University of Cuenca
  • Cuenca, Azuay, Ecuador
Recent publications
Photovoltaic and hydrokinetic systems are increasing their penetration in electrical distribution systems. This leads to problems of power fluctuations due to the intermittence of renewable sources that could compromise the stability and quality of the power grid. To address this issue, this paper presents a feasibility study of three power smoothing methods for a photovoltaic-hydrokinetic system using laboratory equipment to optimally replicate the real behavior of this type of hybrid system. The proposed algorithms are based on a hybrid storage system with supercapacitors and lithium-ion batteries, several analyzes are presented based on technical and economic parameters.
Several heritage cities face the need to modernize public lighting systems that are installed on the facades of buildings. The legal obstacles to intervene in heritage infrastructures create a different scenario than other cities. This circumstance raises the question if it is possible to install a modern, innovative lighting system, isolated from the electrical distribution system. This research analyzes the feasibility of modernizing the system using 304 mini photovoltaic generation plants, implementing a novel lighting system control process that indirectly uses sky brightness measurements based on current research at the Catholic University of Cuenca. As a case study, the Historic Center of the City of Cuenca-Ecuador, a World Heritage Site, whose system is made up of 1,252 luminaires, is analyzed. The results conclude that it is feasible to modernize the lighting service with the adoption of the proposed technologies and for control, a novel system based on indirect measurement of sky clarity has been developed. Finally, the political implications are analyzed in the framework of energy efficiency and modernization of the systems, as well as the recommendation to the political decision-makers. The study can be replicated in other cities of the world with similar characteristics.
  • Braulio LahuatteBraulio Lahuatte
  • Giovanny M. MosqueraGiovanny M. Mosquera
  • Sebastián Páez‐BimosSebastián Páez‐Bimos
  • [...]
  • Patricio CrespoPatricio Crespo
Traditional hydrometric data combined with environmental tracers such as water stable isotopes contributes to improve the understanding of catchment hydrology. Nevertheless, the application of isotopic tracers in headwater catchments of the tropical Andes with deep soils and permeable parent material influenced by recent volcanism remains limited. In this study, the stable isotopic composition of precipitation, soil water, wetlands, and streamflow was studied to provide insights into the hydrology of a small tropical Andean catchment with deep and permeable volcanic soils, ash layers, and fractured bedrock resulting from Holocene volcanic activity. Although local precipitation forms under isotopic equilibrium conditions, the stable isotopic composition of precipitation is influenced by atmospheric moisture recycling processes. The spatial and temporal variability of isotopic signals and the analysis of inverse transit time proxies (ITTPs) of surface (streamflow) and subsurface (soil and wetlands) waters indicate that vertical flow paths through the deep volcanic ash soils are dominant across the catchment. The strongly damped isotopic composition of these waters points to high soil and wetlands water storage, increasing the transit time or age of stream water in the hydrological system. These findings indicate that water mobilizing through subsurface flow paths – i.e., volcanic soils, ash layers, and cracks in the fractured bedrock resulting from Holocene volcanism – is the main contributor to streamflow generation. Comparison with previously published work from Andean catchments and other volcanic areas shows the diversity of hydrological conditions that can be found as a result of pedological and lithological differences shaped by volcanic activity. Therefore, site‐specific strategies may be needed to improve water resources management. This article is protected by copyright. All rights reserved.
