Playa Ancha University
  • Valparaíso, Chile
Recent publications
Freshwater ecosystems are important contributors to the global greenhouse gas budget and a comprehensive assessment of their role in the context of global warming is essential. Despite many reports on freshwater ecosystems, relatively little attention has been given so far to those located in the southern hemisphere and our current knowledge is particularly poor regarding the methane cycle in non-perennially glaciated lakes of the maritime Antarctica. We conducted a high-resolution study of the methane and carbon dioxide cycle in a lake of the Fildes Peninsula, King George Island (Lat. 62°S), and a succinct characterization of 10 additional lakes and ponds of the region. The study, done during the ice-free and the ice-seasons, included methane and carbon dioxide exchanges with the atmosphere (both from water and surrounding soils) and the dissolved concentration of these two gases throughout the water column. This characterization was complemented with an ex-situ analysis of the microbial activities involved in the methane cycle, including methanotrophic and methanogenic activities as well as the methane-related marker gene abundance, in water, sediments and surrounding soils. The results showed that, over an annual cycle, the freshwater ecosystems of the region are dominantly autotrophic and that, despite low but omnipresent atmospheric methane emissions, they act as greenhouse gas sinks.
The frequency and intensity of extreme events in coastal wetlands is increasing due to climate change. These, in combination with other threats such as habitat loss, can have strong effects on the biodiversity and ecosystem services of coastal wetland ecosystems. Here we examined how traditional (community composition and taxonomic diversity) and alternative indices based on body size (size diversity and the slope of size spectra) respond to single and combined effects of anthropogenic disturbances, extreme event disturbances, and key environmental drivers, for both aquatic and terrestrial invertebrates in Mediterranean coastal wetlands in Chile. We studied 18 coastal wetlands over more than 500 km along the Chilean coast. We applied both univariate (GLMMs and GAMMs) and multivariate statistics (RDA and variation partitioning) to identify additive and non-additive effects on invertebrates. We also examined latitudinal trends, and tested the potential of alternative metrics to detect interactions between disturbances. We found latitude-specific vulnerability to disturbances in Chilean coastal wetlands. Non-additive effects were more important for aquatic invertebrates, while additive effects were more important for terrestrial invertebrates. In many cases, disturbance effects depended on the environmental conditions of study sites, especially salinity. This study suggests that size-based metrics may be better than taxonomic metrics at detecting interactions among different disturbances, especially for aquatic invertebrates.
Pinnipeds are sentinel species for marine pollution, but their role as vectors of trace elements (TEs) or rare earth elements (REEs) to ecosystems has been poorly studied. The present study tested pinniped feces for 61 elements, including REEs. Feces of adult seals (Mirounga leonina, Hydrurga leptonyx) from Fildes Bay, King George Island, Antarctica, were analyzed by ICP-MS. TEs varied by several orders of magnitude across the suite examined herein, with Fe, Al, Zn, Mn, HgII and Sr as the top six in both species. Of the REEs, Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sc, Sm, Tb, Y and Yb were found consistently in all samples and ranged from 0.935 to 0.006 μg g⁻¹ d.w. The results show that both species act as biovector organisms of TEs and REEs through feces in remote environments, whose actual impacts and long-term fate need further exploration.
