Publicaciones académicas

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Esta colección incluye artículos de profesores de la Pontificia Universidad Católica de Chile, publicados en revistas nacionales y extranjeras.

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A class of random fields with two-piece marginal distributions for modeling point-referenced data with spatial outliers
(2022) Bevilacqua, Moreno; Caamano-Carrillo, Christian; Arellano-Valle, Reinaldo B.; Gomez, Camilo
In this paper, we propose a new class of non-Gaussian random fields named two-piece random fields. The proposed class allows to generate random fields that have flexible marginal distributions, possibly skewed and/or heavy-tailed and, as a consequence, has a wide range of applications. We study the second-order properties of this class and provide analytical expressions for the bivariate distribution and the associated correlation functions. We exemplify our general construction by studying two examples: two-piece Gaussian and two-piece Tukey-h random fields. An interesting feature of the proposed class is that it offers a specific type of dependence that can be useful when modeling data displaying spatial outliers, a property that has been somewhat ignored from modeling viewpoint in the literature for spatial point referenced data. Since the likelihood function involves analytically intractable integrals, we adopt the weighted pairwise likelihood as a method of estimation. The effectiveness of our methodology is illustrated with simulation experiments as well as with the analysis of a georeferenced dataset of mean temperatures in Middle East.
A cost-benefit approach to recover the performance of roads affected by natural disasters
(2021) Cartes, P. C.; Echaveguren, Tomás; Giné, A. C.; Binet, E. A.
A dynamic simulation model to support reduction in illegal trade within legal wildlife markets
(2022) Oyanedel, Rodrigo; Gelcich, Stefan; Mathieu, Emile; Milner-Gulland, E. J.
Sustainable wildlife trade is critical for biodiversity conservation, livelihoods, and food security. Regulatory frameworks are needed to secure these diverse benefits of sustainable wildlife trade. However, regulations limiting trade can backfire, sparking illegal trade if demand is not met by legal trade alone. Assessing how regulations affect wildlife market participants' incentives is key to controlling illegal trade. Although much research has assessed how incentives at both the harvester and consumer ends of markets are affected by regulations, little has been done to understand the incentives of traders (i.e., intermediaries). We built a dynamic simulation model to support reduction in illegal wildlife trade within legal markets by focusing on incentives traders face to trade legal or illegal products. We used an Approximate Bayesian Computation approach to infer illegal trading dynamics and parameters that might be unknown (e.g., price of illegal products). We showcased the utility of the approach with a small-scale fishery case study in Chile, where we disentangled within-year dynamics of legal and illegal trading and found that the majority (similar to 77%) of traded fish is illegal. We utilized the model to assess the effect of policy interventions to improve the fishery's sustainability and explore the trade-offs between ecological, economic, and social goals. Scenario simulations showed that even significant increases (over 200%) in parameters proxying for policy interventions enabled only moderate improvements in ecological and social sustainability of the fishery at substantial economic cost. These results expose how unbalanced trader incentives are toward trading illegal over legal products in this fishery. Our model provides a novel tool for promoting sustainable wildlife trade in data-limited settings, which explicitly considers traders as critical players in wildlife markets. Sustainable wildlife trade requires incentivizing legal over illegal wildlife trade and consideration of the social, ecological, and economic impacts of interventions.
A First Omics Data Integration Approach in Hass Avocados to Evaluate Rootstock-Scion Interactions: From Aerial and Root Plant Growth to Fruit Development
(2024) Nunez-Lillo, Gerardo; Ponce, Excequel; Beyer, Clemens P.; Alvaro, Juan E.; Meneses, Claudio; Pedreschi, Romina
Grafting, the careful selection of rootstocks and scions, has played a crucial role maintaining Chilean avocado fruit quality standards in a scenario in which climate change and drought-related issues have considerably decreased avocado fruit production in the last fifteen years. The historical use of seedling rootstocks in Chile has experienced a recent shift towards clonal rootstocks, driven by the potential to produce more consistent and predictable crops. This research aims to compare Hass avocado plants grafted on Mexicola seedling and Dusa (R) clonal rootstocks in a soilless and protected system using (i) a differential expression analysis of root and leaf samples and (ii) a fruit transcriptomic and metabolomic integration analysis to improve our understanding of rootstock-scion interaction and its impact on avocado tree performance and fruit quality. The results demonstrated that no significant transcriptomic and metabolomic differences were identified at fruit level in the ready-to-eat (RTE) stage for Hass avocado fruit from both rootstocks. However, Hass avocados grafted on the clonal rootstock showed greater aerial growth and slightly increased fruit size than the seedling rootstock due to the enrichment of cell wall-remodeling genes as revealed in leaves and fruit at harvest stage.