Vascular epiphytes layer is an important component of the forests; to understand their contribution to the ecosystem, it is imperative to assess the factors which affect their distribution, composition, and diversity. We studied the ecology of vascular epiphytes in Andean Mountain Forests of different successional stages, in a scenario that allowed us to determine some relationships between the composition of the epiphyte community and the tree communities, along with environmental and historic land use gradients. The research design included the sampling of 22 plots with a total of 3248 trees, including tree ferns with DBH ≥10 cm. Each tree was measured and identified to species level and was divided into three vertical strata, recording the diversity and frequency of vascular epiphytes present in each stratum. In these forests, we evaluated the variation of the composition, richness, and density of vascular epiphytes using the ADONIS analysis, evaluating the influence of two factors: the successional stage of the forest community and the tree vertical strata. We then explored which predictor variables, such as climate, spatial correlation, and host tree characteristics, explained the variation in epiphytes, using linear and variance partitioning models. In addition, we determined the preference of epiphytes for host tree species, using indicator tree species of successional stages. For each host tree species, we identified associated vascular epiphytes and their indicator species level was analyzed to determine epiphyte-host species with traits of specialist species. We found that epiphyte species richness and density were significantly higher in older forest communities. Epiphyte density was higher in the upper canopy of the hosts. The climate affected the composition of the epiphytes, while precipitation, elevation, crown height, and basal area significantly explained epiphyte richness and density. Preferential and indifferent epiphytes on indicator host species of intermediate and late succession suggest the existence of complex associations. The age of the forest succession, climatic factors, and certain characteristics of the host species have a major impact on the ecology of vascular epiphytes.
Statement of problem The biologically oriented preparation technique is a concept with a vertical tooth preparation, gingitage, an immediate interim restoration preserving the clot, and a specific laboratory technique aiming to adapt the marginal periodontal tissue to a remodeled emergence profile of the crown. However, the published scientific evidence on this subject is limited. Purpose The purpose of this systematic review was to analyze whether using the biologically oriented preparation technique leads to improved clinical outcomes in terms of probing depth, gingival inflammation index, gingival marginal stability, and fewer mechanical and biological complications. Material and methods Recommendations from the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used in this systematic review. An electronic search of the MEDLINE/PubMed, EMBASE, Science Direct, Wiley Online Library, Cochrane, and ProQuest databases was made for articles published between March 2010 and July 2021 using keywords. Three reviewers selected and analyzed all articles that mentioned the biologically oriented preparation technique and met the inclusion criteria. Results A total of 6 articles met the inclusion criteria: 1 prospective randomized clinical study, 1 randomized clinical study, 1 prospective clinical study, and 3 case series. According to these studies, of all the teeth treated with the biologically oriented preparation technique, probing depth (greater than 3 mm) increased in only 2.3%, gingival inflammation was present in 22.8%, gingival recession occurred in 1.7% (decreased gingival stability), and mechanical and biological failures occurred in 4.4% of the teeth. Conclusions Fixed dental prosthesis treatments performed following the concept of the biologically oriented preparation technique did not increase probing depth and showed a moderate rate of gingival inflammation, lower recession rates, and lower mechanical and biological failures at the 5-year follow-up. The biologically oriented preparation technique appears to be a viable alternative technique for obtaining satisfactory and stable clinical results up to 5 years. Long-term randomized clinical trials are recommended to reach more conclusions about this protocol.
A key step in creating efficient and long-lasting catalysts is understanding their deactivation mechanism(s). On this basis, the behavior of a series of Pd/corundum materials during several hydrogen adsorption/desorption cycles was studied using temperature-programmed desorption coupled with mass spectrometry and aberration-corrected transmission electron microscopy. The materials, prepared by impregnation and by sputtering, presented uniform well-dispersed Pd nanoparticles. In addition, single atoms and small clusters of Pd were only detected in the materials prepared by impregnation. Upon exposure to hydrogen, the Pd nanoparticles smaller than 2 nm and the single atoms did not present any change, while the larger ones presented a core–shell morphology, where the core was Pd and the shell was PdHx. The results suggest that the long-term activity of the materials prepared by impregnation can be attributed solely to the presence of small clusters and single atoms of Pd.