Diseño de secuencias de enseñanza y aprendizaje en física: una mirada desde el uso del contexto Moraga-Toledo Resumen El objetivo de este estudio fue determinar el uso del contexto en el diseño de secuencias de enseñanza y aprendizaje (SEA) por parte del profesorado en formación inicial de física (PFFI). Se llevó a cabo un análisis del contenido de las SEA, a través de una segmentación estructural y por actividades. Se construyó un sistema de categorías a partir de la implementación de la rúbrica de indicadores de contexto (RIC). Los resultados muestran que el PFFI utiliza el contexto en el diseño de las SEA para crear oportunidades de aprendizajes en las distintas fases del ciclo. El PFFI utiliza contextos de tipo personal y persistentes durante el diseño de las SEA, presentando dificultades para incorporar el enfoque contextual. Se concluye que el diseño de SEA constituye un escenario formativo que permite la reflexión del PFFI acerca del proceso. Palabras Abstract The objective of this study was to determine the use of context in the design of teaching and learning sequences (TLS) by teachers in initial physics training (PFFI). TLS content analyses were conducted through a structural and activity-based segmentation. A system of categories was constructed based on the implementation of the rubric of context indicators (RIC). The results showed that the PFFI uses the context in the design of the SEAs to create learning opportunities in the different phases of the cycle. The PFFI uses personal and persistent contexts during the design of SEAs, presenting difficulties in incorporating the contextual approach. It is concluded that the design of SEAs constitutes a formative scenario, which allows PFFI to reflect on the process.
Using carbon and nitrogen stable isotope values, we analyzed the trophic position (TP) and the isotopic niche width of lanternfishes from three different fishing grounds in the Southern Pacific Ocean. Fishes from Perú had slightly higher δ13C values compared with fish from Chilean fisheries grounds. In contrast, δ15N values increased with latitude (North to South). Myctophids TP differed between the three fishing grounds (highest in Central Chile, lowest in Peru). Peruvian fishes had a smaller isotopic niche than the lanternfishes of the Chilean fishing grounds.
The virus-to-prokaryote ratio (VPR) has been used in many ecosystems to study the relationship between viruses and their hosts. While high VPR values indicate a high rate of prokaryotes' cell lysis, low values are interpreted as a decrease in or absence of viral activity. Salar de Huasco is a high-altitude wetland characterized by a rich microbial diversity associated with aquatic sites like springs, ponds, streams and a lagoon with variable physicochemical conditions. Samples from two ponds, Poza Rosada (PR) and Poza Verde (PV), were analyzed by epifluorescence microscopy to determine variability of viral and prokaryotic abundance and to calculate the VPR in a dry season. In addition, to put Salar de Huasco results into perspective, a compilation of research articles on viral and prokaryotic abundance, VPR, and metadata from various Southern hemisphere ecosystems was revised. The ecosystems were grouped into six categories: high-altitude wetlands, Pacific, Atlantic, Indian, and Southern Oceans and Antarctic lakes. Salar de Huasco ponds recorded similar VPR values (an average of 7.4 and 1.7 at PR and PV, respectively), ranging from 3.22 to 15.99 in PR. The VPR variability was associated with VA and chlorophyll a, when considering all data available for this ecosystem. In general, high-altitude wetlands recorded the highest VPR average (53.22 ± 95.09), followed by the Oceans, Southern (21.91 ± 25.72), Atlantic (19.57 ± 15.77) and Indian (13.43 ± 16.12), then Antarctic lakes (11.37 ± 15.82) and the Pacific Ocean (6.34 ± 3.79). Physicochemical variables, i.e., temperature, conductivity, nutrients (nitrate, ammonium, and phosphate) and chlorophyll a as a biological variable, were found to drive the VPR in the ecosystems analyzed. Thus, the viral activity in the Wetland followed similar trends of previous reports based on larger sets of metadata analyses. In total, this study highlights the importance of including viruses as a biological variable to study microbial temporal dynamics in wetlands considering their crucial role in the carbon budgets of these understudied ecosystems in the southern hemisphere.
