Universidad Católica del Norte (Chile)
  • Antofagasta, Antofagasta, Chile
Recent publications
Parkinson’s disease (PD) is the second most common neurodegenerative disorder, and no efficient therapy able to cure or slow down PD is available. In this study, dehydrated red cabbage was evaluated as a novel source of bio-compounds with neuroprotective capacity. Convective drying was carried out at different temperatures. Total phenolics (TPC), flavonoids (TFC), anthocyanins (TAC), and glucosinolates (TGC) were determined using spectrophotometry, amino acid profile by LC-DAD and fatty acid profile by GC-FID. Phenolic characterization was determined by liquid chromatography-high-resolution mass spectrometry. Cytotoxicity and neuroprotection assays were evaluated in SH-SY5Y human cells, observing the effect on preformed fibrils of α-synuclein. Drying kinetic confirmed a shorter processing time with temperature increase. A high concentration of bio-compounds was observed, especially at 90 °C, with TPC = 1544.04 ± 11.4 mg GAE/100 g, TFC = 690.87 ± 4.0 mg QE/100 g and TGC = 5244.9 ± 260.2 µmol SngE/100 g. TAC degraded with temperature. Glutamic acid and arginine were predominant. Fatty acid profiles were relatively stable and were found to be mostly C18:3n3. The neochlorogenic acid was predominant. The extracts had no cytotoxicity and showed a neuroprotective effect at 24 h testing, which can extend in some cases to 48 h. The present findings underpin the use of red cabbage as a functional food ingredient.
El objetivo de la presente investigación fue evaluar si la motivación tiene un efecto moderador en la relación entre cursar una carrera no deseada y el bienestar psicológico en personas estudiantes de educación superior. La muestra estuvo conformada por 333 estudiantes; se evaluó si las personas se encontraban estudiando la carrera que habían deseado, su nivel de motivación con la carrera y su nivel de bienestar psicológico. Existe relación entre estar en la carrera deseada y mayores niveles de autoaceptación, dominio del entorno y propósito en la vida; la motivación tiene una relación estadísticamente significativa con todas las dimensiones del bienestar psicológico e influye en el aumento del crecimiento personal cuando la persona cursa una carrera que no era la deseada p<,0430. Se concluyó que existió un efecto moderador de la motivación en la relación entre la carrera deseada y la dimensión del bienestar psicológico “crecimiento personal”. Se propone que la motivación debería ser un foco de intervención en la población de personas estudiantes universitarias, como un factor influyente en el bienestar psicológico.
In this work, the authors identified opportunities for improvements in conversational systems. In order to solve the conversational systems learning problems, this investigation proposes a new architectural model for the conversational system “BRasa,” consisting of two subsystems. The first, “BRasa_Assistant,” is oriented to direct communication with users, and the second “BRasa_LDS” is oriented to conversational system learning inspired by Linguistic Data Summarization techniques. BRasa_LDS generates summaries in natural language, which incorporate new knowledge into the conversational system database. In addition, is proposed a system of indicators for the self-assessment of the human–computer interaction of the conversational system. In the analysis results section, three sets of tests were designed to measure the quality of conversational system responses. The proposal is validated based on the criteria applicability and adequacy of the conversational system responses. It is shown that the application of linguistic data summarization techniques for learning conversational systems improves the behavior of these systems significantly.
Agent-based simulation is a powerful technique used for simulating real-life situations. This method involves simulating individual agents and their interactions with each other and the environment. Several platforms, such as GAMA and MASON, are available for developing agent-based simulations. In this chapter, we present a case study that showcases the versatility of agent-based simulation across different domains. Through various scenarios, we demonstrate that this approach can be successfully employed in diverse areas, such as traffic modeling, understanding the behavior of drifting objects, and teaching the operation of a sugar mill boiler. These simulations can be built from the scratch or using development platforms, providing a unique approach to modeling complex systems. By using agent-based simulations, researchers can test different scenarios and understand how agents interact within a system, leading to valuable insights for decision-making and problem-solving.
Dimension reductions (DR) help people make sense of image collections by organizing images in the 2D space based on similarities. However, they provide little support for explaining why images were placed together or apart in the 2D space. Additionally, they do not provide support for modifying and updating the 2D representation to explore new relationships and organizations of images. To address these problems, we present an interactive DR method for images that uses visual features extracted by a deep neural network to project the images into 2D space and provides visual explanations of image features that contributed to the 2D location. In addition, it allows people to directly manipulate the 2D projection space to define alternative relationships and explore subsequent projections of the images. With an iterative cycle of semantic interaction and explainable-AI feedback, people can explore complex visual relationships in image data. Our approach to human–AI interaction integrates visual knowledge from both human-mental models and pre-trained deep neural models to explore image data. We demonstrate our method through examples with collaborators in agricultural science and other applications. Additionally, we present a quantitative evaluation that assesses how well our method captures and incorporates feedback.