A framework for assessing and intervening in markets driving unsustainable wildlife use
(2021) Oyanedel, Rodrigo; Gelcich, Stefan; Milner-Gulland, E. J.
Understanding how markets drive unsustainable wildlife use is key for biodiversity conservation. Yet most approaches to date look at isolated components of wildlife markets, hindering our ability to intervene effectively to improve sustainability. To better assess and intervene in wildlife markets, we propose a framework that integrates three analytical levels. The first level, "actor", assesses the underlying motivations and mechanisms that allow or constrain how actors benefit from wildlife markets. The second level, "inter-actor", assesses the config-uration of wildlife product supply-chains and the type of competition between actors participating in wildlife markets. The third level, "market", evaluates supply-demand dynamics, quantity and price determinants, and the presence and effect of illegal products flowing into markets. We showcase the utility of the framework in a data-limited small-scale fishery case study (common hake, Merluccius gayi gayi in Chile); our mixed-method analysis provided relevant, tailored management recommendations for improving sustainability. Tackling markets driving unsustainable wildlife use needs integrated approaches that bring together the diversity of factors affecting wildlife market dynamics. (c) 2021 Elsevier B.V. All rights reserved.
A holistic view of nitrogen acquisition in plants
(2011) Kraiser Miranda, Tatiana Diannela; Gutiérrez Ilabaca, Rodrigo Antonio
A KINETIC INTERPRETATION OF TEXTURAL CHANGES IN BLACK BEANS DURING PROLONGED STORAGE
(1987) AGUILERA, JM; BALLIVIAN, A
Control and roasted (80.degree.C), dry black beans (Phaseolus vulgaris) were stored for 9 months at 8, 10, 12, and/or 14% moisture content and 8.5.degree., 25.degree., and 40.degree.C. Similarly, beans heated in a solid-to-solid roaster to 51.degree., 61.degree., 72.3.degree., 80.degree., 85.5.degree., 89.5.degree., 101.degree., and 111.degree.C were maintained at 8% moisture and 25.degree.C. Final hardness increased with moisture content and temperature. Hardening at 8.5.degree. and 25.degree.C proceeded initially almost linearly reaching a constant value after 4 to 6 months while at 40.degree.C it was sigma-shaped. A pseudo-zero order kinetic model fitted for initial rates had an activation energy of 6-11.8 kcal/mol. The hardening rate at 25.degree.C paralleled the shape of the sorption isotherm.
A mediation analysis to disentangle relations between maternal education and early child development
(2022) Telias, Amanda; Narea, Marigen; Abufhele, Alejandra
Maternal education is associated with early child outcomes. However, the several mechanisms that may explain this relationship remain underexplored. Using data from 1,097 children aged 12-15 months in Chile, we estimate the maternal education gap across child cognitive and language outcomes. Following a bioecological perspective, we explore potential pathways by which maternal education might influence child development, such as child characteristics, the quantity and quality of mother-child interactions, and the availability of home stimulation. We found an average maternal education gap between children with mothers with the lowest and the highest educational levels of 0.36, 0.31, and 0.25 standard deviation in child cognition, expressive language, and receptive language, respectively. The mediational analysis showed that maternal stress and depression and the quality of the home environment mediated the relation between maternal education and child language and cognitive development.
A modeling approach to determining the relationship between vegetative filter strip design and sediment composition
(2017) Lobo, G.; Bonilla Meléndez, Carlos Alberto; CEDEUS (Chile)
A multipurpose portable instrument for determining ripeness in wine grapes using NIR spectroscopy
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2008) Larrain, Manuel; Guesalaga, Andres R.; Agosin, Eduardo
This paper describes the development of a noninvasive instrument that is designed to measure three parameters of ripeness in wine grapes, i.e., sugar (Brix), pH, and anthocyanin concentration. The instrument is based on near-infrared spectroscopy, and it comes in contact with the berry in the cluster without altering its ripening process. A thorough description of the calibration process for the instrument is done for the different grape varieties, e.g., Cabernet Sauvignon, Carmenere, Merlot, Pinot Noir, and Chardonnay. Samples from vineyards located in the Maipo Valley (Chile) taken during the 2003 season were processed to develop calibration models using partial least squares techniques. The models were validated in terms of root mean square error of validation and R-2 indices. The results show the great potential of this technique regarding Brix and pH measurements. For the anthocyanin concentration measurements, the results are promising but require an accurate procedure to obtain reference values for model calibration. The instrument can be useful for sampling strategies that look for optimum harvest schedules according to grape maturity in terms of not only sugar content but also pH and anthocyanin concentration.