Purpose This exploratory study aims to investigate variations in voice production in the presence of background noise (Lombard effect) in individuals with nonphonotraumatic vocal hyperfunction (NPVH) and individuals with typical voices using acoustic, aerodynamic, and vocal fold vibratory measures of phonatory function. Method Nineteen participants with NPVH and 19 participants with typical voices produced simple vocal tasks in three sequential background conditions: baseline (in quiet), Lombard (in noise), and recovery (5 min after removing the noise). The Lombard condition consisted of speech-shaped noise at 80 dB SPL through audiometric headphones. Acoustic measures from a microphone, glottal aerodynamic parameters estimated from the oral airflow measured with a circumferentially vented pneumotachograph mask, and vocal fold vibratory parameters from high-speed videoendoscopy were analyzed. Results During the Lombard condition, both groups exhibited a decrease in open quotient and increases in sound pressure level, peak-to-peak glottal airflow, maximum flow declination rate, and subglottal pressure. During the recovery condition, the acoustic and aerodynamic measures of individuals with typical voices returned to those of the baseline condition; however, recovery measures for individuals with NPVH did not return to baseline values. Conclusions As expected, individuals with NPVH and participants with typical voices exhibited a Lombard effect in the presence of elevated background noise levels. During the recovery condition, individuals with NPVH did not return to their baseline state, pointing to a persistence of the Lombard effect after noise removal. This behavior could be related to disruptions in laryngeal motor control and may play a role in the etiology of NPVH. Supplemental Material
The permanence of informal settlements in Latin America reflects insufficient public policies and markets incapable of providing housing for poor groups in society. However, it is also a manifestation of the pulse of residents to manage housing alternatives. This article describes the first impacts of the COVID-19 health emergency on housing, based on the example of the consolidation of the Campamento Altos de Placilla Nuevo. The research focused on the resident's elections, building processes, and inhabit experiences through a mixed and participatory methodology. It is concluded that, although the pandemic was an accelerating factor that exposed the vulnerability of low-income families, living in the camp made it possible to improve their living conditions, both in a context of abandonment and uncertainty.
The osmotic activity produced by internal, non‐permeable, anionic nucleic acids and metabolites causes a persistent and life‐threatening cell swelling, or cellular edema, produced by the Gibbs‐Donnan effect. This evolutionary‐critical osmotic challenge must have been resolved by LUCA or its ancestors, but we lack a cell‐physiology look into the biophysical constraints to the solutions. Like mycoplasma, early cells conceivably preserved their volume with Cl−, Na+, and K+‐channels, Na+/H+‐exchangers, and a light‐dependent bacteriorhodopsin‐like H+‐pump. Here, I simulated protocells having these ionic‐permeabilities and inhabiting an oceanic pond before the Great‐Oxygenation‐Event. Protocells showed better volume control and stable resting potentials at lower external pH and higher temperatures, favoring a certain type of extremophile life. Prevention of Na+‐influx at night, with low bacteriorhodopsin activity, required deep shutdown of highly voltage‐sensitive Na+‐channels and extremely selective K+‐channels, two conserved features essential for modern neuronal encoding. The Gibbs‐Donnan effect universality implies that extraterrestrial cells, if they exist, may reveal similar volume‐controlling mechanisms. A scenario for the origin of life: In a pre‐GOE oceanic pond, an early cell or protocell, filled with negative macromolecules and metabolites, controls its natural tendency to inflate, due to the Gibbs‐Donnan effect, with a bacteriorhodopsin‐like proton‐pump together with other ion‐transporting proteins, producing a negative resting‐potential and internal alkalinization .
Desde nuestro profundo pesar, y con nuestro mayor respeto, los autores del presente texto queremos referirnos a parte del legado de quien ha sido una figura inspiradora para muchas generaciones de estudiantes y entomólogos/as, como homenaje póstumo y en recuerdo permanente de nuestra formadora en el ámbito de la entomología, profesora Elizabeth Chiappa..........
The effect of multi-component training on the specific performance is under-researched in wrestlers. The aim of this study was to determine the effect of 6-weeks of multicomponent training on The Special Wrestling Fitness Test (SWFT) performance in wrestlers who were preparing for an international championship, and their inter-individual adaptive variability. The wrestlers (n=13; 7 female; all international-level) underwent technical-tactical and physical fitness training 6-weeks before the championship, 12 sessions per week (i.e., 36 h per week). Before and after the intervention the athletes were assessed with the SWFT, a wrestling-specific competitive performance test that includes measurements for throws, heart rate response to the SWFT, and the SWFT index. Significant pre-post intervention improvements were noted for throws (pre = 23.5 ± 2.9; post = 24.9 ± 3.6; P = 0.022) and SWFTindex (pre = 14.9 ± 2.2; post = 14.1 ± 2.2; P = 0.013). In conclusion, six weeks of multi-component training improves wrestling-specific competitive performance in highly-trained wrestlers, although with a meaningful inter-subject variability.