One of the most important goals of urban management is to provide comfort and well-being for all citizens. According to the population trend of the world, a massive segment of the future population will be the elderly. Therefore, it is crucial to pay attention to the needs of this segment of society. In this regard, the concept of an age-friendly city that provides a favorable urban environment for the elderly has entered the world’s scientific literature. Because one of the essential land utilization that the elderly have a lot of connection with is health-therapeutic use, the current research has been carried out to evaluate the current health-treatment situation of Songhor city in terms of its usefulness for the elderly. In the second step, the most important drivers influencing the location of these uses have been identified from the perspective of related experts. This research is applied in terms of purpose and descriptive-analytical in terms of research method. The required data has been collected using library-documentary studies, field surveys, and the distribution of questionnaires from related experts. According to the study’s findings, more than 60% of treatment facilities in Songhor city are inaccessible to the elderly. This difficulty varies by therapeutic use; in some cases, it is less difficult than the average, while in others, it is more difficult. In addition, three factors–investment cost (V3), rivalry (V10), and population density (V8)–have been identified as the age-friendly city’s main drivers out of a total of 18 main variables. The study’s findings indicate that the global population is aging, and urban managers and officials should design urban environments following the requirements of the projected population by putting forth medium- and long-term plans.
In this paper, we study the thermodynamical and mathematical consistencies for a non-singular early-time viscous cosmological model known as soft-Big Bang, which was previously found in [N. Cruz, E. González and J. Jovel, Phys. Rev. D 105, 024047 (2022)]. This model represents a flat homogeneous and isotropic universe filled with a dissipative radiation fluid and a cosmological constant [Formula: see text], which is small but not negligible, in the framework of Eckart’s theory. In particular, we discuss the capability of the solution in the fulfillment of the three following conditions: (i) the near equilibrium condition, which is assumed in Eckart’s theory of non-perfect fluids, (ii) the mathematical stability of the solution under small perturbations, and (iii) the positiveness of the entropy production. We have found that this viscous model can describe the radiation domination era of the [Formula: see text]CDM model and, at the same time, fulfill the three conditions mentioned by the fulfillment of a single constraint on the bulk viscous coefficient [Formula: see text], finding also that this non-singular model has a positive energy density in the infinity past which is infinity hotter with a constant entropy.
Background The harsh conditions of high-altitude environments are known to drive the evolution of physiological and morphological traits in endothermic animals. These conditions are expected to result in the adaptive evolution of protein coding genes encoded in mitochondrial genomes that are vital for the oxidative phosphorylation pathway. In this study, we formally tested for signatures of adaptive evolution on mitochondrial protein coding genes in Tapirus pinchaque and other odd-toed ungulates inhabiting high-elevation environments. Results The AT-rich mitochondrial genome of T. pinchaque is 16,750 bp long. A phylomitogenomic analysis supports the monophyly of the genus Tapirus and families in the Perissodactyla. The ratio of non-synonymous to synonymous substitutions demonstrated that all mitochondrial genes undergo purifying selection in T. pinchaque and other odd ungulates living at high elevations. Over this negative background selection, Branch Models suggested that cox3 and nad6 might be undergoing stronger purifying selection than other mitochondrial protein coding genes. Furthermore, Site Models suggested that one and four sites in nad2 and nad5, respectively, could be experiencing positive selection. However, these results were supported by Likelihood Ratio Tests but not Bayesian Empirical Bayes posterior probabilities. Additional analyses (in DataMonkey) indicated a relaxation of selection strength in nad6, evidence of episodic diversifying selection in cob, and revealed episodic positive/diversifying selection signatures for two sites in nad1, and one site each in nad2 and nad4. Conclusion The mitochondrial genome of T. pinchaque is an important genomic resource for conservation of this species and this study contributes to the understanding of adaptive evolution of mitochondrial protein coding genes in odd-toed ungulates inhabiting high-altitude environments.
New models of agglomeration cast the urban productivity premium as the outcome of agglomeration economies, a spatial sorting of skilled entrepreneurs and greater selection effects leading to less, but more productive businesses. We provide descriptive evidence of the spatial distribution of growing early-stage businesses in Chile that concurs with the theory. We show, first, that while business entry rates increase systematically with the size of a region, the rates of growing early-stage businesses are not related to the levels of agglomeration. Second, we show that, on the contrary, average early-stage business productivity, the levels of human capital and business exit rates all relate positively with agglomeration. Third, we estimate regression models that verify the expected relationships between agglomeration factors and regional growing early-stage-business activity. The results for Chile suggest that the disadvantages of agglomeration largely offset the benefits , and therefore there is no obvious location penalty to venturing in peripheral areas. Entrepreneurship policies in less-developed countries should not target excessively to specific industries and regions, as they might curtail an entrepreneurial potential that is ubiquitous.