The socio-ecological metabolism of the water connects concepts that emerge out of the complexity of ecosystems, linking endosomatic processes that are indispensable for society while forming different hierarchic levels and relations among as well as aligning to their par-ticularities. The consumptive uses of Cuenca city in their different categories and social metabolism both at rural and urban levels were assessed, inquiring about diverse typologies of the city's water. Water Metabolic Rates (WMR) were calculated for each one of the con-sumptives' uses gauged in liters per hour of human activity. Our results indicate that farming and industrial uses of water were highly inefficient. Linked to farms, both consumption of water and metabolic rates were higher in the rural areas. While paid work showed higher metabolic rates than households. Rural households evidenced a greater use of water and higher metabolic rates than urban households as water use combines human consumption and family farming. This research determined the water metabolism of the socio-ecological system in the canton of Cuenca, Ecuador through different dimensions of water metabolism. Formulating a system of flows and uses of water that were metabolized by different hierarchy levels of diverse consumptive uses within the aforementioned canton, as a tool to implement policies that guarantee water access and ecological metabolism, linking social dynamics within ecosystems.
Downscaling aims to take large-scale information and map it to smaller scales to reproduce local climate signals. An essential step in implementing a parsimonious downscaling model is the selection of a subset of relevant predictors that increase the simulation accuracy. According to relevant literature, predictive models that use predictors chosen through causality methods, not widely used in downscaling, are more interpretable and robust. Characteristics that do not necessarily pursue the selection methods are commonly used in machine learning (ML), where the primary objective is to maximize accuracy. This study then explores whether the improvement in interpretability and robustness of models that use causally selected predictors is not achieved at the expense of poor downscaling performance in terms of simulation accuracy. To this end, one set of three methods based on causality and one set of four standard predictor selection methods used in ML are compared, centered on the downscaling performance of rainfall in an Ecuadorian Andes basin. One causality-based selection method is based on Granger causality (GC), and two are based on a constraint-based algorithm for structure learning, namely the Peter and Clark algorithm (PCalg) and the based on PCalg and the momentary conditional independence (PCMCI). Regarding the methods used in ML, one is based on the variance of the predictors (variance threshold), two are based on univariate statistical tests (F test and mutual information), and one is based on the recursive elimination of predictors (RFE) according to their contribution to the prediction model. The number of methods in each set results from those that are considered standard in many ML libraries or have been used for regression or climatology (causality-based). The selected predictors are used to train statistical downscaling models based on the random forest and support vector machine learning algorithms to assess their performance and rank the selection methods. Among the most remarkable findings, the methods based on causality show a robust selection. For instance, the causality-based methods selected 53 different predictors in one of the considered stations, while the ML-based methods selected 73 for downscaling models with similar performance. Furthermore, when the predictors used in the best performing downscaling models are analyzed, it is shown that the different selection methods based on causality tend to choose a subset of predictors that do not differ greatly, contrary to the methods based on machine learning. This evidences a more concise selection of the causality-based methods. Finally, the evaluation metrics of the downscaling models showed that the best selection method is RFE, but the following best were consistently those based on causality (mainly PCMCI). The study evidences no significant performance detriment when using the causally selected predictors.
This study aimed to assess the effect of adding clinoptilolite in the diet on uterine health and reproductive performance in multiparous lactating dairy cows managed in a tropical pasture-based system above 2500 m of altitude. Seventy-seven multiparous Holstein crossbred cows from two farms were allocated randomly into two groups: clinoptilolite supplemented cows (CLG, n = 42) and non-supplemented cows as control (CG, n = 35). Cows from CLG were supplemented with clinoptilolite from 30 days (50 g/cow/day) before to 60 days after calving (200 g/cow/day). In CLG cows, percentages of uterine PMN leukocytes (P < 0.0001) and proportion of subclinical endometritis (P = 0.0187) were lower than in CG. The interval calving to first corpus luteum was shorter (P = 0.0759) in CLG than CG, and calving to first service interval was similar between treatments. Cows from CLG became pregnant 35 days earlier than CG cows (P = 0.0224). On farm A, calving to conception interval was 18.1 days longer in CLG than in CG (P = 0.3750); in farm B, this interval was 86.2 days shorter in CLG than in CG (P = 0.0002). In conclusion, daily addition of clinoptilolite in the diet decreased the percentage of uterine PMN leukocytes, the proportion of cows with subclinical endometritis, and shortened the calving-conception interval in multiparous lactating dairy cows.