Abstract: All the variables that arise in family dynamics can have significant effects on the lives of children concerning their nutritional status and motor development. The objective of this study was to relate the PAL of parents to the level of motor development and the BMI of their children. A total of 198 subjects participated, with the age of the students ranging between 8 and 10 years. To measure the BMI, the norms for the nutritional evaluation of children and teenagers from 5 to 19 years were used; to identify the motor behaviors, the TGMD-2 Test was used; and to identify the level of physical activity of parents, the International Physical Activity Questionnaire (IPAQ) was used. For the analysis, the independent samples t-test and the non-parametric Mann–Whitney U test (Wilcoxon) were used, and for the correlational analysis, Spearman’s rho test was applied. This study found no significant correlation between the activity level of parents and nutritional status variables (p = 0.162), or between the PAL variables of parents and the motor development of their children (p = 0.738). A parent’s level of physical activity does not have a direct relationship with the nutritional status or the motor development of their children.
Introducción: Los escolares que practican actividad física regularmente poseen mayor autoestima y autoconcepto académico respecto a quienes no lo practican; se desconoce si esta condición se mantiene en contexto de pandemia por la COVID-19. Objetivo: Comparar la autoestima con el autoconcepto académico en escolares chilenos según sexo y hábito de actividad física. Secundariamente, asociar la autoestima con el autoconcepto académico de los escolares. Métodos: Estudio transversal que evaluó a 108 escolares (50,9 % mujeres) con una edad media de 13,96 + 2,85 años. Los instrumentos utilizados fueron la escala de Rosenberg, la escala de autoconcepto académico y una pregunta dicotómica relativa al hábito de actividad física. Se realizaron comparaciones con t de Student, U de Mann Whitney y asociaciones con ji cuadrado de Pearson. Resultados: Se encontraron diferencias significativas a favor de los hombres en autoestima (p= 0,007), sin diferencias en el resto de las variables, ni entre escolares físicamente activos vs. escolares físicamente inactivos. Además, se encontró asociación estadísticamente significativa entre la autoestima con la autoeficacia académica (p< 0,05), rendimiento percibido (p< 0,001) y puntaje total de la escala de autoconcepto académico (p< 0,001), en hombres, mujeres, escolares físicamente activos, escolares físicamente inactivos y en la muestra total. Conclusión: Existe asociación entre la autoestima con la autoeficacia académica, el rendimiento percibido y el puntaje total de la escala de autoconcepto académico en escolares chilenos, independiente del sexo y hábito de actividad física. Adicionalmente, existen diferencias de medias estadísticamente significativas en favor de los hombres para la autoestima.
The aim of this study was to compare jump-related performance after plyometric training on harder vs. softer surfaces in rugby sevens players. Fourteen players were randomly assigned into harder surface group (H-G, n = 7) and softer surface group (S-G, n = 7). Three times per week, in the morning, the players performed a plyometric training on different surfaces and strength training in the afternoon. Before and after 4-week intervention period, were assessed with squat jump (SJ), countermovement jump (CMJ), and CMJ with arms (CMJA) tests to measure vertical jump displacement (d), rate of force development (r), and power (p). The main results indicated a significant improvement in S-G for CMJd (∆% = +8.2%; p = 0.029; ES = 0.59) and for CMJAp (∆%= +8.7%; p = 0.035; ES = 0.44). These improvements were significant compared to H-G for CMJAd (F1,12 = 8.50; p = 0.013; η2p = 0.41; ES = 0.83) and CMJAp (F1,12 = 7.69; p = 0.017; η2p = 0.39; ES = 0.79). This study reveals that performance related to countermovement jump with arms on softer surface after 4-week of plyometric training was effective in improving vertical jump displacement and lower body power in rugby sevens players.