The aim of this study was to analyze the psychological distress of young adults exposed to alienating behaviors during childhood/adolescence. Four hundred and sixteen adults responded to the online survey. A brief sociodemographic questionnaire, the Brief Symptom Scale, and a questionnaire on adverse childhood experiences were included. The analyses revealed that individuals who experienced one or more alienating behaviors exhibited higher levels of anxiety, depression, somatization, and overall psychological distress. Furthermore, even after controlling for the effect of other adverse childhood experiences, alienating behaviors had a significant impact on psychological distress in adulthood. This highlights an understudied aspect of alienating behaviors, i.e., their conjunction or parallelism with other adverse childhood experiences.
At-sea distributions of seabird species are strongly associated with the distribution patterns of their prey, which are influenced by physical oceanic features. During breeding and non-breeding seasons, seabirds move extraordinary distances among different environments. However, foraging site fidelity by seabirds appears to be high in areas of known high productivity, such as frontal zones and upwellings. Here, we present a tracking study for the Peruvian diving-petrel Pelecanoides garnotii, an endemic seabird of the highly productive Humboldt Current System, to assess whether adults use the same foraging areas throughout the year, combining data from nest monitoring and global location sensors (GLS) deployed on 12 individuals between two breeding seasons (2013–2014 and 2014–2015), in Choros Island (29°15′S; 71°32′W), Chile. Two main foraging areas were registered. During the breeding season, adults moved in the northern direction, between 60 to 144 km away from their colony, foraging in areas with high primary productivity. During the non-breeding period, they moved to southern latitudes (~ 1200 km). Adults spent 37% and 63% of their time in flight/land and on/underwater activities, respectively. We determined that birds move northward from their colony during breeding, where prey availability seems more predictable throughout the year. However, during the non-breeding period, it is likely that other environmental factors influence the distribution pattern of the Peruvian diving-petrel.
Small, circular holes, lined with a thin gypsum veneer, and closely associated with gypsum tumuli (domes), occur at Salar de Pajonales, a salt flat in the northern Andes, Chile. We propose a model in which the formation of the gypsum‐lined holes, and less commonly the formation of the tumuli itself, is controlled by the unique juxtaposition of physiographic, geologic and hydrologic conditions. On a regional scale, Salar de Pajonales is unusual compared to other salars, as it is located close to a large magmatic inflation centre (Lazufre), lies along strike of major regional structural trends, is a large ephemeral lake and contains high salt concentrations. On a basin scale, the lined holes are only present along strike of lineaments that are directly linked to the local stress regime. In turn, these lineaments control the location of degassing and subsequently the formation of the lined holes in the gypsum tumuli and, in part, the tumuli themselves.
Artisanal gold mining (AGM) is a very important topic, of which the environmental and social impact has been widely studied. However, there are few studies on operational efficiency, financial analysis, and the lack of mine planning. The purpose of this work was to investigate whether AGM operation without mercury is sustainable. The following parameters were analyzed in the case study: the general situation, interaction with the company that owns the area, production, drilling and blasting, loading and transport, freight to the centralized plant, workforce, materials and supplies, geological control planning and the relationship with the processing plant. Even without the mercury variable, AGM was found to be unsustainable. The lack of planning and operational inefficiency did not allow for continuous operation. The results of this research provide guidance on the future steps the current government and society should take to achieve sustainable AGM.
Low-temperature vacuum drying (LTVD) has shown great potential for drying vegetables. It could avoid excessive degradations of active compounds with potential therapeutic agents. In this study, the effect on several relevant bioactive compounds, anti-inflammatory activity, and anti-proliferative activity of broccoli (Brassica oleracea var. italica) were evaluated. Effects of other drying methods, including vacuum drying (VD), convective drying (CD), infrared drying (IRD), and freeze drying (FD), were also comparatively evaluated. The results of all dried samples showed high polyunsaturated fatty acid contents (of up to 71.3%) and essential amino acid contents (of up to 8.63%). The LTVD method stands out above the other drying methods, since it obtained the highest content of total phenols, chlorogenic acid, and ferulic acid. Both the LTVD and CD samples demonstrated high anti-inflammatory and anti-proliferative activities. These CD and LTVD samples were also the most active against the breast carcinoma MDA-MB-23 cell line. Due to the good retention of bioactive compounds via LTVD, the obtained dried broccoli here can be used in a near time as an ingredient for the development of novel natural products with anti-inflammatory and anti-proliferative effects.