A network of stress-related genes regulates hypocotyl elongation downstream of selective auxin perception
(2021) Rigal, Adeline; Doyle, Siamsa M.; Ritter, Andres; Raggi, Sara; Vain, Thomas; O'Brien, Jose Antonio; Goossens, Alain; Pauwels, Laurens; Robert, Stephanie
The plant hormone auxin, a master coordinator of development, regulates hypocotyl elongation during seedling growth. We previously identified the synthetic molecule RubNeddin 1 (RN1), which induces degradation of the AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) transcriptional repressors INDOLE-3-ACETIC ACID-INDUCIBLE3 (IAA3) and IAA7 in planta and strongly promotes hypocotyl elongation. In the present study, we show that despite the structural similarity of RN1 to the synthetic auxin 2,4-dichlorophenoxyacetic-acid (2,4-D), direct treatments with these compounds in Arabidopsis (Arabidopsis thaliana) result in distinct effects, possibly due to enhanced uptake of RN1 and low-level, chronic release of 2,4-D from RN1 in planta. We confirm RN1-induced hypocotyl elongation occurs via specific TRANSPORT INHIBITOR RESISTANT1 (TIR1)/AUXIN SIGNALING F-BOX (AFB) receptor-mediated auxin signaling involving TIR1, AFB2, and AFB5. Using a transcriptome profiling strategy and candidate gene approach, we identify the genes ZINC FINGER OF ARABIDOPSIS THALIANA10 (ZAT10), ARABIDOPSIS TOXICOS EN LEVADURA31 (ATL31), and WRKY DNA-BINDING PROTEIN33 (WRKY33) as being rapidly upregulated by RN1, despite being downregulated by 2,4-D treatment. RN1-induced expression of these genes also occurs via TIR1/AFB-mediated auxin signaling. Our results suggest both hypocotyl elongation and transcription of these genes are induced by RN1 via the promoted degradation of the AUX/IAA transcriptional repressor IAA7. Moreover, these three genes, which are known to be stress-related, act in an inter-dependent transcriptional regulatory network controlling hypocotyl elongation. Together, our results suggest ZAT10, ATL31, and WRKY33 take part in a common gene network regulating hypocotyl elongation in Arabidopsis downstream of a selective auxin perception module likely involving TIR1, AFB2, and AFB5 and inducing the degradation of IAA7.
A new method of assessing water erosion risk in forest operations based on rainfall variability
(UNIV AUSTRAL CHILE, FAC CIENCIAS FORESTALES, 2012) Contreras, Juan; Bonilla, Carlos A.; Troncoso, Juan
Water erosion has been a major environmental problem associated to forest harvesting operations in humid and temperate climates. The incorporation of this factor in the decision making process has been complex due to the high variability observed in rainfall intensity and magnitude. This paper presents a methodology for incorporating the temporal variability of rainfall in the planning of forest operations. We used a monthly index based on the R-RUSLE erosivity factor. This index allows knowing the most likely value of soil loss and associating a confidence level. Thus, the forest planner has an estimate of erosion rates related to the operations, and an index that reflects the rainfall variability. With this methodology it is possible to identify, for a given level of soil loss, those months in which there is a higher uncertainty. This methodology was applied to a pine plantation in Santa Barbara, Biobio Region, Chile, where the rainfall erosivity ranges from 16 MJ mm ha(-1) h(-1) to 271 MJ mm ha(-1) h(-1) depending on the month of the year.
A new species of Pseudococcus (Hemiptera: Pseudococcidae) belonging to the "Pseudococcus maritimus" complex from Chile: molecular and morphological description
(MAGNOLIA PRESS, 2011) Correa, Margarita; Aguirre, Carlos; Germain, Jean Francois; Hinrichsen, Patricio; Zaviezo, Tania; Malausa, Thibaut; Prado, Ernesto
A new species of mealybug from Chile, Pseudococcus meridionalis Prado sp. n., is described and illustrated based on the morphological and molecular characterization of adult females. This species belongs to the "Pseudococcus maritimus" complex and displays a wide host plant range, including Japanese pear, persimmon, pomegranate, pear and grape.