Background: Invisible violence against women (IVAW) can be understood as the set of attitudes, behaviors, and subtle beliefs that men use to subordinate women and that are culturally accepted. These behaviors can be a risk factor for intimate partner violence (IPV), so it is important to design tools that allow us to detect it early. The aim of this study was to design and psychometrically assess a questionnaire for the detection of invisible violence against women (Q-IVAW). Methodology: A descriptive cross-sectional methodological study carried out in three phases: (1) development of the initial version; (2) pilot study (N = 51); and (3) final validation study (N = 990). The tool's reliability, validity, and legibility were assessed. To assess reliability, the internal consistency (Cronbach's α) was analyzed. The validity assessment included an analysis of content, criterion, and construct validity. Results: The EFA revealed that the Q-IVAW was comprised of five factors that explained 55.85% of the total variance found. The Q-IVAW showed very high reliability (α = 0.937), excellent content validity, and good construct validity. The criterion validity analysis showed a moderate correlation between A-IPVAW and Q-IVAW (r = 0.30; p < 0.001). Conclusion: The psychometric assessment of the Q-IVAW yielded good results, which could support the tool's ability to assess how often women are subjected to inviable violent behaviors by their partners.
La yema de huevo (YH) es un componente común de los diluyentes de semen por su eficacia para proteger la membrana de los espermatozoides del choque de frío durante la criopreservación y además de ser rica en proteínas, vitaminas, antioxidantes y fosfolípidos. No obstante, la YH es un componente no definido y al mismo tiempo peligroso por el riego de transmisión de agentes patógenos, por esta razón, es necesario evaluar el uso de otros componentes que disminuyan este problema; una alternativa poco estudiada es alcohol poli vinílico (APV). Por lo que en esta investigación se evaluó el efecto del APV y la YH suplementados al diluyente TCG (tris, ácido cítrico, glucosa) sobre la criosupervivencia de espermatozoides epididimarios (EE) de perro. Para ello, se recuperaron EE mediante la técnica de flujo retrógrado en 15 perros adultos orquiectomizados para conformar cinco agrupaciones (4-6 muestras epididimarias / agrupación). Cada muestra agrupada se dividió en dos alícuotas, que posteriormente fueron diluidas y congeladas usando dos aditivos suplementados al diluyente TCG: APV al 1 % (peso/volumen –p/v– [TCG–APV] y yema de huevo al 20 % (volumen/volumen –v/v– [TCG–YH]. Posterior a la descongelación, se analizaron las anormalidades morfológicas, la vitalidad (eosina / nigrosina), la integridad de membrana plasmática (ioduro de propido), y las variables cinemáticas (sistema CASA, SCA-2018®). Los resultados demostraron que la vitalidad e integridad de la membrana plasmática fueron superiores (P<0,05) en muestras congeladas con TCG–YH, en comparación con aquellas muestras congeladas con TCG–APV. Asimismo, las muestras congeladas con TCG–YH obtuvieron valores post-descongelación más altos (P<0,05) de variable cinemáticas como la motilidad total y progresiva, velocidades promedio y rectilínea, índice de rectitud y frecuencia de batida de flagelo, en comparación con las muestras congeladas con TCG–APV. En conclusión, la adición YH al medio TCG fue efectiva en la congelación de EE de perro, ya que mejoró la vitalidad, integridad de membrana plasmática y la cinética espermática; sin embargo, la adición de 1 % de APV no mejoró la respuesta a la criopreservación.
