Intelligent Growth 2014- 2020; Spanish Network for Research in Renal Diseases (grant numbers RD16/0009/0006, RD16/0009/0008, RD16/0009/0013, RD16/0009/0014, RD16/0009/0019, RD16/0009/0034); Centro de Investigación Biomédica en Red Enfermedades Respiratorias (grant number CB06/06/0058); and Spanish Group for the Study of Infection in Transplantation and the Immunocompromised Host of the Spanish Society of Infectious Diseases and Clinical Microbiolog
Sensory perspectives of the consumption of chips-type snacks made from black bean (Phaseolus vulgaris L) and peanut (Arachis hypogaea Linn) flours by university students in the Toluca Valley
Objective: The objective of this study is to evaluate the sensory perspectives of chips-type snacks made from black bean dry (Phaseolus vulgaris L) and peanut (Arachis hypogaea Linn) flours in a university population.
Design/methodology/approach: Two formulations were realized from peanut and black bean previously toasted and milled: 1) (PF) 50% peanut flour, 12.5% rice flour and 12.5 % cornstarch; 2) (BbF) 50% black bean flour, 12.5% wheat flour and 12.5% cornstarch. Each mixture of flours was extruded and fried until obtained chips-type snacks. A statistical-descriptive study was carried out from the observation of the eating habits of university students in the State of Mexico. On other hand, an affective test was tested to evaluate the acceptance of chips-type snacks made with PF and BbF in the categories of odor, taste, hardness, and easy to break.
Findings/conclusion:
According to the questionnaire, the female gender has higher snack consumption than the male population. On another hand, potato chips are in third place as the most consumed snacks for women they preferred to consume them in their houses. Peanut and chickpea flour are the most preferred by the female population. There was no significant difference (p˃0.05) between the snacks prepared with PF and BbF, but 60% of the consumer accepted both snacks. It is concluded that the chips-type snacks made with different formulations could be a healthy alternative for the students, also it kind of products have good acceptability. Finally knowing the sensory perspectives could provide important information for developing healthier and easier-to-eat snacks.
Limitations on study/implications: More studies about the characterization of the chips-type snacks are required, also a mix of both legumes could be realized
Analysis of spontaneous resolution of cytomegalovirus replication after transplantation in CMV-seropositive patients with pretransplant CD8+IFNG+ response
This prospective study evaluates whether CMV-seropositive (R+) transplant patients with pretransplant CD8+IFNG+ T-cell response to cytomegalovirus (CMV) (CD8+IFNG+ response) can spontaneously clear the CMV viral load without requiring treatment. A total of 104 transplant patients (kidney/liver) with pretransplant CD8+IFNG+ response were evaluable. This response was determined using QuantiFERON-CMV assay. The incidence of CMV replication and disease was 45.2% (47/104) and 6.7% (7/104), respectively. Of the total patients, 77.9% (81/104) did not require antiviral treatment, either because they did not have CMV replication (n = 57) or because they had asymptomatic CMV replication that could be spontaneously cleared (n = 24). Both situations are likely related to the presence of CD8+IFNG+ response to CMV, which has a key role in controlling CMV infection. However, 22.1% of the patients (23/104) received antiviral treatment, although only 7 of them did so because they had symptomatic CMV replication. These patients developed symptoms in spite of having pretransplant CD8+IFNG+ response, thus suggesting that other immunological parameters might be involved, such as a dysfunctional CD4+ response or that they might have become QFNon-reactive due to the immunosuppression. In conclusion, around 80% of R+ patients with pretransplant CD8+IFNG+ response to CMV did not require antiviral treatment, although this percentage might be underestimated. Nevertheless, other strategies such as performing an additional CD8+IFNG+ response determination at posttransplant time might provide more reliable information regarding the patients who will be able to spontaneously clear the viremia
Detection of latent tuberculosis infection among migrant farmworkers along the US-Mexico border
Plan de acción estratégica 2015-2021 para la adaptación al cambio climático de comunidades campesinas ubicadas en centros de origen y diversificación de cultivos nativos sierra central y sur
El Plan de Acción Estratégica 2015-2021 tiene como objetivo general, integrar los intereses y visiones de las comunidades campesinas ubicadas en centros de origen y diversificación de cultivos nativos altoandinos y demás actores sociales clave, en el proceso de adaptación al cambio climático en la región altoandina. La estructura de este plan se planteó a partir de la revisión de la bibliografía, especialmente de experiencias previas como el Plan de Acción Estratégico para fortalecer la conservación y el uso de los recursos Fitogenéticos mesoamericanos para la adaptación de la agricultura al cambio climático -PAEM- (Bioversity International 2014), la Guía para la elaboración de estrategias regionales sobre Cambio Climático (MINAM 2011), el Plan de Acción de Adaptación y Mitigación (MINAM 2010), la experiencia de PACC Apurímac (PACCPERU y otros 2014), el Proyecto Manejo Sostenible de la Tierra MST Apurímac (MINAM 2011), entre otros y luego se definió a partir de los intereses y necesidades de las comunidades campesinas altoandinas sobre el cambio climático y la agrobiodiversidad
Estrategia de gamificación aplicada a métodos estadísticos en el proceso de aprendizaje en enseñanzas turísticas
Depto. de Economía Financiera y Actuarial y EstadísticaFac. de Ciencias Económicas y EmpresarialesFALSEsubmitte
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