A non-destructive digital imaging method to predict immobilized yeast-biomass
(ELSEVIER, 2009) Acevedo, Cristian A.; Skurtys, Olivier; Young, Manuel E.; Enrione, Javier; Pedreschi, Franco; Osorio, Fernando
In food fermentation, many types of immobilization systems are used, such as hydrogel entrapment, where alginate is the main biopolymer. one of the important problems in industrial processes is the quantifications of biomass, since the traditional system of direct cell counting cannot be used. In this study, a simple digital imaging method to determine the biomass of yeasts immobilized into alginate capsules was developed. Important evidence of the yeasts growing inside the alginate was the change in the surface color of the capsule. Digital images were taken with different biomass concentration, and the RGB-analysis showed significant differences in the blue field. The histogram of the blue channel was used to develop a PLS multivariate calibration to predict biomass concentration. The method was validated in primary beer fermentation with good efficiency. (C) 2009 Elsevier Ltd. All rights reserved.
A Past Genetic Bottleneck from Argentine Beans and a Selective Sweep Led to the Race Chile of the Common Bean (Phaseolus vulgaris L.)
(2024) Arriagada, Osvin; Arevalo, Barbara; Pacheco, Igor; Schwember, Andres R.; Meisel, Lee A.; Silva, Herman; Marquez, Katherine; Plaza, Andrea; Perez-Diaz, Ricardo; Pico-Mendoza, Jose; Cabeza, Ricardo A.; Tapia, Gerardo; Fuentes, Camila; Rodriguez-Alvarez, Yohaily; Carrasco, Basilio
The domestication process of the common bean gave rise to six different races which come from the two ancestral genetic pools, the Mesoamerican (Durango, Jalisco, and Mesoamerica races) and the Andean (New Granada, Peru, and Chile races). In this study, a collection of 281 common bean landraces from Chile was analyzed using a 12K-SNP microarray. Additionally, 401 accessions representing the rest of the five common bean races were analyzed. A total of 2543 SNPs allowed us to differentiate a genetic group of 165 accessions that corresponds to the race Chile, 90 of which were classified as pure accessions, such as the bean types 'Tortola', 'Sapito', 'Coscorron', and 'Frutilla'. Our genetic analysis indicates that the race Chile has a close relationship with accessions from Argentina, suggesting that nomadic ancestral peoples introduced the bean seed to Chile. Previous archaeological and genetic studies support this hypothesis. Additionally, the low genetic diversity (pi = 0.053; uHe = 0.53) and the negative value of Tajima' D (D = -1.371) indicate that the race Chile suffered a bottleneck and a selective sweep after its introduction, supporting the hypothesis that a small group of Argentine bean genotypes led to the race Chile. A total of 235 genes were identified within haplotype blocks detected exclusively in the race Chile, most of them involved in signal transduction, supporting the hypothesis that intracellular signaling pathways play a fundamental role in the adaptation of organisms to changes in the environment. To date, our findings are the most complete investigation associated with the origin of the race Chile of common bean.
A portable non-destructive volume meter for wine grape clusters
(2006) Iraguen, Vicente; Guesalaga, Andres; Agosin, Eduardo
A portable non-destructive instrument has been developed for the measurement of grape cluster volume using air displacement techniques. The design satisfies the producer's need to determine cluster growth curves in order to estimate the optimum time to start the harvest. Several ways of processing data were evaluated, including different models and parameters related to thermodynamic, mechanical and electronic aspects. Using an empirical calibration technique, the device performs with an acceptable accuracy for field measurements, with errors below 20 cm(3) and R-2 higher than 0.92. It is intended for sample volumes between 80 cm(3) and 500 cm(3). The instrument was intensively tested in three vineyards and for different atmospheric pressures, achieving good results and validating its use for harvest volume estimation. The instrument can be adapted so that it can be used for other types of fruit and vegetables.
A randomized trial of a screening, case finding, and referral system for older veterans in primary care
(WILEY, 2007) Rubenstein, Laurence Z.; Alessi, Cathy A.; Josephson, Karen R.; Hoyl, M. Trinidad; Harker, Judith O.; Pietruszka, Fern M.
OBJECTIVES: To test whether a system of screening, assessment, referral, and follow-up provided within primary care for high-risk older outpatients improves recognition of geriatric conditions and healthcare outcomes.
A rapid, sensitive and inexpensive method for detection of grapevine red blotch virus without tissue extraction using loop-mediated isothermal amplification
(2019) Romero, J. L.; Carver, G. D.; Arce Johnson, Jorge Patricio; Perry, K. L.; Thompson, J. R.