Scientific studies concerning the causes and consequences of the biodeterioration of stone monuments located at high altitudes in permanently cold, mountainous regions are scarce. For that reason, this study aimed to detect and identify the bacteria involved in the deterioration of this type of monument. To achieve this goal, we focused on the most important archeological Inca site in the Ecuadorian Andes: Ingapirca’s Temple of the Sun, built approximately 500 years ago at 3.100 m.a.s.l. We first examined the stone surfaces of the temple by scanning electron microscopy and showed the detrimental impact on the mineral structure of the green andesite mineral used to build the temple, caused by crustose lichen thalli and heterotrophic bacteria. Then, we isolated, characterized, and identified several of these bacteria. Most of them multiplied at a wide range of temperatures, from 4 °C to 30 °C, and were thus considered eurypsychrophiles. Actinobacteria and Proteobacteria species dominated the culturable fraction of this community. Several isolates produced metabolites that solubilized mineral phosphates at low temperatures; others solubilized iron-containing mineral fractions in the green andesite rock when tested in vitro. To the best of our knowledge, this is the first report related to the biodeterioration of an Inca monument at such an altitude in the Andes range.
The subducting process of Nazca plate beneath the South American tectonic plate governs the seismicity at the Andes region, making it one of the world’s most active seismic regions. The subduction and collision of the aseismic Carnegie Ridge (CR), and the segmentation and drift of the continental North-Andean Block (NAB) with an intricate system of geological faults, are the main seismogenic sources in Ecuador. The oblique convergence of the CR is causing a ploughing effect and shallow-focus earthquakes on the Ecuador shoreline and deep seismic activity in the Pastaza-Napo region at the Amazon basin. The North Andean Block ejection by the Carnegie Ridge collision develops a complex system of active faults along the Andes and shallow-focus earthquakes along Chingual-Cosanga-Pallatanga-Puná fault system. Geodynamic and seismic activity suggests that subduction of the prolongation of CR beneath Ecuador requires about 400 km from the Colombia-Ecuador-Peru trench and is the most influential factor in the development of Ecuador’s seismicity. Keywords: Ecuador; Carnegie ridge; North andean block; Nazca plate; Seismic hazard; Subduction; Seismicity
Background: Cervical cancer continues to be a major health problem in developing countries. Educational programs, as well as Pap and HPV screening and vaccination, are important tools to reduce the morbidity and mortality rates associated with this disease. The objective of this study is to explore the diverse knowledge and perceptions about cervical cancer and the different diagnostic tests for HPV of populations living in the rural parish "El Valle". Method: A qualitative study was conducted through eight focus groups, which included 46 participants from mixed ethnic groups. A phenomenological analysis was performed. Results: Four topics and seven sub-topics were identified. By analyzing all the narratives, it was possible to identify that the perception of cervical cancer was focused on its severity, secondary to its infectious process and screening periodicity. However, despite the diverse knowledge, indigenous people do not relate it to the human papilloma virus; in addition, there is also certain resistance to undergo the Pap smear test, for reasons such as inaccessibility and its sampling process. Conclusions: It is necessary to develop educational programs for the prevention of cervical cancer and to implement diagnostic alternatives to reach populations with precarious accessibility, as well as women who refuse to undergo the Pap smear test.
Buildings are one of the largest consumers of electrical energy, making it important to develop different strategies to help to reduce electricity consumption. Building energy consumption forecasting strategies are widely used to support demand management decisions, but these strategies require large data sets to achieve an accurate electric consumption forecast, so they are not commonly used for buildings with a short history of record keeping. Based on this, the objective of this study is to determine, through continuous hourly electricity consumption forecasting strategies, the amount of data needed to achieve an accurate forecast. The proposed forecasting strategies were evaluated with Random Forest, eXtreme Gradient Boost, Convolutional Neural Network, and Temporal Convolu-tional Network algorithms using 4 years of electricity consumption data from two buildings located on the campus of the University of Valladolid. For performance evaluation, two scenarios were proposed for each of the proposed forecasting strategies. The results showed that for forecasting horizons of 1 week, it was possible to obtain a mean absolute percentage error (MAPE) below 7% for Building 1 and a MAPE below 10% for Building 2 with 6 months of data, while for a forecast horizon of 1 month, it was possible to obtain a MAPE below 10% for Building 1 and below 11% for Building 2 with 10 months of data. However, if the distribution of the data captured in the buildings does not undergo sudden changes, the decision tree algorithms obtain better results. However, if there are sudden changes, deep learning algorithms are a better choice.