In spite of the extensive research for developing new therapies, prostate cancer is still one of the major human diseases with poor prognosis and high mortality. Therefore, with the aim of identifying novel agents with antigrowth and pro-apoptotic activity on prostate cancer cells, in the present study, we evaluated the effect of lichen secondary metabolite physodic acid on cell growth in human prostate cancer cells. In addition, we tested the apoptotic activity of physodic acid on TRAIL-resistant LNCaP cells in combination with TRAIL. The cell viability was measured using MTT assay. LDH release, a marker of membrane breakdown, was also measured. For the detection of apoptosis, the evaluation of DNA fragmentation and caspase-3 activity assay were employed. The expression of proteins was detected by Western blot analysis. It was observed that physodic acid showed a dose-response relationship in the range of 12.5-50 μM concentrations in LNCaP and DU-145 cells, activating an apoptotic process. In addition, physodic acid sensitizes LNCaP cells to TRAIL-induced apoptosis. The combination of physodic acid with other anti-prostate cancer therapies could be considered a promising strategy that warrants further investigations.
Effective bidding on multiple electricity products under uncertainty would allow a more profitable market participation for hybrid power plants with variable energy resources and storage systems, therefore aiding the decarbonization process. This study deals with the effective bidding of a photovoltaic plant with an energy storage system (PV-ESS) participating in multi-timescale electricity markets by providing energy and ancillary services (AS) products. The energy management system (EMS) aims to maximize the plant’s profits by efficiently bidding in the day-ahead and real-time markets while considering the awarded products’ adequate delivery. EMS’s bidding decisions are usually obtained from traditional mathematical optimization frameworks. However, since the addressed problem is a multi-stage stochastic program, it is often intractable and suffers the curse of dimensionality. This paper presents a novel multi-agent deep reinforcement learning (MADRL) framework for efficient multi-timescale bidding. Two agents based on multi-view artificial neural networks with recurrent layers (MVANNs) are adjusted to map environment observations to actions. Such mappings use as inputs available information related to electricity market products, bidding decisions, solar generation, stored energy, and time representations to bid in both electricity markets. Sustained by a price-taker assumption, the physically and financially constrained EMS’s environment is simulated by employing historical data. A shared cumulative reward function with a finite time horizon is used to adjust both MVANNs’ weights simultaneously during the learning phase. We compare the proposed MADRL framework against scenario-based two-stage robust and stochastic optimization methods. Results are provided for one-year-round market participation of the hybrid plant at a 1-minute resolution. The proposed method achieved statistically significant higher profits, less variable incomes from both electricity markets, and better provision of awarded products by achieving smaller and less variable energy imbalances through time.
This work analyses two texts published by female Chilean poets at the end of the eighties: Poemas insurrectos (1988) by Heddy Navarro and Género femenino by Teresa Calderón. In line with the importance that collective action of women assumes against the dictatorship, even by participating in groups of armed resistance such as the MIR or the FPMR, these authors create a feminine subjectivity traced by the guerrilla language. Insurrection, barricades, and strikes are reiterative signifiers in their texts, so we wonder what functions that type of enunciation performs. Thus, it is proposed that both poets construct the voice of subversive women to represent the fight for "democracy in the country and in the home" that the feminist movement is raising at that time. These poets defy gender roles decreed by the regime and patriarchal culture, proclaiming the microphysic powers that women possess to emancipate from authoritarian violence.