A real options approach to the design and architecture of water supply systems using innovative water technologies under uncertainty
(2012) Zhang, Stephen X.; Babovic, Vladan
Water supply has become a priority for developed and developing nations of the world. Conventional water resources alone cannot meet the growing demand for water in urban cities. Management of the problem is amplified by uncertainty associated with different development strategies. Singapore has limited conventional water resources and progressively architects its water supply system through acquiring and sustaining multiple (alternative) water resources through innovative technologies. The full rationale and merits of such a policy cannot be properly understood based on traditional project valuation methods alone. This paper provides decision support using a real options approach by evaluating innovative water technologies from multiple perspectives under uncertainty. This paper demonstrates that incorporating innovative water technologies into water supply systems can concurrently improve water supply from the financial, political and socioeconomic perspectives. The development of innovative water technologies provides flexibility to the water supply system, and is a fundamental and effective means of risk management. The evaluation of innovative water technologies is based on an integrated real options approach, which provides decision support for architecting water supply systems under uncertainty. The approach gives specific tangible values for the water technologies and complements the general prescriptive Integrated Water Resources Management (IWRM) framework.
A remarkable synergistic effect at the transcriptomic level in peach fruits doubly infected by prunus necrotic ringspot virus and peach latent mosaic viroid
(2013) Herranz, Mari C.; Niehl, Annette; Rosales V., Marlene; Fiore, Nicola; Zamorano, Alan; Granell, Antonio; Pallas, Vicente
Abstract Background Microarray profiling is a powerful technique to investigate expression changes of large amounts of genes in response to specific environmental conditions. The majority of the studies investigating gene expression changes in virus-infected plants are limited to interactions between a virus and a model host plant, which usually is Arabidopsis thaliana or Nicotiana benthamiana. In the present work, we performed microarray profiling to explore changes in the expression profile of field-grown Prunus persica (peach) originating from Chile upon single and double infection with Prunus necrotic ringspot virus (PNRSV) and Peach latent mosaic viroid (PLMVd), worldwide natural pathogens of peach trees. Results Upon single PLMVd or PNRSV infection, the number of statistically significant gene expression changes was relatively low. By contrast, doubly-infected fruits presented a high number of differentially regulated genes. Among these, down-regulated genes were prevalent. Functional categorization of the gene expression changes upon double PLMVd and PNRSV infection revealed protein modification and degradation as the functional category with the highest percentage of repressed genes whereas induced genes encoded mainly proteins related to phosphate, C-compound and carbohydrate metabolism and also protein modification. Overrepresentation analysis upon double infection with PLMVd and PNRSV revealed specific functional categories over- and underrepresented among the repressed genes indicating active counter-defense mechanisms of the pathogens during infection. Conclusions Our results identify a novel synergistic effect of PLMVd and PNRSV on the transcriptome of peach fruits. We demonstrate that mixed infections, which occur frequently in field conditions, result in a more complex transcriptional response than that observed in single infections. Thus, our data demonstrate for the first time that the simultaneous infection of a viroid and a plant virus synergistically affect the host transcriptome in infected peach fruits. These field studies can help to fully understand plant-pathogen interactions and to develop appropriate crop protection strategies.Abstract Background Microarray profiling is a powerful technique to investigate expression changes of large amounts of genes in response to specific environmental conditions. The majority of the studies investigating gene expression changes in virus-infected plants are limited to interactions between a virus and a model host plant, which usually is Arabidopsis thaliana or Nicotiana benthamiana. In the present work, we performed microarray profiling to explore changes in the expression profile of field-grown Prunus persica (peach) originating from Chile upon single and double infection with Prunus necrotic ringspot virus (PNRSV) and Peach latent mosaic viroid (PLMVd), worldwide natural pathogens of peach trees. Results Upon single PLMVd or PNRSV infection, the number of statistically significant gene expression changes was relatively low. By contrast, doubly-infected fruits presented a high number of differentially regulated genes. Among these, down-regulated genes were prevalent. Functional categorization of the gene expression changes upon double PLMVd and PNRSV infection revealed protein modification and degradation as the functional category with the highest percentage of repressed genes whereas induced genes encoded mainly proteins related to phosphate, C-compound and carbohydrate metabolism and also protein modification. Overrepresentation analysis upon double infection with PLMVd and PNRSV revealed specific functional categories over- and underrepresented among the repressed genes indicating active counter-defense mechanisms of the pathogens during infection. Conclusions Our results identify a novel synergistic effect of PLMVd and PNRSV on the transcriptome of peach fruits. We demonstrate that mixed infections, which occur frequently in field conditions, result in a more complex transcriptional response than that observed in single infections. Thus, our data demonstrate for the first time that the simultaneous infection of a viroid and a plant virus synergistically affect the host transcriptome in infected peach fruits. These field studies can help to fully understand plant-pathogen interactions and to develop appropriate crop protection strategies.

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