The deterioration of reinforced concrete structures in marine environments presents multiple problems due to the premature degradation of reinforced steel. This work aimed to study the corrosion of reinforced A630-420H steel when exposed to a 0.5 M NaCl solution. Although this carbon steel is the most widely used material for reinforced concrete structures in Chile, there is limited research on its resistance to corrosion when in contact with saline solutions. The electrochemical reactions and their roles in the corrosion rate were studied using linear sweep voltammetry, weight loss, scanning electron microscopy, and X-ray diffraction techniques. This analysis is unique as it used the superposition model based on mixed potential theory to determine the electrochemical and corrosion parameters. The outcomes of this study show that A630-420H steel has a higher corrosion rate than those of the other commercial carbon steels studied. This fact can be attributed to the competition between the cathodic oxygen reduction reaction and hydrogen evolution reaction, which also depends on the environmental conditions, exposure time, stabilization of the corrosion products layer, and presence of chloride ions. Additionally, the results under mechanical stress conditions show a brittle fracture of the corrosion product oriented longitudinally in the direction of the bend section, where the presence of pores and cracks were also observed. The corrosion products after corrosion were mainly composed of magnetite and lepidocrocite oxide phases, which is in concordance with the electrochemical results.
In this paper, we perform a detailed group classification for a generalized convection-reaction-diffusion equation with three unknown functions. Specifically, we determine all the functional forms for the unknown functions where the given equation admits nontrivial Lie point symmetries. The classification problem provides us with eight families of equations summarized in four categories. The admitted Lie symmetries form the four Lie algebras [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. For the four families of the classification problem we calculate the one-dimensional optimal system and we derive all the similarity transformations which reduce the partial differential equation into an ordinary differential equation. Applications of the similarity transformations are presented while exact solutions are derived.
Managing the energy produced to support industries and various human activities is highly relevant nowadays. Companies in the electricity markets of each country analyze the generation, transmission, and distribution of energy to meet the energy needs of various sectors and industries. Electrical markets emerge to economically analyze everything related to energy generation, transmission, and distribution. The demand for electric energy is crucial in determining the amount of energy needed to meet the requirements of an individual or a group of consumers. But energy consumption often exhibits random behavior, making it challenging to develop accurate prediction models. The analysis and understanding of energy consumption are essential for energy generation. Developing models to forecast energy demand is necessary for improving generation and consumption management. Given the energy variable’s stochastic nature, this work’s main objective is to explore different configurations and parameters using specialized libraries in Python and Google Collaboratory. The aim is to develop a model for forecasting electric power demand using fuzzy logic. This study compares the proposed solution with previously developed machine learning systems to create a highly accurate forecast model for demand values. The data used in this work was collected by the European Network of Transmission System Operators of Electricity (ENTSO-E) from 2015 to 2019. As a significant outcome, this research presents a model surpassing previous solutions’ predictive performance. Using Mean Absolute Percentage Error (MAPE), the results demonstrate the significance of set weighting for achieving excellent performance in fuzzy models. This is because having more relevant fuzzy sets allows for inference rules and, subsequently, more accurate demand forecasts. The results also allow applying the solution model to other forecast scenarios with similar contexts.
Coastal societies have lived at the seaward edge of the Atacama Desert since at least 12,000 years ago. Kelp forest ecosystems provide evidence for important subsistence activity along the entire Chilean coast through fishing and gathering. Despite their importance, especially in hyperarid contexts with limited plant abundance, there is scarce evidence of kelp in archaeological contexts, hampering the study of kelp use in the past. In the present study, we use the presence of small marine invertebrates, inhabitants of stipes and holdfasts of macroalgae, as proxies that indicate past kelp presence. We analyze samples of three species of snails (Tegula atra, Tegula tridentata, and Diloma nigerrima) and one limpet (Scurria scurra) from nine archaeological sites dated between 7,000 and 500 cal years before present located around the area of Taltal (25°Lat S). Modern samples of these species were collected to reconstruct the size of fragmented archaeological shells and subsequently estimate the size of harvested kelps. Through this approach, we estimated the size and relative abundance of kelp used by coastal groups that inhabited the southern part of the Atacama Desert for around 6,500 years. Our results are a contribution to the scarce information on the presence and use of kelp in the prehistory of the Americas and contribute to comparative perspectives with other areas of the world where the use of kelp by humans in the past has already been explored.
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3,569 members
Miguel Angel Cabrera
  • Department of Chemistry and Pharmaceutical Sciences
Ranjit Das
J M Alonso Vega
  • Department of Marine Biology
Claudio D. Miranda
  • Departamento de Acuicultura
Jaime Aburto
  • Department of Marine Biology
Avenida Angamos 0610, 1270709, Antofagasta, Antofagasta, Chile
Head of institution
Jorge Tabilo
+56 55 2355000