Tsunamis are natural phenomena that, although occasional, can have large impacts on coastal environments and settlements, especially in terms of loss of life. An accurate, detailed and timely assessment of the hazard is essential as input for mitigation strategies both in the long term and during emergencies. This goal is compounded by the high computational cost of simulating an adequate number of scenarios to make robust assessments. To reduce this handicap, alternative methods could be used. Here, an enhanced method for estimating tsunami time series using a one-dimensional convolutional neural network model (1D CNN) is considered. While the use of deep learning for this problem is not new, most of existing research has focused on assessing the capability of a network to reproduce inundation metrics extrema. However, for the context of Tsunami Early Warning, it is equally relevant to assess whether the networks can accurately predict whether inundation would occur or not, and its time series if it does. Hence, a set of 6776 scenarios with magnitudes in the range Mw 8.0–9.2 were used to design several 1D CNN models at two bays that have different hydrodynamic behavior, that would use as input inexpensive low-resolution numerical modeling of tsunami propagation to predict inundation time series at pinpoint locations. In addition, different configuration parameters were also analyzed to outline a methodology for model testing and design, that could be applied elsewhere. The results show that the network models are capable of reproducing inundation time series well, either for small or large flow depths, but also when no inundation was forecast, with minimal instances of false alarms or missed alarms. To further assess the performance, the model was tested with two past tsunamis and compared with actual inundation metrics. The results obtained are promising, and the proposed model could become a reliable alternative for the calculation of tsunami intensity measures in a faster than real time manner. This could complement existing early warning system, by means of an approximate and fast procedure that could allow simulating a larger number of scenarios within the always restricting time frame of tsunami emergencies.
The misuse of psychostimulants is an increasing behavior among young people, highlighting in some countries the abuse of modafinil (MOD) as a neuropotentiator. However, several clinical trials are investigating MOD as an alternative pharmacological treatment for attentional deficit and hyperactivity disorder (ADHD) in children and adolescents. On the other hand, the early use of psychostimulants and the misdiagnosis rates in ADHD make it crucial to investigate the brain effects of this type of drug in young healthy individuals. The aim of this work was to evaluate the effects of chronic MOD treatment on neurochemicals (γ-aminobutyric acid and glutamate), dopamine receptor 2 (D2) expression and behavior (non-selective attention “NSA”) in the mesocorticolimbic system of young healthy Sprague–Dawley rats. Preadolescent male rats were injected with MOD (75 mg/kg, i.p.) or a vehicle for 14 days (from postnatal day 22 to 35). At postnatal day 36, we measured the GLU and GABA contents and their extracellular levels in the nucleus accumbens (NAc). In addition, the GLU and GABA contents were measured in the ventral tegmental area (VTA) and D2 protein levels in the prefrontal cortex (PFC). Chronic use of MOD during adolescence induces behavioral and neurochemical changes associated with the mesocorticolimbic system, such as a reduction in PFC D2 expression, VTA GABA levels and NSA. These results contribute to the understanding of the neurological effects of chronic MOD use on a young healthy brain.
Tourist eXperience (TX) is a concept discussed by many authors over the last couple of decades. TX can be approached as a particular case of Costumer eXperience (CX). TX evaluation is complex and challenging, due to its multidimensional nature, and because TX is highly personal. General and specific TX scales have been proposed. Tourism was extremely affected by the COVID-19 global pandemic. New concerns and procedures have emerged for safe trips, and they will likely become the norm in the post-pandemic era. Our study aims to develop a scale to evaluate TX in Valparaíso, Chile. We present a preliminary version of the scale, that includes 56 items, grouped in 8 dimensions: emotions, local culture, authenticity of the place, entertainment, services, post-pandemic experience, loyalty, and general perception. It includes 13 original items, and 43 adapted items, from other authors. The scale will be further validated and refined based on experts’ judgment, experiments, and statistical validation.
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1,465 members
Freddy Celis
  • Departamento de Ciencias y Geografía
Héctor A. Levipan
  • Facultad de Ciencias Naturales y Exactas
Hamish Iain Stewart
  • Departamento de Literatura
Veronica Molina
  • Facultad de Ciencias Naturales y Exactas
Marisol Belmonte
  • Departamento de Medio Ambiente
Avenida Playa Ancha 850, Valparaíso, Chile
Head of institution
Sr. Patricio Sanhueza Vivanco, Rector