The growth of subtransmission network aims at satisfying load growth, maintaining a contingency level, and providing a high quality and reliable electricity service. Utilities direct the investments to reinforce this system and thus a meshed network with multiple-point feeding to the transmission system arises. At this point, an efficient alternative to achieve these objectives is to carry out a diagnosis of the network architecture and, taking advantage of the switching capability, to plan the switching of the subtransmission lines. An optimal subtransmission switching approach is proposed based on constrained multi-objective optimization that deals with energy losses and reliability, in addition to using information on the characteristics of loads and generation. A simulation-based optimization framework is constructed using the non-dominated genetic classification algorithm NSGA-II in the optimization phase and reliability assessment during simulation phase. As a result, a set of non-dominated solutions approximating the Pareto front is obtained, which allows the planner to make decisions based on its priorities and needs. The performance of the proposal is assessed with a real subtransmission system of an Ecuadorian power utility. This approach to the operational planning of a meshed subtransmission network constitutes a powerful decision-making tool that could be adopted by distribution utilities.
One of the most pressing issues in today’s society is environmental pollution. The principal source of historically high global carbon emissions (CO2) in the atmosphere is human-caused anthropogenic activities based on non-renewable energy sources. As a result, renewable energy systems have emerged as an alternative source of energy that is seen to be less harsh than fossil energy supplies, drawing substantial economic, environmental, and technological attention during the last decade. Our study aims to analyze the non-linear impacts of renewable energy used by human and their trading with each other on consumption-based CO2 for the Pakistan’s economy. The study covers the period from 1990 to 2019 and employed the non-linear autoregressive distributive lag model (NARDL) for assessing the non-linear impacts of renewable energy on consumption-based CO2. As NARDL provides the best results when there is a non-linear relationship between the variables of analysis, as well as their stationary at the different levels and on first difference. Our results show that there exists asymmetry in consumption-based CO2 association with renewable energy consumption and trade. The positive shocks in renewable forms (oil and gas) of energy consumption and negative shock in trade increase consumption-based CO2 emissions. This implies that policymakers can promote non-renewable energy distributed and environmentally-friendly trade for conserving the environment for future generations.
Background: Objective: To compare two in-vitro protocols to study the effect of simulated gastric acid on the mechanical properties of resins based composites(RBCs). Material and methods: Three RBC FILTEK Supreme XTE (FS), BRILLIANT EverGlow (BE), GrandioSo (GS) were used. They were randomly divided into a control group (CG) and two groups exposed to simulated gastric acid: a 6-month daily protocol (DG) and an accelerated 90-min protocol (AG). Vickers microhardness (VH) and flexural strength were evaluated at baseline and six months. Statistical analysis was performed using repeated measures ANOVA tests for VH and three-way for flexural strength data (α=0.05). Results: Daily exposure in the CG and DG groups caused a reduction in VH values and flexural strength (p<0.05). The majority of values in the AG remained stable, after an exposure of 90 min; FS (p=0.118) and GS (p=0.729) in VH and FS (p=0.377), BE (p=0.692) and GS (p=0.672) in flexural strength. Conclusions: Daily exposure during 6 months caused significant changes in the VH values and flexural strength of the RBCs. The acid-accelerated protocol did not cause the same magnitude of change in VH values and flexural strength seen at six months of daily exposure. Key words:Gastric acid, hardness, composite resins, flexural strength, dental materials.
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5,451 members
Victor Saquicela
  • Departamento de Ciencias de la Computación
Jan Feyen
  • Departamento de Recursos Hídricos y Ciencias Ambientales
Santiago Torres Contreras
  • Eléctrica Electrónica y Telecomunicaciones
Daniel Orellana
  • Facultad de Arquitectura
Lorena Siguenza-Guzman
  • Departamento de Ciencias de la Computacion
Av. 12 de Abril S/N y Agustín Cueva, Cuenca, Azuay, Ecuador
Head of institution
Maria Augusta Hermida
+593 74 051 000